U.S. patent application number 15/502139 was filed with the patent office on 2017-08-10 for device and method for blasting a suspension onto workpieces.
The applicant listed for this patent is Werner Hunziker. Invention is credited to Remo Giger, Werner Hunziker, Jurg Scholz.
Application Number | 20170225296 15/502139 |
Document ID | / |
Family ID | 53783711 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170225296 |
Kind Code |
A1 |
Hunziker; Werner ; et
al. |
August 10, 2017 |
Device And Method For Blasting A Suspension Onto Workpieces
Abstract
A device for irradiating a suspension on workpieces, the device
including at least one pressure vessel for the suspension; at least
one feed line for the suspension connected to the pressure vessel,
the feed line is connected or can be connected to a radiation
device; at least one valveswitched between the pressure vessel and
the radiation device; at least one prechamber connected to the
pressure vessel by a valve; at least one return line for the
suspension, connected to the prechamber; and a line and a valve, by
which the prechamber can be connected to a compressed air source or
by which the prechamber is connected to a compressed air source.
The valve between the prechamber and the pressure vessel is a check
valve connected at its one upper, connection at a pressure vessel
connection, which discharges into the pressure vessel through the
bottom of the pressure vessel at the lowest point thereof, and
which is connected at its other connection to the prechamber,
wherein the flow direction of the check valve is directed toward
the pressure vessel.
Inventors: |
Hunziker; Werner;
(Maienfeld, CH) ; Scholz; Jurg; (Zizers, CH)
; Giger; Remo; (Chur, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hunziker; Werner |
|
|
US |
|
|
Family ID: |
53783711 |
Appl. No.: |
15/502139 |
Filed: |
July 31, 2015 |
PCT Filed: |
July 31, 2015 |
PCT NO: |
PCT/EP2015/067624 |
371 Date: |
February 6, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24C 9/003 20130101;
B24C 7/0007 20130101 |
International
Class: |
B24C 7/00 20060101
B24C007/00; B24C 9/00 20060101 B24C009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2014 |
DE |
10 2014 111 043.9 |
Claims
1. A device, for blasting a suspension onto one or more workpieces,
wherein the device encompasses: at least one pressure vessel, at
least one feed line for suspension that is connected to the
pressure vessel, and is or can be connected to a blasting device,
at least one valve, which is switched between the pressure vessel
and blasting device, at least one prechamber, which is connected to
the pressure vessel by a valve, at least one return line for
suspension, which is connected to the prechamber by a valve, a line
and valve, with which the prechamber can be connected to a
compressed air source separate from the device, or with which the
prechamber is connected to a compressed air source belonging to the
device, characterized in that the valve between the prechamber and
pressure vessel is a check valve, which at its one, upper, terminal
is connected to a pressure vessel terminal that discharges into the
pressure vessel through the floor of the pressure vessel, and that
its other, lower, terminal is connected to the prechamber, wherein
the passage direction of the check valve is directed toward the
pressure vessel.
2. A device, for blasting a suspension onto one or more workpieces,
wherein the device encompasses: at least one pressure vessel, at
least one feed line for suspension that is connected to the
pressure vessel, and is or can be connected to a blasting device,
at least one valve, which is switched between the pressure vessel
and blasting device, at least one prechamber, which is connected to
the pressure vessel by a valve, at least one return line for
suspension, which is connected to the prechamber, by a valve, a
line and valve, with which the prechamber can be connected to a
compressed air source separate from the device, or with which the
prechamber is connected to a compressed air source belonging to the
device, characterized in that the device encompasses a vacuum
generating device, a vacuum injector or a vacuum pump, to which the
prechamber is connected by means of at least one line and one
valve, and/or that a pump is switched between the prechamber and
return line, or a pump is connected to the end of the return line
facing away from the prechamber, wherein the conveying direction of
the pump during operation is directed toward the prechamber.
3. The device according to claim 2, characterized in that the valve
between the prechamber and pressure vessel is a check valve, which
at its one, upper, terminal is connected to a pressure vessel
terminal that discharges into the pressure vessel through the floor
of the pressure vessel, at its lowest point, and that its other,
lower, terminal is connected to the prechamber, wherein the passage
direction of the check valve is directed toward the pressure
vessel.
4. The device according to claim 1, characterized in that the
device encompasses a valve switched between the return line and
prechamber, which involves a check valve, wherein this check valve
at its one, upper, terminal is connected to a prechamber terminal
that discharges into the prechamber through the floor of the
prechamber, at its lowest point, and at its other, lower, terminal
is connected to the return line, and wherein the passage direction
of this check valve is directed toward the prechamber, and wherein
it is provided that this check valve is structurally identical to
the check valve switched between the prechamber and pressure
vessel.
5. The device according to claim 1, characterized in that the floor
of the pressure vessel has a conical or curved shape, so that the
cross section of the pressure vessel perpendicular to a vertical
direction tapers downwardly, and/or that the floor of the
prechamber has a conical or curved shape, so that the cross section
of the prechamber perpendicular to a vertical direction tapers
downwardly.
6. The device according to claim 1, characterized in that the
device encompasses at least one line and one valve, with which the
pressure vessel can be connected to a compressed air source
separate from the device, or with which the pressure vessel is
connected to a compressed air source belonging to the device.
7. The device according to claim 1, characterized in that the check
valve switched between the prechamber and pressure vessel and/or
the check valve switched between the return line and prechamber
encompasses the following: A sealing element comprised of an
elastically deformable material and a valve sleeve, which forms a
seal seat that expands in the passage direction of the check valve,
conically, wherein the sealing element forms a sealing edge
extending along its periphery, which when the sealing element moves
out of an open position in a direction toward the seal seat along
the sealing edge, initially only along a circle, comes into contact
with the seal seat.
8. The device according to claim 1, characterized in that the
sealing edge is bordered by two surfaces of the sealing element,
which in a cross section oriented transverse to its circumferential
direction run inclined to each other, at a right angle to each
other, wherein both surfaces of the sealing element each include an
acute angle with the surface of the seal seat in a cross section
perpendicular to the circumferential direction of the sealing
edge.
9. The device according to claim 1, characterized in that the
sealing element is accommodated in a longitudinally displaceable
manner in the valve sleeve parallel to its longitudinal central
axis, to which end the sealing element is connected with a guide
that leaves one or several flow-through openings, and on their
radially outer edge form a longitudinal guide with an inwardly
pointing cylindrical surface of the valve sleeve.
10. The device according to claim 1, characterized in that, when
moved from an open position toward the seal seat, the sealing edge
of the sealing element hits an annular zone of the seal seat spaced
apart from the tapered end of the seal seat, and that pressurizing
the sealing element against the seat seal triggers an elastic
deformation of the sealing element, as a result of which the
sealing element (66) abuts flat against the seal seat along its
circumference.
11. The device according to claim 1, characterized in that the feed
line extends through the wall of the pressure vessel into its
interior, wherein the distance between the mouth of the feed line
and lowest point of the pressure vessel measures less than one
eighth of the height of the interior of the pressure vessel.
12. The device according to claim 1, characterized in that the
check valve switched between the prechamber and pressure vessel is
connected to a riser pipe, at its lower terminal in the
installation position, which extends through the upper side wall of
the prechamber into its interior, wherein the distance between the
lower opening of the riser and the lowest point of the prechamber
measures less than one eighth, of the height of the interior of the
prechamber.
13. The device according to claim 1, characterized in that the
device encompasses a bypass line and a valve accommodated therein,
wherein the one end of the bypass line discharges into the interior
of the pressure vessel, at more than half of its height, inside of
an ascending sifter placed in the pressure vessel, and wherein the
other end of the bypass line discharges into the interior of the
prechamber, at less than half of its height.
14. The device according to claim 1, characterized in that the
device encompasses two prechambers, two return lines and four,
structurally identical, check valves, that the prechambers are
connected in parallel with each other and, interposing a respective
check valve, with the pressure vessel, and that a respective return
line is connected to a respective prechamber, interposing a
respective check valve.
15. The device according to claim 1, characterized in that at least
the pressure vessel, the prechamber or the prechambers, the check
valve(s), the bypass line or bypass lines, the vacuum generating
device and/or the pump as a combined assembly are situated in a
shared or cubic housing, out of which the feed line and return line
extend, that the assembly encompasses a compressed air terminal
that is or can be connected to a compressed air source that belongs
to the assembly or is separate from the assembly, that the
prechamber is connected to the compressed air terminal by at least
one valve, that the pressure vessel is connected to the compressed
air terminal by at least one valve, and that the vacuum generating
device and/or pump is connected to the compressed air terminal.
16. The device according to claim 1, characterized in that the
device is connected to a blasting cabin or encompasses a blasting
cabin, wherein the respective blasting cabin exhibits an interior
into which the feed line extends, and wherein the return line is
connected to a collection receptacle of the blasting cabin for
flowable media, wherein it is provided that the collection
receptacle always be in a state of pressure equalization with the
environment.
17. A method for wet blasting one or several workpieces, comprising
at least the following procedural steps: providing a device
according to claim 1, providing a blasting cabin if the provided
device encompasses no blasting cabin, introducing the blasting
device for the suspension and at least one longitudinal section of
the supply line for the suspension into the interior of the
blasting cabin, connecting one end of the return line for the
suspension to a collection receptacle of the blasting cabin for
flowable media, introducing suspension into the collection
receptacle of the blasting cabin, characterized by the following
procedural step: aspirating suspension through the end of the
return line connected to the collection receptacle of the blasting
cabin, by generating a vacuum in the prechamber and/or by turning
on a pump arranged between the collection receptacle and
prechamber, and opening a vent valve connected to the
prechamber.
18. The method according to claim 17, characterized in that the
method, subsequently, encompass at least: ending the aspiration of
suspension through the end of the return line connected to the
collection receptacle of the blasting cabin, supplying compressed
air into the prechamber at least partially filled with suspension,
and opening a vent valve connected to the pressure vessel, for
example which is a throttle valve or a pressure relief valve.
19. The method according to claim 17, characterized in that the
method, subsequently, encompass at least: aspirating suspension
through the end of the return line connected to the collection
receptacle of the blasting cabin, by generating a vacuum in the
prechamber and/or turning on a pump arranged between the collection
receptacle and prechamber, and opening a vent valve connected to
the prechamber, as this takes place, supplying compressed air to
generate overpressure in the pressure vessel at least partially
filled with suspension, and, given an overpressure in the pressure
vessel, at least intermittently opening the valve allocated to the
feed line so as to blast suspension onto one or several
workpieces.
20. The method according to claim 17, characterized in that the
method, subsequently, encompass at least: turning off the
compressed air supply in the pressure vessel, generating
overpressure in the prechamber by supplying compressed air into the
prechamber, given an overpressure in the prechamber, at least
intermittently opening the valve allocated to the feed line, and
blasting suspension onto one or several workpieces, and at least
intermittently opening a vent valve connected to the pressure
vessel.
21. The method according to claim 20, characterized in that the
steps of: turning off the compressed air supply in the pressure
vessel, generating overpressure in the prechamber by supplying
compressed air into the prechamber, given an overpressure in the
prechamber, at least intermittently opening the valve allocated to
the feed line, and blasting suspension onto one or several
workpieces, and at least intermittently opening a vent valve
connected to the pressure vessel are repeatedly executed
alternately in time relative to the steps of: aspirating suspension
through the end of the return line connected to the collection
receptacle of the blasting cabin, by generating a vacuum in the
prechamber and/or turning on a pump arranged between the collection
receptacle and prechamber, and opening a vent valve connected to
the prechamber, as this takes place, supplying compressed air to
generate overpressure in the pressure vessel at least partially
filled with suspension, and, given an overpressure in the pressure
vessel, at least intermittently opening the valve allocated to the
feed line so as to blast suspension onto one or several
workpieces.
22. The method according to claim 17, characterized in that the
method, subsequently, encompass at least: generating overpressure
in the pressure vessel by supplying compressed air into the
pressure vessel and opening the valve allocated to the bypass line,
so that at least the liquid phase of the suspension or the
suspension is transported from the pressure vessel into the
prechamber, once a specific level has been reached in the
prechamber, ending the supply of compressed air into the pressure
vessel and generating overpressure in the prechamber by supplying
compressed air, and in the process at least intermittently opening
a vent valve connected to the pressure vessel and/or opening the
valve allocated to the feed line for blasting suspension out of the
blasting device.
23. The method according to claim 17, characterized in that
suspension is blasted onto one or several workpieces, wherein the
weight ratio between the overall solid phase contained in the
suspension and the overall liquid phase contained in the suspension
has the value 1.
24. A method according to claim 1, characterized in that suspension
is blasted onto one or several workpieces, wherein the weight ratio
between the overall solid phase contained in the suspension and the
overall liquid phase contained in the suspension is greater than
0.5.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a device, in particular for
blasting a suspension onto one or more workpieces, wherein the
device encompasses: At least one pressure vessel for the
suspension, at least one feed line for the suspension connected to
the pressure vessel at its one end, the other end of which is or
can be connected to a blasting device, which can preferably be a
blasting gun, at least one valve that is switched between the
pressure vessel and blasting device, at least one prechamber for
the suspension, which is connected to the pressure vessel with at
least one valve interposed, at least one return line for the
suspension, which is connected to the prechamber, preferably with a
valve interposed, and a line and a valve, with which the prechamber
is or can be connected to a compressed air source separate from the
device, or with which the prechamber is connected to a compressed
air source belonging to the device.
BACKGROUND OF THE INVENTION
[0002] Generic devices are conventionally used for the surface
treatment of workpieces by having the pressure from a blasting gun
apply (i.e., "blast") a suspension containing water and preferably
fine-grained blasting agents onto the workpiece surface. Such a wet
blasting treatment can have a grinding effect on the workpiece
surface, for example, due to the abrasively acting blasting agent.
Also known is a dry blasting treatment, in which a blasting agent
is blasted onto the surface of workpieces without a liquid
phase.
[0003] Very fine-grained, as a rule mineral, blasting agents, such
as corundum, silicon carbide, glass powder, glass pearls, ceramic
pearls, etc., can be used dry in blasting systems only to a very
limited extent, because in addition to undesirably forming dust,
they have virtually no effect on the surface of a workpiece to be
machined. For this reason, they are reacted with a liquid, as a
rule water, for purposes of wet blasting. This flowable mixture,
consequently referred to as a suspension, can be handled similarly
to a liquid, e.g., conveyed by a pump in pipes or tubes. One major
challenge in systems or blasting devices that work with such
suspensions involves the extremely specific differences in weight
between the liquid phase and solid blasting agents in the
suspension. For example, the ratio for the specific weight between
water and corundum measures 1:4. An attempt is often made to keep
the blasting agent suspended by means of agitating mechanisms.
However, since such devices operate with rotating elements, there
is a tendency for the blasting agent therein to nonetheless be
deposited in the outer regions. This is more or less of a problem,
depending on the blasting agent concentration in the suspension.
For this reason, low concentrations have as a rule been used
previously, at which the weight ratio between the solid blasting
agent and liquid phase in the suspension lies within a value range
of only 1:10-1:20. One requirement and concurrent difficulty has to
do with the uniform distribution of the blasting agent in the
liquid. The blasting result on a workpiece will to a great extent
be advantageously influenced by a uniform distribution, and
disadvantageously influenced by a non-uniform distribution. In
order to be able to pump a suspension for a blasting process, there
is also the difficulty that a centrifugal pump also acts as a
centrifuge, for example, i.e., that it causes the heavier blasting
agent to separate from the water, which is lighter by comparison.
The higher the blasting agent concentration, the more serious the
separation effect as well. This can also result in two streams
forming next to each other in a pipe system, one rapidly flowing
liquid stream and one slowly blasting agent stream.
[0004] In conventional blasting systems, the suspension is as a
rule conveyed into an injector blasting gun by a centrifugal pump.
Also known is to blow compressed air into the suspension stream.
However, a large portion of the water is atomized or evaporated as
a result, and the blasting agent grains impacting the workpiece
thus have more or less the same "hacking" effect as when dry
blasting without liquid. The difference then practically lies only
in the absence of a dust problem. A generic device of the kind
mentioned at the outset is known in prior art from WO 2013/079490
A2.
SUMMARY OF THE INVENTION
[0005] The object of the invention is to advantageously further
develop such a generic device. In particular, the aim is to be able
to thereby entirely or at least partially eliminate individual or
several of the described previously existing limitations and
disadvantages. The aim in particular is to advantageously further
develop a generic device for blasting suspensions, thereby making a
suspension suitable for the blasting process that has a higher
percentage of blasting agent by comparison to the weight ratios
indicated above possible in prior art. In particular, the aim is
further to not have to blow compressed air into the suspension
before the blasting nozzle, and spread or atomize the suspension
jet.
[0006] In a first aspect of the invention, the object is initially
and essentially achieved in conjunction with the features in which
the valve between the prechamber and pressure vessel is a check
valve, which at its one, preferably upper, terminal is connected
directly or indirectly to a pressure vessel terminal that
discharges into the pressure vessel through the floor of the
pressure vessel, preferably at its lowest point, and its other,
preferably lower, terminal is directly or indirectly connected to
the prechamber, wherein the passage direction of the check valve is
directed toward the pressure vessel, and the blocking direction of
the check valve is directed toward the prechamber. The pressure
vessel is preferably located above, either directly above or
laterally above, the prechamber. In light of the described
components, reference could also be made to a blasting installation
or a blasting system instead of a blasting device. Within the
framework of the invention, the term connected or terminal includes
a direct or alternatively an indirect (e.g., interposing additional
components, such as lines, valves or the like) terminal. A terminal
permits a fluidic connection, which either exists permanently or,
given an interposed valve, with the valve open.
[0007] The features proposed by the invention make it possible to
supply a suspension into the pressure vessel from below through the
floor from the prechamber. This advantageously agitates the
suspension in the pressure vessel. The suspension directed upwardly
from below, i.e., against gravity, enables a uniform distribution
of the blasting agent in the liquid phase of the suspension without
any additional measures.
[0008] In a preferred further development, the device can encompass
a vacuum generating device, for example a vacuum injector or a
vacuum pump, to which the prechamber is connected by means of at
least one line and one valve. Alternatively or additionally, for
example, a pump can be switched between the prechamber and return
line, or a pump can be connected to the end of the return line
facing away from the prechamber, wherein the conveying direction of
the pump during operation is directed toward the prechamber. In a
second aspect of the invention, these features can also be
important independently of the features of the first aspect of the
invention, i.e., also be independent of the characterizing features
in claim 1, optionally independent of or in combination with the
features indicated in the first section of the text. Here as well,
the device encompasses at least one pressure vessel for a
suspension and at least one prechamber for a suspension. If the
return line is connected to a collection receptacle of a blasting
cabinet for flowable media, e.g., for a suspension, these variants
each enable a transport of the suspension from the preferably
collection receptacle of a blasting cabin, which is preferably
ventilated, and thus at ambient temperature or at the pressure
prevailing inside the blasting cabin. In particular during the
blasting operation, the suspension that downwardly deposits,
downwardly flows, drips or the like in the interior of the blasting
cabin accumulates in such a collection receptacle of a blasting
cabin. Instead of a collection receptacle, reference could also be
made to a collection terminal. The collection terminal can
preferably be formed on the lower side, for example on the floor,
of the blasting cabin. It is possible for the collection receptacle
to encompass a receiving vessel that is at least partially open
toward the top or toward the interior of the blasting cabin
("blasting chamber"). For example, this can be a cup-shaped vessel.
For example, the vessel can be situated underneath an opening in
the floor of the blasting cabin, which is preferably located at the
lowest point of the floor, in particular underneath a grate.
Reference could also be made to a collection vessel for a
suspension or to an outflow vessel. The receiving vessel could also
be tubular in design. Depending on the capacity of the receiving
vessel, the collection receptacle can, alternatively or
additionally to a receiving vessel, encompass the in particular
funnel-shaped floor of the blasting cabin or a region thereof. If a
vacuum generating device is used to return a suspension, the
suspension can be conveyed from a collection receptacle for
flowable media (e.g., a suspension) of a blasting cabin back into
the pressure vessel, partially exposed to a negative pressure or
partially exposed to an overpressure, and the device according to
the invention requires neither pumps nor agitators given a suitable
configuration. Since the suspension flows into the pressure vessel
through a terminal in the floor, undesirable deposits of blasting
agent can be avoided.
[0009] In a conventional blasting process, even during conventional
wet blasting, blasting agent grains fly through the air from the
blasting nozzle up to the workpiece surface, and their effect is
based on their impact on the workpiece. Reference could thus be
made to a hacking effect. By way of derogation from the above, the
device according to the invention allows the solid particles added
to the liquid in the suspension to be always or at least
predominantly embedded in the liquid phase, so that their effect is
not one of hacking, but rather of grinding. Therefore, reference
could also be made to a device or method for liquid jet grinding.
As relates to the mentioned aspects of the invention, there are
numerous other options for preferred further development.
[0010] For example, it is possible for the device to encompass a
compressed air source. However, this is not necessary. In one
expedient embodiment, the device can be or is connected to a
compressed air source that is separate from it, e.g., in a manner
yet to be described.
[0011] In order to return a suspension from a blasting cabin, the
return line can be or is connected to the latter, specifically
preferably to a collection receptacle for flowable media, e.g., for
a suspension, of the blasting cabin.
[0012] The valve that can be used to connect the vacuum generating
device to the prechamber can preferably be a pneumatically or
electrically actuated valve, for example a so-called pinch valve,
which can be optionally opened or closed by means of a control
valve to be electrically switched.
[0013] It is possible for the device to encompass a valve switched
between the return line and prechamber, which consists of a check
valve whose passage direction is directed toward the prechamber,
and whose blocking direction is directed toward the return line. It
is preferred that this check valve be connected preferably at its
one, preferably upper, terminal directly or indirectly to a
prechamber terminal, which discharges into the prechamber through
the floor of the prechamber, preferably at its lowest point, and at
its other, preferably lower, terminal directly or indirectly to the
return line. It is possible for this check valve to be structurally
identical to the check valve switched between the prechamber and
pressure vessel. If this additional valve is connected to a floor
terminal of the prechamber, suspension is conveyed out of the
return line from the bottom up, i.e., against the sinking direction
of blasting agent in the suspension, and into the prechamber, which
then leads to a uniform mixing of the suspension even there.
[0014] For example, it is possible that the floor of the pressure
vessel have a conical or curved shape, so that the cross section of
the pressure vessel perpendicular to a vertical direction tapers
downwardly, and/or that the floor of the prechamber have a conical
or curved shape, so that the cross section of the prechamber
perpendicular to a vertical direction tapers downwardly.
[0015] It is possible that the device encompass at least one line
and one valve, with which the pressure vessel can be or is
connected to a compressed air source separate from the device, or
with which the pressure vessel is connected to a compressed air
source belonging to the device.
[0016] In order to be able to connect the prechamber in a preferred
embodiment to a compressed air source that does not comprise part
of the device, i.e., is external in relation to the device, it can
preferably be connected by means of a line and a valve to a
compressed air terminal of the device. In order to be able to
connect the pressure vessel in a preferred embodiment to a
compressed air source that does not comprise part of the device,
i.e., is external in relation to the device, it can preferably be
connected by means of a line and a valve to a compressed air
terminal of the device. Such a compressed air terminal of the
device is intended for compressed air supply in the device or from
an external compressed air supply line or, for example, directly
from an external compressed air source (e.g., a compressor).
Reference could therefore also be made to a compressed air
receiving terminal of the device. For example, the compressed air
terminal can encompass a pneumatic terminal element, e.g., a
pneumatic plug terminal or a pneumatic threaded terminal or the
like.
[0017] A vent valve is preferably connected to the pressure vessel.
A throttle valve or pressure relief valve can here preferably be
involved.
[0018] It is possible that the check valve switched between the
prechamber and pressure vessel and/or the check valve switched
between the return line and prechamber encompass at least the
following components: A sealing element comprised of an elastically
deformable material and a valve sleeve, which forms a seal seat
that expands in the passage direction of the check valve, in
particular conically, wherein the sealing element forms a sealing
edge extending along its periphery, which when the sealing element
moves out of an open position in a direction toward the seal seat
along the sealing edge, in particular initially only along a
circle, comes into contact with the seal seat.
[0019] Both check valves can preferably have an identical
structural design. Viewed as expedient is an installation position
for the check valves, in which the sealing element is located at
the top end of the valve, and the passage direction points from the
bottom up. If the sealing element is pressed toward the top from
the suspension flow, this opens an annular gap through which the
suspension can flow, and the check valve is in the open position.
If the flow moving toward the top comes to a standstill or an
unpressurized state arises, the sealing element that can move
relative to the valve sleeve (i.e., the valve body) sinks toward
the bottom under its own weight. The sealing element can preferably
be fabricated out of an elastic material, such as rubber or
polyurethane. To increase the weight, a plate, e.g., made of metal,
of a desired thickness can be secured thereto. The lower edge of
the sealing element can be sharp-edged at the sealing edge. As the
sealing element sinks down, the first contact with the inclined
valve seat thus takes place only in the form of a line. As a
result, the probability that blasting agent grains will get jammed
in the process is minimal. As soon as contact in the unpressurized
state has occurred, the suspension located above the sealing
element, which can be designed as a valve cone, bears down on the
latter from above, which leads to a certain pressure being exerted
on the valve seat. A certain additional pressure on the valve seat
can arise if a negative pressure exists in the prechamber. The
valve element is preferably constituted so as not to be deformed by
this yet. The sealing element is preferably designed in such a way
that it deforms at its outer edge that contacts the valve seat as
the pressure in the suspension located above the valve increases,
thereby resulting in a sealing surface, and the sealing element
further approaches the seal seat to some extent. The deformation
preferably does not take place suddenly; rather, a wedge-shaped gap
preferably arises first, which successively closes from the top
down, thereby downwardly forcing out liquid and solids. If no
pressure gradient from the top down is present any longer, or if a
pressure gradient from the bottom up prevails, the valve body once
again assumes its original shape. The movability of the sealing
element toward the valve seat is preferably limited, e.g., by means
of a positive stop, so as to limit the deformation of the sealing
element.
[0020] It is viewed as expedient that the sealing edge be bordered
by two surfaces of the sealing element, which in a cross section
oriented transverse to its circumferential direction run inclined
to each other, in particular at a right angle to each other,
wherein both surfaces of the sealing element each include an acute
angle with the surface of the seal seat in a cross section
perpendicular to the circumferential direction of the sealing edge.
Alternatively or additionally, it is possible that the sealing
element be accommodated in a longitudinally displaceable manner in
the valve sleeve parallel to its longitudinal central axis, to
which end the sealing element is connected in particular with
guiding means that leave one or several flow-through openings in
the valve cross section, and on their radially outer edge form a
longitudinal guide with an inwardly pointing cylindrical surface of
the valve sleeve. For example, the longitudinal guide can have a
slight radial clearance of approx. 0.5 mm, which ensures an exact
guidance. For example, the guiding means can be plate-like guiding
lamellae, e.g., which have a thickness of only about 2 mm. The
guiding lamellae thereby offer virtually no resistance to the flow,
and given the only narrow radial outer edge that interacts with the
valve sleeve as a guide, blockage by jammed blasting agents can be
precluded. The components of the check valves preferred by the
invention can also be removed and replaced in the event of
wear.
[0021] It is viewed as expedient that the feed line extends through
the wall of the pressure vessel and into the latter, wherein the
distance between the mouth of the feed line and lowest point of the
pressure vessel measures less than half, in particular less than
one fourth, in particular less than one eighth, of the height of
the interior of the pressure vessel. Alternatively or additionally,
it is possible for the check valve switched between the prechamber
and pressure vessel to be connected to a riser, in particular a
riser pipe, at its lower terminal in the installation position,
which extends through the upper side wall of the prechamber into
its interior, wherein the distance between the lower opening of the
riser and the lowest point of the prechamber measures less than
half, in particular less than one fourth, in particular less than
one eighth, of the height of the interior of the prechamber.
[0022] It is possible for the device to encompass a bypass line and
a valve accommodated therein, wherein the one end of the bypass
line discharges into the interior of the pressure vessel, in
particular at more than half or three fourths of its height, in
particular inside of an ascending sifter placed in the pressure
vessel, and wherein the other end of the bypass line discharges
into the interior of the prechamber, in particular at less than
half or one fourth of its height.
[0023] In a further development viewed as expedient, the device
encompasses two prechambers for a suspension, two return lines and
four, preferably structurally identical, check valves, the
prechambers are connected in parallel with each other and,
interposing a respective check valve between each prechamber and
the pressure vessel for the suspension, with the pressure vessel,
and a respective return line is connected to a respective
prechamber, interposing a respective check valve between the return
line and prechamber.
[0024] Viewed as an expedient embodiment is that at least the
pressure vessel, the prechamber or the prechambers, the check
valve(s), the bypass line or bypass lines, the vacuum generating
device and/or the pump as a combined assembly be situated in
particular in a shared or cubic housing, out of which the feed line
and return line extend, the assembly encompasses a compressed air
terminal that is or can be connected to a compressed air source
that belongs to the assembly or is separate from the assembly, the
prechamber is connected to the compressed air terminal by at least
one valve, the pressure vessel is connected to the compressed air
terminal by at least one valve, and the vacuum generating device
and/or pump is connected to the compressed air terminal. This
enables an autonomous configuration of the device according to the
invention. The blasting chamber need not be integrated into the
device according to the invention; rather, the device can also be
connected to a separate blasting chamber. The blasting chamber
serves to blast treat the workpiece and collect the suspension used
in the process in a collection receptacle, so as to return it to
the circulation. A separate controller can be used to provide the
device according to the invention even when blasting cabins are
present, and is thus also suitable for subsequently equipping or
converting blasting cabins. If the blasting cabin is not integrated
into the device according to the invention, it is also possible,
for example, to arrange all components of the device according to
the invention (possibly with the exception of certain longitudinal
sections of the feed and return lines) in a shared housing, for
example in a switch cabinet, which can also contain a
controller.
[0025] Depending on the different tasks at hand, nozzles with
varying size and varying shape (e.g., round, square or flat shapes)
can be used on the blasting device in the device according to the
invention. As evident from the preceding description, the device
according to the invention can be operated continuously. The
suspension flows from the pressure vessel to the blasting devices,
is collected in the blasting chamber once again, and conveyed back
into the pressure vessel again from the bottom up. This continuous
flow from the bottom up, i.e., opposite the blasting agent
deposition process in the liquid phase, produces a constant and
uniform mixing. An especially advantageous mixing of the suspension
is achieved by introducing the latter into the pressure vessel
through a terminal on the bottom side. Mixing can be improved even
further by also returning the suspension into the prechamber from
below through its floor. Even after prolonged downtimes, the device
according to the invention enables a restarting of a plant, even
after standing idle for several weeks. The described bypass line is
suitable for this purpose. After a prolonged operational
interruption or prolonged service life, the means described in
relation thereto can be used to extract clean liquid from the
pressure vessel via deposited blasting agent, and press it into the
prechamber from below. From there, the liquid or suspension can
again be pressed into the pressure vessel from below. Even a
compact mass in the pressure vessel can be broken up and again
mixed by taking this measure. Emulsion is preferably not stocked in
the prechamber for a prolonged period. Instead, it is preferred
that, once operation has been interrupted, e.g., with the
prechamber only partially filled, a transport process be
automatically initiated after a prescribed period of time, e.g.,
after approx. 2 minutes, in which suspension is pressed into the
pressure vessel from the prechamber. Even when turning off a plant,
the controller can first effect the evacuation of the
prechamber.
[0026] By comparison to the check valves preferred by the
invention, conventional, commercially available check valves with a
flap or ball would also be suitable as a sealing element for the
intended purpose, but less suitable for a variety of reasons.
Solids could also become deposited on the sealing element and
impede its function. Solids between the movable sealing element and
valve seat could hamper or prevent the seal. The check valves
preferred according to the invention are especially well suited for
the circumstances that exist during suspension blasting, especially
at a high blasting agent concentration. Apart from the tendency for
blasting agent to sink into the liquid phase, turbulences in the
mixture flow can also exert uncontrollable forces onto the movable
valve part in the case of such suspensions. Therefore, it is
preferred that the sealing element be precisely and robustly guided
and centered.
[0027] The invention also relates to a method for wet blasting one
or several workpieces, comprising at least the following procedural
steps: Providing a device that exhibits individual or several of
the preceding features; providing a blasting cabin if the provided
device encompasses no blasting cabin; introducing the blasting
device for the suspension, and in particular at least one
longitudinal section of the supply line for the suspension into the
interior of the blasting cabin; connecting one end of the return
line for the suspension to a collection receptacle for flowable
media (e.g., flowable suspension) of the blasting cabin, and
introducing flowable suspension into the collection receptacle of
the blasting cabin, e.g., for startup or, e.g., during operation of
the device. Against the backdrop of the prior art described at the
outset, the object of the invention is to advantageously further
develop a generic method, so that in particular individual or
several of the described limitations or disadvantages that
previously existed can be diminished or avoided. As a solution, the
invention proposes that the invention encompass the following as an
additional procedural step:Aspirating suspension through the end of
the return line connected to the collection receptacle of the
blasting cabin, preferably by generating a vacuum in the prechamber
and/or by turning on a pump arranged between the collection
receptacle and prechamber, and opening a vent valve connected to
the prechamber.
[0028] There are various options for preferred further development.
It is preferred that the method encompass at least the following
procedural step: Ending the aspiration of suspension through the
end of the return line connected to the collection receptacle of
the blasting cabin; supplying compressed air into the prechamber at
least partially filled with suspension, and opening a vent valve
connected to the pressure vessel, for example which is a throttle
valve or a pressure relief valve. It is preferred that the method
encompass at least the following procedural step: Aspirating
suspension through the end of the return line connected to the
collection receptacle of the blasting cabin, in particular by
generating a vacuum in the prechamber and/or turning on a pump
arranged between the collection receptacle and prechamber, and
opening a vent valve connected to the prechamber; as this takes
place, supplying compressed air to generate overpressure in the
pressure vessel at least partially filled with suspension; and,
given an overpressure in the pressure vessel, at least
intermittently opening the valve allocated to the feed line so as
to blast suspension onto one or several workpieces.
[0029] It is preferred that the method encompass at least the
following: Turning off the compressed air supply in the pressure
vessel; generating overpressure in the prechamber by supplying
compressed air into the prechamber; given an overpressure in the
prechamber, at least intermittently opening the valve allocated to
the feed line, and blasting suspension onto one or several
workpieces, and in particular at least intermittently opening a
vent valve connected to the pressure vessel. In a preferred further
development, the method encompasses at least the following
procedural steps: Generating overpressure in the pressure vessel by
supplying compressed air into the pressure vessel and opening the
valve allocated to the bypass line, so that at least the liquid
phase of the suspension or the suspension is transported from the
pressure vessel into the prechamber; once a specific level has been
reached in the prechamber, ending, in particular automatically
ending, the supply of compressed air into the pressure vessel and
generating overpressure in the prechamber by supplying compressed
air, and in the process at least intermittently opening a vent
valve connected to the pressure vessel and/or opening the valve
allocated to the feed line for blasting suspension out of the
blasting device. Alternatively or additionally, it is preferred
that the suspension be blasted onto one or several workpieces,
wherein the weight ratio between the overall solid phase contained
in the suspension and the overall liquid phase contained in the
suspension is greater than 0.5, in particular greater than 0.9, and
in particular has the value 1.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention will be described in more detail below with
reference to the attached drawings, which show preferred exemplary
embodiments. Shown therein on:
[0031] FIG. 1 is a schematically simplified view of a device
according to the invention in a first preferred exemplary
embodiment;
[0032] FIG. 2 is a schematically simplified view of a device
according to the invention in a second preferred exemplary
embodiment, in a preferred procedural step;
[0033] FIG. 3 is the device according to FIG. 2, in another
preferred procedural step;
[0034] FIG. 4 is the device according to FIG. 2, in another
preferred procedural step;
[0035] FIG. 5 is the device according to FIG. 2, in another
preferred procedural step;
[0036] FIG. 6 is the device according to FIG. 2, in another
preferred procedural step;
[0037] FIGS. 7-7a are sectional views through a check valve, which
corresponds to the check valves depicted on FIG. 1-6;
[0038] FIG. 8 is a sectional view along sectional plane VIII-VIII
on FIG. 7;
[0039] FIG. 9 in an exploded view are components of the check valve
depicted on FIG. 7;
[0040] FIG. 10 is a perspective magnified cutout of cutout X on
FIG. 7;
[0041] FIG. 10a is a perspective magnified cutout according to FIG.
10, but after the guiding lamellae have been fastened;
[0042] FIG. 11 is a sectional view of the check valve comparable to
FIG. 7 in an open position;
[0043] FIG. 12 is a sectional view comparable to FIG. 11, while
transitioning from the open to the closed position;
[0044] FIG. 12a is a magnified cutout of detail XII on FIG. 12;
[0045] FIG. 13 is a sectional view similar to FIG. 11, 12, but with
the check valve in the closed position;
[0046] FIG. 14 is a cutout of a device according to the invention
in another preferred exemplary embodiment, magnified in comparison
to FIGS. 1 to 6, and
[0047] FIG. 15 is another preferred exemplary embodiment of a
device according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0048] Introduced with regard to FIG. 1 is a first preferred
exemplary embodiment of a device 1 according to the invention. The
device serves to blast suspension onto one or several workpieces,
wherein the flowable suspension used for workpiece blast treatment
is not also shown on FIG. 1. A workpiece 19 and its workpiece
receptacle 18 are denoted by dashed lines, since they are not part
of the device. The device 1 encompasses a pressure vessel 2 for
holding suspension, and a feed line 3 connected to the pressure
vessel 2, whose end remote from the pressure vessel 2 is connected
to a blasting device 4, for example a blasting gun. Reference
number 4' denotes a nozzle holder, which on its part can be
immovably fixed to a preferably adjustable bracket (not also
shown). The feed line 3 encompasses a riser pipe 5 and a flexible
tube 6, between which a valve 7 is switched (i.e., interposed). The
housing of the pressure vessel 2 has a pressure-tight design. The
riser pipe 5 extends from the top through a pressure-tight terminal
in the cover 8 vertically downward, wherein the distance between
the mouth 9 of the feed line 3 and the lowest point of the pressure
vessel measures less than one fourth of the height of the interior
of the pressure vessel 2. The device 1 encompasses a prechamber 10
for the suspension. The latter has a pressure-tight housing, and is
situated underneath the pressure vessel 2. The prechamber 10 is
connected to the pressure vessel 2 by a check valve 11 situated
between the respective terminals of the pressure vessel 2 and the
prechamber 10. The device 1 further encompasses a return line 12,
which is connected by means of another check valve 13 to a terminal
of the prechamber 10 on the bottom side, interposing the check
valve 13. A blasting cabin is marked 14. Just as the pressure
vessel 2, prechamber 10 (and other components yet to be mentioned),
the blasting cabin is shown in a simplified, cut view, thereby
making the interior visible. For example, the interior 15 of the
blasting cabin 14 can incorporate an adjustable, e.g., tripod-like
fixation means (not also shown on the figures) for the blasting
device, along with one or several workpiece receptacles 18 for one
or several workpieces 19, which are to be blasted with a
suspension. The interior 15 of the blasting cabin 14, which is also
referred to as blasting chamber, is enveloped by the blasting cabin
14 on all sides. It is bordered from below by a funnel floor 16,
which downwardly tapers. In the example, the bottom side of the
funnel floor 16 is connected to a cup-shaped receiving vessel 17',
which together with the funnel floor 16 yields a collection
receptacle 17 for the suspension. The suspension hitting the funnel
floor 16 can be accommodated by the funnel floor 16 even above the
receiving vessel 17', depending on quantity. The receiving vessel
17' is connected with the interior 15 so as to be upwardly open at
all times. The end 20 of the return line 12 remote from the
prechamber 10 is connected to the collection receptacle 17. In the
operating state, the suspension circulates through the described
components. It is possible for the blasting cabin 14 to be
integrated into the device 1 according to the invention, and for it
to be fixedly joined with the device 1, for example. Alternatively,
it is possible that the blasting cabin 14 not be integrated into
the device 1, but rather that the device 1 can optionally be
connected as an in particular modular, autonomous unit to one or
various blasting cabins 14 as required, or detached therefrom.
[0049] During operation of the arrangement shown on FIG. 1,
suspension gets out of the pressure vessel 2 through the feed line
3 and blasting device 4 into the interior 15 of the blasting cabin
14, and can there be blasted onto a workpiece 19 accommodated by
the workpiece receptacle 18 for grinding the workpiece surface. The
suspension is composed of solid, finely dispersed blasting agent
and, for example, water, and is here preferably blasted onto the
workpiece surface as a liquid jet for grinding the latter. In this
regard, the device 1 according to the invention could also be
referred to as a liquid jet grinding system, i.e., as a system for
grinding by means of a liquid jet. The suspension then accumulates
in the collection receptacle 17, and can from there be transported
through a valve 13 into the prechamber 10, from where the
suspension can again be transported back into the pressure vessel 2
through the valve 11.
[0050] The device 1 encompasses a compressed air terminal 22, which
is centralized in the example, and serves to supply the device 1
according to the invention with compressed air. To this end, for
example, the compressed air terminal can be connected to an
external compressed air supply line or, for example, directly to a
compressed air source (e.g., to a compressor), which either belongs
to the device 1 according to the invention or is not integrated
into the latter. The device 1 encompasses a pneumatic line 21, in
which a valve 23 is placed, and which is connected to the
compressed air terminal 22 by means of a regulator unit 24. The
pneumatic line 21 is connected to the pressure vessel 2 on its
upper side. The pressure vessel 2 is pressure-tight in design, so
that it can be exposed to a pressure freely selectable with the
regulator unit 24 with the valve 23 open. For example, the valve 23
can be a two-way valve, which can optionally be opened or closed.
During operation, the suspension as a rule does not fully take up
the interior of the pressure vessel 2, so that an air cushion forms
above the suspension, and dynamically adjusts to a varying level of
suspension in the pressure vessel 2, so that the same pressure set
with the regulator unit 24 always acts on the suspension during
pressurization. The device 1 also encompasses a pneumatic line 25
and a valve 26 placed therein, by means of which the prechamber 10
is connected to the compressed air terminal 22. In the example, the
upper side of the prechamber 10 has connected to it a line 27,
whose other end is connected to a crossing 28. In the example
(i.e., not necessarily), the crossing 28 has four line terminals,
which are connected with each other, permanently open. The mutually
open connection is symbolically denoted by a point. One end of the
line 25 is connected to the crossing 28, and the other end to a
line junction 29, from which the line 21 also branches, and which
is connected with the compressed air terminal 22 with the regulator
unit 24 interposed. The line 21 has placed into it a line junction
30 from which a throttle valve 31 branches. A vent valve 32 is
connected to the prechamber 10. The vent valve 32 can be optionally
opened or closed by means of a valve 33 connected thereto, which in
this regard can also be referred to as a control valve. In the
example, the vent valve involves a known, so-called pinch valve.
The valve 33 used to control the latter is located in a line 34
that is connected to the vent valve 32, and branches away from a
line 35 that is connected to the compressed air terminal 22 with an
additional regulator unit 36 interposed. If the valve 33 is opened,
compressed air flows into the vent valve 32, thereby closing the
latter. By contrast, if the valve 33 is moved into a switch
position that allows air to flow out of the pinch valve through a
vent terminal of the valve 33, the vent valve 32 is opened. The
valve 33 is preferably a three-way valve.
[0051] The device 1 encompasses a vacuum generating device 37,
which is connected to the prechamber 10 by means of a line 38 and
by means of a valve 39. In the example, the vacuum generating
device 37 involves a vacuum injector. In the example, the line 38
is connected to a terminal of the crossing 28, and thereby
connected to the prechamber. The vacuum generating device 37
functions based on the Venturi principle in the example. The vacuum
generating device 37 is connected by means of a line 40 that
incorporates a valve 41 and by means of an additional regulator
unit 42 with a pressure supply line 43, which extends from the
compressed air terminal 22, and from which the regulator units 24
and 36 also branch in the example (also not necessarily). For
example, the valve 41 can be a two-way valve, which can optionally
be opened or closed. If the valve 41 is opened, compressed air
flows through the vacuum generating device 37 into the environment,
which creates negative pressure in the line 38. The valve 39 also
involves a pinch valve in the example. Connected to the latter for
control purposes is a line 44, which in the example branches away
from the line 35, and in which is placed a valve 45, a three-way
valve in the example. If the valve 45 is opened, compressed air
flows into the valve 39 (i.e., into the pinch valve), which is
thereby closed. On the other hand, if the valve 45 is moved to a
valve position in which air can escape from the valve 39 into the
environment through the line 44 and through a vent terminal of the
valve 45, the valve 39 is opened, thereby resulting in an open
connection between the prechamber 10 and vacuum generating device
37.
[0052] The valve 7 also involves a pinch valve in the example.
Connected thereto for control purposes is a line 46 with valve 47
placed therein for control purposes. The line 46 is connected with
the compressed air terminal 22, with the regulator unit 36
interposed. The valve 47 involves a three-way valve in the example.
If the latter is opened, compressed air flows into the valve 7,
which is thereby closed. On the other hand, if the valve 47 is
moved into a valve position in which air can escape from the valve
7 into the environment through the line 46 and through a terminal
of the valve 47 serving as a vent, the valve 7 is opened.
[0053] The device 1 encompasses a bypass line 48 for a suspension
and a valve 49 situated therein. The one end 50 of the bypass line
58 discharges into the interior of the pressure vessel 2. In the
example, the pressure vessel 2 has an ascending sifter 51 placed
into it from above, into which the bypass line 48 enters from
above. The bypass line 48 leads pressure-tight through the wall of
the prechamber, and its corresponding end 52 discharges into the
interior of the prechamber 10. In the example, the valve 49 also
involves a pinch valve. For control purposes, the latter is also
connected to a line 53, into which is placed a valve 54, a
three-way valve in the example, and which in the example is
connected with the compressed air terminal 22, with the regulator
unit 36 interposed. If the valve 54 is opened, compressed air flows
into the valve 49, so that the latter is closed. On the other hand,
if the valve 54 is switched to a valve position in which air can
flow out of the valve 49 and into the environment through the line
53 and through a terminal of the valve 54 serving as a vent, the
valve 49 is opened.
[0054] In the example, the regulator units 24, 36 and 42 each
involve a pressure regulating valve. For example, a proportional
valve can be involved. An air pressure can be set on the regulator
unit 24 and used to pressurize the interior of the pressure vessel
2 and/or the interior of the prechamber 10, depending on the
position of the valves 23 and 26. As will be explained below, the
regulator unit 24 can be used to set or regulate the jet pressure
with which the suspension is pressed out of the blasting device as
a jet, i.e., blasted. For example, the valves 23, 26 involve
two-way valves. As described, the valves 33, 45, 47 and 54 serve to
pre-control the valves 32, 39, 7 and 49, which each involve a pinch
valve. The pressure of the compressed air with which the pinch
valves are actuated can be set or regulated by means of the
regulator unit 36. The valve 41 can once again involve a two-way
valve, for example. The regulator unit 42 can be used to set or
regulate the pressure of the compressed air flowing through the
vacuum generating device 37 with the valve 41 open.
[0055] It goes without saying that the described terminals of the
pressure vessel 2 and prechamber 10 are outwardly pressure-tight in
design on their respective housing. Secured to the pressure vessel
2 is a level sensor 55, so as to detect when the fill level of
liquid or suspension has dropped below a specific level. Secured to
the prechamber 10 in its lower half is a level sensor 56, so as to
detect when the suspension or liquid has dropped below a specific,
minimal level. In addition, the prechamber 10 has secured to it an
upper level sensor 57, so as to detect when the suspension or
liquid has exceeded a specific upper level. In order to automate
the device 1, the valves 23, 26, 31, 33, 41, 45, 47 and 54 in the
example involve electric valves, i.e., valves that can be
electrically switched between the different valve positions. These
valves and the level sensors 55-57 are connected with a controller
of the device 1 (in a manner not shown on the figures). Marked 58
is a sensor connected to the receptacle 17, which detects the
presence of the suspension, and can also be connected to the
controller.
[0056] The valve 11' between the pressure vessel 2 and prechamber
10 involves a check valve 11, which is only schematically depicted
on FIG. 1, and will be described in greater detail with reference
to FIG. 7-13, which have been magnified by comparison. As
illustrated by the cutouts in the sectional view on FIG. 7, the
check valve 11 in the installation position shown is connected at
its upper terminal 59 to a pressure vessel terminal 60, which
discharges into the pressure vessel 2 through the floor 61 of the
pressure vessel 2 at the lowest point of the floor 61. At its other
lower terminal 62 in the depicted installation position, the check
valve 11 is connected to the prechamber 10 by means of a riser pipe
63, only the upper section of which is shown on FIG. 7. The riser
pipe 63 is guided pressure-tight through the closed upper side of
the prechamber 10 into its interior, wherein the lower, open end 64
of the riser pipe 63 is located only a slight distance over the
lowest point of the prechamber 10. The passage direction 65 of the
check valve 11 is denoted with an arrow on FIG. 7. The latter is
directed from the prechamber 10 to the pressure vessel 2, and the
locking direction of the check valve 11 is directed oppositely
thereto from the pressure vessel 2 to the prechamber 10. As shown
in further detail on FIG. 7-13, the check valve 11 encompasses a
sealing element 66, which is conical in the example, and a valve
sleeve 67, which preferably consists of a material that is less
easily deformable by comparison to the sealing element 66. The
valve sleeve 67 is placed in a valve housing 68. The valve sleeve
67 envelops a passage opening for a suspension to flow through. Its
inwardly facing surface runs cylindrically in a longitudinal
section 69. In a longitudinal section that adjoins the latter in
the passage direction 65 and is situated at the top in the
installation position, the valve sleeve 67 forms a seal seat 70
that conically expands in the passage direction 65. The sealing
element 66 forms a sealing edge 71 that extends along its
circumference.
[0057] FIG. 11 shows the check valve 11 in an open position, in
which the sealing element 71 is spaced apart from the seal seat 70,
so that the suspension 72 denoted by arrows can flow through the
check valve 11 in the passage direction 65. If the sealing element
66 is moved in the direction toward the seal seat 70 proceeding
from this open position, initially only the sealing edge 71 of the
sealing element 66 comes into contact with the seal seat 70 along a
circle 73, as illustrated on FIG. 12. The sealing edge 71 is
bordered by two surfaces 74, 75 of the sealing element 66, which in
a cross section oriented transversely to its circumferential
direction (see FIG. 12a) run at a right angle to each other, and
which each include a respectively acute angle .alpha. or .beta.
with the surface of the seal seat 70 in this cross section. As also
depicted on FIG. 12, when moved from the open position toward the
seal seat 70, the sealing edge 71 of the sealing element 66 hits an
annular zone spaced apart from the tapered end of the seal seat 70.
Proceeding from the state shown on FIG. 12, if the sealing element
66 is exposed to a pressure P opposite the passage direction 65,
the latter triggers an elastic deformation of the sealing element
66 in the area of its sealing edge 71, as a result of which the
sealing element 66 then abuts flat against the seal seat 70 along
its circumference, as illustrated on FIG. 13. The check valve 11 is
closed in this position. If the sealing element 66 is subsequently
removed from the valve sleeve again in the passage direction 65,
its outer circumference resiliently deforms back into the shape
depicted on FIG. 11.
[0058] As relates to the selected exemplary embodiment of the check
valve, for example, FIGS. 7 and 9 show in further detail that the
sealing element 66 exhibits a passage opening 76, into which a
sleeve 7 is adhesively bonded or pressed, for example. The surface
78 of the sealing element pointing opposite the passage direction
65 runs flatly and transversely to a geometric longitudinal central
axis 79 of the check valve 11. A fastening plate 80 abuts against
the lower surface 78, and has a nut 82 aligned flush with its
central borehole 81, which is secured to the fastening plate 80,
for example. Four passage openings 83 each spaced apart by
90.degree. relative to each other in the circumferential direction
extend through the fastening plate 80 near the edge. The latter are
used for fastening two respective plate-shaped guiding lamellae 84,
85. The guiding lamellae 84, 85 have edge contours that are
essentially identical to each other. Proceeding from two lateral
projections 86, the radially outer edges 87 diminished a bit in
their lateral spacing extend parallel to each other, and transition
into a respective upper side 88, proceeding from which two
respective tongues 89 extend. The one guiding lamella 84 has a
central slot proceeding from the side with the projections 86, and
the other guiding lamella 85 is slotted proceeding from the
opposing side, so that the two guiding lamellae 84, 85 can be
plugged together in the mutually orthogonal position depicted on
FIG. 9, so that their edges align flush with each other during a
rotation around the longitudinal central axis 79 as viewed in
projection. In order to secure the assembled guiding lamellae 84,
85 to the fastening plate, a respective pair of the tongues 89 can
be inserted through a respective passage opening 83 (see FIG. 10),
and therein be outwardly bent to achieve a positive fit (see FIG.
10a). The fastening plate 80 can then be secured to the sealing
element 66 by means of a screw 90, which is inserted through the
sleeve 77 and screwed by the nut 82. The guiding lamellae 84
comprise guiding means, which, e.g., as illustrated on FIG. 8, are
left in the valve cross section of several flow-through openings
91, and whose radially outer edge 87 forms a longitudinal guide
with the inwardly pointing cylindrical surface of the valve sleeve
67 in its longitudinal section 69. The latter allows the sealing
element 66 and guiding lamellae 84 to move relative to the valve
sleeve 67, concentrically and parallel to the longitudinal axis 79.
The relative movement is limited in the passage direction 65 if the
radial projections 86 run against an annular surface of the valve
sleeve 67.
[0059] In the selected example, an installation position is
selected for the check valve 11 in which the longitudinal central
axis 79 runs vertically, and the sealing element 66 points
upwardly. During operation of the device 1, the sealing element 66
shifts automatically relative to the immovably mounted valve sleeve
67 as a function of the pressures and forces acting on the sealing
element 66. Therefore, the valve need not be separately actuated.
If the pressure in the prechamber 10 is greater than the pressure
in the pressure vessel 2, the pressure difference produces a
resultant compressive force that acts on the sealing element 66 in
the passage direction 65. If the latter is greater than the
opposing weight of the movable valve parts, the sealing element 66
with the valve components fastened thereto is upwardly displaced
relative to the valve sleeve 67 into the open position shown on
FIG. 11, in which further movement is prevented by the projections
86. As a result of the pressure difference, the suspension denoted
with arrows on FIG. 11 then flows through an annular passage that
envelops the sealing element 66. If the pressure in the prechamber
10 corresponds to the pressure in the pressure vessel 2, the
sealing element 66 with the components connected thereto sinks
downwardly owing to gravitational force, wherein it only linearly
abuts against the seal seat 70 in the manner shown on FIG. 12 given
a deformability of the sealing element 66 that has been suitably
adjusted to the weight of the movable valve parts. Any blasting
agent that has been deposited onto the seal seat 70 is expelled
from the continuous sealing edge 71 of the sealing element 66 as
the latter sinks downward, and the blasting agent located
underneath the sealing element 66 sinks downward along the seal
seat 70. If the pressure in the pressure vessel 2 is greater than
the pressure in the prechamber 10, the pressure and weight together
act downward. Depending on the level of the pressure difference,
the sealing element 66 can deform at its radially outer edge in the
manner shown on FIG. 13, so that a tight abutment of the sealing
element 66 comes about along the circumference, with the latter
extending over a certain width in a cross section lying transverse
to the circumferential direction. In the example on FIG. 13, a
planar, conical contact zone or sealing zone results, wherein the
check valve 11 is in the closed position.
[0060] In the exemplary embodiment shown on FIG. 1 (and also in the
examples according to FIGS. 2, 14 and 15), the check valves 11 and
13 are structurally identical. The check valve 13 (see FIG. 7a) is
also situated in such a way that its longitudinal central axis 96
runs vertically. The upper terminal 93 of the check valve 13 is
connected to a prechamber terminal 94, which discharges into the
prechamber 10 through the floor 95 of the prechamber 10 at its
lowest point. At its lower terminal 97, the check valve 13 is
connected to the return line 12. A comparison of FIGS. 7 and 7a
reveals that the two check valves 11, 13 are structurally
identical. For simplification purposes, the displaceable valve
components are labeled with the same reference numbers for both
check valves 11, 13. The installation position is also selected in
such a way for the check valve 13 that the sealing element 66 is at
the upper valve end, i.e., that it abuts downwardly against the
seal seat 70 in the closed position. As a consequence, the passage
direction 98 (as with the check valve 11) is upwardly directed for
the check valve 13 as well.
[0061] In the example on FIG. 1, the floor 61 of the pressure
vessel 2 and the floor 95 of the prechamber 10 are made out of
sheet metal and conically shaped, so that the cross section of the
pressure vessel 2 or prechamber 10 tapers downwardly. The check
valve 11 is outwardly sealed pressure-tight from below at the
lowest and narrowest cross section of the floor 61, as is the check
valve 13 from below at the lowest and narrowest cross section of
the floor 95. As shown on FIGS. 7 and 7a, the outer diameter of the
annular flow cross section formed in the check valve corresponds to
the outer diameter of the respective funnel-shaped floor present at
the terminal in the example with the valve in the open
position.
[0062] In the example on FIG. 1, the device encompasses a cyclone
separator 99. The latter is used to separate out of the suspension
fines that can be separated out by means of the ascending sifter.
Such fines can arise during operation over time due to a certain
wear of the blasting agent, and potentially also as erosion from
machined workpieces, and become concentrated in the suspension over
time. Such fines can be separated out in the ascending sifter 51 in
that they rise higher than the blasting agent during a very slow
upward flow. A smaller partial flow of liquid can be diverted at
the top of the ascending sifter 51, and fed to the cyclone
separator 99 through a line 100. Purified liquid can be passed
through another line 101 into the blasting cabin 14, and thus fed
back to the circulation. The ascending sifter 51 is a pipe that is
open. The overpressure prevailing in the pressure vessel 2 during
operation causes the liquid in the ascending sifter 51 to rise
according to the quantity flowing off above, on the one hand
through the terminal 102 for rinsing the workpieces, and on the
other hand diverted into the cyclone separator 99 through the
terminal 103. If necessary, liquid can be tapped at the terminal
102 for rinsing already blasted workpieces. The liquid tapped there
has risen through the entire height of the ascending sifter 51, and
thus contains practically no blasting agent or suspended particles.
The liquid diverted to the cyclone separator 99 is removed through
the riser pipe 104, which is also integrated into the bypass line
48, at roughly half the height of the ascending water column, i.e.,
in a region where hardly any blasting agent is present, but
suspended particles still are. The quantity of liquid diverted to
the cyclone separator 99 is preferably slight, but can measure
approx. 0.5 to 3 liters per minute, depending on the type of plant.
The diverted quantity of liquid determines the rate of ascension in
the ascending sifter 51; therefore, it should preferably be
possible to exactly determine it. A throttle plate is built into
the screw connection at the upper outlet of the cyclone separator
99, i.e., in its pure water area. Throttle plates with varying
boreholes enable an exact and permanent determination of flow rate.
The cyclone separator 99 is exposed to the same pressure as the
pressure vessel 2. This also facilitates the draining of sludge
with a hand valve 106 provided for this purpose. An exchangeable
nozzle 107 is provided at the inlet of the liquid into the cyclone
separator 99. The liquid flowing into the cyclone separator 99 must
have a certain speed so as to impart rotation to the water column.
The hand valve 108 can be used to operatively detach the cyclone
separator 99 from the remaining device 1.
[0063] FIGS. 2 to 6 show a device 1 according to the invention in a
second preferred exemplary embodiment, and illustrate a preferred
exemplary embodiment of the method according to the invention. The
device depicted on FIG. 2-6 corresponds with the exemplary
embodiment shown on FIG. 1, except for the cyclone separator 99,
which is not present in the example on FIGS. 2 to 6. A feed line 3
with a valve 7 leads from the pressure vessel 2 to a nozzle holder
4' and a blasting device 4 (e.g., a blasting gun). As in the other
exemplary embodiments, several feed lines 3, e.g., each with one
valve and each with one blasting device, could branch from the
pressure vessel 2.
[0064] Suspension 72 present in the pressure vessel 2 is pressed
out of the blasting device 4 with the pressure prevailing in the
pressure vessel 2. The feed line 3 encompasses the hose 6 and riser
pipe 5 connected thereto. The riser pipe 5 passes from above
through a wall of the pressure vessel 2, and extends vertically
downward therein. Its downwardly open mouth 9 is located in a lower
region of the interior of the pressure vessel 2, in the area of the
funnel-shaped floor 61 in the example. During operation, the level
probe 55 can be used to ensure that the downwardly open mouth 9 of
the feed line is always immersed in the suspension 72, specifically
in a container region in which a through mixing of the suspension
is always ensured during operation. As illustrated by the following
description, the structural design of the device 1 allows the
operating process in which suspension is blasted onto one or more
workpieces 19 to run independently of the processes in the pressure
vessel 2, e.g., independently of the respective level of the
suspension in the pressure vessel 2. The blasting process can thus
run permanently, i.e., if needed over a prolonged period without
interruption, or also in intervals. In order to ensure a continuous
operation, the suspension in the blasting cabin 14 that exits the
blasting device 4 (e.g., a blasting gun) must be returned to the
pressure vessel 2 again. To this end, the prechamber 10 is provided
underneath the pressure vessel 2, and connected to the return line
12 hooked up to the collection receptacle. A respective one of the
check valves 11 or 13 already described with reference to FIG. 7,
7a with a passage direction pointing from the bottom up is arranged
or interposed between the pressure vessel 2 and prechamber 10 (on
the one hand) and between the prechamber 10 and return line 12 (on
the other). The check valves 11, 13 selected in the exemplary
embodiment are specially constructed to prevent a liquid that
exhibits a large percentage of abrasive solids (in particular
blasting agent) from flowing back. In a very cost-effective manner
and without requiring special control measures, these check valves
ensure that a flowing direction can only be from the bottom up. The
suspension diverted by the feed line 3 from the pressure vessel 2
can be replaced in batches from below out of the prechamber 10.
This influx from below, i.e., opposite the sinking direction of
heavy particles in the suspension, enables the achievement of a
very uniform and constant mixing of liquid and the solids therein.
This can eliminate the need for additional measures, such as
agitators.
[0065] Alternatively, it would be possible to install (e.g.,
pneumatically or electrically) controllable valves, e.g., pinch
valves, instead of the check valves 11, 13. Since activation is
required for opening and closing such valves as needed, this would
necessitate a greater outlay. In addition, pneumatic pinch valves
would open given a compressed air supply failure, and allow the
suspension located above to drain uncontrollably.
[0066] FIG. 2 shows a preferred first procedural step of a method
according to the invention. This step serves to fill the device 1
with suspension 72, and is thus potentially no longer necessary
after a preceding operation of the device 1. The suspension 72 was
poured onto the funnel floor 16 of the blasting cabin, and
accumulates in the collection receptacle 17 for the suspension,
which in the example is comprised of a cup-shaped receiving vessel
17' and a funnel floor 16 that discharges therein from above.
[0067] FIGS. 2 to 6 indicate symbolically different switching and
operating states for the valves 23, 26, 31, 33, 41, 45, 47 and 54.
If one of the valves 23, 26, 31, 41 is marked "X", it means that
the valve is closed at this point in time, i.e., if not marked "X",
the valve is open. For the valves 33, 45, 47 and 54, an "X" means
that the valve in this state does not allow through any compressed
air supplied by the compressed air terminal 22 via the regulator
unit 36, but air that serves to control the respectively connected
pinch valve can flow back from the pinch valve and escape into the
environment through the respective valve 33, 45, 46 or 54. If a
valve 33, 45, 47 or 54 is not marked "X", the respective valve is
open at this point in time, so that inflowing compressed air from
the compressed air terminal 22 is allowed through to the connected
pinch valve. No such designation is made for the pinch valves 7,
32, 39 and 49, which can be pneumatically closed or opened, since
they are always closed when the pneumatic line controlling them is
exposed to compressed air, and on the other hand opened when the
pneumatic line controlling them is vented. Therefore, the valve
position results from the designated position of their control
valve. During the procedural step 2 shown on FIG. 2, the vacuum
generating device 37 is activated by means of the open valve 41.
The valve 39 is opened, and the valves 26 and 32 are closed, so
that the vacuum generating device 37 inside of the prechamber 10
generates a vacuum, i.e., a pressure lying under the ambient
pressure. As a result, the pressure in the prechamber 10 is lower
than in the pressure vessel 2, so that the check valve 11 is
automatically closed. The pressure inside of the prechamber 10 is
also lower than the pressure in the collection receptacle 17, so
that the check valve 13 automatically opens. The vacuum causes
suspension 72 to be siphoned upwardly into the prechamber 10 from
the collection receptacle 17 through the return line 12 and through
the check valve 13. Because the suspension enters into the
prechamber 10 from below, i.e., against the force of gravity, the
suspension 72 is continuously mixed in the prechamber 10. A
negative pressure of approx. 100 to 200 cm water column may be
sufficient to aspirate the suspension through the return line 12.
The latter can be generated in various ways. In the vacuum
generating device 37 schematically depicted on FIG. 3, the example
involves a pneumatic injector. However, this task can instead also
be handled by a vacuum pump or, for example, a blower. Since a
pulsed application is involved, and the negative pressure is
slight, a pneumatically, hydraulically or mechanically activated
bellows would also be possible, for example, as would a
pneumatically, hydraulically or mechanically activated piston pump.
If the level in the prechamber 10 reaches the level probe 57, the
described aspiration process is ended, and the negative pressure in
the prechamber 10 can be automatically switched over to
overpressure.
[0068] FIG. 3 shows a preferred procedural step with which the
suspension can be upwardly pumped out of the prechamber 10 into the
pressure vessel 2. To this end, the aspiration of suspension from
the collection receptacle 17 into the prechamber 10 was first
ended. While the valves 32 and 39 are closed, compressed air is
guided through the open valve 26 into the prechamber 10 partially
filled with suspension 72, so as to generate overpressure inside of
the prechamber 10, i.e., pressure lying over the ambient pressure,
which bears down on the suspension 72. The vent valve 31 (a
throttle valve in the example) connected to the pressure vessel 2
is here open. Since the pressure in the prechamber 10 thus exceeds
the pressure in the pressure vessel, the check valve 11 opens
automatically. As a result, suspension 72 is upwardly pumped out of
the prechamber 10 into the pressure vessel 2 from below through the
riser pipe 63 and through the check valve 11. Since the suspension
72 enters the pressure vessel 2 from the bottom up, this causes the
suspension to be continuously mixed in the pressure vessel 2. While
upwardly pumping the suspension into the pressure vessel 2, its
vent valve 31 is open, so that air can escape from the latter. If
the level of the suspension 72 in the prechamber 10 has reached the
level probe 56 as the result of this "pumping process", the valve
26 and vent valve 31 close, and the valve 23 simultaneously opens.
In a preferred embodiment, the vent valve 32 also opens
simultaneously for one to two seconds. The extremely fast pressure
drop in the prechamber 10 prompts the check valve 11 to close
automatically. Cooling gives rise to condensate. Air diverted out
of the prechamber 10 can be diverted into the blasting chamber,
i.e., into the interior of the blasting cabin 14. After a
prescribed period of time, the vent valve 32 can again close, and a
switch can again be made to the suction operation depicted on FIG.
2, for example, provided the sensor 58 relays a message that
suspension 72 is present in the collection receptacle 17. The
direction of the arrows situated over the surface of the suspension
72 schematically denotes whether the level is rising or falling (as
also the case for the remaining figures).
[0069] FIG. 4 shows another preferred step during the
implementation of a method according to the invention. During this
procedural step, suspension 72 is blasted onto a workpiece 19 from
the blasting device 4 (e.g., blasting nozzle), so that the fill
level of the pressure vessel 2 drops, while suspension 72 is
simultaneously upwardly aspirated out of the collection receptacle
17 into the prechamber 10. In the example, upward aspiration takes
place as in the procedural step described for FIG. 2. In order to
press suspension 72 out of the pressure vessel 2 through the
blasting device 4 during this time, an overpressure is generated in
the pressure vessel 2 by introducing compressed air through the
open valve 23. As a consequence, the pressure in the pressure
vessel 2 is greater than in the prechamber 10, so that the check
valve 11 is automatically closed. On the other hand, the pressure
in the prechamber 10 is also less than the pressure in the
collection receptacle 17, so that the check valve 13 automatically
opens. The valve 7 is opened for the desired duration so as to
press suspension 72 out of the blasting device 4, i.e., for the
blasting process.
[0070] FIG. 5 shows another preferred step during implementation of
the method according to the invention. It is here possible to
simultaneously press the suspension out of the blasting device 4
and transport the suspension 72 from the prechamber 10 into the
pressure vessel 2. To this end, the compressed air supply into the
pressure vessel 2 was ended by closing the valve 23, while instead
opening the valve 26, so that compressed air is now pressed into
the prechamber at the same pressure, and an overpressure is
generated therein. This causes the check valve 13 to close
automatically. Since the vent valve 31 of the pressure vessel 2 is
opened, the pressure in the prechamber 10 rises in excess of the
pressure in the pressure vessel 2, so that the check valve 11
automatically opens. As a consequence, the overpressure generated
in the prechamber 10 upwardly presses suspension 72 out of the
prechamber 10 into the pressure vessel 2. The vent valve 31, which
in the example is a throttle valve, is selected in such a way that
a pressure higher by comparison to the ambient pressure is also
retained in the pressure vessel 2. This pressure can be somewhat
lower than or equal to the pressure in the prechamber 10. The vent
valve 31 could also involve a pressure relief valve, for example.
The latter could limit the pressure in the pressure vessel 2 to 3
bar, for example. The pressure generated by supplying compressed
air into the prechamber 10 could measure 3 bar or somewhat more
than 3 bar, for example, wherein it is understood that pressures
deviating from this numerical example would also be possible.
Depending on how large the pressure drop from the prechamber 10 to
the pressure vessel, suspension is upwardly pumped from the
prechamber 10 into the pressure vessel 2. In order to allow this
suspension volume flow to exceed the suspension volume flow
dispensed by the blasting device 4, in particular averaged over
time, the vent valve 31 of the pressure vessel can be opened.
During the procedural step depicted on FIG. 5, the compressed air
routed into the prechamber 10 thus carries out a dual function. On
the one hand, it causes suspension 72 to be upwardly pumped into
the pressure chamber 2, and also causes suspension to be pressed
out of the blasting gun.
[0071] FIG. 6 shows another preferred step in implementing the
method according to the invention. This procedural step can be used
in particular after the operation of the device 1 was interrupted
for a certain period of time (e.g., for several minutes). Given
such an interruption, the heavy, solid particles in the suspension
72 begin to sink, thereby initiating a segregation. In order to
sustain the operating mixture, the device 1 can be switched to the
circulation mode shown on FIG. 6, in particular automatically,
given an operational interruption of a prescribed duration. Also
possible is to activate the circulation mode in adjustable
intervals, e.g., lasting 2 minutes or longer, depending on the used
blasting agent. Opening the valve 49 diverts liquid with only a few
solids out of the upper region of the pressure vessel 2 or out of
the ascending sifter 51 into the prechamber 10 through the bypass
line 48. If the liquid level in the prechamber 10 reaches its level
probe 57, a switch can again be made to another operating state,
e.g., to the operating state described for FIG. 3. Even after a
prolonged downtime of the device 1, e.g., for several weeks,
thorough mixing in the suspension 72 can again be smoothly achieved
by repeatedly, e.g., manually, switching the described circulation
process.
[0072] The blasting process results in a certain atomization of the
liquid. In order to keep the mixing ratio in a tolerable range and
not disrupt the operation of the device 1, liquid can periodically
be replenished. The level probe 55 of the pressure vessel 2
monitors a minimum level. Depending on the type of plant, a warning
is issued at too low a level, or a valve can be directly switched
to automatically compensate for the lost liquid until at least the
minimum level has again been reached.
[0073] Needless to say, several feed lines 3 can be connected to
the pressure vessel 2 as needed, to which one or several respective
blasting devices 4 can be connected.
[0074] In the example, the device encompasses a controller that is
connected with the described valves used for controlling the pinch
valves and with the level probes, which is adapted to set the
operating states described for FIG. 2-6 (or only selected operating
states from among the latter, as needed) in an automatic sequence
on the device.
[0075] FIG. 14 shows a cutout from a device 1 according to the
invention in another preferred exemplary embodiment. This device 1
once again also encompasses a pressure vessel 2, but, as opposed to
the examples on FIGS. 1 to 7, two prechambers 10, two return lines
12 and thus a total of four check valves 11, 13, which in the
example are all structurally identical in design, and correspond to
the valves depicted on FIG. 7, 7a. The two prechambers 10 are
connected to the pressure vessel 22 in parallel with each other,
each with a respective check valve 11 interposed. The floor 61 of
the pressure vessel 2 is conical in shape, and forms a downwardly
tapering funnel. Provided in the lower portion of the inclined
funnel wall are two passage openings, to which one of the check
valves 11 is connected on its upper side by means of a curved pipe
segment 109, wherein the passage direction 65 points up. The
respective floor 95 of the prechambers 10 is also conical in shape,
and forms a downwardly tapering funnel. A check valve 13 is
connected to the lowermost, and hence narrowest, cross section of
the floor 95 on its upper side, so that its passage direction 98
points up. The lower side of each check valve 13 is connected to a
respective return line 12, which at its respective other end can be
connected to a collection receptacle of a blasting cabin. The fact
that two prechambers 10 are present makes the plant a better
performing one by comparison to the above exemplary embodiments.
The advantage to the embodiment is that larger quantities of
suspension can be passed through the system, so that several or
larger blasting nozzles can thus be used. The prechambers 10
alternatingly enhance each other in their function. For example,
during operation, this makes it possible, while aspirating
suspension from the interior 15 of the blasting cabin 14 in the one
prechamber 10, to convey suspension into the pressure vessel 2 from
the other prechamber 10. The two prechambers 10 can alternate their
function with each other in specific time intervals. For example,
the switch can take place with only brief interruptions (e.g., of
about 2 seconds). A permanent flow of suspension 72 can be
achieved, both from the blasting cabin 14 into the prechambers 10,
and from the prechambers 10 into the pressure vessel 2. The fact
that there is a practically continuous influx of suspension from
below into the pressure vessel 2, which corresponds to the quantity
flowing away through the blasting device 4 or blasting nozzles,
ensures a lasting, optimal mixing of the liquid and blasting agent
in the suspension. In the example, a hand valve 110 is provided to
remove samples of the liquid-blasting agent mixture. When opening
the hand valve 110, the overpressure in the pressure vessel 2
presses suspension up through a riser pipe 111. The riser pipe 111
reaches down into the region of the pressure vessel 2, where the
suspension is drained through the mouth 9 of the riser pipe 5 from
the feed line 3 to the blasting device 4. This ensures that the
samples taken correspond to the mixture exiting the blasting device
4. It is preferred that all lines through which suspension flows be
open toward the bottom. As a consequence, given a prolonged
shutdown of the plant (e.g., for weeks), solids can downwardly sink
out of the lines, and no blockages can arise.
[0076] FIG. 15 shows a device 1 according to the invention in yet
another preferred exemplary embodiment. The device is designed
independently of a blasting cabin, but can be connected to a
blasting cabin for operation (e.g., to a blasting cabin of the type
depicted on FIGS. 1 to 7). The device 1 encompasses a housing 112,
which in the example can (i.e., does not have to) travel on wheels
113. Outwardly exiting the housing are a pneumatic line 114 for
connecting the compressed air terminal 22 with a compressed air
source (not also shown on FIG. 15), a portion of the feed line 3
with a blasting device 4 (e.g., blasting nozzle) potentially
connected thereto, and a longitudinal section of the return line
12. The feed line 3 and return line 12 are used for connection to a
blasting cabin. All remaining components of the device 1 are
located inside of the housing 112. In this regard, reference can be
made to an autonomous or modular construction of the device 1.
[0077] It goes without saying that a wide range of variations from
the described exemplary embodiments is possible for implementing
the invention. For example, individual or several of the described
components can be omitted (for example, the cyclone separator), or
replaced by other, in particular identically or similarly acting
components.
[0078] The above statements serve to explain the inventions
encompassed by the application as a whole, which further develop
the prior art least by way of the following feature combinations,
each taken separately, specifically:
[0079] A device 1, characterized in that a valve 11' between the
prechamber 10 and pressure vessel 2 is a check valve 11, that its
one, in particular upper, terminal 59 is connected to a pressure
vessel terminal 60 that discharges into the pressure vessel 2
through the floor 61 of the pressure vessel 2, in particular at its
lowest point, and that its other, in particular lower, terminal 62
is connected to the prechamber 10, wherein the passage direction 65
of the check valve 11 is directed toward the pressure vessel 2.
[0080] A device 1, characterized in that the device 1 encompasses a
vacuum generating device 37, in particular a vacuum injector or a
vacuum pump, to which the prechamber 10 is connected by means of at
least one line 38 and one valve 39, and/or that a pump is switched
between the prechamber 10 and return line 12, or a pump is
connected to the end of the return line 12 facing away from the
prechamber 10, wherein the conveying direction of the pump during
operation is directed toward the prechamber 10.
[0081] A device 1, characterized in that the device 1 encompasses a
valve 13' switched between the return line 12 and prechamber 10,
which involves a check valve 13, wherein this check valve 13 is
connected at its one, especially upper, terminal 93 to a prechamber
terminal 94, which discharges into the prechamber 10 through the
floor 95 of the prechamber 10, in particular at its lowest point,
and at its other, preferably lower, terminal 97 to the return line
12, and wherein the passage direction (98) of this check valve 13
is directed toward the prechamber 10, and wherein it is provided in
particular that this check valve 13 be structurally identical to
the check valve (11) switched between the prechamber 10 and
pressure vessel 2.
[0082] A device 1, characterized in that the floor 61 of the
pressure vessel 2 has a conical or curved shape, so that the cross
section of the pressure vessel 2 perpendicular to a vertical
direction tapers downwardly, and/or that the floor 95 of the
prechamber 10 has a conical or curved shape, so that the cross
section of the prechamber 10 perpendicular to a vertical direction
tapers downwardly.
[0083] A device 1, characterized in that the device 1 encompasses
at least one line 21 and one valve 23, with which the pressure
vessel 2 can be connected to a compressed air source separate from
the device 1, or with which the pressure vessel (2) is connected to
a compressed air source belonging to the device 1.
[0084] A device 1, characterized in that the check valve 11
switched between the prechamber 10 and pressure vessel 2 and/or the
check valve 13 switched between the return line 12 and prechamber
10 encompasses at least the following: A sealing element 66
comprised of an elastically deformable material and a valve sleeve
67, which forms a seal seat 70 that expands in the passage
direction 65 of the check valve 11, in particular conically,
wherein the sealing element 66 forms a sealing edge 71 extending
along its periphery, which when the sealing element 66 moves out of
an open position in a direction toward the seal seat 70 along the
sealing edge 71, in particular initially only along a circle 73,
comes into contact with the seal seat 70.
[0085] A device 1, characterized in that the sealing edge 71 is
bordered by two surfaces 74, 75 of the sealing element 66, which in
a cross section oriented transverse to its circumferential
direction run inclined to each other, in particular at a right
angle to each other, wherein both surfaces of the sealing element
66 each include an acute angle .alpha., .beta. with the surface of
the seal seat 70 in a cross section perpendicular to the
circumferential direction of the sealing edge 71.
[0086] A device 1, characterized in that the sealing element 66 is
accommodated in a longitudinally displaceable manner in the valve
sleeve 67 parallel to its longitudinal central axis 79, to which
end the sealing element 66 is connected in particular with guiding
means that leave one or several flow-through openings 91, and on
their radially outer edge 87 form a longitudinal guide with an
inwardly pointing cylindrical surface of the valve sleeve 67.
[0087] A device 1, characterized in that, when moved from an open
position toward the seal seat 70, the sealing edge 71 of the
sealing element 66 hits an annular zone of the seal seat 70 spaced
apart from the tapered end of the seal seat 70, and that
pressurizing the sealing element 66 against the seat seal 70
triggers an elastic deformation of the sealing element 66, as a
result of which the sealing element 66 abuts flat against the seal
seat 70 along its circumference.
[0088] A device 1, characterized in that the feed line 3 extends
through the wall of the pressure vessel 2 into its interior,
wherein the distance between the mouth 9 of the feed line 3 and
lowest point of the pressure vessel 2 measures less than half, in
particular less than one fourth, in particular less than one
eighth, of the height of the interior of the pressure vessel 2.
[0089] A device 1, characterized in that the check valve 11
switched between the prechamber 10 and pressure vessel 2 is
connected to a riser, in particular a riser pipe 63, at its lower
terminal in the installation position, which extends through the
upper side wall of the prechamber 10 into its interior, wherein the
distance between the lower opening 64 of the riser and the lowest
point of the prechamber 10 measures less than half, in particular
less than one fourth, in particular less than one eighth, of the
height of the interior of the prechamber 10.
[0090] A device 1, characterized in that the device 1 encompasses a
bypass line 48 and a valve 49 accommodated therein, wherein the one
end 50 of the bypass line 48 discharges into the interior of the
pressure vessel 2, in particular at more than half or three fourths
of its height, in particular inside of an ascending sifter 51
placed in the pressure vessel 2, and wherein the other end 52 of
the bypass line 48 discharges into the interior of the prechamber
10, in particular at less than half or one fourth of its
height.
[0091] A device 1, characterized in that the device 1 encompasses
two prechambers 10, two return lines 12 and four, in particular
structurally identical, check valves 11, 13, that the prechambers
10 are connected in parallel with each other and, interposing a
respective check valve 11, with the pressure vessel 2, and that a
respective return line 12 is connected to a respective prechamber
10, interposing a respective check valve 13.
[0092] A device 1, characterized in that at least the pressure
vessel 2, the prechamber 10 or the prechambers 10, the check
valve(s) 11, 13, the bypass line 48 or bypass lines 48, the vacuum
generating device 37 and/or the pump as a combined assembly are
situated in particular in a shared or cubic housing 112, out of
which the feed line 3 and return line 12 extend, that the assembly
encompasses a compressed air terminal 22 that is or can be
connected to a compressed air source that belongs to the assembly
or is separate from the assembly, that the prechamber 10 is
connected to the compressed air terminal 22 by at least one valve
26, that the pressure vessel 2 is connected to the compressed air
terminal 22 by at least one valve 23, and that the vacuum
generating device 37 and/or pump is connected to the compressed air
terminal 22.
[0093] A device 1, characterized in that the device 1 is connected
to a blasting cabin 14 or encompasses a blasting cabin 14, wherein
the respective blasting cabin 14 exhibits an interior 15 into which
the feed line 3 extends, and wherein the return line 12 is
connected to a collection receptacle 17 of the blasting cabin 14
for flowable media, e.g., for a flowable suspension, wherein it is
provided in particular that the drain 17 always be in a state of
pressure equalization with the environment.
[0094] A method characterized by the following procedural step:--
Aspirating suspension 72 through the end 20 of the return line 12
connected to the collection receptacle 17 of the blasting cabin 14
for the suspension, in particular by generating a vacuum in the
prechamber 10 and/or by turning on a pump arranged between the
collection receptacle 17 and prechamber 10, and opening a vent
valve 32 connected to the prechamber 10.
[0095] A method, characterized in that the method, in particular
subsequently, encompasses at least the following: [0096] Ending the
aspiration of suspension 72 through the end 20 of the return line
12 connected to the collection receptacle 17 of the blasting cabin
14, [0097] Supplying compressed air into the prechamber 10 at least
partially filled with suspension 72, and opening a vent valve
connected to the pressure vessel 2, for example which is a throttle
valve 31 or a pressure relief valve.
[0098] A method, characterized in that the method, in particular
subsequently, encompasses at least the following: [0099] Aspirating
suspension 72 through the end 20 of the return line 12 connected to
the collection receptacle 17 of the blasting cabin 14, in
particular by generating a vacuum in the prechamber 10 and/or
turning on a pump arranged between the collection receptacle 17 and
prechamber 10, and opening a vent valve 32 connected to the
prechamber 10, [0100] As this takes place, supplying compressed air
to generate overpressure in the pressure vessel 10 at least
partially filled with suspension, and [0101] Given an overpressure
in the pressure vessel 2, at least intermittently opening the valve
7 allocated to the feed line 3 so as to blast suspension 72 onto
one or several workpieces 19.
[0102] A method, characterized in that the method, in particular
subsequently, encompasses at least the following: [0103] Turning
off the compressed air supply in the pressure vessel 2, [0104]
Generating overpressure in the prechamber 10 by supplying
compressed air into the prechamber 10, [0105] Given an overpressure
in the prechamber 10, at least intermittently opening the valve 7
allocated to the feed line 3, and blasting suspension 72 onto one
or several workpieces 19, and in particular at least intermittently
opening a vent valve connected to the pressure vessel 2.
[0106] A method, characterized in that the method, in particular
subsequently, encompasses at least the following: [0107] Generating
overpressure in the pressure vessel 2 by supplying compressed air
into the pressure vessel 2 and opening the valve 49 allocated to
the feed line 48, so that at least the liquid phase of the
suspension 72 or the suspension 72 is transported from the pressure
vessel 2 into the prechamber 10, [0108] Once a specific level has
been reached in the prechamber 10, ending, in particular
automatically ending, the supply of compressed air into the
pressure vessel 2 and generating overpressure in the prechamber 10
by supplying compressed air, [0109] And in the process at least
intermittently opening a vent valve connected to the pressure
vessel 2 and/or opening the valve 7 allocated to the feed line 3
for blasting suspension 72 out of the blasting device 4.
[0110] A method, characterized in that suspension 72 is blasted
onto one or several workpieces 19, wherein the weight ratio between
the overall solid phase contained in the suspension 72 and the
overall liquid phase contained therein is greater than 0.5, in
particular greater than 0.9, and in particular has the value 1.
[0111] All disclosed features are essential to the invention
(whether taken separately or in combination with each other). The
disclosure content of the accompanying/attached priority documents
(copy of prior application) is hereby included in the disclosure of
the application in its entirety, to include for the purpose of also
incorporating features in these documents into the claims of the
present application. The features in the subclaims characterize
independent inventive further developments of prior art, in
particular so as to generate partial applications based upon these
claims.
TABLE-US-00001 Reference List: 1 Device 2 Pressure vessel 3 Feed
line 4 Blasting device 4` Nozzle holder 5 Riser pipe 6 Hose 7 Valve
8 Cover 9 Mouth 10 Prechamber 11 Check valve 11` Valve 12 Return
line 13 Check valve 13` Valve 14 Blasting cabin 15 Interior 16
Funnel floor 17 Collection receptacle 18 Workpiece receptacle 19
Workpieces 20 End 21 Line 22 Compressed air terminal 23 Valve 24
Regulator unit 25 Line 26 Valve 27 Line 28 Crossing 29 Line
junction 30 Line junction 31 Throttle valve 32 Vent valve 33 Valve
34 Line 35 Line 36 Regulator unit 37 Vacuum generating device 38
Line 39 Valve 40 Line 41 Valve 42 Regulator unit 43 Pressure supply
line 44 Line 45 Valve 46 Line 47 Valve 48 Bypass line 49 Valve 50
End 51 Ascending sifter 52 End 53 Line 54 Valve 55 Level probe 56
Level probe 57 Level probe 58 Sensor 59 Terminal 60 Pressure vessel
terminal 61 Floor 62 Terminal 63 Riser pipe 64 End 65 Passage
direction 66 Sealing element 67 Valve sleeve 68 Valve housing 69
Longitudinal section 70 Seal seat 71 Sealing edge 72 Suspension 73
Circle 74 Surface 75 Surface 76 Through opening 77 Sleeve 78
Surface 79 Longitudinal central axis 80 Fastening plate 81 Borehole
82 Nut 83 Passage opening 84 Guiding lamella 85 Guiding lamella 86
Projection 87 Edge 88 Upper side 89 Tongue 90 Screw 91 Flow-through
opening 92 Annular surface 93 Terminal 94 Prechamber terminal 95
Floor 96 Longitudinal central axis 97 Terminal 98 Passage direction
99 Cyclone separator 100 Line 101 Line 102 Terminal 103 Terminal
104 Riser pipe 105 Screwed connection 106 Hand valve 107 Nozzle 108
Hand valve 109 Pipe segment 110 Hand valve 111 Riser pipe 112
Housing 113 Wheel 114 Line .alpha. Angle .beta. Angle
* * * * *