AU751654B2 - Plate freezing apparatus - Google Patents

Description

I 1I P/00/0011I Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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S S Namne of Applicant: Actual Inventor: Address for service in Australia: Gordon Brothers Industries Pty Ltd John Richard MOTT CARTER SMIT BEADLE 2 Railway Parade Camnberwell Victoria 3124 Australia Invention Title: PLATE FREEZING Details of Associated Provisional Application: PP6349 filed 6 October 1998 APPA tATus IP Austrafia Documents received on: 0 -6 OCT 1999 Batch

NO:

The following statement is a full description of this invention, including the best method of performing it known to us -2- PLATE FREEZING APPARATUS This invention relates to plate freezing apparatus, and to a loading and 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 15 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 maximize Sthe amount of time the products are in contact with plates above and below.

Another disadvantage of a plate freezer having a stack of horizontally extending freezing plate vertically movable relative to a support frame, and loading and unloading means at a level fixed relative to the support frame, is that such a plate freezer requires gantries for supporting the loading and unloading means at or towards the upper end of the support frame and a building of a certain height to accommodate the relatively large amount of vertical movement of the plate stack between its lowermost position and an upper position in which the lowest freezing station is at the level of the loading and unloading means. In many instances, particularly in buildings where the height available is limited, it is desirable to provide a plate freezer which is able to be accommodated in a smaller vertical space. It is also desirable in some circumstances to avoid the use of gantries for supporting the loading and unloading means above the ground.

According to one aspect of the invention, there is provided a plate freezer IRG:JA28773.CAP 6 October 1999 -3including a support frame containing a stack of horizontally extending freezer plates defining therebetween a plurality of freezing stations, opening means for selectively opening each of the freezing stations wherein the opening means is arranged to open the freezing stations at different levels, and only one freezing station is opened with all of the other freezing stations being closed, and loading and unloading means for loading and unloading products from an opened freezing station, wherein the loading and unloading means are movable vertically relative to the support frame.

According to another aspect of the invention, there is provided a method of operating a plate freezer having a support frame containing a plurality of horizontally extending freezer plates defining freezing stations between adjacent plates, the method including: selectively opening the freezing stations for unloading and loading wherein each freezing station is opened at a different level relative to the support frame and only one freezing station is opened at any one time with all the other freezing stations 15 being closed; unloading frozen products from an opened freezing station and raising or lowering the unloaded frozen products to a discharge level; and raising or lowering products to be frozen to the level of the freezing station to be loaded, loading the opened freezing station, and closing the loaded freezing station.

20 The next freezing station can then be opened and unloaded and subsequently loaded in the manner described above.

The loading and unloading means preferably includes infeed elevator means adapted to move products to be frozen from the infeed level to the level of the opened freezing station and outfeed elevator means adapted to move frozen products from the level of an opened freezing station to the discharge level. The loading and unloading means may also include pusher means for pushing products to be frozen from the infeed elevator means into an opened freezing station and/or for pushing frozen products from an opened freezing station onto the outfeed elevator means.

Preferably, a single pusher assembly is provided for both loading and unloading, although it is possible that separate pushers may be provided. In one IRG:1A28773.CAP 6 October 1999 -4preferred embodiment the or each pusher assembly is vertically movable relative to the support frame independently of the infeed and outfeed elevator means, although the pusher assembly or assemblies may be moved simultaneously with the elevators.

Preferably, an infeed conveyor is provided to supply products to be frozen to the freezing stations and an outfeed conveyor is provided to convey frozen products away from the freezing stations of the plate freezer.

In one embodiment, the infeed and outfeed conveyors are provided at a level or levels fixed relative to the support frame with separate vertically movable elevators to move the products to and from the levels of the opened freezing stations. Whilst they may be provided at any desired level, e.g. at the upper end of the support frame, the infeed and outfeed conveyors may be conveniently located at a level at or towards the lower end of the support frame, i.e. just above ground level.

In an alternative embodiment, the infeed and/or outfeed conveyors may be vertically movable relative to the support frame so as to constitute the infeed and/or S 15 outfeed elevator means.

The opening means for selectively opening each of the freezing stations preferably comprises plate lifting means for lifting one or more of the freezer plates.

The plate lifting means is preferably arranged to lift an upper freezer plate of the freezing station to be loaded/unloaded and all other freezer plates above so that only the freezing station to be loaded/unloaded is opened.

In one preferred embodiment, the plate lifting means includes a plurality of lifting jacks mounted on carrier members which are vertically movable relative to the support frame of the plate freezer stack, each lifting jack being engageable with a part a freezer plate to lift that plate and any plates above. When the separation of the freezer plates is less than the height of the liffing jacks, a first set of lifting jacks may be provided for engaging the upper freezer plates of odd numbered freezing stations, and a second set of lifting jacks may be provided for engaging the upper plates of even numbered freezing stations. The lifting means may also include self-centering adjustment devices which enable the orientation of the lifting jacks to be adjusted to compensate for non-alignment of the carrier members for the lifting jacks.

JRG:JA28773.CAP 6 October 1999 A preferred embodiment of the 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; Figure 2 is a plan view of the automatic plate freezer of Figure 1; Figure 3 is an enlarged plan view of plate lifting apparatus of the plate freezer of Figures 1 and 2; Figure 4 is an enlarged end view of part of the plate lifting apparatus of Figure 3; Figure 5 is a perspective view of a lifting jack assembly of the plate lifting apparatus of Figure 3; and Figure 6 is a part sectional view through the lifting jack assembly of Figure The automatic plate freezer 1 shown in the drawings has a support frame containing a stack of substantially horizontal freezer plates 20 defining a plurality of freezing stations, an infeed conveyor 30 passing along the front of the plate freezer stack, an outfeed conveyor 35 passing along the rear of the plate freezer stack, plate station opening means in the form of lifting apparatus 50 adapted to lift one or more of the freezer plates 20 to open a freezing station, an infeed elevator 60 for raising 20 products to be frozen from the infeed conveyor 35 to the opened freezing station, an outfeed elevator 70 for receiving frozen products from an opened freezing station, and a loading and unloading apparatus 40 for loading and unloading an opened plate freezing station 3 with products.

The support frame 10 for the plate freezer stack 2 has a substantially horizontal, rectangular base frame assembly 12, four column frame members 14 extending substantially vertically from the corners of the base frame assembly 12, and a substantially horizontal rectangular top frame assembly 16 mounted on the upper end of the column frame members 14.

As illustrated by Figure 3, each freezer 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 JR&.JA28773.CAP 60ctober 1999 -6so as to define a chamber 23 for receiving a refrigerant fluid such as liquid ammonia.

A spacer 24 is fitted to each side of each freezer plate 20. Each spacer 24 is generally C-shaped in cross-section having upper and lower flanges 25, 26 extending substantially horizontally and outwardly from a substantially vertical member 27. The lower flange 26 is fixed to the upper surface of a horizontally extending side extension 28 of a freezing plate 20 below the spacer 24, and the upper flange 25 is engageable with a cushioning element 29, e.g. of rubber, secured to the lower surface of the extension 28 to provide support for a freezing plate above. The spaces between adjacent freezer plates 20 above and below the spacers form the freezing stations 3 for receiving the products to be frozen which are conveniently contained in cartons having a height corresponding to the height of the spacers 24.

The bottom freezer plate 20' of the plate freezer stack is fixed relative to the base frame assembly 12. One or more of the freezer plates 20 above the bottom freezer plate are adapted to be raised and lowered by the lifting apparatus 50 which S 15 will now be described in greater detail with reference to Figures 3 to 6.

"The lifting apparatus 50 comprises a plurality of lifting jacks 51a, 5 lb provided on lifting beams 52 at each side of the plate freezer stack. The lifting beams 52 are movable substantially vertically relative to the support frame 10. For this purpose, end mounting portions 152 of the lifting beams 52 are connected to four endless 20 lifting chains 53, one at each comer of the support frame 10. Each lifting chain 53 extends around lower and upper sprockets 54 and 55. The lower sprockets 54 are "mounted on a drive shaft 56 which is joumrnalled for rotation in bearings 57 mounted to the lower ends of the column frame members 14. The upper sprockets 55 are mounted on idler shafts 58 joumalled for rotation in bearings 59 mounted on the upper ends of the column frame members 14.

Each lifting jack 5 la, 51 b preferably comprises a hydraulic piston and cylinder assembly 80 having a piston rod 81 which is movable substantially vertically in the cylinder 82, the upper end of the piston rod 81 being engageable with the cushioning element 29 on the side extension 28 of a freezer plate 20 to lift that freezing plate and all other freezing plates above so as to open the freezing station below the freezer JR&JA28773.CAP 6 October 1999 -7plate engaged by the piston rod 81.

Whilst it is possible for four individual lifting jacks to be provided, one at each corner of the plate freezer stack, in the arrangement shown in Figures 1 to 4 of the drawings a pair of lifting jacks 51a and 51 b are provided at each corner of the plate stack. This is because the height of the lifting jacks 51a, 51b is greater than the spacing of the freezer plates 20, and so one set of lifting jacks 51a is provided for lifting even numbered plates, e.g. the 2nd, 4th, 6th etc., of the plate stack and the other set of lifting jacks 5 lb is provided for lifting odd numbered plates, e.g. the 3rd, 7th etc., of the plate stack. Thus, as shown in Figures 1 and 4 the level of the lifting jacks 51a and 51b is staggered. The lower lifting jacks 51a are mounted on channelshaped carrier members 90a provided on the end of horizontally extending piston and cylinder assemblies 91a carried by brackets 92a attached to the lower surfaces of the lifting beams 52. The upper lifting jacks 51b are mounted on channel-shaped carrier members 90b provided on the end of horizontally extending piston and cylinder assemblies 91b carried by brackets 92b attached to the upper surfaces of the lifting beams 52. When it is desired to lift even numbered freezer plates, the piston and "'':cylinder assemblies 91a are extended and the piston and cylinder assemblies 91b are retracted, and when it is desired to lift odd numbered freezer plates, the piston and cylinder assemblies 91b are extended and the piston and cylinder assemblies 91a are retracted.

In operation of the lifting apparatus, the carrier members 90a, 90b for the lifting jacks 51a or 51b may not be exactly horizontal. Referring to Figures 4 to 6, this problem may be overcome by the provision of spring-loaded self-centering adjustment devices 100 for the lifting jacks on either side of the piston and cylinder assemblies 80 of the lifting jacks 51a, 51b. As shown in Figure 6, each self-centering device 100 comprises a piston 101 movable in a cylindrical barrel 102. A lower end of the piston 101 is engageable with a compression spring 103 located in the barrel 102. A screw-threaded adjustment member 104 extends through an opening in a top cap 105 of the barrel 102 enabling the vertical location of the piston 101 in the barrel 102 to be adjusted. The pistons 101 are connected by horizontally extending IRG:JA28773.CAP 6 October 1999 -8attachment members 106 to opposite sides of the cylinder 82 of a respective lifting jack 51a, 51b, and the barrels 102 are connected to a respective carrier member by mounting members 107 extending substantially horizontally and perpendicularly to the attachment members 106. The self-centering adjustment devices 100 thus enable the orientation of the lifting jacks 51a, 51b to be adjusted to compensate for non-alignment of the carrier members 90a, The infeed and outfeed conveyors and elevators 30, 35, 60 and 70 will now be described in greater detail.

The infeed conveyor 30 comprises a series of horizontally extending rollers 31 rotatably mounted on a conveyor or stand 32 which is fixed to the floor of the building where the plate freezer is installed. When two or more plate freezers 1 are installed side-by-side, the conveyor 30 preferably extends alongside the front of all of the plate freezers.

The infeed elevator 60 has an elevator platform 61 disposed between the infeed conveyor 30 and the front of the plate freezer stack 2. The elevator platform 61 is able to be raised and lowered relative to the infeed conveyor 30 and the support frame by a lifting chain arrangement 62. Four lifting chains 63 are provided in the lifting chain arrangement 62. One end of each lifting chain 63 is connected to the elevator platform 61, and the lifting chain 63 extends downwardly from the elevator platform 61, around a lower sprocket 64, upwardly to an upper sprocket 65, around the upper sprocket 65 and then downwardly to an elevator counterweight 66 to which the other end of the lifting chain 63 is attached. The lower sprockets 64 are mounted on a rotatable shaft 67 connected by a drive coupling 68 to an infeed elevator drive unit 69 which is operable to raise or lower the elevator platform 61.

The outfeed conveyor 35 also comprises a series of horizontally extending rollers 36 rotatably mounted on a conveyor stand 37 which is fixed to the floor of the building where the plate freezer 1 is installed. When two or more plate freezers are installed side-by-side, the outfeed conveyor 35 preferably extends alongside the rear of all the plate freezers.

The outfeed elevator 70 has an outfeed elevator platform 71 disposed between JRG:JA28773.CAP 6 October 1999 the outfeed conveyor 35 and the rear of the plate freezer stack 2. The elevator platform 71 is able to be raised and lowered relative to the outfeed conveyor 35 and the support frame 10 by a lifting chain arrangement 72. Four lifting chains 73 are provided in the lifting chain arrangement 72. One end of each lifting chain 73 extends downwardly from the elevator platform 71, around a lower sprocket 74, upwardly to an upper sprocket 75, around the upper sprocket 75 and then downwardly to an outfeed elevator counterweight 76 to which the other end of the lifting chain 73 is attached. The lower sprockets 74 are mounted on a rotatable shaft 77 connected by a drive coupling 78 to an outfeed elevator drive unit 79 which is operable to raise or lower the outfeed elevator platform 71.

The loading and unloading apparatus 40 for loading and unloading the plate freezing stations 3 comprises a pusher device 41 for pushing cartons of the product to be frozen from the infeed elevator platform 61 into an opened freezing station 3 and for pushing frozen cartons out of the opened freezing station 3 onto the outfeed elevator platform 71. As shown in Figure 2, the pusher device 41 is in the form of a hydraulically operable scissor mechanism 140 carried on a pusher frame 141 and having a pusher head 142, but it will be appreciated that other types of pusher devices may be used in the present invention.

The pusher device 41 mounted on the pusher frame 141 is able to be raised and S 20 lowered relative to the support frame 10 by a lifting chain arrangement 42. Four lifting chains 43 are provided in the lifting chain arrangement. One end of each lifting chain 43 is connected to the pusher frame 141 and the lifting chain 43 extends downwardly from the pusher frame 141, around a lower drive sprocket 44, upwardly "to an upper idler sprocket 45 mounted on an idler shaft 145, around the upper sprocket 45 and then downwardly to a pusher frame counterweight 46 to which the other end of the lifting chain 43 is attached. The lower sprockets 44 are mounted on a rotatable drive shaft 47 connected by a drive coupling 48 to a pusher frame drive unit 49 which is operable to raise or lower the pusher frame 141.

The operation of the automatic plate freezer will now be described in relation to the unloading and loading of a fully loaded plate freezer with all of the freezing IRG:JA28773.CAP 6 October 1999 stations loaded with cartons of freezer products. The plate lifting apparatus 50 is operated to open the freezing station 3" above the freezing station 43 to be opened, so as to lift that plate 20" and all plates 20 above. Thus, all the other freezing stations 3 remain closed except the actual freezing station being opened. This has the advantage of maximizing the amount of time the products are in contact with the freezer plates in the other freezing stations.

The pusher frame 141 of the loading and unloading apparatus 40 is moved up to the level of the opened freezing station 3" by operating the pusher frame drive units 49. The outfeed elevator platform 71 is also moved up to the level of the opened freezing station 3" by operating the outfeed elevator drive units 79 and then the pusher device 41 can be operated to push frozen cartons of the product out of the freezing station 3" onto the outfeed elevatorplatform 71. The frozen cartons are then lowered by the outfeed elevator 70 to the level of the outfeed conveyor 35 and then pushed from the outfeed elevator platform 71 onto the outfeed conveyor rollers 36 by an outfeed pusher 38.

In order to load an unloaded, opened freezing station cartons of product to be frozen are pushed from the infeed conveyor 40 onto the infeed elevator platform 61. The infeed elevator apparatus 60 is then operated to move the infeed elevator platform 61 up to the level of the opened freezing station 3" and cartons of the product to be frozen can then be pushed by the pusher device 41 from the infeed elevator platform 61 into the opened freezing station When the freezing station 3" has been filled with cartons, the plate lifting apparatus 50 is operated to contract the piston and cylinder assembly 80 of the lifting jacks 5 la or 51b to close the freezing station 3".

The process can then be repeated for all other freezing stations 3 which are required to be unloaded/loaded.

The plate freezer described above differs from conventional horizontal plate freezers which have an infeed/outfeed level fixed relative to the support frame for the plate freezer stack. Such conventional plate freezers require a greater building height to accommodate substantial vertical movement of the plate freezer stack which is required to move a freezing station to be loaded/unloaded to the infeed/outfeed level.

JG.IJA28773.CAP 60ctoba 1999 -11- The plate freezer of the present invention which has infeed/outfeed elevators and loading and unloading apparatus movable relative to the support frame of the plate freezer stack can thus be accommodated in a building of lesser height than a conventional horizontal plate freezer. Also, in the plate freezer described above, only one freezing station is opened for unloading and loading at any time, thereby maximizing the amount of time the other freezing stations are closed.

It will be appreciated that various modifications and alterations may be made to the preferred embodiment described above, without departing from the scope and spirit of the present invention. For instance, the plate freezer may include clamping means (not shown) to exert additional pressure on the freezer plates of the plate freezer stack when all the freezing stations 3 have been unloaded and loaded with fresh products.

In another, modified embodiment of the invention (not shown), the fixed infeed and outfeed conveyor rollers 31, 36 and the elevator platforms 61 and 71 may be replaced by combined infeed and outfeed elevating conveyors which are movable vertically to raise and lower the products to the levels of the opened freezing stations.

The infeed and discharge levels of the elevating conveyors are preferably at an intermediate position of the plate freezer stack with the conveyors being raised or lowered to the freezing station which is opened for unloading and loading. It will, S 20 however, be appreciated that the infeed and discharge levels at which products are conveyed to and away from the plate freezer may be varied. Such a modified embodiment would be more compact and possibly more economical than the embodiment of Figures 1 to 6.

JRG:JA28773.CAP 10.-10 !9991

Claims (19)

12- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A plate freezer comprising a support frame including a stack of horizontally extending freezer plates defining therebetween a plurality of freezing stations, opening means for selectively opening each of the freezing stations, the opening means being arranged to open the freezing stations at different levels with only one freezing station being opened with all of the other freezing stations being closed, and loading and unloading means for loading and unloading products into or from an opened freezing station, wherein the loading and unloading means are movable vertically relative to the support frame. 2. A plate freezer according to claim 1 wherein the loading and unloading means include infeed elevator means adapted to raise or lower products to be frozen to the level of an opened freezing station and outfeed elevator means adapted to raise or lower frozen products from the level of the opened freezing station to a discharge level. 3. A plate freezer according to claim 1 or claim 2 wherein the loading and unloading means include a pusher assembly for pushing products to be frozen from 20 the infeed elevator means into an opened freezing station. 4. A plate freezer according to claim 2 or claim 3 wherein the loading and unloading means include a pusher assembly for pushing frozen products from an "opened freezing station onto the outfeed elevator means. A plate freezer according to any one of claims 2 to 4 wherein a single pusher assembly is provided for both loading and unloading products into and from the feeding stations. 6. A plate freezer according to any one of claims 3 to 5 wherein the or each .RG:JA28773.CAP 6 October 1999 -13- pusher assembly is vertically movable relative to the support frame independently of the infeed and outfeed elevator means. 7. A plate freezer according to any one of claims 3 to 5 wherein the or each pusher assembly is vertically movable relative to the support frame simultaneously with the infeed and outfeed elevator means. 8. A plate freezer according to any one of claims 3 to 7 wherein the or each pusher assembly comprises a pusher head which is movable in a substantially horizontal direction by a hydraulically operable scissor mechanism. 9. A plate freezer according to any one of the preceding claims wherein an infeed conveyor is provided to supply products to be frozen to the freezing stations, and an .outfeed conveyor is provided to convey frozen products away from the freezing 15 stations of the plate freezer. A plate freezer according to claim 8 wherein the infeed and outfeed conveyors are provided at a level or levels fixed relative to the support frame and separate vertically movable elevators are provided to move the products to and from the levels 20 of opened freezing stations. 11. A plate freezer according to claim 8 wherein the infeed and/or outfeed conveyor is vertically movable relative to the support frame so as to constitute the infeed and/or outfeed elevator means. 12. A plate freezer according to any one of the preceding claims wherein the loading and unloading means are adapted to be raised and lowered by an arrangement of lifting chains.

13. A plate freezer according to any one of the preceding claims wherein the JRG:JA28773.CAP 6 October 1999 I.

14- opening means for selectively opening the freezing stations comprises plate lifting means for lifting one or more of the freezer plates. 14. A plate freezer according to claim 13 wherein the plate lifting means is arranged to lift an upper freezer plate of a freezing station to be loaded/unloaded and all other freezer plates above so that only the freezing station to be loaded/unloaded is opened. A plate freezer according to claim 13 or claim 14 wherein the plate lifting means includes a plurality of lifting jacks mounted on carrier members which are vertically movable relative to the support frame.

16. A plate freezer according to claim 15 wherein a first set of lifting jacks is provided for engaging the freezer plates of odd numbered freezing stations, and a second set of lifting jacks is provided for engaging the freezer plates of even numbered freezing stations.

17. A plate freezer according to claim 15 or claim 16 wherein the carrier members comprise lifting beams which are adapted to be raised and lowered by an arrangement 20 of lifting chains.

18. A plate freezer according to any one of claims 15 to 17 wherein each lifting jack comprises a hydraulic piston and cylinder assembly including a piston rod engageable with a part of a freezer plate to lift that freezer plate and all other freezer plates above so as to open the freezing station below the freezer plate engaged by the piston rod.

19. A plate freezer according to claim 18 wherein cushioning elements are provided on side extensions of the lifting plates, the cushioning elements being engageable by the piston rods of the lifting jacks. JRG.JA28773.CAPO 6 October 1999 A plate freezer according to any one of claims 15 to 19 wherein the lifting jacks include self-centering adjustment devices for adjusting the orientation of the lifting jacks relative to the carrier members.

21. A plate freezer according to claim 20 wherein the self-centering adjustment device for each lifting jack comprises a pair of spring-loaded pistons movable in cylindrical barrels, the spring-loaded pistons being connected to opposite sides of the lifting jack and the barrels being connected to a carrier member for the lifting jack.

22. A plate freezer according to claim 21 wherein screw-threaded adjustment members are engageable with the pistons of the adjustment device to enable the vertical locations of the pistons within the barrels to be adjusted. 15 23. A method of operating a plate freezer having a support frame containing a plurality of horizontally extending freezer plates defining freezing stations between adjacent plates, the method including: selectively opening the freezing stations for unloading and loading wherein each freezing station is opened at a different level relative to the support frame and 20 only one freezing station is opened at any one time with all the other freezing stations being closed; unloading frozen products from an opened freezing station and raising or lowering the unloaded frozen products to a discharge level; raising or lowering products to be frozen to the level of the freezing station to be loaded; loading the opened freezing station; and closing the loaded freezing station.

24. A method according to claim 23 wherein the steps of unloading and loading the freezing stations include pushing frozen products from each opened freezing rJA2873.CAP 6 October 1999 -16- station onto an outfeed elevator means and pushing products to be frozen from an infeed elevator means into each opened freezing station. A method according to claim 23 or claim 24 further comprising: conveying products to be frozen to the plate freezer and raising or lowering said products to the levels of each opened freezing station, raising or lowering frozen products unloaded from each opened freezing station and conveying the frozen products away from the plate freezer.

26. A method according to claim 25 wherein the products are conveyed to and from the plate freezer by conveyors at a level or levels fixed relative to the support frame and the products are raised or lowered to and from the levels of each opened freezing station by separate elevators.

27. A method according to claim 25 wherein the products are conveyed to and from the opened freezing stations by conveyors which are vertically movable relative to the support frame of the plate freezer.

28. A method according to any one of claims 23 to 26 wherein each freezing 20 station is opened by lifting one or more of the freezer plates.

29. A method according to claim 28 wherein each freezing station is opened by oooo, lifting the upper freezer plate of that station and all the freezer plates above so that only the freezing station to be loaded/unloaded is opened. A method according to claim 29 wherein the freezer plates are lifted by lifting jacks engageable with parts of the freezer plates.

31. A method according to claim 30 wherein a plurality of sets of lifting jacks are provided, the jacks of a first set being engageable with plates of odd numbered JRG:JA28773.CAP 6 Octobr 1999 -17- freezing stations, and jacks of a second set being engageable with plates of even numbered freezing stations.

32. A method according to claim 30 or claim 31 wherein the lifting jacks are mounted on carrier members which are vertically movable relative to the support frame.

33. A method according to claim 32 wherein the lifting jacks include self-centering adjustment devices for adjusting the orientation of the lifting jacks to compensate for non-alignment of the carrier members.

34. A plate freezer substantially as hereinbefore described with reference to the accompanying drawings.

35. A method of operating a plate freezer substantially as described herein. DATED: 6 October, 1999 0 20 CARTER SMITH BEADLE Patent Attorneys for the Applicant: Gordon Brothers Industries Pty Ltd S. *O S Oe*e IRG:JA28773.CAP 6 October 1999