USRE22310E

USRE22310E - Mechamsm fob butt weuding

Info

Publication number: USRE22310E
Authority: US
Publication date: 1943-05-11

Description

May 11,4943. y -E F, NELsoNy Re. .22,310 MEcHANIsM FOR BUTT-WELDING l Y Original Filed Oct. '7. 1938 2 heets-Sheet 2- s mg llllll HI S ATTORNEY- of the dashpot piston.

Reissue-d Mayll, 19431A Re. l22,310

UNIT ED STATlr-ISnl PATE T i OFFICE.

d I M'Eommsm Fz'clrur'r Wamme- L dward F. Nels-on. 'VallejmCaliL Original No.

2,211,964, ma omnes-1s. una,v

Serial No. 233,872, October 7,1938. Application for reissue rJuly Z5, 1942, Serial No. 452,348

This invention relates to apparatus for electrically butt-welding metallic objects together Vand is an improvement over the structure shown in my prior application, Serial No. 217,345, led July 5, 1938, for Studwelders since matured into Patent No. 2,191,494 dated February 2'?, 1940.

In the aforesaid application, electro-magnetic means, whchrequlred .a source of current for energization, was utilized to actuate certain of the moving parts of the apparatus. In the pres-.

ent structure, suchelectro-magnetic means and its energization circuits are dispensed with and pressure'means is substituted therefor which greatly simplifies the construction of the device,

such simplification being one of the objects of this invention.

Another objectl of the invention is to provide,

20' claims. y(ci. 21a-4) control vcurrent sources are shown diagrammatlcally.

In detail, I provide apreferably cast metallic casing 'I havinga plurality, preferably three, of radially projecting bosses! each being provided with threaded sockets 9 for the receptionoi' studs I I which are fastened in any suitable man'- ner,` such as by Pin l2, into ends of tubular legs I3. The positioning of the bosses 8 is such. that theiegs Il will be sp ced apart equidistantly on a circle whose cen elr is the longitudinal axis ofthe casing. The opposite end of each ed end of afoot Il whose pointed end I6 mayu leg I 3 is internally threaded to receive the threadbear 'against the surface of -a metallic member Il to which a stud IB or any such rod-like member is to be welded. The end of each leg, into which the feet Il are threaded, is provided with of relatively unresisted movement vin' the opposite direction.

The invention possesses other objects and features of advantage which will be specifically set forth in the detailed description of the invention hereunto annexed. It is to be understood that theA invention is not to be limlted'to the specific form thereof shown and describedl as various other 'embodiments thereof may be employed within the scope of l theappended claims.

Referring to the drawings:

Figure 1 is a vertical sectional view taken in a plane passing medially and longitudinally through the mechanism of my invention, The

various parts of the apparatus are shown in the positions they occupyjust prior to the making ofa weld.

Figure 2is a front end elevational view of the structure illustrated in Figure l. A portion of the view is omitted to shorten it;

Figure 3 is an enlarged vertical sectional view Figure 4 is a vertical' sectional to Figure l, showing'some of the partsof the apparatus inthe positions they occupyduring the making of a weld.

Figure 5 is a vertical sectional view of the apparatus taken in the plane indicated by the line 5- 6 of Figure 4.

Figure 6 is a vertical sectional view; of that portion of the apparatus lying in and beyond the plane indicated by the line 6 8 of Figure l.

In each of the Figures l and 4, the welding and view,A similar a plurality of axlallyextending saw slots II and a nut'2l, engaging tapered threads provided at the ends of the legs, is for the purpose of clamping the segments of the legs about the shanks ofthe feet Il so that the latter, when adjusted to a desired position, may be frictionally locked in place. By means lof the Istructure just described, the casing 1 may be accurately positioned in spaced relation to the surface of the member I1, it maybe adjustably spaced by'screwing the feet Il intol or out of the ends of the legs I3 or,

by setting. the 'feet at different degrees of ex tension` and retraction, any angular position of the stud III with relation to the surface of the member i1 may be obtained.

Means is provided forsupporting the stud I8 so that it may be moved in a pre-determined path Aaway from and toward the surface of the membore 2! in which the threaded shank 21 of a plug 2B is engaged. Surrounding the periphery of the plug 28 and having a skirt portion which overlies a retaining flange 3l on the plug, is an insulating sleeve l2 provided on its outer pel riph'ery with a shoulder 33. An Ainsulating disk 34 overlies the flanged end'of the plug and sur-V rounding the disk and on the sleeve I2 is a cap 3l having an annular lip 31 engagingl the shoully retaining the latter in the 'socket. The opposite end of the chuck is provided with a threaded yder 33 of the sleeve and which is internally with.a limit nange 4| spaced from the ange 38,

is mounted so asto 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 vis conned to axial directions, the key 43 serving to prevent any rotational vmovement between the ram and the tube.

'Ihe limit flange 4I .is for the purpose of, restricting thel axial movement of the ram to approximately onefourth of an inch so thata gap of this dimension maybe established between the end of the stud i8 and the surface of the member I1. 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 aperture provided in the tube end wall 48, is a rod 49 havinglat one end vthereof a diametrically reduced portion 5l 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 flange 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 cros's bar 58 extending transversely ofthe tube and passing through the opposed slots 46 thereof. A coil spring 59 engaging the cross bar and the end wall 48 of the 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. 'I'he distal ends of the cross bar are each provided with segmental arcuate flanges 68 which seat'in a circular recess 6| formed in the iiange 62 of a sleeve 63 which is slidably mounted on thel tube 42 and on the periphery of the sleeve flange is pressed, or otherwise suitably secured,

a relatively short tubular skirt 64. A similarl i sleeve 66 is provided at and slidably mounted on the other end of the tube 42 and has a flange 61 to theperiphery of which, and extending within the bore of the case 1, is a tubular skirt 68. .l A--coil spring 69 surrounds both sleeves 63 and 66 and has its ends bearing against the sleeve'anges y62 and 61 respectively.. Both sleeves are capable of independent sliding motion along the tube 42 one, as mentioned above, being movable as the rod 49 is moved and the other being movable,

within certain limits, into and out o! end olf the bore of the casing 1. t

Positioned at theslotted end of the tube 42 is the open a group oi members comprising a plug 1|, which has therein a central bore through which the rod 49 slidably passes and a concentric counter# bore 12 in which packing vmaterial 13 engaging the periphery of the rod isV placed, a packing gland closure disk 14 also' having a central bore Awhich is forced against the piston end wall by` therein through which the rod slidably passes and a cylindrical extension entering the counterbore 12 for the purpose of compressing the packingA material 13 about the shaft, and a dashpot cylinder 16 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 l42 and a hollow cylindrical housing 18 having a threaded bore portion which engages the threaded end of the tube 42 has therein a ange 19 engaging the flanges 11 so as to clamp the members 1I, 14 and 'I6 as a unit to the tube. The.A dashpot cylinder has therein axially spaced groups of fluid inlet ports 8| and 82 `and at one end is provided with a iiuid outlet opening 83. The end of the rod 49 extends into Ythe dashpot cylinder and, as is best shown in Figure 3, is provided with a. threaded shank 84 upon which is mounted a cylindrical piston 86 provided with an axial counterbore 81. A nut 88, which is threaded 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 82 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 iiange 69 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 ll the reservoir 96 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, some 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 substantially unflow through the piston apertures 92 since the y latter are tightly closed by the disk valve 83 the pressure of the oil being driven .through the 'vent opening 83. However, upon a reversal of movement of the piston, 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 time that it takes the piston to travel from one end ofthe cylinder to that containing the vent opening' 83 may be lengthened or y 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 stem IUI of a pointed needle valve |02. The Aperiphery of the hub 98 lis threaded to receive Van internally threaded tubucasio wise secured to the stem, is provided for manu- 4 ally rotating the stern so that various degrees o! setting of the needle valve may be secured and a cap |21 which engages external threads Ill on the housing 'I4 is provided for enclosing and protecting the valve'adiusting hancinwheel` against accidental disturbance.

Surrounding the housing 12 is the tubular head portion |55 of a handle which extends radially downwardly from the.' housing. The head portion |55 is split longitudinally and provided with lugs ||2 each apertured in receive a bolt ||2 which clamps the head portion of the handle to the housing. The Ihandle is hollow and, as is best shown in Figure 6, is provided with a side opening closed by a cover plate ||4. AThe 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 oiiset lug |'I5 adapted to pass through the opening and engage the inner surface oi the wall of the handle and the bottom end thereof -beingv attached to the body of the handle by a removable screw ||1. 'Ihe bottom ofthe handle is provided with a pair of apertures. through which pass, respectively, a welding current cable lil and a control current cable H2. The cable ex' tends upwardly through the handle and passes through a hollow boss |2| projecting from one side of the handle. The cable, after emerging from the boss. |2|, is provided with a loop |22 and is attached to a connector lug |22 which is clamped between the chuck 22 and the plug 22. The purpose of the loop |22 'is to provide for a greater ilexibility than the cable normally possesses so that free movement of the chuck and stud Il toward and away from thel surface of the member |1 will not be hindered. The other end oi the cable I I5 is connectedto one terminal of a relay or circuit breaker .|24, the other terminal of which is connected by a lead |25 to an output terminal of a generator or other source of welding current |21. A lead |25 connects the other output terminal of the'. welding current source with the member l1. Disposed within the handle and electrically insulated therefrom by insulating blocks |29 mounted on the handle by screws |25 and by a ilexible insulating strip |2I, is a pair of flexible metallic blades |22 which, in their normal positions, as is shown in Figure 1, are spaced apart at their free ends. One each Means is provided for manually closing the control circuit switch composed of the contact blades |22. 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 |42 normally extending outwardly Aa vdistance beyond the end of the boss. One end of the pushbutton engages the insulating strip |2|. Mounted for pivotal movement on and depending from a pivot pin |44 carried by a pair of spaced brackets |45,

' formed integrally with the handle and projecting therefrom above the boss |42, is a trigger |41 having a side portion |42 thereof-engaging the projecting end of the pushbutton |42. By manually pulling the trigger so as to move it about its pivot toward the handle `the pushbutton will be moved axially of thebore of the boss |42 and the switcnblade |22 lying closest to the handle sidewall will be flexed to contact the other switch blade as is clearly shown ,in- Figure 4; Closing of the switch by the trigger |41 causes 'current'todlow through the relay actuating coil |21 thereby closing the relay contacts and establishing the welding current circuit from the generator |21 to the stud I5 and to the member |1.

Means is provided for plurally latching parts of the apparatus operatively connected with the spring against movement, and to maintain the spring under compression, and means is prox, vided for successively releasing said latches to ofthe conductors |22 and |34 in the cable ||5 c isy to be understood that any type of apparatus for producing the current may be utilized without 'departing from the spint or the invention nid that the control current for operating the circuit breaker may be obtained from an auxiliary generator in the `case of s. welding unit driven by Ultr powered other than electrically.

.release and allow extension of the spring. One

of these latches comprises 'a lever |45 pivotaliy mounted on a pin I5| 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 |52 formed in .the casing side wall. At the free end of the lever |45 is formed a latch -dog |54 adapted to rest, when the rod 45 is at vthe extreme `limit of its travel to the right, as

viewed in Figure l, against an end of the sleeve 52. 'I'he free end of the lever |45 is also provided with a pin |55 to which is pivotally connected one end` of a coupling link |51, the other end i of the latter being connected by a pivot pin |55 to one end of a link |55 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 l and the latch dog |54 is engaging the endof the sleeve 52, the sleeve will be prevented from movement toward.` the left. The other of the latchesv comprises alever |5| pivotally mounted on and depending from a pivot pin |52 which is carried by spaced/brackets |52 provided adjacent the forward end of the casing 1. The lever |5| has thereon an extension |54 at the end of which is formed a latchdog |55 which may swing into engagement with an end of the sleeve 55 so as to prevent movement of the latter to the right, as viewed in Figure l. Tn'i'ie lower end of the lever- .|5| iis connectedby a connecting .rod |51 to the end oi one arm |55 of a b`ell crank pivotally nounted on the trigger pivot pin |44, the other arm |55 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 |52 lies in the path of movei ment oi the sleeve 52 along the casing bore. A

guard cover |12, secured to the casing'by screws |12, vencloses ali,of the linksv and levers lust described with the/e'xception of the trigger |41. which projects through an opening |14 formed in the cover, The cover, besides protecting` the latch mechanism against being accidentally dis sleeve 63 against the latch dog |54.

turbed, conveniently serves as a stop to limit movement of certain of the levers. Extending upwardly from the trigger, adjacent theA pivot.

arrangement of the `parts is such that when the v latch dog |54 is engaged with the end of the the sleeve 63, as shown in Figure 1, the axis of the` pivot pin |56 will coincide witha 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 bythe 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 `||i1 i that connects with the pivot armnwill restl below a plane passing through the opposite end of the A connectingrod 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 6G to move the latch lever will be counteraeted because the bell crank lever is in engagement with the fixed cover |12. However, when pressure is appliedvto 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 |56 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 B3 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 ybeing thereafter held Y' 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 |66 passes through `and above the plane passing through the axes of thepivot pin |44 and the opposite end of the connecting rod where the latter connects with the latch lever IBI, whereupon the latter latch lever will be released allowing the sleeve B6 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 ap- 4 paratusit will be well to first describe, in general terms, h'ow the welding of the stud I8 to the surface of the metallic member |1 is accomplished. 'I'he stud, as was described above, forms one electrode of the welding circuit and the member I1 forms the other electrode. The operation starts with the end of the stud 'held against and in contact with the surface of the member |1. The welding circuit is then energized and the stud is drawn away from the member to create an arc therebetween which i-n a short time will bring the metals ofthe 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 of the member, the current is turned ol, andthe 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 |8 has been inserted inthe chuck, the operator must grasp the chuck and draw it out, wardly 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 0perator 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 |6 rest against the surface of the member I1 and the end of the stud |8 isV 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 rst moves the pushbutton |43 to close the control circuit switch blades |32 which closes thewelding current relay |24 thereby sending current through the stud and the member |1 and, secondly, trips the latch lever l|49 which frees the Asleeve 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 yimmediately 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 I1' resulting in the formation of an electric arc between the two elements as is shown in Figure 4. 'I'he sleeve 63, continuing to move under the pressure Vof 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 83 thereof. This retarded motion of the sleeve continues 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 and disrupts the weldingcircuit. The interval of time elapsing be- Y tween the creation of the weldingy are and the v ,810 fore the setting of the needle valve |02 must be obtained by trial so as to provide the proper timing between the release oi' the latch lever Ils and that of the latch lever |84.

It will be seen from the foregoing description of my invention that I have provided welding apparatus of the character described which is capa- 'ble of joining studs or other rod-like members which are likely to get out of order.

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 posi- Vtion 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 means and said element," first, in a direction away from the surface of 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 contactl said surface of said member.l

2. Apparatus of the class described comprising a casingfa plurality of legs carried by said casing for engaging the surface of a metallic member to the respective sleeves, separate releasable means for holding said sleeves against movement A and for maintaining said spring under compression, separate means operatively connecting said sleeves and said ram for movement together, 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 ilrst sleeve for releasing the other of A.

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 of said member, means for supporting on said ram a metallic element forming another electrodeof said electricv 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 disposedV 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 duid in said cylinder through said outlet opening, means for variably obstructing the flow of fluidthrough 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 forming one electrode of an electric welding circuit so as to position said casing above said sur- I face, a ram mounted in said casing for movement A 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 oneend 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 said surface of the member.

3. lApparatus 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 of said member, A

means for supporting on said ram a metallic element forming another electrode of said electricwelding circuit whereby, when said element fis movedaway from the surface of said member, an electric may be established between the element and e member, a-,pair of sleeves slidably mounted in said casing foi-'movement relative to each other and concentric-with saidram, an ex' pansible spring connected at its respective ends said spring under compression, means connecting the separate sleeves with said ram, manually op'- erable means for releasing one of said latches to release the sleeve held thereby, the spring whereby the latter may move the ram 4in a direction away from the surface of said` member,- and the rod whereby the piston is moved in said cylinder to force the fluid contained in the cylinder through the outlet opening thereof. and separate means for releasing the other yof said latches whereby the other sleeve is released to be moved togetherl 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'clafss described comprising a casing having an axial bore therein, a plurality of legs carried by saidcasing for engaging the f surface of a metallic member forming on@ elec- -another electrodeof .said electric welding circuit v 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 oi 4inlet openings, spaced `from said` outlet opening, through which a fluid maybe admitted 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 fluid contained in said cylinder through the outlet opening thereof, means for variably obstructing flow 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 expansion of said spring in 'opposite directions along said tube, means connecting a first sleeve with said rod whereby said rod, said ram and the element carried by the ram may be moved axially of theV tube in a direction away from the surface of said member when said first sleeve is moved, means extending from said ram and disposed in the path of movement of a second sleeve along saidtube 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 thereonengaging said first sleeve to hold the latter against movement, means for iatching said iirst latch lever in position to hold said lever against movement to release said first sleeve, a second latch lever pivotally mountedon 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 iirst 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 cricuit, comprising a support, said second member being mounted on said support and movable from and toward said Afirst member, and unitary means for moving said seco nd member relative to said iirst member, primarily, in a direction away from the rst member to establish an arc gapbetween said memmember 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 :drst member to establish an arc gap between said members and for, secondarily, moving said second member toward said first member to close said arc gap.

Cil

support and movable along a Vdefined path from and toward said first member, an element operatively connected withsaid second member and expansible in opposite directions parallel to expansion in said opposite directions, means for be moved by .bers and, secondarily, in a direction toward said 8; Apparatus for welding a rst member form- 1 ing a fixed electrode of an electric welding circuit to 4a second member forming another electrode of said welding circuit, comprising a support, said second member being mounted on ysaid releasing said first restraining means to release one end of said expansible element and to move said second Vmember 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 rst member to close said arc gap.

9. Apparatusfor welding a rst member forming a fixed electrode of' an electric welding circuitto 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 rst 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 endsof said expansible element for holding said element in compression against expansion in said opposite directions, means for releasing said iirst restraining means to release one end of said expansible element and to move said second member in a direction away from said rst member to establish an arcgap between said member, means for releasing said second restraining means for releasing theopposite 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 during said movement thereof to establish said Yarc gap between said first and second members.

10. 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 rst 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 sai irstrestraining means to release one end of 4sgid expansible element andto -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 saidsecond member toward said first member to close said arc` gap, and means for adjustably varying the resistance of said expansible element resisting me'ans. i

1.1.. `Apparatus for welding a rst member forming' a fixed electrode oi." an electric welding circuit toa second member trode of said welding circuit, comprising a sup,

forming another elecand toward said rst member, a compressed element operatively connected and movable with said second member and expansible in opposite directions parallel to said path of movement oi means for limiting the associated movement of the ram, a power spring between the push rings, a latch for restraining movement of each push ring, manually operated means for releasing the the second member, means for releasing said exlatch of the rlrst push ring, and means operated pansible element for primary movement and to move said second member in a direction away from the first memberto establish an arc gap between said member, and means operable by said primary movement of said expansible means at 10 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 first member to close said arc gap.

12. In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a pair of latches for restraining the action of the spring,

means for releasing one of the latches to permit the spring to move the ram in one direction, and time controlled means initiated by the releasing means for releasing the other latch to permit the spring to move the ram in the other direction.

`13..In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a pair of latches for restraining the action of the spring,

manually actuated means for closing the welding' 30 circuit and for4 releasing one of the latches to permit the spring to move the ram in-one direction, and time controlled means initiated by the releasing means for releasing the other latch to permit the spring to move the ram in the other direction.

14. In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a pair of latches for restraining the action of the spring. 40

a switch for controlling the welding circuit, manually controlled means for operating the switch and for releasing one of the latches to permit the spring to move the ram in one direction, and l time controlled means initiated by the releasing 5 means for releasing the other latch to permit the spring to move the ram in the other direction.

15. In a welding apparatus, a casing, a ram slidably mounted in said casing, -ilrst and second push rings slidably mounted in said casing and operatively connected to said ram, a power spring between the-push rings, time controlled means for limiting the movement of the ilrst push ring, a latch for restraining movement of each push ring, manually operated means for releasing the latch oi' the nrst push ring, `and means operated by the rst .push ring` for releasing the latch oi ram in the other direction, time controlled means c5 for limiting the movement of the first push ring,

by the first push ring for releasing the latch oi' the second push ring. l

17. In a welding apparatus, a casing including a centrally disposed hollow stud, a ram slidably mounted in the stud, rst and second push rings slidably mounted on the stud, the iirst push ring being resiliently connected to the ram for moving the ram in one direction and the second push ring being arranged to move the ram in the other direction, time controlled means for limiting the movement of the first push ring, means for limiting the associated movement of the ram, a power spring between the push rings, a .latch forirestraining movement or each push ring. manually operated means for releasing the latch of the rst push ring, and means operated by the rst push ring for releasing the latch of the second push ring.

18. In a welding apparatus, a casing, a ram slidably mounted in said casing, ilrst and second push rings slidably mounted in said casing and operatively connected to said ram, a power spring between the push rings, time controlled means for limiting the movement of the ilrst push ring, a latch for restraining movement of each push ring, manually operated means for releasing the latch of the rst push ring, means operated by the rst push ring for releasing the latch of the second push ring. and means acting in time with the manually operated means for closing the welding circuit.

19. In an apparatus i'or welding a stud to a plate, a casing, a ram including means for holding a stud and slidably mounted in the casing, a single power spring for moving the ram in either direction, first and second latches for controlling the application of the spring to the ram, manually operated'means for releasing the first latch toallow the spring to move the ram to separate the stud from the plate, and time controlled means acting in time with the manually operated releasing means for releasing the second latch to allow the spring to move the ram to engage the stud with the plate.

20. In an apparatus for welding a stud to-a plate, a casing, a ram including means for holding a stud and slidably mounted in the casing, a single power spring for moving the ram in either direction, ilrst and second latches for controlling theapplication oi' the spring to the ram,

manually operated means for releasing the nrst latch 4to allow. the spring to move the ram to separate the stud from the plate, time controlled means initiated by the manually operated releasm8 means for releasing the second latch to allow the spring to move the ram to engage the stud with the plate, and'means acting in time with the manually operated means Vfor closing the welding circuit.

EDWARD F. NELSON.