Apparatus for welding

Electric heating – Metal heating – For deposition welding

Reexamination Certificate

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Details

C219S125110

Reexamination Certificate

active

06653589

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to Australian Application No. PQ9331, filed Aug. 10, 2000.
FIELD OF THE INVENTION
The present invention relates to an apparatus for achieving weld build up. More particularly, the present invention provides an apparatus for achieving weld build up on the surface of a bore.
DESCRIPTION OF THE PRIOR ART
Many pieces of apparatus include one or more bores. Such bores may receive shafts or pins to thereby connect other apparatus via the bore. For example, earthmoving excavators have various buckets or blades attached thereto via pins that pass through bores formed in eyelet extensions connected to the buckets or blades.
With use, bores can become worn and lose their required dimensional tolerance. In the example of buckets and blades used on earthmoving equipment, this causes clearance and subsequent loose fit; which is unacceptable. To restore worn bores, it is common to apply a layer of weld metal to the bore. This layer of weld metal is then machined to attain a smooth finish and the required dimensions within the bore.
In order to improve the quality of weld build up in bores, automated bore welding equipment has been developed Such bore welding equipment typically comprises a welding head mounted to the end of a rotatable shaft. The rotatable shaft is rotated by a drive means. An axial drive means moves the rotatable head along the axial extent of the bore. The axial drive means may operate continuously, in which case a helical bead of weld metal is deposited in the bore. Alternatively, the axial drive means may operate only when a full diameter of weld metal is deposited in the bore such that adjacent diameters of weld metal are deposited in the bore.
An example of a bore welding apparatus is described in U.S. Pat. Nos. 4 687 899 and U.S. Pat. No. 4 873 419, both in the name of Acheson. The bore welding apparatus described in these patents comprises a hollow, rotatable drive spindle that carries an electrical welding torch at one end thereof. The welding torch terminates in a nozzle. The drive spindle is arranged to feed electrical current, welding wire and protective gas to the welding torch.
In order to provide rotating rotating to the drive spindle whilst allowing the electrical current, welding wire and protective gas to be supplied to the welding torch, the apparatus is provided with a power coupling that has a first housing and a second housing. The first housing is connected to the drive spindle and rotates with the drive spindle. The second housing is fixed against rotation by a torque resistant means. A first washer is soldered to the first housing and a second washer is soldered to the second housing. A spring and thrust bearing arrangement forces the housings toward each other and keeps the first washer in contact with the second washer The second housing is also slipped over a stem of the first housing. Axial movement of the welding torch is achieved by a rack and pinion type arrangement in which a rack on a quill is driven by a pinion wheel that rotates under the action of a worm gear driven by a worm rod. The worm rod is rotated by a separate drive motor.
The welding apparatus is mounted to a cantilever-type mounting arrangement. This mounting arrangement can be attached to the work piece by a magnetic head or by mechanical clamping means. In practice, it has been found that it is difficult to accurately align and maintain the position of the bore welding apparatus using that mounting arrangement.
Another bore welding apparatus is described in Australian patent no 717802 in the name of Russo. The apparatus described in this patent can perform the boring of holes or the surfacing of welding in holes. The apparatus comprises an external hollow shaft (called the “cool carrying shaft”). When used as a bore welding machine, a welding torch is carried on the end of the shaft. The tool carrying shaft has a projecting key along its length and this key engages with a key way formed inside a tubular motor hub that is located at the forward end of a tubular box. The tubular motor hub has a ring gear mounted on its external surface and this ring gear engages with the gear mechanism of an electric motor to thereby cause rotation of the motor hub As the tool carrying shaft is keyed to the motor hub, the tool carrying shaft also rotates with the motor hub.
The bore welding machine also includes a further electric motor that drives a gear that engages with a rack formed on an external shaft. This external shaft is coupled by two internal shafts to the tool carrying shaft. The rack and gear mechanism is used to cause longitudinal movement of the external shaft, and hence longitudinal movement of the tool carrying shaft with respect to the bore being repaired.
When used as a welding machine, the machine is mounted to the work piece. An auxiliary shaft is required to be mounted to the work pieces which auxiliary shaft hooks to the tool carrying shaft to thereby center the tool carrying shaft. The mounting arrangement of the machine described in Australian patent number 717802 fixes the position of the motor hub with respect to the work piece. Consequently, the tool carrying shaft must have the key that engages with the key way in the motor hub to enable the tool carrying shaft to move longitudinally through the motor hub during axial movement of the tool carrying shaft.
BRIEF DESCRIPTION OF THE INVENTION
In a first aspect, the present invention provides an apparatus for achieving build up of a weld metal inside a bore comprising a torch tube carrying a welding torch, said welding torch being positioned intermediate the ends of the torch tube, said torch tube being adapted to be mounted to a work piece by mounting means, rotating drive means for rotating the torch tube and axial positioning means for moving the torch tube in an axial direction relative to the bore.
As used through out this specification, the term “rotating drive means” is used to refer to a drive means that causes rotation of the torch tubes.
In an embodiment of the present invention, the torch tube is connected to a coupler means, said coupler means having a fixed portion and a rotatable portion. The coupler means provides a suitable coupler for coupling a welding apparatus to the torch tube. The coupler means may have a welding apparatus connection on the fixed portion thereof for connecting to a welding apparatus, such as a conventional MIG welding apparatus. The coupler means and the torch tube provide a suitable assembly for conveying electrical current, welding wire and/or protective gas to the welding torch.
The apparatus of the present invention preferably further comprises fixing means for selectively fixing the relative axial position of the torch tube in the apparatus. The fixing means may be selectively operable between a fixed position in which the relative axial position of the torch tube is fixed and a disengaged position in which the relative axial position of the torch tube in the apparatus can be altered. The fixing means most preferably can be selectively connected to and disconnected from the torch tube. The fixing means suitably comprises clamping means for clamping onto the torch tube.
The apparatus may further comprise connecting means for operably connecting the rotating drive means to the torch tube.
The connecting means may connect the rotatable portion of the coupler means to rotating drive means. However, the connecting means used in the present invention most suitably connects the rotating drive means to the torch tube by a pulley and drive belt arrangement or by a geared arrangement.
The rotating drive means may suitably comprise a drive motor that causes rotation of a first gear or pulley, said rotation of the first gear or pulley causing rotation of a second gear or pulley to thereby cause rotation of the torch tube. Preferably, the second gear or pulley is mounted to or formed on the fixing means to thereby cause rotation of the fixing means when the fixing means is connected to the torch tube. More preferably,

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