Apparatus for piling flat workpieces
United States Patent Brockmiiller 1 Apr. 29, 1975 [5 APPARATUS FOR PILING FLAT 3.596.575 8/1971 Brockmuller 198/35 WORKPIECES 3.683.758 8/1972 Feldkamper....  
  3.768.382 10/1973 Zernov ct a1. 93/93 DP [75] Inventor: Friedrich Franz Br kmull R2054] 10/1937 Staude 198/35 Lengerich of Westphalia. Germany [73] Assignee: Windmoller &amp; Holscher, Lengerich pmfwry Blunk of Westphalia German. Ass/stun! ILA&#39;UHIHMf-RIChZlTd K. Thomson l Attorney. Agent. or Firm-Fleit &amp; Jacobson [22] Filed: Apr. 5. 1972 21 Appl. No.: 234.729 1 1 ABSTRACT A method of stacking flat workpieces such as tube U S Cl 9V9 DP. 198/ portions. in which the front workpieces of a succes- I] i sion of workpieces in an overlap formation are ar- Fieid 182 rested and delayed. still overlapped. from moving to 271/46. 229. 230. 231: 93/93 C. 93 DP the stacking station until the preceding stack being formed is completed and moved away. The front workpieces are then released and form the bottom workpieces of new stack. The apparatus has arresting means for delaying the workpieces in their overlapped formation at the discharge end of a belt for feeding the workpieces from a workpiece processing machine to a stack-forming belt.  
 5 Claims. 4 Drawing Figures PMENTED RZ BYS ShEET 1 ii? 2 APPARATUS FOR PILING FLAT WORKPIECES This invention relates to methods of piling flat workpieces. such as tube portions, which are advanced in an overlap formation from a tube-making machine. and to piling apparatus for carrying out such a method.  
  A piling apparatus has been proposed in which tube portions are advanced in overlap-formation succession by continously moving individual conveyor belts arranged at a lateral spacing from each other. each first tube portion of a pile to be formed being held by suction means which engage its rearward end from belowbetween the conveyor belts. and at its forward end by slide bars which are also arranged between the belts. until a conveyor belt which is arranged downstream thereof and which temporarily moves faster than the first mentioned conveyor belts. has conveyed the tube portions thereon into the following pile-forming station proper. for forming the preceding pile; the last tube portions which in the overlap formation lie partially below the arrested first tube portion of the following pile to be formed, are pulled out by means of pressure rollers which co-operate powerfully with the adjacent guide roller of the second conveyor belt, and pass below the pressure roller and the clamp members which are applied lightly thereto.  
  The first tube portion of the next pile to be formed is arrested until the second conveyor belt has been cleared. During this period the following tube portions of the group advanced by the tube-making machine are pushed together on top of the arrested tube portion. and braking belts which extend from the clamp or arresting members against the direction of conveyance above the tube portions and which are advancingly pressed with a yielding pressure against the arriving tube portions by means of guide rollers arranged on a carriage, ensure that the overlap spacings of any tube portions which are to be pushed more closely together are uniformly reduced.  
  After the second conveyor belt has been cleared, it is reduced in speed to that of the first conveyor belt and the suction means and the clamp members are released so that firstly the overlapped tube portions which are now of reduced overlap in their front part. and then the normally overlapped tube portions, are conveyed onto the second conveyor belt until the number of tube portions required for a pile has passed through, whereupon the above described process is repeated.  
  Such a piling apparatus can be very expensive and can also suffer from the disadvantage that the tube portions which are partially below the arrested tube portion and which are to be advanced to the preceding pile must be advanced against the action of the two clamp members which are lightly applied thereto, for which purpose special pressure rollers with a strong action are required.  
  Another piling apparatus has also been proposed which has a continuously moving overlap-formation take-off belt and downstream thereof a pile conveying belt which is at a lower level and which also moves continously. and in front of the delivery end of which is arranged a suction beam which is intended to hold the respective first workpiece of each pile to be formed, until the desired number of workpieces has been pushed over the arrested workpiece, and collected to form a pile or stack.  
  in this piling apparatus. it can occur that. after the suction beam action has been cut out and the formed pile has as a result been conveyed away with the pile conveying belt. individualtube portions are also pulled out of the continuously following group of overlapped tube portions. which had not completely reached the pile. such tube portions thus unacceptably projecting or hanging over to a greater or lesser extent at the rear of the pile. In other words. if the groups of overlapped tube portions are not precisely separated. it is not possible to form precise piles. which results in rejects in subsequent processing.  
  According to the present invention. there is provided a method of forming piles from flat workpieces. comprising advancing the workpieces in overlap-formation towards a pile forming station. forming a pile of workpieces with the desired number thereof. arresting the workpieces at the front of the overlap formation and retaining the overlap. for the period required for moving a pile out of the pile forming station. and releasing the overlapped workpieces after the pile has been conveyed away. so that they form the lowermost work pieces of the new pile.  
  The invention also provides apparatus for carrying out a method according to the immediately preceding paragraph. comprising an overlap-formation conveyor belt which in operation moves continuously. a piling belt which is disposed downstream of the overlapformation belt and which in operation is driven at least when changing piles; means arranged adjacent the piling belt for arresting and aligning workpieces thereon. which means can be moved away for conveying the piles away; and means arranged at the discharge end of the overlap-formation conveyor belt above and below the plane of conveyance thereof. for arresting a plurality of overlapped workpieces. the forward edges of which have already left the overlap-formation conveyor belt. which arresting means can be pressed towards each other at least during the time that the workpieces are arrested.  
  In a particularly advantageous construction. the arresting means can comprise pressure rollers or belts which also move during pile formation at the speed of conveyance of the overlap-formation conveyor belt and which are pressed from above and from below against the overlapped workpieces. wherein at least one of the arresting means can be braked during the pile changing operation. By braking the retaining means which are constantly pressed against each other, any workpieces therebetweeri at that moment are arrested until the arresting means are again released. The pressure rollers or belts can desirably be stopped by brake means which operate immediately, preferably magnet brakes.  
  In a particularly preferred embodiment of the invention, below the plane of conveyance is provided a pressure roller which is driven from the overlap-formation belt driving means by way of a friction clutch or the like, at the same peripheral speed as the overlapformation belt. the diameter of the pressure roller being smaller than that of the guide roller of the overlap-formation conveyor belt, while above the plane of conveyance is an endless pressure belt which passes over two guide rollers. wherein the pressure belt is driven by friction by the overlapped workpieces. The pressure roller which is arranged below the plane of conveyance and which is driven from the driving means for the overlap-formation belt. and which is of smaller diameter than the guide roller of said belt. acts as an ar resting means which co-operates with other arresting means and which can be stopped for the purposes of arresting a plurality of workpieces. The pressure belt which is disposed above the plane of conveyance ob viously a plurality of narrower pressure belts moving parallel to each other can also be provided is provided in accordance with the invention to ensure. while the forward end of the next following group of overlapped tube portions is arrested. that the following tube portions are pushed together uniformly. The pressure belts thus also act as braking belts.  
  A mounting frame carrying the pressure belt guide rollers is advantageously suspended swingingly about an axis lying between the guide rollers and extending transversely to the direction of conveyance. In this way the pressure belts can adjust themselves relative to the apparatus. to correspond to the narrower overlap which is formed. It is also desirable for the mounting frame to be longitudinally and vertically adjustably suspended. so that it can be adapted to different operating requirements. In particular. this makes it possible for the pressure belt and the support rollers to be precisely synchronised to each other. and for any corrections which may be necessary. at any time to be carried out.  
  A method and embodiments of apparatus. all according to the present invention. will now be described by way of example with reference to the accompanying drawings. in which:  
  FIG. 1 shows a diagrammatic side view of a first embodiment of the apparatus.  
  FIG. 2 shows an embodiment similar to that shown in FIG. I. but with an additional conveyor belt for use in high-speed machines. and an adjusting means for the pressure belt. which adjusting means is only diagrammatically indicated for the purposes of simplification.  
  FIG. 3 shows a diagrammatic side view on an enlarged scale of an embodiment corresponding to that shown in FIG. 1. with additional rollers serving as coacting holders or counter-pressure members for the lower run of the pressure belt. and  
  FIG. 4 shows a simplified plan view taken along the line lV-IV of the embodiment of FIG. 1.  
  workpieces l are continuously discharged at uniform spacings from a processing machine (not shown). for example a tube-making machine. and are ejected onto a belt conveyor which is formed by an overlapformation take-off belt 2 and which moves the workpieces in an overlapped formation in the direction of conveyance (as illustrated by arrow 4), to a pile forming or stacking station comprising a stacking r pile forming belt 3. The overlapped formation of the workpieces 1 is achieved by the overlap-formation belt 2 moving at a lower speed than the conveyor means (not shown) which removes the workpieces from the processing machine.  
  To form one of the piles of workpieces, the piles being indicated generally at 5 and 6 respectively, the succession of overlapped workpieces is interrupted after the last formed pile has reached a predetermined number of workpieces, so that the following pile of workpieces is at a given spacing relative to the preceding pile.  
  As shown in FIG. 1, above the upper run 3 of the piling conveyor belt 3 is a workpiece arresting and aligning means such as a stop plate 9 which is pivotal by means of levers 8 about a pivot axis 7 disposed below the upper run 3&#39;. While a pile is being formed, the stop plate 9 is located with its lower edge directly above the upper run 3 of the belt 3&#39;. after the pile has been formed. the stop plate 9 can be lifted so that it rests by means of a roller 10 rotatably mounted on its rear side, on the uppermost workpiece of the pile just formed. The stop plate 9 is preferably used in cases in which the piling conveyor belt 3 directly follows the overlapformation take-off belt 2, as in FIGS. 1 and 3.  
  In the embodiments shown in FIGS. 1 and 3, the movable stop plate 9 operates in combination with a suction beam 12 which is arranged downstream of the guide roller ll of the belt 2, and which is connected to a suction pipe 13. The overlap-formation take-off belt 2 carries a pressure roller 14 arranged downstream of its guide roller 11 in the direction of conveyance. The roller 14 is smaller in radius than the roller 11 and, extending parallel to the roller 11, is mounted by means of levers 15 on frame members 16 of the belt 2. Provided above the pressure roller 14 is a pressure member comprising two rollers 18 (FIG. 4) which are rotatably mounted in a frame formed by rods 17. In the embodiments illustrated, the rollers 18 form the downstream end, and rollers 31 form the upstream end. of a pressure belt assembly comprising two individual belts which are arranged at a spacing from each other transversely to the direction of conveyance (as is clearly visible in FIG. 4). the lower runs 19 of the belts 20 forming a barrier surface. The pressure belt assembly 18, 20 and 31 is longitudinally, transversely and vertically adjustable relative to the belt 2, and is also automatically pivotable about a transverse axis. To provide for such movements. the rods 17 which carry the rollers 18 and 31 are mounted in crosshead-like hinge members 38 which in turn are pivotally carried by a rod 39 extending transversely to the direction of movement of the belt 2, between the rollers 18 and 31. The rod 39 is mounted with its ends at a spacing above the belt 2 in crosshead members 40 which in turn are carriedby rods 41 which are releasably secured at their lower ends to the frame members 16 of the belt 2. By sliding the members 40 on the rods 41, the pressure belt assembly 18, 20 and 31 is vertically adjustable, while transverse adjustment is effected by sliding the members 38 on the rod 39. The rods 17 can be slid on the members 38 for longitudinal adjustment. The frame 17 is freely pivotal about the rod 39.  
  The drive for the pressure roller 14 in the present embodiments is derived by way of a belt 27 from the driving means (not shown) for driving the overlapformation take-off belt 2, the pressure roller 14 being driven at the same peripheral speed as the belt 2. The pressure roller&#39;14 can also be braked, independently of the movement of the belt 2 continuing. For this purpose, as shown in FIG. 4, arranged on a trunnion end portion 28 of the guide roller 11 of the belt 2 is a friction clutch which is indicated generally at 29, and a magnetic brake which is indicated generally at 30. Any suitable brake which is immediate in operation can be used. The transmission of drive between the guide roller I] and the pressure roller 14 can be interrupted by actuating the brake 30, so that the pressure roller 14 can be temporarily stopped while the belt 2 continues to move. The drive for the overlap-formation take-off belt 2 is derived from the processing machine which ejects the workpieces, with an interposed speed control transmission (not shown), and is in turn transmitted. also by way of a speed control transmission, to the piling conveyor belt 3.  
  Although, in the present embodiments. the pressure roller 14 is not separately driven, the guide rollers 31 which with the pressure rollers 18 carry the belts 20 also have a magnetic brake (not shown) so that. in addition to the pressure roller 14, the pressure belts 20 which move freely during conveyance, and the pressure rollers 18, can also be braked at the moment that the groups of overlapped tube portions are separated.  
  In all the embodiments illustrated, the magnetic brakes for the pressure rollers 14 and the pressure belts 20 are desirably actuated by way of a counting mechanism (not shown) which is controlled by the tube processing machine. so that a given number of workpieces, which is precisely determined by the counting mechanism, forms each pile.  
  FIG. 2 shows an arrangement in which a conveyor belt 32 which conveys to the piling conveyor belt 3 workpieces which leave the transfer position between the pressure roller 14 and the pressure rollers 18, is provided between the belt 2 and the belt 3, this arrangement being particularly suited for high-speed machines. In this construction, the workpieces 1 are accelerated by the conveyor belt 32 towards a stop plate or flap 33 which substantially corresponds to the stop plate or flap 9 of H6. 2. The stop plate 33 is pivotal in the directions indicated by the arrow 34 about a horizontal pivot axis 35, as soon as a finished pile has been formed on the piling conveyor belt 3. The interposition of the conveyor belt 32 makes it unnecessary to provide a suction beam such as 12.  
  Separation of the overlapped tube portions by means of the brakable rollers 14 and 31 is intended in this embodiment to suspend further movement of the overlapped portions until the flap 33 has closed again, after the preceding, finished pile has been conveyed away by the belt 3.  
  FIG. 3 shows on an enlarged scale a construction in which the barrier surface formed by the respective lower runs 19 of the pressure belts 20 can be braced in position by means of rollers 37 which are arranged at a spacing from each other along the length of the lower runs 19 and which are loaded by springs 36. This arrangement is used when it is preferred for the pressure belts 20 to be of greater length, and can prevent excessive sagging of the lower runs 19 when the belts 20 are elastic.  
  The apparatus according to the invention operates as follows:  
  The overlapped workpieces 1 coming from the processing machine are moved by the overlap-formation take-off belt 2 to the transfer position in the region between the pressure roller 14 and the pressure belts 20, from which they are moved on to the pile forming station 3. FIGS. l and 3 each show the working position in which a pile 5 has been formed and already moved forward a distance by the piling conveyor belt 3. Shortly before the position illustrated is reached. the stop plate 9 shown in FIG. 1 has been lifted from its position in which it is in contact with the edges of the pile 5 which are at the front in direction of conveyance. in order in that way to release the pile 5 which can then be carried away by the belt 3, and also to promote the removal of the pile, in that the stop plate 9 rests with its roller 10 on the top workpiece of the pile 5. At the same time as the pile 5 is finished and the stop plate 9 is lifted from its working position, the lowermost workpiece of the pile 5 which, while the pile was being formed, had been arrested by the suction beam 12 in the plane of the top run 3&#39; of the belt 3, was released by the suction beam 12, while the magnetic brakes of the rollers 14 and 31 were actuated and thus the pressure roller 14 and the pressure belts 20 were braked, thereby preventing further movement of the workpieces which at that moment were&#39;located between the pressure roller 14 and the belt 2 on the one hand, and the pressure belts 20 on the other hand. During this braking operation, the following workpieces accumulate between the top run of the continuously driven belt 2 and the lower runs 19 of the belts 20, by the workpieces coming to lie with their forward edges against the stationary lower runs of the belts 20, the workpieces being stopped in a position in which they closely and uniformly overlap each other.  
  The magnetic brakes are released as soon as the ends of the finished pile 5 which are at the rear in the direction of conveyance have passed the stop plate 9 and the pressure roller 10, so that the stop plate 9 can automatically be lowered onto the top run 3 of the belt 3, to take up its starting position for the next pile to be formed. The arrested, lowermost workpieces of the new pile to be formed still lie on the topmost workpiece of the finished pile 5, as shown in FIG. 1, while the pile 5 is moved on into the position of the pile 6 which had previously been formed, so that there is a sliding movement between the lowermost workpieces of the new pile to be formed and the uppermost workpiece of the pile 5. When the forward edge of the first workpiece of the new pile to be formed reaches the stop plate 9, after release of the magnetic brakes, the suction of the suction beam l2.is cut in by actuating a sensing contact (not shown), and arrests the lowermost workpiece at its rearward edge, while the forward edge of the arrested workpiece lies precisely against the stop plate 9. Due to the positive movement between the driven pressure roller 14 and the belt 2, and due to the pressure belts 20 lying thereon, the further workpieces of the succession of overlapped workpieces, which has been pushed together while the pressure roller 14 and the pressure belts 20 were stationary, are moved forward and tidily deposited on the lowermost workpiece which is already held by the suction beam 12, and also come to lie with their forward edges against the stop plate 9. Precise aligning of the workpieces within the pile to be formed is assisted by the relatively small diameter of the pressure roller 14, in conjunction with the arrangement of the suction beam 12 and the piling conveyor belt 3, which are lower by the thickness of at least one pile than the exit plane of the workpieces between the pressure roller 14 and the pressure belts 20.  
  When the new pile has reached the desired thickness, the stop plate 9 is lifted again by way of a sensing means (not shown) or a counting mechanism driven by the machine, while at the same time the pressure roller 14 and the pressure belts 20 are braked and the suction beam 12 is cut out so that the above described process of events is repeated in the same sequence.  
  Therefore, operation is no longer such that a given workpiece is arrested and any workpieces preceding it are advanced as the topmost workpieces to the pile being formed. but a part of a whole group of overlapped workpieces is arrested so that the following workpieces are pushed onto the last of the arrested workpieces.  
  The above described apparatuses also avoid the disadvantage of workpieces projecting out of the pile at the rear thereof, in that, at the moment that the suction beam 12 is cut out, any workpieces which have not fully arrived at the pile, are retained until the pile has cleared the pile forming station. This prevents workpieces which have not arrived completely at the pile being carried away therewith. so that only satisfactory piles are removed.  
  During the entire sequence of operations, the rollers 18, together with the lower runs 19 of the pressure belts 20, press the whole group of overlapped workpieces against the top run of the belt 2 and against the pressure roller 14. In addition, the adjustable belts 20 with their lower runs 19 pass the forward edges of the workpieces between the pressure rollers 18 and the pressure roller 14, and at the same time act as a barrier surface for the workpieces 1 which are sifting through during the braking process. This is facilitated in that the pressure belt assembly 18, 20, 31 can perform a free pivotal movement about the rod 39, in which case the lower runs 19 of the belts 20 automatically come to lie, with continuously increasing pressure, against the forward edges of the overlapped workpieces.  
  While, in the arrangements shown in FIGS. 1 and 3, the pile of workpieces is formed by means of the suction beam 12 directly downstream of the pressure roller 14 and the pressure rollers 18, in the apparatus shown in FIG. 2 the workpieces l are conveyed downstream of the pressure roller 14 by the conveyor belt 32 at a higher speed onto the piling conveyor belt 3, and against the stop flap 33 in front of which the pile is formed. In this arrangement the group of overlapped workpieces is arrested by the pressure roller 14 and the pressure belts 20, in each case for a period which is determined by the opening of the stop flat 33, removal of the finished pile and closing of the stop flap 33. In this arrangement the suction beam 12 with associated vacuum pump and control members can be omitted. In addition, it is possible, by varying the speed of the conveyor belt 32, to be able to use the piling apparatus for workpieces comprising different materials with very different properties.  
 I claim:  
 1. Apparatus for piling flat workpieces comprising a continuously moving overlap-formation conveyor belt followed by a piling belt which moves at least when changing piles, said piling belt associated with stop means for arresting and aligning workpieces thereon, in which said stop means is moveable away from said workpieces for conveying the piles away; wherein the improvement comprises: arresting means at the discharge end of the overlap-formation conveyor belt for arresting a plurality of overlapped workpieces, the forward edges of which workpieces have already left the overlap-formation conveyor belt, which arresting means exert pressure against the overlapped workpieces from opposite sides at least during the time the workpieces are stopped, said arresting means comprising pressure rollers and pressure belts which move during pile formation at the conveying speed of the overlap-formation conveyor belt and which develops said pressure which acts from above and below the overlapped workpieces; and wherein at least one of said pressure rollers or pressure belts can be stopped during the changing of piles by immediately acting brake means.  
  2. Apparatus according to claim 1 wherein the brake means are magnetic brakes.  
  3. Apparatus according to claim 1 wherein the arresting means includes a pressure roller which lies below the plane of overlap conveyance and which can be driven from the overlap-formation belt driving means by way of clutch means at the same peripheral speed as the overlap-formation belt, the diameter of the pressure roller being smaller than that of the adjacent guide roller of the overlap-formation conveyor belt, and above the plane of conveyance of the overlapformation belt at least one endless pressure belt which passes over two guide rollers, the pressure belt being driven in operation by friction from the overlapped workpieces.  
  4. Apparatus according to claim 3 wherein said two guide rollers are carried on a mounting frame which is supported so that it can swing freely about an axis.extending transversely to the direction of conveyance and lying between said two guide rollers.  
  5. Apparatus according to claim 4 wherein the mounting frame is longitudinally and vertically adjustably supported.