US3210522A

US3210522A - Arc-welding apparatus

Info

Publication number: US3210522A
Application number: US287259A
Authority: US
Inventors: Floyd E Adamson; James E Frederick
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1963-06-12
Filing date: 1963-06-12
Publication date: 1965-10-05
Anticipated expiration: 1982-10-05
Also published as: GB1023987A

Description

ARC-WELDING APPARATUS Filed June 12, 1965 4 Sheets-Sheet l WlTNESSES INVENTORS Floyd E. Adumson ATTORNEY j and BJames E, Frederick 6 F. E. ADAMSON ETAL 3,

ARC-WELDING APPARATUS 4 Sheets-Sheet 2 Filed June 12, 1963 1965 F. E. ADAMSON ETAL 3,210,522

ARC-WELDING APPARATUS 4 Sheets-Sheet 3 Filed June 12, 1963 Fig.4;

5, 1965 F. E. ADAMSON ETAL 3,210,522

ARC-WELDING APPARATUS 4 Sheets-Sheet 4 Filed June 12,, 1963 POWER SUPPLY UNIT HlGH SWR

United States Patent 3,210,522 ARC-WELDING APPARATUS Floyd E. Adamson, Eggertsville, and James E. Frederick, Clarence, N.Y., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 12, 1963, Ser. No. 287,259

8 Claims. ((31. 2i9130) This invention relates to arc-welding and has particular relationship to arc-welding apparatus including a highly-mobile, consumable-electrode, arc-welding gun such as is disclosed in Patents 3,038,990, granted June 12, 1962, to Cotter et al., and 3,093,728 granted June 11, 1963, to Adamson. It is broadly an obiect of this inven tion to simplify such apparatus and to reduce the cost of this apparatus.

This apparatus is used for arc-welding with a consumable electrode in a protective gaseous atmosphere which typically may be an inert gas or such a gas as carbon dioxide. Such apparatus usually includes three principal components: a gun, a control unit and a power supply unit. A simplification can be effected by eliminating the control unit as a separate item and allocating or transferring the control functions to the gun and the power supply unit. Among the functions of the separate control unit is the turning on and off of the gas flow. Attempts have been made to control the gas flow mechanically from the trigger of the gun, but heretofore, such control has not been satisfactorily reliable.

It is then an object of this invention to provide apparatus including a highly mobile gun in which the flow 'of the gas shall be effectively and reliably controlled by means of a trigger or other mechanism on the gun.

Another function of the separate control unit gun is the increase and decrease of the arc-welding current control. This control is essentially effected by controlling the speed of the motor which advances the electrode into welding relationship with the work. A simplification can be effected by supplying the motor current directly through a variable electrical impedance which is mounted on the gun. Typically, such an impedance may be a potentiometer having taps from which the motor current is derived. This impedance must be capable of carrying current of a magnitude substantially in excess of the tapped motor current and difficulty has been encountered in accordance with the teachings of the prior art in providing a satisfactory variable impedance capable of carrying this current. It is another object of this invention to provide welding apparatus including a highly mobile gun in which the speed of the welding electrode, hence the arc-welding current, may be satisfactorily controlled by the operator from a variable impedance mounted directly on the gun and connected directly in the motor supply circuit.

This invention, in one of its specific aspects, arises from the discovery that the reliable control of the gas flow by the trigger on the gun requires an adequate valve for cooperation with the trigger. In accordance with this invention, a reliable valve is provided for this purpose. The supporting structural component of the gun with which this invention concerns itself is a bracket connected in different regions to the barrel, the handle and the reel. The valve according to this invention includes a spring actuated ball which is seated in the channel in this bracket through which the gas flows in a position near the trigger in the handle in its unactuated condition. This ball blocks the flow of protective gas through the channel. The ball may be actuated by a pin which is thrust against the ball by the trigger. This opens the channel permitting gas to fiow. It is essential that when the ball is in 3,21%,522 Patented Get. 5, 1965 the unactuated position it should effectively close the channel. This object is achieved, in accordance with this invention, by providing a valve in which the ball is seated on a flexible seat, such as an O-ring, and is compressed against the seat by the spring. The ball is composed of steel and may be an ordinary ball hearing. The spring so compresses the ball against the seat as to suppress the flow of gas through the channel. The trigger moves the pin to thrust the ball away from the seat against the action of the spring opening the channel and permitting the protective gas to flow.

In accordance with another specific aspect of this invention, the electrode-drive motor, which is preferably of the direct-current type, is supplied selectively through one or the other of a pair of impedance means and through a variable impedance of low magnitude on the gun. The motor operates in its high speed range and advances the electrode at the higher speeds with one of these impedance means in the circuit and with the other impedance means in the circuit the motor operates in the low speed range and advances the electrode at lower speeds. The motor speed may be varied over the highspeed range or over low-speed range by setting the variable impedance at any position over its whole range.

The novel features considered characteristic of this invention are disclosed generally above. For a more complete understanding of this invention both as to its organization and as to its method of operation, together with additional objects and advantages thereof, reference is made to the following description of a specific embodiment, taken in connection with the accompanying drawings in which:

FIGURE 1 is a view in perspective of a gun in accordance with this invention as seen from one side;

FIG. 2 is a view in perspective of this gun as seen from the other side;

FIG. 3 is an exploded view in perspective of this gun showing its various parts;

FIG. 4 is a view in end elevation bracket of this gun;

FIG. 5 is a plan view of this bracket; and

FIG. 6 is a schematic showin the circuit of the apparatus according to this invention.

The gun shown in FIGS. 1 through 5 is on the whole similar to the gun shown in the above-identified Adamson application which includes a bracket, a handle, a barrel, a reel unit and a potentiometer unit. The handle, barrel, reel unit and potentiometer unit are suspended from, or supported by, diiferent faces of the bracket.

The bracket (FIGS. 4 and 5) is generally in the form of a block which may be of aluminum. The handle extends from one of the faces 11 of the bracket. This face engages a flange 13 on the electrode-drive motor 15 which is within the handle and has an opening 17 through which the speed reducing mechanism 19 in the motor 15 and the drive roller 21 extend. The opening 17 communicates with a recess or cavity 23 (FIG. 3) in the bracket. The electrode E passes through this recess 23 and is engaged by the roller 21 in driving relationship. A generally cylindrical boss 25 extends from a face at right angles to the face 11 and this boss carries the barrel. A boss 27 extends at an angle through a third side of the bracket and the fitting 2.9 which conducts the protective gas to the arc is connected into this boss 27. This boss 27 has an opening 31 adapted to receive the gas fitting 29 which communicates through a narrow opening 33 with a channel or opening 35 of circular section parallel to the circular opening 17 into which the drive roller 21 extends. This channel 35 has a shoulder 37 (FIG. 4) on which an O-ring 39 is mounted. A metal ball 41 which may be a ball bearing is compressed against the of the supporting O-ring by a spring 43 itself compressed by a plug 45 screwed into the channel 35 at one end. At the shoulder 37, the Opening 35 communicates with an opening 44 of small diameter which passes through the face 11. Beyond the shoulder 27, the opening 44 communicates with another opening 47 transverse to opening 44 that opens into the boss 25 to which the barrel is connected. The opening 44 carries a pin 49 the end of which extends through the surface 11 adjacent a camming surface 51 on the trigger 53 in the handle. When the trigger 53 is actuated, the pin 49 is moved inwardly moving the ball 41 against the action of the spring 43 and connecting the inlet gas channel 33 with the transverse opening 47 to the boss 27 so that protective gas flows through the boss and through the barrel.

A boss 55 of generally semicylindrical form having an opening 57 therein extends from the face of the bracket adjacent the recess 23. This boss 55 serves as a hingesleeve for a swing arm 59 which carries an idler roll 61.

The swing arm 59 which carries the idler roll 61 is bifurcated at one end and at the bifurcated end engages the boss 55 from the bracket. The arm 59 is pivotally suspended from the boss on a bolt 63 which passes through one of the fingers 65 at the end and the boss 55, and is screwed into the other finger 67. From the center of opposite sides of the arm 59, projections 69 extend. The idler roll 61 is rotatablysupported on an insulating pin '71 passing through one projection and screwed into the other. The roll is composed of a hard metal such as stainless or tool steel and is insulated from the walls of the arm by insulating washers 73. The idler roll is thus entirely out of electrical contact with any part of the arm. At its end opposite to the bifurcated end, the swing arm 59 is provided with a hole where it may be engaged and held by a thumb screw 75 which may be screwed into the bracket. When the arm is in the closed position, the idler roll 61 extends inwardly into the recess 23 in the bracket in a position to engage the welding electrode E. The idler roll 61 is urged :into firm but resilient engagement with the electrode E by a spring 77 which is compressed between the head of the thumb screw 75 and the opposite end of the arm 55.

The bracket is provided with openings 79 coaxial with the projection or boss 25 into which bushings 81 of a material such as nylon offering minimal resistance to the electrode E are secured. The electrode E passes centrally through the bushings and through the projection 25 into the barrel. The bushings 81 are held by set screws in threaded openings 83 in the bracket.

The handle is made up of a pair of elongated insulating

parts

85 and 87 which may be composed of a phenolic condensation product. These parts have substantially congruent rims and are secured abutting to form a generally oval hollow shell having a flange 89 at the top which merges into the trigger cavity 91. The trigger 53 may be slidably disposed in the cavity 91.

The electrode-drive motor 15 is disposed in the hollow portion adjacent the trigger. The flange 13 of the motor rests on the upper edge of the handle with the speed reducing mechanism 19 extending upwardly from the flange 13 and the shaft 93 of this mechanism connected to the drive roller 21. The roller 21 is insulated from the shaft 93 as disclosed in the above-mentioned Adamson application.

The inner edge of the trigger 53 engages a leaf spring 95 mounted in the hollow space formed between the two insulating

parts

85 and 87. The lower portion of the leaf spring is disposed to engage the actuating button of a microswitch 97 when the trigger is pressed. In the lower portion of the cavity formed between the parts, there is also a capacitor 99 which is connected in parallel with the motor 15. The control cable 102 for the motor 15 and the other components in the handle are inserted in an opening at the base of the shell formed between the

parts

85 and 87.

The potentiometer unit includes a box-like cover 104 of generally L cross-section, closed at the ends. The cover extends across the face and over the top of the handle-like portion 211 of the reel casing 208 of the reel unit. This cover, the bracket and the handle are secured together by bolts 1116 which pass through the top of the cover, openings in the abutting face 108 (FIG. 5) of the bracket and openings in the flange 13 of the motor 21 and are secured into threaded openings in the flange 89 of the handle. The potentiometer 110 which may be a relatively low-resistance rheostat, typically about six ohms, is disposed with its shaft 112 between a groove 114 in the handle-like end 211 of the reel casing 208 and an opening 116 in the cover 104. The knob 118 for the potentiometer 110 is secured to the shaft 112 extending through the cover by a set screw. The conductors connecting the potentiometer to the motor and to the control cable 102 pass through a groove in the bracket into the handle where they are connected to the motor 15 and the cable 102.

The barrel includes an outer sleeve or shell 163 of a material such as stainless or mild steel which is internally threaded at the end remote from the bracket. An adapter 165 externally threaded is screwed into the thread at the end of the sleeve 163. This adapter is of generally hollow cylindrical form terminating in resilient fingers 167 which extend from a shoulder on the adapter 165 and which serve to hold a nozzle 168.

The barrel also includes an electrode guide tube 170 which is held coaxial with the insulating sleeves 181 in the bracket by a generally spool-shaped conductor 171. There is also an insulating sleeve 173 between the outer shell or sleeve 163 and the guide-tube holder 171. The guide-tube holder 171 has

flanges

175 and 177. The outer surfaces of each of the

flanges

175 and 177 are insulated from the shell or outer sleeve 163 of the barrel by the insulating sleeve 173. The flange 175 is insulated from the boss or projection from the bracket by washer 179; the flange 177 is in abutting relationship with the inner end of the adapter 165 with insulating washers or sleeves 181 inter-posed between the flange 177 and the adapter.

Current is conducted to the electrode guide-tube 170 by a lug 183 soldered to the flange 175 and extending through a groove in the insulating sleeve 173 and the outer metal sleeve 163. The power conductor 185 is secured to the lug 183 in conducting engagement by a set screw 187 screwed into the upper portion of the lug. The conductor 185 is an insulated cable and the operator is protected from contact with the conductor. Within the groove where the lug 18-3 passes through sleeve 163 there is a generally rectangular insulator 189 which prevents strands from the conductor 185 from coming into contact with the outer sleeve 163. The flange 175 also has threaded openings for accommodating a set screw 191 which serves to secure the electrode guide tube 170 to the conductor 171.

The flange 175 is provided with longitudinal openings (not shown) which constitutes gas channels between the projection or boss from the bracket and the portion of the electrode guide-tube holder 171 between the

flanges

175 and 177. Because of the presence of the lug 183 and the set screw 191, these openings cannot be generally symmetrically disposed about the axis of the holder 171. Thus, any gas which flows into the space between the

flanges

175 and 177 does not enter symmetrically. The flange 177 has longitudinal openings (not shown) which are symmetrically disposed. It has been found that in spite of the dissymmetry of the entrance opening through the flange 175, the gas which is emitted through the symmetric openings has generally circular symmetry about the axis of the guide-tube. The flange 175 also 'has a circumferential groove 180. This groove is connected to the longitudinal openings (not shown) in the flange 175 through transverse openings (not shown).

from which a handle portion 211 extends.

A part of the gas which flows through the longitudinal openings is bled through the transverse openings and groove 180 into the space between flange 175 and sleeve 173 and prevents the aspiration of air into the shielding or protective gas stream.

The nozzle 168 includes a generally cylindrical stem 201 from which an internally and externally tapered outlet portion 203 extends. The tapering is such as to reduce the nozzle opening at the gas emitting end. The cylindrical portion 201 of the nozzle is so dimensioned that it is capable of being engaged and firmly held by the fingers 167 of the adapter 165. The length of the cylindrical portion 201 is such that the cylindrical portion extends well beyond the shoulder 205 of the adapter and closely hugs the internal wall of the adapter beyond the shoulder. The aspiration of air through the space 207 between the resilient fingers 167 of the adapter 165 into the shielding gas is suppressed by the joint between the adapter 165 and the cylindrical portion 201 of the nozzle 163. The nozzle 168 may be moved longitudinally inwardly or outwardly for adjustment purposes. The region of engagement of the cylindrical portion 201 of nozzle 168 and the portion of the adapter 165 behind the shoulder 205 should be sufficiently long to block the flow of air into the shielding gas through the space 207 between the fingers in the most outward position of the nozzle 168.

The electrode guide tube 170 is a tubular conductor of copper or other highly conducting material. Power is supplied to the electrode B through the guide tube 170 by contact between the electrode as it moves through the guide tube and the inner wall of the guide tube 170. It has been found that in certain situations, as in the welding of type AL4043 wire, instantaneous interruptions of the arc may occur during short time intervals when the electrode becomes entirely disconnected from the guide tube. To prevent such interruptions it is advisable to kink or otherwise provide a bend in the guide tube 170 at the electrode exit end. The electrode then contacts the guide tube at all times.

The reel unit includes the reel casing 208 which is in the form of a pan having the form of a circular are A rim 213 extends at right angles from the circular portion. The handle portion 211 extends between the top of the bracket and the casing for the potentiometer and over the portion of the barrel through which the lug 183 is secured. The power supply cable 185 passes through an insulating grommet 215 in the portion of the handle 2'11 extending over the barrel. The reel casing 208 is secured to the bracket by the screws 106 which pass through the potentiometer casing 104, the handle portion 211, the bracket and the motor flange 13 and engage the handle. The reel 230 is mounted on a spindle 219 secured by a bolt 221 to the center of the arc of the pan portion.

The reel unit has a brake for the reel. This includes a bracket 218 secured to the base of the pan portion from which a resilient arm 220 having a lip on one side extends. This arm 220 engages the outer rims of the flanges of the reel 219 producing a braking effect.

The reel unit is also provided with an idler roller 222 about which the electrode is threaded before it passes into the insulating sleeve adjacent the reel unit.

A shield 223 of transparent insulating material for example, Lucite, is mounted so that it completely encloses the pan-shaped portion of the reel casing 208. The rim of this shield 223 engages the projecting rim 213 and the bracket. The shield is secured to the spindle at the end remote from the bolt 221.

The apparatus in accordance with this invention includes a power supply unit (FIG. 6) which cooperates with the gun in a welding work W with electrode E. This unit may be of any type, but in the frequent practice of this invention is of the low-impedance direct-current type including a reactor 301 in the direct-current circuit with the electrode E and the work W. The open-circuit voltage of the supply should not be so high that if the trigger is closed when the electrode E is not in welding relationship with the work, the motor 15 is burned out.

The power supply unit includes a supply transformer 1T having a primary 1TP and a secondary 1TS. The primary 1TP may be energized from a commercial supply, for example, of 220 or 440 volts through the contacts Ma of a contactor M. The transformer IT is of the stepdown type providing a relatively low voltage of the order of 18 volts at the low voltage tap and 28 volts at the high voltage tap. The secondary 1TS is connected to supply a rectifier bridge 1R in which the rectifiers are preferably silicon diodes through the secondary BTS of a booster transformer ET. The primary BTP of the booster transformer is supplied from the output terminals of a variable transformer VT connected across the input to the primary lTP.

Across the output terminals of the rectifier a capacitor 1C is connected in parallel with a resistor 5R. The capacitor has a capacity of between about .5 and 5 microfarads and the resistor is low of the order of 500 ohms.

The positive output terminal of the rectifier RT is connected to the positive welding current supply conductor 303 usually through a meter for indicating the welding current. The negative terminal of the rectifier is connected to the negative current supply conductor 305 through the reactor 301. In the typical practice of this invention, the work W may be connected to the negativesupply conductor 305 and the electrode E to the positive conductor 303.

The welding operation is controlled directly from the gun and for cooperation with the gun the power supply unit includes additional control components. One of these is a control transformer CT having a primary CTP connected to the power busses on the power or hot side of the contact Ma. The secondary CTS of this transformer is connected to energize the coil of contactor M through back contacts of thermal switch TG which is actuable by a thermal element in the transformer and the weld switch 97 on the gun which is actuated by the trigger 53. p

The power for supplying the electrode-drive motor 15 is derived from the

conductors

303 and 305 through which the welding current is supplied and is thus dependent on the arc voltage. The motor 15 is supplied through the electrode-speed potentiometer on the gun. One terminal of this potentiometer 110 is connected to the positive conductor 303 of the supply through a pair of resistors IR and 2R. These resistors are of low resistance which typically may be about two ohms and 5 ohms. The other terminal of the potentiometer is likewise connected to the negative conductor 305 of the supply through

resistors

4R and 3R which may also be of low resistance. Typically, the resistance of 4R may be about 7%. ohms and the resistance of SR being about 5 ohms.

A switch SWR is provided for short circuiting either 3R or 2R. The setting of the switch determines the range of speed over which the motor 15 is capable of operating and thus the range of speed of the electrode E. With the switch SWR set to short circuit 3R, the motor operates in the low range and with the switch SWR set to short circuit 2R the motor operates in the 'high speed range. The potentiometer 110 of relatively low resistance (typically six ohms), but in cooperation with the switch provides a wide range of speeds for the motor and for the advance of the electrode. In each of the ranges, the potentiometer .1510 may be set over its whole scale or range, thus one potentiometer serves to control the motor over its whole range of speed and to provide a wide range of speeds for the electrode. The potentiometer is at the same time capable of conducting the motor load current for a typical motor serving to advance welding electrodes E which in the case of aluminum may vary in diameter from .020 inch to inch and in the case of steel from about .020 inch to about .047 inch, The inside diameter of the electrode guide tubes .170 for these electrodes may vary from .028 inch, for the .020 electrode to .112, for the .091 electrode. The power supply output voltage is between 14 and 35 volts.

This data for typical motors 15 used in the practice of this invention is shown in the following table:

end portion in gas communication with said barrel peripherally with respect to said guide means, said channel having interposed between said portions a plug and a plug seat and resilient means urging said plug into engagement with said plug seat so that when said plug is so in engagement it blocks the flow of gas between said portions, means actuable by said trigger through said bracket to counteract said resilient means and disengage said plug from said plug seat permitting gas to flow from said first portion Rated Max. Ar- Gr. armature Ratio Rated Output speed Full load torque Armature mature No. voltage (motor hot) Res. incl. brushes speed-No load, r.p.m.

1 24 27. 94:1 300 r.p.m.:l:5% at 10 oz.- 17 oz.-in. min. 912 ohm 9, 600 in. load, max. slope continous. speed/torque=3.5 r.p.rn./ oz.-1n. 2 24 18. 78:1 480 r.p.m.:l;5% at 6 oz.- 12 z.-in min. 12 ohm-n11n 9, 800 in. load, max. slope continuous.

speed/t0rque=6 to 7 r.p.m./oz.-in. 3 24 36:1 200 r.p.m.;l;% at 13 oz.- 23 oz.-in. min. 155:1 ohm 8, 200

in. load, max. slope continuous. speedltorque=2 r.p.m./- oz.-m.

These motors may be purchased from Globe Industries, Inc. They are identified as follows: Gr. 1Cata1ogue 29A5=6 8; Gr. 2Catalo-gue 29A571; Gr. 3Catal.ogue 5A2008.

In the use of this apparatus, the resistors 1R through 4R are set for the low speed range and the potentiometer is set for a low speed in this range and the electrode E is threaded through the gun by repeated operation of the trigger 91. When the electrode E has been advanced through the gun, the switch SWR may be set to the high position and the potentiometer 1 set to a moderate welding speed. The trigger 91 is held closed and the electrode is then touched to the work and the weld switch 97 closed by closing the trigger 5 3 on the gun and an arc is fired and the welding proceeds, During the welding operation, the potentiometer may be adjusted to set electrode speed and the welding current to the desired magnitude.

While a preferred embodiment of this invention has been disclosed therein, many modifications thereof are feasible. This invention then is not to be restricted except insofar as is necessitated by the spirit of the prior art.

We claim as our invention:

.1. Welding apparatus for welding work with a consumable electrode including a gun, a motor mounted on said :gun to be connected to said electrode for advancing said electrode in welding relationship with said work, an energizing circuit for said motor and including first and second impedance means and switch means for selectively connecting said impedance means in said circuit for setting said circuit selectively in a first setting at which said motor drives said electrode at speeds within a high-speed range and a second setting at which said motor drives said electrode at speeds Within a low-speed range, and unitary potentiometer means physically separate but electrically connected to said impedance, and mounted on said gun operable by the operator of said gun over its whole range both in said first setting and in said second setting, said potentiometer means conducting the motor current and having a low impedance .of the order of a few ohms so that it is capable of conducting the motor current.

2. A gun for welding work with a consumable electrode in a shield of gas including a bracket, a handle hav- -ing a manually-actuable trigger extending from a first portion of said bracket, a barrel extending from a second portion of said bracket, coextensive electrode guide means in said barrel and bracket for transmitting said electrode through said second portion and through said barrel, and means actuable by said trigger for supplying electrical power for arc-welding to said electrode.

3. A gun for gas-shielded arc-welding of work with a consumable electrode including a barrel for transmitting shielding gas, electrode-guide means in said barrel for transmitting said electrode int-o arc-welding relationship with said work, a manually actuable trigger connected to said barrel, means actualble on manual actuation of said trigger for supplying electrical power to said electrode for arc-welding, a gas-channel means connected in gassupply relationship to said barrel, the channel of said gaschannel means having a first portion connected to a gas supply and second portion connected to said barrel to feed gas into said barrel peripherally with respect to said guide means, a shoulder interposed between said portions, a resilient O-ring disposed on said shoulder, a plug, resilient means holding said plug in engagement with said O- ring so that said plug closes said chamber blocking the fiow of shielding gas therethrough to said barrel, and means a-ctuable by said trigger for counteracting said resilient means to disengage said plug from said O-ring permitting gas to flow through said chamber and thence through said barrel.

4. A welding gun including a supporting bracket, a barrel of said gun suspended from said bracket on one side thereof, a handle for said gun suspended from said bracket on another side thereof, coextensive electrodeguide means in said bracket and barrel, a trigger in said handle adjacent said bracket, a protective gas channel in said bracket displaced from said electrode-guide means in said bracket but terminated in said barrel peripherally with respect to the junction of said electrode guide means in said bracket and the electrode guide means in said channel, means connected to said channel for supplying shielding gas thereto, a valve in said channel between said supply means and said barrel normally maintaining said channel blocked, and means in said bracket interposed between said valve and said trigger actuable by said trigger for unblocking said valve.

5. A gun for gas-shielded arc-welding of work with a consumable electrode including a barrel for transmitting shielding gas, electrode guide means in said barrel for transmitting said electrode into arc-welding relationship with said work, a manually actuable trigger connected to said barrel, means actuable on manual actuation of said trigger tor supplying electrical power to said electrode for and second portion connected to said barrel to feed gas into said barrel peripherally with respect to said guide mean-s, valve means interposed between said portions in unactuated condition closed blocking the flow of gas between said portions, and means actuable by said trigger for opening said valve means permitting gas to flow through said chamber and thence through said barrel.

'6. Welding apparatus for welding work with a consumable electrode including a gun, a motor connected to said electrode for advancing said electrode through said gun into welding relationship with said work, an energizing circuit metallically connected to said motor and including first and second networks for setting said energizing circuit to energize said motor selectively over a first range over which said electrode is advanced at a high speed and over .a second range over which said electrode is advanced at a low speed, and also including unitary potentiometer means physically separate but electrically connected to said networks and mounted on said .gun operable by the operator of said gun over its whole range of settings to set the speed of said motor both over said first range when said first range is selected and over said second range when said second range is selected, said potentiometer means conducting the motor current.

7. Welding apparatus for welding work with a consumable electrode including a gun, a motor connected to said electrode for advancing said electrode through said gun into welding relationship with said work, power-supply means tor said motor including supply terminals, impedance means including selectable first and second impedances, potentiometric means in addition to said impedance means and electrically connected across said terminals through said impedance means, and means connecting said motor .to said potentiometric means to be supplied thereby, said potentiometric means conducting the motor current, selection of said first impedance permitting operation of said motor over a high-speed range and selection of said second impedance permitting operation of said motor over a low-speed range, said potentiometric means being variable over its whole range to set the speed of said electrode in each of said speed ranges.

8. Welding apparatus for welding work with a consumable electrode including a gun, a motor connected to said electrode for advancing said electrode through said gun into welding relationship with said work, a power supply for supplying Welding current and including terminals for connection in Welding-current supply relationship to said electrode and work, impedance means including selectable first and second impedances, potentiometric means in addition to said impedance means and electrically connected across said terminals through said impedance means, and means connecting said motor to said potentiometric means to be supplied thereby, said potentiometric means conducting the motor current, selection of said first impedance permitting operation of said motor over a high-speed range and selection of said second impedance permitting operation of said motor over a low-speed range, said potentiometric means being variable over its whole range to set the speed of said electrode in each of said speed ranges.

References Cited by the Examiner UNITED STATES PATENTS 2,3 64,920 1 2/ 44 Shatter 31473 2,465,157 3/49 'Isbell 219- 2,806,125 9/57 Miller 21'9-1'30 2,823, 33 1 2/58 Bichsel et a1 314-70 3,093,728 6/6'3 Adamson 21913O RICHARD M. WOOD, Primary Examiner.

Claims

1. WELDING APPARATUS FOR WELDING WORK WITH A CONSUMABLE ELECTRODE INCLUDING A GUN, A MOTOR MOUNTED ON SAID GUN TO BE CONNECTED TO SAID ELECTRODE FOR ADVANCING SAID ELECTRODE IN WELDING RELATIONSHIP WITH SAID WORK, AN ENERGIZING CIRCUIT FOR SAID MOTOR AND INCLUDING FIRST AND SECOND IMPEDANCE MEANS AND SWITCH MENS FOR SELECTIVELY CONNECTING SAID IMPEDANCE MEANS IN SAID CIRCUIT FOR SETTING SAID CIRCUIT SELECTIVELY IN A FIRST SETTING A WHICH SAID MOTOR DRIVE SAID ELECTRODE AT SPEEDS WITHIN A HIGH-SPEED RANGE AND A SECOND SETTING AT WHICH SAID MOTOR DRIVES SAID ELECTRODE AT SPEEDS WITHIN A LOW-SPEED RANGE, AND UNITARY POTENTIOMETER MEANS PHYSICALLY SEPARATE BUT ELECTRICALLY CONNECTED TO SAID IMPEDANCE, AND MOUNTED ON SAID GUN OPERABLE BY THE OPERATOR OF SAID GUN OVER ITS WHOLE RANGE BOTH IN SAID FIRST SETTING AND IN SAID SECOND SETTING, SAID POTENTIOMETER MEANS CONDUCTING THE MOTOR CURRENT AND HAVING A LOW IMPEDANCE OF THE ORDER OF A FEW OHMS SO THAT IT IS CAPABLE OF CONDUCTING THE MOTOR CURRENT.