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PATENTS ACT 1953
COMPLETE SPECIFICATION
AUTOMATIC PLATE FREEZER
We, Gordon Brothers Industries Pty Ltd
An Australian Company of 21 Michael Street Brunswick Victoria 3056 Australia
HEREBY declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly descnbed m and by the following statement
INm^UATpROPERrToFFicE
OF NZ
16 JUL 1998 j -REC Fn/cp /
(c) An automatic plate freezer (10) includes a stack of horizontal freezing plates (20) defining a plurality of freezing stations (28) The plate stack is supported on a lower plate frame (4) which is raised and lowered relative to a support frame structure (30) during a loading/unloading process In the loading/unloading process, the lower plate frame (40) is initially lifted from a bottom position for freezing to a top position in which a latching assembly (100) is operable to support the second bottom plate The lower plate frame (40) and bottom plate (20') are then lowered to open the bottom freezing station (28') for unloading/loading The process continues with each freezing station (28) being unloaded/loaded sequentially in such a manner that only the freezing station that is being unloaded/loaded is opened, with all the other freezing stations being closed so as to maximise the amount of time the products in the plate freezer are in contact with the freezing plates above and below
A
" 10
® 20
This invention relates to an automatic plate freezer, and to a loading/unloading method therefor It particularly relates to automatic plate freezers of the land 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 descnbed above typically include loading means for loadmg the products to be frozen, pressure-applying means for applying pressure to the stack of freezing plates when loaded, and unloading means for removmg the frozen products In conventional plate freezers, the plate freezer stack is progressively opened and closed as it is unloaded and loaded Normally, m such a method of operation, all of the stations above the station being unloaded/loaded are m the open position so that all products m those stations expenence 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
According to one aspect of the present invention, there is provided an automatic plate freezer including a stack of honzontally extending freezing plates defining therebetween a plurality of freezing stations, means for raising and lowenng 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, unloadmg 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 unloadmg 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 dumig the icadmg/unloading process to a bottom position for freezing, the latching means being operated ai «?ach intermediate position to support a
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plate or plates above the bottom plate, the lo^sr plate frame and plate or plates
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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 free
JRGTOC #28851 RSI
® 20
£2^
r
*
The lower plate frame is adapted to be raised and lowered relative to the support frame during the loadmg and unloading process The lower plate frame is adapted to be lifted from the bottom position foi 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 loadmg and unloading means with all of the plate freezing stations above being closed The bottom freezing station can then be unloaded, if it previously contamed 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 to 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 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 m 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 dunng the unloadmg/loadmg process
JRGTOC #28851 RSI
r
According to another aspect of the invention, there is provided a method of unloadmg/loadmg 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 5 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 unloadmg/loadmg which is fixed relative to the support frame, unloading a product from and/or loadmg a product into the bottom freezing station, raising the bottom plate to close the bottom freezing 10 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 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
In a particularly preferred arrangement, the freezing plates are separated by 15 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 cach 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 ccnnectcd 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 25 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
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station or to push fresh products into the freezing station Preferably, the i
unloadmg/loadmg mechanism comprises an expandable scissor assembly
Preferably, an mfeed 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 5 unloaded products pushed out of the freezing stations by the unloadmg mechanism A preferred embodiment of the present invention will now be descnbed, by way of example only, with reference to the accompanying drawings, m 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, 10 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 15 Figure 1,
Figure 6 :s 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 mfeed convcyor 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 30 mounted on the upper end of the column frame members 34
Each freezing plate 20 of the plate freezer stack has an upper plate member 21 and a lower plate member 22 spaced apart oy 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 5 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 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 10 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 Geezer stack is supported on a lower plate frame 40 and the top plate 20" is secured to an upper plate frame 42 The lower 15 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 rcfcrence 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 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 arc 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 t
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 i
freezer The third pulleys 52 are mounted on a platform 58 which is vertically
moveable relative to the support irame 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 5 Operation of the lifting ram assembly 60 to extend the piston rod 62 raises the platform 58 and results m a corresponding lowenng of the lower plate frame 40 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 10 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 f od products to be frozen However, the number of freezing stations will 15 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 mfeed 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 25 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 mfeed conveyor in a 30 sideways direction from a position in front of one plate freezer to a position in front
of another plate freezer Each loading/unloading assembly 16 has a pusher head 66 extendmg 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 5 conveyor 12 into a freezing station 28 or to push frozen cartons from a freezing station 28 onto the outfeed conveyor 14
As descnbed 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 \\ hich the loading/unloading assembly 16 and infeed 10 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 15 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 25 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 30 position as illustrated m Figures 2, 4 and 6 Each clamping assembly 90 composes
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a 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 95, the upper end of which is connected to a respective one of the fixed honzontal 5 beams 56, 57, and a piston 96 telescopically moveable withm the hydraulic cylinder 95 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 pivutally connected to a fixed honzontal member 98 secured to and extending between the column frame members 34 at the sides of the plate 10 freezer 10 The fixed honzontal 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
A plate latching assembly 100 is provided at each side of the plate freezer 10 to enable the plate freezing stations 28 to be opened sequentially one after another 15 for unloading/loading Each plate latching assembly 100 compnses a latch member 102 mounted on a respective one of the fixed honzontal members 98 for honzontal 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 strucUire 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 descnbed
Starting with a plate freezer full of frozen cartons from the previous day, the 25 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 30 pulley arrangement to the top position illustrated in Figures 1, 3 and 5 Each plate
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 15 is then actuated to 5 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 10 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 15 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 20"
In the unloading/loading process descnbed 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 30 increasing freezing efficiencies and reducing freezing times
It will also be appreciated ihat various modifications may be made to the specific embodiments described above without departing from the scope and spmt 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