US2217964A

US2217964A - Mechanism for butt-welding

Info

Publication number: US2217964A
Application number: US233872A
Authority: US
Inventors: Edward F Nelson
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-10-07
Filing date: 1938-10-07
Publication date: 1940-10-15
Anticipated expiration: 1957-10-15

Description

Oct. 15, 1940. E, F, NELSON MECHANISM FOR BUTT-WELDING Filed Oct. 7, 1958 2 Sheets-Sheet 1 UQ \\\N Q SX l Hfmmu Oct. 15, 1940. E. F. NELSON MECHANISM FOR BUTT-WELDING Filed 00T.. 7, 1938 2 Sheets-Sheet 2 TTORNEYS.

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this invention. is to be welded. The end of each leg, into which Patented Oct. 15, 1940 vUNITED STATES PATENT OFFICE 2,217,964 MEcnANIsM Foa Burr-WELDING Edward F. Nelson, Vallejo, Calif. Application October 7, 1938, Serial No. 233,872 11 Claims. (Cl. 219-4) This invention relates to apparatus for elecl In detail, I provide a preferably cast metallic trically butt-welding metallic objects together casing 1 having a plurality, preferably three, and is an improvement over the structure shown of radially projecting bosses A8 each being proin my prior application, Serial No. 217,345, flled vided with threaded sockets 9 for the reception July 5, 1938, for Stud Welders. of studs II which are fastened in any suitable In the aforesaid application, electro-magnetic manner, such as by pins I2, into ends of tubular means, which required a source of current for legs I3. The positioning of the bosses 8 is such energization, was utilized to actuate certain of that the legs I3 will be spaced apart equidistantly the moving parts of the apparatus. In the preson a circle whose center is the longitudinal axis 10 ent structure, such electro-magnetic means and of the casing. The opposite end of each leg l" its energization circuits are dispensed with and I3 is internally threaded to receive the threaded pressure means is substituted therefor which end of a foot I4 whose pointed end I6 may bear greatly simplifies the construction of the device, against the surface of a metallic Ymember I1 to such simplification being one of the objects of which a stud I8 or any such rod-like member Another object of the invention is to prothe feet I4 are threaded, is provided with a pluvide, in'mechanism of the class described whererality of axially extending saw slots I9 and a. in a reciprocable member is utilized, means' for nut 2I, engaging tapered threads provided at variably resisting movement of said member in the ends of the legs, is for the purpose of clamp' one direction and for rendering said member ing the segments -of the legs about the shanks capable of relatively unresisted movement in the of the feet I4 so that the latter, when adjusted opposite direction. to a desired position, may be frictionally locked The invention possesses other objects and feain place. By means of the structure just detures of advantage which will be specifically set scribed, the casing 1 may be accurately positioned forth in the detailed description of the invention in spaced relation to the surface of the memhereunto annexed. It is to be understood that ber I1, it may be adjustably spaced by screwthe invention is not to be limited to the specific ing the feet Il into or out of the ends of the form thereof shown and described as Various legs i3 0r, by Setting the feet at different de other embodiments thereof may be employed grees of extension and retraction, any angular within the scope of the appended claims. position of the stud I8 with relation to the sur- 3 Referring to the drawings; face of the member I1 may be obtained. Figure L is a vertical sectional view taken in Means is provided for supporting the stud I8 a plane passing medially and longitudinally so that it may be moved in a pre-determined through the mechanism of my invention, The path away from and toward the surface of the 36 various parts of the apparatus are shown in the member I1. Positioned centrally of the group Il positions they occupy just prior to the making of supporting legs I3, and in axial alinement with of a weld. the axis of the casing 1, is a chuck 22 one end Figure 2 isa front end elevational view of the of which is centrally bored to form a socket structure illustrated in Figure l. A portion of which receives an end of the stud I8 and is pro- 0 the view is omitted to shorten it. vided with longitudinally extending slots 23 4 Figure 3 is an enlarged vertical sectional View which form, at the end of the chuck, a pluof the dashpot piston` rality of resilient iingers 24 gripping the stud Figure 4 is a vertical sectional view, similar and frictionally retaining the latter in the socket.

' to Figure 1, showing some of the parts of the The opposite end of the chuck is provided with a apparatus in the positions they occupy during threaded bore 26 in which the threaded shank 4 the making of a weld. 21 of a plug 28 is engagedA Surrounding the pe- Figure 5 is a vertical sectional view of the vriphery of the plug 28 and having a skirt porapparatus taken in the plane indicated by the tion 29 which overlies a retaining flange 3l on line 5 5 of Figure 4. thev plug, is an insulating sleeve 32 provided on Figure 6 is a vertical sectional view of that its outer periphery with a shoulder 33. An insuf portion of the apparatus lying in and beyond lating disk 34 overlies the iianged end of the the plane indicated by the line G-B of Figure 1. plug and surrounding the disk and on the sleeve In each of the Figuresl and 4, the'welding 32 is a cap 36 having an annular lip 31 engagand control current sources are shown diagraming the shoulder 33 of the sleeve and which is i matically. internally threaded and engaged with a flange l 38 formed at one end of a tubular ram 39`so as to clamp the plug to the ram. The provision of the disk' 34 and the sleeve 32 electrically insulates the stud and its supporting chuck from the ram and the remainder of the mechanism which will presently be described. The ram 39, which is provided with a limit flange 4| spaced from the flange 38, is mounted so as to freely slide axially of and within a stationary tube 42, the latter being provided with a fixed key 43 which operates in a slot 44 formed in the ram so that motion of the ram is confined to axial directions, the key 43 serving to prevent any rotational movement between the ram and the tube. The limit flange 4| is for the purpose of restricting the axial movement of the ram to approximately one-fourth of an inch so that -a gap of this dimension may be established between the end of the stud I8 and the surface of the member |1. The opposite end of the tube 39 is provided with a pair of axially extending diametrically opposed slots 46, best shown in Figure 5, and is externally threaded to engage the threads in the bore of a hub 41 formed at the end of the casing 1. This mounts the tube in fixed relation and concentric with the casing.

Disposed concentrically within the tube, and slidable axially relative thereto through an aper- -ture provided in the tube end wall 48, is a rod 49 having at one end thereof a diametrically reduced portion 5| on which is fixedly mounted by a nut 52 a ferrule 53 provided with a radially extending flange 54. A coil spring 56 surrounds the rod and the ferrule 53 and has its ends engaging the tube end wall 48 and the ferrule ange 54 respectively. The opposite end of the rod extends through and slightly beyond the slotted end of the tube 42 and intermediate the ends of the rod is provided a collar 51 which engages, as is best shown in Figure 5, a cross bar 58 extending ltransversely of the tube and passing through the opposed slots 46 thereof. A coil spring 59 engaging the cross bar and the end wall 48 of thel plunger serves to resiliently maintain the cross bar against the collar 51. The cross bar, since it is connected to the rod by the collar is movable axially of the tube when the rod is moved. The distal ends of the cross bar are each provided with segmental arcuate flanges 80 which seat in a circular recess 6| formed in the flange 62 of .a sleeve 63 which is slidably mounted on the tube 42 and on the periphery of the sleeve ange is pressed, or otherwise suitably secured, a relatively short tubular skirt 64. A similar sleeve 66 is provided at and slidably mounted on the other end of the tube 42 and has a flange 61 to the periphery of which, and extending within the bore of the case 1, is a ltubular skirt 68. A coil spring 89 surrounds both 4sleeves 83 and 86 and has its ends bearing against the sleeve flanges 82 and 81 respectively. Both sleeves are capable of independent sliding motion along the tube 442 one, as mentioned above, being movable as the rod 491s moved and the other being movable, within certain limits, into and out of the open end of the bore of the casing 1.

Positioned at the slotted end of the tube 42 is a group of members comprising a plug 1|, which has therein a central bore through which the rod 49 slidably passes and a concentric counterbore 12 in which packing material 13 engaging the periphery of the rod is placed, a packing gland closure disk 14 also having a central bore therein through which th'e rod slidably passes ,and a cylindrical extension entering the counterbore 12 for the purpose of oomprsing the packing material 13 about the shaft, and a dashpot cylinder 18 which is axially alined with the rod 49. The plug 1|, closure disk 14 and dashpot cylinder 16 each is provided with a peripheral flange 11 lying contiguous with the others and With the end of the tube 42 and a hollow cylindrical housing 18 having a threaded bore portion which engages the threaded end of the tube 42 has therein a flange 19 engaging the flanges 11 so as to clamp the members 1|, 14 and 16 as a unit to the tube. The dashpot cylinder has therein axially spaced groups of fluid inlet ports 8| and 82 and at one end is provided with a fluid outlet opening 83. The end of the rod 49 extends into the dashpot cylinder and, as is best shown in Figure 3, is provided with a threaded shank 84 upon which is mounted la cylindrical piston 86 provided with an axial counterbore 81. A nut 88, which isthreaded on the shank 84 and is provided with a peripheral flange 89 spaced from the end wall 9| of the piston, serves to fixedly secure the piston on the rod 49. The end wall 9| of the piston is pierced by a plurality of apertures 92 and a disk valve 93, movable from a position wherein it overlies and closes the apertures 92 to a position indicated by the dotted lines 94 wherein the apertures are open, is slidably mounted on the nut 88 the flange 89 of the latter serving as a stop to limit the degree of movement of the disk valve away from the piston end wall 9|. Fluid, preferably light oil, is admitted to fill the reservoir 98 formed by the hollow interior of the housing 18, through a filling opening provided in the end wall 91 of the housing and closed by a threaded plug or screw 98. The oil filling the reservoir will, of course, also fill the cylinder 16 since it may flow thereinto through the inlet openings 8|. When the piston moves in the cylinder from right to left, as viewed in Figure 1 or 4, lsome of the oil in the cylinder will be forced by the advancing piston back through the inlet openings 8| into the reservoir and through the openings 82 into the space in back of the piston thus equalizing the pressure on both sides of the piston and permitting free and I substantially unrestricted movement thereof during approximately the first one-fourth inch of travel of the latter. As the piston progresses the periphery thereof will traverse and close the inlet openings 8| thereby causing the oil remaining in the cylinder to flow through the vent opening 83. After "the piston has closed the openings 8|, no oil may flow through the piston apertures 92 since the latter are tightly closed by the disk valve 93 which is forced against the piston end wall by the pressure of the oil being driven through the vent opening 88. However, upon a reversal of movement of the pitson, the disk valve will be forced open thereby allowing the oil to by-pass through the piston and permitting the recovery movement thereof to be made more quickly.

Means is provided for variably obstructing the vent opening 83 so that the interval of Itime that it takes the piston to travel from one end of the cylinder to that containing the vent opening 83 may be lengthened or shortened as desired. Formed concentrically of the housing end wall 91 and in axial alinement with the vent opening 83 is a -hub 99 centrally bored and threaded to receive the threaded Vstem |0| of a pointed needle valve |82. The periphery of the hub 99 is threaded to receive an internally threaded tubular nut |03 which compresses packing |04 about the needle valve stem |0| so as to prevent escape of v oil. from the reservoirA 96 past the threads ofthe generator.

stem. A hand wheel |06, riveted or otherwise secured to the stern,y is provided for manually rotzr/ting 'the stem so that various degrees of setting ofthe needle valve may be secured and a cap |01 which engages external Ithreads |08 on the housing 18 is provided for enclosing and prortecting. the valve adjusting handwheel against accidental disturbance.

Surrounding the housing 18 is the tubular head portion |09 of a handle |I| which extends radially downwardly from the housing. The head portion |09 is split longitudinally and provided with lugs ||2 each apertured to receive a bolt ||3 which clamps the head portion of the handle to the housing. The handle is hollow and, as is best shown in'Figure 6, is provided with a side opening closed by a cover plate ||4. The cover plate is designed for ready detachment so as to allow for the insertion or removal of portions of the apparatus contained within the handle, the upper end thereof having an oiset lug ||6 adapted to pass through the opening and engage the inner surface of the wall of the handle and the bottom end thereof being attached to the body of the handle by a removable screw |I1. The bottom of the handle is provided with a pair of apertures through which pass, respectively, a welding current cable ||8 and a control current cable H9. The cable ||8 extends upwardly through the handle and passes through a hollow boss |2| projecting from one side of the handle. The cable, afterexnerging from the boss I2I, is provided with a loop |22 and is attached to a connector lug |23 which is clamped between the chuck 22 and the plug 28 The purpose of the loop |22 is to provide for a greater flexibility than the cable normally possesses so that free movement of the chuck and stud I8 toward and away from the surface of the member l1 will not be hindered. The other end of the cable ||8 is connected to one terminal of a relay or circuit breaker |24, the other terminal of which is connected by a lead |26 to an output terminal of a generator vor other source of Welding current |21. A lead |28 connects the other output terminal of the Welding current source with the member I1. Disposed within the handle and electrically insulated therefrom by insulating blocks |29 mounted on the handle vby screws |30 and by a flexible insulating strip |3|, is a pair of flexible metallic blades |32 which, in their normal positions, as is shown in Figure 1, are spaced apart at their free endsf One each of the conductors |33 vand |34 in the cable |9 are connected to the respective blades |32, the former conductor being also connected to a lead |36 from a current source and the conductor |34 being connected to one end of therelay actuating coil |31. The other end of the actuating coil is connected by a conductor |38 to another lead |39 from the current source. The leads |36 and |39 may be conveniently connected to the motor |4| which drives the welding current While I have illustrated a conventional rnotor-generator for supplying the Welding current, it is to be understood that any type of apparatus for producing the current may be utilized without departing from the spirit of the invention and that the control current for operating the circuit breaker may be obtained from an auxiliary generator in the case of a welding unit driven by motors powered other than electrically.

Means is provided for manually closing the 'as viewed in Figure 1.

control circuit switch composed of the contact blades |32. In the side wall of the handle and positioned adjacent the distal end of the switch blades, is a boss |42 which is centrally bored to slidably receive a pushbutton |43 normally extending outwardly a distance beyond the end of the boss. One end of the pushbutton engages the insulating strip |3l. Mounted for pivotal movement on and depending from a pivot pin |44 carried by a vpair of spaced brackets |46, formed integrally with the handle and projecting therefrom above the boss |42, is a trigger |41 having a side portion |48 thereof engaging the projecting end of the pushbutton |43. By manually pulling the trigger so as to move it about its pivot toward ther handle the pushbutton will be moved axially of the bore of the boss |42 and the switch blade |32 lying closest to the handle side wall will be fiexed to contact the other switch blade as is clearly shown in Figure 4. Closing of the switch by the trigger |41 causes current to flow through the relay actuating coil |31 thereby closing the relay contacts and establishing the welding current circuit from the generator |21 to the stud I8 and to the member |1.

Means is provided for plurally latching parts of the apparatus operatively connected with the spring 69 against movement, and to maintain the spring under compression, and means is provided for successively releasing said latches to release and allow extension of the spring. One of these latches comprises a lever |49 pivotally mounted on a pin carried by a spaced pair of brackets |52 depending from the casing 1, so that its free end may move into and out of an aperture |53 formed in the casing side wall. At the free end of the lever |49 is formed a latch dog |54 adapted to rest, when the rod 49 is at `the extreme limit of its travel to the right, as viewed in Figure 1, against an end of the sleeve 63. The free end of the lever |49 is also provided with a pin' |56 to which is pivotally connected one end of a coupling link |51, the other end of the latter being connected by a pivot pin |58 to one end of a link |59 which is pivotally mounted on the trigger pivot pin |44. It will be seen that, when the links |51 and |59 are in the position in which they are shown in Figure 1.

and the latch dog |54 is engaging the end of the sleeve 63, the sleeve will be prevented from movement toward the left. The other of the latches comprises a lever |6| pivotally mounted on and depending from a pivot pin |62 which is carried by spaced brackets |63 provided adjacent the forward end of the casing 1. The lever |6| has thereon an extension |64 at the end of which is formed a latch dog |66 which may swing into engagement with an end of the sleeve 66 so as to prevent movement of the latter to the right, The lower end of the lever |6| is connected by a connecting rod |61 to the end of one arm |68 of a bell crank pivotally mounted onv the trigger pivot pin |44, the other arm |69 of the bell crank passing upwardly and into the bore of the casing 1 through an opening |1| formed in the side wall thereof. The distal end of the arm |69 lies in the` path of movement of the sleeve 63 along the casing bore. A guard cover |12, secured to the casing by screws |13, encloses all of the linksand levers just described with the exception of the trigger |41 which projects through an opening |14 formed in the cover. The cover, besides protecting the latch mechanism against being accidentally disturbed, conveniently serves as a stop to limit `movement of certain of the levers. Extending upwardly from the trigger, adjacent the pivot pin |44 thereof, is a short arm |16 provided at its end with a spur |11 which contacts an edge of the link |59, and a torsion spring |16 surrounding the pivot pin V|44 has one end thereof engaging the opposite edge of the link |59 and tne other end thereof resting against the inner bottom surface of the cover |12. This spring urges the link |59 upwardly to contact the spur |11 which is prevented from further movement by an extension |19 of the trigger which engages the outer surface of the cover |12. The arrangement of the parts is such that when the latch dog |54 is engaged with the end of the sleeve 63, as shown in Figure l, the axis of the pivot pin |58 will coincide with a straight line passing through the other pivot pins |56 and |44. When such a condition obtains, the lever |49 will be locked against movement irrespective of the pressure that may be exerted by the sleeve 63 against the latch dog |54. Similarly, when the end of the bell crank arm |68 rests against the inner bottom surface of the cover |12, the axis of the portion of the connecting rod |61 that connects with the pivot arm will rest below a plane passing through the opposite end of the connecting rod and the axis of the trigger pivot pin |44 with the result that the latch lever |6| is locked in position since any force exerted by the sleeve 66 to move the latch lever will be counteracted because the bell crank lever is in engagement with the fixed cover |12. However, when pressure is applied to the trigger to move the latter toward the position shown in Figure 4, the spur |11 will press against the edge of the link |59 causing the latter to swing downwardly about the pivot pin |44. As soon as the axis of the pivot pin |58 passes out of coincidence with the above-mentioned line passing through the pivot pins, the latch lever |49 will be freed and will then swing, under influence of pressure from the sleeve 63 advancing along the casing bore, downwardly, folding the links |51 and |59 as it moves, until the latch dog |53 has cleared the sleeve thereby allowing the sleeve to pass over and past the dog, the latch lever being thereafter held down by the skirt 64. Continued movement of the sleeve 63 will cause the latter to contact the end of the lever arm |69 thereby causing upward movement of the lever arm |68 about the pivot pin |44 until the pivot of the connecting rod |61 at the end of the arm |68 passes through and above the plane passing through the axes of the pivot pin |44 and the opposite end of the connecting rod where the latter connects with the latch lever |6|, whereupon the latter latch lever will be released allowing the sleeve 66 to move out of the end of the casing and over and past the latch dog |66.

In describing the cycle of operation of the apparatus, it will be well to first describe, in general terms, how the welding of the stud |9 to the surface of the metallic member |1 is accomplished. The stud, as was described above, forms one electrode of the welding circuit and theA member |1 forms the other electrode. The operation starts with the end of the stud held against and in contact with the surface of the member l1. The welding circuit is then energized and the stud is drawn away from the member to create an arc therebetween which in a short time will bring the metals of the stud and member to the melting point. Just as soon as the critical point is reached, the molten end of the stud is plunged against the melted area o1' the member, the current is turned off, and the resulting weld is allowed to congeal.

Describing the operation in terms of structure, the apparatus must first be cocked manually before it is in condition to perform, that is, after a stud I6 has been inserted in the chuck, the operator must grasp the chuck and draw it outwardly away from the casing 1. This moves the dashpot piston toward the extreme right end of the cylinder and brings the end of the sleeve 63 to its position of engagement with the dog of the latch lever |49. After the sleeve 63 has been latched, which will be indicated by the audible click of the latch dog snapping into place, the operator must push the chuck toward the casing 1. This moves the sleeve 66 into the casing bore until the latch dog |66 snaps behind the end of the sleeve, whereupon the latter Will be held in this position, and simultaneously compresses the spring 69. The operator now releases the chuck which will, under the influence of the spring 59, return to its normal position wherein the limit flange 4| is spaced approximately one-fourth inch from the end of the tube 42. The operator now grasps the handle and holds the apparatus so that the three pointed feet I6 rest against the surface of the member I1 and the end of the stud I8 is positioned on the spot to which it is desired that the stud be welded. The operator now presses the trigger |41 and maintains it in depressed position. This action first moves the pushbutton |43 to close the control circuit switch blades |32 which closes the welding current relay |24 thereby sending current through the stud and the member I1 and, secondly, trips the latch lever |49 which frees the sleeve 63. The pressure of the spring 69 immediately causes the sleeve to move toward the left-hand end of the casing 1 and, as was explained above, since the dashpot piston may move freely until it covers the inlet ports 6|, the chuck will be suddenly moved toward the casing until the limit ange 4| impinges against the end of the tube 42 whereupon further motion of the chuck is arrested. This, immediately following the institution of current flow in the welding circuit, establishes a gap between the end of the stud and the surface of the member |1 resulting in the formation of an electric arc between the two elements as is shown in Figure 4. The sleeve 63, continuing to move under the pressure of the spring 69 after its rapid motion to establish the arc gap, now encounters resistance since the piston has passed over the dashpot inlet openings 8| and must force the oil entrapped in the cylinder through the restricted vent opening 63 thereof. This retarded motion of the sleevecontinues until the latter engages the end of the bell crank arm |69 whereupon the bell crank will be moved about the pivot pin |44 until, as explained above, the latch lever dog |66 releases the sleeve 66 which, under the pressure remaining in the spring 69, will forcibly project the latter sleeve and the chuck toward the member |1 thereby plunging the molten end of the stud into the arc crater in the member 1. As soon as the operator sees that the stud and the member are joined, he releases the trigger which allows the relay |24 to open 4and disrupts the welding circuit. The interval of time elapsing between the creation of the welding arc and the joining of the heated members depends, of course, on the amount of welding current used and, in practice, does not exceed a few seconds, therefore the setting of the needle valve |02 must be obtained by trial so as to provide the proper timing 'between the release of the latch lever |49 and that of the latch lever |64.

It will be seen from the foregoing description of my invention that I have provided welding apparatus of the character described which isl capable of joining studs or other rod-like members to the surfaces of metallic objects and of producing accurately uniform welds, which accurately positions each of the studs relative to the object to which it is to be joined, which accurately times the duration of each welding operation, which is fool-proof in that the adjustments when once made mayl not be readily or accidentally disturbed, which is light in weight, and which possesses a minimum of intricate and delicate parts which are likely to get out of order.

I claim:

1. Apparatus of the class described comprising a. casing, means on said casing for engaging the surface of a metallic member forming one' electrode of an electric welding circuit so as to position said casing above said surface, means mounted for movement in said casing and for supporting a metallic element forming another electrode of said'welding circuit whereby said element may be moved from and toward and to contact said surface of the metallic member, and pressure means in said casing and operatively connected with said element supporting means for moving said element supporting first, in a direction away said member whereby an electric arc is struck between the element and the member and, secondly, for moving said element supporting means and said element toward and to contact said surface of said member.

2. Apparatus of the class a casing, ing for engaging the surface of a metallic member forming one electrode'of an electric welding circuit so as to position said casing above said surface, a ram mounted in said casing for movement from and toward the surface of said member, means for supporting on said ram a metallic element forming another electrode of said electric welding circuit whereby, when said element is moved -away from the surface of said member, an electric arc may be established between the element and the member, an expansible spring operatively connected with said ram, said spring being normally compressed and held at each end against expansion, means for releasing one end of said spring to move said ram and the element carried thereby away from the surface of said member, and means for releasing the other end of said spring to move the ram and element toward and to Contact 4said surface of the member.

3. Apparatus of th a casing, a plurality of legs carried by said casfrom the surface of described comprising ing for engaging the surface of a metallic member forming one electrode of an electric welding circuit so as to position said casing above said surface, a ram mounted in said casing for movement from and toward the surface of said member, means for supporting on said rama metallic element forming another electrode of said eleotric welding circuit whereby, when said element is moved away from the surface of said member, an electric arc may be established between the element and the member, a pair o'f sleeves slidmeans and said element, v

a plurality of legs carried by said casclass described comprising ably mounted in said casing for movement relative to each other and concentric with saidram, an expansible spring connected at its respective ends to the respective sleeves, separate releasable means for holding said sleeves against movement and for maintaining said spring under compression, separate means operatively connecting said sleeves and said means for releasing one of said sleeves to move said ram in a direction away from the surface of said member, and means operative upon movement of said first sleeve for releasing the other of said sleeves to move said ram in a direction toward the surface of said member.

4. Apparatus of the class described comprising a casing, a plurality of legs carried by said casing for engaging the surface of a metallic member forming one electrode of .an electric welding circuit so as to position said casing above said surface, a ram mounted in said casing for movement from and toward the surface o f said member, means for supporting on said ram a metallic element forming another electrode of said electric welding circuit whereby, when said element is moved away from the surface of said member, an electric arc may be established between the element and the member, a cylinder in said casing having an outlet opening and a plurality of inlet openings through which a fluid may enter said cylinder, a rod connected and movable with said ram and entering said cylinder, a piston on said rod disposed within said cylinder, said piston being movable along said cylinder when said ram is moved to pass over and close said inlet openings and to force the ram for movement together,

fluid in said cylinder through said outlet opening, means for variably obstructing the flow of fluid through said outlet opening, a pair of sleeves slidably mounted in said casing for movement relative to each other and concentric with said ram, an expansible spring interposed between and connected with said sleeves, separate releasable latches mounted on said casing and operatively connected respectively with the respective sleeves for holding the latter against movement and for maintaining said spring under compression, means connecting the separate sleeves with said ram, manually operable means for releasing one of said latches to release the sleeve held thereby, the spring whereby the latter may move the ram in a direction away from the surface of said member, and the rod whereby the piston is moved in contained in the cylinder opening thereof, and separate means for releasing the other of said latches whereby the other sleeve is released to be moved together with the ram connected thereto in a direction toward the surface of said member so that the said surface and the said element will be brought into contact with each other.

5. Apparatus of the class described comprising a casing having an axial bore therein, a plurality of legs carriedby said casing for engaging the surface of a metallic member forming one electrode of an electric welding circuit so as to position said casing above said surface, feet carried by each of said legs and extensible relative thereto whereby the spacing between the surface of said member and said casing may be adjustably varied, a tube fixed in and extending axially of said casing within the bore thereof, a ram siidably mounted in said'tube and extending from end of the latter, said ram having a chucs thereon for carrying a metallic element said cylinder to force the uid through the outlet I forming another electrode of said electric welding circuit and to be welded to said metallic member, a hollow cylinder in said casing and axially alined with said tube, said cylinder having at one end thereof an outlet opening and a plurality of inlet openings, spaced from said outlet opening, through which a iiuid may be aclmitted into said cylinder, a rod connected with said ram and extending axially of said tube into said cylinder, a piston on said rod within said cylinder, said piston being movable, when said ram is moved, along said cylinder across and to close said inlet openings thereof and to force iiuid contained in said cylinder through the outlet opening thereof, means for variably obstructing fiow of fluid through said outlet opening whereby the movement of said piston in said cylinder is resisted, a pair of separate sleeves slidably mounted on said tube, an expansible spring surrounding said tube and engaged at its ends with the respective sleeves whereby said sleeves may be moved by expansion of said spring in opposite directions along said tube, means connecting a rst sleeve with said rod whereby said rod, said ram and the element carried by the ram may be moved axially oi the tube in a direction away from the surface of said member when said iirst sleeve is moved, means extending from said ram and disposed in the path of movement of a second sleeve along said tube and engageable by said second sleeve whereby said ram and said element carried thereby may be moved, upon movement of said sleeve, in a direction toward said member so that said element and said member are brought into Contact, a first latch lever pivotally mounted on said casing and having a dog thereon engaging said first sleeve to hold the latter against movement, means for latching said first latch lever in position to hold said lever against movement to release said first sleeve, a second latch lever pivotally mounted on said casing and having a dog engaging said second sleeve for holding said second sleeve against movement whereby said spring is maintained under compression, and means for successively releasing said rst latch and said second latch.

6, Apparatus for welding a first member forming a fixed electrode of an electric welding circuit to a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on said support and movable from and toward said first member, and unitary means for moving said second member relative to said first member, primarily, in a direction away from the first member to establish an arc gap between said members and, secondarily, in a direction toward said first member to close said arc gap.

7. Apparatus for welding a first member forming a fixed electrode oi an electric welding circuit to a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on said support and movable along a deiined path from and toward said rst member, and a compressed element operatively connected with said second member and expansible in opposite directions parallel to said path of movement of the second member for, primarily, moving said second member in a direction away from the rst member to establish an arc gap between said members and for, secondarily, moving said second member toward said rst member to close said arc gap.

8. Apparatus for welding a rst member forming a xed electrode of an electric welding circuit to a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on said support and movable along a defined path from and toward said first member, an element operatively connected with said second member and expansible in opposite directions parallel to said path of movement of the second member, releasable first and second restraining means engaging opposite ends of said expansible element for holding said element in compression against expansion in said opposite directions, means for releasing said first restraining means to release one end of said expansible element and to move said second member in a direction away from said first member to establish an arc gap between said member, and means for releasing said second restraining means for releasing the opposite end of said expansible element and to move said second member toward said first member to close said arc gap.

9` Apparatus for welding a first member forming a fixed electrode of an electric welding circuit to a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on said support and movable along a defined path from and toward said first member, an element operatively connected with said second member and expansible in opposite directions parallel to said path of movement of the second member, releasable first and second restraining means engaging opposite ends of said expansible element for holding said element in compression against expansion in said opposite directions, means for releasing said first restraining means to release one end of said expansible element and to move said second member in a direction away from said first member to establish an arc gap between said member, means for releasing said second restraining means for releasing the opposite end of said expansible element and to move said second member toward said first member to close said arc gap, and means for yieldably resisting movement of said expansible element dur-ing said movement thereof to establish said arc gap between said first and second members.

l0. Apparatus for welding a first member forming a fixed electrode of an electric welding circuit to a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on said support and movable along a defined path from and toward said first member, an element operatively connected with said second member and expansible in opposite directions parallel to said path of movement of the second member, releasable iirst and second restraining means engaging opposite ends of said expansible element for holding said element in compression against expansion in said opposite directions, means for releasing said first restraining means to release one end of said expansible element and to move said second member in a direction away from said first member to establish an arc gap between said member, means for releasing said second restraining means for releasing the opposite end of said expansible element and to move said second member toward said first member to close said arc gap, and means for adjustably varying the resistance of said expansible element resisting means.

1l. Apparatus for welding a first member forming a xed electrode of an electric welding circuit to a second member forming another elec- 10 move said second member in a direction away from the first member to establish an arc gap between said member, and means operable by said primary movement of said expansible means yat the expiration of a predetermined interval of time after institution of said primary movement for releasing said expansible means for secondary movement and to move .said second member in a direction toward said rst member to close said arc gap,

EDWARD F. NELSON.