Abstract:
Additional flexibility of positioning of a welding gun head relative to a smooth surfaced flexible hose is provided by a generally elongate swivel joint positioned between the hose and a bellows connector. The swivel joint comprises two parts which rotate relative to one another about the longitudinal axis of the joint.

Description:
FIELD OF INVENTION 
     The present invention relates to welding guns. 
     BACKGROUND TO THE INVENTION 
     Welding guns for application of a weld to a desired site generally are provided at the remote end of a conduit in which is located a continuous weld wire extending from a wire source and a power cable extending from a power source. Often such welding guns are of the vacuum type which permit undesirable fumes to be removed from the welding gun site through the conduit. 
     Traditionally this conduit has been of corrugated construction along the whole length thereof, but the structure has no support for the weld wire and power cable and can wear through to expose the electrical power cable. 
     In my U.S. Pat. No. 4,496,823, the disclosure of which is incorporated herein by reference, there is described a novel multipassage flexible smooth-surfaced conduit which overcomes the problems of the prior art. In some instances, however, the conduit of my U.S. Pat. No. 4,496,823 is not sufficiently flexible to permit the ideal maneuverability of the welding gun head to make welds, particularly in hard-to-get-at locations. 
     For this reason, I invented a bellows-like flexible connector to connect the smooth-surfaced conduit to the welding gun head to permit the welding gun to be turned about universally with respect to the conduit. That structure forms the subject of my U.S. patent application Ser. No. 307,921 filed Feb. 9, 1989, the disclosure of which is incorporated herein by reference. 
     SUMMARY OF INVENTION 
     In accordance with the present invention, a further degree of flexibility is provided to the welding gun by providing a swivel joint between the downstream end of the conduit and the upstream end of the bellows-like connector, to permit rotation of the bellows about the longitudinal axis of the conduit. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a schematic representation of a fume-extracting welding apparatus into which can be incorporated a swivel joint in accordance with one embodiment of the invention; 
     FIG. 2 is a perspective view of a swivel joint element provided in accordance with one aspect of the present invention; 
     FIG. 3 is a perspective view of the joint of FIG. 2 located joining a bellows-like connector and a smooth-surfaced conduit; and 
     FIG. 4 is a sectional view of the arrangement of FIG. 3. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring to the drawings, FIG. 1 illustrates schematically a fume-extracting welding gun 10 including a head portion 12, a control handle portion 14 gripped by a welder 16 during operation, a flexible connector hose portion 18 and a services supply portion 21. The connector hose 18 preferably is constructed as described in my aforementioned U.S. Pat. No. 4,496,823. The welding gun head 12 may be constructed as described in my U.S. Pat. No. 4,727,238, the disclosure of which is incorporated herein by reference, or as described in my copending U.S. patent application Ser. No. 434,275 filed 11/13/89 (&#34;Nozzle&#34;), the disclosure of which is incorporated herein by reference. 
     The hose 18 is connected to the welding gun head 12 by a bellows connector 20, which may be constructed as described in my aforementioned U.S. patent application Ser. No. 307,921. 
     Turning now to FIGS. 2 to 4, the invention herein resides in the placing of a swivel joint 22 between the downstream end of the hose 18 and the upstream end of the bellows connector 20. The swivel joint 22 comprises two parts 24 and 26 which are both of generally cylindrical shape and which are positioned relative to one another to permit relative rotation about the axis of the swivel joint 22. The two parts 24 and 26 often are formed of different metals. 
     The first part 24 is provided with an outside diameter corresponding to the inside diameter of a tubular extension 28 of the bellows connector 20, so as to be received in sliding fit therein and to be clamped in immovable relationship by an outer clamp 30. 
     The first part 24 has a cylindrical shape for most of its length and has an inwardly-flared or frustoconical portion 32, which terminates at an inner diameter and an outwardly-flared portion 33 at the other end, which terminates at a second outside diameter. 
     The second part 26 is provided with an outside diameter corresponding to the inside diameter of the hose 18, so as to receive the hose in sliding fit therein and to be clamped in immovable relationship by an outer clamped 34. 
     The second part 26 has a cylindrical shape for most of its length and has an outwardly-flared or frustoconical portion 36 at the end opposite to that joined to the hose 18, which terminates in a second outside diameter. The inside diameter of the downstream end of the inwardly-flared portion 32 corresponds to the first outside diameter of part 26 while the outer diameter of the downstream end of the outwardly-flared portion 36 corresponds to the second outside diameter, so that the surfaces bear against each other to provide the rotational motion. 
     The bellows connector 20 comprises a plurality of individual bellow elements 38 which are integrally joined to each other so as to be resiliently flexible and permit universal movement of the welding gun head 12. To prevent inadvertent crushing and collapse of the bellows connector 20 in use, such as may occur when the welding gun is gripped at the bellows connector 20, a series of resilient rings 40 may be provided spaced apart substantially equally along the length of the bellows connector. When employed, the rings are located in the apices of individual ones of the bellows elements 38. 
     The bellows connector 20 and the swivel joint 22 combine to provide a considerable degree of flexibility for the operation of the welding gun 10 to position the welding gun head 12 at any desired orientation with respect to the hose. 
     SUMMARY OF DISCLOSURE 
     In summary of this disclosure, the present invention provides a novel structure in the form of a swivel which permits greater flexibility of position of a welding gun head by an operator. Modifications are possible within the scope of this invention.