Handling: hand and hoist-line implements – Hook – hoistline – or grab type – Locking device
Patent
1993-10-28
1996-01-16
Kramer, Dean
Handling: hand and hoist-line implements
Hook, hoistline, or grab type
Locking device
294 97, 294115, B66C 142
Patent
active
054841810
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a gripper mechanism for a manipulator or the like in accordance with the preamble to claim 1.
Such a gripper mechanism is described in Federal Republic of Germany Patent 34 41 643.9. In that case, the gripper finger is guided as coupler of a six-member positive guide mechanism. The six-member guide mechanism consists of the combination of a special slider/crank mechanism, an equal-sided link quadrilateral, a special link quadrilateral, a link parallelogram in the manner that the slide of the slider/crank mechanism and the gripper finger together form two opposite links of the link quadrilateral. The slide link of the slider/crank mechanism and the drive of the gripper mechanism together form a single unit, the slide rod of the drive unit not carrying out any movement in the direction of the slide axis with respect to the gripper housing or frame.
In the invention according to Federal Republic of Germany Patent 34 41 643.9, the single slide rod of the centrally arranged drive unit serves as attachment member for the robot arm. This rod must extend through the movable cylinder and take up the entire lateral loads on the gripper, including the weight of the object as well as the dynamic transverse and torsional forces which are produced upon the transport and rotation of the object, and transmit them to the robot arm. In this way, this gripper mechanism is of very limited load-bearing capacity. It is torsionally and flexurally weak and, in the case of objects of greater weight, loses stability and precision of positioning.
Another gripper mechanism is known from EP 0 15 32 11. In that case, the gripper finger is guided on the frame as link of a six-member positive guide mechanism. The link of a link parallelogram which is opposite the gripper finger is driven by slide rod of a slide link which serves as actuating unit. In this connection, the gripper finger travels linearly up and down perpendicular to the slide axis along a guide plate which is fastened to the frame. In the case of the actuating unit, the slide rod is arranged centrally and movably and the cylinder is fixed on the frame.
SUMMARY OF THE INVENTION
In contradistinction to this, the object of the present invention is to make a gripper mechanism of this type flexurally and torsionally stiffer.
This object is achieved in accordance with the invention by the features set forth in claim 1.
The dependent claims contain advantageous further embodiments of the invention.
As a result of the development of the slide rod in the form of a cage which is formed of several decentrally arranged rods, a widening in cross section of the guiding and holding members of the gripper mechanism is obtained with simple means. In this connection it is advantageous if the slider is arranged as a carriage which extends along the rods and slides on the rods. By this arrangement an exact guidance of the slider is made possible, which, in its turn, imparts additional transverse and flexural stiffness to the rods. Another advantageous embodiment of the invention provides that, at the ends of the rod, clamping plates are arranged which make it possible to prestress the rods. In this connection, the rods can be prestressed either in compression or in tension. By this prestressing, a considerable increase in flexural and torsional stability of the cage is obtained. In order to obtain a prestressing of the rods in tension, they can be made hollow. In this case, the prestressing can be obtained by a prestressed threaded rod placed into the hollow rods. The movement of the slide relative to the slide rod can be obtained with a cylinder-piston arrangement. In this case, there is preferably arranged within the cage a piston rod with a stationary piston arranged in a cylinder associated with the slide. The movement of the cylinder relative to the piston is preferably controlled by pressure fluid. The feed of the pressure fluid to the cylinder is preferably developed by the hollow rods. In a preferred further de
REFERENCES:
patent: 3051327 (1962-08-01), Goodell et al.
patent: 4507045 (1985-03-01), Valentine et al.
patent: 4627654 (1986-12-01), Van Oost
patent: 4665558 (1987-05-01), Burke
patent: 4686870 (1987-08-01), Mack
Farber Martin A.
Kramer Dean
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