Work holders – Magnetic holder
Reexamination Certificate
2000-09-08
2001-08-28
Morgan, Eileen P. (Department: 3723)
Work holders
Magnetic holder
C269S2540CS, C269S006000, C269S239000, C269S268000, C269S901000, C269S902000
Reexamination Certificate
active
06279885
ABSTRACT:
TECHNICAL FIELD
The present invention pertains generally to welding, and in particular to a magnetic welding clamp that is attached to magnetic objects to provide a ground during arc welding.
BACKGROUND ART
When arc welding, it is necessary to attach a ground to the object being welded while the other pole of the electric circuit is the welding rod. When the electricity passes through the welding rod to the object, it melts the tip of the welding rod thereby depositing molten metal on the object.
Usually a spring clamp is used to connect the ground cable from the welding apparatus to the object. Nuts on the top of the clamps are used to attach the lug of the ground cable to the clamps. In one common embodiment, a spring loaded terminal (refer to
FIG. 3
) is attached to a flat magnetic clamp. The spring loaded terminal has a bolt that passes through the middle of the magnet and abuts the object to be welded. In this fashion, the electric current does not pass through the magnet, but rather is shunted directly through the bolt.
DISCLOSURE OF INVENTION
The present invention is directed to a magnetic clamp having two cooperating magnetic members for use in arc welding a magnetic workpiece object. The present invention is particularly useful when welding pipes since a single flat magnet does not stay on a pipe very well because the contact area is limited to a straight line allowing the single magnet to be twisted off. By having two magnets at an angle to each other, the holding power is increased and the clamp of the present invention cannot easily be twisted off of the pipe.
The two magnets can either be held rigidly at an angle to each other or hinged to each other. In the middle of the two magnets is a spring loaded terminal which attaches to a welding cable lug on the top and touches the pipe on the bottom. If the two magnets are rigidly at an angle to each other, a problem arises in that the length of the bolt into the “V” of the clamp must be adjusted to just touch the pipe. If it is too long, it will hold one side of the magnets off of the pipe. If it is too short, it will not make contact with the pipe. Each different pipe diameter requires the length of the terminal to be readjusted. A solution to this problem is to create a two sided magnetic clamp which has hinges in the middle, thereby permitting the clamp to automatically adjust to different pipe diameters and be used on flat objects. The two sides rotate around the hinge pin to match the diameters of various pipes with no adjustment of the bolt length being required to touch the pipe as in the rigid “V” shaped clamp.
In accordance with a preferred embodiment of the invention, a magnetic clamp for welding a magnetic object includes two flat magnetic members connected by a hinge so that the angle formed by the two magnetic members can be varied. A spring loaded terminal having a contact end is disposed between the two magnetic members, so that the clamp may be attached to a magnetic object with the first magnetic member, the second magnetic member, and the contact end all abutting the magnetic object.
In accordance with an important aspect of the invention, each of the two magnetic members have a substantially flat bottom surface, so that both bottom surfaces can be adjusted to abut a substantially flat magnetic object.
In accordance with an important feature of the invention, two hinges are utilized to connect the two magnetic members.
In accordance with another preferred embodiment of the invention, the magnetic clamp includes a removal tab for removing the magnetic clamp from the magnetic object.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
REFERENCES:
patent: 2884698 (1959-05-01), Wursch
patent: 5135206 (1992-08-01), Martinez
patent: 5201501 (1993-04-01), Fassier
patent: 5820116 (1998-10-01), Haese
patent: 5971379 (1999-10-01), Leon, Jr.
patent: 6092271 (2000-07-01), Stojkovic et al.
Freilich Hornbaker & Rosen
Masters Ted
Morgan Eileen P.
Tyson Timothy Thut
Wilson Lee
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