CA1044766A - Arc welding torch having a flexible wire guide assembly - Google Patents

Abstract

ARC WELDING TORCH HAVING A FLEXIBLE
WIRE GUIDE ASSEMBLY

ABSTRACT

The flexible wire guide assembly of the torch is located between the torch body and the nozzle assembly and includes at least two layers of helically wound multi-strand conductor circumferentially arranged in concentric relation to form an annular passageway for a moving electrode. The layers are contained within an inner and outer extension spring which cooperate during the application of a bending force to restrain the layers from bulging inwardly or outwardly respectively. The outer spring is held in lateral compression with its turns spaced a predetermined distance apart.

Description

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Thls invention relates to gas shlelded metal arc torches through which a consumable electrode is driven under the control of a welding operator.

BACKGROUND

In certain lnstances the welding operator is confronted with limited access to the weld location re-qulring the operator to awkwardly positlon the torch in order to per~orm the welding operation. An obvious 901u~
tion to this problem would be to use a flexible guide whlch ls manipulatable into any position for guiding the direction Or the electrode wire through the nozzle of the welding torch where current is supplied to the elec-trode before it contacts the weld ~oint. A flexible ex-tension for use in con~unction with a nonconsumable weld-ing electrode gas shielded arc torch is shown and described in U.S. Patent No. 3,158,730 which iesued on November 24, 1964 to C.W. Hlll and entitled Gas Shielded Arc Torch.
The flexible assembly described therein consists of a bundle o~ elongated flexible solld metal wires which extend in a spiral con~iguration between the torch body and the nozzle. The bundle of wires provlde flexib~llty as well as perform the functlon of transmitting cur-rent from the torch bod~ to the nonconsumable elec-" . . .
~ trode located wlthin the nozzle. The sp~cification ~
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teaches how to corre~ate the number o~ strands and -~
slze of flexible wires needed to achieve a high degree ~, of rlgidlty at any chosen anguIar position with desir-able life and weight characteristlcs. This teaching .

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' ~ ''' can be directly employed ln the design of a ga~ shielded consumable electrode arc torch by using the flexible neck region of the torch as a conduit to provide passage ~or a movable electrode as well to provide control over its direction. A straight forward design would simply involve arranging the bundle of strands of wire around a cylindrical , sleeve innerliner which would form an annular passageway ,, for the electrode. Such a design would notJ howeverg ade-quately account for any tendency of the multiple strands ,, ,'~
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of wire and innerliner to kink or crimp durlng bending of ,,~
the flexible nec~. ~he ef~ect of such kinking or crimping would be to greatly increase the feed forces requ~red to '' drive the electrode through the torch body.

One de~ign directed specifically to a consumable electrode flexlble wire guide attachment for a gas shielded torch and which $s intended ko min,imize the tendency of the wire guide to kink during bending is shown and des-.
cribed in U.S. Patent No. 3~755,648 issued on August 28, 1973 and entitled Flexible Welding Nozzle Apparatus. The patent describes a ~lexible wire guide consisting o~ a ,' twisted bundle of wlre strands arranged about a steel sprlng ~, which forms the bore through which khe electrode passes.
The wire strands are constralned by an outer glass tape ' ~' support sleeve.' The tape sleeve ls lntended to prevent ;~

the coiled strands from spreading during bending whereas -' the spring liner is intended to apply a radlally outward force to maintain khe circularlty of the bore. Apparently whatever benefit is derlved from khe constraint placed on . . .: , .
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the windlngs comes only at the expense of flexibility in manipulating the wire guide attachment. The greater the constraint the less flexible the guide becomes and the greater the increase in spring back from a bent position.

SUMMARY OF THE INVENTION

The present invention is an improvement over the design in the aforementioned U.S. Patent No. 3,755,648, taklng advantage o~ the teachings in the earlier described U.S. Patent No. 3J 158,730 to provide a torch w~th a readily rlexible wire guide assembly capable of universal angular and lateral disposit:Lon but without experiencing kinklng or crimping in a bent position.
The metal inert gas shielded arc torch o~ the present invention in its broadest aspect comprises a body through which a consumable electrode is dr1venJ a nozzle assembly having means in electrical contact with the elec-trode and an elongated flexible wire guide assembly of predetermined length extending ~rom said body to said nozzle assembly for controlling the direction of the moving electrode through the nozzle; the wire guide assembly comprising:
at least two layers of solid metal wire .. . ..
each consisting of a multiple number of strands of wire secured at the ends thereor to said body and said nozzle assembly respectivelyJ said layers o~ wire being circum-- rerent1ally arranged in concentric relation for rorming an annular passageway with at least one o~ sald layers having a helical geometFy;

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means for restraining said layer~ of solid metal wire including a ~irst support spring dlsposed .`:~
wlthin said annular passageway abutting said layers of wire wlth its turns spaced close together, a second . ........ ..
support spring surrounding said layers of wire and means for malntaining said second support spring in compression ~:
with a spacing between turns equal to 10-25~ of the sprlng wire diameter so that sald layers of wire upon the appli-cation of a bending force will tend to slide relative to one another to ~orm a continuous curve with a given mini-mum radius of curvature; and a ~lexible insulating outer Jacket enclos-ing said layers Or solid metal wire and said fir~t and second ~upport spFing.

OBJECTS , .

Accordingly, it is the main ob~ect of the pres- .
ent invention to provide a metal arc gas weldlng torch .. , having a readlly ~lexible wire gui.de assembly capable of universal ad~ustment without kinking and flattening during bending.
Other ob~ects and advantages will become appar- :
ent from the followlng descriptlon when read ln connection wlth the accompanying drawings in which:
Figure 1 is an exterior view of a gas metal arc .:~ ;
., ~ . .weldlng torch illustrating the movable angular positions : .
of the ~lexible neck wire gulde assembly of the present ~.:
invention; ~;

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Figure 2 is a side view in longitudinal section of the torch and wire guide assembly of Figure 1 with the guide assembly broken to illustrate l~s internal parts;
and Flgure 3 is an elevation taken along the lines A-A in Figure 2.

DESCRIPTION OF TH INVENTION

The torch shown in Figures 1 to 3 inclusive com-prises a body 10, a flexible wire guide assembly 12 and a nozzle assembly 14. The torch body 10 is o~ conventional construction housing a pow0r cable 16 adapted ror connec-tlon to a power supply (not shown), a gas supply conduit 18 adapted for connection to a remote gas supply and a wlre ~eedconduit 20. A consumable electrode welding wire E is fed through the wire ~eed condult 20 from a remotely located ~pool o~ such wire (not shown). A switch handle 17, under the manual control of the welding operator triggers the supply o~ gas, activate~ power and advances the electrode E. The electrode E passes through the torch body 10, the ~lexible wire guide as~embly 12 and then through the nozzle assembly 14 ~rom whence it exits the torch. The elongated flexible wire guide assembly 12 is detachable ~rom the torch body 10 and ~rom the nozzle assem-bly 1l~ respectively. The torch wire guide 12 as illus- -trated in Figure 1 may be ~lexed rrom a horizontal attitude ~-a ~ull 180 degrees or more and in any angular direction.
The wire guide assembly 12 as will be explained in more :,: '' ' ' .
.. ' ~3~ ~7 le~ail hereafter is constructed so that upon the applica-tlon of a bendlng force it will form a continuous curve from the body 10 to the nozzle assembly 14 without kinking or flattening. This is essential since the electrode E
has llttle column strength and any obstructlon ln its path wlll prevent its passage. It is also an essential characterlstic that once the guide assembly 12 is bent, - it retain the bent configuration upon release of the bending force.
The detailed construction of the flexible wire guide assembly 12 is shown in ~lgures 2 and 3 and com-prises at least a first and second layer o~` conductor 20 and 22 each extendin~ from the torch body lO to the nozzle assembly 14. Each layer of conductor 20 and 22 consists o~ a predetermined number of electrically conductive ~~;
' strands of flexible solid metal wire preferably of copper ; and o~ a predetermined wire size. The selection of the wire size and the number of strands of wire is inter-related and based upon meeting the mechanlcal character-istics of flexiblllty and rigidlty and the electrical re qulrement that the combined layers have the proper current carrying capacity.
The inner layer of conductor 20 is spirally wrapped about a mandrel which is later removed to form the annular passageway 25. The direct~on of the spiral wind is unimportant although it is preferred that the outer layer 22 which surrounds the inner layer 20 also be helicallywound and in a direction opposite to the ~', .
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direction of wind of the inner layer 20. The oy~osite ends of each layer 20 and 22 are positioned within an annular s~ace 24 and 26 located in the end ~ittin~s 28 and 30 respectively. The layers are then secured by crimping the end fittlngs at 32 and 34. The end fitting 28 connects the flexible wire guide assembly 12 to the nozzle assembly 14 whereas the end fitting 30 connects the flexlble wire guide assembly 12 to the torch body 10.
A coiled steel extension spring 36, havlng its turns spaced close together, pre~erably with the turns ln con-tact~ is di~posed within the annular passageway 25. The spring 36 is Or a dlameter so that it f`its snugly within the passageway 25 and is of a length approximately equal to the distance L between the crimped ends of end fittings 28 and 30. An outer coil steel spring 38 surrounds the layers of winding 20 and 22 and has a predetermined spac~ng S between its turns wlthin a range of between 10-25~ of the spring wire diameter. The spacing S shown ln Figure 2 is exàggerated for clarity and ease of illustratlon. The preferred technique to achieve the desired spaclng S between the turn of sprlng 38 is to u~e a tightly wound extension spring, slmilar ln type to spring 36, cutting it to a length equal to 10-25%
less than length L and then stretching it into a free , length which ls greater than length L. The stretched spring 38 ls then mounted over the layers of wlndlng ~ ;
and laterally compres3ed before one of the end flttings 28 or 30 i~ attached. Therea~ter the end fittings 28 and 30 ma1ntain khe spring in a state o~ co~presslon.

The d$ameter o~ the spring 38 ~hould be sized to fik snugly about the outer layer of conductor 22. Although the inner and outer springs 36 and 38 are intended to abut the inner and outer layers 20 and 22 respectively,-the sprlngs need ':
not, and preferably do not, apply any radial force against .. ..... .
the layer~ ~or so lon~ as the flexible wire guide assembly 12 is in the horizontal or unbent position. A third spring 40, prererably a ~lat wlre spring, serves as the conduit for the electrode wire E. Although, the flat wire spring 40 need only extend for a distance equal to khe length L -of the wire guide assernbly 12 it is highly pre~erred that the wlre ~pring conduit 40 form a continuous liner extend-ing back to the wire feed source through the wire ~eed con-duit 20 as well a5 ~orward to within the nozzle asselnbly 14 up to the contact tip 42. A single llner provides con-tinuity for the moving electrode E and reduces the friction-. - .
al forces that would otherwise be developed by a transltion from one liner to another. The wlre guide assembly 12 is completed by enclosing the ~lexlble layers of conductor 20 and 22 and the sprlngs wlthin a tubular ~acket 44 o~ in-sulating materlal such as rubber and ra~tening the Jacket 44 at both endq of the a~sembly to the end fittings 28 and 30.
During operatio~, power is conducted through the power cable 16 in a conventional manner into one end~
of the conductlve end fitting 30 from where lt passes through to the layers of conductor 20 and 22 re3pectively.
The layer~ of conductor 20 and 22 in turn conduck power to ~` the opposite end fittlng 28 ~rom where power is further . . .
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transferred to the contact tip 42 of the nozzle assembly 14. Shielding gas is delivered from the supply conduit 18 through the torch body 10 w~ereupon lt is fed through the annular passage 48 of the end fitting 30 into the annular space 26 traveling down the flexible wire guide assembly 12 through the intertices formed between the layer~ of conductor 20 and 22 and through the clearance ~paces between suoh layers and the outer ~acket 44. Upon reaching end fittlng 28 the gas passes out from the annular space 24 into the nozzle assembly 14.
The position of the wlre guide assembly 12 1 ~anually ad3ustable from a horizontal position to an in-clined or angular positlon by moving the nozzle a~sembly 14 relative to the torch body 10. Upon the appllca~ion of a bending force the inner spring 36J having its turns ln close contact, provldes a uniform restraining force supportlng the layers of winding 20 and 22 from bulglng inwardly whereas the outer spring 38 tend~ to compress the layers 20 and 22 together and tends to restrain the layers 20 and 22 from bulging outwardly. The effect is to tightly sandwlch the first and second layer~ o~ con-ductor 20 and 22 against one another so as to increase the sllding friction between the layers. The increased ; -friction increases the resistance to further bending;
increases the rigidity of the wire guide assembly 12 and reduces any tendency of the wire guide assembly 12 .

- to springback. By using two or more layers of conductor 20 and 22 the rigidity of the wire guide assembly 12 is ' ~' .
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rendered dependent upon friction and not plastic deforma-tion as would be the case with only one layer of' conductor.
It is also preferred as mentioned earlier to oppositely wind the layers 20 and 22 which increases the resistance to fatigue and provides ~reater torsional resistance.
The outer spring 38 is held ln compression to prevent axial shifting of the spring durlng bending. It also assures a uniform restraining force upon the layers Or con-ductor over the Length L of the wire guide assembly 12.
A 250 amp torch for use with .045 wire was de-slgned followlng the principals Or the present inventlon u~ing a total of 38 strands Or solld copper wire conduc-tor Or .051 inch dlameter for the two layers Or conductor 20 and 22 respectively with the lnner conductor 20 wound wlth 16 strands Or wire and the outer conductor 22 wound with 22 strand~ Or wire. A length L Or five inches was u~ed with the wire guide a~sembly 12 designed for a minimum ~ bend radlus of one and a half lnches.
- It is to be understood that modirications and variations in deslgn parameter are wlthin the scope the present lnvention as defined in the appended clalms.

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Claims (6)

1. A metal inert gas shielded arc welding torch comprising; a body through which a consumable electrode is driven, a nozzle assembly having means in electrical con-tact with said moving electrode and an elongated flexible wire guide assembly of predetermined length extending from said body to said nozzle assembly for controlling the direction of said moving electrode through said nozzle, said wire guide assembly comprising:
at least two layers of solid metal wire each consisting of a multiple number of strands of wire secured at the ends thereof to said body and said nozzle assembly respectively, said layers of wire being circumferentially arranged in concentric relation for forming an annular passageway with at least one of said layers having a helical geometry;
means for restraining said layers of solid metal wire including a first support spring disposed within said annular passageway abutting said layers of wire with its turns spaced close together, a second support spring surrounding said layers of wire and held in compression with its turns spaced a predetermined distance apart so that said layers upon the application of a bending force will tend to slide relative to one another and form a con-tinuous curve with a given minimum radius of curvature; and a flexible insulating outer jacket en-closing said layers of solid metal wire and said first and second support spring.

2. A torch as defined in claim 1 wherein said predetermined spacing between the turns of said second spring is equal to a distance within the range of 10-25%
of the spring wire diameter.

3. A torch as defined in claim 2 further com-prising a third spring which extends at least through the full length of the torch body and through the wire guide assembly to within the nozzle assembly for providing a continuous inner lining for said moving electrode.

4. A torch as defined in claim 3 wherein each of said layers of solid metal wire are helically wrapped in opposing directions to one another.

5. A torch as defined in claim 4 wherein said second support spring is held in compression by means which also serves to secure said layers of conductor at its opposite ends thereof between said body and said nozzle assembly.

6. A torch as defined in claim 5 wherein said flexible insulating outer jacket is composed of rubber.