DEVICE FOR STACKING TRAYS WITH ARTICLES

Abstract: A device for stacking trays (S) containing eggs comprising a feed conveyor (2) taking the trays one after the other, a discharge conveyor (3) for the trays stacked on each other, a conveyor mechanism (15), operating between the feed and discharge conveyor having up and down carrying means (20) for one tray at a time, and a support (30) taking the stacked trays and always rotating through 90 o . The discharge conveyor (3) extends on each side of the support (30) being movable from a low position to a high position and vice versa. The carrying means (20) are movable along a closed track extending in a vertical plane and are designed as, fork­ shaped or rake-shaped, elements (22) projecting on said plane. The elements (22) can be folded about a horizontally extending axis on a carrier (20) being movable along a track. At least one pair of folding elements, always provided opposite each other in pairs on either side of the feed and discharge conveyor, is provided on a carrier.

Description: The invention relates to a device for stacking trays, comprising a feedconveyor, carrying the trays one after the other and a discharge conveyor for stacks of trays further comprising a transport mechanism with up and down moving carrying members for carrying the trays one by one to a support platform, which platform is provided with means for a down and upward movement as well as for an oscillating movement through a 90° angle around a vertical axis of this support platform. Such a device, mainly for unstacking of trays but also for stacking, is known from US-A 3,792,784. In the known device the trays are displaced side for the bar the transport mechanism in order to be bast from one conveyor to another. During the operation the supple platform must either be raised or lowered stepwards corresponding to the signals of each tray with its content these boast features are not condesive for a smooth and rapid operation. The object of the invention is to provide a device in which both drawbacks are avoided. For this purpose the device according to the invention is characterized in that the movement of the fed conveyor for the separate trays and the movement of the discharge conveyor for the stacks of trays have the same direction and in that the down - and upward movement of the support platform is only activated after reaching the intended stack height of traus upon the platform and prior to the start of the next stacking cycle. Due to these features, the trays will always proceed in one and the same direction which contributes to the good operation of the device. In a favorable embodiment of the device according to the invention, the transport mechanism comprises two endless conveyors, disposed one on the left and one of the right side of the feed conveyor and of the discharge conveyor each of said endless conveyors forks or rakes, carrying forks or rakes each upwardly pivotable, connected with their pivot axis horizontally disposed to the conveyor, which forks and rakes are capable of simultaneously engaging opposite side edges of a tray to transport the tray from the feed conveyor to the support platform. In a further elaboration of the invention the discharge conveyor can comprise two parallel and spaced flights with its horizontal support surface parallel with the topsides of said flights and between the downgoing part of the endless conveyor of the transport mechanism. Further the feed conveyor and the discharge conveyor can comprise a single endless conveyor consisting of two parallel flights passing around a plurality of guide rollers mounted at different height levels such that the discharge conveyor is lying at a different height level compared to the feed conveyor. The above mentioned and other features will be explained in greater detail in the description of the figures further on, with reference to the appendant drawing: Fig. 1 shows a perspective topview of the device according to the invention; Fig. 2 shows a vertical side view of the device of figure 1; Fig. 3 shows a vertical rear view of the drive of the conveyor mechanism; Fig. 4 shows a side view of the mechanism of Fig. 3; Fig. 5 shows a vertical rear view according to the arrow IV in Fig. 4 of the carrying means with folding fork-shaped element according to the invention. In the figures the same parts are shown by the same reference numbers. The device has a frame 1, which is essentially made up of sections combined to form a frame. The lefthand side in Figs. 1 and 2 shows a feed conveyor 2 in the frame, while a discharge conveyor 3 is shown on the righthand side. In the embodiment shown the feed conveyor and discharge conveyor are formed by a common endless belt 4, two of which are provided parallel and next to each other. The belts 4 run in synchronism and are passed round reversing rollers 5 at the beginning of the feed conveyor and at the end of the discharge conveyor respectively, and guide rollers 6 and drive roller 7 respectively, in such a way that the working part of the belt 4 in the feed conveyor is lower down than the working part of the belt in the discharge conveyor. The drive roller 7 is also designed with a pressure roller 8, which increases the turning angle of the belt 4 about the roller 7 and therefore improves the traction thereon. The roller 7 is driven by a drive motor 9, which drives the shaft 10 of the rollers 7 lying in line with each other, either by means of a transmission or directly, in the direction of the arrow P1, as a result of which the belt follows the direction of the arrow P2 in the working top part thereof. The working part of the feed conveyor 2 lies at such a height that it can be adjusted to the discharge height of, for example, the collection machines for the eggs placing same in a tray S. The height of the discharge conveyor 3 is such that it is advantageous for manual work, for example the man who has to pick up the stack of trays S. At the end of the feed conveyor or discharge conveyor there is a fixed stop 11 extending over the full width of the conveyor, and serving to retain a tray S when it is conveyed on the conveyor belts 4. Provision is made between the feed and discharge conveyors 2, 3 for a conveyor mechanism 15, which deposits the trays one by one from the feed conveyor onto the beginning of the discharge conveyor 3, said beginning being left of the high belt part of the conveyor 4. This conveyor mechanism essentially comprises two chains 16 extending on either side of the conveyor belt 4 in a vertical plane. The chain, for example an ordinary link chain, is conveyed round two top chain wheels 17, two bottom chain wheels 18, and a drive chain wheel 19. A carrying means 20 is suspended in a swivelling manner from the chain, in such a way that the swivel axis is at right angles to the plane of movement of the chain, and the carrier 20 can swing to and fro in the plane of drawing of Fig. 2. In the embodiment shown, three carriers are disposed on the chain at equal intervals from each other. The device is such that two carriers 20 are always suspended from the chains 16 precisely opposite each other on either side of the conveyor belts 4. Each carrier has a fork or rake-shaped element, comprising a bar 21 extending in the horizontal direction and having bar-shaped teeth 22 standing perpendicular thereto. The teeth 22 are bent upwards, as can be seen in Fig. 5. The bar 21 is pivoted in the carrier 20, in such a way that the teeth 22 can move upwards in the direction of the arrow P1, and vice versa. The downward movement is prevented by a stop 23, which is fixed to a bracket 24, which forms part of the carrier 20. In this way the element 21, 22 can only move upwards from a horizontal position shown in Fig. 5. Another special element of the device according to the invention is the support 30 which is disposed between the conveyor belts 4, and which is an upward-facing U-shaped section. The legs of the U-shaped section are directed apart according to a predetermined angle, adapted to the trays to be stacked. The U-shaped support 30 (see Fig. 3) is fixed on a vertical pin 31, which is accommodated in a cross bar 32 of the frame. The pin 31 can move freely up and down in the vertical direction in the through hole 33 provided in the cross bar 32. The bottom side of the pin 31 is provided with a cam follower 34. It rests freely on a cam disk 35, which is mounted on a through-going shaft 36, which forms part of the frame 1. The cam disc 35 is flanked on one side by a gear wheel 37 fixed thereon and on the other side by a second cam disc 38 fixed thereon. The second cam disc 38 mates with the cam follower 39, which is fixed on an arm 40, which at the bottom end is swivellably mounted in the frame 1. Fixed at the free top end thereof by means of the hinge 41 is an arm 42, which is hingedly connected to an arm 43, which is fixed to the pin 31 and at right angles thereto. For the sake of completeness, it is pointed out that the cam follower 34 can move via a swivel arm 44 mounted in the frame 1 in an upward and downward direction according to the arrow P3. The cam disc 38 is star-shaped, three projecting cams 45 alternating with dips 46 ensuring that the cam follower 39 makes the arm 40 swing to and fro in the direction of the arrow P4. The swing of the arm 40 is transferred by means of the couple arms 42, 43 in such a way to the pin 31 that on maximum movement from left to right in Fig. 4 of the arm 40 an angular rotation of 90° is carried out on the support 30. On the return movement of the arm an opposite angular rotation of the support through 90° will take place. The cam disc 35 is provided with only one recess 47 in the periphery thereof, so that when there is a revolution of the cam disc 35 the cam follower 34 will sink into the recess 47, causing the support 30 to go into a lower position relative to the frame 1 or the conveyor belts 4. In the remaining part of the cam disc 35 the pin 31 with the support 30 is pressed upwards and will take up a high position relative to the frame or conveyor belts 4. The cam discs 35, 38 are fixed to the gear wheel 37, which is driven by a pinion 50. The pinion 50 is for this purpose fixed on a drive shaft 51, which can be rotated by means of a chain transmission 52 by a motor 53. On the same shaft 51 which is mounted in the frame provision is made for a second chain wheel 103, around which a chain 54 is passed. This chain 54 leads to a chain wheel 56 which is fixed on a shaft 57. The shaft 57 is mounted so that it is freely rotatable in the rollers 6 and is freely rotatable in the frame 1. The chain wheel 19 is provided at the end of the shaft 57 for driving the chain 16. The above-described device works as follows. When a tray S containing, for example, eggs and formed according to the standardized dimensions, is placed on the feed conveyor 2 or the working part of the conveyor belts 4, it will be moved to the right in Fig. 2 until the tray comes up against the stop 11. The motor 9 with a predetermined speed drives the belts 4. The motor 53 by means of the chain transmission 52, 54 drives the chain wheels 19 and consequently the two chains 16 in the direction of the arrow P5. The carriers 20 in the left part of the chain 16 (see Fig. 2) are thereby moved upwards, and the rake-shaped or fork-shaped elements 22 will fall into the sides of the tray S and carry this tray upwards. During the further conveyance the carrier 20 is conveyed over the horizontal part to the vertical part of the chain 16, taking with it the tray S which is supported by two opposite carriers 20 and fork-shaped elements 22 on either side. When the downgoing part of the chains 16 goes down the first tray comes to rest on the support 30, which is in the high position. The legs of the U-shaped section fall into the hollows on the bottom side of the egg tray, ensuring adhesion between support 30 and trays. When the carriers 20 drop further, the rake-shaped or fork-shaped element 22 can easily be removed from the hollows of the tray through the folding-up action of said element relative to the carrier 20 (see Fig. 5). The carriers can move freely down, and under the influence of gravity the element 22 will fall back on the stop 23 once space is given for it. In a higher stack this will last longer than in the case of a single tray. Due to the fact that there is a synchronism between the drive of the chain 16 and the drive of the cam wheel 38, once a tray is deposited on the support 30 the latter will be turned through 90° as a result of the turning of the cam disc 38 which handles the arm 40 and the turning of the pin 31. The released carrier is conveyed back again via the bottom chain wheels 18 and drive chain 19 to the pick-up position at the beginning of the feed conveyor 2. In this way a number, normally 6, of trays is always placed on the support 30, while after the placing of a tray the support 30 is turned through 90° or turned back so that the trays come to rest on each other turned alternately through 90°. This increases the total stability of the stack which has been formed. Once six trays are placed, the cam wheel 35 will be turned through one revolution, as a result of which the recess 47 comes to rest at the cam follower 34, enabling it to drop, taking the pin 31 with it. The support 30 falls to a low position, thereby causing the bottom side of the tray to come into contact with the top side of the working part of the belts 4. Once sufficient friction has been produced between belt and tray, the total stack will be pushed from the support 30 and taken along to the end stop 11 at the end of the discharge conveyor 3. This conveyor 3 is at such a height that the stack can be removed by hand. The pick-up mechanism for the trays can be designed differently, depending on the type of tray which has to be stacked. The same applies to the shape of the support 30, which can be of any desired shape. The surface layer of the support 30 can also be adapted to the type of tray.

Claims: 1. Device for stacking trays, comprising a feed conveyor (2) carrying the trays (S) one after the other and a discharge conveyor (3) for stacks of trays, further comprising a transport mechanism (15) with up and down moving carrying members (20) for carrying the trays one by one to a support platform (30), which platform is provided with means for a down an upward movement as well as for an oscillating movement through a 90° angle around a vertical axis of this support platform, characterized in that: the movement of the feed conveyor (2) for the separate trays and the movement of the discharge conveyor (3) for the stacks of trays have the same direction and in that the down- and upward movement of the support platform (30) is only activated after reaching the intended stack height of trays upon the platform and prior to the start of the next stacking cycle. 2. Device according to claim 1, characterized in that the transport mechanism (15) comprises two endless conveyors (16), disposed one on the left and one on the right side of the feed conveyor (2) and of the discharge conveyor (3) each of said endless conveyors carrying forks or rakes (22) each upwardly pivotable connected with their pivotaxis horizontally disposed to the conveyer, which forks or rakes are capable of simultaneously engaging opposite side edges of a tray to transport the tray form the feed conveyor to the support platform (30). 3. Device according to claim 1 or 2, characterized in that the discharge conveyor (3) comprises two parallel and spaced flights (4), the support platform (30) being mounted between said flights with its horizontal support surface parallel with the topsides of said flights and between the downgoing part of the endless conveyor (16) of the transport mechanism (15). 4. Device according to claim 3, characterized in that the feed conveyor (2) and the discharge conveyor (3) comprise a single endless conveyor consisting of two parallel flights (4) passing around a plurality of guide rollers (6,7) mounted at different height levels such that the discharge conveyer (3) is lying at a different height level compared to the feed conveyor (2). 5. Device according to any claims 1-4, characterized in that a double cam-mechanism (35,38) is provided for the lifting and the oscillation of the support platform (30).

Inventors: ANTONIS, MATHEUS EVERARDUS
Applicants: FPS FOOD PROCESSING SYSTEMS B.V.
Application year: 1989
Main classification: B65G57
IPC codes: B65G47, B65G57