U.S. patent number 3,929,320 [Application Number 05/467,143] was granted by the patent office on 1975-12-30 for foundry mixing machine.
This patent grant is currently assigned to Escher Wyss Limited. Invention is credited to Walter Haller.
United States Patent |
3,929,320 |
Haller |
December 30, 1975 |
Foundry mixing machine
Abstract
A foundry mixing machine for preparing a mixture of sand and an
admixture is disclosed; the machine has an inlet for the sand,
followed by an annular slot for the sand, then an annular admixing
space and an outlet for the mixture; a feeding device for the
admixture is disposed on the admixing space and leads into the
admixing space; between the admixing space and the outlet for the
mixture there are disposed two relative to one another rotatable
bodies of revolution between which an annular intermediate space is
left open for the mixture; the bodies have projections towards the
intermediate space; the form of the projections is shown;
furthermore improvements on the feeding device for the admixture
are shown.
Inventors: |
Haller; Walter (Schlieren,
CH) |
Assignee: |
Escher Wyss Limited (Zurich,
CH)
|
Family
ID: |
27509224 |
Appl.
No.: |
05/467,143 |
Filed: |
May 6, 1974 |
Foreign Application Priority Data
|
|
|
|
|
May 7, 1973 [CH] |
|
|
6411/73 |
Dec 21, 1973 [CH] |
|
|
18002/73 |
Dec 21, 1973 [CH] |
|
|
18003/73 |
Dec 21, 1973 [CH] |
|
|
18004/73 |
Apr 9, 1974 [CH] |
|
|
4984/74 |
|
Current U.S.
Class: |
366/101; 366/274;
366/317; 366/601 |
Current CPC
Class: |
B22C
5/02 (20130101); Y10S 366/601 (20130101) |
Current International
Class: |
B22C
5/02 (20060101); B22C 5/00 (20060101); B28C
005/16 () |
Field of
Search: |
;259/7,8,178A,164,165,168,161,23,24,43,44,66,67 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Jenkins; Robert W.
Attorney, Agent or Firm: Ostmann; Robert A.
Claims
I claim:
1. A foundry mixing machine for preparing a mixture of sand and an
additive having at least two liquid components, the machine
comprising
a. wall means defining a sand inlet chamber, a preliminary mixing
chamber located below the inlet chamber, and an annular slot
positioned vertically between said chambers and serving to allow
sand to descend by gravity, and in the form of an annular curtain,
from the inlet chamber to the preliminary mixing chamber,
b. said slot being defined by cooperating walls which are movable
relatively to each other to vary the width of the slot;
c. a feeding and spraying device in the preliminary mixing chamber
and including a separate duct for each of said liquid components
and an additional duct for compressed air,
d. the ducts leading into the preliminary mixing chamber and being
so arranged relatively to each other and to said slot that
compressed air admixes the liquid components and propels the
admixture into said annular curtain of sand which descends through
said slot;
e. an annular final mixing chamber having an inlet at its inner
margin which communicates with the preliminary mixing chamber at a
region radially outward of said descending annular curtain of sand,
and an outlet at its outer margin,
f. the final mixing chamber being defined by a gap bounded by two
axially spaced, relatively rotatable bodies of revolution, each of
which carries projections which extend toward the gap;
g. a drive motor located below, and connected to cause relative
rotation of, said bodies of revolution; and
h. additional wall means which surrounds the bodies of revolution
and defines a duct which leads mixture existing from the outlet of
the final mixing chamber downward to an outlet located below said
bodies of revolution.
2. A mixing machine as defined in claim 1 in which each body of
revolution has a base wall from which the projections extend; and
the projections of the two bodies overlap one another in the
direction normal to said base walls.
3. A mixing machine as defined in claim 2 in which said projections
are solid annular walls.
4. A mixing machine as defined in claim 3 in which each projection
has, on its upstream side, a surface inclined in the direction of
flow of mixture through the final mixing chamber.
5. A mixing machine as defined in claim 3 including blades carried
by each projection of one of the bodies of revolution which extend
in the direction of flow of mixture nearly to the adjacent
projection on the other body of revolution.
6. A mixing machine as defined in claim 1 including magnetic means
associated with at least one of the bodies of revolution and
serving to hold the body to a supporting element.
7. A mixing machine as defined in claim 6 in which said one body of
revolution and said supporting element are made of non-magnetic and
magnetic materials, respectively; and including permanent magnet
means built into said one body of revolution.
8. A mixing machine as defined in claim 1 in which the projections
of each body of revolution are spaced axially from the other body a
distance just sufficient for the passage therebetween of the
mixture.
9. A mixing machine as defined in claim 1 in which the preliminary
and final mixing chambers lie in a common plane.
10. A mixing machine as defined in claim 1 in which said ducts have
outlets so arranged that the compressed air issuing from its duct
impinges upon the liquid components issuing from the other
ducts.
11. A mixing machine as defined in claim 10 in which the outlet of
the compressed air duct is located radially outward of the other
outlets.
12. A mixing device as defined in claim 10 in which the outlet of
the compressed air duct includes a nozzle for the compressed
air.
13. A mixing machine as defined in claim 10 in which the feeding
and spraying device includes wall means which defines a feed
chamber having a cylindrical side and an open lower end which leads
into the preliminary mixing chamber; and the outlets of said ducts
open into the feed chamber.
14. A mixing machine as defined in claim 13 in which the outlet of
the compressed air duct opens tangentially into said feed
chamber.
15. A mixing machine as defined in claim 13 in which the outlets of
the ducts for the liquid components are arranged to direct said
components against the cylindrical side of the feed chamber.
16. A mixing machine as defined in claim 1 in which said feeding
and spraying device is located at the center of the preliminary
mixing chamber.
17. A mixing machine as defined in claim 1 including an enclosing
casing having two separable sections which can be parted easily to
afford free access to at least one of said bodies of
revolution.
18. A mixing machine as defined in claim 17 in which said separable
sections join in a plane along which lies the final mixing
chamber.
19. A mixing machine as defined in claim 1 including an enclosing
casing having three separable sections, there being an upper
section which contains said sand inlet chamber, annular slot and
feeding and spraying device, an intermediate section which is
formed on the inside as one of said bodies of revolution, and a
lower section defined by said additional wall means; and clamping
means interconnecting the upper and lower casing sections and
holding those sections against the intermediate section.
20. A mixing machine as defined in claim 1 including a supply pipe
connected to each of said liquid component ducts and provided with
a pilot valve; a servomotor connected to effect relative movement
between said slot-defining walls and thereby open and close said
slot; and switching means connected to control the drive motor, the
pilot valves and the servomoor and having at least a first state in
which it switches off the drive motor, causes the pilot valves to
block flow of liquid to said ducts and causes the servomotor to
effect closure of said slot, a second state in which it energizes
the drive motor and maintains the pilot valves and the servomotor
in their initial positions, and a third state in which it energizes
the drive motor, causes the servomotor to open the slot and causes
the pilot valves to interconnect the ducts and the supply
pipes.
21. A mixing machine as defined in claim 20 in which each supply
pipe is connected to receive a liquid component from a variable
delivery dosing pump; and each supply pipe is provided with an
overflow device which carries away the liquid delivered thereto by
the associated pump when the pilot valve blocks flow from the pipe
to the associated duct.
22. A mixing machine as defined in claim 2 in which each dosing
pump is driven by an electric motor connected with a potentiometer
which controls its speed, whereby the delivery rates of the pumps
are controlled by the settings of the potentiometers.
23. A mixing machine as defined in claim 22 in which each electric
motor is provided with a group of parallel connected
potentiometers, and with a selector switch which serves selectively
to connect the motor in a circuit with any one of the
potentiometers of the associated group.
24. A mixing machine as defined in claim 23 in which the selector
switches are incorporated in the switching means and are so
arranged that each pump motor is shut off in said first state and
runs under the control of different potentiometers in said second
and third states.
25. A mixing machine as defined in claim 20 including a pipe
connected to supply compressed air to said compressed air duct and
provided with a pilot valve; and wherein the pilot valve of the
compressed air pipe is connected to be opened and closed by the
switching means in unison with the other pilot valves.
26. A mixing machine as defined in claim 1 in which all of said
elements are incorporated in an assembly which is mounted for
pivotal movement on an arm; and said arm is mounted in an upright
standard for rotational movement about its longitudinal axis.
27. A mixing machine as defined in claim 26 including a pair of
servomotors, one being connected to pivot the assembly relatively
to the arm, and the other being connected to rotate the arm in the
upright standard; and common control means, including a control
stick, for operating the servomotors.
Description
BACKGROUND OF THE INVENTION
The invention relates to a foundry mixing machine for preparing a
mixture of sand and an admixture, said machine having an inlet for
the sand, followed by an annular slot for the sand, followed again
by an annular admixing space and furthermore, disposed on said
annular admixing space, a feeding device for the admixture, leading
into the admixing space, and an outlet for the mixture.
A moulding sand mixture, which is prepared in a mixing machine of
this kind for example from a sand and a liquid, organic admixture
having at least two components, viz a binder and a hardener, is
used in foundries for making precision moulds.
The foundry mixing machines which were previously known are
relatively big, stationary units from which the mixture has to be
conveyed specially to the place where it will be used in the
moulding bay of the foundry. Another known foundry mixing machine
(U.S. Pat. No. 3,773,299) has the disadvantage that the feeding
device has a centrifuge and because of the high speed of the
centrifuge there is a risk of spontaneous combustion of the liquid,
organic admixture and possibly its explosion. Furthermore, the
known mixing units require several operators. The previous mixing
machines also become clogged up in the course of time owing to
adhesion of the sticky moulding sand mixture.
SUMMARY OF THE INVENTION
The problem underlying the invention is to obviate the
above-described disadvantages and to provide a foundry mixing
machine which is smaller than the conventional ones, free from
trouble and can be used without risk with only a few operators in
the moulding bay of a foundry.
This problem is solved according to the invention, on a foundry
mixing machine of the type mentioned initially, through the fact
that there are disposed between the admixing space and the outlet
two bodies of revolution which are rotatable relative to one
another, between which a ring-shaped intermediate space is left
open for the mixture, and that in this intermediate space on the
walls of the bodies of revolution there is a projection towards the
intermediate space provided in each case, the projection of one
body of revolution and that of the other overlapping one another in
the direction perpendicular to the walls of the bodies of
revolution.
It is advantageous to the construction of the intermediate space if
the projections are solid annular walls and, furthermore, if the
projections have, on the mixture inflow side, a surface ascending
from the wall of the body of rotation in the direction of
throughflow of the mixture.
A complete and safe thorough mixing of the admixture is obtained by
the provision of a compressed air line which conducts the
compressed air into the vicinity of the opening of a pipe for the
admixture which is provided in the feeding device, preferably by
means of the fact that the feeding device opens out into the middle
of the annular admixing space and also that the compressed air line
opens outside the point at which the admixture pipe opens out.
To allow for a breakdown in operations owing to clogging of the
intermediate space lying between the bodies of revolution it is
advantageous if at least one of the two bodies of revolution which
can rotate relative to one another is held by means of magnetic
force to the element supporting it and furthermore that the foundry
mixing machine is capable of being divided up so that at least one
body of revolution is easily accessible.
The foundry mixing machine can be operated by one person only, if a
separate stock bin is provided for the sand and for the admixture
and a supply line is provided which can be put under pressure, the
supply line being fitted with a pilot valve in each case, and if a
switching device is provided for switching on the driving motor for
the body of revolution and, when the operating speed of the driving
motor and the pressure in the supply line has been reached, for
opening the pilot valves and also for closing the pilot valves and
then switching off the driving motor. Simplification of operation
is achieved, moreover, by means of an arm which is mounted so as to
swivel relative to the housing of the foundry mixing machine and
which in turn is mounted so as to be rotatable about its axis in an
upright.
BRIEF DESCRIPTION OF THE DRAWING
The subject of the invention is further described and explained
with reference to the accompanying drawings, in which:
FIG. 1 is an axial sectional view of one embodiment of the mixing
machine.
FIG. 2 is an axial sectional view of a second version of the
machine.
FIG. 3 is a partially sectional elevation view of a third version
of the machine which employs a casing having three separable
sections.
FIG. 4 is a diagrammatic representation of another embodiment of
the machine which incorporates various control features.
FIG. 5 is a partly sectioned elevation view of a further version of
the machine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In all the figures the same parts of a foundry mixing machine
according to the invention have been given the same references.
The foundry mixing machine has an inlet 1 for the sand. Following
the inlet 1 is an annular slot 2 through which the sand is
conducted into an annular admixing space 3. Disposed on the
admixing space 3 is a feeding device which has pipes 5, 6, 60 for
the admixture material. The admixture consists of a binder and a
hardener which are each led separately into the admixing space 3
through a pipe 5 and 6, respectively, forming part of the feeding
device. The pipes 5 and 6 are each provided with a valve 5.sup.1
and 6.sup.1 respectively for regulating the supply of admixture.
The two components of the admixture are added to and mixed with the
sand in the admixing space 3. The mixture of sand and admixture
leaves the moulding sand mixer through an oulet 7. In this
arrangement the longitudinal axis of the foundry mixing machine is
vertical.
Disposed between the admixing space 3 and the outlet 7, for more
thorough mixing of the mixture which is mixed together in the
admixing space 3, are two bodies of revolution 8 and 9, which can
be rotated relative to one another, between which an annular
intermediate space 10 is left. One body of revolution, with the
reference 8, is stationary while the other 9 is rotatable. The
walls 11 and 12 of the bodies of revolution 8 and 9 respectively
have projections 13 and 13' towards the intermediate space 10. The
projections 13 of one body of revolution 9 and the projections 13'
of the other body of revolution 8 overlap one another in the
direction perpendicular to the walls 11 and 12, thus producing a
zig-zag path through the intermediate space 10 for the mixture.
The intermediate space 10 lies substantially in the plane of the
annular admixing space 3.
The feeding device for the admixture, with pipes 5 and 6 for the
individual components of the admixture, is located in the middle of
the moulding sand mixer and opens out into the middle of the
annular admixing space 3. For mixing the two components together
and accelerating them a compressed air line 60 is provided which
conducts the compressed air close to the opening outlets of the
pipes 5 and 6 for the admixture components. The compressed air line
60 opens out outside the outlet openings of the pipes 5 and 6.
It might be conceivable, in another form of construction, for the
compressed air line to conduct the compressed air into the pipe for
the admixture material in the vicinity of its outlet opening. It
might also be conceivable that the introduction of the admixture
material was carried out in the radial direction from the exterior
into the admixing space 3.
The outlet opening of the compressed air line is provided with a
nozzle 62. The compressed air line 60 is connected to a source of
compressed air -- not shown -- and provided with a shut -off valve
61. This valve 61 can be operated by remote control.
Disposed on the feeding device is a ring chamber 63 which is open
into the admixing space 3 and into which the pipes 5 and 6 for the
components of the admixture and the compressed air line 60 open
out. The nozzle 62 is inserted in the cylindrical wall of the ring
chamber 63 in such a way that the compressed air flows tangentially
into the ring chamber 63. The outlet openings of the pipes 5 and 6
for the components of the admixture are directed against the
cylindrical wall of the ring chamber 63.
The air vortex produced in the ring chamber 63 thoroughly mixes the
components of the admixture and this mixture flows very
energetically into the admixing space 3 where the sand is
completely saturated with the mixture of air and admixture
material.
In this form of construction the two bodies of revolution 8 and 9
are essentially two discs lying parallel to one another. The bodies
of revolution might also be in the form of cones, for example.
The projections 13 and 13' are solid annular walls and on the side
on which the mixture flows in, i.e. pointing towards the admixing
space 3, each has a surface 14 and 14' ascending from 12 and 11,
respectively, in the direction of throughflow of the mixture.
Between the projections 13 of the body of revolution 9 and the wall
11 of the body of revolution 8 and between the projections 13' of
the body of revolution 8 and the wall 12 of the body of revolution
9, a clearance such as that marked 15 is left open in the direction
perpendicular to the wall 11 and 12 and is always just sufficient
for the passage of the mixture.
The intermixing of the mixture in the intermediate space is
effected by acceleration at the rotating body of revolution 9,
slinging along the ascending wall 14, retardation at the projection
13' of the body of revolution 8, slipping on to the body of
revolution 9 from the wall 14' and so on.
For the purpose of operating with the foundry mixing machine over a
moulding bay in a foundry, the mixing machine is provided with the
means of mobile suspension, with eyes 16 for example. This mobile
suspension makes it possible to bring the mixing machine into the
particular position which is required without any trouble so that
the moulding sand mixture can be brought to all points of a flask
directly from the mixing machine.
To provide for the possibility of th risk that the sticky mixture
might remain adhering to the projections 13' or the walls 14' of
the body of revolution 8, the rotating body of revolution 9 is
provided with blades, shown at 17. Each blade 17 is fixed at the
back of the projection 13 in the direction of through flow of the
mixture, extends nearly to the next projection 13' of the other
body of revolution 8, and is intended for scraping off any mixture
which may be adhering to this projection 13'.
The annular slot 2 is bounded inwardly in the radial direction by a
bell-shaped screen 18 of the feeding device. Inserted in the wall
which forms the external boundary of the slot 2 is a valve part 19.
The valve part 19 can be slid axially to the bell-shaped screen 18
as far as a saddle surface 21 on the screen. The sliding of the
valve part 19 is effected by means of screws 20, for example.
The body of revolution 9 can be rotated by means of an electric
motor 22. The electric motor runs at approximately 1300 r.p.m. so
that there is no risk as regards spontaneous combustion or
explosion of the admixture material.
The electric motor 22 is suspended on a carrier 23 which is
connected with the non-rotating body of revolution 8 by way of a
pin 24 and a wall 25. The wall 25 and a funnel-shaped part 28 serve
to conduct the mixture from the intermediate space 10 to the outlet
7.
The inlet 1 for the sand is provided with a flexible pipe part 26
and a slide valve 27 and is connected to a sand stock bin, which is
not shown.
As is shown in FIG. 2, should the foundry mixing machine break down
owing to clogging of the intermediate space 10 situated between two
bodies of revolution 8, 9, it can be made fit for service again
with the utmost speed and simplicity. To this end the bodies of
revolution 8 and 9 are held by magnetic force on to the elements
8.sup.1 and 9.sup.1 which carry them respectively; and the foundry
mixing machine can be opened quickly and easily thus rendering the
intermediate space 10 with the bodies of revolution 8 and 9 readily
accessible.
The bodies of revolution 8 and 9 are constructed essentially of a
non-magnetic material and the elements 8.sup.1 and 9.sup.1 which
carry the bodies of revolution 8 and 9 of magnetic material.
Rigidly built into the bodies of revolution are permanent magnets
8.sup.2 and 9.sup.2 respectively, the magnetic force of which holds
the bodies of revolution to the supporting elements. The connection
is secured from twisting by means of a pin 8.sup.3 or a flute
9.sup.3.
A housing wall 25 bounding the intermediate space 10 radially
outwards is divided axially in the plane of the intermediate space
10 into a part 25.sup.1 and a part 25.sup.2. The first part
25.sup.1 is connected to a part of the foundry mixing machine which
has the first body of revolution 8, and the second part 25.sup.2 is
connected with a second part of the foundry mixing machine having
the other body of revolution 9. These two parts of the mixing
machine are capable of being folded relative to one another by
means of a hinge 31. The folding of the two parts together and
apart round the axis of the hinge 31 of the mixing machine is
effected by means of a servo arrangement which has the reference
32.
In the event of clogging of the intermediate space 10, i.e. if the
mixture has adhered firmly to the bodies of revolution 8 and 9, the
intermediate space 10 is opened by swinging the two parts of the
foundry mixing machine open and removing the bodies of revolution 8
and 9, which are preferably constructed from a light synthetic
material, from the elements 8.sup.1 and 9.sup.1 which carry them
and cleaning them or replacing them by spare parts from stock,
after which the two parts of the mixing machine are swung back
again and the machine is ready for use again, all this being
achieved without any diffuclt dismantling operations.
As is shown in FIG. 3 a foundry mixing machine may also be
constructed so as to be divisible in three parts. That is to say a
first part, which is essentially an inlet 1 for the sand, a second
part, which is the first body of revolution 8 following the inlet
1, and a third part which is essentially an outlet 28 for the sand
and which also has the second body of revolution 9 and its driving
motor. These three parts of the mixing machine are held together by
means of a clamping arrangement 33, 34, 35. The clamping
arrangement has a first yoke 33 which is connected to a first
mixing machine part, viz the inlet 1, and a second yoke 35 which is
connected to the third part of the mixing machine, viz the outlet
28.
The connection between the two yokes 33, 35 is established by means
of bars 34. The bars 34 are connected rigidly to the second yoke 35
and guided slidingly in the first yoke 33. Each of the bars 34 is
connected to the piston of a servomotor 34.sup.1 mounted on the
first yoke 33, whereby they can be moved in their axial
direction.
In the event of the above-described operational breakdown the
second yoke 35 can be moved away by means of the servo motors
34.sup.1, as a result of which the foundry mixing machine opens
sufficiently between the inlet 1 and the first body of revolution 8
so that the first body of revolution can be removed from the outlet
28 for the sand. In this example of construction the body of
revolution 8 has no magnet. Removal of the first body of revolution
8 renders the other body of revolution 9 freely accessible so that
it can be taken away simply by overcoming the magnetic force
holding it to the supporting element. The cleaned bodies of
revolution 8 and 9 are then replaced in position, the mixing
machine is closed by returning the second yoke 35 by means of the
servomotors 34.sup.1 and the unit is then ready for service once
again.
It was found that owing to faulty operation there were breakdowns
consisting in the fact that after the driving motor had been
switched off the sand and the admixture material continued to flow
into the intermediate space 10 between the bodies of revolution 8
and 9 and remained there where, as a consequence of the reaction of
the admixture material, they developed into a hard and adhesive
mass.
As is shown in FIG. 4, the sand and the admixture material are each
led through a supply pipe from the stock bin to the admixing space
3 of the foundry mixing machine. The compressed air in the
compressed air line 60 comes from a compressed air plant which is
not shown. The stock bin for the sand is also not shown in the
drawing. In the sand supply pipe, which is continuously under
pressure from the column of sand in the inlet 1, there is disposed
on the annular slot 2 a remote-controlled pilot valve, of which one
of the servomotors is designated by 19.sup.1. The admixture
material has two components, each of which is conducted from a
separate stock bin 36 and 36.sup.1 respectively by way of a
separate supply line to the admixing space 3. For a first component
of the admixture there is a stock bin 36 from which the first
component of the admixture is supplied by way of a controllable
dosing pump 38 which has a driving motor 40 through a supply pipe 5
to the mixing space 3. A pilot valve 5.sup.1 is disposed on the
supply pipe 5. Since the dosing pump runs even when the pilot valve
5.sup.1 is blocking the supply pipe 5, the pilot valve 5.sup.1 is
in the form of a two-way valve in order to form an overflow
arrangement and its first way connects the two parts of the supply
pipe 5 connected to the valve 5.sup.1, while the second is
connected to an overflow pipe 39 leading back to the stock bin 36.
A remote-controlled servomotor associated with the pilot valve
5.sup.1 switches in the first or the second valve way. The portion
of the supply pipe 5 between the pilot valve 5.sup.1 and the
intermediate space 3 is as short as possible and is so constructed
that when the pilot valve 5.sup.1 is in the closed position the
admixture material does not flow out of it.
The pressure in the supply pipe 5 can be regulated by means of the
dosing pump 38 through the adjustment of the revolutions of its
driving motor 40, for which purpose at least one adjustable
potentiometer 41 is connected before this motor 40. In this example
of construction the regulation of the motor 40, or the dosing pump
38, is carried out by connecting up before the motor 40 three
potentiometers 41.sup.1, 41.sup.2, 41.sup.3, disposed parallel to
one another, each being adjustable to a desired value and capable
of being switched into a circuit of the driving motor 40 by means
of a selector switch built into a switching device 42. This makes
it possible to adjust in advance three desired dosing values which
can then be switched on while the foundry mixing machine is in
operation simply by operating the selector switch built into the
switching device 42, said dosing values being, for example, a value
for starting up (high dose -- position A-B), for normal operation
(medium dose -- position C) and a value before switching off (low
dose -- position D-E). For the second component of the admixture a
system is provided which is the same as that already described and
which has the stock bin marked 36.sup.1. The compressed air line 60
is provided with a pilot valve 61.
The pilot valves for the admixture components, one of which is
marked 5.sup.1, the pilot valve 19 for the sand with its
servomotors 19.sup.1, the compressed air pilot valve 61, the
driving motor 22 for the body of revolution 9 and the motors 40 of
the dosing pumps 38 are all controlled by way of a common switching
device 42.
The circuits for the individual switching positions of the
switching device are arranged as follows:
in the position marked 0
the driving motor 22, the motors 40 of the dosing pump 38 are
switched off and the pilot valves 19 and 5.sup.1 and 61 are
closed;
in position A:
driving motor 22 and motors 40, by way of potentiometer 41.sup.1,
are switched on, pilot valves 19 and 5.sup.1 and 61 are closed;
in position B:
the driving motor 22 and the motors 40 have reached their operating
speeds, the pilot valves 19, 5.sup.1 and 61 are opened;
in position C:
the driving motor 22 is running, the pilot valves 19, 5.sup.1 and
61 are open, the motors 40 are switched on by way of potentiometer
41.sup.2 ;
in position D:
driving motor 22 is running, pilot valves 19, 5.sup.1 and 61 are
open, motors 40 are switched on by way of potentiometer 41.sup.3
;
in position E:
driving motor 22 is running, motors 40 are running (by way of
potentiometer 41.sup.3), pilot valves 19, 5.sup.1 and 61 are
closed.
In the line between the switching device 42 and the pilot valves 19
and 5.sup.1 and 61 there is provided a contact breaker 37 by means
of which the pilot valves 19 and 5.sup.1 and 61 can be closed
additionally at any time.
FIG. 5 shows that the housing 1.sup.1 of the foundry mixing machine
is connected, for swivelling motion, to an arm 45 which arm 45 in
turn is mounted, for rotation about its axis, in an upright which
has the general reference 46.
The housing 1.sup.1 of the foundry mixing machine has two pins 43
situated opposite one another which are rotatably mounted in a fork
piece 44 of the arm 45. The arm 45 is mounted, for rotation abouts
its axis, in a bearing 46.sup.1 on the upright 46. To swing the
foundry mixing machine relative to the arm 45 there is a servomotor
48 which is connected to the arm 45 and to the housing 1.sup.1 of
the mixing machine. For rotating the arm 45 relative to the upright
46 there is a servomotor 49 which is connected to the arm 45 and
the upright 46. These two servomotors 48 and 49 are controlled
together by a device 50 with a control stick 50.
With the above-described features it is possible to shake the
mixture on to various places in a moulding bay and the position of
the foundry mixing machine required for this purpose can be
adjusted simply by the operation of a stick 50.sup.1 by the
operating person.
* * * * *