This invention relates to an apparatus for placing horizontally oriented plates into stacks at a high rate of speed and in a delicate manner.
In the production of storage batteries horizontally oriented plates leave an enveloping apparatus serially or in small groups, and these groups must be placed into stacks and the stacks oriented vertically for further processing. A prior art apparatus for accomplishing this objective is shown in Johnson et al., U.S. Pat. No. 4,824,307. Johnson et al. utilizes a series of paddles on a conveyor that comprises a pair of endless chains. The paddles are arranged in pairs that define pockets which carry the stacks. The stacks are formed when a pair of paddles is placed at the end of the conveyor so that the pocket is open and the plates can be dropped into it off the end of a conveyor that carries them horizontally. When a stack is formed the chains are advanced to orient the newly-formed stack vertically and position the next pair of paddles in the proper position to receive plates. This apparatus has several shortcomings which limits its ability to handle delicate plates and to stack plates at high speeds.
As the plates are dropped off of the end of the conveyor they rotate to near the desired vertical orientation and this rotation requires a long drop which creates an impact upon landing that can damage delicate plates. In addition, the long drop causes the plates to float which results in their being misaligned when the stacks are formed. Thus, the device disclosed in Johnson et al. has an alignment apparatus which adds to its overall expense.
In addition, after each stack is formed the paddles advance, with the newly-formed stack being rotated to a completely vertical orientation and the next set of paddles is placed at the end of the conveyor to form an opened pocket. This advancement must be accomplished while the area above the paddles is free of plates. Since the advancement takes some time to accomplish there is a limit to how fast the plates can be fed to the stacking apparatus on the conveyor and still not have interference.
The subject invention overcomes the foregoing shortcomings and limitations of the prior art by providing a conveyor system for transporting horizontally oriented thin rigid plates, in groups of one or more plates, in a manner such that the groups can be displaced from the conveyor system by placing a stop in front of them so as to prevent their continued movement when the conveyor system continues to operate. Thus, the plates displaced from the conveyor drop into stacks while they remain horizontal, thereby permitting the drop distance to be minimized.
In a preferred embodiment of the invention this is accomplished by making the space between the chains in the conveyor system greater than the width of the plates and placing inwardly extending support pads on the chains that engage the side margins of the plates. The support pads are placed in spaced-apart sets with each set having a length approximately equal to the height of the plates, and each set being separated from its adjacent set by a distance that is sufficient to allow the plates to pass between them.
In one embodiment, the stop is the paddles of the device disclosed in Johnson et al. In another embodiment the stop is located on the piston of a piston cylinder that is arranged so that the stop engages the group of plates when the piston cylinder is extended and does not engage the group when the piston cylinder is retracted.
The invention also includes a sorting apparatus that permits selected groups of plates to be removed from the conveyor system before the groups are displaced to form the stack. Thus, reject plates can be removed while the plates are being processed.
The invention also includes provisions for varying the distance between the conveyor system and the device that collects the displaced plates. As a result, the collection device can be lowered by a distance equal to the thickness of a group of plates each time a group is displaced so that every group drops the same distance.
Finally, the invention provides a transfer conveyor that operates at a lower speed than the conveyor system and receives some or all of the groups of plates and delivers them to the stacking apparatus. This causes the groups of plates to arrive at the stacking apparatus at a slower speed than they would if they came directly from the conveyor system. Therefore, there is more time for the completed stacks to be moved out of the way and not interfere with the arriving groups of plates of the next stack, and the apparatus can be operated at a higher rate of speed.
Accordingly, it is a principal object of the subject invention to provide a plate stacking apparatus in which plates transported in spaced-apart, horizontally oriented groups on a conveyor are slid off the conveyor and collected in stacks while remaining horizontal, thereby only requiring the plates to drop a short distance.
It is a further object of the present invention to provide such a device in which the chains of the conveyor that carry the plates are spaced apart by a distance that would permit the plates to drop between them and has inwardly projecting supports that engage the edges of the plates.
It is a further object of the subject invention to provide such a device in which each group of plates in a stack drops the same distance as every other group.
It is a still further object of the subject invention to provide such a device in which the plates are presented to the stacking apparatus which orients them vertically at a speed that is slower than the speed at which they are transported on the conveyor.
It is a still further object of the subject invention to provide such a device which permits defective groups of plates to be removed from the conveyor before they reach the stack so that a full size defect-free stack is always formed.