EP0020362A1

EP0020362A1 - Welding torch cooled by liquid-gas transition

Info

Publication number: EP0020362A1
Application number: EP79900942A
Authority: EP
Inventors: John G. Frantzreb, Sr.
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1978-12-07
Filing date: 1980-06-17
Publication date: 1981-01-07
Also published as: BR7808760A; EP0020362A4; WO1980001147A1; JPS55500933A

Abstract

Pendant le fonctionnement d'une torche de soudage (10), un fil electrode (17) se deplace a travers un assemblage a pointe de contact (14) directement dans une zone de soudage. L'assemblage (14) est expose a des temperatures elevees et les perles de soudure peuvent endommager et deteriorer l'assemblage (14). Dans la torche (10), un liquide est recu par un premier appareil (44) et se vaporise essentiellement en raison des temperatures de soudage elevees au niveau du premier appareil (44). Le but est de refroidir l'assemblage (44) et de resoudre les problemes de temperature. Dans une torche possedant un bec (18), le bec (18) dirige une partie du liquide vaporise sur la zone de soudage pour proteger l'operation de soudage. Dans un mode de realisation de la torche (10) equipee du bec (18), une pointe de contact (25) de l'assemblage a pointe de contact (14) est positionnee en contact avec le bec (18) pour tirer avantage du premier appareil (44) en vue de refroidir a la fois la pointe de contact (25) et le bec (18).During the operation of a welding torch (10), an electrode wire (17) travels through a contact tip assembly (14) directly into a welding area. The assembly (14) is exposed to high temperatures and the solder beads can damage and deteriorate the assembly (14). In the torch (10), a liquid is received by a first device (44) and vaporizes essentially due to the high welding temperatures at the first device (44). The goal is to cool the assembly (44) and solve temperature problems. In a torch having a nozzle (18), the nozzle (18) directs part of the liquid vaporized on the welding zone to protect the welding operation. In one embodiment of the torch (10) equipped with the nozzle (18), a contact tip (25) of the contact tip assembly (14) is positioned in contact with the nozzle (18) to take advantage of the first apparatus (44) for cooling both the contact tip (25) and the spout (18).

Description

WELDING TORCH COOLED BY LIQUID-GAS TRANSITION

Technical Field

The invention relates to welding torches. More particularly, the invention relates to cooling the welding torches.

Background Art

In the use of a welding torch, it is desirable to cool the torch as much as possible in order to sub- stantially prevent damage to said torch from the elevat¬ ed temperatures of the welding operation and from weld - spatter.

For example, in arc welding operations . involving the use of gas for shielding the arc area of the weld, the welding torch has a nozzle and a contact tip. During welding, wire passes through and is support¬ ed by the contact tip which is positioned directly adjacent the weld area. The nozzle directs gas supplied to the torch, such as carbon dioxide gas, into the weld area for shielding purposes. The gas is generally supplied from a supply tank through hoses to the torch. Said gas can also be supplied in liquid form to a location upstream of the torch where it is gasified before entering the torch. In the torch, the nozzle is connected to a body of the torch and the contact tip is connected to a central guide housing. Both the contact tip and guide housing are positioned inside the torch body and are insulated from the nozzle and torch body. Electrical current is passed through the central guide housing and contact tip to the electrode wire to provide the electrical potential between the wire and work piece necessary in arc welding operations. -2- ^'

The contact tip and nozzle_., positioned immediately adjacent the weld area, are directly expos¬ ed to the elevated temperatures of welding. During such operations , it is desirable to cool both.the 5 nozzle and the contact tip to prevent "burn through" owing to the high temperatures and to prevent build-up of weld spatter, which can result in frequent replace¬ ment of the nozzle or contact tip and interference with gas flow to the arc area. 0 Heretofore, the contact tip has been cooled by liquid, generally water, circulated through the guide housing adjacent the contact tip. The nozzle is air- cooled except for indirect cooling effects from the ■ guide body through the insulated area between the

15 nozzle and guide body. Such welding torch construction is disclosed in U.S. Patents 3,689,733 which issued to Mai^arovic on September 5, 1972, and 3,529,126 which issued to Reeh on September 15, 1970. Matarovic also uses the shielding gas supplied to the torch to cool

20 the outer or handle portion of the torch by directing the flow of gas through a portion of the torch associat ed with the handle.

Another type of welding involving problems of elevated temperature is that which does not require gas

25 for shielding purposes, such as in electro-slag welding. The welding torch does not, therefore, generally make use of a nozzle. The contact tip is connected directly to the body through a mounting assembly and the electri cal current passes through the body and contact tip to

30. the wire. Cooling of the contact tip and the mounting assembly is also important to prevent damage to the welding torch owing to problems similar to those dis¬ cussed above which are associated with the high temper¬ atures created in the welding process.

The cooling of the above described welding torches, particularly in a heavy duty cycle of automat¬ ed or robot welding, is sometimes not adequate. • It is therefore desirable to provide apparatus to more directly cool the contact tip and the associated mounting element or nozzle, where present.

It will be appreciated that the use of liquids, which absorb heat during gasification, in direct association with the nozzle or contact tip can provide cooling of said elements during the gasifi¬ cation process. This is particularly true in the use of such liquids as carbon dioxide which absorb a relatively high amount of heat energy during gasifi¬ cation. Thus, preferably, liquid is supplied into the welding torch and directly onto the nozzle, contact tip or elements closely associated thereto for gasification owing to the elevated temperatures of welding at said components of the torch.

In a preferred embodiment, the nozzle can be in direct contact with the contact tip, which can serve to improve heat transfer, and thus cooling, relative to liquid supplied at only one of said contact tip and nozzle. Advantageously, the size of the welding torches is reduced by eliminating the necessity of both liquid coolant inlet and outlets. In gas shielded welding, portions of the gasified liquid can also be directed to the weld area thus eliminating the need for. additional apparatus to also supply shielding gas to the welding torch.

Disclosure of Invention

In one aspect of the present invention, a welding torch has a body and a contact tip assembly associated with said body. First means is provided for receiving a flow of liquid and maintaining a flow of gas relative to the contact tip assembly in response to

OMPI

/,. WIPO gasification of the liquid at said first means. , Second means is provided for delivering liquid to said first means.

In another aspect of the present invention a welding torch has a body, a contact tip assembly and a -nozzle. The nozzle is connected to the body. The contact tip assembly has a contact tip positioned in direct contact with the nozzle.

During welding operations, the contact tip assembly, and the nozzle, if present, are exposed to the elevated temperature of welding which can cause adherence of weld spatter and increased deterioration of the welding torch. Gasification of the liquid at the first means acts to cool the contact tip assembly and substantially overcome the above mentioned problems Where present, the nozzle directs some of the gasified liquid toward the weld area to shield the welding operation. The nozzle is preferably positioned in contact with the contact tip in order to take further advantage of the cooling functions of the first means relative to both the nozzle and the contact tip.

Brief Description of Drawings

FIG. 1 is a diagrammatic cross-sectional view showing one embodiment of the present invention; FIG. 2. is a diagrammatic end view of FIG.- 1;

FIG. 3 is a diagrammatic cross-sectional view showing another embodiment of the present invention;

FIG. 4 is a diagrammatic cross-sectional view taken along lines IV-IV of FIG. 3; FIG. 5 is a partial diagrammatic cross- sectional view showing yet another embodiment of the present invention;

FIG. 6 is a partial diagrammatic cross- sectional view showing still another embodiment of the present invention; FIG. 7 is a partial diagrammatic cross- sectional view shewing still yet another embodiment of the present invention; and

FIG. 8 is a partial diagrammatic cross- sectional view showing yet one more embodiment of the present invention.

^' Best Mode for Carrying Out the Invention

Referring to the drawings, a welding torch 10 has a body 12, a contact tip assembly 14 and an elec- trόde pathway 16. The electrode pathway 16 passes through the body 12 'and the contact tip assembly 14. The contact- tip assembly 14 is associated with the body 12 and supports electrode wire 17, which passes through- the electrode pathway 16 during welding operations as is known in the art. A wall 15 defines one portion of the electrode pathway 16 and includes a- replaceable liner and a conduit guide as is also known in the ^' welding art. Each of the separate embodiments shown in the drawings is hereinafter more fully discussed with respect to the particular construction and operation of said embodiments.

Referring to the embodiment of FIG, 1, the welding torch 10 has a nozzle 18 having first and second end portions 20,22. Said nozzle 18 is connected ^• at the first end portion 20 to a first end portion 24 of the body 12. The contact tip assembly 14 includes a contact tip 25 having first and second end portions 26,28 and being associated with the nozzle 18 and the body 12. The electrode pathway 16 passes through the contact tip 25 and opens on the first end portion 26 of said contact tip 25 adjacent the second end portion 22 of the nozzle 18. Said embodiment is intended princi¬ pally for use in gas shielded, arc welding applications owing to the use of a nozzle which, by definition, include that portion of a welding torch directing gas for shielding purposes to the arc area of a weld during tfl OM use of the torch. The nozzle 18 of Fig. 1, for example- is of unitary construction with the body 12. Said nozzle 18 can also be removable or welded to the body 12, as is done in Fig. 3 with a mounting element to be 5 described herein. <.

The contact tip 25 of the welding torch 10 of FIG. 1 is positioned in direct contact with the nozzle 18-. It should be understood -that direct contact indicates that there is no substantial ba'rrier, such as

10 an electrical or heat insulating material or air gap, for example, between the nozzle 18 and contact tip 25 which can interfere with the transfer of hea_,t between said nozzle 18 and contact tip 25.- The nozzle 18 has an opening 30 having a surface 32. The second end

15 portion 28 of the contact tip 25 is positioned in said opening 30 and in contact with the surface 32 of said opening 30. The first end portion 26 of the contact tip 25 is positioned adjacent the second end portion 22 of the nozzle 18. The nozzle opening 18 and second end

20. portion 28 of the contact tip 25 preferably have mate- able tapering configurations as shown. The contact tip assembly 14 includes a set screw 33 which removably maintains the contact tip 25 in position. Said welding torch 10 includes a current pathway passing from an

25 input lead connecting bolt 34 at a second end portion 36 of body 12, through said body 12, and the nozzle 18 and to the contact tip 25 for providing electrical potential across the electrode wire 17 and a work piece (not shown), during welding operations. The tapering

30 surface to surface contact of the nozzle 18 and contact tip 25 provides a positive current pathway through the welding torch 10.

The embodiment of FIG. 8 shows another aspect of the present invention with respect to welding

35 torches of the gas shielding type and will be discussed hereinafter in more detail. The torch 10 has the

Tu elements as previously described with respect to the embodiment of FIG. 1. However, the nozzle 18 and body 12 are electrically insulated by a liner 35 and. an air gap 37 from the electrode pathway 16 and contact tip assembly 14 as is generally known in the art. Said electrical insulation also establishes a heat transfer barrier between the nozzle 18 and contact tip 25.

^•Referring to the embodiment of FIG. 3, the welding torch 10 is of the type intended principally for welding which does not require a gas shield, such as welding of the electro-slag type. • Said embodiment can also be used for arc welding without gas shielding. The contact tip^' assembly 14 includes the contact tip 25 as previously discussed and a mounting element 38. The contact tip 25 ^"is connected to the body 12 through- the mounting element 38. A current pathway through the torch .10 is thus established through the mounting element 38 and contact tip 25 similar to the torch 10 of FIG. 1. A connecting element 40, shown as, for example, a bolt 42 is positioned in engagement with the contact tip 25- to maintain it in position in the mount¬ ing element 38 in a manner similar to that discussed with reference to FIG. 1. As shown, FIG. 3 includes a pair of contact tips 25 and associated elements. Also, an insulating element 39, such as a ceramic coating, is positioned on an outer surface 41 of the welding torches 10 described herein, except for Fig. 8, in order to electrically isolate the torches 10 and pre¬ vent a short circuit between the torch 10 and a work piece (not shown) . Handles or similar apparatus can be added for manually operated torches.

In the welding torches 10, first means 44 is provided for receiving a flow of liquid and controllably maintaining a flow of gas to a- preselected location relative to the contact tip assembly 14 in response to gasification of said liquid at said first means 44.

.- wIiPrOυ Said first means 44 is associated with and positioned immediately adjacent the contact tip assembly 14. Second means 46 is provided for controllably delivering a preselected amount of liquid to said first means 44. 5 In the embodiment of FIG. 1, the first means 44 is positioned on one of the nozzle 18 and contact tip assembly 14 (FIGS. 1 and 6 and FIG. 5, .respectively) . In the embodiment of FIG. 3, the first means 44 is positioned on the contact tip assembly 14. Thus, said ιo first means 44 can be positioned on the mounting ele¬ ment 38, as is shown in FIG. 3, or on the contact tip 25 as shown in FIG. 7.

The first means -44 includes an expansion element 43. The one of the contact tip assembly 14 and

15 nozzle 18 having said first means 44 in a particular embodiment has a surface 50 defining said expansion element 48. For example, in FIG, 1 the nozzle 18 has the first means 44 and the second end portion 22 of said nozzle 18 has an opening 52 having sidewalls 54.

20. The surface 50 defining the expansion element 48 includes said sidewalls 54. In embodiments similar to FIG. 3, the surface 50 defining the expansion element 48 is positioned on one of the contact tip 25 and mounting element 38 as shown in FIGS. 7 and ^'3, respecti

25 vely. In FIG. 8, the contact tip assembly 14^' has the mounting element 38 having the surface 50 and connect¬ ing the contact tip 25 to a central insulated conduit 56. The surface 50 in said embodiments are of a con¬ figuration and defined in a manner similar to the

30 surface 50 discussed above with respect to FIG. 1. It should be understood that other configurations of the expansion element 48 can be used without departing from the invention.

The electrode pathway 16 can pass through the

35 expansion element 48 as shown in some of the embodiment The opening 52 can also have a bottom wall 58 with the

Λ, surface 50 defining the expansion element 48 including said.bottom wall 58 (FIGS. 5 ^"and 7). When the elec¬ trode pathway 16 does not pass through the expansion element 48, it is preferable to provide external access 5 through the expansion element 48 for cleaning purposes. Thus, as seen in FIG. 3, for example, the connecting element 40 has a surface 60 and is removably connected to the contact tip assembly 14. The surface 50 defin¬ ing the expansion element 48 includes said surface 60 0 of the connecting element 40. The welding torch 10 of the type shown in FIG. 1 can also be similarly con¬ structed by removably connecting the connecting element 40 to the nozzle 18 (FIG. 6).

The. second means 46 includes a tube 62, . 5 preferably of a capillary type, and an orifice 64 having a preselected configuration and being connected to or positioned on said tube 62. The orifice 64 is -spaced a preselected distance from the first means 44 or expansion element 48 which is determined by the 0 capability of the system to deliver the liquid as desired to the expansion element 48. Said orifice 64 is oriented sufficient for directing said liquid delivered to the expansion, element 48 to a preselected position at and onto said expansion element 48. Said 5 preselected- position is preferably located centrally on the surface 50, defining the expansion element 48, such as, for example, the surface 60 of the connecting element 40 (FIG. 3) . Liquid is delivered through the tube- 62 and orifice 64 onto the surface 50 defining the

30. expansion element 48 for purposes hereinafter discussed.

The welding torch 10 includes a gas flow pathway 66 in fluid^' communication with the first means 44 or expansion element 48. Said pathway 66 is. of a configuration sufficient for directing a flow of- gas

35 from said expansion element 48 to a location spaced from the contact tip assembly 14. As is shown, the

OMPI

/,, WIIPPOO body 12 has a central chamber 67 and the gas flow pathway 66 includes said chamber 67. The electrode pathway 16, tube 62 and orifice 64 are also positioned in said central chamber 67. The second end portion 36 of the body 12 has an opening 68 having a preselected configuration. The gas flow pathway 66 includes said opening 68. One embodiment of the opening- 68,- shown in detail in FIG. 4, is positioned in a head element 70 of the body 12. The opening 68 can also be of a con- figuration and orientation as shown in FIG. 1.

A second gas flow pathway 72 is also contain¬ ed in welding torches of the type described with respec to FIG. 1. Said gas flow pathway 72 is positioned in fluid communication with the first means 44 or expansio element 48 and with, the first end portion 26 of the contact tip 25. In the preferred embodiment,^' said gas flow pathway 72 includes a passageway 74 through the nozzle 18 and opening on the first and second end portions 26,28 of said nozzle 18. .The nozzle 18 has a plurality of passageways 74 as is best seen in Fig. 2, for example, to assure a flow of gas to surround the first end portion 26 of the contact tip 25. It should be understood that said gas flow pathways 66,72 can also be of other configurations and orientations, such as conduits externally fixed to the welding torch 10, without departing from the invention.

It should be understood that the configuratio of the welding torches herein described can be of other configurations without departing from the invention.

Industrial Applicability.

In the use of the welding torch 10, liquid under pressure passes through the orifice 64 onto the expansion element 48 and gasifies owing primarily to the elevated temperature during welding of the surface 50 defining the expansion element 48. The gasification

. resu.lts in cooling of the torch 10-and, in the case of a nozzle equipped torch 10, some gas is directed to the first end portion 26 of the contact tip 25 for shield¬ ing purposes. For example, operation of the welding torches described subjects the contact tip 25 and the nozzle 18 or mounting element 38 to extremely high temperatures owing to their close proximity to the weld location. Liquid is supplied in a hose 69 at the head element 70 and to the tube 62 for delivery to the orifice 64. The orifice 64 directs the liquid preferably in a steady stream onto the sur ace 50 defining the expansion element 48. The elevated temperature of the surface 50 tends to gasify the liquid upon contact. In the case of some types of liquids, such as carbon dioxide, for example, which is a preferred coolant, the instability of the liquid phase also tends to promote gasification. The resultant gasification cools the contact tip 25 and nozzle 18 or mounting element 38 substantially prevent- ing building of weld spatter and deterioration of the welding torch 10 at the high temperatures of welding. The nozzle 18 or mounting element 38 are preferably constructed of a highly conductive material, such as copper, to promote heat transfer for maximum cooling. The contact tip 14, however, is preferably of a material of high temperature hardness, such as tungsten carbide, to resist wear resulting from the passing of the elec¬ trode wire 17 therethrough.

The expansion element 48 controllably main- tains a flow of the gasified liquid generally upward from the contact tip 25 as a result of the liquid dropping onto the expansion element 48 and the sudden gasification at elevated temperatures. The gas.ified liquid or gas tends to^"pass through the central chamber 67 and opening .68 of the body 12 to the atmosphere (.shown by flow lines 76 in FIGS. 1, 3 and 4) . The

f OMPI

_{\ f} ^" WIPO configuration of the expansion element 48 also tends to promote gasification and the flow of gas by increasing surface area and controlling the gasification process. It is the inventor's opinion that as liquid is spilled centrally into the expansion element 48 as disclosed liquid and gasified portions of the liquid will move outwardly from the stream of liquid and upwardly adjacent the sidewalls 54 of the_, opening 52 toward the central chamber 67 of the body 12. Where gas shielding is desired, a back pressure of gas is created by the size or configuration of the vent opening 68 in order to induce a flow of gas through the passageways- 74 in the nozzle 18 and toward the first end portion 26 of the contact tip 25. Said gas flow is shown by flow lines 78- in FIGS. 1 and 8.

In other words, gas is metered from the central chamber 67 of the body 12 and to the atmosphere in order to establish sufficient back pressure in the chamber 67 to encourage flow through the nozzle passageways 74. The size of the passageways 74 also determine the amount of shielding gas available. Gas also tends to flow in the electrode pathway 16 adjacent the electrode wire 17 owing to the back pressure or to the action of the moving wire 17. This provides some blocking of air or contaminates entering into the welding torch 10 for more efficient torch operation. It will be readily apparent that the preselected amount of liquid deliver¬ ed by the second means 46, or through the tube 62 or orifice 64, will depend upon the amount of cooling necessary and the magnitude of the back pressure which limits the flow of the gas.

As will be understood from a study of draw¬ ings, the construction of the embodiments disclosed in FIGS. 1-7 is generally applicable one to the other with the exception of the use of a nozzle or mounting element for particular types of welding. The embodimen

O W ς>£ FIG. 3 can also be adapted to welding of the gas shielding type by removing one of the contact tips 25 or the electrode wire 17 to provide a passageway through the mounting element 38. It should also be appreciated that the embodiment of FIG. 8 will not make significant use of the cooling effect on the nozzle 18 owing to the isolation -of the nozzle 18 from contact tip assembly 14. Annular cooling passages in the torch 10, such as for water, are also eliminated in said embodiments owing to dual use of the liquid in some torches and delivery of the liquid directly onto the nozzle 18 and contact tip 25 area of the torch 10^'' for cooling purposes.

Other aspects, objects and advantages will become apparent from a study of the specification, drawings and appended claims.

vl! ._*\-ci

Claims

1. In a welding torch (10) having a body (12) , a contact tip assembly (14) and an electrode pathway (16) , said contact tip assembly (14) being associated with the body (12) , said electrode pathway

, 5 (.1.6) passing through said body (;12) and contact tip ^• assembly (14) , the improvement comprising: first means . (.44) for receiving a flow of liquid and controllably maintaining a flow of gas to a preselected location relative to said contact tip 10 assembly (.141 in response to gasification of said liquid at said first means (_.44) , said first means (.44). being associated with and positioned immediately adjacent said contact tip assembly (.14) ; and second means (46). for controllably deliverin 15 , a preselected amount of liquid to said first means (44) .

2. The welding torch (.101, as set forth in claim 1, including a nozzle (.181 connected to the body (12) and wherein the contact tip assembly (.141 is

20 positioned adjacent said nozzle C181.

3. The welding torch (.10) , as set forth in claim 2, wherein said first means (44) is positioned, o one of the contact tip assembly (.14)_. and the nozzle (_.18) .

25 4. The welding torch (10) , as set forth in claim 1, wherein the first means (44) is positioned on the contact tip assembly (14) .

O 5. The welding torch (10) ,- as set forth in claim 2, wherein said contact tip assembly (14) has a contact, tip (25) , said nozzle (18) and contact tip (25) each having an end portion- (22,26) and said electrode pathway (16) opens on the end portion (26) o the contact tip (25) adjacent said end portion (22) of the nozzle (18) and including a gas flow pathway (72) positioned in fluid communication with the first means (44) and with said end portion (26) of the contact tip (25).

6. The welding torch (10), as set forth in . claim 5, wherein said gas flow pathway (72). includes^'- a passageway (74) through the nozzle (18) .

7. The welding torch (10) , as se _*t forth in claim 3, wherein said first means (44) includes an • expansion element (48) and the one of said nozzle C18) and contact tip assembly (14) having said first means (44) has a surface (50) defining said expansion element (48).

8. The welding torch (.10) , as set forth in claim 7, wherein said nozzle £181 has the expansion element (48) , said second end portion (22) of the nozzle (18) has an opening (52). having sidewalls (.54) and the surface (50) defining said expansion element (48) includes said sidewalls (54) .

9. The welding torch (10), as set forth in claim 8, wherein said opening (.52). has a bottom wall (58) and said surface (50) defining the expansion element (.48) includes said- bottom wall (58) . 10. The welding torch (10), as set forth in claim 7, wherein the electrode pathway (16) passes through the expansion element (48) .

11. The welding torch (10) , as set forth in claim 4, wherein the first means (44) includes an expansion element (48) and said contact tip assembly (14) has a surface (50) defining said expansion elemen (48).

12. The welding torch (.10), as set forth in claim ll, wherein the contact tip assembly (.14) in¬ cludes a contact tip (25). and a mounting element (38) , said contact tip (25) being connected-to the body (12) through the mounting element (38) and said surface (.50) is positioned on one of said contact tip (25L and said mounting element (38) .

13. The welding torch (.10), as set forth in claim 12, wherein the one of the contact tip C.251 and the mounting element (.38) having the surface (.50) defining the expansion element (481 has an opening (.52) having sidewalls ^'(.54) and said surface (50). includes said sidewalls (.54) .

14. The welding torch (.10) , as set forth in claim 11, wherein the electrode pathway (.16). passes through the expansion element (.48) .

15. The welding torch (10), as set forth in claim 14, wherein the opening 52) has a bottom wall (58) and said surface (60). defining the expansion element (.48) includes said bottom wall (58) . 16. The welding torch (10) , as set forth in claim 11, including a connecting element (40) haying a surface (60) and being removably connected to said • contact tip assembly (14) and said surface (50) defin- ing the expansion element (48) includes said surface . (60) of the connecting element (40) .

17. The welding torch (10) , as set forth in claim 16, wherein said connecting element (40) is positioned in engagement with the contact tip (25) .

18. The welding torch (10) , as set forth in claim 8, including. a connecting element (40) having a surface (60) and being removably connected to said nozzle C18) and wherein said surface (.50) defining the expansion element (48)_. includes said surface (601 of the connecting element (.401.

19. The welding torch CIO) , as set forth in claim 18, wherein said connecting element (40). is positioned in engagement with the contact tip 25) .

20. The welding torch (.10) ,as set forth in claim 1, wherein said^' second means (.46) includes a tube

(.62) and an orifice (.64). having a preselected configu¬ ration and being connected to said tube C62) and spaced a preselected distance from said first means (44) .

21. The welding torch (.10) , as set forth in claim 20, wherein said orifice (^'64) is oriented suffi-r cient for directing said liquid delivered to the first means (_.44) to a preselected position at said first means (44) .

OMPI /.. IPO 22. The welding torch (.10), as set forth in - claim 1, including a gas flow pathway (66) positioned in fluid communication with the first means (44) and being of a configuration sufficient for directing a flow of gas from the first means (.44) to a location spaced from the contact tip assembly (.14) .

23. The welding torch (.10), as set forth in claim 22, wherein the body (12) has first and second end portions (.24,36) and a central chamber (.67) and is connected at the first end portion (24) to the first end portion (20). of the nozzle (^".181 and said gas flow pathway (66) includes said central chamber C.67)..

^'24. The welding torch CIO), as set orth in claim 12, wherein said second end portion C.36Ϊ of the body (.12) has an opening (.68). -having a preselected configuration and the gas flow pathway (66). includes said opening (1681.

25. A welding torch (101, comprising: a body (.121; a contact tip assembly (14) , having a surface

(50) and being connected to said body (12) ; an electrode pathway (.16). passing through said body (12) and said contact tip assembly (14); first means (44) for receiving a flow of liquid and controllably maintaining a flow of gas to a preselected location relative to said contact tip assembly (14) in response to gasification of said liquid at said first means (44) , said first means (44). being positioned on the contact tip assembly (14). and including an expansion element (48) defined by the surface (.50) of said contact tip assembly (14) ; (Clai 25 cont ' d) : second means (46) for controllably delivering a preselected amount of liquid to said first means (44) ; and a gas flow pathway (16) positioned in fluid communication with the first means (44) and being of a configuration sufficient for directing the flow of gas from the first means (44) to a location spaced from the contact assembly (14) .

26. A welding torch (10), comprising: a body (12) ; a contact tip assembly (14) associated with . said body (1-2) ; an electrode pathway (16) passing through said body (1-2) and said contact tip assembly (14) ; first means (44). for receiving a flow of liquid and controllably maintaining a flow of gas to a preselected location relative to said contact tip assembly (14) in response to gasification of said liquid at said first -means (44)., said first means (44) being associated with and positioned immediately adjacent said contact tip assembly (14) ; and second means (46) for controllably delivering a preselected amount of liquid to said first means (44).

OMPI /,- WIPO - -

27. In a welding torch (10) having a body (12) , a nozzle (18) , a contact tip assembly (14) and a electrode pathway (16), said nozzle (18) having first and second end portions (20,22) and being connected at

5 the first end portion (20) to the body (12) , said contact tip assembly (14) having a contact tip (25) having a first end portion (26) and -being associated with said nozzle (18) and said body (12) , said electro pathway (16) passing through said body (12) and said 0 contact tip assembly (14) and opening on said first en portion (26) of the contact tip .(25). adjacent the second end portion (22). of the nozzle (18) , the improv ment comprising: said contact tip (25) being positioned in 5 direct contact with said nozzle (18) .

28. The welding torch (10), as set forth in claim^' 27, including first means (44) for receiving a flow of liquid- and controllably maintaining a flow of gas to a preselected location relative to said contact Q tip assembly (14) in response to gasification of said liquid at said first means (44)., said first means (.44) being positioned on one of the contact tip assembly (14) and the nozzle (18) .

29. The welding torch (10), as set forth in 5 claim 27, including a current pathway- passing through the body (12) and the nozzle (18) to the contact tip (25).

30. The welding torch (10), as set forth in claim 27, wherein the welding torch (10) has an outer

30. surface (41) and including an insulating element (39) positioned on said outer surface (41 • 31. The welding torch (10) , as set forth in claim 27, wherein the nozzle (18) has an opening (30) having a surface (32) -and the contact tip (25) has a second end portion (28) positioned in said opening (30) and in contact with the surface (32) of said opening (30). * .

32. The welding torch (10) , as set forth in claim 31, wherein said opening (30) of the nozzle (18) and the second end portion (28) of the contact tip (25) have mateable tapering configurations.

33.- The welding torch (10), as set forth in claim 28, wherein the first means (44) includes an ^•expansion element (48) and the one of the contact tip assembly (14) and the nozzle (.18) having said first means (.44) has a surface (50)^' defining said expansion element (48) .

34. The welding torch (10) , as set forth in claim 33, wherein the second means (46) includes a tube (62) and an orifice (.64). having a preselected configu- Q ration and being connected to said tube (62) , said orifice (64) being oriented sufficient for.directing said liquid delivered to the first means. (44) onto the expansion element (48).

35. A welding torch (10) , comprising: a body (12) having a first end portion (24) and a central chamber (67) ; a nozzle (18) having first and second end portions 020,22) and being connected at the first end portion (20) to the first end portion (24) of the body (12) , said first end portion (20) having a surface (50) and an opening (52) having sidewalls (54) , said surface (50) including said sidewalls (54) ; a contact tip assembly (14) having a contact tip (25) , said contact tip (25) having a first end portion (20.) and being positioned in direct contact with said nozzle (18) ; an electrode pathway (16) passing through said body (12) and said contact tip (25) and opening on said first end portion (26-) of the^' contact tip (25) adjacent the second end portion (22) of the nozzle (18); first means (.44) for receiving a flow of liquid and controllably maintaining a flow of gas to a preselected location relative to said contact tip assembly (14) in response to gasification of said liquid at said first means (44) , said first means (44) including an expansion element (48) defined by the surface (50) of the first end portion (26) of the nozzle (18) ; second means (46) for controllably delivering a preselected amount of liquid to said first means (44); and a gas flow pathway (66) in fluid communicatio with the expansion element (48) and being of a con¬ figuration sufficient for directing a flow of gas from the expansion element (48) to a location spaced^*from the nozzle (18) and the contact tip _.(25) .

Λ, 36. A welding torch (10) , comprising: - a body (12) ; a nozzle (18) having first and second end portions (20,22) and being connected at the first end portion (20) to the body (12) ; a contact tip assembly (14) having a contact tip (25) , said contact tip (25) having a first end portion (26) and being positioned in direct contact with said nozzle (18); and an electrode pathway (16). passing through said body (12) and said contact tip (25) and opening on said first end portion (.26) of the contact tip (25) adjacent the second end portion (22) of the nozzle (18). .