AU740983B2 - Automatic plate freezer - Google Patents

Description

-1- P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service Gordon Brothers Industries Pty Ltd John Richard MOTT in Australia: CARTER SMITH BEADLE 2-Railway Parade Camberwell Victoria 3124 Australia Invention Title: AUTOMATIC PLATE FREEZER Details of Associated Provisional Application: PO 7908 filed 16 July 1997 The following statement is a full description of this invention, including the best method of performing it known to us 2 This invention relates to an automatic plate freezer, and to a loading/unloading method therefor. It particularly relates to automatic plate freezers of the kind having a stack of substantially horizontal freezing plates defining therebetween a plurality of spaces known as freezing stations into which products to be frozen may be introduced.

Automatic plate freezers of the kind described above typically include loading means for loading the products to be frozen, pressure-applying means for applying pressure to the stack of freezing plates when loaded, and unloading means for removing the frozen products. In conventional plate freezers, the plate freezer stack is progressively opened and closed as it is unloaded and loaded. Normally, in such a method of operation, all of the stations above the station being unloaded/loaded are in the open position so that all products in those stations experience only single sided plate contact at that time. As the plate performance depends, to a large extent, on the time the products are sandwiched between two cold plates, it is desirable to maximise the amount of time the products are in contact with plates above and below.

15 According to one aspect of the present invention, there is provided an automatic plate freezer including a stack of horizontally extending freezing plates :defining therebetween a plurality of freezing stations, means for raising and lowering the stack of freezing plates relative to a support frame, loading means provided at a "level fixed relative to the support frame for loading products into the freezing stations, 20 unloading means provided at the same level fixed relative to the support frame for unloading products from the freezing stations, and latching means operable to support one or more freezing plates above the level of the loading means and unloading means, wherein the stack of freezing plates is supported on a lower plate frame which occupies a top position at the start of a loading/unloading process, the lower plate frame being lowered from the top position sequentially through a number of intermediate positions during the loading/unloading process to a bottom position for freezing, the latching means being operated at each intermediate position to support a plate or plates above the bottom plate, the lower plate frame and plate or plates supported thereon below the latching means being lowered in each intermediate 0 position when the latching means is operated to open the freezing station below the plate supported by the latching means with all the other freezing stations being closed.

The lower plate frame is adapted to be raised and lowered relative to the support frame during the loading and unloading process. The lower plate frame is adapted to be lifted from the bottom position for freezing to occupy the top position at the start of the unloading/loading process. In the top position, the latching means is operable to support the second bottom plate, and the lower plate frame and bottom plate supported thereon are lowered so that the bottom freezing station is opened at the level of the loading and unloading means with all of the plate freezing stations above being closed. The bottom freezing station can then be unloaded, if it previously contained frozen products, and loaded with fresh products to be frozen. The lower plate frame is then lifted to close the bottom freezing station and to remove the load from the latching means. Then, the latching means is released and the plate stack can be indexed down one station by lowering the lower plate frame. The latching means is then re-engaged to support the third bottom plate and the lower plate frame lowered Sto open the second bottom freezing station for unloading/loading. The process is then repeated sequentially until all of the freezing stations have been unloaded and then loaded with fresh products to be frozen. When the top freezing station has been unloaded/loaded, the lower plate frame is raised to close the top freezing station and to remove the load from the latching means. The latching means is then released and the lower plate frame is lowered into its bottom position for supporting the plate stack in 20 the freezing position. The plate freezer preferably includes clamping means for applying pressure to the stack of freezing plates when all the freezing stations of the stack are fully loaded and the plate stack is in its bottom position. In the unloading/loading process, all the freezing stations, except for the freezing station being unloaded/loaded, are closed with the products being maintained in contact with freezing plates above and below. The present invention is particularly applicable to large scale plate freezers in which the weight of the plates and products in the upper freezing stations that are not being unloaded/loaded will assist in exerting freezing pressure on products in freezing stations below. This can obviate the need for continuously applying and releasing clamping means during the unloading/loading 0 process.

-4- According to another aspect of the invention, there is provided a method of unloading/loading an automatic plate freezer having a stack of horizontally extending freezing plates defining therebetween a plurality of freezing stations, said method including the steps of: raising the stack of freezing plates from a bottom position to a top position within a fixed support frame; operating latching means to support all of the freezing plates except the bottom plate; lowering the bottom plate so that the bottom freezing station is opened at a level for unloading/loading which is fixed relative to the support frame; unloading a product from and/or loading a product into the bottom freezing station; raising the bottom plate to close the bottom freezing station and to remove the load from the latching means; releasing the latching means; and sequentially repeating the steps above for all other freezing stations that .o are required to be unloaded/loaded; wherein each time a freezing station is opened for unloading/loading, all of the other freezing stations are closed.

a particularly preferred arrangement, the freezing plates are separated by spacers fixed to and extending upwardly from the plates, and the latching means has a latching part engageable with a generally horizontally extending upper part of a spacer during the unloading/loading process. Preferably, a latching means is provided at each side of the plate stack, the latching part of each latching means being engageable with a respective spacer.

20 The means for raising and lowering the plate stack preferably comprises a lifting ram operatively connected to the lower plate frame. In a particularly preferred arrangement, the lifting ram is operatively connected to the lower plate frame via a series of belts or chains or the like extending around pulleys such that extension of the lifting ram results in a corresponding lowering of the lower plate frame, and contraction of the lifting ram raises the lower plate frame.

The unloading means and the loading means are preferably constituted by a single pushing arrangement including a pusher head that is movable horizontally from a retracted position outside the plate freezer stack into an opened freezing station of the plate freezer stack either to push frozen products out of the freezing station or to push fresh products into the freezing station. Preferably, the JRG:JA:#25225.CAP 13 July 1998 unloading/loading mechanism comprises an expandable scissor assembly.

Preferably, an infeed conveyor is provided at the front of the plate freezer stack for supplying fresh products to the unloading/loading mechanism, and an outfeed conveyor is disposed at the rear of the plate freezer stack for receiving unloaded products pushed out of the freezing stations by the unloading mechanism.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a side elevation of an automatic plate freezer in accordance with the invention with the plate stack in a first position for unloading/loading; Figure 2 is a side elevation of the plate freezer of Figure 1 with the plate ;stack in another position; Figure 3 is a front view of the plate freezer in the first position of Figure 1; Figure 4 is a front view of the plate freezer in the position of Figure 2; Figure 5 is an opposite side view of the plate freezer in the first position of Figure 1; Figure 6 is an opposite side view of the plate freezer in the position of Figure 2; Figure 7 is a section on the line A-A of Figure 5; and Figure 8 is a plan view of the plate freezer.

20 The automatic plate freezer 10 shown in the drawings includes a stack of horizontal freezing plates 20, an infeed conveyor 12 passing along the front of the plate freezer stack, an outfeed conveyor 14 passing along the rear of the plate freezer stack, and a loading/unloading assembly 16 for loading and unloading the plate freezer with products.

The stack of horizontal freezing plates 20 is supported for vertical movement relative to a support frame structure 30. The support frame structure 30 has a substantially horizontal, rectangular base frame assembly 32, four column frame members 34 extending substantially vertically from the corners of the base frame assembly 32, and a substantially horizontal, rectangular top frame assembly 36 mounted on the upper end of the column frame members 34.

JRG:JA:#25225.CAP 13 July 1998 -6- Each freezing plate 20 of the plate freezer stack has an upper plate member 21 and a lower plate member 22 spaced apart by a short distance so as to define a chamber 23 for receiving a refrigerant fluid such as liquid ammonia. A spacer 24 is fitted to each side of the upper plate member 23 of each freezing plate 20. Each spacer 24 is generally C-shaped in cross-section having upper and lower flanges 26 extending substantially horizontally and outwardly from a substantially vertical member 27. The lower flange 26 is fixed to the upper plate member 21 of a freezing plate 20 below the spacer 24, and the upper flange provides a support for a freezing plate above. The spaces between adjacent freezing plates 20 above and below the spacers form freezing stations 28 for receiving the product to be frozen "which are conveniently contained in cartons having a height corresponding to the height of the spacers 24.

-The bottom plate 20' of the plate freezer stack is supported on a lower plate oooframe 40 and the top plate 20" is secured to an upper plate frame 42. The lower plate frame 40 supporting the plate stack is adapted to be raised or lowered relative to the support frame 30 by a lifting arrangement which will now be described with particular reference to Figures 1 to 4 and 8.

Four lifting chains 44 are secured to and extend vertically upwards from the corners of the lower plate frame 40. Each lifting chain 44 extends around a first I" 20 pulley 46 at a respective corner of the top frame assembly 36 and horizontally to a respective second pulley 48. As shown in the plan view of Figure 8, the second pulleys 48 are supported on a side extension 38 of the top frame assembly 36 at one side of the plate freezer. The four lifting chains 44 extend around the respective second pulleys 48 and downwardly to a connecting element 45. Two further belts or chains 54 are secured to the connecting elements 45 and extend downwardly to respective third pulleys 52. The belts or chains 54 then extend upwardly to a horizontally extending beam 56 which is fixedly attached to the column frame members 34 on said one side of the plate freezer. A similar beam 57 is secured to the column frame members 34 at the same level on the other side of the plate freezer. The third pulleys 52 are mounted on a platform 58 which is vertically RG:JA:#25225.CAP 13 July 1998 -7moveable relative to the support frame structure 30. The platform is secured to the upper end of a piston rod 62 of a lifting ram assembly 60. The lower part of the piston rod 62 is vertically moveable within a cylinder 64 of the lifting ram assembly which may be operable hydraulically.

Operation of the lifting ram assembly 60 to extend the piston rod 62 raises the platform 58 and results in a corresponding lowering of the lower plate frame and the plate stack supported thereon. Conversely, operation of the lifting ram assembly 60 to contract the piston rod 62 into the cylinder 64, lowers the platform 58 and results in a corresponding raising of the lower plate frame 40 and the plate stack supported thereon.

As shown in the drawings, the plate freezer 10 has thirteen freezing stations 28, but it will be appreciated that the number of freezing stations 28 and the height of the stations defined by the spacers 24 may vary for different requirements and for different food products to be frozen. However, the number of freezing stations will preferably be between 10 and 25. In a particularly preferred embodiment, each plate 20 has a width from side to side of approximately 3120 mm designed to accommodate eight cartons side-by-side of a width of about 380 mm each, and a length from front to back of approximately 4125 mm designed to accommodate seven cartons of a length of about 580 mm each giving a total of 56 cartons per 20 freezing station.

Preferably, an automatic plate freezing installation is provided having a plurality of plate freezers disposed next to one another, with a common infeed conveyor 12 disposed along one side of the plate freezers and a common outfeed conveyor 14 disposed along the opposite side of the plate freezer. In one preferred arrangement, four plate freezers are designed to suit cartons of approximately 165 mm in height and one plate freezer unit is designed to suit a carton height of approximately 110 mm. This plate freezer may have its own dedicated loading/unloading assembly 16, and the other plate freezers may share one or more mobile loading/unloading assemblies 16 moveable along the infeed conveyor in a sideways direction from a position in front of one plate freezer to a position in front JRG:JA:#25225.CAP 13 July 1998 -8of another plate freezer. Each loading/unloading assembly 16 has a pusher head 66 extending across the full width of the front of the freezing stations 28 and moveable by an expandable scissor mechanism 68 across the infeed conveyor 12 and the entire length of a freezer plate 20 from front to back either to push cartons from the infeed conveyor 12 into a freezing station 28 or to push frozen cartons from a freezing station 28 onto the outfeed conveyor 14.

As described above, the plate stack is moveable vertically relative to the support frame 30 so that each freezing station 28 can progressively align with the common load/unload level at which the loading/unloading assembly 16 and infeed and outfeed conveyors 12 and 14 are disposed.

"Each freezer plate 20 has liquid and suction connections 70 and 80 to enable refrigerant, such as liquid ammonia, to be supplied to and evacuated from the refrigerant chamber 23 between the upper and lower plate members 21, 22 of each .freezer plate 20. The liquid connections 70 are connected via individual isolating valves 72 to a vertical liquid header pipe 74 which is, in turn, connected by hoses 76 to a vertical refrigerant supply pipe 78. The suction connections 80 are connected by isolating valves 82 to a suction header pipe 84 which is connected by hoses 86 to a refrigeration compressor via header 88. The liquid and suction header pipes 74 and 84 are fixed to respective corners of the lower plate frame 40 and 20 extend vertically upwards through the sleeves 75 and 85 provided on the upper plate frame 42. At the opposite corners of the plate freezer, false header elements 77 and 87 are secured to the lower plate frame 40 and extend vertically upwards through sleeve members 79, 89 provided on the upper plate frame 42. Safety flanges 73, 83 are provided on the upper end of the header pipes 74, 77, 84, 87 which are adapted to engage with the upper end of the sleeve members 75, 79, 85, 89 to prevent rupture of the hoses in the event of over extension.

A clamping assembly 90 is provided at each side of the plate freezer 10 for clamping the freezing plates 20 when the freezing stations of the stack are fully loaded and the plate stack supported on the lower plate frame is in its lower most position as illustrated in Figures 2, 4 and 6. Each clamping assembly 90 comprises JRG:JA:#25225.CAP 13 July 1998 -9a pivotal clamping arm 94 and a clamping ram 92 for urging the clamping arm 94 into engagement with a side part 43 of the upper plate frame assembly 42 to exert downward pressure thereon. Each clamping ram 92 comprises a hydraulic cylinder the upper end of which is connected to a respective one of the fixed horizontal beams 56, 57, and a piston 96 telescopically moveable within the hydraulic cylinder and with its lower end connected to a free end of the clamping arm 94 which is engageable with the side part 43 of the upper plate frame 42. The other end of the clamping arm 94 is pivotally connected to a fixed horizontal member 98 secured to and extending between the column frame members 34 at the sides of the plate freezer 10. The fixed horizontal members 98 are provided at a level a short distance "above the level of the infeed and outfeed conveyors 12 and 14 and the loading/unloading assembly 16.

o A plate latching assembly 100 is provided at each side of the plate freezer enable the plate freezing stations 28 to be opened sequentially one after another for unloading/loading. Each plate latching assembly 100 comprises a latch member 102 mounted on a respective one of the fixed horizontal members 98 for horizontal movement relative thereto and latch actuator 104 for moving the latch member 102 between a retracted position and an extended position in which the latch member 102 extends into the support frame structure 30. In the extended position, the latch 20 member 102 is engageable with the upper flange 25 of one of the spacers 24 of the plate stack to support the freezing plate 20 on which that spacer is provided.

In use, the sequence of events for automatic operation of the plate freezer will now be described.

Starting with a plate freezer full of frozen cartons from the previous day, the plate stack supported on the lower plate frame 40 is in its lower-most position illustrated in Figure 2, 4 and 6. The loading/unloading assembly 16 is located in front of the plate freezer to be unloaded/loaded. The clamping assembly 90 is released by contracting the hydraulic clamping ram 94. The plate stack supported on the lower plate frame 40 is raised by the lifting ram assembly 60 and chain and pulley arrangement to the top position illustrated in Figures 1, 3 and 5. Each plate JRG:JA:#25225.CAP 13 July 1998 latching assembly 100 is then actuated to extend the latch members 102 into engagement beneath the upper flanges 25 of the spacers 24 fixed to the second bottom freezing plate 20'. The lower plate frame 40 is then lowered to open the bottom freezing station 28'. The loading/unloading assembly 16 is then actuated to extend the pusher head 66 into the bottom freezing station 28 to push one row of frozen cartons onto the outfeed conveyor 14. The outfeed conveyor then starts and removes the row of cartons before stopping again. The process of indexing the pusher across row by row is repeated until the station is cleared. The pusher head 66 is then retracted. Eight fresh cartons are moved by the infeed conveyor assembly 12 into a position in front of the pusher head 66. The loading/unloading assembly is the actuated again to push the row of fresh cartons into the bottom freezing station, and this process is repeated until the station is full of fresh cartons and the pusher is then retracted. The lower plate frame 40 is then raised to close the bottom "'•freezing station 28' and to remove the load from the latch members 102. The latch members are retracted and the plate stack is indexed down by one freezing station before the latch members 102 are advanced to engage the upper flanges 25 of the spacer 24 attached to the third bottom freezer plate. The lower plate frame 40 is then lowered again to open the second bottom freezing station for unloading and loading, and this process is repeated until all of the freezing stations 28 have been 20 unloaded and loaded with fresh cartons. The plate stack supported on the lower plate frame 40 is then moved to its lower-most position of Figures 2, 4 and 6 and the clamping assembly 90 is actuated by extending the clamping ram 92 to move the pivotal clamping arm 94 into engagement with the upper plate frame 42 to provide load on the top plate In the unloading/loading process described above, it will be appreciated that only one freezing station at a time is opened for unloading/loading, and all of the other freezing stations are closed to maintain double-sided freezing contacts on the cartons in the freezing stations. This results in an increase in the time for which the products experience double-sided contacts in the daily freezing cycle, thereby increasing freezing efficiencies and reducing freezing times.

JRG:JA:#25225.CAP 13 July 1998 11 It will also be appreciated that various modifications may be made to the specific embodiments described above without departing from the scope and spirit of the present invention. For instance, a different type of loading/unloading assembly may be used instead of the expandable scissors mechanism for advancing and retracting the pusher head, and a different type of clamping assembly instead of the hydraulic clamping ram arrangement may be used.

C

*ooo JRG:JA:#25225.CAP 13 July 1998

Claims (24)

1. An automatic plate freezer including a stack of horizontally extending freezing plates defining therebetween a plurality of freezing stations, means for raising and lowering the stack of freezing plates relative to a support frame, loading means provided at a level fixed relative to the support frame for loading products into the freezing stations, unloading means provided at the same level fixed relative to the support frame for unloading products from the freezing stations, and latching means operable to support one or more freezing plates above the level of the loading means and unloading means, wherein the freezing plates stack is supported on a lower plate frame which occupies a top position at the start of a loading/unloading process, the lower plate frame being lowered from the top position sequentially through a number of intermediate positions during the loading/unloading process to a bottom position for freezing, the latching means being operated at each intermediate position to support a plate or plates above the bottom plate, the lower plate frame and plate or plates supported thereon below the latching means being lowered in each intermediate position when the latching means is operated to open the freezing station below the plate supported by the latching means with all the other freezing stations being closed. 20 2. An automatic plate freezer according to claim 1 wherein lifting of the lower plate frame to close a freezing station removes the load from the latching means so that it can be released.

3. An automatic plate freezer according to claim 2 wherein the latching means is re-engageable to support another freezing plate when the stack of freezing plates has been indexed down to another freezing station.

4. An automatic plate freezer according to any one of the preceding claims including clamping means to apply pressure to the stack of freezing plates in the Q bottom position for freezing. -13- An automatic plate freezer according to claim 4 wherein the clamping means includes a clamping assembly having a pivotal clamping arm and a clamping ram for urging the clamping arm into engagement with a side part of the uppermost freezing plate.

6. An automatic plate freezer according to claim 4 or claim 5 wherein clamping assemblies are provided on opposite sides of the stack.

7. An automatic plate freezer according to any one of the preceding claims wherein the means for raising and lowering the stack of freezing plates comprises a lifting ram operatively connected to the lower plate frame.

8. An automatic plate freezer according to claim 7 wherein the lifting ram is operatively connected to the lower plate frame via a series of belts or chains of the like S 15 extending around pulleys such that extension of the lifting ram results in a lowering of the lower plate frame and contraction of the lifting ram raises the lower plate frame.

9. An automatic plate freezer according to claim 8 wherein the lower plate frame is connected to a connecting element by lifting belts or chains extending around upper 20 pulleys, the connecting element being connected to a fixed part of the support frame by further belts or chains extending around further pulleys mounted on a movable platform and connected to the lifting ram. An automatic plate freezer according to any one of the preceding claims wherein the freezing plates are separated by spacers fixed to and extending upwardly from the plates.

11. An automatic plate freezer according to claim 10 wherein the latching means has a latching part engageable with a generally horizontally extending upper part of a spacer during the unloading/loading process. -14-

12. An automatic plate freezer according to claim 10 or claim 11 wherein a latching device is provided at each side of the stack of freezing plates, each latching device having a latching part engageable with a respective spacer.

13. An automatic plate freezer according to any one of claims 10 to 12 wherein each spacer is generally C-shaped in cross-section having upper and lower flanges extending substantially horizontally and outwardly from a substantially vertical member.

14. An automatic plate freezer according to claim 13 wherein the lower flange of a spacer is fixed to an upper plate member of a freezing plate below the spacer, and the upper flange provides a support for a freezing plate above the spacer.

15. An automatic plate freezer according to any one of the preceding claims wherein the latching means includes a latch member movable by a latch actuator in a generally horizontal direction between a retracted position and an extended position in which the latch member extends into the support frame. *o

16. An automatic plate freezer according to claim 15 as appended to claim 14 20 wherein the latch member is engageable with the upper flange of a spacer to support the freezing plate to which the lower flange of said spacer is fixed. o

17. An automatic plate freezer according to any one of the preceding claims wherein a single pushing device constitutes the unloading means and loading means, the pushing device including a pusher head that is movable horizontally from a retracted position outside the plate freezer stack into an extended position in an opened freezing station.

18. An automatic plate freezer according to claim 17 wherein the single pushing 30 device includes an expandable scissor assembly.

19. An automatic plate freezer according to any one of the preceding claims wherein the number of freezing stations falls substantially within the range from 10 to

20. An automatic plate freezer according to any one of the preceding claims wherein an infeed conveyor is provided at the front of the plate freezer for supplying fresh products to the loading means, and an outfeed conveyor is provided at the rear of the plate freezer for receiving frozen products unloaded from the freezing stations.

21. An automatic plate freezing installation comprising a plurality of automatic plate freezers in accordance with any one of the preceding claims disposed next to one another with a common infeed conveyor disposed along one side of the plate freezers and a common outfeed conveyor disposed along the opposite side of the plate freezers.

22. An automatic plate freezing installation according to claim 21 wherein a mobile loading/unloading assembly is provided which is movable along the infeed conveyor in a sideways direction from a position in front of one plate freezer to a position in front of another plate freezer.

23. A method of operating an automatic plate freezer having a stack of horizontally extending freezing plates defining therebetween a plurality of freezing stations, said method including the steps of: raising the stack of freezing plates from a bottom position to a top position within a fixed support frame; operating latching means to support all of the freezing plates except the bottom plate; lowering the bottom plate so that the bottom freezing station is opened at a level for unloading/loading which is fixed relative to the support frame; unloading a product from and/or loading a product in the bottom freezing station; raising the bottom plate to close the bottom freezing station and to remove the load from the latching means; releasing the latching means; STand sequentially repeating the steps above for all other freezing stations that are required to be unloaded/loaded; wherein each time a freezing station is opened for -16- unloading/loading, all of the other freezing stations are closed.

24. A method according to claim 23 wherein the stack of freezing plates is supported on a lower plate frame which is raised and lowered relative to the support frame during loading and unloading. A method according to claim 23 or claim 24 wherein pressure is applied to the stack of freezing plates when the stack is loaded and in its bottom position.

26. A method according to any one of claims 23 to 25 wherein the freezing plates are separated by spacers fixed to and extending upwardly from the plates, and the :latching means has a latching part engageable with a generally horizontal extending upper part of a spacer during the unloading/loading process. 15 27. A method according to any one of claims 23 to 26 wherein the step of unloading a product from a freezing station includes pushing the product from the station on an outfeed conveyor.

28. A method according to any one of claims 23 to 27 wherein the step of loading 20 a product into a freezing station includes pushing the product from an infeed conveyor into the freezing station.

29. An automatic plate freezer substantially as hereinbefore described with reference to the accompanying drawings. A method of operating an automatic plate freezer substantially as described herein. Dated 5 September 2001 Freehills Carter Smith Beadle Patent Attorneys for the Applicant 1 P GORDON BROTHERS INDUSTRIES PTY LTD