U.S. patent number 3,859,757 [Application Number 05/328,737] was granted by the patent office on 1975-01-14 for grinding machine with belts.
Invention is credited to Karl Heesemann.
United States Patent |
3,859,757 |
Heesemann |
January 14, 1975 |
GRINDING MACHINE WITH BELTS
Abstract
A belt grinding machine, including a workpiece conveyor
mechanism, an endless grinding belt circulating above the conveyor
transversely or longitudinally of the direction of movement of the
workpiece, a resilient pressure member, associated with the said
grinding belt to move and hold the grinding belt against the
surface of a workpiece to be ground, a plurality of double acting
pressure medium-operated cylinders and pistons arranged at
intervals in the direction of the grinding movement of the belt,
wherein each pressure medium operated cylinder is secured by its
piston rod directly to the pressure member and is provided with a
duct feeding a pressure medium moving the piston to a raised
position of the grinding belt, and a duct feeding a medium for
moving the piston to a working position of the grinding belt, and a
control valve feeding the medium for the grinding pressure to the
cylinder against the lifting pressure, or evacuating the medium
from the cylinder, inserted in the duct supply medium effecting the
raised position of the grinding belt, said valve being connected to
a senser actuating a switching and control device in dependence on
the presence of a workpiece, and a timing relay operated by the
said switching and control device to operate the control valve.
Inventors: |
Heesemann; Karl (4970 Bad
Oeynhausen-Rehme, DT) |
Family
ID: |
5844444 |
Appl.
No.: |
05/328,737 |
Filed: |
February 1, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
451/300;
451/303 |
Current CPC
Class: |
B24B
21/06 (20130101) |
Current International
Class: |
B24B
21/04 (20060101); B24B 21/06 (20060101); B24b
021/08 () |
Field of
Search: |
;51/135R,137,138,139,141,148 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Al Lawrence
Assistant Examiner: Godici; Nicholas P.
Attorney, Agent or Firm: Learman & McCulloch
Claims
What is claimed is:
1. A belt grinding machine comprising a grinding belt, a flexible
pressure member for pressing an operative portion of said belt from
a normally maintained inactive position downwardly against a
workpiece conveyed in a first direction beneath said operative
portion of said belt, said pressure member extending transversely
of said first direction entirely across the width of the surface of
the workpiece to be ground, a plurality of double acting, fluid
pressure motors each having a first and a second internal chamber
divided from each other by a piston having a rod projecting from
the first chamber end of sad motor, the rods of said motors being
connected to said pressure member at spaced locations transversely
of said first direction and operable upon actuation of the
associated motor to raise or lower the section of said pressure
member connected thereto, a first pressure source commonly
connected to all of said first chambers to urge said pistons and
the connected pressure member toward a position of maximum
elevation wherein said grinding belt is in said inactive position,
a second pressure source maintained at a pressure higher than that
of said first source, valve means on each motor operable to
selectively connect the second chamber of the motor to said second
source or to vent, and delayed action control means associated with
each motor engageable with a workpiece surface at a location
upstream of the direction of movement of the workpiece from each
motor for actuating said valve means to position the grinding belt
beneath the associated motor at a position corresponding to the
position of the control means when the engaged portion of the
workpiece subsequently arrives in operative relationship with the
grinding belt.
2. A machine as defined in claim 1 wherein each of said pressure
sources comprises an elongate tank extending transversely of said
motors and fixedly secured to each of said motors.
3. A machine as defined in claim 2 wherein each of said motors has
a first passage communicating with said first chamber and a second
passage communicating with its valve means, first and second bolt
means fixedly securing said first and second tanks respectively to
said motors, said bolt means being respectively received in said
first and second passages and placing said passages respectively in
fluid communication with said first and second tanks.
4. A machine as defined in claim 3 wherein each of said bolt means
comprises a shank having a threaded end threadably received in the
motor passage, means defining an axial bore in said shank extending
from the threaded end partially the length of the bolt, and a cross
bore intersecting the axial bore establishing communication between
the axial bore and the interior of the tank.
5. A machine as defined in claim 4 wherein said first passage opens
into said first chamber at the end from which said rod projects and
said second passage communicates with said valve means, each motor
having a third passage extending from its valve means into said
second chamber at the end of said second chamber remote from said
rod.
6. A machine as defined in claim 5 further comprising stop means in
each motor establishing opposite end limits of movement of its
piston.
Description
PRIOR APPLICATION
In Germany on May 9, 1972 and numbered P 22 22 616.0.
The present invention concerns a grinding machine with means for
conveying workpieces therethrough. The machine comprises a conveyor
mechanism including belts, chains or the like moving the workpieces
to be ground, an endless grinding belt circulating transversely or
longitudinally with respect to the direction of movement of the
workpieces and located above the conveyor mechanism, and a
resilient pressure member associated with this grinding belt to
urge it against the surface of the workpieces to be ground. The
said member includes a plurality of double acting cylinders
operated by a pressure medium and arranged at adjacent spaced
intervals along the direction of movement of the grinding belt.
Such belt grinding machines which are known in various forms more
particularly for grindng flat workpieces having regular or
irregular shapes, are usually provided, with a complicated and
expensive mechanical control device for moving the grinding belt
towards the workpieces to be ground and away from the workpieces to
an inoperative position. In spite of this complication, these
machines do not give perfect grinding results, particularly in the
case of somewhat uneven workpiece surfaces.
It is an object of the present invention to improve a belt grinding
machine of the type described and to provide it with a control
means for moving a pressure member which is simply and economically
designed and which operates reliably independently of the movement
and shape of the workpiece, for a pressure member moving the
workpiece into the grinding position and inoperative position
respectively.
In a further object of the present invention, the belt grinding
machine is to be constructed with a simply designed and reliably
operating pulse transmitter for parts which move the grinding
belt.
Furthermore, the grinding belt is to be moved by simple, reliable
and smoothly operating means positively controlled in its type of
movement by the configuration of the workpiece.
A further object resides in the simple, economical and durable
construction of a grinding belt support enabling the operative
surface of the grinding belt to be adapted to the surface of the
workpiece to be ground.
In addition, individual parts or all of the grinding surface of the
belt are to be reliably moved to the grinding position in
accordance with the surface of the workpiece.
A further object is seen in the provision of grinding belt pressure
elements rendering possible grinding of both plane and uneven
workpiece surfaces.
According to the present invention there is provided a belt
grinding machine, including a workpiece conveyor mechanism, an
endless grinding belt circulating above said conveyor mechanism in
a direction selected from transversely and longitudinally of the
direction of movement of the workpiece, a resilient pressure member
associated with the said grinding belt, moving and holding the
grinding belt against the surface of the workpiece to be ground, a
plurality of double-acting pressure medium-operated cylinders and
pistons arranged at spaced intervals in the direction of the
grinding movement of the belt, each said cylinder, secured by its
piston rod directly to said pressure member, is provided with a
duct feeding a pressure medium to move the piston to a raised
position of the grinding belt and a duct feeding a medium to move
the piston to a working position of the grinding belt, a control
valve which feeds the medium for the grinding pressure to said
cylinder against the lifting pressure, or evacuates it from said
cylinder is interposed in said duct effecting the raised position
of the grinding belt and is connected by means of an electrical
switching and control device to a time relay adjustable in
dependence on the presence of a workpiece to a scanning member
actuating said switching and control device.
According to the present invention there is also provided a belt
grinding machine wherein the two actuated piston surfaces of the
piston vertically reciprocated at right angles to the plane of
movement of the workpiece, of each said cylinder are connected by
way of said duct each to a pressure medium chamber extending over
all adjacent said cylinders, preferably a closed pipe sealed at the
ends, and, from the lower pressure medium pipe of the two
superimposed said pipes, a medium is fed continuously loading the
lower actuating surface of said piston and holding or bringing it
in a lifted position and from the upper pipe a medium is fed,
greater in pressure, loading the upper piston surface and bringing
said piston into a working position dependent on the movement of
the workpiece, whilst a valve, preferably a magnetic valve, is
inserted in said pressure medium duct for the pressure movement,
said valve being controllable dependently on the workpiece, wherein
the said control valve associated with each said cylinder is
connected by way of an adjustable switching and control device,
preferably a time-relay, with a contact switch which holds on a
contact lever, a sensing member formed by a roller or the like and
actuated by the moving workpiece, wherein supporting brackets are
secured to extension arms of the machine chassis, which brackets
support on their rear side, in the direction of movement of the
workpiece, said superimposed pipes with the said cylinders secured
thereto, and the said control valve disposed thereon, and carry, on
the front side, in the direction of movement of the workpiece, said
contact switches on a vertically adjustable holding rail, wherein
the piston rod of each said cylinder is directly secured to a
cross-bar of a resilient pressure member preferably formed by an
air cushion pressure beam.
A belt grinding machine of the present invention is fitted with
control means for the respective operating and resting positions of
the grinding belt, which control means presses the grinding belt
against a workpiece surface to be ground and lifts it from the
workpiece when the grinding process is finished.
The pressure member holding the grinding belt against the workpiece
is moved by means of hydraulic cylinders under control of means for
sensing the pressure of the workpiece. Electrical switching and
control devices are actuated so that the resilient pressure member
only adapts itself to the surface of the workpiece, its capacity to
do so being improved by providing separate movement of each
individual cylinder. The pressure member is thus moved flexibly
against the workpiece by the individual cylinders, with the result
that any irregularities in the surface of the workpiece are
compensated.
The same pressure is exerted on each piston of the cylinders, and
since each piston can effect a certain stroke, compensation for
tolerances in the workpiece surface is possible within this range;
one piston may extend further than another in the direction of the
workpiece surface and thus individual portions of the grinding belt
are brought by the pressure member into contact with the workpiece
surface to be ground.
Each hydraulic cylinder is controlled by its own sensing member
which senses the edge of the workpiece and then initiates the
pressure movement of the driving belt with a delayed action. In
order that the edges of the workpieces can be perfectly ground and
grinding errors avoided, adjacent cylinders can be moved
independently of each other by one or more sensing members and one
or more coordinated electrical switching and control devices.
The control means is economically designed by the avoidance of
complicated mechanical means and the provision of time relays as
switching and control devices, and is greatly improved in its
operation compared with conventional control means.
An embodiment of the present invention is illustrated in the
accompanying drawings, in which:
FIG. 1 is a perspective view of a belt grinding machine of the
present invention;
FIG. 2 is a side view in partial section of the pressure
member;
FIG. 3 is a plan view of the pressure member arranged above the
conveyor; and
FIG. 4 is a front view of the pressure member showing the pressure
operated cylinders.
A belt grinding machine according to the present invention for
grinding regularly or irregularly shaped plate-like workpieces 10,
which may have an even or somewhat uneven surface, has a machine
frame 11, a motor-driven conveyor 12, shown as including endless
belts, the conveyor moving the workpieces 10 to be ground, in a
continuous process. Above this conveyor 12 is mounted an endless
grinding belt 13 which circulates transversely to the direction of
movement of the workpieces and is motor-driven independently of the
conveyor 12. The belt is held against the workpiece 10 in the
grinding position by a resilient pressure member 14, extending
substantially over the lower length of the grinding belt 13 between
its two guide pulleys 15, or between guide pulleys 49 of a
laminated pressure belt 48.
This pressure member 14 has a plurality of fluid pressure operated
cylinders 16 which are arranged adjacent each other at uniformly
spaced intervals along the direction of movement of the grinding
belt and effect a movement of the pressure member 14 into a
grinding position (the grinding belt 13 is pressed against the
workpiece surface to be ground) or into a raised position (no
grinding contact between grinding belt 13 and workpiece
surface).
Each cylinder 16 is attached to the pressure member 14 by its
piston rod 17 which is displaceable at right angles to the plane of
movement of the workpiece; this piston rod 17 is actuated by a
double-acting piston 18 in cylinder 16 which may be displaced
backward or forward by a pressurised fluid, preferably air, though
it may also be oil or other liquid. This moves the pressure member
14 into a resting or operative position.
Each cylinder 16 is provided with ducts feeding the pressure medium
to produce a raised or working position of the grinding belt. In
the duct producing the working position of the grinding belt is
inserted a control valve 19 which supplies the medium for applying
grinding pressure to the pressure operated cylinder 16 or evacuates
it from the cylinder. The valve is actuated by a relay 20 and a
senser 21.
The cylinder space of each pressure operated cylinder 16 is divided
into two chambers 22, 23 by double acting piston 18. It is
provided, near the chamber 22 adjacent to the pressure member 14,
with a duct 25 connecting this chamber 22 to a pressure medium
chamber 24, and near its chamber 23 with a duct 26 which connects
the chamber 23 to a pressure medium chamber 27 and the control
valve 19.
The two pressure medium chambers 24, 27 are separated from each
other and extend across all the pressure operated cylinders. These
two pressure medium chambers are of rectangular cross section, the
depth of which corresponds to the length of each cylinder.
Two spaced apart supporting brackets 28 are disposed on extension
arms 11a on the machine chassis 11 above the grinding belt 13. They
carry on their rear sides the two superimposed chambers 24, 27 and
on their front sides, a support member 29 on which the sensers are
mounted.
The housing 30 of each pressure medium cylinder 16 is provided at
its lower end with a projecting piston rod 17, displaceable in a
vertical plane and, at its upper end, carries the control valve 19.
Near each pressure medium cylinder 16, each chamber 24, 27 is
traversed by a connecting means, preferably a bolt 31, 32 which
acts to keep the cylinders 16 in contact with the chambers 24, 27
and thus with the holding brackets 28, and also effects a flow path
between the chambers 24, 27 and respective ducts 25, 26. For this
purpose each bolt 31, 32 provided with an axial blind bore 33, 34
extending in the longitudinal direction of the bolt, the bores
being connected to the chambers 24, 27 by several transverse bores
35, 36 formed in the portion of the bolts extending within the
chambers 24, 27.
Each of the two bolts 31, 32 for each pressure medium cylinder 16
screws into the housing 30 of the cylinders and the ducts 33, 34
then communicate with the ducts 25, 26 of the housing 30. The duct
25 is an angle member which is connected with the bolt duct 33 and
terminates in the bottom of the chamber 22.
The duct 26 is composed of two parts, angled part connected to the
bolt duct 34 and communicating with the control valve 19 and a part
extending from the control valve 19 and terminating in the bottom
of the housing opposed to the angled duct 25.
The scanning member 21 is a scanning roller journalled to rotate on
a switching lever 37a of a contact switch 37. The contact switches
37 are mounted with the interposition of spacers 38, on a
vertically adjustable supporting rail 39 which is secured by means
of the spacers 38 to the support member 29. Each contact switch 37
is connected by an electrical lead 40 to a switching and control
device 20 and each switching and control device 20 is connected by
an electrical lead 41 to the control valve 19 whch is
electro-magnetically operated.
A control valve 19 is associated with each pressure medium cylinder
16, senser 21 is provided with a contact switch 37 and a time delay
relay 20, and each pressure medium cylinder and piston is actuated
independently of the other cylinders.
Alternatively a scanning member 21 with contact switch 37 and a
time relay 20 is provided in common to several pressure medium
cylinders 16 so that the control valves of several cylinders are
controlled by one scanning member 21.
The two chambers 24, 27, as supply means for all the cylinders 16,
are each connected by a pipe with a pressure reducing valve, to a
pressure medium supply.
In the chamber 24 there is always a pressure medium which transmits
its force through the bores 35, the duct 33 and the duct 25 in the
housing 30 to the chamber 22 so that there is always a pressure
medium in the chamber 22 acting on the underside of each piston 18.
If there is no workpiece 10 passing through the machine, the
contact roller 21 is not actuated and the control valve 19 is not
operated, so that the pressure medium (compressed air) in the
chamber 22 displaces the piston 18 into a resting position, the
pressure member 14 being in the upper resting position. The piston
18 is held against a stop 30a of housing 30 in this resting
position by the compressed air. When a workpiece 10 passes into the
machine to be ground, it presses the scanning roller 21, adjusted
to a point somewhat lower than the upper edge of the workpiece, in
the direction of the pressure member 14 so that the contact switch
37 is operated by the switch lever 37a. After a time which is
previously set on the time delay relay 20, and which corresponds to
time taken by the front edge of the workpiece to move to
approximately the centre of the pressure member 14, the control
valve 19 is operated so that the pressure medium reaching the
control valve 19 from the chamber 27 through the bores 36, the duct
34 and the angle duct 26, can now flow through the control valve
and enter the upper chamber 23 through the straight duct 26. The
pressure of this medium is greater than the pressure of the medium
in the chamber 22 and this forces the piston 18 into a working
position in which the pressure member 14 holds the grinding belt 13
against the surface of the workpiece to be ground.
The lowest position of the piston 18 is determined by a stop 30b on
the housing 30.
When the rear edge of the moving workpiece 10 releases the scanning
roller 21, this roller returns to its original position and opens
the contact switch 37; after a time previously set on the timing
relay which corresponds to the time taken by the rear edge of the
workpiece to move from the roller 21 to approximately the centre of
the pressure member 14, the magnetic valve 19 is released and the
chamber 25 above the piston 18 is evacuated by the valve 19.
The pressure of the medium in the chamber 22 then returns the
piston 18 and the pressure member 14 to the upper resting
position.
The resilient pressure member 14 is formed as a beam which has a
cross bar 42 which is secured to the piston rods 17 and on which
two spaced apart steel plates 24 are mounted by bolts 43. An air
cushion 45 is located between the plates. A felt mat 46 is secured
below the lower steel plate 44 by cementing the lower side (the
side adjacent the grinding belt 13,) is covered by a sliding mat 47
secured at one end to the pressure member 14 and held at the other
end with adjustable tension by a tensioning device.
This pressure member 14 formed in such manner can act by its
sliding mat 47 on the grinding belt 13 or bear against the grinding
belt 13 with the interposition of an endless circulating laminated
pressure belt 48.
The air pressure in the air cushion 45 of the pressure member 14
corresponds to the pressure of the grinding belt 13 so that any
tolerances (unevenesses) in the surface of the workpiece can be
compensated by the elastic construction of the pressure member 14
within the air cushion 45.
Due to the large number of pressure operated cylinders 16 and
scanning members 21 associated therewith, individual portions of
various widths and shapes of the workpieces 10 passing through are
scanned and then the pressure operated cylinders 16 are actuated.
Each piston 18 has a certain stroke so that unevenesses in the
workpiece surface are compensated by strokes of the pistons 18 of
different length and the grinding belt 13 rests, due to the pistons
18, on the complete surface of the workpiece to grind it.
FIG. 4 of the drawings shows the grinding of a hollow round
workpiece surface; the pistons 18, due to the contact pressure are
displaced downwardly to a varying extent, the pistons 18 being
lowered in their lowest position to the portion of the surface
which is deepest and the pistons lowered to a portion of the
surface which is not so deep being lowered to a lesser extent.
Individual portions of the pressure member 14 are moved more or
less downwardly by the pressure operated cylinders 16 so that the
grinding belt 13 is always completely in contact with the surface
of the workpiece to be ground, thus any uneven surfaces are ground
and tolerances in the surface of the workpiece compensated.
The pressure of all the pressure operated cylinders 16 is the same
over the pressure member 14, only individual portions of the
pressure member are pressed further down against the workpiece 10
according to the surface of said workpiece. By a fine adjustment of
grinding pressure and counter-pressure it is possible for the
piston 18 to float between the upper and lower end position (30a,
30b) so that comparatively large workpiece tolerances can be
compensated in this manner, this compensation of tolerances being
also assumed by the elastic pressure member 14.
It is preferable to use relays 20 having five poles and
accommodated in the switch cabinet 50 so that not only the contact
switches directly operated by the workpiece 10 and hence the
associated cylinders 16 are operated, but also a plurality of
adjacently disposed cylinders 16; this ensures that the edges of
the workpieces are also exactly ground.
It is also within the scope of the present invention to provide
more or less than five pole relays if the switching and control
device 20 requires this.
In a special switching arrangement two or more groups of pressure
operated cylinders may be combined so that they are controlled by
respective scanning members. This enables a double or multi-track
feeding of the machine to be possible in the grinding of regularly
shaped workpieces.
* * * * *