Welding machine

Application filed February 11, 1931. Serial No. 014,940.

In some welding machines spaced electrodes are secured together for unitary rotation in contact with metal to be welded, such as tubular metal blanks. Where the tubular S blanks are butt-welded the diameter of the electrodes may be similar, and where the tubular blanks are lap-welded one electrode must be of greater diameter than the other electrode when they are radially disposed 10 with respect to a tubular blank in order that _ both electrodes may contact with surfaces of invention; the blank that have different radii. The surface speeds of such two electrodes are different so that as both electrodes rotate at the 15 same speed, one electrode will more or less slip against the surface of the blank during rotation so that wear upon said electrode will be greater than the wear on the other electrode, thereby necessitating frequent dressing 20 of at last one of the electrodes. Furthermore, since one electrode will wear faster than the other electrode the best contact of both electrodes with the tubular blank is not at all times attained with consequent increase of 25 current consumption.

The object of my invention is to provide an electrical welding machine or transformer in which spaced electrodes of different diameters may be used, as in lap-welding of tubular so blanks, and in which the electrodes will be independently rotative so that neither electrode will influence the rotation of the other, whereby each electrode may rotate in contact with a corresponding portion of the tubular blank individually to avoid sliding contact therewith to reduce wear on the corresponding electrode due to its contact with the blank.

In carrying out my invention as illustrated I provide a transformer having spaced rotative electrodes in electrical circuit with the secondary of the transformer, one of said electrodes being secured to one portion of the secondary and the other electrode being rotatively connected with another portion of the secondary and free to rotate relatively thereto, whereby each electrode may contact with a given portion of a metal blank on opposite sides of a lap or seam to be welded and each electrode may rotate independent85 ly of the other as the blank is traversed in contact with said electrodes.

My invention also comprises novel details of improvement that will be more fully hereinafter said further and then pointed out· in gg the claims.

Reference is to be had to the accompanying drawings in which,

Fig. 1 is a side view partly in section, illustrating a rotary transformer embodying my

Fig. 2 is a sectional detail substantially on the line 2, 2 in Figure 1. »

Fig. 3 is a section on line 3, 3 in Figure 2. Fig. 4 is a detail plan view of Figure 3. Fig. 5 is a sectional detail of a modification, and

Fig. 6 is a face view of a unitary electrode.

Similar numerals of reference indicate corresponding parts in the several views.

My improvements are illustrated in connection with a transformer of the rotary type, such as set forth in Letters Patent to Snodgrass and Hunter No. 1,478,262, granted December 18,1923. The secondary of the transformer is indicated at 1, comprising a rotative body or shell having a face plate 2 electrically connected thereto and which may be integral with a tubular axial portion 3 that extends laterally from one side of the shell through and beyond the latter, and an outer cylindrical part 4 is spaced from the axial portion 3 and extends from the face plate 2. Ventilating openings 5 may be provided in the cylindrical part 4. Said parts may be cast in a single piece of metal. The opposite side of the secondary body or shell is provided with a plate 6, which may be secured to the annular part 4 by any desired means, such as by screw-threads at 7. The plate 6 has a bore at 6α of greater diameter than the portion 3 of the secondary to fit around and out of contact with the latter for insulating parts 3 and 6 from each other. At 8 is an annular electrode which may be made in a series of segments 8α having radial edges 85, preferably set in contact, as illustrated in Figure 2, or said electrode may be made in a single annular piece, as illustrated in Figure 6. The electrode 8 is

TO to

100

1,865,682 mounted upon and adapted to rotate independently with respect to a portion of the secondary of the transformer, being shown mounted upon the axially extended portion E 3α °f the secondary and in circuit therewith.

I have illustrated a metal sleeve 9 rotatively mounted on and in contact with the axial portion 3α of the secondary, and upon said sleeve 9 is mounted a metal support 10 to make elec1Q tncal contact with the sleeve 9. The sleeve 9 may be secured on the axial portion 3α by any desired means, such as by shrinkage or screws.

W electrode 8 is detachably connected with the support 10 and in electrical contact therewith. A ring 11 surrounds a portion of the support 10 and is detachably secured thereto. I have , shown screws 12 passing through holes 13 in the ring 11 and meshing 2o m threaded apertures 14 in support 10 for detachably securing the ring to said support, lhe electrode is shown provided with recesses 15 into which plugs or studs 16 enter, which plugs extend through holes in the ring 11 25 ior securing the electrode 8 upon an annular seat 10α of the support 10. The plugs are shown tapered at their inner ends to engage walls of the recesses 15 to force in into contact with the support

10. The support 10 is shown provided with an angularly disposed face 10δ against which a corresponding angular face 8' of the electrode is adapted to. bear, whereby said faces meet in a wedge-like manner for securing 36 the electrode electrically against the support 10. By making the electrode 8 in several segments, as illustrated in Figure 2, the electrode segments may be readily removed ana replaced, which will be found particu40 larly advantageous when the electrode is ^US π ^{xor we}^ⁿg pipe or tubes of heavy gauge walls and large diameters. If preferred, however, electrode 8 may be in a single piece of metal adapted to be secured to the sup45 port 10 in manner described by utilizing the ring 11 and the plugs 16.

In Figure 5, the recesses 15 are shown tapering to receive the correspondingly tapered ends of the plugs 16, whereby the electrode 50 segments, or the unitary electrode, may be positively secured by said plugs.

In order to provide good electrical contact between the support 10 and the sleeve 9 any desired number of brushes 17, of any well55 known material, such as carbon or wire mesh, are slidably located in bores 18 in the support 10 to contact with the sleeve 9 (Figs. 1 and. 3). Said brushes are normally pressed against sleeve 9 by springs 19 located in said ⁰⁰ bores and bearing against said brush and⁷against threaded plugs 20 in said bores. Said brushes may be removed and replaced conveniently, as desired, by means of the construction described. ~ The sleeve 9 is replaceable to accommodate for wear of the brushes

17, as distinguished from causing the brushes to contact with the axial portion 3α.

An electrode 21 is electrically connected with a. second side of the secondary, being shown in electrical connection with the plate 70 6 of the secondary. Electrode 21 may be similar to the electrode 8, that is to say, it may comprise several sections, or be in a single piece, as previously described. I have shown a ring 22 provided with screws 23, to secure 75 said ring to the plate 6 in manner described with respect to the screws 12, and plugs 24 carried by the ring 22 to enter recesses 25 in the electrode 21, in manner described with respect to the electrode 8. The plate 6 is 80 shown provided with an extension 6' upon which the electrode 21 and the ring 22 are applied. The electrode 21 is shown provided with an inclined face 26 engaging a correspondingly inclined face 27 projecting from 85 the part 6', whereby said electrode is secured to said face 27. The support 10 and the projecting portion 6' of the secondary are spaced apart and the electrodes 8 and 21 are also spaced apart, insulation 28 of any suitable 00 character preferably being interposed between the parts 10, 6', 8 and 21.

I have illustrated the part 6' of the secondary in the form of a jacket extending from the plate 6 adapted to contain cooling 05 water for the electrode 21. I have also illustrated a hollow jacket 29 upon the extended axial portion 3α of the secondary adapted to contain cooling water, the said jacket 29 being in contact with the support 10, as illus- io^;·trated in Figure 1. A nut 30, on extended part 3α, is adapted to bearing against jacket 29 to retain the latter in position. The flange of sleeve 9 and the nut 30 retain the parts 10 and 29 from sliding axially. 105

Cooling water may be supplied through a pipe 31 to a tube 32 and thence into jacket 6', and from said jacket through a tube 33 to a water space 34, from which a tube 35 extends and communicates with jacket 29, no and a tube 36 provides communication between jacket 29 and an outlet passage 37, plugs 38 and 39 closing the passage. The details of the cooling arrangements described are substantially the same as those set forth 115 m my application Serial No. 441,784 filed April 5, 1930.

The secondary is shown secured to a member 40 carried by shaft 25 that supports the secondary, the secondary and the member 120 40 being shown insulated at 41 and secured together by screws 42 insulated from said member. The primary 43 of the transformer is shown comprising a core 43α and winding 43δ within the chamber 2α of the secondary 12. body or shell. The terminals of said primary are connected to collector rings 44 and 45 that are carried by and insulated from the body 2 insulated screws 46 connecting the collector rings to said body. Alternating current is igo

1,865,532 led to the collector rings from any desired source by brushes 47. The member 40, the collector rings, and the brushes,maybesimilar to corresponding parts set forth in the afore⁵ said Letters Patent. The shaft 25 may be journaled in a frame 48 in any desired way. As illustrated the secondary body or shell 2 and its axial extension 3α are mounted upon a tube 49 within the bore of the parts 3 and ¹⁰ 3α. The tube 49 is mounted upon an insulating sleeve 50 located in said tube and upon shaft 25.

At A is indicated a tubular metal blank whose margin or edge portions are to be weld¹⁶ ed together. The tube may be guided for contact with the electrodes 8 and 21 in any desired or well-known way, such as by means of rollers 51 suitably spaced apart and carried by studs or shafts 52, any suitable or ²⁰ well-known means being provided for traversing the blank A along the electrodes at desired speed. In the example illustrated in Figure 1, the marginal portions a and a' are lapped and the electrodes bear upon the blank ²⁶ on opposite sides of the joint at said lap, whereby when electric current flows from the secondary through said electrodes it will traverse the blank at the lap for heating the portions a and a' to a welding heat for welding ³⁰ said lapped portions together. Both of the electrodes will rotate by reason of contact with the tubular blank as the latter travels. By reason of the lapping of the marginal portions of the blank the radius of the inset ³⁶ portion a is less than the radius of the portion a’ and the diameter of the electrode 8 is greater, to contact with the portion a of the blank than the diameter of the electrode 21 that contacts with the outer portion a' of ⁴⁰ the blank.

Since the electrode 8 may rotate independently or individually with respect to the rotation of the electrode 21, (which rotates at the same speed as the transformer), each elec⁴⁵ trode may rotate in contact with the corresponding portion of the blank A without regard to the rotation of the other electrode, since the electrodes have a common axis and 60 are spaced apart relatively to the lap or joint ^u of the metal blank between them. Said electrodes may rotate at different surface speeds, each electrode rotating individually with respect to the other according to the diameter . 55 of the electrode, whereby one electrode does not control the rotation of the other and thereby slippage of one electrode in contact with the metal blank caused by rotation of the other electrode does not occur as does occur 60 where two rotary electrodes of different dix ameters are secured together to rotate as a unit in well known types of lap-welding machines. By the means described wear upon the surface of each electrode will be in con⁶⁵ formity with its operation as an independent electrode, and undue wear on the contacting surface of the electrode 8 is eliminated.

While I have illustrated my improvement in connection with a transformer of the rotary type, in which the primary and second- W ary rotate together for supplying current to the individually operative electrodes on a common axis, it will be understood that current may be supplied to said electrodes in any other well-known or desired way. 75

Although I have illustrated my improved electrodes individually rotative on a common axis one electrode having a greater diameter than the other electrode, it will be understood that spaced electrodes on a common axisunay ⁸⁰have substantially the same diameter' with the advantage that neither electrode will control the rotation of the other, whereby inequality in the stock to be welded will hot .affect the rotation of the electrode not sub- ⁸⁵jected to such inequalities, which might occur were the two electrodes secured together to rotate as a unit, such as in butt-welding of heavy gage stock.