US2370485A - Electric welder - Google Patents

Description

Feb. 27, 1945.

C. A. NICHOLS ELECTRIC WELDER Original Filed April 9 1941 6 Sheets-Sheet l I 1 I l l H- I INVENTOR [bar/es H. Maimls Mn ATTORNEYS 6 sheets-sheet 2 Original Filed April 9, 1941 4 W 5 n w i 0 firs 1w m #n I M. m W m mfi m H I rv m w .7 M as 5 4 n 5 0 5 oo o OO a 1|...\ 0

Feb. 27, 1945. .A.N|H 3Ls 2,370,485

ELECTRIC WELDER Original Filed April 9, 1941 6 Sheets-Sheet 4 INVENTOR [barks H Mzbals 4114440 M 1 A. ATTORNEYS Feb. 27, 1945.- c. A. NICHOL S 2,370,

ELECTRIC WELDER Qrigi nal Filed April 9, 1941 6 Sheets-Sheet 5 mmg nhnn Feb. 27, 1945 c. A. NICHOLS 7 8 ELECTRIC WELDER 7 Original Filed April 9, 1941 6 Sheets-Sheet 6 3 Q ITWI HHI I J mu INVENTOR $42 ATTORNEYS Patented Feb. 21, 1945 1 2,370,485

ELECTRIC WELDER Charles A. Nichols, Anderson, Ind., assig'nor to General Motors Corporation, Detroit, Mich, a. corporation of Delaware Original application April 9, 1941, Serial No.

387,585, now Patent No. 2,293,846, dated August Divided and this application March 8, 1942, Serial No. 433,597

2 Claims.

This invention relates to the manufacture of electrically welded steel tubing and is a division of Serial No. 387,565 filed April 9, 1941, now Patent No. 2,293,846.

The object of the invention includes the pro- 5 tatable but can not move, axially with respect vision of an improved electric welding machine to bracket 40A. Shaft 41, which is made of pure of simple and durable construction which may copper, is mounted upon shaft 50 also of pure be manufactured at low cost. copper and is insulated therefrom by non-con- Further objects and advantages of the present ducting member including a sleeve Bi of lamiinvention will be apparent from the following denated Bakelite tubing. scription, reference being had to the accompany- Shaft 41 is provided with stainless steel inserts ing drawings wherein a preferred-embodiment of 52 for receiving screws 53 by which welding electhe present inventionisclearly shown. trode I4 is attached to shaft i1 and is electri- In the drawings: cally connected therewith. Likewise shaft 50 is 1 is a side elevation partlyin section provided with stainless steel inserts 55 for receivshowing aweldlng machine embodying tihe presing screws 56 by which welding electrode 51 is ent invention; attached to the shaft 50 and is electrically con- Fis. 2 is a view taken in the direction of the nected therewith. A circular plate of insulation arrow 2 of Fig. 1, and is partly in'section; -58 separates the welding electrode discs 54 and Fig. 3 is a view taken in the direction of arrow 51 which are made of forged copper. Each disc 80f Fig. 1; is provided with a number of concentric circu- Fig. '4 isaplan view; lar grooves 59 in order to increase the radiating Figs. 5 and to provide a fragmentary longisurface. Streams of water play upon these tudinal sectional view on the line l-J of Fig. 4 grooves in order to cool the electrodes. and is drawn to a larger scale than Fig. 4; 28 Screws 82 secure to the bearing bracket 403 Fig. 6 -is a longitudinal sectional view of the transformer of which a fragmentary sectional view appears in Fig. 5; and

Fig. '1 is a sectional view on the line 1-1 of Fix. 6.

The apparatus comprises a box-like base "of Fig. 1 provided with a door II in the left wall thereof. Referring also to Fig. 2 the base 2|! supports four tubular bearings 22 for guiding vertically movable rods II, the lower ends of which are attached to a spider it, provided with nuts I! for receiving screws 28 provided by shafts 21 attached to worm wheels 20 supported by step bearings 21 (Fig. 1), resting upon the top of the base II. Worm wheels 28 mesh with worms 10 connected with a shaft v3i supported by bearing brackets 82 attached to the underside of the top of the base 20. Shaft Ii has a squared end 18 (Fig. 2) for receiving a handwheel 34 (Fig. 1). By turning the handwheei N the rods 23 may be raised or lowered in order to vary the elevation of the welding electrodes to be described.

The rods 2| support a frame ll insulatingly supporting at its ends bearing brackets A and "B. Mlcarta insulating plates "X space the brackets "A and B from frame ll. Bracket A supports ball hearing; I (Fig. 5) which are secured between retainer. plates 42 and. ti se-' cured to a ring I which is fixed to the annular The inner races of the ball bearings ii are clamped together and are confined between'a shoulder It of a tubular shaft 41 and a nut 48 threaded on said shaft. Shaft 41 is freely robearing retainers 80 and BI between which a pin or small diameter roller bearing 63 is confined. The inner race 84 of which has a snug sliding fit with a reduced portion 65 of shaft 50. Thus,

0 bearing 83 supports the right end of the shaft 50 but permits longitudinal movement thereof due to expansion and contraction with changes in temperature. The length of the shaft 50 between the bearing brackets A and 40B is relatively long therefore there will be an appreciable amount of expansion and contraction. But, practically all of this expansion and contraction takes place between the bearings 4i and 63. As the distance between the bearing 4| and electrodes 54 and 51 is relatively short the expansion of the shaft between the bearings and the electrode is practically negligible. I

A disc of pure copper 10 is attached by screws 'll'to the flange 12 of shaft 41. The disc and shaft are electrically connected by screws ii and by pins Ha insulated fromand drivingly connected with flange 60a ofshaft 50. Disc 10 is insulated from shaft 50. Shaft supports and is electrically connected with a disc of pure copper 13 mechanically and electrically connecting with the disc 10 by'rods H of pure copper secured in position by copper-nuts II. The space between the discs 10 and I3 and between the shaft 50 and the rod 14 is occupied by a cylindrical,

bearing boss ll integral with the bracket "A. s laminated transformer core I! and a transformer primary 'l'l comprising a plurality of four-layer turns of flexible copper ribbon separated by insulating ribbons I9. The core I is suspended from the rods I4. As shown in Fig. 'I the core extends through two a uminum spiders 80 of annular formation and integral with lugs 8|, spaced 90, and each provided with a socket 82 at its outer end for receiving a set screw 83 passing through a threaded hole in a rod I4. The primary and core assembly are insulated from-the discs I0 and I3 and from the shaft 50 by nonconducting-plates 85 and 88 and non-conducting sleeve 8?.

The ends of primary H are connected by leads 80 and ill with copper rings 02 and t3, respectively, insulatingly supported by a sleeve 9% and clamped thereon by a nut 95. The rings 02 and 93 are insulated from each other from the sleeve, from the nut 95 and from a spacer 96. Sleeve 94 is connected with shaft 50 by a key 9'1. The sleeve 94 is split by saw-cut at 98 and by saw-cut at 99 to provide a resilient clamping portion I00 cooperating with screws IOI which cause this clamping portion to grip the shaft 50. The secondary of the transformer is a single turn circuit comprising electrode 51, shaft 50, disc I3, rods 10, disc 10, shaft 41 and electrode 04.

Each collector ring 92 and 93 is engaged by two brushes I02 guided by brush holders I03 and urged by springs I04 into ngagement with their respective collector rings. The brush holders by the electrodesand the groove provided by the roller IIO are shaped so as to accommodate the tubing which is slightly elliptical so that the tubing is welded out of round after having been formed out of round. .As disclosed in the Nichols I always be moved into contact with the scarfing tool. Even after all of these precautions are taken to prevent skewing or the tubing, it some times happens that the tubing will spiral slightly thus displacing its seam from the vertical plane midway with the electrode. 1 have discovered that such spiralling may be eliminated by slightly angularly displacing the plane of rotation of the central groove of roller ill! from the plane of rotation of the median line of insulation sheet 58. This is accomplished by moving the plate I23 about a pin 930 having a threaded shank iSI receiving a nut I32 by which the pin I is attached to the table 20. The axis of the pin is vertical and is represented by the point I80X (Fig. 4) intersecting the median line IIIl-Y of the groove in roller H0 and passing vertically upward as indicated by line ISI-X (Fig. 5) and I03 are supported by brackets I00 insulated from each other and insulatingly supported by bearing bracket 4013. Each brush holder threaded part I00 threaded through the bracket I00 and engageable with a nut I01 for attachment of a terminal clip I08 connected with a cable I09.

As shown in Fig. 5, the tubing T to be welded passes between the welding electrodes 01 and 04 and a supporting or back-up roller IIO having a flange III engageable with only one electrode. The roller IIO which is made of copper is attached by screws II2'to the flange H8 of ashaft II4 Journaled in ball bearings IIO carried by forked lever II8 pivoted upon a pin I" (Fig. 2), supported by bracket [I8 integral with a tubular shaft supported vertically and iournaled for ro-. tation by tapered roller bearings (not shown which are supported by asleeve I2I attached to a bracket I22 which is carried by a horizontal plate I 23 resting on table 20. Roller H0 is caused to exert uniformly constant pressure upon the tubing T by the use of weights I24 attached by a cable I20 to lever IIO. While the roller H0 is thus exerting the desired constant upward force upon the tubing T to secure proper welding pressure between the tubing and the electrodes, the roller IIO cooperates with the tubing T in the manner of a trolley wheel with a trolley. In other words, the roller IIO follows the tubing T and takes whatever position the tubing T may require due to the minute variations in shape or diameter. This weldingm'achine is particularly adapted for welding small diameter steel tubing according to the method disclosed in the copending application of Charles A; Nichols, Serial No.-384,563, filed March 21, 1941. cessfully weld small diameter tubing it has been found expedient to form the tubing out of round in order that it may be guided by guide wheels having grooves similarly formed so that the seam of the tube will be always on top or in alignment with the insulation plate 08 between the electrodes -04 and 01. The grooves provided I08 has a intersecting the axis of the tubing '1' and the median line of the groove provided by the electrodes 00 and 01. This adjustment may be effected by turning adjusting screws I08 (Fig. 4) each threaded through a lug I34 attached to table 20 and engaging lug I30 attached to plate I 3.

During the continued use of the machine the tube-receiving groove provided by the electrodes becomes roughened and worn out of true due to the intense heat of the electric current passing 40 between the electrodes and the tubing. This groove may be trued or resurfaced by the use of a cutting tool I40 which is part of a groove cutting apparatus I4l mounted upon the bearing bracket 40-A. Before using the groove cuttin apparatus I the outer cylindrical surfaces of the electrodes are trued by a tool I02 mounted in a tool holder I43 of the conventional type also supported by thebearing bracket 40--A. While truing the electrodes they should be elevated above th roller IIO. Before frame 00 is elevated by turning the handwheel 04 (Fig. 1), a shaft I (Fig. 4) is turned by a wrench fitting on the squared end I40 thereof in order to move an eccentric cam under that portion of the lever IIO extending to the right of the bearing pin 1. The eccentric then receives the pressure exerted by weights I24 and upward movement of roller H0 is prevented while the electrodes are being elevated preparatory to trimming.

While the machine is welding tubing the electrodes are rotated by movement of the tubin T between them and the rollers H0. The tubing T is propelled'by th forming rolls which contact with the tube prior to welding and by the rounding or truing rolls which contact with the tube after welding. But, when the electrodes are being trued, they are rotated by a separate source of power comprising an electric motor I00 (Fig. I) mounted on a frame "I containing a gear reducing mechanism connecting the motor I00 with a shaft I02 attached to a pulley I03 connected by belt I04 with a pulley I00. Frame I-0I is supported by frame 40. Pulley I00 (Fig. l) is journaled on a bearing provided by retainer plate 0|. Pulley I00 (Fig. 3) pivotallysupports lg v. I

at I51 a plurality of pawls I58 urged by leaf springs I58 into engagement with a fine tooth ratchet I50 connected by keys I6I with the extension '65 of shaft 50 (Fig. 5). Leaf springs I59 are fastened to the heads of the screw I59a attached to pulley I55. During welding the ratchct I80 rotates counterclockwise (Fig. 3) and the teeth thereof merely move under the pawls I58 which ride upon them with light pressure. When the electric motor drives the pulley I55counterclockwise Fig. 3 motion is transmitted from the pulley to the. shaft 50 through the pawls I'5B the ratchet I58.

The ratchet I60, Fig. 5, is retained by a washer I62 and a nut I53 threaded in the shaft 50. The nut I53 is integral with a pipe coupling I64 welded to a tube I85 extending through a central hole I56 in shaft 50 and terminating near the plug Iil in the left end of the shaft 50, Fig. 5. Water for cooling the shaft 50 enters through a passage I68 and flows through the tube I65 and then back around the outside of the tube toward the right and out through a passage I69 in plug I53. Plug I63 includes an extension Ill! (Fig, 50), around which is swivelled a conventional two-hose fitting (not shown) having separated annular ducts cooperating with side inlet Ifla and side outlet I590: of the extension I10.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

what is claimed is as follows:

1. An electric welder comprising rotatable electrode discs spaced by insulation and together providing a groove for receiving a butt-seam tube to be welded, a transformer rotatable with the discs and including an assembly comprising an annular core and a primary winding upon the core, and including a secondary circuit comprising one electrode, a drive shaft connected therewith and extending through said core, the other electrode and a tubular member connected therewith and surrounding said drive shaft and extending to said transformer assembly, means electrically connecting said drive shaft and tubular member and encircling the core and primary assembly. and including detachable rods extending parallel to the shaft, means for rotatively supporting the drive shaft and tubular member, rings surrounding the core and fixed thereto, and members extending from certain of said rods and engaging said rings in order to support the core by said rods.

2. An electric welder comprising rotatable electrode discs spaced by insulation and together providing a groove for receiving a butt-seam tube to be welded, a transformer rotatable with the discs and including an assembly comprising a tubular core and a primary winding upon the core, and including a secondary circuit comprising one electrode, a drive shaft connected therewith and extending through said core, the other electrode and a tubular shaft connected therewith and surrounding the drive shaft and extending to said transformer assembly, means electrically connecting the drive shaft and tubular shaft, and including removable members having portions extending parallel to the drive shaft; means for rotatively supporting the shafts; tubular members surrounding the core and fixed thereto; and members extending from the parallel portions of the removable members for engaging the tubular member in order to support the core from the parallel portions of the means connecting the shafts.

' CHARLES A. NICHOLS.

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