Work holders – Plural holders to hold workpieces relative to each other – Workpieces parallel to each other
Reexamination Certificate
2000-08-17
2002-08-13
Watson, Robert C. (Department: 3723)
Work holders
Plural holders to hold workpieces relative to each other
Workpieces parallel to each other
C269S087200, C269S249000, C269S258000, C269S268000
Reexamination Certificate
active
06431534
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a curvilinear clamping tool and more specifically to a substantially “C” shaped clamp which can be used to retain and hold the ends of two pipe sections together for welding.
BACKGROUND OF THE INVENTION
Throughout the ages, many tools, devices, and fixtures have been proposed and used for clamping and securement of workpieces. Examples of such devices include:
U.S. Pat. No. 5,135,209 to Penny relates to an apparatus arranged for selective mounting of plate-like coaxially aligned clamping plates, or alternatively the use of “V” shaped brackets mounted in a coaxially aligned relationship to clamp a pipe therebetween, wherein the brackets each include recesses formed at each side edge thereof, wherein the recesses are aligned relative to one another when secured together to provide access to a pipe joint positioned within the recesses for a machining procedure and the like.
U.S. Pat. No. 2,440,820 to Frank relates to clamps and has relation more particularly to a device of this kind of a “C” type, and it is an object of the invention to provide a clamp of this kind constructed in a manner to make the same particularly advantageous for use in holding the work against a seesaw type base.
U.S. Pat. No. 3,596,898 to Hillburn relates to a fixture for retaining the end of two pipe sections together during welding. The fixture comprises an upper clamp and a lower clamp, the lower clamp having an extension going out to one side and rigidly secured to an upstanding threaded rod. The upper clamp has an extension going out to one side and terminating in a sleeve, which is slidable up and down on the threaded rod but is not threaded to it. A wing nut or nut with a handle is threaded on the rod above the sleeve of the upper clamp and is used to tighten that clamp into place to hold the pipe ends firmly between the two clamp members. Central portions of the clamps are recessed to give greater availability to the welding fixture before the pipe has to be turned, so that only one turn is usually required to weld the entire peripheries of the two pipes.
U.S. Pat. No. 4,363,475 to McCarty relates to a vise-like C-clamp with adjusting screw and wherein two elongated square bars are fixedly attached to one jaw thereof and the clamping end of the adjusting screw whereby a pair of gripping heads may be selected from a group of variously shaped heads and oppositely and interchangeably arranged on each of the bars. The clamp may be hand held or adjustably mounted in a supporting base for gripping and positioning variously shaped work pieces in horizontal, vertical, and angularly held positions while work is performed thereon.
U.S. Pat. No. 4,747,588 to Dillhoff relates to a clamping tool for use in clamping and supporting a wide variety of elongated pieces for welding has a pair of generally C-shaped arms which support a pair of opposed L-shaped clamping members, one for each arm. Each clamping member has a long leg and a short leg, which extends perpendicular to the long leg, and each clamping member is supported on one of the arms for pivotal movement about two axes.
U.S. Pat. No. 5,090,670 to Yang relates to a C-clamp which may be clamped by a second C-clamp, so that large and irregular shaped workpieces may be clamped thereby, and further so that additional strength and stability is provided. The C-clamp includes an internal clamping face that contacts the workpiece during the clamping thereof. The C-clamp further includes a pair of external clamping faces that are contacted and clamped by the second C-clamp. The arm of the C-clamp that has the internal clamping face formed thereon has the external clamping faces substantially aligned therewith, so that vibrations produced by work being done on the workpiece are minimized. The clamp includes clamping heads that automatically pivot and swivel to accommodate the shape and angle of the surface and angle of the surface of the workpiece being clamped therewith.
It has been found that many prior art devices are deficient and cannot withstand the stresses placed on the same when subjected to high clamping torque common when tubes to be welded are misaligned, a common occurrence in boiler, refinery and other applications. Heating and cooling cycles common in welding can serve to weaken components generally utilized in the prior art, particularly the connection points between the clamping elements and feed screws. Thus, the prior art clamps are not suitable for welding operations and generally fail upon repeated use.
SUMMARY OF THE INVENTION
The present invention relates to an improved clamping tool for aligning and holding tubes, pipes, or solid round stock to be welded. The clamping tool has a curvilinear body or frame such as a traditional C-clamp which is well known in the art. The tool of the present invention has at least one solid angle clamping member which has been machine formed or cast from a single piece of metal and can be operably attached to an adjusting screw or clamping rod. The machined or cast solid or integral angle clamping member and adjusting screw are weldlessly connected to each other through the use of suitable attachment elements, such as spring pins. The weldlessly connected clamping member can withstand, without failure, high amounts of clamping torque and a plethora of heating and cooling cycles undergone while the tool is utilized to clamp or hold tubes to be welded together. The attachment elements also allow interchangeability of different sized clamping elements.
A further object of the present invention is to provide a clamping device, which is capable of clamping pipes or tubes of varying diameters. The clamping devices of the present invention can be used to clamp tubes having a diameter generally from about 0.25 to about 30 inches in diameter, desirably from about 0.50 to about 12 inches in diameter and preferably from about 1 to about 4 inches in diameter.
Yet another object of the present invention includes providing clamping elements of the present invention having recesses thereon to adapted to provide access to a pipe joint held or clamped within the recesses so that a large surface of the pipes can be welded without having to rotate the clamping device.
REFERENCES:
patent: 575685 (1897-01-01), Brockett
patent: 1344700 (1920-06-01), Loomis
patent: 2440820 (1948-05-01), Frank
patent: 2699190 (1955-01-01), Packer
patent: 3403901 (1968-10-01), Servadio
patent: 3596898 (1971-08-01), Hillburn
patent: 4074899 (1978-02-01), Hochstetler
patent: 4134578 (1979-01-01), Stanely
patent: 4363475 (1982-12-01), McCarty
patent: 4747588 (1988-05-01), Dillhoff
patent: 4850630 (1989-07-01), Davies
patent: 4962918 (1990-10-01), Yang
patent: 5090670 (1992-02-01), Yang
patent: 5135209 (1992-08-01), Penny
Nolfi Mario Michael
Nolfi Thomas Joseph
Orosz Stephen William
Advanced Pneumatics
Hudak & Shunk Co. L.P.A.
Watson Robert C.
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