CA1206211A - Guide for a filler metal wire, particularly for use in an arc welding machine - Google Patents
Guide for a filler metal wire, particularly for use in an arc welding machineInfo
- Publication number
- CA1206211A CA1206211A CA000418145A CA418145A CA1206211A CA 1206211 A CA1206211 A CA 1206211A CA 000418145 A CA000418145 A CA 000418145A CA 418145 A CA418145 A CA 418145A CA 1206211 A CA1206211 A CA 1206211A
- Authority
- CA
- Canada
- Prior art keywords
- guide tube
- sheath
- bore
- tube according
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/12—Automatic feeding or moving of electrodes or work for spot or seam welding or cutting
- B23K9/122—Devices for guiding electrodes, e.g. guide tubes
- B23K9/123—Serving also as contacting devices supplying welding current to an electrode
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B1/00—Vices
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Arc Welding In General (AREA)
- Insulated Conductors (AREA)
Abstract
ABSTRACT
A guide tube for guiding a wire of filler metal in an arc welding machine and optionally for applying current thereto. The tube has a metal body with a longitudinal bore through which the wire passes. Near the front of the tube there is play take up means in the form of two balls lodged in transverse passages through the tube wall. The balls are urged into the bore by conical springs which can be compressed into the form of a spiral and therefore take up so little room as to enable a sheath to be fitted over the body. An end piece projects from the front of the guide tube. It is held in place by a rim of the sheath and both the sheath and the end piece are made of refractory material to protect the guide tube. This helps to prevent the tuba becoming clogged in operation, since the splashes of molten metal do not adhere to the refractory material.
A guide tube for guiding a wire of filler metal in an arc welding machine and optionally for applying current thereto. The tube has a metal body with a longitudinal bore through which the wire passes. Near the front of the tube there is play take up means in the form of two balls lodged in transverse passages through the tube wall. The balls are urged into the bore by conical springs which can be compressed into the form of a spiral and therefore take up so little room as to enable a sheath to be fitted over the body. An end piece projects from the front of the guide tube. It is held in place by a rim of the sheath and both the sheath and the end piece are made of refractory material to protect the guide tube. This helps to prevent the tuba becoming clogged in operation, since the splashes of molten metal do not adhere to the refractory material.
Description
~ guide tube for a filler metal wire, particularly for use in an arc welding machine.
This invention relates to welding and particularly to machines and devices used to establish an electric arc between an electrode and a region of a part to be welded, in such a manner as to heat said zone to a high enough temperature for filler metal to flow thereon.
Several welding processes fall into this category. In some of them the filler metal is supplied in the form of wire which is unwound from a reel as fast as it is ued up. In -this type of method the wire is sometimes used as an arc-forming electrode and sometimes not.
For accurate welding the end of the filler wire must be suitably guided relative to the zone to be welded. Further, the wire must be moved along a weld line smoothly and without jerking.
Tradi-tionally the wire of filler metal is guided by a tube having a bore with a rear opening through which the wire enters the tube and a front open-ing through which a short length of wire projects, to be presented in a suitable position next to a weld zone. The bore of -the tube is subjected to rapid wear and numerous play take up means have been proposed to maintain a good sliding contact between the wire and the inside wall of the tube.
Play take up means are particularly useful in the common case of the filler metal guide tube also serving to supply electric curren-t to the wire, in which case the tube may be called a contact tube~ Conventional tubes give rise to numerous difficulties in operation. In particular, they give rise to arcing inside the guide tube bore, thereby pitting i-ts inside surface and deteriorating the quality of the electrical contact. However, known play
This invention relates to welding and particularly to machines and devices used to establish an electric arc between an electrode and a region of a part to be welded, in such a manner as to heat said zone to a high enough temperature for filler metal to flow thereon.
Several welding processes fall into this category. In some of them the filler metal is supplied in the form of wire which is unwound from a reel as fast as it is ued up. In -this type of method the wire is sometimes used as an arc-forming electrode and sometimes not.
For accurate welding the end of the filler wire must be suitably guided relative to the zone to be welded. Further, the wire must be moved along a weld line smoothly and without jerking.
Tradi-tionally the wire of filler metal is guided by a tube having a bore with a rear opening through which the wire enters the tube and a front open-ing through which a short length of wire projects, to be presented in a suitable position next to a weld zone. The bore of -the tube is subjected to rapid wear and numerous play take up means have been proposed to maintain a good sliding contact between the wire and the inside wall of the tube.
Play take up means are particularly useful in the common case of the filler metal guide tube also serving to supply electric curren-t to the wire, in which case the tube may be called a contact tube~ Conventional tubes give rise to numerous difficulties in operation. In particular, they give rise to arcing inside the guide tube bore, thereby pitting i-ts inside surface and deteriorating the quality of the electrical contact. However, known play
-2- i -.~
take up means are often ex-tremely complicated and consequently too expensive for practical use. They are also often excessively bulky and are therefore difficult to use i.nside a nozzle which is also intended to blow gas over the weld melt zone.
Further, such known guide -tubes suffer from accumulations o matter projected from the weld melt in molten form because of the turbulent s-tate of the melt which is accentuated by the gas je-t. The projected matter tends to cause harmful sticking between the tube and the end of the filler metal.
Further as i-t solidifies the mat-ter -tends to create accumulations of metal which in turn tend to block the outlet from the gas nozzle and, in contact tubes, encourages the formaion of unwanted arcs, particularly be-tween the surface of the tube and the nozzle. Such arcs give rise to all sorts of faults in operation, par-ticularly in machines having au-tomatic arc current regulation.
Preferred embodimen-ts of the present invention eliminate -these difficult-ies, providing guide tubes of greatly increased lifetime, while s~stantialiy improving welding quality.
In a first aspect the presen-t inve:ntion provides a guide tube for guiding filler metal wire in welding apparatus, particularly electric arc welding apparatus, the tube comprising a tubular body having a wire-guiding bore and play take up means comprising at least one thrust membar movably mounted in a passage located in the guide tube wall, which passage is trans-verse to said bore and opens our therein, said thrust member being urged by resilien-t means to project into said bore whereby a wire passing along -the bore is resiliently urged against the opposite wall of the bore by said play ~ 2~ b take up means. The improvement wherein said resilient means is a conical compression spring having turns that compress into a spiral, said spring being entirely lodged in said passage in the -thickness of t'ne guide tube wall.
Unlike a compression spring which is cylindrical, with helical turns that stack on top of each other when the spring is compressed giving a minimum compressed spring length equal to the sum of the thicknesses of the -turns, a conical spring with sprial turns can be compressed, in theory, down to the thickness of a single -turn, by vir-tue of the smaller turns being 10' received inside the larger turns~ This conical feature makes it possible -tomount a thrust member, preferably a ball, -together wi-t.h its thrust-providing spring, in a passage whose length in limited to the thickness of the guide tube wall, in such a manner that -there are no projections from the outside surface of -the tube. The degree of ball penetration into the bore o:E -the tube should be limited by a ball-retaining seat.
In preferred embodiments of the invention, the -thrust members are made of electrically insulated material, or are a-t least coated with such a material and the springs are likewise coated with insulating material. This prevents any danger of the moving parts of -the play take up means triggering parasitic arcs.
In one preferred embodiment the passage in which the spring is housed opens out in the outside surface of the guide tube wall, and the passage is closed by a sheath which surrounds the guide tube~ The largest turn of the conical spring then abuts against the sheath. The sheath is preferably ~5 designed to protect the outside surface of at least the front end of the ~6~
(1nide L~lbe ac~airlst metal sputtered up from the weld melt and adhering thereto, arld it also provldes an electrical insulation for the guide tube. Thus arasitic arc are E~revented from Eorming and solidiEied weld melt is prevented trom ac:cumulatillcl and blocking the outlet of a gas outlet nozzle, or causing the riller wire to stick t~o the tube.
~ second aspec~ of the invention provides a guide tube for guiding {iller metal wire in weldinq apparatus~ particularly electric arc welding apparatus, the tube comprising a tubular body having a wire-guiding bore and e~tended at its front end by an end piece which is not adhesive with LO respect to ~no]ten metal and which is provided with a hole extending the guide bore, the improvement wherein said end piece comprises a rear portion which is moun~ed on the front of the tubular body and is held inside a pro-tectLve sheath ~itted over said body, said sheath having an inwardly directed end piece retaining neck, and a front poition proiecting beyond the front end of the sheath towards the welding zone.
The end piece serves to prevent the end of the filler wire being accidelltally jal~ed, by weld melt entering the bore of the guide tube and deterioratillg it. The end piece is advantageously tapered towards its tip which has the effect of making it easier to weld in rece~ses in the surface ~() of the parts being welded.
In one embodimellt, the rear portion of the end piece is larger than its front portion and there is h step between the two portions providing a shoulder, that can be retained by a neck in the form of an inwardly direct-ed rim at the end oE the sheath.
Advantageously a degree of transversal play iq left for the rear portion ~6~
of -the end piece held by the end of the sheath. This enables the end piece to centre itself on the bore of the guide tube to match wear -therein~ W~len play take up means are provided in the guide tube, the filler wire progress-ively wears itself a groove in the wall of the bore. It thus moves off-centre in the course of time. I.eaving the end piece free to move means that it can follow the wear withou-t hindering the passage of filler wire.
In a preferred embodiment the cross section of the hole through the end piece varies along the leng-th of the end piece. This arrangement serves to prevent the fil]er metal wire from deposi1:ing a continuous layer of metal particles a]ong the wall of the hole as it: passes therethrough. In a hole of uniform section, such a deposit builds up to create a conductlve lining along -the length of the end piece. Such a conductive lining encourages the formation of electric arcs inside the hole through tha end piece. In a hole of varying cross section, particles are only deposited on the narrowest portions oE the hole. Thus a tapering bore is advantageous regardless of whether it tapers towards the front or towards the rear.
Embodimen-ts of the invention are described by way of example, with reference to the accompanying drawings, in which:
Figure l is a diagram showing welding apparatus fitted with a guide tube and a reel of filler metal wire.
Figure 2 is a side view in partial section of apparatus using a different technique for feeding the filler metal wire, from that shown in Figure l.
Figure 3 is an exploded longitudinal section through a guida tube for filler metal wire ~6~
Figure 4 is a longitudinal section through the front end of a variant of the guide tube shown in Figure 3.
Figure 5 is a longitudinal section through a refractory end piece.
Figures 6 and 7 are longitudinal sections through another form of guide tube for filler meta:L wire.
Figure 8 shows a detail of Figure 3 on a larger scale.
In a more detailed description of the preferred embodiment, Figure 1 shows on electric arc welding machine which can operate ei-ther according to -the metal active gas (~G) process or else according to the metal inert gas (MIG) process. It comprises a metal head 12 whose bottom end terminates in the form of a nozzle 13, having a nozzle charrlber 14 through which gas can Elow in the direction of an arrow 15. The gas is active or passive relative to the weld melt depending on the welding technique being used. The bottom 16 of the nozzle 13 opens out over a work piece 17 on which a weld fillet 18 is being made. An electric arc 20 is maintained between the work piece 17 and one end 22 of a wire 23 of filler metal. The arc serves to keep the weld zone 18 at a very high temperature and causes the end 22 vf the filler metal wire to melt away progressively.
Near to its end 22 the filler metal wire 23 is held in place by a tube 25, known as a contact tube. This tube is vertically rnounted along the axis of the noæzle chamber 14. The upper end of the tube 25 is threaded and is screwed into a cylindrical conductive support 30 which has a long-itudinal passage 32. The wire 23 is pushed Eorward to compensate for its being consumed at the end 22 by two wheels 33 which unwind it from a reel 35 and push it down the longitudinal passage 32 into the bore of the con-tact :~2~
tube 25 from whose front the end 22 projec-ts. Tne cylindrical support 30 is supplied wi-th electricity by a cable 38 connected to one terminal of a source of electricity, whose other terminal is connected to -the work piece 17 by a conductor 39. The bore along the con-tact tube 25 is calibrated to match the filler metal wire 23. It serves both to guide the wire and to supply it with electricity by contact between the bore and the wirel as is explained below.
~round the support 30 the body of the head 12 defines an annular chamber 40 having an inlet 42 passing through the wall of -the head 12. A
gas supply conduit 44 is connected -thereto for supplying a gas suitable for the welding techni~ue being used. The annular chamber 40 is connected to the nozzle chamber 14 via longitudinally ex-tending channels 46 passing through insula-ting material 48 which electrically separates the support 30 frorn the body of the head 12.
The bottom of the nozzle 13 tapers slightly -towards its axis, with its circular opening 16 surrounding a neutralizing ceramic end piece 50 (described in greater de-tail below) fixeci to the front end of the tube 25 through which the end 22 of the filler metal wire 23 projects. The electric arc 20 and the weld zone 18 are bathed in the gas blown out from the nozzle in the direction of the arrows 15.
~igure 2 shows electric arc welding apparatus 60 for use in the tungsten inert gas (TIG) process. An electrode 62 is disposed axially along the inside of the a nozzle 64 via which gas is blown in the direction of an arrow 65 towards the part 70 to be welded. The and 71 of the tungsten electrode 62 is located in the opening of the nozzle 64. The electrode ~a~
62 and the part 70 are supplied with electricity in such a manner as to maintain an arc between the end 71 of the electrode 62 and the weld ~one 72 on the part 70. Filler metal is added in -the form of a wire 75 whose end 76 advances across the arc near the point where it leaves the electrode 62 at the outlet from the nozzle 64. The wire filler metal 75 is guided by a guide tube 78 whose front end is terminated by a ceramic neutralizing end piece 79.
The contact tube 25 (Figure 31 comprises a t~ular body 80 made of an electrically conductive me-tal such as copper. It has a longitudinally extending bore 82 which inter-connects its front end with its rear end 83.
The diameter of the bore is uniform except near the rear end of -the tube where it is first enlarged at 86 and counter-sunk at the end 83 to facilitate inserting -the filler metal wire 23 therein. Going along the tube from i-ts rear end 83 to its front end 85, its outside surface comprises the following regions: the thread 26; a cylindrical portion 88 having two diametrically opposed flats to give a spanner a purchase on the tube; and then a shoulder 92 leading to a front cylindrical portion 90. A circumferentially extending groove 93 is cut into the front cylindrical portion near to the shoulder 920 Two tapering passages 95 are made through the wall of the tube per-pendicularly to its axis. The srnall ends of the tapering passages 95 open out into the bore 82. The large ends of the passages 95 open out in the front portion 90 roughly half way between the shoulder 92 and the front end 85. The passages 95 both lie on the same generator line of the tube. They receive respective balls 96 with a diameter which is slightly larger than the diameter of the small ends of the tapering passages 95. Each ball 96 is urged to _9_ project into the bore 82 by a respective compression spring 97 having conical turns with the smaller of the end turns pressing against the ball.
The larger of the end turns is located in the opening at -the larger end of the tapering passage 95 is is held therein by a cylindrical sheath 100 having an inside diameter that is substantially equal to the outside dia-meter of the cylindrical portion 90. The sheath 100 is fitted over the por-tion 90 by putting the front end 85 of the tubular body 80 into the rear end 102 of -the sheath 10. The shea-th is long enough for its rear end to abut against -the shoulder 92 when fi-tted in position. The sheath 100 is of such a thickness that when in position the outside surEace of the shea-th 100 constitutes an extension of the cylindrical portion 88 of the tube 80.
The neutrali~ing end piece 50 is a single ceramic block comprising two ju~taposed coaxial cylindrical portions, namely a Eront portion 120 and a rear portion 110, together wi-th an axial bore 115 of the same diameter as the bore 82. In the assembled tube 25 the end piece 50 has a rear face 112 which is applied agains-t the front face 85 o-E the body of the tube 80.
The rear cylindrical portion 110 of the end piece 50 is of substantially the same diameter as the inside diameter of the sheath 100 and is lodged therein. The front portion 120 is of smaller diameter than the rear portion 112 and is joined thereto via a shoulder 118. The front end of the shea-th 100 is partially closed by an inwardly turned rim 104 which bears against the shoulder 118 of the end piece 50, leaving an opening 105 via which the fron-t portion 120 of the end piece 50 projects for about 5 mm.
Thus, once the contact tube 25 is assembled, the sheath 100 abuts L
against the shoulder 92 and serves to retain bo-th the neutralizing end piece 50 on the front end of the tube 80 and also the compression springs 97 in their respective passages 95.
In operation of apparatus of the -type shown in Figure l, the tube 25 serves to guide the filler metal wire 23, letting i~ run smoothly without jerking, inside the bore 82. The wire is helcl in good electrical contact wi-th -the inside wall 99 of -the bore opposite to the passages 95, by the thrust from the balls 96. The spring force ac-ting on the balls 96 is chosen so that when the balls are lifted off -their respective seats by a wire passing through the bore 82 the balls press the wire firmly against the opposite side 99 of -the bore 82. The wire then passes through the ceramic end piece 50 to present a perfectly straight length of wire at its leading end 22, opposite to the weld melt at the ou-tlet from the nozzle 13.
Figure 8 is an enlarged view of the play take up means constituted by -the balls 96. It shows one ball 96-1 pressed against its seat 130-1 projecting out from the passage 95-1 into the bore 82. In this position the ball projects far enough into the bore to engage a wire 23 of a diameter chosen for its fit inside the bore. As shown, the wire 23 lifts the ball 96-2 off its seat 130-2, pushing it towards the larger opening 131-2 of the conical passage 95-2 at the outer surface 90 of the tube. The motion of the play take up balls between the position shown for the ball 96-l and the ball 96-2 is absorbed by their respective conical compression springs 97.
This compression spring effect is made possible in the very thin space available in the thickness of the wall of the tube 25, by virtue of the conical shape of the turns of the spring, which enables them to s-tack 2~.
inside one another, rather than on top of one another. The springs 97 are no-t shown per se in Figure ~3, but -their compressed lenyth C and iheir extended length C' are shown. It can be seen that -the absolute lengths are relatively s~lall, as is the difference between them. Thus, in a tube 25 with an outside diameter ~ of 6 mm, for guiding a wire that is 1.6 mm in diameter (F) the diameter of the bore 82 is 2 mm. Th~e wall thickness through which the passages 95 are pierced is thus 2 mm. The balls 96 are also 2 mm in diameter, res-ting on sea-ts 130 that are 1.8 m~ in diameter.
C and C' are then 0.4 and 0.6 mm respectively~
The following table summaries various examples of suitable dimensions for the play take up means shown in Figure 8. In all cases the balls are 2 mm in diameter and -their seats 130 are 1.8 mm in diame-ter. ~1 is the uncompress-ed height of the springs 97 and a is the angle of -their conicity.
A ~ C Cl E F a H
_ ~ 2.6 0.75 0.95 1.3 0.9 20 3 6 2.5 0.4 0.6 2 1.6 20 3 7.2 3 0.8 1 2.4 2 28 4 9.7 3.5 1.6 1.8 3.2 2.~ 26 4.5 All lengths are in millimeters.
By using conical springs 97 it is possible to obtain s~lfficient thrust on the wire to ensure good electrical contact between the wire and the tube, together with sufficient travel for the ball to accommodate the wear and irregularities to be expected in the wire and the tube, even after long use.
Thus, for example, a conica] spring having a relaxed length of 3 mm is used compressed in the range 0.4 to 0.6 mm. In such and arran~ement the compressed ~12 spring is virtually flat i.e., each turn is practically entirely received inside -the nex-t larger turn. In this example the spring has -three turns, using wire 25 hundreclths of a millimeter in diameter, a smalles-t turn of 1 mm inside diameter and a largest turn of 2.3 mm outside cliameter.
S This arrangement makes it possible to house the entire play take upassembly i.e., the balls 96 and the spring 97, inside the wall of the tube 80 underneath the surrounding sheath 100, without any projections requiring slots in -the sheath, or hindering the flow o~ gas -through the nozzle 13. The passages 95 are simple to produce using a conical drill bit. Minimal machin-ing is thus required to produce play take up means that do not project beyond the thickness of the tu'oe wall, even if it is as little as 1.8 mm in thickness.Depending on the nature of -the metals used and on the size of -the Eiller metal wire, a single ball may be adequate -to take up any play. This is particularly the case for soft metals i.e. aluminum and its alloys. Other-wise it is bet-ter to provide two balls, as shown in Figure 3~ or even more balls.
One of the main advantages of play take up means is maintaining good electrical contact between the filler metal wire 23 and the bore 82 of the tube 25 in spite of the tube wearing during use. This serves in particu-2~ lar pitting and to burned zones which have the effect of deteriorating electrical contact and hence make further arcing all the more likely. Using two balls as shown, serves to spread out the zone of contact between the wire and the tube, along a generator line of the tube and thereby reduces friction and hence wear.
The balls 96 are advantageously made oE electrically insula-ting material and preferably from a hard material. Balls made of quenched glass, ceramics, ruby or synthetic sapphire may be used. The use of an insulating material further reduces the chances of arcing inside -the contact tube 25. In spite of being relatively expensive, ruby balls have the advantage of being very hard, which increases the tube lifetime.
The springs 97 may be made of refractory stainless steel or of Incone:L
or of a ni-mon-ick alloy that ~dithstands high temperatures. Further it is advantageous to cover the sur~ace wlth a covering such as chromium dioxide e.g. using a pistol device or heat treatment in order to make thern electric-ally insulating. This further reduces the dangers of arcing inside the tube, thereby increasing its operating qualities and its leng-th of life. In addition -to their corrosive effects, parasitic electric arcs striking inside prior art -tubes also tend to in-terfere with the smooth mo-tion of -the wire, thereby causing non-uniformities in the welding.
The sheath 100 is made of refractory steel capable of withstanding tempera~ures of up to 1100 C for example. It is completely covered both inside and outside, with an electrically insulating material such as chromium doixide in the present example, applied in the same manner as to the springs.
This ensures t'hat drops of metal spattered up from the weld melt 18 (Figure 1) during welding, do not adhere to the sheath l00 even if they do enter the nozzle 13. This avoids solid material from accumulating on the tube 25 which could partially block the path of gas being blown out through the nozzle. Parasitic arcs are therefore avoided between the contact tube 25 and the nozzle 13. ~'inally, the sheath 100 provides thermal insulation for the body of the tube 80 and in particular for the play ta~e up means.
~he nozzle 13 itself is preferably covered with a ceramic covering. If the nozzle is made of metal, such as copper or brass, i-t is advantageously covered by projecting a ceramic powder thereon, e.g. using a pistol of the type marke-ted by CHPOLANSKY. The covering should be on the inside, on the ou-tside and on the lip at the mouth of -the nozzle. The ceramic covering provides bo-th eiectrical insulation and protection against splashes of molten metal Erom the weld melt, in that -the splashes do not adhere to the covered surface of the nozzle.
In an embodiment not shown, the sheath 100 may cover the front face 85 of the tube body 80 with the front face being covered by a wall having a hole therethrough to pass the end of the filler metal wire 26. The sheath could be made of a single block oE ceramic material. The presently pre-ferred embodiment shown in Figures 1 to 3 with its end piece 50 has the advantage that, in the event of an accident jamming the end 22 of the filler wire, molten metal tending to rise up along the contact tube 25 has no chance of adhering thereto because of the impossibility of welding the metal to the ceramic of the end piece 50. The end of the sheath 100, which is relatively thin, is -thus protected against the very high temperatures to which it would otherwise be subjected, in the absence of a neutralizing end piece 50.
In an advantageous embodiment of the invention the end piece 150 is long and tapering as shown in Figure 4. It is mounted at the front end of the tube body 80 by the sheath 100 as before. It has a cylindrical rear end portion 152 leading via a shoulder 153 to the larger or rear end of a tapering front portion 154, which front portion may be 10 mm long. The shoulder 153 abuts against the inwardly turned rim 104 of -the sheath 100 and the filler me-tal wire 23 passes through a bore 156 which extends the bore 82. The leading end 22 of the wire 23 projects frorn-the stnall front end of -the tapering portion 154. This shape of end piece 150 is particularly useful when welding a-t the bottom of a hollow such as 160 in the parts 162 to be welded. The end piece 150 prevents weld melt from accumulating at the bottom of hollows 160 and melting the bottom of the filler metal wire -to the end of the contact tube itself. The tapered shape also helps promote gas flow from the nozzle into -the bottom of the hollow 160 where the welding is being done.
In the example shown in Figure 3 the sheath 100 is held to the body of the tube 80 by three point crimping at the circumferential groove 93 in the surface 90. It thus serves both to hold the springs 97 in place in their passages 95 and to hold the end piece 50 on the front end of the tube body 80, while protecting the sides of the tube.
In Figure 5 such an end piece 190 comprises a cylindrical rear portion 192 suitable for being received in an end recess such as -the recess 172 in the tube body 144 shown in Figure 6. The end plece then has a girth portion 194 which is cylindrical bu-t of greater diameter than the rear portion 192.
The girth portion fits over the end of the tube body but is small enough to fit inside a sheath such as the sheath 100 described with reference to Figure 3. Thereafter there is a forwardly tapering front portion 196 which has a large base of smaller diameter than -the girth portion, so that it can project through the front opening 105 of the sheath, wi-th the inwardly turned lip 104 abutting against the front shoulder 197 on the girth portion 194.
~62~
Fi.gures 6 and 7 use the same reference numerals for par-ts as shown in Figure 3.
A neutralizing end piece 200 (see Figure 6) is mounted on the front of a metal tube 85. It comprises a rear portion 202 and a front por-ti.on 204 with a step or shoulder 205 at the join between said portions. The shoulder abu-ts against the inwardly directed rim 104 at the front end of the sheath 100 in order to keep the rear face of -the end piese i.n contact with the front 85 o~ the tube body 80. The diameter of the rear portion 202 i.s slightly less -than the inside diameter of the sheath 100 thereby leaving a small amount of transversal play 208. Likewise, the outside diameter of the front portion 204 of the end piece is slightly smaller than the inside diameter of the opening 105 in the end of the sheath 100. Thus the end piece 200 is capable of moving transversely inside the sheath 100 which nevertheless keeps the plane of the end piece fixed. This arrangement enables the end piece to keep i.n alignment with the filler metal wire passing therethrough, in spite of any wear that may eventually occur in the guide tube bore.
The end piece 200 has a hole 210 through which the filler metal wire passes as it leaves the guide bore 82. The hole 210 is of non-uniform cross section. In the embodiment shown in Figure 6 i-t is flared in the direction of wire movement, having a rela-tively small diameter at its rear end 21~ and a relatively large diameter at its front end 212A. The rear end diameter is substantially the same as the diameter of the guide tube bore. The hole is in the shape of a truncated cone.
In Figure 7 the hole 210 is again in the shape of a trunca-ted cone but this time it is the other way round, it is funnel shaped from a relatively large rear end 211B leading to a relatively small front end diameter 212B.
The non-uniform diameter prevents the Eiller metal wire from depositing a continuous conductive lining along the length of the walls of the hole 210.
Filler metal wire guide -tubes such as have been described above can advantageously be used in welding machines of types other than that shown in Figure 1. For e~ample, the machi.ne shown in Figure 2 does not use the guide tube to supply arc current. The tube serves to guide the filler wire 75 so that its leading end is accurately placed in the arc and so -that it advances smoothly without jerking. It is provided with a ceramic end piece 79 to avoid the filler wire becoming welded to the end of the guide tube in the event of the leading end 76 stopping accidentally. Its sides are advantageously covered with a protective sheath such as the shea-th ].00, to help avoid any drops of molten metal spattering up from the weld melt 72 and sticking to -the tube 78. Play -take up means may be fitted optionally.
take up means are often ex-tremely complicated and consequently too expensive for practical use. They are also often excessively bulky and are therefore difficult to use i.nside a nozzle which is also intended to blow gas over the weld melt zone.
Further, such known guide -tubes suffer from accumulations o matter projected from the weld melt in molten form because of the turbulent s-tate of the melt which is accentuated by the gas je-t. The projected matter tends to cause harmful sticking between the tube and the end of the filler metal.
Further as i-t solidifies the mat-ter -tends to create accumulations of metal which in turn tend to block the outlet from the gas nozzle and, in contact tubes, encourages the formaion of unwanted arcs, particularly be-tween the surface of the tube and the nozzle. Such arcs give rise to all sorts of faults in operation, par-ticularly in machines having au-tomatic arc current regulation.
Preferred embodimen-ts of the present invention eliminate -these difficult-ies, providing guide tubes of greatly increased lifetime, while s~stantialiy improving welding quality.
In a first aspect the presen-t inve:ntion provides a guide tube for guiding filler metal wire in welding apparatus, particularly electric arc welding apparatus, the tube comprising a tubular body having a wire-guiding bore and play take up means comprising at least one thrust membar movably mounted in a passage located in the guide tube wall, which passage is trans-verse to said bore and opens our therein, said thrust member being urged by resilien-t means to project into said bore whereby a wire passing along -the bore is resiliently urged against the opposite wall of the bore by said play ~ 2~ b take up means. The improvement wherein said resilient means is a conical compression spring having turns that compress into a spiral, said spring being entirely lodged in said passage in the -thickness of t'ne guide tube wall.
Unlike a compression spring which is cylindrical, with helical turns that stack on top of each other when the spring is compressed giving a minimum compressed spring length equal to the sum of the thicknesses of the -turns, a conical spring with sprial turns can be compressed, in theory, down to the thickness of a single -turn, by vir-tue of the smaller turns being 10' received inside the larger turns~ This conical feature makes it possible -tomount a thrust member, preferably a ball, -together wi-t.h its thrust-providing spring, in a passage whose length in limited to the thickness of the guide tube wall, in such a manner that -there are no projections from the outside surface of -the tube. The degree of ball penetration into the bore o:E -the tube should be limited by a ball-retaining seat.
In preferred embodiments of the invention, the -thrust members are made of electrically insulated material, or are a-t least coated with such a material and the springs are likewise coated with insulating material. This prevents any danger of the moving parts of -the play take up means triggering parasitic arcs.
In one preferred embodiment the passage in which the spring is housed opens out in the outside surface of the guide tube wall, and the passage is closed by a sheath which surrounds the guide tube~ The largest turn of the conical spring then abuts against the sheath. The sheath is preferably ~5 designed to protect the outside surface of at least the front end of the ~6~
(1nide L~lbe ac~airlst metal sputtered up from the weld melt and adhering thereto, arld it also provldes an electrical insulation for the guide tube. Thus arasitic arc are E~revented from Eorming and solidiEied weld melt is prevented trom ac:cumulatillcl and blocking the outlet of a gas outlet nozzle, or causing the riller wire to stick t~o the tube.
~ second aspec~ of the invention provides a guide tube for guiding {iller metal wire in weldinq apparatus~ particularly electric arc welding apparatus, the tube comprising a tubular body having a wire-guiding bore and e~tended at its front end by an end piece which is not adhesive with LO respect to ~no]ten metal and which is provided with a hole extending the guide bore, the improvement wherein said end piece comprises a rear portion which is moun~ed on the front of the tubular body and is held inside a pro-tectLve sheath ~itted over said body, said sheath having an inwardly directed end piece retaining neck, and a front poition proiecting beyond the front end of the sheath towards the welding zone.
The end piece serves to prevent the end of the filler wire being accidelltally jal~ed, by weld melt entering the bore of the guide tube and deterioratillg it. The end piece is advantageously tapered towards its tip which has the effect of making it easier to weld in rece~ses in the surface ~() of the parts being welded.
In one embodimellt, the rear portion of the end piece is larger than its front portion and there is h step between the two portions providing a shoulder, that can be retained by a neck in the form of an inwardly direct-ed rim at the end oE the sheath.
Advantageously a degree of transversal play iq left for the rear portion ~6~
of -the end piece held by the end of the sheath. This enables the end piece to centre itself on the bore of the guide tube to match wear -therein~ W~len play take up means are provided in the guide tube, the filler wire progress-ively wears itself a groove in the wall of the bore. It thus moves off-centre in the course of time. I.eaving the end piece free to move means that it can follow the wear withou-t hindering the passage of filler wire.
In a preferred embodiment the cross section of the hole through the end piece varies along the leng-th of the end piece. This arrangement serves to prevent the fil]er metal wire from deposi1:ing a continuous layer of metal particles a]ong the wall of the hole as it: passes therethrough. In a hole of uniform section, such a deposit builds up to create a conductlve lining along -the length of the end piece. Such a conductive lining encourages the formation of electric arcs inside the hole through tha end piece. In a hole of varying cross section, particles are only deposited on the narrowest portions oE the hole. Thus a tapering bore is advantageous regardless of whether it tapers towards the front or towards the rear.
Embodimen-ts of the invention are described by way of example, with reference to the accompanying drawings, in which:
Figure l is a diagram showing welding apparatus fitted with a guide tube and a reel of filler metal wire.
Figure 2 is a side view in partial section of apparatus using a different technique for feeding the filler metal wire, from that shown in Figure l.
Figure 3 is an exploded longitudinal section through a guida tube for filler metal wire ~6~
Figure 4 is a longitudinal section through the front end of a variant of the guide tube shown in Figure 3.
Figure 5 is a longitudinal section through a refractory end piece.
Figures 6 and 7 are longitudinal sections through another form of guide tube for filler meta:L wire.
Figure 8 shows a detail of Figure 3 on a larger scale.
In a more detailed description of the preferred embodiment, Figure 1 shows on electric arc welding machine which can operate ei-ther according to -the metal active gas (~G) process or else according to the metal inert gas (MIG) process. It comprises a metal head 12 whose bottom end terminates in the form of a nozzle 13, having a nozzle charrlber 14 through which gas can Elow in the direction of an arrow 15. The gas is active or passive relative to the weld melt depending on the welding technique being used. The bottom 16 of the nozzle 13 opens out over a work piece 17 on which a weld fillet 18 is being made. An electric arc 20 is maintained between the work piece 17 and one end 22 of a wire 23 of filler metal. The arc serves to keep the weld zone 18 at a very high temperature and causes the end 22 vf the filler metal wire to melt away progressively.
Near to its end 22 the filler metal wire 23 is held in place by a tube 25, known as a contact tube. This tube is vertically rnounted along the axis of the noæzle chamber 14. The upper end of the tube 25 is threaded and is screwed into a cylindrical conductive support 30 which has a long-itudinal passage 32. The wire 23 is pushed Eorward to compensate for its being consumed at the end 22 by two wheels 33 which unwind it from a reel 35 and push it down the longitudinal passage 32 into the bore of the con-tact :~2~
tube 25 from whose front the end 22 projec-ts. Tne cylindrical support 30 is supplied wi-th electricity by a cable 38 connected to one terminal of a source of electricity, whose other terminal is connected to -the work piece 17 by a conductor 39. The bore along the con-tact tube 25 is calibrated to match the filler metal wire 23. It serves both to guide the wire and to supply it with electricity by contact between the bore and the wirel as is explained below.
~round the support 30 the body of the head 12 defines an annular chamber 40 having an inlet 42 passing through the wall of -the head 12. A
gas supply conduit 44 is connected -thereto for supplying a gas suitable for the welding techni~ue being used. The annular chamber 40 is connected to the nozzle chamber 14 via longitudinally ex-tending channels 46 passing through insula-ting material 48 which electrically separates the support 30 frorn the body of the head 12.
The bottom of the nozzle 13 tapers slightly -towards its axis, with its circular opening 16 surrounding a neutralizing ceramic end piece 50 (described in greater de-tail below) fixeci to the front end of the tube 25 through which the end 22 of the filler metal wire 23 projects. The electric arc 20 and the weld zone 18 are bathed in the gas blown out from the nozzle in the direction of the arrows 15.
~igure 2 shows electric arc welding apparatus 60 for use in the tungsten inert gas (TIG) process. An electrode 62 is disposed axially along the inside of the a nozzle 64 via which gas is blown in the direction of an arrow 65 towards the part 70 to be welded. The and 71 of the tungsten electrode 62 is located in the opening of the nozzle 64. The electrode ~a~
62 and the part 70 are supplied with electricity in such a manner as to maintain an arc between the end 71 of the electrode 62 and the weld ~one 72 on the part 70. Filler metal is added in -the form of a wire 75 whose end 76 advances across the arc near the point where it leaves the electrode 62 at the outlet from the nozzle 64. The wire filler metal 75 is guided by a guide tube 78 whose front end is terminated by a ceramic neutralizing end piece 79.
The contact tube 25 (Figure 31 comprises a t~ular body 80 made of an electrically conductive me-tal such as copper. It has a longitudinally extending bore 82 which inter-connects its front end with its rear end 83.
The diameter of the bore is uniform except near the rear end of -the tube where it is first enlarged at 86 and counter-sunk at the end 83 to facilitate inserting -the filler metal wire 23 therein. Going along the tube from i-ts rear end 83 to its front end 85, its outside surface comprises the following regions: the thread 26; a cylindrical portion 88 having two diametrically opposed flats to give a spanner a purchase on the tube; and then a shoulder 92 leading to a front cylindrical portion 90. A circumferentially extending groove 93 is cut into the front cylindrical portion near to the shoulder 920 Two tapering passages 95 are made through the wall of the tube per-pendicularly to its axis. The srnall ends of the tapering passages 95 open out into the bore 82. The large ends of the passages 95 open out in the front portion 90 roughly half way between the shoulder 92 and the front end 85. The passages 95 both lie on the same generator line of the tube. They receive respective balls 96 with a diameter which is slightly larger than the diameter of the small ends of the tapering passages 95. Each ball 96 is urged to _9_ project into the bore 82 by a respective compression spring 97 having conical turns with the smaller of the end turns pressing against the ball.
The larger of the end turns is located in the opening at -the larger end of the tapering passage 95 is is held therein by a cylindrical sheath 100 having an inside diameter that is substantially equal to the outside dia-meter of the cylindrical portion 90. The sheath 100 is fitted over the por-tion 90 by putting the front end 85 of the tubular body 80 into the rear end 102 of -the sheath 10. The shea-th is long enough for its rear end to abut against -the shoulder 92 when fi-tted in position. The sheath 100 is of such a thickness that when in position the outside surEace of the shea-th 100 constitutes an extension of the cylindrical portion 88 of the tube 80.
The neutrali~ing end piece 50 is a single ceramic block comprising two ju~taposed coaxial cylindrical portions, namely a Eront portion 120 and a rear portion 110, together wi-th an axial bore 115 of the same diameter as the bore 82. In the assembled tube 25 the end piece 50 has a rear face 112 which is applied agains-t the front face 85 o-E the body of the tube 80.
The rear cylindrical portion 110 of the end piece 50 is of substantially the same diameter as the inside diameter of the sheath 100 and is lodged therein. The front portion 120 is of smaller diameter than the rear portion 112 and is joined thereto via a shoulder 118. The front end of the shea-th 100 is partially closed by an inwardly turned rim 104 which bears against the shoulder 118 of the end piece 50, leaving an opening 105 via which the fron-t portion 120 of the end piece 50 projects for about 5 mm.
Thus, once the contact tube 25 is assembled, the sheath 100 abuts L
against the shoulder 92 and serves to retain bo-th the neutralizing end piece 50 on the front end of the tube 80 and also the compression springs 97 in their respective passages 95.
In operation of apparatus of the -type shown in Figure l, the tube 25 serves to guide the filler metal wire 23, letting i~ run smoothly without jerking, inside the bore 82. The wire is helcl in good electrical contact wi-th -the inside wall 99 of -the bore opposite to the passages 95, by the thrust from the balls 96. The spring force ac-ting on the balls 96 is chosen so that when the balls are lifted off -their respective seats by a wire passing through the bore 82 the balls press the wire firmly against the opposite side 99 of -the bore 82. The wire then passes through the ceramic end piece 50 to present a perfectly straight length of wire at its leading end 22, opposite to the weld melt at the ou-tlet from the nozzle 13.
Figure 8 is an enlarged view of the play take up means constituted by -the balls 96. It shows one ball 96-1 pressed against its seat 130-1 projecting out from the passage 95-1 into the bore 82. In this position the ball projects far enough into the bore to engage a wire 23 of a diameter chosen for its fit inside the bore. As shown, the wire 23 lifts the ball 96-2 off its seat 130-2, pushing it towards the larger opening 131-2 of the conical passage 95-2 at the outer surface 90 of the tube. The motion of the play take up balls between the position shown for the ball 96-l and the ball 96-2 is absorbed by their respective conical compression springs 97.
This compression spring effect is made possible in the very thin space available in the thickness of the wall of the tube 25, by virtue of the conical shape of the turns of the spring, which enables them to s-tack 2~.
inside one another, rather than on top of one another. The springs 97 are no-t shown per se in Figure ~3, but -their compressed lenyth C and iheir extended length C' are shown. It can be seen that -the absolute lengths are relatively s~lall, as is the difference between them. Thus, in a tube 25 with an outside diameter ~ of 6 mm, for guiding a wire that is 1.6 mm in diameter (F) the diameter of the bore 82 is 2 mm. Th~e wall thickness through which the passages 95 are pierced is thus 2 mm. The balls 96 are also 2 mm in diameter, res-ting on sea-ts 130 that are 1.8 m~ in diameter.
C and C' are then 0.4 and 0.6 mm respectively~
The following table summaries various examples of suitable dimensions for the play take up means shown in Figure 8. In all cases the balls are 2 mm in diameter and -their seats 130 are 1.8 mm in diame-ter. ~1 is the uncompress-ed height of the springs 97 and a is the angle of -their conicity.
A ~ C Cl E F a H
_ ~ 2.6 0.75 0.95 1.3 0.9 20 3 6 2.5 0.4 0.6 2 1.6 20 3 7.2 3 0.8 1 2.4 2 28 4 9.7 3.5 1.6 1.8 3.2 2.~ 26 4.5 All lengths are in millimeters.
By using conical springs 97 it is possible to obtain s~lfficient thrust on the wire to ensure good electrical contact between the wire and the tube, together with sufficient travel for the ball to accommodate the wear and irregularities to be expected in the wire and the tube, even after long use.
Thus, for example, a conica] spring having a relaxed length of 3 mm is used compressed in the range 0.4 to 0.6 mm. In such and arran~ement the compressed ~12 spring is virtually flat i.e., each turn is practically entirely received inside -the nex-t larger turn. In this example the spring has -three turns, using wire 25 hundreclths of a millimeter in diameter, a smalles-t turn of 1 mm inside diameter and a largest turn of 2.3 mm outside cliameter.
S This arrangement makes it possible to house the entire play take upassembly i.e., the balls 96 and the spring 97, inside the wall of the tube 80 underneath the surrounding sheath 100, without any projections requiring slots in -the sheath, or hindering the flow o~ gas -through the nozzle 13. The passages 95 are simple to produce using a conical drill bit. Minimal machin-ing is thus required to produce play take up means that do not project beyond the thickness of the tu'oe wall, even if it is as little as 1.8 mm in thickness.Depending on the nature of -the metals used and on the size of -the Eiller metal wire, a single ball may be adequate -to take up any play. This is particularly the case for soft metals i.e. aluminum and its alloys. Other-wise it is bet-ter to provide two balls, as shown in Figure 3~ or even more balls.
One of the main advantages of play take up means is maintaining good electrical contact between the filler metal wire 23 and the bore 82 of the tube 25 in spite of the tube wearing during use. This serves in particu-2~ lar pitting and to burned zones which have the effect of deteriorating electrical contact and hence make further arcing all the more likely. Using two balls as shown, serves to spread out the zone of contact between the wire and the tube, along a generator line of the tube and thereby reduces friction and hence wear.
The balls 96 are advantageously made oE electrically insula-ting material and preferably from a hard material. Balls made of quenched glass, ceramics, ruby or synthetic sapphire may be used. The use of an insulating material further reduces the chances of arcing inside -the contact tube 25. In spite of being relatively expensive, ruby balls have the advantage of being very hard, which increases the tube lifetime.
The springs 97 may be made of refractory stainless steel or of Incone:L
or of a ni-mon-ick alloy that ~dithstands high temperatures. Further it is advantageous to cover the sur~ace wlth a covering such as chromium dioxide e.g. using a pistol device or heat treatment in order to make thern electric-ally insulating. This further reduces the dangers of arcing inside the tube, thereby increasing its operating qualities and its leng-th of life. In addition -to their corrosive effects, parasitic electric arcs striking inside prior art -tubes also tend to in-terfere with the smooth mo-tion of -the wire, thereby causing non-uniformities in the welding.
The sheath 100 is made of refractory steel capable of withstanding tempera~ures of up to 1100 C for example. It is completely covered both inside and outside, with an electrically insulating material such as chromium doixide in the present example, applied in the same manner as to the springs.
This ensures t'hat drops of metal spattered up from the weld melt 18 (Figure 1) during welding, do not adhere to the sheath l00 even if they do enter the nozzle 13. This avoids solid material from accumulating on the tube 25 which could partially block the path of gas being blown out through the nozzle. Parasitic arcs are therefore avoided between the contact tube 25 and the nozzle 13. ~'inally, the sheath 100 provides thermal insulation for the body of the tube 80 and in particular for the play ta~e up means.
~he nozzle 13 itself is preferably covered with a ceramic covering. If the nozzle is made of metal, such as copper or brass, i-t is advantageously covered by projecting a ceramic powder thereon, e.g. using a pistol of the type marke-ted by CHPOLANSKY. The covering should be on the inside, on the ou-tside and on the lip at the mouth of -the nozzle. The ceramic covering provides bo-th eiectrical insulation and protection against splashes of molten metal Erom the weld melt, in that -the splashes do not adhere to the covered surface of the nozzle.
In an embodiment not shown, the sheath 100 may cover the front face 85 of the tube body 80 with the front face being covered by a wall having a hole therethrough to pass the end of the filler metal wire 26. The sheath could be made of a single block oE ceramic material. The presently pre-ferred embodiment shown in Figures 1 to 3 with its end piece 50 has the advantage that, in the event of an accident jamming the end 22 of the filler wire, molten metal tending to rise up along the contact tube 25 has no chance of adhering thereto because of the impossibility of welding the metal to the ceramic of the end piece 50. The end of the sheath 100, which is relatively thin, is -thus protected against the very high temperatures to which it would otherwise be subjected, in the absence of a neutralizing end piece 50.
In an advantageous embodiment of the invention the end piece 150 is long and tapering as shown in Figure 4. It is mounted at the front end of the tube body 80 by the sheath 100 as before. It has a cylindrical rear end portion 152 leading via a shoulder 153 to the larger or rear end of a tapering front portion 154, which front portion may be 10 mm long. The shoulder 153 abuts against the inwardly turned rim 104 of -the sheath 100 and the filler me-tal wire 23 passes through a bore 156 which extends the bore 82. The leading end 22 of the wire 23 projects frorn-the stnall front end of -the tapering portion 154. This shape of end piece 150 is particularly useful when welding a-t the bottom of a hollow such as 160 in the parts 162 to be welded. The end piece 150 prevents weld melt from accumulating at the bottom of hollows 160 and melting the bottom of the filler metal wire -to the end of the contact tube itself. The tapered shape also helps promote gas flow from the nozzle into -the bottom of the hollow 160 where the welding is being done.
In the example shown in Figure 3 the sheath 100 is held to the body of the tube 80 by three point crimping at the circumferential groove 93 in the surface 90. It thus serves both to hold the springs 97 in place in their passages 95 and to hold the end piece 50 on the front end of the tube body 80, while protecting the sides of the tube.
In Figure 5 such an end piece 190 comprises a cylindrical rear portion 192 suitable for being received in an end recess such as -the recess 172 in the tube body 144 shown in Figure 6. The end plece then has a girth portion 194 which is cylindrical bu-t of greater diameter than the rear portion 192.
The girth portion fits over the end of the tube body but is small enough to fit inside a sheath such as the sheath 100 described with reference to Figure 3. Thereafter there is a forwardly tapering front portion 196 which has a large base of smaller diameter than -the girth portion, so that it can project through the front opening 105 of the sheath, wi-th the inwardly turned lip 104 abutting against the front shoulder 197 on the girth portion 194.
~62~
Fi.gures 6 and 7 use the same reference numerals for par-ts as shown in Figure 3.
A neutralizing end piece 200 (see Figure 6) is mounted on the front of a metal tube 85. It comprises a rear portion 202 and a front por-ti.on 204 with a step or shoulder 205 at the join between said portions. The shoulder abu-ts against the inwardly directed rim 104 at the front end of the sheath 100 in order to keep the rear face of -the end piese i.n contact with the front 85 o~ the tube body 80. The diameter of the rear portion 202 i.s slightly less -than the inside diameter of the sheath 100 thereby leaving a small amount of transversal play 208. Likewise, the outside diameter of the front portion 204 of the end piece is slightly smaller than the inside diameter of the opening 105 in the end of the sheath 100. Thus the end piece 200 is capable of moving transversely inside the sheath 100 which nevertheless keeps the plane of the end piece fixed. This arrangement enables the end piece to keep i.n alignment with the filler metal wire passing therethrough, in spite of any wear that may eventually occur in the guide tube bore.
The end piece 200 has a hole 210 through which the filler metal wire passes as it leaves the guide bore 82. The hole 210 is of non-uniform cross section. In the embodiment shown in Figure 6 i-t is flared in the direction of wire movement, having a rela-tively small diameter at its rear end 21~ and a relatively large diameter at its front end 212A. The rear end diameter is substantially the same as the diameter of the guide tube bore. The hole is in the shape of a truncated cone.
In Figure 7 the hole 210 is again in the shape of a trunca-ted cone but this time it is the other way round, it is funnel shaped from a relatively large rear end 211B leading to a relatively small front end diameter 212B.
The non-uniform diameter prevents the Eiller metal wire from depositing a continuous conductive lining along the length of the walls of the hole 210.
Filler metal wire guide -tubes such as have been described above can advantageously be used in welding machines of types other than that shown in Figure 1. For e~ample, the machi.ne shown in Figure 2 does not use the guide tube to supply arc current. The tube serves to guide the filler wire 75 so that its leading end is accurately placed in the arc and so -that it advances smoothly without jerking. It is provided with a ceramic end piece 79 to avoid the filler wire becoming welded to the end of the guide tube in the event of the leading end 76 stopping accidentally. Its sides are advantageously covered with a protective sheath such as the shea-th ].00, to help avoid any drops of molten metal spattering up from the weld melt 72 and sticking to -the tube 78. Play -take up means may be fitted optionally.
Claims (19)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A guide tube for quiding filler metal wire in electrical discharge welding apparatus, the tube comprising a tubular body having a wire-guiding bore and play take up means, comprising at least one pressure member movably mounted in a passage located in the wall of the tubular body, which passage is transverse to said bore and opens out herein, said pressure member being urged by resilient means to project into said bore whereby a wire passing along the bore is resiliently urged against the opposite wall of the bore by said play take up means, the improvement wherein said resilient means is a conical compression spring having turns that compress into a spiral, said spring being entirely lodged in said passage in the thickness of the wall of the tubular body.
2. A guide tube according to claim 1 wherein said passage tapers towards the bore and wherein said pressure member is a ball which is retained inside said passage towards the end of the ball's movement towards the bore.
3. A guide tube according to claim 1 wherein the pressure member is a ball made of material that is electrically insulating, at least on its surface.
4. A guide tube according to claim 3 wherein the ball is made of insulating material, namely tempered glass.
5. A guide tube according to claim 3 wherein the ball is made of insulating material, namely ceramic.
6. A guide tube according to claim 3 wherein the ball is made of insulating material, namely synthetic sapphire.
7. A guide tube according to claim 3 wherein the ball is made of insulating material, namely ruby.
8. A guide tube according to claim 1 wherein the outside surface of the spring is electrically insulating by means of a refractory coat-ing.
9. A guide tube according to claim 8 wherein the refractory coating is chromium dioxide.
10. A guide tube according to claim 1 wherein said passage opens out into the outside wall of the tube via an opening which is closed by a sheath fitted over the tube, and against which the larger end of the spring bears
11. A guide tube according to claim 10 wherein the outside surface of said sheath is covered with an electrically insulating refractory material.
12. A guide tube according to claim 1 wherein a sheath is mounted around the outside surface of the tubular body, the outside surface of the sheath being non-adhesive with respect to splashes of molten metal from the weld melt, and the sheath also serving to provide thermal insulation for the play take up means.
13. A guide tube according to claim 10 wherein the front of said tubular body is fitted with an end piece made of refractory material such as a ceramic; said end piece having a hole for the passage of the filler wire leaving the guide bore and comprising a rear portion which is held inside said sheath by an inwardly directed rim on the sheath;
and a front portion projecting beyond the front end of the sheath.
and a front portion projecting beyond the front end of the sheath.
14. A guide tube according to claim 1 including at least two passages each passage housing respective pressure members and a resilient means, and said passages being made through the wall and in line with each other and along a line parallel to the axis of the tube body.
15. A guide tube for guiding filler metal wire in welding apparatus, particularly electrio arc welding apparatus, the tube comprising a tubular body having a wire guiding bore and extended at its front end by an end piece which is non-adhesive with respect to molten metal and which is provided with a hole extending the guide bore, the improvement wherein said end piece comprises a rear portion which is mounted on the front of the tubular body and is held inside a protective sheath fitted over said body to provide thermal protection for a play take up means mounted inside the wall of the tubular body, said sheath having an inwardly directed end piece retaining neck, and a front portion projecting beyond the front end of the sheath towards the welding zone.
16. A guide tube according to claim 15 wherein said play take up means comprises at least one pressure member movably mounted in a passage located in the wall of the tubular body.
17. A guide tube according to claim 15 wherein the cross section of the hole through said end piece is non-uniform along the length of the hole.
18. A guide tube according to claim 17 wherein said hole is in the shape of a truncated cone.
19. A guide tube according to claim 15 wherein said end piece is mounted with transversal play at the end of said protective sheath.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR818124180A FR2518441B1 (en) | 1981-12-23 | 1981-12-23 | GUIDE TUBE FOR FILLED METAL WIRE, ESPECIALLY IN AN ARC WELDING MACHINE |
| FR8124180 | 1981-12-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1206211A true CA1206211A (en) | 1986-06-17 |
Family
ID=9265370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000418145A Expired CA1206211A (en) | 1981-12-23 | 1982-12-20 | Guide for a filler metal wire, particularly for use in an arc welding machine |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS58179574A (en) |
| KR (1) | KR890000926B1 (en) |
| BR (1) | BR8207455A (en) |
| CA (1) | CA1206211A (en) |
| FR (1) | FR2518441B1 (en) |
| IL (1) | IL67541A (en) |
| ZA (1) | ZA829235B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61182886A (en) * | 1985-02-12 | 1986-08-15 | Hitoshi Ashina | Contact tip of gas shield arc welder |
| JPS61245978A (en) * | 1985-04-25 | 1986-11-01 | Toyota Motor Corp | Ceramic coated torch nozzle and its production |
| JPS6241474U (en) * | 1985-08-27 | 1987-03-12 | ||
| JPS62131786U (en) * | 1986-02-08 | 1987-08-20 | ||
| FR2644091B1 (en) * | 1989-03-10 | 1992-04-24 | Faure Jean Louis | WELDING CONTACT TUBE FOR WELDING WITH FILLER METAL |
| JPWO2021039742A1 (en) * | 2019-08-29 | 2021-03-04 | ||
| FR3105935B1 (en) * | 2020-01-07 | 2022-03-11 | Polysoude | Torch intended for a single-source dual-cathode TIG welding machine |
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| US2735920A (en) * | 1956-02-21 | Valliere | ||
| BE403295A (en) * | ||||
| FR791871A (en) * | 1934-05-23 | 1935-12-18 | Manual electric arc welding device | |
| US2329904A (en) * | 1941-09-26 | 1943-09-21 | John H Howard | Apparatus for welding |
| US2538245A (en) * | 1946-10-19 | 1951-01-16 | Edward R Mchugh | Welding electrode holder switch |
| US2863984A (en) * | 1957-05-31 | 1958-12-09 | Union Carbide Corp | Gas shielded arc torches |
| GB931500A (en) * | 1961-02-07 | 1963-07-17 | Pulimax Aktiebolag | Welding electrode holder |
| US3142746A (en) * | 1961-07-28 | 1964-07-28 | Smith Corp A O | Consumable electrode arc welding apparatus |
| FR1308846A (en) * | 1961-12-08 | 1962-11-09 | Pullmax Ab | Improvements to end pieces for electric electrode welding |
| US3165662A (en) * | 1962-05-18 | 1965-01-12 | Westinghouse Electric Corp | Arc welding apparatus |
| DE1540811A1 (en) * | 1964-06-26 | 1971-10-07 | Heer & Co | Device for guiding and superimposing current of a consumable additional wire in the metal-inert-gas protective gas welding process |
| US3444353A (en) * | 1965-02-05 | 1969-05-13 | William S Wilson | Welding tips |
| FR1463824A (en) * | 1965-04-29 | 1966-12-30 | Heer & Co | Device for guiding and switching on an electric current of a fusible filler wire in the metal probing process under protection of an inert gas |
| JPS4411091Y1 (en) * | 1966-07-18 | 1969-05-07 | ||
| FR2484306A1 (en) * | 1980-06-12 | 1981-12-18 | Prunier Robert | CONTACT TUBE FOR ARC WELDING |
-
1981
- 1981-12-23 FR FR818124180A patent/FR2518441B1/en not_active Expired
-
1982
- 1982-12-15 ZA ZA829235A patent/ZA829235B/en unknown
- 1982-12-20 CA CA000418145A patent/CA1206211A/en not_active Expired
- 1982-12-22 BR BR8207455A patent/BR8207455A/en not_active IP Right Cessation
- 1982-12-22 KR KR8205740A patent/KR890000926B1/en active
- 1982-12-22 IL IL67541A patent/IL67541A/en not_active IP Right Cessation
- 1982-12-23 JP JP57235113A patent/JPS58179574A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2518441A1 (en) | 1983-06-24 |
| JPH0243582B2 (en) | 1990-09-28 |
| KR840002678A (en) | 1984-07-16 |
| JPS58179574A (en) | 1983-10-20 |
| IL67541A0 (en) | 1983-05-15 |
| ZA829235B (en) | 1983-10-26 |
| IL67541A (en) | 1986-04-29 |
| BR8207455A (en) | 1983-10-18 |
| KR890000926B1 (en) | 1989-04-14 |
| FR2518441B1 (en) | 1985-07-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |