The present invention relates to a device for inserting and/or withdrawing particularly long and/or heavy materials in or from a storage container having preferably several horizontal and vertical rows, which device utilizes an elevating table positioned on a movable column structure, the elevating table having at least one gripper support which is equipped with at least one gripper device that is movable in its longitudinal direction for withdrawing material from the storage area and putting material into the storage area.
In known types of long-material stackers, the material to be put into or withdrawn from stock is generally stored in bins, each bin being kept in a storage area in a particular compartment identified by a horizontal row and a vertical row. It is necessary for such a bin to be made available and returned into the storage area as quickly as possible by means of such a long-material stacker. Such a bin is moved in and out by a gripper device which pulls the bin onto the gripper support and pushes it back into the storage area which is normally designed as a set of shelves. When the gripper device moves, it must be ensured that the bin can be picked up in its location in the storage area by gripper arms and held securely during the entire withdrawal movement. During the insertion movement into the storage area, the bin must again be held securely the whole time by the gripper arms, and above all it must be possible to position the bin very accurately in the storage area or in the set of shelves in order to ensure that the bins are always arranged in the same way relative to the front edge of the storage area and can be picked up with certainty during the next withdrawal operation. This means that the gripper device must always be able to pick up and release a bin in a defined position which is always the same.
In known devices of this kind, this has previously been achieved by the gripper device being controlled by limit switches on the gripper support, with the gripper arms themselves being controlled by suitably designed cam plates which have a fixed location. A disadvantage of this is that the limit switches reduce the working speed, that is, they operate with a loss of time, and thus the operation of the gripper device is delayed. If a limit switch fails, this can result in considerable damage to the entire device and/or to the storage shelves. Another disadvantage is due to the large size of construction which is necessary, because the gripper arms must interact with the cam plates through relatively large roller bearings on account of the high load which is in the region of about one ton. Because of this load on the gripper device when withdrawing or inserting the loaded bins, it is not possible to use a plain bearing or similar small-size element.
One object of the present invention is to produce a device of the type described at the outset in such a manner that the gripper device can be made considerably smaller and with which the material can be positioned more accurately especially when putting it into stock.