Electric heating – Metal heating – By arc
Reexamination Certificate
2002-01-24
2003-09-16
Paschall, Mark (Department: 3742)
Electric heating
Metal heating
By arc
C219S121480, C219S121510, C219S075000, C219S121470
Reexamination Certificate
active
06621038
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a torch for powder plasma buildup welding, and more particularly to a powder plasma buildup welding torch wherein a torch head is inserted into a pipe material to be subjected to buildup welding, to thereby carry out the welding on an inner peripheral surface of the pipe material.
A typical torch for powder plasma buildup welding which has been conventionally known or practiced in the art includes a torch head and a torch body for connecting a body of a welding machine such as a power supply or the like and the torch head to each other therethrough and is adapted to carry out buildup welding on an inner peripheral surface of a pipe material. Such a welding equipment is constructed so as to rotate the pipe material while keeping the torch head and a part of the torch body inserted into the pipe material and move the torch head in the pipe material to form a spiral padding on the inner peripheral surface of the pipe material, to thereby attain buildup welding on the pipe material. Such a torch for powder plasma buildup welding is used to carry out buildup welding on an inner surface of a pipe material for a petroleum reaction pipe, an injection molding cylinder or the like using a welding material which has corrosion resistance and wear resistance.
Unfortunately, the conventional powder plasma buildup welding torch must be varied in construction depending on dimensions of a pipe material, a configuration thereof and the like, resulting in handling thereof being troublesome. In a powder plasma buildup welding torch, the torch body is formed of a rigid material, to thereby fail to construct the whole torch in a compact manner, so that transport of the torch is troublesome. This renders repairing of the torch head highly hard when any failure or trouble occurs in the torch head.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a torch for powder plasma buildup welding which is capable of being readily handled irrespective of dimensions of a pipe material, a configuration thereof and the like.
It is another object of the present invention to provide a torch for powder plasma buildup welding which is capable of facilitating repairing of a torch head when it fails or breaks down.
It is a further object of the present invention to provide a torch for powder plasma buildup welding which is capable of restraining a variation in distance between an opening of a convergent nozzle of a torch head and an inner peripheral surface of a pipe material to be subjected to welding, to thereby form a padding uniform in size thereon.
It is still another object of the present invention to provide a torch for powder plasma buildup welding which is capable of preventing leaping of a torch body.
In accordance with the present invention, a torch for powder plasma buildup welding is provided. The torch includes a torch head adapted to be inserted into a pipe material of a continuous length to carry out buildup welding on an inner peripheral surface of the pipe materiall and a torch body formed into a continuous length and having the torch head mounted on a distal end thereof. The torch head is replaceably connected to the torch body. Such construction permits buildup welding to be attained in conformity to any size of a pipe material to be subjected to welding, any configuration thereof and the like. Thus, the present invention facilitates application of the torch to welding while eliminating replacement of the whole powder plasma buildup welding torch required in the prior art. Also, when any failure or trouble occurs in the torch head, the torch head may be readily repaired because it is detached from the torch body.
In general, the torch head includes a convergent nozzle having an opening. In a preferred embodiment of the present invention, either torch head or torch body is provided with a gap formation spacer member which is abutted against the inner peripheral surface of the pipe material to keep a distance between the opening of the convergent nozzle of the torch head and the inner peripheral surface of the pipe material substantially constant when welding takes place. Such arrangement of the gap formation spacer member in the torch effectively prevents a variation in distance between the opening of the convergent nozzle of the torch head and the inner peripheral surface of the pipe material subjected to welding due to a weight of the torch head and/or deflection of the torch body, to thereby ensure formation of a padding of a uniform size on the inner peripheral surface of the pipe material.
An increase in length of the torch body tends to cause it to be deflected in the pipe material during buildup welding. In particular, arrangement of the gap formation spacer member causes leaping of the torch body during rotation of the pipe material depending on abutment between the gap formation spacer member and the inner peripheral surface of the pipe material, leading to an increase in deflection of the torch body. In view of such a disadvantage, the torch body is preferably provided with at least one deflection restraint spacer member adapted to be abutted against the inner peripheral surface of the pipe material so as to prevent deflection of the torch body in the pipe material during buildup welding.
More specifically, in accordance with the present invention, a following torch for powder plasma buildup welding is provided. The torch includes a torch head adapted to be inserted into a pipe material of a continuous length to carry out buildup welding on an inner peripheral surface of the pipe material and a torch body formed into a continuous length and having the torch head mounted on a distal end thereof. The torch body includes a connection pipe and a plurality of pipes arranged in said connection pipe. The plurality of pipes feed cooling water, gas and the like to said torch head, respectively. The plurality of pipes include two or more pipes made of an electrically conductive material. One of the two or more pipes constitutes a first conductive portion electrically connected to one of electric poles of a DC power supply and another of the two or more pipes constitutes a second conductive portion electrically connected to the other of said electric poles. The torch head includes a bar-like electrode, an electrode support made of an electrically conductive material and arranged for supporting the bar-like electrode, a convergent nozzle made of an electrically conductive material, a nozzle support made of an electrically conductive material and arranged for supporting said convergent nozzle, and a head-side insulation member arranged between the electrode support and the nozzle support to electrically insulate the electrode support and nozzle support from each other. The head-side insulation member includes a projection portion projecting beyond the electrode support and nozzle support and toward the torch body. The connection pipe of the torch body is fixedly provided on an end thereof defined on a side of the torch head with an insulation flange. The insulation flange is attached with a connection member. The connection member includes a first connection member half and a second connection member half which are arranged so as to be spaced from each other through a cavity defined therebetween and fitted with the projection portion. One of the two or more pipes mentioned above is connected with the first connection member half through the insulating flange. Another of the two or more pipes mentioned above is connected with the second connection member half through the insulating flange. The electrode support is contacted with the first connection member half. The nozzle support is contacted with the second connection member half. The torch head is replaceably connected to the torch body by means of a plurality of bolts for fixing the torch head and connection member to each other.
The torch of the present invention th
Imai Minoru
Onitsuka Yoshimi
Nippon Welding Rod Co., Ltd.
Paschall Mark
Pearne & Gordon LLP
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