Chucks or sockets – Accessory or component – Padded or cushioned jaw
Patent
1991-12-10
1993-06-22
Bishop, Steven C.
Chucks or sockets
Accessory or component
Padded or cushioned jaw
811851, 269275, 294 8632, 294 991, 279 466, B23B 3110
Patent
active
052210995
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for conducting translational forces and/or torques into movable objects by means of clamping jaws which engage the objects.
When using devices of the above type, considerable clamping forces must be generated in order to lift or even shift heavy parts, for instance. Furthermore, large torques are required, by way of example, to screw pipes to or disengage pipes from one another. To achieve reliable transmission of the clamping forces to the movable objects, the clamping jaws are frequently equipped with blades. The blades or other elements which significantly increase the local contact pressure often damage the surfaces of the rigid objects to be moved or cause undesired indentations so that the damaged object surfaces undergo increased corrosion. For this reason, stainless steel is increasingly employed for borehole pipes in oil field technology. Due to cost considerations, long life is therefore of importance. Another drawback is that, after the clamping jaw blades have been pressed into the material and the bearing force has been released, the clamping jaw blades can frequently be disengaged from the gripped surfaces of the objects to be moved only with difficulty. This applies particularly to the disengagement of clamping blades from a pipe following an unscrewing procedure. Thus, subsequent to the complete release of a pipe from a connecting piece, it is very difficult to remove the clamping jaws from the unscrewed workpiece by reversing the direction of rotation because a countermoment no longer exists.
It is an object of the invention to design a device of the type referred to at the outset so that it is possible for the clamping jaws to grip the surfaces of the objects to be engaged and moved without damage. The solution according to the invention is characterized in that the clamping jaws are equipped with linings of elastomeric material serving as carrier material for a multiplicity of hard, small elements having tips which are directed towards the bearing surfaces of the objects to be clamped.
The invention makes it possible, largely independently of the material used, to transfer large translational forces directed perpendicular to the clamping forces, or large torques, to rigid objects to be moved without damaging their surfaces and thereby causing these to undergo increased corrosion. Even plastic objects can be engaged with drawbacks. This advantage is achieved by a combined frictional and configurational locking over a wide area. The elasticity of the carrier material provides for full surface-to-surface contact between the lining and the surfaces to be engaged even when these deviate from a completely flat or cylindrical shape and, for instance, have regions of greater or lesser unevennesses or curvatures.
The use of pin-shaped elements which are embedded in the carrier material is particularly advantageous. The ends of the pins at the gripping side essentially reach the surface of the lining lying against the objects to be moved while the ends of the pins at the side of the clamping jaws preferably terminate at a distance from the bearing surface of the elastomeric linings against the clamping jaws. The elastomeric material between the clamping jaws and the pin ends at the side of the clamping jaws can compensate for unevennesses of the parts to be clamped because elastomeric material can flow sideways at high pressure.
Other hard particles of granular form can be used instead of the pins. Crystalline grains of diamond, glass, corundum, quartz, ceramic and the like having the same size or different sizes are suitable for this purpose.
Additional features advantageous for the design of the invention are set forth in the subclaims.
Exemplary embodiments of the invention for transferring forces to objects to be moved are illustrated in the drawing purely schematically and described below.
There is shown:
FIG. 1 the cross section through a pipe with clamping jaws embracing the same,
FIG. 2 the longitudinal section A--B through the device of FIG. 1,
FIG. 3 an
REFERENCES:
patent: 1650101 (1927-11-01), Taylor
patent: 2765000 (1956-10-01), Bond
patent: 2793136 (1957-05-01), Root
patent: 3368252 (1968-02-01), Meek
patent: 3799010 (1974-03-01), Guier
Bishop Steven C.
Kontler Peter K.
Weatherford Products & Equipment GmbH
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