U.S. patent number RE30,096 [Application Number 05/851,620] was granted by the patent office on 1979-09-18 for food patty molding machine.
This patent grant is currently assigned to Formax, Inc.. Invention is credited to Louis R. Richards.
United States Patent |
RE30,096 |
Richards |
September 18, 1979 |
Food patty molding machine
Abstract
A high speed food patty molding machine, for manufacturing
hamburger patties or other molded food products, comprising two
large piston pumps operating in overlapping alternation to feed
moldable food material continuously to a manifold that in turn
feeds a cyclic molding mechanism. The molding mechanism need not
operate synchronously with the pumps; the volumetric capacity of
each pump is several times larger than the volume of meat or other
moldable feed material required to fulfill a molding cycle. The
pressure of the food feed is adjustable for different product
requirements. The molding mechanism includes an elevator system for
raising the complete mold assembly to a changeover position.
Inventors: |
Richards; Louis R. (Mokena,
IL) |
Assignee: |
Formax, Inc. (Mokena,
IL)
|
Family
ID: |
26914762 |
Appl.
No.: |
05/851,620 |
Filed: |
November 14, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
220323 |
Jan 24, 1972 |
03887964 |
Jun 10, 1975 |
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Current U.S.
Class: |
425/562; 425/147;
425/236; 425/572; 425/576 |
Current CPC
Class: |
A22C
7/0084 (20130101) |
Current International
Class: |
A22C
7/00 (20060101); A22C 007/00 () |
Field of
Search: |
;17/32,35,36,37,38,39,40
;425/236,240,241,147 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abercrombie; Willie G.
Attorney, Agent or Firm: Kinzer, Plyer, Dorn &
McEachran
Claims
I claim:
1. A high speed food patty molding machine comprising:
a multiple-cavity, cyclically operable molding mechanism
.Iadd.which requires a given volume of food material in each cycle
of operation, the molding mechanism .Iaddend.having an inlet for
supplying food material simultaneously to all of the cavities, the
molding mechanism inlet being closed for a major portion of each
molding cycle;
two food pumps, each pump comprising a fixed cavity having an
intake opening at one end and an outlet opening at the other end, a
plunger aligned with the intake end of the cavity, and drive means
for moving the plunger between a retracted ready position clear of
the intake opening in the cavity and a pressure position in which
the piston is advanced inwardly of the cavity beyond the intake
opening toward the outlet opening;
supply means for supplying moldable food material to the intake
opening of each pump cavity whenever the plunger for that pump is
in its retracted position;
a manifold connected to the outlet openings of the two pump
cavities and having an outlet passageway connected to the molding
mechanism inlet to supply a substantially unrestricted flow of food
material thereto;
actuating means for actuating the pump drive means in overlapping
alternation so that at least one pump cavity always contains
moldable food material under a given minimum mold-filling pressure
and, when the material in one cavity reaches a given minimum
volume, both pump cavities contain moldable food material under the
aforesaid mold-filling pressure for a limited pump changeover
interval;
.[.and.]. valve means for sealing off the outlet opening of each
pump cavity from the manifold whenever the plunger for that pump is
moved toward its retracted position, in an overlapping cycle such
that both outlet openings communicate with the inlet to the molding
mechanism during a part of said changeover interval, thereby
affording a continuous supply of moldable food material, under
continuous pressure, at the inlet of the molding
mechanism.[...]..Iadd.; .Iaddend.
.Iadd.the capacity of each food pump cavity being several times
said given volume so that each pump supplies the molding mechanism
for a plurality of molding cycles without requiring an intake of
additional food material;
and the drive means for each food pump comprising a fluid pressure
actuated power cylinder and a piston which advances the plunger and
the food material in the food pump cavity during a part of each
mold cycle in which the mold fills with food material and stalls
against the food material trapped in the food pump cavity during a
part of each mold cycle after the mold is filled. .Iaddend.
2. A high speed food patty molding machine, according to claim 1,
in which the valve means is incorporated in the manifold and
comprises:
a valve cylinder extending across the outlet openings of both food
pumps, the valve cylinder including at least one inlet opening for
receiving food material from the food pumps and an outlet opening
communicating with the manifold outlet passageway;
and a valve actuator for rotating the valve cylinder between a
first angular position in which food material is pumped from a
first pump into the valve cylinder and out through the manifold
outlet passageway to the molding mechanism, an intermediate angular
position in which food material is pumped simultaneously from the
first pump and a second pump into the valve cylinder and out
through the manifold outlet passageway to the molding mechanism,
and a second angular position in which food material is pumped from
the second pump into the valve cylinder and out through the
manifold outlet passageway to the molding mechanism.
3. A high speed food patty molding machine, according to claim 2,
in which the food pumps are positioned side-by-side, in which the
valve cylinder includes two inlet openings, one for each pump,
longitudinally displaced relative to each other and angularly
displaced relative to the pump cavity outlets, and in which the
outlet opening of the valve cylinder is an elongated longitudinal
slot, angularly skewed relative to the manifold outlet passageway
to balance the rate of feed to the molding mechanism for food
material pumped from both pumps.
4. A high speed .[.foot.]. .Iadd.food .Iaddend.patty molding
machine, according to claim 1, in which the supply means comprises
a hopper for receiving food material, a conveyor for conveying the
food material to one end of the hopper adjacent the intake openings
of the food pumps, and a plurality of feed devices for feeding the
food material to the intake openings of the food pumps in
synchronism with the operation of the pumps.
5. A high speed food patty molding machine, according to claim 4,
in which the conveyor comprises a belt forming the bottom of the
hopper, a conveyor drive for driving the conveyor belt, and sensing
means for interrupting the conveyor drive whenever the moldable
food material accumulated at said one end of the hopper exceeds a
given level. .[.6. A high speed food patty molding machine
according to claim 1 in which the molding mechanism requires a
given volume of food material in each cycle of operation, and in
which the capacity of each food pump cavity is at least several
times that given volume, so that each pump can supply the molding
mechanism for a plurality of operational molding cycles without
requiring an intake of additional food material..]..[.7. A high
speed food patty molding machine, according to claim 6, in which
the drive means for each food pump comprises a fluid pressure
actuated power cylinder and a piston which advances the plunger and
the food material in the food pump cavity during a part of each
mold cycle in which the mold fills with food material and stalls
against the food material trapped in the food pump cavity during
a
part of each mold cycle after the mold is filled..]. 8. A high
speed food patty molding machine, according to claim .[.7.].
.Iadd.1.Iaddend., in which the drive means for each fluid pump
includes a low-pressure fluid supply for advancing the piston and
plunger to an initial pumping position, a high-pressure fluid
supply for advancing the piston and plunger beyond the initial
pumping position, and changeover means for automatically changing
over from the low-pressure supply to the high-pressure supply in
response to the plunger stalling against food
material trapped in the pump cavity. 9. A high speed food patty
molding machine, according to claim 8, in which the changeover
means for each pump comprises a pressure-sensing device, connected
to the power cylinder, for sensing a build-up of pressure in the
cylinder when the pump plunger stalls against food material in the
pump cavity while the piston is being
advanced by the low-pressure supply. 10. A high speed food patty
molding machine, according to claim 9, in which the valve means is
actuated to seal off one pump cavity from the manifold and open the
other pump cavity to the manifold, and in which the plunger for
said one pump is retracted to its ready position, in response to
sensing of high pressure in both
power cylinders. 11. A high speed food patty molding machine,
according to claim 1, in which the food pump cavities and the
manifold comprise a common housing that includes the molding
mechanism inlet, and in which the molding mechanism comprises:
a sliding multi-cavity mold plate mounted on that housing for
reciprocal movement between a filling position at which the mold
cavities are aligned with the molding mechanism inlet and a
discharge position at which the mold cavities are clear of the
housing;
a mold cover positioned over the mold plate;
a knockout mechanism mounted on the mold cover;
and power-driven means for elevating the mold cover and knockout
mechanism clear of the mold plate to allow cleaning of the molding
mechanism and
replacement of the mold plate. 12. A high speed food patty molding
machine, according to claim 1, in which said molding mechanism
comprises a reciprocating mold plate, a crank drive for actuating
the mold plate between filling and discharge positions, and a
hydraulic cushion device incorporated in the crank drive.
Description
BACKGROUND OF THE INVENTION
Increasing use of pre-processed foods, both in homes and in
restaurants and other group eating establishments, has created a
continuously growing demand for high-capacity automated food
processing equipment. That demand is particularly evident with
respect to hamburgers, molded steaks, fish cakes, and other molded
food patties. A single drive-in restaurant may serve hundreds or
even thousands of hamburgers and other molded food patties each
day; a group of such restaurants in a metropolitan area, using a
single source of supply, may require many thousand patties
daily.
Available automated food patty molding equipment is not well
adapted to current high-volume demands. With available equipment, a
single food processor may require a large number of molding
machines to fulfill his sales requirements. A changeover from the
patty size of one customer to that of another, especially if
coupled with some difference in the specification for the meat or
other moldable food, leads to an inordinate time loss, dissipated
in machine set-up time.
Pumping mechanisms for automated food patty molding machines are a
source of several operational and maintenance difficulties. The
moldable food tends to clog or to "bridge" in the feed apparatus,
producing non-uniform patties. Food may collect in the feed
mechanism, producing possible spoilage problems. Commonly used
non-yielding compressors such as paddle pumps, synchronized with
the molding mechanism, often produce a non-uniform feed pressure.
The filling pressure fluctuates with machine timing, product
viscosity, and the quantity of product that falls in front of the
paddles in each cycle; as a result, the mold cavities may be
over-filled or under-filled on any given stroke.
Yielding compressors, as used in some conventional machines,
utilize springs to back up the food compression pumps; the spring
force pushes the food into the mold cavities. On each cycle of the
molding mechanism, the compressor opens to receive more food
material. The amount of food material captured varies the degree of
spring compression, and thus varies the filling pressure, so that
underfilling or over-filling may occur. A product exhibiting poor
flow characteristics is also difficult to feed into the compression
system. Consequently, when full pressure is most needed, it is
likely to be unavailable, producing an inconsistent product.
Variation in the pumping pressure to compensate for food material
differences may be necessary to obtain a uniform product.
Non-yielding paddle pumps often produce inadequate pressures on
low-viscosity food materials and excessively high pressures when
the material viscosity is high, as when the material is too cold or
too dry. Spring adjustment can compensate for some of these
differences, in known yielding compression systems, but the range
of adjustment is limited, and effective adjustment is often quite
difficult for the operator to achieve. The synchronized pumps of
both types produce excessive noise levels, often extremely
uncomfortable for operating personnel.
SUMMARY OF THE INVENTION
It is a principal object of the present invention, therefore, to
provide a new and improved automated food patty molding machine
capable of producing uniform molded food patties at a higher rate
of production than practical or attainable with previously known
equipment.
A more specific object of the invention is to provide a new and
improved pumping system for a high speed food patty molding machine
that consistently and continuously feeds hamburger or other
moldable food material to the molding mechanism of the machine at a
high feed rate at substantially uniform pressure. A particular
feature of the invention, in this regard, is the provision of a
slow-moving large capacity food material pumping system that can
compress and pump enough material for several molding cycles while
additional material is being received and pressurized for
subsequent cycles.
Another object of the invention is to provide a new and improved
high speed food patty molding machine that is inherently subject to
only minimal wear, in operation, and that requires no more than
minimal maintenance.
A further object of the invention is to afford a new and improved
high speed food patty molding machine that can be rapidly set up
for molding of a new product.
An additional object of the invention is to provide a new and
improved high speed patty molding machine that is inherently quiet
in operation.
A specific object of the invention is to provide a new and improved
high speed food patty molding machine that is simple and
inexpensive in construction, and that can be readily disassembled
for cleaning of the machine.
Accordingly, the invention relates to a high speed food patty
molding machine comprising a molding mechanism having an inlet for
receiving moldable food material. The machine further comprises at
least two food pumps, each pump including a pump cavity having an
intake opening and an outlet opening, a plunger aligned with the
cavity, and drive means for moving the plunger between a retracted
position clear of the intake opening in the cavity, and a pressure
position in which the plunger is advanced inwardly of the cavity,
beyond the intake opening, toward the outlet opening. Supply means
are provided for supplying moldable food material to the intake
opening of each pump cavity whenever the plunger for that pump is
in its retracted position. A manifold connects the outlet openings
of the two pump cavities to the inlet of the molding mechanism.
Actuating means are provided to actuate the pump drive so that at
least one pump cavity always contains moldable food material under
pressure. Valve means are incorporated in the manifold to seal off
the outlet opening of each pump cavity from the manifold whenever
the plunger for that pump is moved toward its retracted position,
thereby affording a continuous supply of moldable food material,
under pressure, to the inlet of the molding mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a high speed food patty molding
machine constructed in accordance with a preferred embodiment of
the present invention;
FIG. 2 is a partial plan view taken approximately along line 2--2
of FIG. 1;
FIG. 3 is an outlet end view taken as indicated by line 3--3 in
FIG. 1;
FIG. 4 is a sectional elevation view of the pumping apparatus for
the food patty molding machine, taken approximately along line 4--4
of FIG. 3;
FIG. 5 is a sectional plan view of the pumping apparatus taken
approximately as indicated by line 5--5 of FIG. 1;
FIG. 5A is a detail view, like a segment of FIG. 5, illustrating a
change in operating condition;
FIG. 6 is a detail sectional elevation view of the pump feed
manifold taken approximately as indicated by line 6--6 of FIG.
5;
FIG. 6A is a detail plan view of the pump feed manifold for the
operating condition of FIG. 6;
FIG. 7 is a detail perspective view of the valve cylinder
incorporated in the pump manifold;
FIGS. 8 and 9 are detail sectional views, showing one operating
condition for the pump manifold, taken approximately along lines
8--8 and 9--9 in FIG. 6;
FIG. 10 is a view like FIG. 6, but showing the pump manifold in a
different operating condition;
FIG. 10A is a view like FIG. 6A, but illustrating the operating
condition of FIG. 10;
FIGS. 11 and 12 are detail sectional views taken approximately
along lines 11--11 and 12--12 in FIG. 10;
FIG. 13 is a simplified elevation view illustrating the drive for
the molding mechanism of the patty molding machine;
FIG. 14 is a sectional elevation view of the knockout drive and a
part of the mounting apparatus for the molding mechanism of the
patty molding machine;
FIG. 15 is a detail view, partly in cross section, of a part of the
molding mechanism in a position utilized during change of a mold
plate;
FIG. 16 is a detail plan view, partly in cross section, of the
molding mechanism.
FIG. 17 is a sectional elevation, taken approximately along line
17--17 in FIG. 4, illustrating the supply apparatus for supplying
moldable food material to the pumps of the patty molding machine;
and
FIG. 18 is a schematic diagram of the hydraulic actuating system
employed in operation of the patty molding machine.
DESCRIPTION OF THE PREFERRED EMBODIMENT
THE GENERAL ORGANIZATION AND OPERATION OF THE PATTY MOLDING MACHINE
(FIGS. 1, 2 and 3)
The high speed food patty molding machine 20 illustrated in FIGS.
1, 2 and 3 comprises a preferred embodiment of the invention.
Molding machine 20 includes a machine base 21, preferably mounted
upon a plurality of rollers or wheels 22. The wheels 22 may rest
upon a floor; however, because of the size and weight of machine
20, it is usually preferable to use flanged wheels and to support
the machine upon rails 23 as shown in FIGS. 1 and 3. Machine base
21 supports the operating mechanism for machine 20, and contains
hydraulic actuating systems, electrical actuating systems, and most
of the machine controls.
Molding machine 20 includes a supply means 24 for supplying a
moldable food material, such as ground beef, fish, or the like, to
the processing mechanisms of the machine. As generally illustrated
in FIGS. 1 and 3, supply means 24 comprises a large food material
storage hopper 25 that opens into the intake of a food pump system
26. The food pump system 26 includes at least two food pumps,
described in detail hereinafter, that continuously pump food, under
pressure, into a manifold 27 connected to a cyclically operable
molding mechanism 28. Molding mechanism 28 is provided with an
elevator system for use in changing the molding mechanism from one
product to another, as described in detail hereinafter.
In the operation of machine 20, a supply of ground meat or other
moldable food material is dumped into hopper 25 from overhead. In
the illustrated construction, hopper 25 is comparable in size to a
conventional bathtub, and, accordingly, can hold a large supply of
moldable food material (800 to 1000 lbs.). The floor of hopper 25
comprises a conveyor belt 31, seen in FIG. 1, for moving the food
material longitudinally of the hopper toward the other components
of the food material supply means 24.
At the forward end of hopper 25, the righthand end of the hopper as
seen in FIG. 1, the food material is fed downwardly by supply means
24 into the intake of the reciprocating pumps constituting pumping
system 26. The pumps of system 26 operate in overlapping alteration
to each other; at any given time when machine 20 is in operation at
least one of the pumps is forcing food material under pressure into
the intake of manifold 27.
The manifold 27 comprises a valving system for feeding the food
material, still under relatively high pressure, into the molding
mechanism 28. Molding mechanism 28 operates on a cyclic basis,
first sliding a multi-cavity mold plate 32 into receiving position
over manifold 27 and then away from the manifold to a discharge
position aligned with a series of knockout cups 33. When mold plate
32 is at its discharge position, knockout cups 33 are driven
downwardly, discharging the hamburgers or other molded products
from machine 20, as indicated by arrow A in FIG. 1.
THE FOOD SUPPLY MEANS
(FIGS. 4, 5 and 17)
The food supply means 24 and associated hopper 25 are illustrated
in FIGS. 4, 5 and 17. As seen therein, conveyor belt 31 extends
completely across the bottom of hopper 25, around an end roller 35
and a drive roller 36, the lower portion of the belt being engaged
by a tensioning idler roll 37. A chain drive 40 (FIG. 17) is
provided for drive roller 36, driven by an electric motor (not
shown). In FIG. 4 a limited supply of meat 38 is shown present in
hopper 25. A much greater supply of meat could be stored in hopper
25 without exceeding its capacity.
The forward end of hopper 25 communicates with a vertical pump feed
opening 39 that leads downwardly into a pump intake chamber 41
(FIGS. 4, 17). A U-shaped frame 42 is mounted on machine base 21,
extending over hopper 25 adjacent the lefthand side of the hopper
outlet 39 (FIG. 4). A mounting bracket 43 is affixed to the upper
portion of frame 42, extending over the pump feed opening 39 in
hopper 25.
As shown in FIG. 17, three electric feed screw motors 45, 46 and 47
are mounted upon bracket 43; gear-motors are preferably employed.
Motor 45 drives a feed screw 51 that extends downwardly through
opening 39 in alignment with a pump plunger 88. Motor 46 drives a
centrally located feed screw 52, whereas motor 47 drives a third
feed screw 53, located at the opposite side of hopper 25 from screw
51 and aligned with another pump plunger 68.
A level sensing mechanism is located at the outlet end of hopper 25
and comprises a pair of elongated sensing elements 54, 55 extending
downwardly from a shaft 56. As the moldable food material 38 is
moved forwardly in the hopper 25 (FIG. 4), it may accumulate to a
level at which it engages the depending sensing fingers 54 and 55.
When this occurs, shaft 56 is rotated and actuates a limit switch
to interrupt the drive for roller 36 of conveyor 31. In this manner
the accumulation of meat or other food material at the outlet end
39 of hopper 25 is maintained at a safe level.
When machine 20 is in operation, the feed screw motors 45 and 46
are energized whenever plunger 88 is withdrawn to the position
shown in FIG. 5, so that feed screws 51 and 52 supply meat from
hopper 25 downwardly through opening 39 and into one side of the
intake 41 of the food pumping system 26. Similarly, motors 46 and
47 actuate feed screws 52 and 53 to feed meat to the other side of
intake 41 whenever plunger 68 is withdrawn. In each instance, the
feed screw motors are timed to shut off shortly after the plunger
is fully retracted, avoiding excessive agitation of the meat. As
the supply of food material in the outlet 39 of hopper 25 is
depleted, conveyor belt 31 continuously moves the food forwardly in
the hopper and into position to be engaged by feed screws 51-53. If
the level of meat at the outlet end 39 of hopper 25 becomes
excessive, conveyor 31 is stopped, as described above, until the
supply at the hopper outlet is again depleted. The wall of the
hopper outlet 39 immediately below conveyor drive roller 36
comprises a belt wiper blade 57 that continuously engages the
surface of belt 31 and prevents leakage of the meat or other food
material 38 from the hopper at this point.
THE FOOD PUMP SYSTEM (FIGS. 4, 5, 5A and 6)
The food pump system 26 of molding machine 20 is best illustrated
in FIGS. 4 and 5. As shown therein pump system 26 comprises two
reciprocating food pumps 61 and 62 mounted upon the top 63 of
machine base 21. The first food pump 61 includes a hydraulic
cylinder 64 having two ports 65 and 66. The piston in cylinder 64
(not shown) is connected to an elongated piston rod 67; the outer
end of piston rod 67 is connected to a large plunger 68. Plunger 68
is aligned with a first pump cavity 69 formed by a pump cavity
enclosure 71 that is divided into two chambers by a partial central
divider wall 72. The forward wall 74 of pump cavity 69 has a
relatively narrow slot 73 (FIGS. 5 and 6) that communicates with
the pump manifold 27 as described more fully hereinafter.
The second food pump 62 is essentially similar in construction to
pump 61 and comprises a hydraulic cylinder 84 having ports 85 and
86. Cylinder 84 has an elongated piston rod 87 connected to a
massive plunger 88 that is aligned with a second pump cavity 89 in
housing 71. The forward wall 94 of pump cavity 89 includes a narrow
elongated slot 93 (FIGS. 5 and 6) communicating with manifold
27.
An elongated control rod 75 is affixed to the first pump plunger 68
and extends parallel to piston rod 67 into alignment with a pair of
limit switches 76 and 77. A similar control rod 95 is fixed to and
projects from plunger 88, parallel to piston rod 87, in alignment
with a pair of limit switches 96 and 97. Limit switches 76, 77, 96
and 97 comprise a part of the control for the two pumps 61 and 62,
and are discussed more fully hereinafter in connection with FIG.
18.
In FIGS. 4 and 5, the pumping system 26 is illustrated with the
first pump 61 pumping the moldable food material into manifold 27
and with the second pump 62 receiving a supply of the moldable food
material for a subsequent pumping operation. Pump 61 has just begun
its pumping stroke, and has compressed the food product in pump
cavity 69, forcing the moldable food material through slot 73 into
manifold 27. As operation of molding machine 20 continues, pump 61
advances plunger 68 to compensate for the removal of food material
through manifold 27, maintaining a relatively constant pressure on
the remaining food in chamber 69.
As plunger 68 advances, the corresponding movement of control rod
75 ultimately trips limit switch 76, indicating that plunger 68 is
near the end of its permitted range of travel. When this occurs,
pump 62 is actuated to advance plunger 88 through pump cavity 89,
compressing the food material in the second pump cavity in
preparation for feeding the food from that cavity into manifold 27.
The pressure applied through pump 62 is sensed by a pressure
sensing switch 98 connected to one port 85 of cylinder 84; a
similar pressure sensing switch 78 is incorporated in pump 61,
being connected to port 65 of cylinder 64. When the food in the
second pump cavity 89 is under adequate pressure, the input to
manifold 27 is modified to the condition shown in FIG. 5A, so that
subsequent feeding of food product to the manifold is effected from
the second pump cavity 89 with continuing advancement of plunger 88
of the second pump 62. After the manifold intake has been changed
over, pump 61 is actuated to withdraw plunger 68 from cavity
69.
Thereafter, when plunger 88 nears the end of its pressure stroke
into pump cavity 89, limit switch 96 is tripped, signaling the need
to transfer pumping operations to pump 61. The changeover process
described immediately above is reversed; pump 61 begins its
compression stroke, manifold 27 is changed over for intake from
pump 61, and pump 62 subsequently retracts plunger 88 back to the
supply position shown in FIG. 5 to allow a refill of pump cavity
89. This overlapping alternating operation of the two pumps 61 and
62 continues as long as molding machine 20 is in operation.
Pump cylinders 64 and 84 can also be actuated to retract the two
pump plungers 66 and 88 further to cleaning positions 68A and 88A
respectively. When in the cleaning position 68A and 88A, the two
plungers are completely exposed and can be thoroughly cleaned with
little or no difficulty. In addition, retraction of the plungers to
cleaning position affords convenient access to the pump cavities 69
and 89 to assure effective cleaning of this part of pump system
26.
THE PUMP FEED MANIFOLD AND VALVE SYSTEM (FIGS. 5 THROUGH 12)
The pump feed manifold 27, shown in FIGS. 5-12, comprises a
manifold valve cylinder 101 fitted into an opening 102 in housing
71 immediately beyond the pump cavity walls 74 and 94. One end wall
of valve cylinder 101 includes an externally projecting shaft 103
connected to a drive link 104, in turn connected to the end of the
piston rod 105 of a hydraulic actuator cylinder 106. Actuator 106
has two fluid ports 12 and 13. Two sensing switches 114 and 115 are
positioned adjacent piston rod 105 in position to be engaged by a
lug 116 on the piston rod.
Valve cylinder 101 includes two longitudinally displaced intake
slots 107 and 108 alignable with the outlet slots 73 and 93,
respectively, in the pump cavity walls 74 and 94. However, slots
107 and 108 are angularly displaced from each other to preclude
simultaneous communication between the manifold and both pump
cavities 69 and 89. Cylinder 101 also includes an elongated outlet
slot 109. Outlet slot 109 is angularly skewed, longitudinally of
cylinder 101, to control the outlet pressure from manifold 27 to
molding mechanism 28, as explained hereinafter. The valve cylinder
outlet slot 109 is generally aligned with a slot 111 in housing 71
that constitutes a feed passage for molding mechanism 28 (see FIGS.
6A, 8, 9, 10A, 11 and 12). The outer end of cylinder 101 is covered
by a valve guard 110 (FIGS. 2, 3).
FIGS. 5, 6, 6A, 8 and 9 illustrate the operating condition
maintained for manifold 27 whenever pump 61 is supplying food
material under pressure to molding mechanism 28. Actuator cylinder
106 has advanced piston rod 105 to the outer limit of its travel,
angularly orienting the manifold valve cylinder 101 as shown in
these figures. With cylinder 101 in this position, its intake slot
107 is aligned with the outlet slot 73 from pump cavity 69 so that
food material is forced under pressure from cavity 69 through the
interior of valve cylinder 101 and out of the valve cylinder outlet
slot 109 through slot 111 to the molding mechanism 27. On the other
hand, the second intake slot 108 of valve cylinder 101 is displaced
from the outlet slot 93 for the second pump cavity 89.
Consequently, the food material forced into the interior of valve
cylinder 101 from pump cavity 69 cannot flow back into the other
pump cavity 89.
The alignment of the cylinder outlet slot 109 and the manifold
outlet slot 111 for this operating condition is shown in FIG. 6A.
As shown therein, the end 111A of slot 111 adjacent pump cavity 69
is only narrowly open to communication with the angularly displaced
valve cylinder outlet slot 109. The opposite end 111B of slot 111
is fully open to slot 109. Communication between the two slots 109
and 111 varies progressively from one end to the other. The slot
restriction at end 111A is affected because this is the point of
least resistance to flow of food material from pump chamber 69 to
molding mechanism 28. The much wider slot opening at end 111B is
utilized to compensate for the greater length of pump feed, and
hence greater resistance, in filling mold cavities at end 111B from
pump cavity 69.
When molding machine 20 changes over from pump 61 to pump 62 (FIGS.
5 to 5A), manifold 27 is actuated to its alternate operating
condition as illustrated in FIGS. 10-12. This is accomplished by
actuator 106, which retracts piston rod 105 to the piston shown in
FIG. 12 and rotates valve cylinder 101 through a limited angle in a
clockwise direction from the positions illustrated in FIGS. 8 and 9
from those shown in FIGS. 11 and 12.
In this alternate operating condition, intake slot 107 of cylinder
101 is displaced from the first pump cavity outlet slot 73 (FIGS.
10 and 11) so that food material can no longer flow into or out of
cylinder 101 from pump cavity 69. On the other hand, the other
intake slot 108 of cylinder 101 is now aligned with the outlet slot
93 from pump cavity 89, so that food material is forced under
pressure through slots 93 and 108 into the interior of cylinder 101
and out of the cylinder through slots 109 and 111 to the molding
mechanism of the machine.
The alignment of slots 109 and 111 for this second operating
condition, in which the food material is pumped by the second pump
62, is shown in FIG. 10A. As seen therein, the end 111A of slot 111
most remote from pump chamber 89 is wide open to compensate for the
necessity of pumping food material the full length of cylinder 101
before the material is discharged to the molding mechanism. The
other end 111B of the feed slot for the molding mechanism is quite
restricted; this is the area of least resistance for movement of
the food material. As before, the communication between slots 109
and 111 varies progressively throughout the lengths of the slots,
affording effective compensation for the variations in length of
food material flow path, and hence in resistance to flow, in
feeding the molding mechanism.
When pumping from cavity 89 of pump 62 is subsequently terminated,
and pumping is resumed from cavity 69 of pump 61 as described
above, hydraulic actuator 106 again operates to extend piston rod
105. The movement of rod 105, through link 104, rotates valve
cylinder 101 counterclockwise back to the position shown in FIGS.
6, 8 and 9. This restores manifold 27 to the appropriate operating
condition for pumping of food material from cavity 69 to the
molding mechanism of the machine.
THE MOLDING MECHANISM FIGS. 2-4 AND 13 THROUGH 16
The basic molding mechanism 28 of molding machine 20 is generally
conventional in many respects, but incorporates unusual structural
features utilized for rapid change-over of the mold plate and for
effective and efficient cleaning of the molding mechanism. FIGS. 13
through 16 illustrate the structural features of the invention
provided for these purposes, omitting some of the more conventional
parts of the mechanism that are not necessary to an understanding
of the inventive construction.
The upper surface of the housing 71 that encloses the pump cavities
69 and 89 and the manifold 27 comprises a support plate 121 that
projects forwardly of the housing, and that affords a flat, smooth
mold plate support surface. The mold plate support 121 may be
fabricated as a separate plate bolted to or otherwise fixedly
mounted upon housing 71. It includes the upper portion of the
manifold outlet passage 111, as shown in FIGS. 8, 9, 11 and 12.
Mold plate 32 is supported upon plate 121. Mold plate 32 includes a
plurality of individual mold cavities 126 extending across the
width of the mold plate and alignable with the manifold outlet
passageway 111, as shown in FIG. 14. A cover plate 122 is disposed
immediately above mold plate 32, closing off the top of each of the
mold cavities 126. A housing 123 is mounted upon cover plate 122.
The spacing between cover plate 122 and support plate 121 is
maintained equal to the thickness of mold plate 32 by support
spacers 124 mounted upon support plate 121; cover plate 122 rests
upon spacers 124 when the molding mechanism is assembled for
operation, as shown in FIG. 3. Cover plate 122 is held in place by
four mounting bolts 125 (FIGS. 2, 4, 16).
Mold plate 32 is connected to a drive rod 128 (FIG. 13) that
extends alongside housing 71 and is connected at one end to a swing
link 129. The other end of link 129 is pivotally connected to a
rocker arm 131 which, with a second arm 132, forms a crank pivoted
on a fixed shaft 133. The free end of crank arm 132 is provided
with a lost motion connection, entailing a pin 134 in an elongated
slot 135, to a connecting rod assembly 136 that includes a
hydraulic shock absorber 137. Shock absorber 137 is connected to a
mold plate crank arm 138 having a crank pin 139 linked to the
output shaft 141 of a gear reducer 142. Gear reducer 142 is driven
through a variable speed drive, represented in FIG. 13 by a pulley
143, actuated by a mold plate drive motor (not shown).
Molding mechanism 28 further comprises a knockout apparatus shown
in FIGS. 14, 15 and 16. The knockout apparatus comprises the
knockout cups 33, which are affixed to a carrier bar 145 that is
removably mounted upon a knockout support member 146. Knockout cups
33 are coordinated in number and size to the mold cavities 126 in
mold plate 32; there is one knockout cup 33 aligned with each mold
cavity 126 and the mold cavity size is somewhat greater than the
size of an individual knockout cup.
Knockout support member 146 is carried by two knockout rods 147.
Each knockout rod 147 is disposed in an individual housing 148 and
is pivotally connected to its own knockout rocker arm 149 (FIGS. 14
and 15).
As shown in FIGS. 14 and 16, each knockout rocker arm is pivotally
mounted upon a shaft 151. There a pair of springs 152 are connected
to each knockout rocker arm 149, biasing the arm toward movement in
a clockwise direction as seen in FIG. 14. Clockwise movement of
each rocker arm 149 is limited by a stop 153 aligned with a bumper
154 mounted in housing 123.
Each rocker arm 149 is normally restrained against counterclockwise
movement by engagement with a knockout cam 155 (FIGS. 14, 16); the
two cams 155 each have a notch 156 aligned with the corresponding
notch on the other cam. Cams 155 are affixed to a knockout cam
shaft 157. Shaft 157 extends across housing 123 to a right angle
drive connection 158 leading to a knockout cam drive shaft 159
(FIG. 15) that has a driving connection (not shown) to the mold
plate drive gear reducer output shaft 141 (FIG. 13).
Two cover lift bars 161 and 162 are affixed to cover plate 122 on
opposite sides of the machine (FIGS. 14-16) and extend downwardly
into machine base 21. As shown in FIG. 14, the lower end of lift
bar 162 comprises a rack 163 that engages a pinion 164 on one end
of a shaft 165. Lift bar 161 comprises a similar rack engaging a
pinion 166 on the opposite end of shaft 165. Shaft 165 carries a
sprocket 167 engaged by a chain 168 driven from a reversing mold
cover lift motor 169, which is preferably a gear motor.
During a molding operation the molding mechanism 128 is assembled
as shown in FIGS. 13 and 14, with cover plate 122 tightly clamped
onto spacers 124 as illustrated in FIG. 3. Gear reducer 142 (FIG.
13) is continuously driven through pulley 143.
Starting from the position shown in FIG. 13, in each cycle of
operation, knockout cups 33 are first withdrawn to the position
shown in FIG. 14, cams 155 pivoting knockout rocker arms 149 to
their elevated positions to lift the knockout cups. The drive
linkage from gear reducer 142 to mold plate 32 (FIG. 13) then
slides the mold plate from the full extended position shown in FIG.
13 to the mold filling position illustrated in FIGS. 4 and 14, with
the mold cavities 126 aligned with passageway 111.
In the retracted cavity filling position for mold plate 32, drive
rod 128 is in the dash line position 128A, FIG. 13; the other drive
components are in the positions indicated by swing link 129A, crank
arms 131A and 132A, and connecting rod 136A. The lost motion
connections in the drive linkage assure some dwell time at the
discharge or knockout position (FIG. 13) of mold plate 32, so that
the knockout cups 33 have time to enter and leave the mold cavities
126 while mold plate 32 is at rest. Some dwell at the cavity
filling position may also be provided. Hydraulic cushion 137 allows
crank 131 to pick up the mold plate load over several degrees of
rotation, gradually overcoming the mold plate inertia. The lost
motion connections and the hydraulic cushion 137 incorporated in
the drive linkage for the mold plate thus reduce wear and tear on
both the mold plate and its drive, assuring long life and minimum
maintenance.
During most of each cycle of operation of mold plate 32, the
knockout mechanism illustrated in FIGS. 14-16 remains in the
elevated position, FIG. 14, with knockout cups 33 clear of mold
plate 32. When mold plate 32 reaches its extended discharge
position as shown in FIG. 13, however, the notches 156 in the cams
155 are brought into alignment with the knockout rocker arms 149
(FIG. 14). Synchronism is maintained between cams 155 and mold
plate 32 because knockout cam shaft 157 is driven directly from the
same gear reducer 142 that drives the mold plate. At this point in
the molding cycle, the two knockout rocker arms 149 are pulled
rapidly downwardly by the springs 152, pivoting the two rocker arms
in a clockwise direction. This movement of the rocker arms drives
the knockout rods 147 downwardly, moving the knockout cups 33
through the mold cavities 126 to discharge molded food patties,
such as the patty 171, from the mold plate 32 (see FIG. 13). The
discharged patties may be picked up by a conveyor 172 or may be
accumulated in a stacker. If desired, the discharged patties may be
interleaved with paper, by an appropriate paper interleaving
device. In fact, machine 20 may be used with a wide variety of
secondary equipment, including steak folders, bird rollers, and
other such equipment.
To change mold plate 32 or to clean molding mechanism 28, the
retaining nuts on mounting bolts 125 are removed. Motor 169 is then
energized, rotating shaft 165 in a counterclockwise direction as
seen in FIG. 14. This raises the two lift bars 161 and 162
simultaneously and lifts cover plate 122 and the entire knockout
mechanism to the position shown in FIG. 15, displaced well above
mold plate 32. When this has been done, it is a simple matter to
remove mold plate 32 for cleaning or replacement. If a different
mold plate is installed in the machine entailing a different number
of mold cavities 126, the knockout cup assembly comprising cups 33
and carrier 145 is also removed and a new knockout cup assembly
coordinated to the new mold plate is installed. When cleaning or
modification of the mold plate and knockout assembly are completed,
motor 169 is again energized for rotation in the opposite
direction, lowering the knockout mechanism and cover plate 122 to
their normal operative position. The retaining nuts are
re-installed on bolts 125 and machine 20 is again ready for
operation.
HYDRAULIC ACTUATION SYSTEM AND OVERALL SEQUENCE OF OPERATION (FIG.
18)
FIG. 18 affords a schematic illustration of a preferred form of
hydraulic actuator system 180 for the food pumps and the manifold
of patty molding machine 20; system 180 also provides a basis for
description of a typical pump-manifold operating sequence. In
system 180, port 65 of cylinder 64 in the first food pump 61 is
connected to one port 191 of a two-position control valve 181. Port
66 of cylinder 64 is connected to a second port 192 of valve 181. A
third port 193 of valve 181 is connected to a high pressure oil
line 182 that is connected to an accumulator 183 and to a
high-pressure hydraulic pump 184. Pump 184 draws hydraulic fluid
from a tank 185 through an appropriate filter 186. Valve 181 is
actuated by a solenoid 187. The remaining port 194 of valve 181 is
connected to a drain line 188 that is returned to tank 185 through
a filter 189.
Port 65 of pump cylinder 64 is also connected to one port 195 of a
three-position control valve 201, with port 66 of cylinder 64
connected to a second port 196 of valve 201. Valve 201 is a
three-position control valve actuated by two solenoids 202 and 203.
It includes a third port 197 connected to a hydraulic line 199 that
is fed from the outlet of a low pressure hydraulic pump 204 having
an intake connected to tank 185 through a filter 205. The pumps 184
and 204 are driven by a single electric motor 206. The remaining
port 198 of valve 201 is connected to a hydraulic line 207.
The controls for cylinder 84 of the second food material pump 62
are essentially identical to those of cylinder 64. Thus, port 85 of
cylinder 84 is connected to one port 221 of a two-position control
valve 211 actuated by a solenoid 217. Port 86 of cylinder 84 is
connected to a second port 222 of valve 211. The third port 223 of
valve 211 is connected to the high pressure hydraulic line 182 and
the fourth port 224 of control valve 211 is connected to the drain
line 188.
Port 85 of the second pump cylinder 84 is connected to the first
port 225 of a three-position control valve 231. Port 86 of cylinder
84 is connected to a second port 226 of valve 231. The third port
227 of valve 231 is connected to line 207 and the fourth port 228
is connected to drain line 188. Valve 231 is actuated by two
solenoids 232 and 233.
Port 112 of the manifold actuator cylinder 106 is connected to one
port 235 of a two-position control valve 234; port 113 of cylinder
106 is connected to a second port 236 of the same valve. The third
port 237 of control valve 234 is connected to the high pressure
hydraulic line 182. The fourth port 238 of valve 234 is connected
to drain line 188. Valve 234 is actuated by a solenoid 239. A
pressure relief valve 240 may be connected between the low pressure
hydraulic supply line 199 and the drain line 188. An auxiliary
accumulator 241 and variable restriction 242 are connected to the
high pressure line 182 near actuator cylinder 106.
In considering operation of patty molding machine 20, using the
hydraulic actuation and control system 180 of FIG. 18, it may be
assumed at the start that the two piston rods 67 and 87 are fully
retracted with the plungers 68 and 88 in their respective cleaning
positions 68A and 88A, (FIG. 5) and that cylinder 106 is fully
retracted as shown in FIG. 18. In these circumstances, motor 206 is
energized, starting both high pressure pump 184 and low pressure
pump 204. High pressure oil is accumulated in accumulators 183 and
241 and is supplied to port 112 of actuator cylinder 106. This
assures a start-up of machine 20 with cylinder 106 in its fully
retracted position and with manifold 27 in the operating condition
illustrated in FIGS. 10-12.
After a limited period of time, sufficient to allow a build-up of
an adequate volume of hydraulic fluid under pressure in the two
accumulators 183 and 241, the machine operator actuates a suitable
electric control (not shown) to energize solenoids 202 and 232.
This alters the porting arrangements for both of the valves 201 and
231, so that low pressure oil is supplied from line 199 to port 65
of cylinder 64, advancing piston rod 67 and plunger 68 a short
distance until control rod 75 trips limit switch 77. At the same
time, oil under low pressure is supplied, through line 207 and
control valve 231, to port 85 of the second pump cylinder 84, which
advances piston rod 87 and plunger 88 until limit switch 97 is
tripped by control rod 95. The tripping of switches 77 and 97
de-energizes solenoids 202 and 232, allowing control valves 201 and
231 to return to their initial operating conditions and
interrupting the supply of fluid to the pump cylinder ports 65 and
85. The plungers 68 and 88 are stopped side-by-side in their
respective ready positions, corresponding to the position of
plunger 88 in FIG. 5, with the leading edge of each plunger just
inside pump housing 71.
The machine operator next starts the sequential operation of
machine 20 by actuating an appropriate electrical control to
energize solenoid 202, again supplying low pressure fluid from line
199, through ports 197 and 195 of control valve 201, to port 65 of
cylinder 64 in the first food pump 61. As a consequence, piston rod
67 and plunger 68 are advanced, pushing food material into the
first pump cavity 69. After a short period of time, plunger 68
stalls against the food material trapped in cavity 69; as a result,
pressure builds up in the portion of cylinder 64 connected to port
65. This build-up of fluid pressure trips the pressure-sensitive
switch 78.
When switch 78 is tripped, solenoid 187 is energized and solenoid
202 is de-energized. Control valve 201 returns to its original
operating condition, cutting off the low-pressure fluid supply to
port 65 of cylinder 64. However, control valve 181 is to connect
the high pressure hydraulic fluid line 182 to port 65 of cylinder
64. In addition, the actuation of the pressure sensing switch 78 is
utilized to initiate energization of solenoid 239 of control valve
234. This reverses the inlet and drain connections for actuator
cylinder 106, connecting port 113 to the high pressure line 182 and
connecting port 112 to the drain line 188. Actuator cylinder 106
rapidly advances piston rod 105 to the position shown in FIGS. 5-9,
conditioning manifold 27 to feed food material from the first pump
cavity 69 to the molding mechanism 28. Plunger 68, under
compression, forces food material through the aligned ports of
manifold 27 and fills the manifold outlet passageway 111 with food
material under relatively high pressure. This action continues
until plunger 68 stalls against the food material trapped in pump
cavity 69 and in manifold 27, a condition which is reached in a
short time.
Molding mechanism 28 now begins its sequential cyclic operation.
Each time mold plate 32 comes into alignment with the manifold
outlet passageway 111, filling mold cavities 126, as described in
detail above, plunger 68 jogs forward by a short distance, pushing
additional food material forwardly in cavity 69, into manifold 27,
and into the cavities of the mold plate, and then again stalls
against the trapped food material. In this manner, plunger 68 of
food pump 61 jogs or "jumps" forwardly into cavity 69 each time the
mold cavities are filled anew.
As plunger 68 moves into cavity 69, after several cycles of the
molding mechanism, limit switch 76 is tripped by control rod 75,
signalling that plunger 68 is near the end of its stroke and that
only a minimal amount of food material remains in cavity 69. The
actuation of switch 76 energizes solenoid 232 to shift control
valve 231 and apply low pressure fluid from line 199, through line
207, to port 85 in the second pump cylinder 84. As a consequence,
plunger 88 is advanced, pushing food material into the second pump
cavity 89. After a short time, plunger 88 stalls against the food
material trapped in cavity 89, so that the oil pressure in the
portion of cylinder 84 connected to port 85 builds up and trips the
pressure-sensitive switch 98.
When switch 98 is tripped, solenoid 217 is energized to actuate
control valve 211 and solenoid 232 is de-energized, permitting
control valve 231 to return to its original operating condition.
Under these circumstances, port 85 of pump cylinder 84 is connected
to the high pressure line 182 and port 86 is connected to the drain
line 188. Accordingly, the food material in cavity 89 is placed
under high pressure.
At this point, the two pressure sensitive switches 78 and 98 have
both been tripped; this is the signal for actuation of manifold 27
to its alternate operating condition to feed molding mechanism 28
from the second pump cavity 89. Solenoid 239 is de-energized,
allowing valve 234 to return to its original operating condition as
shown in FIG. 18, with oil supplied under pressure to port 112 of
actuator cylinder 106 and with port 113 connected to drain line
188. Consequently, piston rod 106 is rapidly retracted and the
manifold valve cylinder 101 is rotated to the alternate manifold
operating condition illustrated in FIGS. 10-12. Food material can
now be pushed into the mold plate cavities by plunger 88 moving
into cavity 89.
If it happens that the mold plate cavities 126 are aligned with the
manifold outlet passageway 111 at the time valve cylinder 101 is
rotated to change over from pump 61 to pump 62, the mold cavities
will be filled with food material flowing from both of the pump
cavities 69 and 89. It should be noted that switch 76 must be
tripped soon enough to allow plunger 88 to advance and build up a
high pressure in cavity 89, and also to allow a changeover in the
position of manifold valve cylinder 101 to take over filling of the
mold cavities from pump cavity 89, before plunger 68 reaches the
end of its stroke, so there will be no interruption in the
operation of molding mechanism 28.
When the changeover of manifold 27 has been completed, by rotation
of valve cylinder 101 to the position shown in FIGS. 10-12, the
outlet slot 73 from pump cavity 69 is blocked. Accordingly, plunger
68 can now be retracted to obtain a new supply of material. The
completion of changeover operation in the position of the manifold
valve cylinder is signalled by tripping of limit switch 115;
actuation of switch 115 de-energizes solenoid 187 and permits
control valve 181 to return to its original position as shown in
FIG. 18. This disconnects the high pressure supply line 182 from
port 65 of cylinder 64 in the first food pump 61. The pressure
sensing switch 78 drops out. Solenoid 203 is energized, shifting
control valve 201 to its third operating position and connecting
the low pressure supply line 199 to port 66 of cylinder 64 while
port 65 is connected to drain line 188 through line 207. This
retracts the piston in cylinder 64 and hence retracts piston rod 67
and plunger 68 from the pump cavity 69. Retraction of plunger 68
continues until switch 77 is tripped, de-energizing solenoid 203.
This action occurs when plunger 68 reaches its ready position, just
within housing 71, allowing an additional supply of food material
to be fed into pump 61 by feed screw 52 and 53, which are actuated
while plunger 68 retracts.
Plunger 68 remains in its ready position until plunger 88 advances
by jogging or jumping to a point near the end of its travel into
pump cavity 89. When plunger 88 has moved far enough to trip
sensing switch 96, solenoid 202 is energized. With solenoid 202
energized, control valve 201 is positioned to supply oil from the
low pressure line 199 to port 65 of pump cylinder 64, advancing
plunger 68 to push a fresh supply of food material into pump cavity
69. Plunger 68 stalls against the material trapped in cavity 69, so
that a build-up of oil pressure occurs behind the piston in
cylinder 64 and again trips pressure switch 78 which connects the
high pressure hydraulic fluid line 182 to port 65 of cylinder 64 by
energizing solenoid 187.
When pressure switch 78 trips, solenoid 202 is de-energized to cut
off the low pressure oil supply to cylinder 64. The two pressure
switches 78 and 98 being energized, solenoid 239 is again energized
to reverse the valve connections for cylinder 106, supplying high
pressure oil to port 113 and connecting port 112 to drain line 188.
Accordingly, piston rod 105 is again advanced and rotates valve
cylinder 101 to change manifold 27 back to the operating condition
shown in FIGS. 5-9. Accordingly, food material can now again be
forced into the mold plate cavities, through manifold 27, by pump
61.
The changeover in manifold 27 to pump 61 again blocks the slot 93
from pump cavity 89, so that the second food pump 62 can be
re-charged with food material. The changeover of the pump manifold
trips sensing switch 114, which actuates an appropriate electrical
control circuit to de-energize solenoid 217, allowing control valve
211 to return to its original operating condition and cutting off
the high pressure oil supply to pump cylinder 84. The pressure
sensing switch 98 drops out, solenoid 233 is energized, and control
valve 231 is actuated to its third operating condition. Under these
circumstances, low pressure oil is supplied through lines 199 and
207 to port 86 of cylinder 84 while port 85 is connected to drain
line 188. Accordingly, plunger 88 is retracted to its ready
position, tripping sensing switch 97. When switch 97 is tripped,
solenoid 233 is de-energized and valve 231 returns to its original
position, the movement of plunger 88 being halted with the plunger
in its ready position as shown in FIG. 5 so that a new supply of
food material can be fed directly into pump cavity 89 by feed
screws 51 and 52 (see FIG. 5).
Plunger 88 waits in its ready position until plunger 68 jogs or
jumps ahead to the point near the end of its travel where switch 76
is tripped. Actuation of switch 76 energizes solenoid 232 to begin
a slow advance of plunger 88, thus initiating the next changeover
to the second food pump 62. Operation continues in this manner,
with pumps 61 and 62 working in overlapping alternation, as long as
an output is desired from molding machine 20 and a continuing
supply of food material is maintained in hopper 25.
The function of accumulator 241 is to minimize the pressure drop in
line 182 caused by the feeding of high pressure oil to cylinder
106. This is desirable in maintaining uniformity in the pressure at
which the mold cavities are filled just after cylinder 106 shifts.
Restriction 242 limits the flow of oil to replenish accumulator
241, minimizing the pressure drop.
The electrical control for machine 20 is preferably arranged so
that, when the machine is stopped, solenoid 239 is de-energized.
Thus, whenever the machine is stopped, high pressure oil is
supplied to port 112 of actuator cylinder 116, retracting piston
rod 105. In this manner, a "home" position is established for
actuator 106 and for manifold 27. All other control valve solenoids
are de-energized whenever the machine is stopped, so that both high
pressure and low pressure supply lines are disconnected from pump
cylinders 64 and 84.
Before machine 20 is started again, plungers 68 and 88 should be
retracted to their ready positions as exemplified by the position
of plunger 88 in FIG. 5. This can be readily accomplished by
separate controls for solenoids 203 and 233, operated in
conjunction with sensing switches 77 and 97. Preferably, separate
contacts in sensing switches 77 and 97 are used for this purpose to
avoid confusion in machine operation, relative to the normal pump
sequence control described above. Additional energizing circuits
may be provided for solenoids 203 and 233 to retract the pump
plungers to their respective cleaning positions 68A and 88A (FIG.
5).
In actuator system 180 (FIG. 18) pump 184 preferably comprises a
variable volume self-compensating pump capable of automatically
maintaining a given set pressure. A remote linkage connects pump
184 to a pressure adjustment knob 190 that is accessible to the
machine operator (FIGS. 1 and 18). In addition, the actuator system
incorporates a pressure gauge 170, in line 182, mounted on the
machine in close proximity to the adjustment knob 190. Gauge 180
can be calibrated to afford the operator a direct indication of the
molding pressure for the meat or other material being molded, since
the gauge reads the pressure of the hydraulic fluid supplied to
pumps 61 and 62.
The machine operator can select any given molding pressure by
actuating knob 190 to adjust pump 184 until the desired pressure is
indicated on gauge 170. Accumulator 183 stores enough hydraulic
fluid to keep the pressure drop minimal during filling of the mold
cavities 126. The consistent pressure applied to the molded product
in each stroke of the machine affords an excellent weight control
for the molded food patties produced by the machine. The adjustable
pressure afforded by system 180 allows the machine operator to
compensate, while machine 20 is in operation, for changes in
viscosity of the moldable food material which may be caused by
slight changes in temperature, moisture content, and other
factors.
CONCLUSION
The patty molding machine 20 is susceptible of a wide variety of
modifications while retaining the substantial advantages of the
present invention. For example, the number, size, and arrangement
of the mold cavities 126 in mold plate 32 can be varied to suit
production needs; a mold plate change and a corresponding change of
knockout cups 15 all that is necessary, and is easily accomplished
with the mold changeover system shown in FIGS. 14-16. A linear
arrangement of mold cavities 126 and a single outlet passageway 111
feeding those cavities has been illustrated, but two or even more
mold feed passageways and a corresponding arrangement of mold
cavities can be utilized if desired.
The number of feed screws 51-53 is not critical. There should be at
least one feed screw or similar device for each pump, but
additional feed screw capacity may be added as needed. Two food
pumps will ordinarily afford the most efficient pumping system, but
a larger number may be employed to take advantage of available pump
components or for other economic reasons. Pneumatic or even
mechanical drive and control apparatus can be utilized for pumps 61
and 62 and manifold 27, instead of the illustrated hydraulic
system; however, a hydraulic system is usually quieter and more
reliable.
The time cycle for the molding mechanism 28 can be established
within rather wide limits to suit production needs. A cyclic
molding rate of forty to eighty cycles per minute has been used
effectively and successfully in machine 20, affording a high
production rate and uniform product. The number of mold cycles for
each pump cycle varies in accordance with the volume of the mold
cavities. Typically, the mold cavities may be filled ten or more
times from one pump before changeover to the other pump occurs.
The electrical control system for molding machine 20 has not been
illustrated because it is not critical to the invention and can be
varied to suit the needs and desires of the user. Conventional
relay circuits are readily adaptable to the control requirements of
the machine, but more sophisticated sequence controls can be
employed. It may also be noted that the specific cylindrical valve
arrangement comprising valve cylinder 101, for manifold 27, can be
replaced by other valve structures, such as gate valves or poppet
valves. However, the tubular valve arrangement comprising cylinder
101 is highly efficient in conditioning manifold 27 for alternate
acceptance of food material, under relatively high pressure, from
the two food pumps 61 and 62, while allowing rapid and convenient
removal of all of the valve elements for cleaning, as is frequently
necessary for food processing machinery.
The food patty molding machine 20 fills its mold cavities under
uniform pressure, regardless of which of the two food pumps 61 and
62 is in operation at any given moment, so that the molded food
product of the machine is highly uniform in its weight, size, and
other characteristics. The high pressures developed by the piston
pumps incorporated in the machine, and the relatively large size of
the pumps, make it possible to use machine 20 with food material
that is of high viscosity; indeed, machine 20 is capable of
producing a uniform product even from a food material that is
partially frozen when furnished to the machine. Because the food
pumps have a much higher capacity than the molding mechanism of the
machine, and hence work on a substantially different and slower
operating cycle, molding machine 20 is much quieter and can
function at a substantially higher rate than conventional
equipment.
The number of moving parts in molding machine 20 is minimal and the
machine is capable of operating for extended periods at a high rate
of production with very limited maintenance. The changeover of
molding machine 20 from one product to another can be accomplished
in a relatively short period of time; a complete changeover
entailing different molds and an entirely different food material
requires less than five minutes. The consistent pressure applied by
pumps 61 and 62 in the molding of each group of food patties
affords precise weight control, whereas the adjustable pressure
control allows the machine operator to compensate easily for minor
changes in the viscosity of meat during an extended run. The
machine is arranged so that all heavy parts (mold cover and
plungers) are moved to their cleaning positions under power. All
moving parts projecting outwardly of cabinet 21 are rotary or
reciprocating members, so that the cabinet can be completely sealed
and does not require internal cleaning. Actually, only eight simple
parts require removal for cleaning purposes.
* * * * *