Handling: hand and hoist-line implements – Grapple – Slideable jaws
Patent
1996-04-19
1998-06-09
Kramer, Dean
Handling: hand and hoist-line implements
Grapple
Slideable jaws
294 83, 414941, B25J 1510
Patent
active
057623910
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a gripper for disk-shaped articles with at least a roughly circular outside periphery, with a base body, with gripping claws which are guided to move radially to the inside and to the outside relative to the base body, and which are intended to abut the outside periphery of the disk-shaped article, with elastic means which load the gripping claws radially to the inside, and with spreading means in order to move the gripping claws to the outside against the action of the elastic means, the gripping claws being attached to mountings which are attached to guide rods which are guided to move in guide sleeves which are inserted in the base body. A gripper of this type is known from U.S. Pat. No. 4,453,757.
2. Description of the Related Art
In practice, there often arises the problem of grasping disk-shaped articles such that neither the top nor the bottom of the disk-shaped article is touched, that therefore the disk-shaped article is grasped and held only on its outside periphery (outer edge). This problem arises for example in the handling of silicon wafers, with surfaces which may not be touched when the wafer is held by a gripper.
In the gripper known from DE-A-3 915 038 there are holding arms which act on the edge of a disk-shaped article and which can be adjusted using hydraulic motors along paths of motion which are at an angle to one another. In this case the holding arms are to be moved toward or away from one another by piston-cylinder units. In the piston-cylinder units there are coil compression springs which act on the cylinders and which are designed to press them back into their initial position (position of the gripping fingers drawn near to one another).
In U.S. Pat. No. 4,453,757 the spreading means is a part which can twist in a base body and which is raised and lowered relative to the base body during twisting as a result of the grooves which are provided in its outer periphery and which interact with guide rollers located in the base body. To actuate the gripping claws there are other grooves which have a changing depth so that when the cylindrical part is turned opposite to the base body the gripping claws can be adjusted radially to the base body.
This combination of two movements which are aligned perpendicularly to one another (radial adjustment and raising and lowering) is of great importance for the grippers of U.S. Pat. No. 4,453,757, since in this way the gripping claws are to be prevented from rubbing against the bottom of the wafer when it is grasped.
A device for spreading elastic rings is known from DE-U-92 04 457.3. In this device, by means of the conical spreading means mountings for spreading fingers can be adjusted radially to the outside against the force of the springs in order to spread an elastic ring. To place the elastic ring spread in this way on another part there are additional fingers which strip the ring from the spreading fingers.
From IBM Technical Disclosure Bulletin Vol 27, No. 7B (December 1984) a mounting for disk-shaped articles is known which has three gripping elements. Each gripping element carries a grooved roller, the disk-shaped article, when it is held by the mounting, fitting with its edge into the grooves of the rollers.
U.S. Pat. No. 04 227 851 shows a manipulator with swivelling gripping claws. In this manipulator known from U.S. Pat. No. 4,227,851 the gripping claws which are swivel-mounted in a tubular carrier are loaded by a tension spring. To actuate the gripping claws, within the tubular body there is a floating piston which acts on the sloped surfaces of the gripper to spread then when the pressure medium is applied.
SUMMARY OF THE INVENTION
The object of the invention is to devise a gripper of the initially mentioned type in which the aforementioned problems are solved and which has a simple and reliable structure.
This object is achieved according to the invention with a gripper which is characterized by the fact that guide bodies which are guided in guide
REFERENCES:
patent: 3170322 (1965-02-01), Cavanaugh
patent: 3715048 (1973-02-01), Raab
patent: 4227851 (1980-10-01), Beezer
patent: 4453757 (1984-06-01), Soraoka
patent: 4676541 (1987-06-01), Lord et al.
patent: 4705313 (1987-11-01), Radice
patent: 4707013 (1987-11-01), Vranish et al.
patent: 4861086 (1989-08-01), Toral
patent: 5125708 (1992-06-01), Borcea et al.
patent: 5520501 (1996-05-01), Kouno et al.
Nicholls, "Centering Mechanism for Robot Disk Holder", IBM Technical Disclosure Bulletin, vol. 27, No. 7B, Dec., 1984, p. 4472.
Kramer Dean
SEZ Semiconductor-Equipment Zubehor fur die Halbleiterfertigung
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