US3092709A

US3092709A - Attachment for a wire or strip forming machine

Info

Publication number: US3092709A
Application number: US34798A
Authority: US
Inventors: Vogt Werner; Erman V Cavagnero
Original assignee: Torrington Manufacturing Co
Current assignee: Madison Management Group Inc
Priority date: 1960-06-08
Filing date: 1960-06-08
Publication date: 1963-06-04
Anticipated expiration: 1980-06-04

Description

ATTACHMENT FOR A WIRE OR STRIP FORMING MACHINE Filed June 8. 1960 June 4, 1963 w. voe'r ETAL 4 Sheets-Sheet 1 FIG. 4

INVENTORS WERNER VOGT ERMAN V CAVAGNERO 1:164. 1 2:: CM

ATTORNEYS June 4, 1963 w. voe'r ETAL 3,092,709

ATTACHMENT FOR A WIRE OR STRIP FORMING MACHINE 4 Sheets-Sheet 2 Filed June 8, 1960 June 4, 1963 w. VOGT ETAL 3,092,709

ATTACHMENT FOR A WIRE OR STRIP FORMING MACHINE 4 Shecs-Sheet 5 Filed June 8. 1960 FIG. 6

FIG. 8

June 4, 1963 w. VOGT ETAL 3,092,709

ATTACHMENT FOR A WIRE OR STRIP FORMING MACHINE Filed June 8, 1960 4 Sheets-Sheet 4 FIG /3 operation between the mandrel, the stripper rods, and the welding electrodes in the welding mechanism of FIG. 2.

FIG. 9 is an enlarged fragmentary view, partly in sec tion and partly in elevation, of the mandrel employed in association with the welding mechanism of FIG. 2.

FIG. 10 is a fragmentary side view of the welding mechanism of FIG. 2 showing the structure of the driving cam and the follower on the actuating leg of the operating lever.

FIG. 11 is an enlarged sectional view taken on the line 99' of FIG. 2 and illustrating the structure of the connecting means between the operating lever and the pull-rod.

FIG. 12 is a diagrammatic view illustnating the movements of the various parts of the welding mechanism of FIG. 2.

FIG. 13 is a perspective view of an article produced by the forming machine and welding mechanism of FIG. 1.

In the drawings wherein is shown a preferred embodiment of this invention, and first referring particularly to FIG. 1, a wire or strip forming machine of a type with which this invention may be associated is indicated at 20. The wire or strip forming machine 20, to be described below, is adapted to accommodate wire or strip of various types. That is, both the forming and feeding mechanisms of the machine are adapted to handle wire or strip having various cross-sectional shapes. In the description which follows, the machine is described in conjunction with the forming of a workpiece which is cut from a continuous length of wire having a flat or rectangular cross section. Such wire is often referred to as strip and this term will be used in the description which follows. However, it should be under-stood that the machine may also be adapted for forming workpieces from wire having various cross-sectional shapes. Accordingly, the term strip, as used through out the description, should be construed in a broad sense and equivalent to the term wire so as to refer to a continuous thread or slender rod of metal of any cross-sectional shape, such as round, square, triangular, fia-t or irregular.

The strip forming machine shown in FIG. 1 is of fourslide type, the forming mechanism thereof comprising four

slides

22, 24, 26 and 28 disposed in a hub-spoke arrangement about a central centerform or mandrel 30. The several slides are preferably movable in a vertical plane, as shown, and forming tools are provided on the ends thereof adjacent the mandrel 3%. Suitable cams move the several slides inwardly in timed relation to each other so that the tools thereon sequentially cooperate with the mandrel 30 to bend a workpiece around the mandrel to provide a product or article of a desired shape and form. Included in the forming machine is a feed mechanism, indicated generally at 32, which is operated by suitable cams and functions to feed the strip 34 transversely of the mandrel and into the zone of action of the forming tools and into the other various parts of the machine in proper timed relationship with the operation of said forming tools. Before entering the feeding mechanism 32, the strip 34 passes through a straightener 36 which is shown at the left in FIG. 1. Also included in the machine is a cam-actuated vertical cutoff device 3 8 which is disposed at the left of the slide 22 and which operates to cut the strip 34 into workpieces of proper length. That is, after the several slides are operated to form an workpiece around the mandrel 3t) and the formed workpiece is removed from the mandrel, the feeding mechanism 32 is operated to move the strip 34- a predetermined distance to the right and thereafter the cutoff device 38 is operated to cut from the righthand end of the strip a workpiece which is formed by the tools during their next sequence of operation. After the workpiece is cut from the strip 34, and before the several slides are operated to bend the same, the work- 4- piece is held against the mandrel by a cam-actuated stock clamp 40 which extends through the slide 22.

A cam or eccentric-actuated vertical press 42 is shown as being included in the machine 24 but the provision of such a press is optional. The press 42, when provided, may be used to perform preliminary operations, such a perforating, on the strip 34-. In the present case, the press 42 is employed to stamp the manufacturers name and other identifying indicia on the strip. Such presses are, of course, most advantageously used in the forming or stamping of flat stock.

The forming machine of FIG. 1, as mentioned previously, is operable in fixed cycles with one article being formed within each cycle. Generally, the mode of operation is such that one phase or fraction of each cycle is devoted to feeding the strip 34- into the machine and another phase of each cycle is devoted to the operation of the various slides. The vertical press 42 is generally operated during the forming phase. The feeding and forming phases consume practically the entire time of each cycle although a small portion of each cycle is devoted to ejecting the formed workpiece from the mandrel 30. While the details of the operating means for the machine may be widely varied, the machine in this instance is shown as including an electric motor 44 which supplies power for operating all of the various parts of the machine. The motor 44 is supported on a main frame 46 of the machine and turns a countershaft 48 through a belt drive indicated generally at 50. The countershaft 48 is suitably journaled in the machine frame 46 and carries at one end a gear 52 which drives another gear 54 secured on a lower horizontal longitudinally extending cam shaft 56. The cam shaft 56 also carries a cam which is indicated generally at 58 and which actuates the lower vertically movable slide 28.

At the ends of the lower horizontal cam shaft 56, there are fixedly mounted

bevel gears

60, 60. The

bevel gears

60, 60 respectively drive a bevel gear 62 secured on the lower end of a left-hand vertical cam shaft 64- and a bevel gear 66 secured on the lower end of a right-hand vertical cam shaft 68. The left and right-hand vertical cam shafts 64 and 63 are suitably journaled in the main frame 46 of the machine and each of said cam shafts carries a cam, said cam being indicated generally at 69 and 70, respectively. The cam 69 on the left-hand vertical shaft 64 actuates the left-hand horizontal movable forming slide 24 and the cam 70 on the right-hand vertical shaft is similarly operatively associated with the right-hand horizontal movable forming slide 26.

At the upper end of the right-hand shaft 68 there is secured a bevel gear 72. The gear 72 drives another bevel gear 74 secured at the right-hand end of an upper horizontal longitudinally extending cam shaft 76. The cam shaft 76 carries two cams, indicated generally at 78 and 80, which respectively actuate the upper vertically movable forming slide 22 and the cutoff device 38. When a forming press 42 is included in the machine 20', there is an additional cam or eccentric 82 on the shaft 76 for operating the press. Also, to the right of the cam 78 there is provided another cam 84 which actuates a bell crank 86 for operating the stock clamp 40.

The right-hand vertical cam shaft 68 also serves as a driving means for the welding mechanism to which the present invention more particularly relates and includes a cam 88 for this purpose. The said welding mechanism is shown mounted on the bed 90 of the machine at the right-hand end portion thereof, as shown in FIG. 1, and is indicated generally by the reference character 92. As will be described more fully hereinafter, all of the principal mechanical parts of the mechanism comprise a unitary assembly adapted to be detachably connected to the machine bed 90. Therefore, as a result of the manner in which the mechanism parts are supported on the bed of the machine, the mechanism may be readily removed from or incorporated in the wire or strip forming machine, as

required, for the particular product being manufactured by the machine.

As will also be brought out in more detail below, the welding mechanism 92 is generally intended for use in conjunction with the machine when the workpiece operated on by the forming tools is bent thereby into a looped or closed shape around the mandrel so as to have its two ends brought into juxtaposed relation and when it is desired that the juxtaposed ends of the workpiece be buttwelded together. The operation of the welding mechanism is such that this welding may take place during the time that another workpiece is fed and formed by the machine. Preferably, the mechanism cooperates with a portion of the mandrel 39 in such a manner that the mandrel supports the workpiece to be welded in proper relationship with the mechanism. It is contemplated, however, that in some instances the welding mechanism may be operated without use of a mandrel for supporting the workpiece therein. In fact, it is also contemplated that the basic parts of the mechanism 92 may be used in cooperation with the machine 20 for purposes other than welding. For example, the welding electrodes hereinafter described may be replaced with suitable forming tools to adapt the mechanism for performing a secondary forming operation on the workpiece rather than a welding operation. That is, the mechanism as described below functions to exert a clamping action on the workpiece and this clamping action could be used in performing operations other than welding. Therefore, although the mechanism 92 has been termed a welding mechanism and will be described as such, it should be understood that in its broader aspects it is not necessarily limited to the function of welding.

Referring now to FIG. 2 for a detailed description of the welding mechanism 92, it will be noted that this mechanism includes two generally parallel upright arms or

jaws

94, 94 which are pivotally supported adjacent their lower ends for swinging movement in a common plane normal to the mandrel 30. Two

welding electrodes

96, 96 are connected respectively with the

arms

94, 94, as described more fully below, and the arms are arranged that the electrodes are located on opposite sides of the mandrel, as shown, and in opposing relationship with each other. The swinging movement of the arms permits the electrodes 96, as to be moved to a spread-apart relationship at which a formed workpiece 97 may be positioned on the mandrel between the electrodes and to a closed relationship at which the electrodes clamp the workpiece between themselves. FIGS. 2 and 3 show the electrodes in their closed or article-clamping relationship. As shown most clearly in FIG. 2, and discussed in more detail below, the electrodes include dies 98, 98 on their respective opposing ends, the dies being the elements which actually engage and clamp the workpiece 97. During the welding process electrical current is passed between the electrode dies 98, 98 and through the workpiece 97 to heat the opposed ends of the workpiece to the fusion temperature. This heating, together with the mechanical pressure applied to the ends of the workpiece, then causes the two ends to become welded together.

The pivotal mounting of the

arms

94, 94 is provided by a frame, indicated generally at 99, which is detachably connected with the machine bed 9%. As shown best in FIGS. 4, 5 and 7, the frame 99 comprises two

side pieces

100, 100 spaced apart longitudinally of the machine bed 90, a bottom piece 101, and front and

rear pieces

102 and 104, respectively, which are spaced apart transversely of the machine and held some distance away from the machine bed 9% by the side pieces 104 100. As shown, this particular frame construction provides for accommodating the lower vertically movable slide 28 between the side pieces 1% with the main portion of the frame being located in front of the slide. The two

arms

94, 94 have their lower ends positioned between the front and rear pieces 102 and 104- 'respectively and are pivotally connected therewith by means of two journal pins 1%, 166 each of which pins has its opposite ends respectively secured to the pieces 1692 and 104, the arms 9d, 94 being free on the

pins

106, 106 so as to be angularly movable with respect to the frame. The frame 99 may be detachably secured to the machine bed in any conventional manner but in the present case is shown to be connected therewith by a plurality of

bolts

108, 198 which extend through flanges in the side pieces 1G0, and are threadably received by the machine bed 90. The frame 99 may therefore be readily removed from the machine by removing the

bolts

108, 108.

For purposes hereinafter described, the swinging movement of the

arms

94, 94 about the pivot axes provided 'by the journal pins 106, 1% is limited by stop means so that each of the arms is capable of moving through only a fixed angular range between two end positions so as to provide for a definite maximum and minimum spacing between the

electrodes

96, 96. The particular stop means provided with the

arms

94, 94 may take various forms; however, they are preferably adjustable to permit the range of travel of each arm to be shifted as desired between different end positions. In the illustrated embodiment of the invention the stops are shown to consist of four bolts fill, 112, 114- and 116 which are threadably received in various portions of the frame 99, as shown in FIG. 2, in such a manner that the inner ends of the bolts are engageable with portions of the arms 94, 9 5 for limiting their movement, each of the bolts having a locking nut associated therewith, as shown. Referring to FIG. 2, the stop bolt 11th is engageable with the lefthand arm 94 to limit its movement in the counterclockwise sense, While the stop bolt 112 is engageable with a foot portion 118 of the same arm to limit its movement in the clockwise sense. Similarly, the right-hand arm 94 has a foot portion 120 which is engageable with the locking bolt 116 to limit the movement of that arm in the clockwise sense and which foot portion is also engageable with the bolt 114 to limit the movement of the righthand arm in the counterclockwise sense. All of the bolts 1.10, 112, 114 and 116 are, of course, adjustable relative to the frame to vary the limits of the movement of the arms.

The

welding electrodes

96, 96 of the

arms

94, 94 are so arranged as to cooperate with a portion of the mandrel 3b which is located out of the range of the forming tools on the

slides

22, 24, 26 and 28. This enables the Welding mechanism to be operated in a sequence of movements which are basically independent of the sequence of movement of the forming tools and without interfering with the tools. As will be best seen in FIGS. 5 and 8, the mandrel 30 is fixedly secured by conventional means to the bed 96 of the machine so as to project outwardly therefrom. That part of the mandrel which projects from the machine bed includes a rear portion 122 at which the workpiece is formed by the sequential operation of the slides and a forward portion 124- at which the workpiece is later welded. In FIG. 5 only the lower slide 28 is shown, while in FIG. 8 the two horizontally

movable slides

24 and 26 are shown somewhat schematically. The tools on the four slides cooperate with the workpiece and with the rear mandrel portion 122 to bend the workpiece into the desired shape around the rear mandrel portion 12-2 while the workpiece remains at the same axial position on the rear mandrel portion, and the rear mandrel portion has a periphery which generally corresponds in size and shape with the inside surface of the workpiece. The workpiece can, of course, be bent or shaped into many different shapes or forms by the use of different tools and mandrels. However, in cases where the workpiece is to be later welded, the shape of the formed workpiece is such that its two ends are brought into opposing or juxtaposed relationship so that they may be later pressed together and united by the welding process. In the present instance, for example, the mandrel and forming tools are shown to be adapted to produce a product such as that shown in FIG. 13 and indicated generally by the reference character 126. The article or product shown at 126 is intended for use as a hose clamp and, as shown, has its two

ends

128, 128 located in opposed relationship and butt-welded together as at 136. The article 126' is similar to the formed workpiece indicated at 97 in FIGS. 3 and 8 except that the workpiece 97 does not have its opposed ends 128, 128 welded together.

After a workpiece is formed or bent into the desired shape at the rear portion of the mandrel, it is moved to the forward mandrel portion 124 by suitable means such as a pair of

stripper rods

132, 132 as shown in FIG. 8. When stripper rods are used for fulfilling this function they are located and movable in corresponding openings in the machine bed located on opposite sides of the mandrel 30. During the feeding and forming phases of the machine operation, the stripper rods are held in a retracted position at which the forward ends thereof are located behind the forward surface of the machine bed as shown by the broken lines of FIG. 8. After the completion of the forming phase, however, the stripper rods are moved outwardly from the machine bed to push or slide the formed workpiece along the mandrel from the rear portion 122 to the forward portion 124, the forward extent of the rod being shown by the solid lines of FIG. 8. In moving the formed workpiece 97 to the forward portion of the mandrel, the stripper rods bring it into proper relationship with the

welding electrodes

96, 96 for the performance of the subsequent welding operation. It will be apparent from FIG. 8 that as one that as one workpiece is moved to the forward mandrel portion the work-piece which previously occupied such position will be pushed off of the mandrel so as to be discharged from the welding station. For the purpose of guiding a welded article from the mandrel, a wire 134 is ttached to the mandrel and leads to a receptacle, not shown, for receiving the welded products. The movement of the

stripper rods

132, 132 is effected by suitable cam or eccentric means which is driven from one of the cam shafts, such as the cam shaft 56, so that this movement is effected in timed relationship with the movements of the forming tools and of the welding mechanism 92. As mentioned previously, the stripper rod movement is so adjusted as to occur at the end of the forming phase and before the feeding phase which initiates a new machine cycle. The feeding cycle of the next phase, however, may start somewhat prior to the time the stripper rods are brought back into their fully retracted positions so that a new workpiece is fed to the mandrel while the stripper rods are being retracted.

The forward mandrel portion 124 is located between the

electrodes

96, 96 of the welding mechanism and supports the formed workpiece in proper relationship therewith. FIG. 3 shows a workpiece 97 located on the forward mandrel portion and clamped between the

electrodes

96, 96. From this figure, it will be noted that the forward portion 124 of the mandrel has a periphery which corresponds generally in size and shape with the inside surface of the formed workpiece, and that the

electrodes

96, 96 are provided with working faces that conform with and engage at least a part of the outer surface of the workpiece. Adjacent the juxtaposed ends 128, 128 of the workpiece the forward mandrel portion 124 is relieved or cut away so as to leave the juxtaposed ends unsupported and capable of being squeezed together to some extent during the welding process to cause the material thereof to be upset after it is heated to the proper welding temperature. In the present instance, the formed workpiece 97 is of such a shape as to have an upper rib and a lower rib and the rear portion 122 of the mandrel is accordingly provided with an upper rib 136 and a lower rib 138. The forward mandrel portion 124 includes the upper rib 136 but lacks the lower rib 138, this lack of the lower rib providing for the relief which permits the juxtaposed ends of the workpiece to be upset by the clamping action of the electrodes during welding. As indicated in FIG. 9, the forward mandrel portion 124 is made from an electrical insulating material, such as micarta, and is secured to the rear, metallic portion 122 by a connecting bolt 140. The guide wire 134 is connected to the bolt by welding or other suitable means.

Various means may be employed for connecting the

electrodes

96, 96 to the

arms

94, 94 but it is preferred that whatever means is used it be such as to permit the electrodes to be adjusted transversely of the mandrel 30 and to permit the same to be readily removed from the arms and replaced with other electrodes to adapt the mechanism to be used with workpieces of a different shape. Also, after extended use the

electrodes

96, 96 may become burnt or eroded so that they should be readily removable from the arms for dressing or replacement if more of the same type of workpieces are to be welded. In the illustrated mechanism, each electrode includes a die 98, which is preferably made from hard copper, and a shank member 144 to which the die is preferably detachably secured by a plurality of screws 146, as shown in FIG. 2. Also, as shown in FIG. 3, each of the dies 98, 98 is provided with an insert 147 of elkonite or similar material adjacent the location at which the welding die engages the opposed ends of the workpiece and at which the greatest welding pressure is applied during the welding process.

The shank portion 144 of each electrode 96 is connected to the associated arm 94 by two

bolts

148, 148. Referring to FIG. 6, it will be noted that the shank member 144 has a recessed face 150 which generally corresponds to an opposing face 152 on the arm 94 so as to provide a tongue and groove relationship between the shank 144 and the arm 94 which permits the shank to be slidably moved with respect to the arm and in a transverse direction with respect to the mandrel 3t Suitable electrical insulation 154 is provided between the opposed faces of the shank and the arm and corresponds generally in shape to the shape of the faces 150 and 152. The left-hand arm 94, which is shown in FIG. 6, also includes a terminal piece 156 to which the laminated bus bar 158 is connected by means of clamping plate 160 and bolt 162. The terminal piece 156 engages the outer face of the shank 144, and both the terminal piece and the shank are provided with elongated slots for receiving the

bolts

148, 148 so as to allow both the shank and the terminal piece to be moved transversely relatively to the arm. As shown in FIG. 6, the

bolts

148, 148 are insulated from the terminal piece 156 by a strip 164 of insulating material and pass through the terminal piece and the shank without engaging the same so as to be further insulated from these p eces by the air gap existing between the bolts and these pieces. The connection between the left-hand electrode in FIG. 2 and its arm 94 is generally similar to that shown for the right-hand electrode in FIG. 6 except that the terminal piece 164 for connecting the bus bar 166 to the lefthand electrode is of a somewhat different shape from the right-hand terminal piece 156, as shown in FIG. 2.

To aid in adjusting the

electrodes

96, 96 transversely of the mandrel 30, each of the

arms

94, 94 has associated therewith an adjusting screw, the adjusting screw associated with the left-hand arm being indicated at 167 and the adjusting screw associated with the right-hand arm being indicated at 168. The inner end of the screw 167, as shown in FIG. 2, engages a depending portion of the lefthand electrode 96 to limit its movement to the left, while the head of the adjusting screw 168 engages a similar depending portion on the right-hand electrode 96 to limit its movement to the right. To adjust the electrodes 96,

96 on the

arms

94, 94, the

bolts

148, 148 are loosened to the point where the

shanks

144, 144 are only slightly frictionally restrained thereby against movement relative to the arms. The adjusting bolts 167 and 168 are then turned to move the electrodes inwardly toward the mandrel to the desired positions and then the

bolts

148, 148 are again tightened.

Since the

electrodes

96, 96 attain relatively high temperatures after continued use, it is preferred that they be cooled to prevent excessive burning of the welding dies and to help cool the workpieces after they are Welded. In the present case, the electrodes are shown to be cooled by means of water which is supplied to and removed from the electrodes by conduits 171i, 176, as shown in FIG. 2. As shown in FIG. 6, the shank portion 144 of each electrode 96 is provided with a passageway 172 for conducting the cooled water through the electrode.

Electrical current of proper voltage and amperage to heat and weld a workpiece is supplied to the

electrodes

96, 96 by the bus bars 168 and 166 which are preferably of laminated construction and are sufficiently flexible to allow for the opening and closing movements of the electrodes. One feature of this invention, however, is that the movements of the electrodes are relatively small so that the bus bars may be made relatively short to minirnize the inductive losses of the electrical system. The outer ends of the bus bars 158 and 166 are connected to the

electrodes

96, 96 through the

terminal pieces

156 and 164, respectively, and are connected at their inner ends to a transformer 174 which is suitably mounted on or near to the machine Ztl. The operation of the trans former 174 is controlled by a suitable electronic control means which forms no part of the invention, such control means being presently commercially available from various suppliers. The operation of the control cabinet or panel is synchronized with movements of the

electrodes

96, 96 by one or more microswitches operated by a cam on one of the cam shafts of the machine 20. The control panel includes a timer which controls the amount of time allotted to the various welding steps performed on each of the workpieces. For example, the welding of each workpiece requires first a heating of the adjacent ends to the proper welding temperature, second, an upsetting of the workpiece material adjacent the opposed ends so as to form a firm bond between the two ends, and third, a cooling period which allows the welded area to attain a sufficiently low temperature so that the weld will not come apart or be stretched by the tendency of the workpiece to return to its original shape after the welding or clamping pressure applied by the electrodes is removed.

The movement of the electrodes between opened and closed positions with respect to the mandrel 30 is achieved by a novel linkage arrangement driven from the cam 88 on the cam shaft 68. As shown best in FIG. 2, this linkage includes the two

arms

94, 94, an operating lever 176 and a pullrod 178. The operating lever 176 is pivotally connected to the upper end of the right-hand arm 94, as by a pin 130, and includes a depending leg 182 and an actuating leg 184. The operating lever 176 is swingable about the pivot pin 180 in a vertical plane. The outer end of the actuating leg 184 is provided with a roller or follower 186, FIG. 10, which rides in the cam track v188 of the cam 88 so as to swing the lever in proper timed relation to the movement of the cam shaft 68 and to the movement of the other parts of the machine 20. A support 190 through which the actuating leg 184 of the lever extends is provided to restrain the leg 184 against movement in a direction normal to the machine bed, the opening of the support 1911 through which the leg 184 extends engaging both the front and rear faces of the leg for this purpose.

The left-hand end of the pullrod 178 fits into a recess 192 of the left-hand arm 94, as shown in FIG. 5, and is pivotally connected to the arm by a pivot pin 194, as shown in FIG. 2. The pullrod 178 etxends from the pivot pin 194 and through an opening in the right-hand arm 94. The left-hand end portion of the pull rod 178 which extends to the right of the right-hand arm is connected with the depending leg 182 of the operating lever 176.

The connection betweeh the depending lever leg 182 and the right-hand end portion of the pullrod is such that the lever leg may move with both a pivotal and lost motion movement with respect to the pullrod. A suitable biasing means, however, normally resists the lost motion movement and is effective to permit such movement only during the movement of the lever actuating leg 184 in the direction which closes the electrodes and when the force opposing the movement of the actuating leg exceeds a predetermined value so as to thus control the clamping pressure exerted by the electrodes on the workpiece. Dur ing such lost motion movement, the lever 176 moves independently of the pullrod 178 and of the

arms

94, 94 so that continued movement of the lever in the closing direction is ineffective to cause further closing movement of the arms. The presently preferred form of the connection between the pullrod and the depending leg of the lever is shown in FIGS. 2 and 11 and includes a coupling member or sleeve 196 which is slidably mounted on the right-hand end portion of the pullrod. The pullrod is threaded, as shown in FIG. 11, and receives a nut 198 and a second sleeve 200 which serve to provide a means for limiting the movement of the coupling member 196 in a direction toward the left-hand end of the pullrod. On the pullrod 178, there is also provided a spring means comprising a plurality of spring washers 202, 20-2 which act between the right-hand face of the coupling member 196 and a Washer 284 tourge the coupling member 196 into a normal position against the sleeve 260 and to oppose its movement to the right and away from the sleeve 200. The washer 2114 is maintained on the pullrod by another nut 206. By adjusting the nut 206 in one direction or another along the length of the pullrod, the initial biasing force exerted by the

washers

202, 202 against the coupling member may be varied so as to change the force on the coupling member necessary to move it to the right. Likewise, both the

nuts

198 and 206 may be moved in unison in one direction or another along the length of the pullrod to vary the normal position of the coupling member 196 with respect to the pullrod. The lower end of the depending lever leg 182 is bifuracted so as to straddle the coupling member 196 and is pivotally connected to the member 196 by two

pins

208, 208 each of which extends through an associated bifurcation and the Coupling member 196, as shown in FIG. 11. Each pin 208 is received in a slot formed in the corresponding bifurcation of the lever 182 and is held in the slot of a retaining piece 210 which is fastened to the bifurcation by

screws

212, 212.

The operation of the welding mechanism in moving between its opened and closed positions may be best understood by reference to the schematic diagram of FIG. 12. In this figure the solid lines represent the positions occupied by the various parts when the electrodes are in closed or clamping relationship with a workpiece, while the broken lines represent the positions occupied by the various parts when the electrodes are in an opened relationship. Assume that the parts are first in the closed position shown by the solid lines. To attain this position, the actuating leg 184 of the lever 176 is held in a raised position by the cam 88. The

arms

94, 94 are held in a position of minimum spacing between the electrodes by the engagement of the arms respectively with the

stops

112 and 114 or by the engagement of the electrodes with the workpiece. That is, in moving toward the closed position, the electrodes may engage and be arrested by the workpiece backed up by the mandrel before the arms engage the

stops

112 and 114. Generally, it is preferred thatthe stops 112 and 114 be so adjusted that the closing electrodes initially engage the workpiece and are then movable. a further distance toward each other as the workpiece is heated to produce the required upset, with the arms engaging the stops to limit their further movement at the point where the correct amount of upset is obtained. The presence of the mandrel, however, which backs .up part of the workpiece, may make it unnecessary to use the

stops

112 and 114 for this purpose. Also, the parts of the mechanism are generally adjusted so that when the lever actuating leg 184 is raised to close the electrodes, the electrodes engage the workpiece sometime before the leg reaches its fully raised position with the result that a sufiicient force opposing the movement of the lever is obtained to cause the depending leg 182 to compress the

spring washers

202, 202 and to move independently of the pullrod 178 and

arms

94, 94. This independent movement of the lever prevents the electrodes from crushing the workpiece, but the

spring washers

202, 202 nevertheless act on the pullrod so that when the lever moves with respect to the pullrod a substantially constant clamping effort is exerted by the electrodes on the workpiece so long as the arms are not both arrested by the

stops

112 and 114. I

To move the electrodes to an open or spread r613- tionship, the actuating leg 184 of the lever 176 is swung downwardly by the cam 88. During this movement, the lever pivots with respect to the associated arm 94 and with respect to the pullrod 178 with the result that the lower end of the leg 182 is moved some distance to the left while the upper end thereof moves some distance to the right. The movement of the lower end of the leg 182 is imparted to the pullrod and causes the left arm 94 to be pivoted in the counterclockwise direction to bring its electrode away from the mandrel and workpiece. The movement of the upper end of the leg 182 is directly imparted to the right arm 94 and causes it to move in the clockwise sense to bring its electrode away from the mandrel and workpiece. Once the actuating leg 184 is started in its downward movement, the

arms

94, 94 may move independently of each other and are in a somewhat floating condition with respect to the limits of movement established by the

stops

110, 112, 114 and 116. That is, the two arms do not necessarily move simultaneously to their closed position, but, as is generally the case, one arm may move until it engages the workpiece or the associated

stop

110 or 116 and then the linkage will operate to move the other arm. The cam 88 is, of course, so arranged on the cam shaft 68 and provided with a cam groove of such shape so that the

arms

94, 94 are spread for receiving a workpiece between the electrodes during the time the stripper rods are actuated to deliver the workpiece to the forward mandrel portion and so that the

arms

94, 94 are thereafter closed to bring the electrodes into clamping and welding relationship with the workpiece and to hold them in such relationship while the machine executes its next feeding and forming phases.

Having thus described the structure of thewelding mechanism 92, its operation in conjunction with the operation of the wire or strip forming machine 20 may now be briefly summarized as follows. At the start of each operating cycle of the machine 20, the

arms

94, 94 of the welding mechanism are spread apart so as to receive therebetween a formed workpiece which is moved from the rear to the forward mandrel portion by the

stripper rods

132, 132. The first phase of the operation of the machine 20, which is the feeding phase, is then begun and during this phase the feeding mechanism 32 is operated to move the strip 34 transversely of the mandrel 30, or to the right as viewed in FIG. 1, and to bring the right-hand end portion of the strip into working relationship with the mandrel 30. The cutoff mechanism 38 is then operated to cut a portion of the strip from the right-hand end thereof, which portion becomes the workpiece. At the same time as the cutoff mechanism is operated, or shortly before, the stock clamp 40 is lowered to hold the cut workpiece against the mandrel 30. The machine 20 then begins its forming phase, during which phase the

slides

22, 24, 26, and 28 are operated in a predetermined sequence to bend the workpiece around the mandrel and into the desired shape while the workpiece remains at the same position on the rear mandrel portion.

As the machine 20 executes its feeding and forming phases, the welding mechanism 92 is operated by the cam 88 to close the

electrodes

96, 96 against the previously formed workpiece, and after the electrodes are so closed on the workpiece, the transformer 174 is operated by the associated electronic control system to supply current at the proper voltage and amperage to the

electrodes

96, 96 through the

flexible bus bars

158 and 166. The current passes between the electrodes and through the workpiece until the material adjacent the opposed ends 128, 128 of the workpiece are heated to the fusion temperature. Once the ends of the workpiece are heated to this temperature, the metal thereof flows together to produce the weld, and a slight amount of upsetting is produced by the clamping pressure exerted against the workpiece by the electrodes. After this fusion takes place, the welding current is removed and the electrodes are held in clamping relationship with the workpiece until the latter is sufliciently cooled to permit the pressure to be relieved without danger of rupturing or stretching the weld by the natural tendency of the workpiece to return to its original shape. The welding steps of clamping the workpiece, heating the same, upsetting and cooling, are of such duration as to consume the time allotted to the feeding and forming phases of the machine 20 so that when the

arms

94, 94 of the welding mechanism are spread at the end of the cooling period, the forming phase of the machine 20 is also completed so that another formed workpiece is located on the rear mandrel portion. The

stripper rods

132, 132 are then actuated to move the newly formed workpiece to the forward mandrel portion for welding, and in so doing, the newly formed workpiece pushes the welded workpiece from the mandrel and onto the guide wire 134 from whence it is conducted to a suitable receptacle. The

stripper rods

132, 132 are then retracted and the welding mechanism 92 and the forming machine 20 are started on a repeat performance.

The invention claimed is:

l. The combination in a wire or strip forming machine of, a mandrel having a first portion at which a workpiece is formed by being bent around the mandrel and a second portion at which the workpiece is Welded, means for moving a workpiece from said first to said second mandrel portion after it is formed at said first portion, two generally parallel upright arms pivotally supported at their lower ends for swinging movement of the arms toward and away from each other in a common plane normal to the axis of said mandrel, welding electrodes connected to the upper end portions of said arms in opposing relation to each other and having working faces conforming to at least a portion of the workpiece to be welded, the said two arms being so arranged that said welding electrodes are disposed on opposite sides of said second mandrel portion and are movable into and out of clamping engagement with a workpiece positioned on said second mandrel portion, stop means associated with each arm for limiting its swinging movement in a direction away from said mandrel, a lever pivotally connected to the upper end portion of one of said arms and which member includes a downwardly extending leg and an actuating leg, and a pullrod having one end pivotally connected to the other of said arms and having its other end pivotally connected to said downwardly extending lever leg so that swinging movement of said lever actuating leg in one direction causes said arms to be moved toward one another for clamping a workpiece between said welding electrodes while movement of said lever actuating leg in the other direction causes said arms to be moved away from each other to spread apart said electrodes for receiving or discharging a workpiece.

2. The combination as defined in claim 1 further characterized by a cam for operating said lever actuating leg which cam is driven in timed relationship with said means for moving a workpiece from said first to said second mandrel portion, the said cam serving to operate said lever actuating leg to spread apart said arms as a workpiece is moved to said second mandrel portion and to thereafter move said arms toward one another to clamp the workpiece between said electrodes.

3. A welding mechanism for welding together the adjacent ends of a workpiece which mechanism comprises, two generally parallel upright arms pivotally supported at their lower ends for swinging movement of the arms toward and away from each other in a common plane, welding electrodes connected to the upper end portions of said arms in opposing relation to each other and having working faces conforming to at least a portion of the workpiece to be welded, a lever pivotally connected to the upper end portion of one of said arms and which lever includes a downwardly extending leg and an actuating leg, a pullrod having one end pivotally connected to the other of said arms and its other end pivotally connected to said downwardly extending lever leg so that swinging movement of said lever actuating leg in one direction causes said arms to be moved together for clamping a workpiece between said welding electrodes while movement of said lever actuating leg in the other direction causes said arms to be moved away from each other to spread apart said electrodes for receiving or discharging a workpiece, and means engageable with each of said arms for limiting their movement toward each other to provide for a predetermined minimum spacing between said electrodes to control the amount of upsetting which occurs as the workpiece is welded.

4. The combination in a cyclically operable wire or strip forming machine of, a bed, a mandrel connected with said bed and projecting outwardly therefrom so as to have a rear portion located adjacent said bed and a forward portion located some distance away from said bed, means for feeding a workpiece transversely of said mandrel to said rear portion thereof, a plurality of forming tools which are movable relative to said bed and which sequentially cooperate with said rear mandrel portion throughout a predetermined forming phase of each cycle of operation of the machine to progressively bend the workpiece around the said mandrel and into such a shape as to bring its two ends into juxtaposed abutting relationship after it is delivered to said rear mandrel portion by said feeding means and while it remains at the same axial position on said rear mandrel portion, means for moving a workpiece from the rear to the forward portion of said mandrel after the completion of said forming phase, and means for Welding together the juxtaposed ends of a workpiece at the forward portion of said mandrel while another workpiece is bent around the rear portion of said mandrel by said tools.

5. A welding mechanism for welding together the adjacent ends of a workpiece which mechanism comprises, two generally parallel upright arms pivotally supported at their lower ends for swinging movement of the arms toward and away from each other in a common plane, stop means associated with each arm for limiting its swinging movement to a given angular range between two end positions, welding electrodes connected to the upper end portions of said arms in opposing relation to each other and having working faces conforming to at least a portion of the workpiece to be welded, a lever pivotally connected to the upper end portion of one of said arms and which lever includes a downwardly extending leg and an actuating leg, and a pullrod having one end pivotally connected to the other of said arms and having its other end pivotally connected to said downwardly extending lever leg so that swinging movement of said lever actuating leg in one direction causes said arms to be moved together for clamping a workpiece between said welding electrodes while movement of said lever actuating leg in the other direction causes said arms to be moved away from each other to spread apart said electrodes for receiving or discharging a workpiece.

6. A welding mechanism for welding together the adjacent ends of a workpiece which mechanism comprises, two generally parallel upright arms pivotally supported at their lower ends for swinging movement of the arms toward and away from each other in a common plane, stop means associated with each arm for limiting its swinging movement to a given angular range between two end positions, welding electrodes connected to the upper end portions of said arms in opposing relation to each other and having working faces conforming to at least a portion of the workpiece to be welded, a lever pivotally connected to the upper end portion of one of said arms and which lever includes a downwardly extending leg and an actuating leg, at pullrod having one end pivotally connected to the other of said arms, means for connecting the other end of said pullrod to said downwardly extending lever leg and which means serves to permit both a pivotal and a lost motion movement of said downwardly extending leg relative to said pullrod so that swinging movement of said lever actuating leg in one direction causes said arms to be moved together for clamping a workpiece between said welding electrodes while movement of said lever actuating leg in the other direction causes said arms to be moved away from each other to spread apart said electrodes for receiving or discharging a workpiece, and biasing means which serves to oppose said lost motion movement of said downwardly extending lever leg relative to said pullrod and which permits such movement only after the clamping pressure exerted by said electrodes on a workpiece exceeds a predetermined value.

7. A welding mechanism for welding together the adjacent ends of a workpiece which mechanism comprises, two general-1y parallel upright arms having welding electrodes connected to their upper end portions in opposing relation to each other and which electrodes have working faces conforming to at least a portion of the workpiece to be welded, means pivotally supporting said arms at their lower ends for relative swinging movement of said arms between a spread workpiece receiving relationship and a closed workpiece clamping relationship, a lever pivotally connected to the upper end portion of one of said arms and which lever includes a downwardly extending leg and an actuating leg, a pullrod having a first end thereof pivotally connected to the other of said arms, a coupling element mounted on the other end of said pullrod for relative sliding movement longitudinally thereof, a stop for limiting the sliding movement of said coupling element in a direction toward said first end of said pullrod to a predetermined normal position, biasing means for urging said coupling member into said normal position and for opposing its movement therefrom in a direction away from said first end of said pullrod, and means pivotally connecting said depending lever leg tosaid coupling element with the result that said pullrod and said lever cooperate with said two arms so as to move the same toward a spread relationship as the actuating leg of the lever is swung in one direction and toward a closed re lationship as the actuating leg of the lever is swung in the other direction and with the further result that said biasing means permits said coupling element to move relative to said pullrod so that said lever may move independently of said arms when the force opposing the movement of said lever actuating leg exceeds a predetermined value during its movement in the direction which closes said arms.

8. A welding mechanism as defined in claim 7 further characterized by means for adjusting the position of said stop on said pullrod so as to vary the normal position of said coupling member on said pullrod.

9. A welding mechanism as defined in claim 7 further characterized by means for adjusting the initial biasing force exerted by said biasing means on said coupling member so as to vary the amount of force necessary to be exerted on said actuating leg before said lever moves independently of said arms.

10. The combination in a wire or strip forming machine of, a mandrel having a rear portion and a forward portion, means for feeding a workpiece transversely of said mandrel to said rear portion thereof, a first pair of forming tools located on opposite sides of said rear mandrel portion and movable radially thereof toward and away from said mandrel to at least partially form said workpiece about said rear mandrel portion, a second pair of forming tools located on opposite sides of said rear mandrel portion and movable radially thereof toward and away from said mandrel to further form said workpiece about said rear mandrel port-ion, means for moving a formed workpiece from said rear to said forward mandrel portion, and a pair of Welding electrodes located on opposite sides of said forward mandrel portion and movable generally radially thereof toward and away from said mandrel to weld a formed workpiece positioned on said forward mandrel portion.

11. The combination in a wire or strip forming machine of, a machine bed, a mandrel fixed to said machine bed and projecting horizontally outwardly therefrom, the outwardly projecting part of said mandrel including a rear portion located adjacent said bed and a forward portion located outwardly beyond said rear portion, means for feeding a workpiece transversely of said mandrel to said rear portion thereof, a first pair of forming tools located respectively above and below said rear mandrel portion and movable vertically toward and away from said mandrel to at least partially form said workpiece about said rear mandrel portion, a second pair of forming tools located respectively on either side of said rear mandrel portion and movable horizontally toward and away from said mandrel to further form said workpiece about said rear mandrel portion, means for moving a formed workpiece from said rear to said forward mandrel portion, and a pair of welding electrodes located on opposite sides of said forward mandrel portion and movable generally radially thereof in unison toward and away from said mandrel to weld a formed workpiece positioned on said forward mandrel portion.

12. The combination defined in claim 11 further characterized by means for moving said forming tools sequentially in accordance with a given cycle of operation throughout which cycle a workpiece is completely formed at said rear mandrel portion, and means for moving said electrodes in timed relationship with said forming tools and in such a manner that said welding electrodes are in 15 welding relationship with a workpiece on said forward mandrel portion throughout the major portion of said cycle.

13. The combination defined in claim 11 further characterized by said means for moving a formed workpiece including at least one ejector rod positioned parallel to said mandrel and reciprocable axially thereof, said ejector rod having a forward face normally located rearwardly of a workpiece on said rear mandrel portion and which forward face is engageable with such a workpiece to move the same forwardly on said mandrel, said ejector rod further having such a stroke that at the end of the forward movement of said ejector rod said workpiece is properly positioned on said forward mandrel portion for cooperation with said welding electrodes.

14. A cyclically operable machine for producing a plurality of formed and welded articles from an indefinite length of wire or strip material, said machine comprising in combination a bed, a mandrel connected with said bed and projecting outwardly therefrom so as to have a rear portion located adjacent said bed and a forward portion located some distance away from said bed, means for feeding the forward end portion of said indefinite length of material transversely of said mandrel to said rear mandrel portion, means for cutting said forward portion of said indefinite length of material from the remainder thereof to provide a workpiece, means adjacent said rear mandrel portion for forming said workpiece around said rear mandrel portion and into such a shape as to bring its two ends into juxtaposed abutting relationship, means for moving said workpiece from the rear to the forward portion of said mandrel after being formed at said rear portion, and means for welding together the juxtaposed ends of said workpiece at the forward portion of said mandrel.

References Cited in the file of this patent UNITED STATES PATENTS 1,663,970 Brenzinger Mar. 27, 1928 2,236,848 Graham et al. Apr. 1, 1941 2,259,914 Weisenburg Oct. 21, 1941 2,307,089 Winters Ian. 5, 1943 2,472,849 Paynter June 14, 1949 2,484,868 Winters Oct. 18, 1949 2,915,616 Griflin Dec. 1, 1959