DEVICE FOR AUTOMATIC UNLOADING OF VERTICAL FREEZERS The present invention regards a device for unloading of vertical freezers, especially freezers for freezing offish and other seafood products, in accordance with the preamble of the appended Claim 1.
This type of freezer is primarily intended for use on board fishing vessels, in particular factory trawlers, and comprises a freezing chamber for freezing fish in half blocks of around 20 kg, alternatively in whole blocks of around 40 kg. After the desired core temperature has been achieved in the blocks, the freezer must be unloaded and the blocks transported to storage on board the ship. Unloading of the freezer is effected by the floor of the freezer being lifted up to make the blocks protrude above the edges of the freezing chamber. Any partitions between the blocks are removed manually, and the blocks are lifted out by hand. The blocks are placed on trolleys or a conveyor belt for further transport.
Even if the most common thing to do is to remove the blocks by hand, there is an automatic unloading system on the market. This operates in a manner such that the blocks, when raised to the uppermost position, are gripped by a large claw. The claw grips all the blocks and presses them together. Then the blocks are lifted onto a table where they are separated and transported further. Several problems are associated with this unloading device. First of all, it requires a lot of space, which on a cramped fishing vessel is a great disadvantage. Moreover, it requires the installation of rail systems on the underside of the deck above and good headroom. The rail systems may also get in the way of the filling belt often mounted above the freezers. This all means that this device is not practicable on board a ship. Another problem is that the squeezing together of the plates may cause these to freeze to each other, thus making it problematic to separate them afterwards. These problems have resulted in a lack of success for this known unloading system.
Thus in NO 149 941, there is described a vertical freezer in which the frozen materials disposed between the freezing plates may be carried upwards to make them freely accessible for removal from the freezer. No specific method is described for removing the freely accessible blocks.
NO 309 957 describes an improvement by a vertical freezer, where the improvement comprises a draft that reduces the risk of interruption due to formation of ice in the freezer. Apart from this, the freezer described in this publication is a conventional vertical freezer in which the freezing plates may be moved relative to each other in order to facilitate loading and unloading.
NO 140 689 describes a vertical freezer in which the freezing plates may be moved apart to allow the frozen materials to be removed by a separate removal mechanism. The removal mechanism described is a hoisting device that hoists a large number of blocks of frozen materials out of the freezer and carries them off for further processing.
NO 119 685 also concerns a vertical freezer. The frozen materials between the freezing plates can be removed by lifting or lowering the freezing plates, whereupon they are pushed out by means of a special push device arranged on the side of the freezer, and then optionally placed on a conveyor belt.
NO 109 835 also describes an unloading device for vertical freezers arranged on the side of the freezer, which may remove frozen materials from this.
The unloading mechanisms described in the above cited publications suffer from the exact same problems as those stated in the general discussion of the state of the art, and they also require a significant amount of manual work.
The manual work is heavy, resource-demanding and associated with a certain amount of risk. Thus there exists a desire to simplify this unloading process and to mechanize it to the greatest possible extent. This is achieved by the characteristics that appear from Claim 1.
Further advantageous characteristics are given in the subsequent dependent claims.
The invention will now be explained in greater detail with reference to the accompanying figures, in which:
Figure 1 is a perspective view of a row of three freezers equipped with an unloading device according to the present invention;
Figure 2 is a sectional view along line A-A through a freezer according to Figure 1;
Figure 3 is a sectional view along line B-B through a freezer according to Figure 1;
Figure 4 is an end view of the freezer;
Figure 5 is a top view of a cutout of the freezer; and
Figure 6 is a side view of a cutout of the freezer.
Figure 1 shows a perspective view of three freezers 1, 2 and 3 placed one after the other in a row. Each freezer comprises two freezing chambers 4 separated by vertical freezing plates 5. Each freezing chamber is divided into two by means of a partition 6. The freezing chambers are used for placing products to be frozen, e.g. fish. Preferably, the fish is delivered via a conveyor belt arranged above the freezer. This is not shown in Figure 1.
When the fish is frozen, it will form frozen blocks 7. In the example shown with partitions 6, the blocks 7 are half blocks, i.e. each block extends only across half the length of the freezing chamber 4. If the partition is removed, whole blocks will form.
Figure 2 shows a section through a freezer along line A-A, and figure 3 shows a section through the freezer along line B-B. The freezer has a frame 8 into which the freezing plates 5 are fitted. Between the freezing plates is arranged a liftable and lowerable floor 9. The floor is connected to a lifting and lowering mechanism. According to the invention, one lifting and lowering mechanism 10 is provided on one side of the
partition 6, and one lifting and lowering mechanism 11 on the other side of the partitions 6. The floors 9a on one side of the partitions 6 are connected to the same lifting and lowering mechanism 10, the lifting and lowering mechanism 10 extending along the entire length of the freezer. Likewise, the floors 9b on the other side of the partitions 6 are connected to the same lifting and lowering mechanism.
Each lifting and lowering mechanism 10 and 11 comprises a lifting bracket 12 provided underneath each floor 9a, 9b, a lifting beam 13 that extends underneath all the lifting brackets 12 and is connected to these and a lifting cylinder 14 at each end of the lifting beam 13. The lifting cylinder 14 acts between the frame 8 and the lifting beam 13. When the lifting cylinder 14 is actuated to contract, the lifting beam 13 and consequently the lifting bracket 12 and the floor 9, will lift.
Each partition 6 is connected to a partition lifter 15, which is a beam extending along the entire length of the freezer. At each end, the partition beam 15 is connected to a cylinder 16, which upon actuation causes the partition beam 15 to be lowered, thus also lowering the partitions 6.
A push arm beam 17 is provided along the freezers 1, 2 and 3, extending along the length of the freezers at one side of these. The push arm beam may be attached to the freezers 1, 2 and 3, or to the freezer foundation. On the opposite side of the freezers there is provided a conveyor belt or conveyor trough 18 that extends along the length of the freezers and on to a block 7 reception area.
A push arm 19 is arranged so as to be able to travel along the push arm beam 17. This may be driven by a motor arranged at the inner end of the push arm 19, a wire draw or in another known manner.
By the outer end of the push arm 19 there is a curved track 20 that curves in the direction of the conveyor belt 18. From the curved track 20, a trough 25 leads down to the conveyor belt 18. Preferably, this trough 25 is supported on the conveyor belt 18 by means of wheels 26 (see Figure 6), sliding blocks or similar.
The push arm and its operation will now be explained in greater detail with reference to Figures 4, 5 and 6. Figure 4 shows an elevation of the push arm 19. Figure 5 is a top view of the push arm, and Figure 6 is a side view of the push arm. One or more pushers 21 are provided along the push arm 19. These are fixed to a continuous push belt 22 that extends across reversing wheels 23 at either end of the arm 19. The belt 22 is preferably operated by means of a motor 27 disposed by one of the reversing wheels 23. One or more chains may also be used instead of belt 22. The pushers 21 move along one side of the arm 19, around one of the reversing wheels 23, back along the other side of the arm and around the other reversing wheel 23. Alternatively, a reciprocating pusher may be provided, attached to e.g. a hydraulic or pneumatic cylinder.
The trough 25 may be hinged to the curved track 20 or be formed as a separate trolley that follows the curved track 20 as the arm 19 moves along the freezer 1.
The operation of the unloading device will now be explained with reference to Figures 1 - 4.
After the fish or other products have been frozen, the refrigeration plates 5 are heated to a temperature that causes the blocks 7 to detach from the freezing plates. When the blocks are loose, the lifting cylinder 14 is actuated so as to lift the floor 9 between the freezing plates 5. At the same time, the cylinders 16 are actuated, lowering the partitions 6. The lifting of the floors 9 and the lowering of the partitions 6 is adjusted so that when the floors 9 are lifted fully and the partitions 6 are lowered fully, the lower edges of the blocks 7 will be over the top of the partitions 6. As an example, the floors may be lifted approximately 30 cm while the partitions are lowered approximately 20 cm, leaving typical 50 cm blocks clear of the partitions.
The side wall of the freezer 1 on the side where the blocks are pushed out is designed to be either lowered or removed, have the upper part hinged down or otherwise allow the blocks to pass.
The push arm 19 is located by the front 24 of the freezer. The push belt 22 is put into operation, and shortly after, one pusher will strike the closest block 7. The block 7 will then be pushed across the freezer 1. This block will in turn push on the adjacent block, pushing this ahead. Both blocks are pushed out of the freezer and towards the curved track 20. The curved track 20 may be equipped with driving rollers that effect the transportation of the blocks down to the conveyor belt 18, but it is also possible for the blocks to slide along it solely through the force of gravity. When the blocks arrive at the conveyor belt, this will transport the blocks to a reception area for packing.
The push arm will then be displaced along the push arm beam 17 to the next blocks in the freezer 1, pushing these out in the same way as before. In this manner, the whole freezer may be unloaded. When the first freezer 1 is empty, the arm 19 is moved along the push arm beam 17 to the next freezer.
On board ships in particular, there may be stays or supports that can get in the way of the push arm. It is therefore expedient to design this in a manner that allows it to be removed from the push arm beam or swivelled up to pass by these obstacles.
When the freezer is empty, the floor 9 may again be lowered to the lower edge of the freezing plates 5, and the partitions 6 lifted to a position in which their tops align with or are located above the partitions. Re-filling of the freezer can then commence.
The present invention has been described with reference to a specific embodiment. In this embodiment, the push arm is arranged to travel along a push arm beam running along one side of the freezer. For reasons of space, it may be appropriate for the push arm to travel along a rail running along one side of the freezer. However, as those skilled in the art will appreciate, the push arm may also run along two beams or rails, one on either side of the freezer. Optionally, this beam or rail, or these beams or rails, may be arranged above the freezer.