Abstract:
A stacking column for recieving and holding a plurality of substantially flat workpieces, having a plurality of pawls mounted for movement on pawl bearings inside a frame and each having a workpiece stop, individually triggerable latching pins for individually fixing pawls in their workpiece-holding positions, and an erecting mechanism for erecting a next pawl needed for receiving a workpiece.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a stacking column for receiving and holding a plurality of flat workpieces. 
     2. Related Art 
     In just-in-time production and the outsourcing of portions of a production process, major portions of semi-fabricated products and outsourced parts must be shipped from producers to assemblers under strict deadlines. In order to reduce shipping costs, the parts to be delivered must be packaged in a space saving manner and arranged efficiently on some shipping medium. This requirement frequently is not compatible with safe and damage-free transportation. 
     Specifically, there exists in the automotive industry a need to transport major quantities of similar parts made of sheet metal or glass which are substantially flat. This usually is done in so-called stacking columns, which in turn are arranged in shipping containers. The stacking columns are intended to maintain the flat parts in a uniformly spaced relationship precluding mutual damage. 
     A drawback of these shipping containers is that the work-pieces cannot be locked or latched in place individually; instead, all of them are locked at the same time. Further, the locking mechanism employed in prior stacking columns makes them unsuitable for the use of robots. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide structure permitting workpieces to be locked separately and suited to be loaded and unloaded by means of a robot. 
     This object is achieved by a stacking column including a plurality of pawls mounted in a frame for movement in pawl bearings and each having a workpiece stop, latch pins adapted to be triggered individually to individually lock the pawls in their workpiece-holding position, and erecting means for erecting a subsequent pawl needed for receiving a workpiece. The erecting means are in the form of a cam and a hammer head on the pawls, with the erecting movement of a preceding ding pawl moving the subsequent pawls to an armed position. In another embodiment of the inventive mechanism, the cams are arranged one behind the other. When the column is being loaded, the workpiece is pushed over the top edge of the frame, with workpiece contact with the workpiece stop causing the pawl to be moved from the armed to its erected position. 
     After a pawl has been moved to its erected position, the latching pin drops into its latching position in front of the pawl, so that the pawl cannot move back into its lying or armed position. 
     In order to enable each pawl to be latched individually, each has a latching pin associated with it. The latching pins are mounted for independent movement on a pin shaft. The pin shaft has unlatching cams thereon effective to remove all latching pins from their latching positions in unison. An unlatching lever is provided to turn the pin shaft so as to lift the latching pins from their latching positions. 
     The inventive structure achieves maximum functionality when oriented horizontally. However, a lateral sloping angle of 90° to 45° is possible. Modifying the cam to act as a lifting cam will ensure functionality in the range of 0 ° to 45°. In this embodiment, the latching mechanism remains the same. 
     The movable parts —such as the receiving surface, the cam, the latching pins, and the unlatching cam shaft—referably are made of stainless steel. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein. 
     FIG. 1 shows a partial side view of a stacking column comprising a frame delimited by a frame end panel, a plurality of pawls disposed within the frame, with one of said pawls held in its armed position, latching pins mounted for movement on a pin shaft, and unlatching cams disposed alone the cam shaft to lift the latching action; 
     FIG. 2 shows a partial side view of the stacking column of FIG. 1, including a pawl in its erected position to support a workpiece and having moved another pawl to its armed position; 
     FIGS. 3 a ,  3   b ,  3   c  and  3   d  show various views of a pawl, including a cam, a hammer head, a workpiece stop and a pawl bearing; 
     FIG. 4 shows a front view of a stacking column of FIG. 1 including a frame end panel and a pawl in its armed position and with its latching pin not in its latching position; 
     FIG. 5 shows a front view of the stacking column of FIG. 4, including an unlatching lever acting on the pin shaft; and 
     FIG. 6 shows a partial plan view of the stacking column of FIG. 1 without the second frame end panel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIGS. 1 and 2, a stacking column  10  comprises a—preferably—U-shaped supporting member in the form of a frame  21  delimited by frame end panels  22 . Within frame  21 , a plurality of pawls  16 ,  16   a ,  16   b  are mounted for rotary movement about pawl bearings  20 . Pawls  16 ,  16   a ,  16   b  include workpiece stops  19  to engage workpieces  23  prefabricated to be substantially flat by deep-drawing, pressing, punching or the like. 
     The substantially flat workpieces  23  are aligned for shipment and fixed in position by workpiece stops  19 . When stacking column  10  is oriented horizontally, the weight distribution of pawls  16 ,  16   a ,  16   b  causes them to tilt forwardly. As a result, the top edge of pawls  16  comes to lie below the workpiece depositing edge  24  of frame  21 . 
     In another embodiment of the invention, pawls  16 ,  16   a ,  16   b  are moved by springs (not shown) to their lying position. 
     This makes it possible to use the stacking column in a vertical orientation also. 
     Each pawl  16 ,  16   a ,  16   b  has a cam  17  and a hammer head  18  to act on and orient the adjacent pawl. Hammer head  18  urges pawl  16   a  into an armed position as soon as a workpiece  23  has urged the preceding pawl  16   b  into its armed position. In the erecting movement of pawl  16   b , hammer head  18  is moved to turn about the pawl bearing  20  of the subsequent  16   a  so as to lift pawl  16   a  by exerting pressure on the lower workpiece stop  19 . 
     The angle of rotation of first pawl  16   a  is limited by a pawl stop  27  so that it initially assumes its armed position even without a workpiece  23  being present. 
     FIG. 2 shows a pawl  16   a  in its armed position. Pawl  16   b  has been erected by workpiece  23  which preferably may have been pushed by a robot across the depositing edge  24  of frame  21  in a direction towards pawl  16   b . As workpiece  23  contacts workpiece stop  19 , pawl  16   b  is turned into its erected position. This movement initially raises latching pin  11 ; its weight distribution then causes it to drop in front of pawl  16   b  along workpiece receiving back  19 . As a consequence, latching pin  11  prevents pawl  16   b  from dropping back into its armed or lying position. 
     In another embodiment (not shown), a spring is provided to urge latching pin  11  into its latching position in front of pawl  16   b . This ensures indentical functionality without dependence on a horizontal orientation of stacking column  10 . 
     Latching pins  11  are mounted on a pin shaft  12  extending along the entire length of frame  21 . In the area where pawls  16 ,  16   a ,  16   b  are mounted, pin shaft  12  has unlatching cams  13  thereon shaped to lift latched pawls  16   b  by a rotation of pin shaft  12 . Pin shaft  12  is journalled in pin shaft bearings  25  connected with frame  21 . 
     As shown in FIG. 5, pin shaft  12  has at least one end thereof an unlatching lever  14 ; unlatching lever  14  may be rotated to raise latching pins  11 . 
     FIGS. 3 a ,  3   b ,  3   c  and  3   d  show a possible configuration of pawl  16 . Hammer head  18  and the associated cam  17  is connected with workpiece stop  19  to form a L-shape, with pawl bearing  20  extending through the intersection of the two legs of the L-shape. 
     As hammer head  18  is a heavy solid member, workpiece stop  19  slopes downwardly in a rotary bearing. As shown in FIGS. 3 a  and  3   b , hammer head  18  is preferably connected to workpiece stop  19  in an offset position, with hammer heads  18  alternatingly disposed on the righthand side of line A—A (also shown as a centerline in the figures) and on the lefthand side of line B—B to keep the mutually lifting pawls  16   b ,  16   a  from interfering with each other. 
     In another embodiment (not shown), the cams are disposed one behind the other and shaped differently. 
     In dependence on the configuration of workpiece  23 , workpiece stops  19  are shaped differently. If workpieces  23  are high and planar, workpiece stops  19  are higher as well. 
     FIGS. 4 and 5 show the offset arrangement of hammer head  18  and cam  17 . They also show the U-shape of frame  21 , which is limited on one side by a frame end plate  22 . Frame end plate  22  preferably serves to secure stacking column  10  inside a shipping container (not shown). 
     FIG. 5 shows unlatching lever  14  integrally connected with pin shaft  12 . Turning unlatching lever  14  causes latching pins  11  to be moved into their erected positions. Thereafter, latching pins will immediately assume their armed position again for latching pawls  16   a ,  16   b ,  16 . This releases pawls  16   b , which drop to their lying or resting positions. 
     FIG. 6 shows a plan view of stacking column  10 . As may be seen, pin shaft bearings  25  are provided at both ends inside frame  21 . Also, each pawl  16  has a pawl shaft  26  associated with it which extends inside the frame at a right angle to sectionline A—A from one side of frame  21  to the other. These pawl shafts  26  movably mount pawls  16  in pawl bearings  20 .