Material or article handling – Device for emptying portable receptacle – Nongravity type
Reexamination Certificate
1999-03-26
2001-05-08
Fischetti, Joseph A. (Department: 3652)
Material or article handling
Device for emptying portable receptacle
Nongravity type
C414S416060, C414S799000, C414S810000, C053S235000
Reexamination Certificate
active
06227787
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a device for the automatic handling of delicate workpieces, consisting of at least one workpiece pallet for accepting the workpieces in a receiving region, the workpiece pallet comprising preferably straight rods disposed in grid and/or comb-like manner with free spaces between the rods, at least one workpiece gripper for depositing the workpieces on a surface provided for this purpose, and a pallet gripper for holding the workpiece pallet.
PRIOR ART
Workpiece pallets of this kind are used, for example, to hold metal parts which are placed in a heat treating furnace for heat treatment, an electroplating bath for galvanic surface treatment, or on special conveyor systems for transport through a continuous furnace. The workpiece pallets are usually made of special steel with suitable high-temperature strength. Particularly when using workpiece pallets of this kind in heat treating furnaces, carburisation of the steel an result in substantial elongation of the workpiece pallet. In addition, thermal stresses are generated which cause considerable deformation of the workpiece pallet.
The workpiece pallets are loaded with workpieces either manually or automatically using a suitable material handling machine. If the delicate workpieces are loaded onto the workpiece pallets by a piece-worker, they are often not handled gently and with the necessary care. In this context, even minor damage, which can occur by dropping the workpiece on the workpiece pallet, for example, already results in rejects.
The direct, automatic loading of the workpiece pallets, where the workpieces are deposited at a specified point and at a defined height, is also difficult. Releasing a workpiece in a specified position leads to a situation where the workpiece either drops onto one type of workpiece pallet, or is pressed down onto another. In both cases, delicate workpieces are very easily damaged by a hard landing on the workpiece pallet, or by being pressed down on it.
OBJECT AND SUMMARY OF THE INVENTION
The invention is based on the object of designing a simple and inexpensive device with which workpiece pallets can be loaded automatically, rapidly and precisely, and delicate workpieces handled gently.
According to the invention, the object is solved in that at least one positioning device with recesses is provided, into which the rods of the workpiece pallet can be lowered, that the positioning device has a positioning surface for depositing the workpieces by means of the workpiece gripper, and that the pallet gripper is designed such that it can lower the empty workpiece pallet from a lowering position lying above the empty positioning surface, through the plane of the positioning surface and into a receiving position lying below the positioning surface, such that the receiving region of the workpiece pallet is lower than the positioning surface and, after depositing the workpieces on the workpiece pallet lowered below the positioning surface, the workpiece pallet can be raised out of the receiving position such that the work pieces are raised from the positioning surface by the workpiece pallet.
The positioning surface of the positioning device advantageously serves as a support plane onto which delicate workpieces can be dropped or pressed without being damaged. The pallet gripper preferably operates automatically and is program-controlled. It can be raised from the receiving position as slowly as desired. In this way, the workpieces can be raised from the positioning surface of the positioning device very gently by the receiving region of the work piece pallet. The pallet gripper then places the workpiece pallets with the workpieces on a conveyor system of a continuous furnace, for example, or some other feed system for a subsequent production step. The workpiece pallets used can expediently be stacked in both empty and loaded condition.
For the sake of simplicity, the positioning surface of the positioning device is provided on a positioning block. This positioning block has pocket-like recesses which are simple to manufacture, into which the rods of the workpiece pallet can be lowered. Of course, the positioning device can be of any suitable design which results in a positioning surface which acts as a support plane.
In order to systematically rule out any damage to the delicate workpieces, the positioning block is made of soft material, preferably plastic.
The workpiece pallets can be grid-like pallets, the lattice members of which are connected to transverse rods at both ends. On the other hand, pallets with comb-like rods can also be used, the rods of which are firmly connected to the workpiece pallet at one end, the other end being free. Workpiece pallets which are of a combined grid and comb-like design can also be used. The shape of the recesses depends on the type of workpiece pallet used.
The pocket-like recesses of the positioning block can be designed as simple-to-manufacture, continuous grooves. The grooves can intersect, for example, so that grid-like pallets can be lowered into the positioning block. The remaining areas of the positioning block, which make up the positioning surface, pass through the free spaces between the lattice members.
For the sake of simplicity, the side walls of the recesses are positioned essentially parallel to the lowering and raising direction of the workpiece pallet.
The rods of the workpiece pallet can advantageously be lowered into the positioning block at a lateral distance from the walls of the recesses on all sides. This measure makes it possible for even severely deformed workpiece pallets to still be easily lowered into the recesses of the positioning block and lifted out again, without becoming caught in the positioning block.
Workpiece pallets which have at least one peg or the like with an undercut, can be picked up by a pallet gripper with at least one claw. In this case, the pallet gripper advantageously picks up the workpiece pallet by the existing undercut.
The workpiece pallet picked up by the pallet gripper is usually suspended from the pallet gripper and can swing slightly back and forth. In order to prevent such swinging back and forth and to achieve good hold in the specified position, the pallet gripper can be provided with at least one additional support pin, with which the pallet can be held in a design specified transport position relative to the pallet gripper.
In order to hold the workpiece pallet in the specified transport position, the support pin is expediently spring-loaded and presses on the workpiece pallet. As a result, the claw pulls up on the workpiece pallet while the support pin presses down on the workpiece pallet, such that it is held firmly in the specified position.
If workpiece pallets are used whose receiving regions are provided with workpiece mounts in the form of arbors in order to accept workpieces with holes, the problem arises that the positions of the arbors also change due to the change in length and deformation of the workpiece pallet. Nevertheless, the workpieces can still be deposited precisely in the specified position on the positioning block. In this case, the arbors are not positioned in the centre of the holes in the workpieces when raising the workpieces, but rather eccentrically. This eccentric position may merely not be located completely outside the diameter of the hole, so that the workpieces can be centred on the arbors. The workpieces are not dropped onto the arbors or pressed onto them, but rather lifted gently from the positioning surface by slowly raising the workpiece pallet. There is no damage to the workpieces.
Of course, workpiece pallets with so-called nests can also be used instead of those with arbors. In this context, a nest is positioned on the receiving region of a workpiece pallet and has a protruding rim which at least partially surrounds a workpiece, such that the workpiece is held firmly inside the rim with a little clearance to the rim. Workpieces of any kind can be deposited in the nests. In particular, workpieces without hole
Browdy and Neimark
Fischetti Joseph A.
Hermann Spicher GmbH
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