US2931892A - Electrical heating apparatus - Google Patents

Description

April 1960 w. STICH ETAL 2,931,892

ELECTRICAL HEATING APPARATUS Filed April 2, 1958 6 Sheets-Sheet 1 April 5., 1960 w. STICH ET AL 9 ELECTRICAL HEATING APPARATUS Filed April 2, 1958 6 SheetsSheet 2 April 5, 19'60 w. STlCH ETAL 2,931,892

ELECTRICAL HEATING APPARATUS Filed April 2, 1958 r 6 Sheets-Sheet 3 MAME April 5, 1960 w. STICH ET AL ELECTRICAL HEATING APPARATUS 6 Sheets-Sheet 4 lm eman' WM 0% f mm! s. M M

' Filed April 2, 1958 April 5, 196b w. STICH ETAL 2,931,892

ELECTRICAL HEATING APPARATUS Filed April 2, 1958 6 Sheets-Sheet 5 Jaye/Iran Wk 8% TIT/M211 S.

April 5, 1960 w. STICH ET AL 2,931,892

ELECTRICAL HEATING APPARATUS Filed April 2, 1958 6 Sheets-Sheet 6 150 ji 3 I62 15/ PI FL w Inventor: mm 9% mm sch/h WWW United States atent O ELECTRICAL HEATING APPARATUS Wilhelm Stich, Wattenscheid-Hontrop, and Hans Huethe, Dusseldorf, Germany, assignors to Bocltumer Verein fuer Gusstahlfabrikation Aktiengesellschaft, Boehum, Germany Application April 2, 1958, Serial No. 725,909

laims priority, appiication Japan August 28, 1957 15 Claims. (Cl. 219-156) The present invention relates to electrical heating apparatus.

More particularly, the present invention relates to an apparatus for heating a workpiece which is electrically conductive by conducting electricity through the workpiece so that the resistance of the workpiece itself causes it to become heated. For example, the structure of the present invention may be used in rolling mill installations where elongated steel billets are to be heated up to a temperature of from 1000 to 1200 C. before being rolled.

When a billet of this type is heated as by pressing a pair of electrodes against the ends of the billet, there is a danger of bending of the billet particularly where the billet is of a relatively long slender construction. Moreover, some of the material of the workpiece such as the billet may become burned away during engagement with electrodes so that the desired pressure between the electrodes and the workpieces is not maintained.

One of the objects of the present invention is to overcome the above drawbacks by providing in a heating apparatus of the above type a means which is capable of maintaining the workpiece under tension while it is being heated and while it is engaged by the electrodes, so that there is absolutely no danger of the bending of the workpiece even if it is of relatively long slender configuration.

Another object of the present invention is to provide a means for maintaining the electrodes in operative engagement with the workpiece even if part of the material of the workpiece should burn away, and moreover the tension in the workpiece, referred to above, is also maintained.

A further object of the present invention is to provide a structure which is capable of uniformly heating an elongated workpiece over its entire length.

It is also an object of the present invention to provide a structure which is capable of uniformly heating an elongated workpiece over its entire length.

It is also an object of the present invention to provide a structure capable of accomplishing all of the above objects and at the same time composed of simple and relatively constructed elements which are very reliable in operation.

With the above objects in view, the present invention includes in an electrical heating apparatus a pair of electrodes which are spaced from each other along a predetermined axis and which are adapted to engage an electrically conductive workpiece located between the electrodes in order to establish an electrical connection therewith so that a current may flow through the workpiece in order to heat the same. These electrodes are respectively carried by a pair of support means which support the electrodes for movement back and forth along this axis. A pair of gripping means are located adjacent the electrodes for gripping the workpiece at portions thereof respectively located adjacent the electrodes, and the pair of gripping means are connected to the 2,931,892 a Patented Apr. '5, 1960 "ice electrodes for movement therewith along this axis, so that when the electrodes are in engagement with the workpiece which is simultaneously gripped by the pair of gripping means and then the electrodes are urged apart from each other, the workpiece will be maintained under tension so that there is no danger of bending of the workpiece.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is a schematic side elevational view, partly in section, of one possible heating apparatus according to the present invention; 1

Fig. 2 is a fragmentary side elevational view, partly in section, on an enlarged scale as compared to Fig. l, of an electrode and gripping means assembly which forms a unit of the present invention, the structure being shown in Fig. 2 turned through with respect to its illustration in Fig. l; l

Fig. 3 is a transverse sectional elevational view taken along line IIl--IIl in the direction of the arrows of Fig. 2;

Fig. 4 is a fragmentary schematic partly sectional side elevational view of another embodiment of an electrical heating apparatus according to the present invention;

Fig. 5 is a sectional elevational view on an enlarged scale showing one of the electrodes and gripping means units of Fig. 4 as well as the structure for operating this unit;

Fig. 6 is a transverse sectional view of an electrically conductive sleeve means which is adapted to grip a part of the structure of Fig. 4 for establishing part of the electrical circuit, Fig. 6 also showing the structure for moving the sleeve means to and from its operating position; r

Fig.- 7 is a fragmentary transverse elevational view showing another embodiment of a structure for moving the sections of the sleeve means of Fig. 6 to and from an operating position;

Fig. 8 is a sectional plan view taken along line VIII-VIII of Fig. 7 in direction of the arrows;

Fig. 9 is a fragmentary sectional side elevational view on an enlarged scale showing the details of an electrode supporting structure according to the present invention; and

' Fig. 10 shows another embodiment of part of the electrode carrying structure of Fig. 9.

Referring now to Fig. 1 the elongated electrically conductive workpiece 1, which may, for example, be in the form of an elongated billet which has to be pre-heated before it is rolled, rests on a plurality of rollers 2 which are supported for rotation by a plurality of pins 3 which are respectively carried by standards 4 which in turn are supported on portions 5 of the base of the machine. This workpiece 1 may be lowered into the position shown in Fig. l by a suitable crane, for example, and although in the diagrammatic illustration of Fig. 1 it may appear that part of the structure prevents up and down movement of the workpiece 1, it is pointed out that in the actual construction the parts are so arranged that the workpiece 1 can be moved without interference to and from the position shown in Fig. 1, certain parts of the structure being illustrated in Fig. 1 in positions over the workpiece solely for the purpose of illustrating all of the structure of the invention in the clearest possible manner. The rollers 2 have a configuration which conforms to the cross sectional configuration of the exterior surface of the workpiece 1, and this workpiece 1 is capable of being shifted back and forth to the right and left, as viewed in Fig. l, on the rollers 2.

The opposite end faces of the workpiece 1 are respectively engaged by a pair of electrodes 7, and a pair of gripping means 8 are respectively located adjacent the electrodes '7 for gripping the workpiece at portions thereof adjacent to the electrodes, respectively. The left electrodes 7 and gripping means 8 of Fig. 1 form a unit 9, while the right electrode 7 and gripping means 8 of Fig. 1 form a unit 19. The details of the unit 9 are shown on an enlarged scale, as compared to Fig. 1, in Figs. 2 and 3, and it is to be understood that unit 10 is constructed in the same way with the exceptions noted below.

Referring now to Figs. 2 and 3, it will be seen that the housing 11 of the unit 9, which is illustrated only schematically in Fig. 1 as a smooth body, is actually in the form of a special casting which is fixed to the flange 12 of the shaft 13 by any suitable screw members or the like. These screws are not illustrated in the drawings. The housing 11, as shown in Fig. 1, has a pair of bottom extensions 14 carrying rollers which ride on a track 15, so that in this way the housing 11 and all of the structure carried thereby is supported for movement to the right and left, as viewed in Fig. 1. The portion of the housing 11 which is located opposite and distant from the flange 12 is constructed as an electrode carrier 16, this portion 16 of the housing being hollow and having a right open end, as viewed in Fig. 2, which is filled by the electrode 7 which extends into this right open end of the hollow part 16 in order to close the interior thereof. For example, the electrode '7 may be threaded into an opening at the right face of the portion 16 of the housing 11 in order to close this opening.

A portion of the electrode 7 which is directed toward the interior of the hollow portion 16 is engaged by cooling water or the like which is located in this hollow space. The hollow space is not illustrated in Fig. 2, since this feature is described in greater detail in connection with Figs. 9 and 10 below.

A pair of pins 17 are fixed to and extend to the right from the portion 16 of the electrode carrier, and these pins serve to connect to the unit a pair of curved water tubes 18 and 19 which are formed with openings which provide spray nozzles through which the cooling water is sprayed onto the electrode. The nozzles of the tube 18, in particular direct the spray liquid onto the electrode '7, while the nozzles of the tube 19 direct the spray liquid at an angle of 50, for example, to the axis of the workpiece, toward the electrode so that this liquid may engage the workpiece itself in order to cool the end which is engaged by the electrode.

The housing 11 carries equidistantly from and parallel t0 the common axis of the workpiece 1 and the electrode 7, a pair of hollow sleeves 2% each or" which is provided at its right end, as viewed in Fig, 2, with a flange 21 and at its left end with an end wall 22, and these slee es 29 are insulated with respect to the remainder of the housing by a pair of sleeves of electrically non-conductive material which are indicated in Fig. 2 by the heavy line located at the upper and lower part of the lower sleeve shown in Fig. 2. In each of the sleeves 20 there is located a second sleeve 23 which is telescopically slidable in the sleeve 20, and this sleeve 23 has threaded or Welded onto the same a circular flange 24. The portions of the sleeves 23 which extend to the right beyond the flanges 24 extend into openings of a carrier ring 25 which is provided with a plurality of cars 27 extending forwardly from the right face of the carrier ring 25 and serving to support four sets of levers 28, 29, two of these sets being clearly visible in Fig. 2. Each lever 29 is in the form of a simple link pivotally connected at its left end, as viewed in Fig. 2, to one of the members 2'7 and its right end to a gripping member, Fig. 2 75 showing the pair of gripping members 42 which are movable toward and away from the workpiece 1 so as to grip the same. The members 28, on the other hand, are in the form of hell cranks one arm of Which is parallel to the arm 29 and the longer arm of which extends substantially radialiy toward the axis of the workpiece, as indicated in Fig. 2. Thus, two pairs of such linkages are provided on opposite sides of the workpiece, and the longer arms of each bell crank 28 at each side of the unit are pivotally connected with a pair of links 31 which in turn are pivotally connected through a pivot pin 22 with the portion 33 of an elongated piston rod 34 which extends into a pneumatic cylinder 35 fixedly carried by the housing H. in an eye 38 thereof. Fig. 3 clearly illustrates the arrangement of the pair of eyes 38 at the opposite sides of the axis of the shaft 13, and Fig. 3 furthermore shows the pair of pneumatic cylinders 35 mounted in these eyes. It should be noted, as is evidenced from Fig. l which shows the pair of pneumatic cylinders 35 above and below the shaft 13, that the structure of Figs. 2 and 3 is turned through 90 with respect to the illustration thereof in Fig. l, solely for the sake of clarity. The pneumatic cylinder 35 is provided with a connection 36 through which compressed air is adapted to be introduced on one side of the piston within the cylinder, while it also has a second connection 37 through which air is adapted to be introduced on the opposite side of the piston, so that depending upon the direction in which the air is introduced the piston rod 34 will be shifted in one direction or the other. When the piston rod is shifted toward the left, as viewed in Fig, 2, the cranks 28 will be turned in a direction which will cause the gripping members 42 to approch each other and grip the workpiece 1, the links 29 cooperating with the shorter arms of the bell cranks 28 to form a parallelogram linkage which maintains the gripping members vertical while at the same time moving the same toward and away from the workpiece. When the piston rod 34 is advanced to the right, as viewed in Fig. 2, by introduction of air into the cylinder 35 through the connection 37, the gripping members 42 are moved away from the workpiece in order to release the same.

Each of the pneumatic cylinders 35 terminates at its left end, as viewed in Fig. 2, in a central pin portion 39 through which an elongated pin 49 extends vertically, and each pin 40 is connected with the ends of a pair of elongated straps $1. The arrangement of these straps is clearly shown in Fig. 3 from where it is seen that the straps extend across the shaft 13 while being connected to the pins 39 of both of the pneumatic cylinders 35. Furthermore, as is shown in Fig. 2, the straps 41 bear against the left surface of the flange 12 of the shaft 13, as viewed in Fig. 2. The straps 41 are fixed with the Flange 12 as by being screwed thereto, these screws not being illustrated in the drawings.

Within each pair of telescoping sleeves 2G and 23 is arranged an elongated coil spring 26 the left end of which bears against the end wall 2-2 of each sleeve 2 and the right end of which bears against the carrier ring 25. Thus, with this arrangement the carrier ring together with the gripping means carried thereby is sup ported for yieldable movement to the left, as viewed in Fig. 2, with respect to the housing 11 and the electrodes 7 carried thereby, so that assuming that the workpiece ii is capable of being moved to the left, as viewed in Fig. 2. and that a part of the mate-rial on the end face of the workpiece 1 burns away therefrom due to the electrical connection with the electrodes 7, then the pneumatic pressure within the cylinder 35 which urges the piston to the left, as viewed in Fig. 2, is capable of moving the entire carrier ring 25 together with all the gripping structure to the left, as viewed in Fig. 2, against the force of the springs 26, so as to maintain the workpiece 1 in engagement with the electrode even though part of the material has been burned away.

The pivot pin 32 is surrounded by a sleeve of electrically non-conductive material so that this pivot pin 32 is insulated electrically from the remainder of the structure, and in the same way the links 31 have no contact with the portion 33 which may be bifurcated to receive the left ends of the links 31, as viewed in Fig. 2, between the bifurcations of the portion 33. Thus, there can be no transfer of the electrical current back to the piston rod 34. The edges of the gripping members 42 which engage the workpiece 1 have a configuration which conforms to the configuration of the exterior surface of the workpiece 1.

The housing 11 carries above and below the sleeves 20 and in parallel relation thereto a pair of additional sleeve means which are adapted to be placed into electrical communication with a pair of electrically conductive members 64 which form part of the electrical circuit to the electrodes. Each of these sleeve means includes a sleeve half 44 pivotally fixed with the housing 11 and a second sleeve half 46 pivotally connected with the sleeve half 44 by a pivot pin 45. The turnable sleeve halves 46 are each provided with a free end 47 carrying a plate 48 which is adapted to be engaged by a lever 53 for turning the sleeve sections 46 respectively towards the sleeve sections 44 so that the pair of sleeve means tightly grip the pair of electrically conductive bars 64. The housing 11 is formed with a pair of bores which respectively slidably receive a pair of tubes 49 having dome-shaped outer ends engaging the free ends 47 of the sections 46, and within each of these tubes 49 is arranged a spring 50 urging the tube outwardly of the housing 11, so that the springs 50 together with the sleeves 49 urged the sleeve sections 46 respectively away from the sleeve sections 44 to a position out of engagement with the conductors 64, respectively. Each of the arms 47 is provided with a plate 48 which is engaged by the lever 53, and the levers 53 are respectively supported for turning movement by a pair of pins 52. e

In order to actuate the levers 53 for moving the sleeve sections 46 respectively toward the sleeve sections 44, the outer free ends of the levers 53 are pivotally connected through a pivot pin 55 and a member 56 pivotally supported from the pivot pin 55 to a piston rod 57 connected with a piston in a pneumatic cylinder 58 which has an extension 59 pivotally supported on a bracket 61 carried by the housing 11. A pair of conduits 62 and 63 respectively communicate with the opposite ends of the pneumatic cylinder 58 for directing the compressed air into thetop end of the cylinder 58 so as to urge the levers 53 in a direction which causes the sleeve sections 46 to be moved respectively toward the sleeve sections 44, or the compressed air may be introduced through conduit 62 for urging the piston rods 57 in a direction which causes the levers 53 to turn in a direction which frees the sleeve sections 46 to the springs 58 to be moved thereby away from the sleeve sections 44, respectively, so as to be placed out of gripping engagement with the conductors 64. Each of the sleeve means formed by the pair of pivotally connected sections 44 and 46 forms a means for electrically connecting the electrode 7 with the source of current, and as is clearly shown in Fig. 2, the inner surfaces of the sleeve sections 44 and 46 which engage the exterior surface of the conductor bar 64 are formed with grooves 65, so that any lubricant on the bar 64 will be pressed into these grooves while the relatively small areas of the inner surfaces of the sections 44 and 46 located between the grooves will penetrate through the lubricant into metal to metal contact with the bar 64 so as to provide an additional electrical connection with this bar.

It should be noted that only the unit 9 is provided with a pair of sleeve means for engaging the electrically conductive bars 64. The unit is identical with the unit 9 except that it. is not provided with any sleeve means for establishing an electrical connection with the pair of con ductors 64.

Referring now to the upper left portion of Fig. 1, it will be seen that the left free end portion of the shaft 13 is formed as a cylinder 66 which receives a stationary piston 69 which is fixed at 71 to a bracket 72 which is carried by the rear wall 73 of a carriage 74 which is movable to the right and left, as viewed in Fig. 1, through engagement of the rollers 79 of the carriage with the track 80. The piston 69 is stationary in the sense that it is stationary with respect to the carriage 74 while moving with the latter. A pinion 83 is turnably carried by the carriage 74 and is driven through any suitable worm and wormwheel drive which provides an irreversible drive, so that the pinion 83 will remain in whatever angular position it happens to be in when the drive through the pinion 83 is stopped. Of course, the pinion 83 can be turned in one direction or the other, and this pinion cooperates with an elongated rack 81 which may be located beside the carriage 74 or which may extend through suitable openings thereof, this rack 81 being carried by suitable standards 82 fixedly carried and turned by the base of the machine. Thus, the pinion 83 may be driven so as to locate the carriage 74 in a position to enable the apparatus to handle certain types of elongated workpieceswhich are within a particular range of length, and the carriage 74 need not be moved to handle all of the work ieces within this predetermined range of length.

The shaft 13 is guided for movement with respect to the carriage 74 through the medium of a pair of rollers 77 which engage upper and lower surfaces of the shaft 13 and which are turnably supported by pins 78 fixedly carried by the carriage 74.

The cylinder 66 which is formed by the left free end portion of the shaft 13 and which receives the piston 69 is limited at its right end, as viewed in Fig. 1, by a partition 68 located in the shaft 13, and its left end by a cylinder end wall 67 which may be threaded onto the left end of the shaft 13, as viewed in Fig. 1, and through which the piston rod 70 extends, a suitable sealing gland, such as a stufiing box or the like is provided on the end wall 67 around the piston'rod 70 so as to provide a fluid-tight connection while at the same time permitting the cylinder to slide with respect to the piston rod 71.

A pair of compressed air conduits and 76 respectively communicate with the interior portions of the cylinder 66 which are located on opposite sides of the piston 69, and these conduits 75 and 76 extend from a valve 101 which controls the flow of compressed air from a conduit 102 to one or the other of the conduits 75 or 76, this conduit 102 communicating with a compressed air tank 103.

In the arrangement shown in Fig. 1, instead of circular cooling water tubes 18 and 19 as shown in Fig. 2, the structure includes a pair of cooling water discharge nozzles 84 provided to spray cooling water in the manner indicated in Fig. l at each of the electrodes and the end of the workpiece in engagement therewith, and these nozzles 84 communicate with a cooling water supply conduit 35 which in turn communicates with a valve 174 which is electrically controlled so as to supply cooling Water from a cooling Water source 175 through the valve 174 and the conduits to the nozzles 84, this valve 174 being electrically actuated in a manner described below.

The unit 10 shown at the upper right portion of Fig. 1 includes an elongated hollow conductor 86 which extends completely through the unit 10 and terminates at its left end in the electrode carrier 87, so that the structure of the unit It) differs from the structure of the unit 9 in this manner also. The elongated electrically con ductive member 86 is formed at its right end, as viewed in Fig. 1, as a hollow cylinder 88 which receives a stationary. piston fixed at its right end, as viewed in Fig. 1, to a bracket 72' which is carried by a stationary base '7 part 93 of the machine which supports the member 89 which directly carries the bracket 72.

The elongated conductor 86 which is connected with and carries the right electrode 7 of Fig. 1 has a downwardly directed extension 90 electrically connected with two groups of elongated copper laminations 91 which are electrically connected at their bottom ends with an electrically conductive member 92 which is insulated from the base of the machine. This conductor 2 serves to electrically connect the laminations 91 with the end 96 of the secondary coil of the transformer 17%). The other end 94 of the secondary coil of the transformer is electrically connected with an electrically conductive member 95 which is also electrically insulated from the base of the machine, and this electrically conductive member 95 is in electrical engagement with and contributes to the support of the pair of electrically conductive bars 64 which extend upwardly from the conductor 95 and which at the elevation of the axis of the workpiece extend to the left horizontally while remaining parallel to this axis and spaced at opposite sides thereof. The con ductors 64, only one of which is shown in Fig. l, have free end portions 97 which are located in the position shown in Fig. 1, so that irrespective of the length of the workpiece and the position of the carriage 74 the pair of sleeve means of the unit 9 will always be able to be placed in electrical engagement with the pair of conductors 64 which remain stationary at all times.

Of course, in some installations it may be possible to eliminate the flexible conductors 91 which permit the unit it} together with the housing 86 to shift axially while maintaining the electrical connection to these parts, and instead a pair of additional conductor bars may be stationarily fixed with the conductor 92 and may extend to the region of the unit which in this case will include a pair of sleeve means similar to those shown in Fig. 2 for being placed in electrical engagement with such a pair of stationary conductors.

When the workpiece l is lowered as by a suitable crane or the like onto the supporting rollers 2, the parts at this time being shifted away from each other so as to provide suificient space for the workpiece 1 so that when the parts approach each other the pair of gripping means 8 will be able to move over the ends of the workpiece and the pair of electrodes 7 will be able to move into engagement with these ends, the workpiece 1 engages a plunger 9h of an electrical switch which is urged upwardly by a suitable spring, as shown in Fig. 1, so that when the workpiece 1 is not in the position on the machine the switch 99 is open. This switch is carried by a bracket @3 which is supported by the base of the machine. Thus, whenever a workpiece is placed on the rollers 2, the switch 99 will close, and in this way a relay will be energized, as is apparent from Fig. 1. This relay includes the normally closed switch lt ilb and the normally open switch 169a. Therefore, as soon as the workpiece 1 is lowered into the position shown in Fig. 1, the relay 1% is energized so as to close the switch liilla and open the switch 10%, and as a result the valve till has its solenoid actuated so as to place the conduit 19?: in communication with the conduit 7 so that the compressed air enters into the cylinder 66 to the right of the piston 69 for advancing the shaft 13 to the right, as viewed in Fig. 1. Air which returns to the valve is expelled to the outer atmosphere through the outlet 17o the conduit 76 has a branch extending to the cylinder 88 to the interior portion thereof located to the left of the stationary piston therein, so that the conductor together with the unit 16 shifts to the left, while the shaft 13 together with the unit 9 shifts to the that at this time the pair of gripping means are me ed over the ends of the workpiece and the electrodes 7 are moved respectively into engagement with the end faces 6 thereof. Wherever required, such as at the connections with the cylinders 66 and 83, the fluid conduits are flexible, although they. may not be shown in the drawing this way.

Once the electrodes 7 have in this way been placed respectively in engagement with the end faces 6 of the workpiece, the pressure within the cylinders 66 and 88 builds up so as to cause the valve device 164 to close a switch which will energize a relay which includes the normally open switch 165e, the normally open switch 165b, the normally closed switch lilSc, the normally closed switch 105 and the normally open switches 105d and N52. Therefore, depending upon the setting of the device 104 which responds to the pressure in the cylinders at this time, the relay 105 will be energized when the electrodes press with a predetermined force against the ends of the workpiece, and as a result the energizing of the relay will cause the switches 105e, 1050., 105b, and 105a to close, while the switches 1050 and 105] will open. The opening of the switch N5 of course deenergizes the relay 100 so that the switch lllila again opens while the switch lllilb closes, and this reverses the position of the valve 101. The closing of the switch IltlSa causes the transformer to become energized through a suitable delay relay. The closing of the switch 195d results in opening of the valve 174 so that the cooling water now flows to the nozzles 84 or in the case of Pig. 2 to the pipes 18 and 19. The switch 195:: serves as a switch for holding the relay 105 energized even after the switch Hi4 opens. The opening of the switch ltlSc and the closing of the switch 195!) causes the valve 173 to act so as to place the compressed air in the conduit 171 which communicates with the compressed air tank 172 in communication with the conduit 35 so that the pneumatic cylinders 35 receive the compressed air to move the piston rods 34 to the left, as viewed in Figs. 1 and 2, and thus at this time the pair of gripping means are actuated so that the workpiece becomes gripped at it sends adjacent the electrodes. It will be noted that the conduit 36 has branches to both of the units 9 and lli), so that the gripping takes place simultaneously adjacent to both electrodes. As is also apparent from Fig. 1, conduits 62 branch from the conduits 36 associated with the unit 9, so that the pneumatic cylinders55 shown in Fig. 3 receive air under pressure to cause the piston rods 57 to be shifted in a direction which causes the sleeve sections 46 to move toward the sleeve sections 44, so that at this time the pair of sleeve means grip the pair of conductors 64 to provide the electrical connection to the left electrode 7 shown in Fig. 1.

It is apparent, therefore, that when the pressure of the compressed air supplied to the conduit 76 to the cylinders 66 and 8S builds up to a predetermined value, the relay will be energized so as to cause the transformer to become energized, so as to cause the cooling water to start to be delivered, so as to cause the gripping means to become actuated for gripping the opposite ends of the workpiece, so as to cause the contact sleeves of the unit 9 to engage the pair of conductors 74, and so as to cause the valve 101 to be actuated to reverse the direction of the compressed air so that the compressed air now flows through the conduits 75 to the opposite chambers of the cylinders 66 and 88, so that these cylinders together with the bar 13 and the elongated housing 36, respectively, are now urged apart from each other so as to place the workpiece which is gripped by the pair of gripping means 8 under tension. Therefore, with the structure of the invention even if the workpiece 1 should be of such long slender dimensions that due to the pressure applied on the ends of the workpiece by the electrodes 7 this workpiece would bend upon being heated to the desired temperature, such bending cannot take place because the ructure of the invention automatically maintains the workpiece under tension while it is being heated and while at the same time the electrodes are pressing with the desired force against the ends of the workpiece.

All of the current is conducted through the workpiece 9 through the medium of the electrodes 7. Because of the above-described insulating arrangement, the pair of gripping means at each end of the workpiece are protected from the current and do not participate in the conducting of the current through the workpiece.

During the heating of the workpiece by the conducting of current therethrough, and particularly at the beginning of the heating of the workpiece, a certain amount of the material at the end faces 6 of the workpiece will be burnt off, and at this time the structure operates automatically to compensate for this loss of material at the electrodes and to maintain the electrodes and the end faces of the workpiece in engagement with each other with the proper pressure. Thus, an unillustrated valve is located in the branch of the conduit 75 which leads to the cylinder 88, and in this way the pressure which urges the cylinder 88 to the right, as viewed in Fig. 1, in order to maintain the workpiece under tension is regulated. Of course, although the cylinder 66 is also urged to the left, at this time, it does not actually move because of the fact that the pair of sleeve means 44-46 of the unit 9 are in gripping engagement with the pair of stationary electrically conductive rods 64 at this time. Thus, by adjusting the valve carried by the conduit 75 leading to the cylinder 88, his possible to provide through the pneumatic cylinders 35 a pressure greater than that which urges the cylinder 88 to the right in order to maintain the workpiece under tension. Thus, both of the units 35 of the assembly 9 have a total force greater than that urging the cylinder 88 to the right, and the same is true of the pneumatic cylinders 35 of the unit 10. Therefore, the pneumatic cylinders 35 of the unit 9 overcome the force urging the cylinder 88 to the right and pull the workpiece to the left so as to maintain its left end face in engagement with the left electrode 11, and in the same way at the right end of the apparatus, as viewed in Fig. 1, the pneumatic cylinders shift together with the entire unit 10 and the elongated housing 86 to the left, as viewed in Fig. 1, so as to maintain the right electrode 7 with the desired pressure in engagement with the right end face 6, even if material of the latter should burn away. Thus the elongated housing 86 although it is urged to the right, as viewed in Fig. 1, through the air under pressure in the right chamber of the cylinder 88, nevertheless yields and moves to the left by a distance equal to the axial distance of the material which burns off from both the left and right ends of the workpiece, and in this way proper electrical contact is maintained while at the same time the workpiece is maintained under tension.

Thus, this valve in the conduit 75 leading to the cylinder 88 may be set to adjust the tension of the workpiece so as to prevent the bending thereof, and if desired the valve may be adjusted so that there is no tension on the workpiece.

As may be seen from Fig. 1, a pyrometer 1.77 is located adjacent to the workpiece for sensing the temperature thereof. Although this pyrometer 177 and the amplifier 179 which is electrically connected therewith is shown in the drawings schematically as being located over the workpiece, this is only for the sake of clarity, and actually the pyrometer is positioned at the side so that there is sufiicient clearance for the workpiece to be moved to and from the rollers 2. The pyrometer is carried by a bracket 178 which is supported by a stationary part of the machine, The pyrometer maybe set so as to energize the amplifier 179 and a relay 180 electrically connected therewith when the workpiece reaches a predetermined temperature of, for example, 1100 C. Therefore, when this temperature is reached, the pyrometer 177 acts through the amplifier 179 to energize automatically the relay 180, and this relay includes the normally closed switches 180a at 1801;. Therefore, when the relays become energized both of these switches open. The result is that the opening of the switch 130a deenergizes the relay 105, and as a result the switches 105e, 105b, 105d and a all open, while the switches 105a and -105f return to their closed positions. The result is that the valve 173 is actuated to release the pair of gripping devices, the valve 174 is actuated to stop the flow of cooling water, and the circuit of the primary coil of the solenoid 1'70 is interrupted so that the current stops flowing through the workpiece.

Of course, simultaneously with the reversal of the pistons in the cylinders 35 to release the pair of gripping means, the pair of sleeve means which grip the rods 64 also become released. It will be noted that the pneumatic air fed to the cylinders 66 and 88 through the conduits '75 is still in the cylinders and urges them apart from each other, so that immediately upon release of the pair of sleeves 44, 4-6 from the pair of rods 64, the bar 18 is moved to the left, and upon release of the gripping means of the unit 10 the bar 86 moves to the right, so that the workpiece is automatically released and ready to be removed from the apparatus and replaced by another workpiece, as soon as the relay 180 is energized in the manner described above. The removal of the workpiece from the apparatus causes the switch 99 to open so that even though the pyrometer no longer is acted upon by the heat emanating from the workpiece, nevertheless the relay remains unenergized. Of course, the energizing of the relay opens the switch 180b, so that the relay 100 remains unenergized to prevent the switches 100a and 1001: from assuming a position which will cause the parts 13 and 86 to move toward each other. It is only when the workpiece is first placed on the machine that the relay 100 is energized in order to close switch 100a and open switch 10% so as to cause the parts 13 and 86 to move toward each other. Thereafter, while the relay 105 is energized the switch 105] is opened so as to maintain the relay 100 energized, and at the end of the operation while the relay 180 is energized the switch 18% is open so as to maintain the relay 100 unenergized.

As soon as a heated workpiece is removed from the apparatus a new workpiece can be placed therein, by lowering the same onto the machine, and the above operations are repeated. it should be noted that when the gripping devices release the workpiece the springs 26 again assume a position determined by the pneumatic cylinders 35 together with the pistons therein. Also, where the new workpiece has a length which is greatly different from that of the previous workpiece, the entire carriage 74 may be shifted to accommodate such a workpiece, through the action of the pinion 83 and rack 81, referred to above.

Another embodiment of the invention is shown schematically in Fig. 4 and in detail in Fig. 5. In Fig. 4 the structure for supporting the workpiece as well as the electrical circuit and the pneumatic circuit are not illustrated.

Referring now to Fig. 4, the workpiece 1 is placed in the apparatus and has its ends located in the units 192 and 193, these units respectively having electrodes 194 which engage the ends of the workpiece. Each of the electrodes is carried by a housing 204, and this housing is provided with a flange 206 intermediate its ends, this flange being stationary withrespect to the housing 204. The rear end portion of the housing forms a cylinder 208 having chambers 231 and 229 respectively located on the opposite sides of the piston 209 in the cylinder 208 of each of the units 192 and 193.

A plurality of springs 207 are distributed about each of the housings 204 and these springs each press with one end against the flange 206 and with its opposite end against a carrier ring 203 which is thus urged away from the flange 206 toward the workpiece. Each of the rings 203 carries a wedging means 195 having wedging surfaces which cooperate with wedge members 196. These wedge members 196 have free end portions 198 connected in the manner shown in detail in Fig. 5 and described below with an end wall 199 of a frame. so that rods 2% extending through openings of the plate 211% a eless the wedge members 196 are capable of moving toward and away from the workpiece but are nevertheless in a fixed axial position with respect to the wall 199. Each of these walls 199 form part of a frame which includes and connected at their rear ends to another wall 221 of the frame, and each of these walls 2&1 is fixedly connected with the piston rod 211 of the piston 239 in each of the cylinders 2123, this piston rod extending fluid-tightly through. the rear wall of each of the cylinders 2&8.

The left unit 192 has fixedly connected to rear wall 201 an elongated cylinder 223 provided with wall 218 through which a piston rod 217 extends in a lluidtight fashion, and this piston rod 217 fixedly carries a piston 21d which is located within the c. amber 22% of the cylinder 215. piston rod 2-17 fixed to a stationary part 219 of the machine.

The unit 193 includes an eye 220 fixed to its end wall 261 and cooperating with one end of a spring which is hooked onto the eye 22%, at the other end of he spring being hooked onto an eye 22-2 of a static- .ry part 223 of the machine. This stationary part 223 is fixed with a support 224 which carries a stationary switch member adapted to cooperate with. movable switch member 226 carried by a bar 227 fxed to and extending rearwardly of the wall .21 1 of the frame of the unit The circuit for the electrodes is shown schematically in Fig. 4 by the arrows 191, the left arrow 191 showing the circuit connection with a sleeve means 213 corresponding to the above-described sleeves i i, 46. This sleeve means is adapted to be actuated so as to grip the cylinder 2%? of the unit 192 in a manner described below in connection with Figs. 6-8 where the sleeve means 213 is shown in detail. The parts 214 which is fixed with the cylinder 208 of the right unit 193 is connected with flexible copper laminations similar to the laminations of the embodiment of Fig. 1, and cooperating in the same way with a transformer. Thus, the circuit of the embodiment of Fig. 4 is much the same as that of Fig. l.

The rear walls of the cylinders 208 through which the piston rods 211 extend are shown at 212, and each of the units includes adjacent to the electrode 194 thereof a flange 205 fixed to and extending from the electrode carrier 204 for the purpose of limiting the extent of movement of the rings 203 under the influence of the springs 207.

The structure is shown in Fig. 4 in the position it take when the spring 221 has been tensioned and the contact 225 engages the contact 226. When the parts are at rest the rear wall Ztli of the unit 193 engages the left end of the member 224, as viewed in Fig. 4, so as to limit the extent to which the spring 21 moves the unit 193 to the right to its rest position, and in this position the lower end of the wall 201 has the dot-dash line position shown in Fig. 4, while the movable contact 226 has the dot-dash lin os tion shown in Fig. 4 where it is spaced to the right from the stationary contact 225.

When the structure of Fig. 4 is at rest the piston 216 is located at the right end of the cylinder 215, and the wall 201 of the unit 193 engages the member 224, as described above, so that there is sufiicient room for the workpiece 1 to be lowered into the machine to rest on rollers such as the rollers 12. described above. This positioning of the workpiece on these rollers closes a switch such as the switch 99 of Fig. 1 in order to control a valve which introduces air under pressure into the chamber 228 of the cylinder 215, so that the unit 192 is advanced to the right, as viewed in Fig. 4, and this results in the automatic location of the pair of gripping means formed by the wedge members 196 and the wedge housing means 195, 20-2 around the ends of the workpiece, and at the same time the electrodes 194 are pressed against the ends of the workpiece.

When the pressure in the chamber 228 builds up to a predetermined value, a switch similar to the switch 1% of Fig. 1 is automatically actuated in response to this pressure to cut off the flow of compressed air to the chamber 228 and to render this chamber without any pressure. At the same time air under pressure is automatically introduced into the chambers 229 of the cylinders 203. At the unit 192, since the cylinder 208 cannot advance to the right, the piston 269 is moved to the left so as to cause the entire frame made up of elements 201, 200, and 199 of the unit 192 to move to the left, and in this way the wedge members 196 of the unit 192 are shifted to the left with respect to the wedge housing parts 197, 195, 232, and thus the workpiece is automatically gripped at its left end, as viewed in Fig. 4. At its right end, it will be noted that the frame 201, 201i, 199 can move no further to the right, so that the build up of pressure in the chamber 229 causes the entire cylinder 2G8 together with the electrode 194 and the workpiece 1 to shift to the left, as viewed in Fig. 4-, and as a result the Wedge housing 197, 2112 shifts to the left with respect to the Wedge members 196 of the right unit 193 in order to place these wedge members in gripping engagement with the right end of the workpiece. Of course, the entire unit 192 participates in the leftward movement of the cylinder 208 and electrode 194 of the unit 193, because the workpiece 161 is itself shifted to the left, but the piston 209 of the unit 192 nevertheless moves to the left with respect to the cylinder 268 of this unit so as to cause the workpiece to be gripped at its left end as well as at its right end.

When a predetermined pressure has been reached in the chambers 229, so that the workpiece is reliably gripped at both of its ends, another switch which responds to pressure in the same way as the switch 104 of Fig. 1 is automatically actuated to cause air under pressure to be introduced into the chamber 230 of the cylinder 215, and thus this cylinder 215 together with both of the units 192 and 193 which grip the ends of the workpiece are shifted to the left as to tension the spring 221. This action continues until the movable contact 226 engages the stationary contact 225, and this causes the sleeve means 213, which up to this time has not engaged the cylinder 2% of the unit 192, to become automatically moved to a position gripping the cylinder 208 of the unit 192, so as to prevent further movement of the cylinder 2113 of unit 192 and so as to establish an electrical connection through the cylinder 26% and electrode carrier 294 of unit 192 with the electrode 194 thereof, so that at this time the electrical connection through the sleeve means 213 with the unit 192 is established, and the cylinder 208 as well as the electrode 194 of the unit 192 cannot move further to the left, even though there is still air under pressure within the chamber 230.

At the same time, the closing of the switch 225, 226 energizes the transformer so as to complete the circuit through the electrodes 194 and the workpiece 1, and the latter starts to heat up.

In the event that material at the ends of the workpiece 1 become burned on due to the heating up of the workpiece, as was described above in connection with the embodiment of Figs. 1-3, the air under pressure within the chambers 229 of the cylinder 208 will automatically shift the electrodes toward the ends of the workpiece to maintain the electrical connection therewith as well as to maintain the desired pressure between the electrodes and the ends of the workpiece, and at this time the springs 237 become compressed to a greater extent, in exactly the the desired pressure even though material at the ends of the workpiece should burn off, particularly at the beginning of the heating process.

A suitable pyrometer is provided with the embodiment of Fig. 4 in the same way as with the embodiment of Fig. l to sense when the desired temperature of the workpiece has been reached, and when this temperature has been reached the pyrometer automatically causes the circuit or the transformer to be opened, and at the same time it causes the sleeve means 213 to be moved to its inactive position where it releases thecylinder 208 of the left unit 192 of Fig. 4. Furthermore, the chambers 229 of the cylinders 208 are cut off from the supply of compressed air and are rendered pressureless while the chambers 231 and 210, respectively, are provided with the air under pressure, so that gripping means automatically becomes released in order to release the workpiece. Furthermore, air under pressure which at all times during the operation has been in the chamber 230 but was incapable of shifting the cylinder 215 to the left, as viewed in Fig. 4, because of the engagement between the sleeve means 213 and the cylnider 208 of the unit 192 is now capable of shifting the entire unit 192 to the left, as viewed in Fig. 4, and the spring 221 is capable of returning the unit 193 to its rest position, so the the parts move away from the ends of the heated workpiece to enable the latter to be removed from the apparatus and replaced by another workpiece with which the above operations will be repeated.

. It should be noted that the position of the stationary contact 225 or the position of the movable contact 226 on its arm 227 is adjustable so that the tension of the spring 221 when the contacts 225 and 226 engage each other can be regulated in accordance with the type of workpiece which is being handled so that the desired tension may be provided in accordance with the particular dimensions of the workpiece and the extent to which it is to be heated.

Referring now to Fig. 5, wherein only the unit 192 is shown in detail, it will be seen that the carrier ring 203 has the arm 202 of the wedge means fixed thereto while being insulated therefrom through a suitable layer of insulating material located between the ring 203 and the arms 202, as indicated in Fig. 5. These arms 202 terminate in the portions 197 which have wedging surfaces which cooperate with the outer wedging surfaces of the gripping members 196, respectively, and as may be seen from Fig. 5 the elements 198 are substantially L-shaped and extend into an annular groove 241 formed in the end wall 199 of the frame which includes this wall 199 as well as the pull rods 200 and the rear wall 201, as described above. The radial depth of the groove 241 is made especially large to accommodate the radial movement of the wedge members to and from the workpiece, and any suitable spring means may cooperate with the wedge members to urge the latter away from the workpiece, so that when the elements 199 and 202 are not urged toward each other the wedge members 197 will automatically move away from the workpiece.

. It will be noted that the arms 202 additionally serve to support a tubular ring 248 which forms a conduit for a cooling fiuid which is sprayed through suitable nozzles formed by openings of the tube 248 onto the end of the workpiece as well as onto the electrode 194, and the housing 204 which carries the electrode 194 is hollow and may receive the cooling fluid in its interior before this cooling fluid reaches the cooling tube 248. in this way the inner end of the electrode 194 which extends into the hollow housing 204 is also cooled. The portions 197 of the wedge means are formed with grooves 24-0 which receive mating portions of the wedge members 196.

1 As may be seen from Fig. 5, the forward portion of the cylinder 208 forms an elongated electrically conducted bar 249 into the right end of which the electrode carrier 204 is threaded, and the flange 206 is integral with the housing 204 and urges the springs 207 to press the ring 203 to the right, as viewed in Fig. 5, this spring being slidableon the exterior surface of the housing 204. The flange 205 is shown in Fig. 5 as taking the form of a snap ring which snaps into an annular groove formed in the outer surface of the housing 204 adjacent its right end, as viewed in Fig. 5, so that this snap ring 205 limits the movement of the ring 203 to the right, as viewed in Fig. 5, with respect to the housing 204.

The ring 203 is provided in its bores through which the pull rods 200 extend with suitable bearing sleeves 243 which slidably bear against the rods 200, and furthermore at its top end the ring 203 is connected with rollers 247 which roll along tracks 245 carried by a cantilever arm 246 of a carriage 219 which is provided with rollers 261 guided on suitable tracks. This carriage 219 is provided with a pinion 264 operated through any suitable worm and worm gear transmission so that this transmission is irreversible in order to maintain the pinion 264 in the positon to which it has been turned, and this pinion 264 is turnably carried by the carriage 219 and meshes with a stationary rack'so that in this way it is possible to position the carriage 219 at a desired position to accommodate workpieces of widely different lengths.

The left end wall 201 of the frame is fixed by the nuts 242 with the left ends of the pull rods 200, and nuts 242 also serve to connect the right end of the pull rods 200 with the right end wall 199 of the frame. The portions of the pull rods 200 which extend into the bores of the end walls 201 and 199 are located in insulating sleeves.

The carriage 219 carries pins 254 on which a plurality of rollers 253 are turntable, and these rollers cooperate with the cylinder 215 to guide the latter for movement to the right and left with respect to the carriage. This cylinder 215 has its right end wall 251 fixedly connected by a. nut 252 with the piston rod 211 which carries the piston 209 located within the cylinder 208, and this cylinder is slidable in a bore formed in the right end of the rod which forms the cylinder 215. The rear wall 258 of the carriage 219 is formed with an opening through which the cylinder 215 freely passes, so that in this way the parts are free to shift to the right and left, with respect to the carriage 219. This carriage fixedly carries an elongated tubular housing 255 which has its left end wall fixedly connected by the nuts 256 with the piston rod 217 which thus remains stationary with respect to the housing 255 and the carriage 219, and this piston rod carries the above-described piston 216 which slides within the cylinder 215, the piston rod 217 extending fluid-tightly through the end wall 218 of the cylinder 215 which is threaded onto the cylinder 215 in the manner shown in Fig. 5.

A pair of pneumatic conduits 260 communicate with the left end of the piston rod 217 so as to supply the air under pressure to a pair of bores which pass through the piston rods 217 in a manner shown in Fig. 5, one of these bores passing completely through the piston 216 so as to supply compressed air to the chamber of the cylinder 215 which is to the right of the piston 216, and the other of these bores communicating with the chamber in the cylinder 215 which is located to the left of the piston 216.

In the same way a pair of conduits 259 communicate with bores of the piston rod 211, one of these latter bores extending completely through piston 209 so as to provide communication with the chamber of cylinder 208 which is to the right of the piston 209, and the other of the bores of the piston rod 201 communicates with the chamber of cylinder 208 which is to the left of the piston 209. The portion 250 of the rod which forms the cylinder 215 is separated from the interior of the cylinder 215 by the partition 251 to which the piston rod 211 is fixed by the nut 252, as described above, and in addition this portion 250 is formed with an axial slot 15 through, which the: conduits 259 extend, as, shown in Fig. 5.

Fig. 5 also illustrates the sleeve means 213 the details of which are described below, and Fig. 5 shows the structure for preventing axial movement of the sleeve means 213 while permitting radial turning movement of the two halves of the sleeve means one with respect to the other. The portion 249 of the unit shown in Fig. 5 is gripped by the sleeve means 213 in order to prevent further movement of the portion 249 even though there is still air under pressure in the cylinder 215 in the chamber to the left of the piston 216, and the gripping of the sleeve means 213 with the portion 249 establishes part of the electrical circuit to the electrodes 194.

The arrangement of the insulating sleeves n the right ends of the pull rods 2% to insulate them from the end wall 199 as well as the arrangement of the insulating layers between the arms 202 and the carrier plate 293, insulates the wedge members from the electrical circuits so that the gripping means cannot carry any of the electrical current. i

It will be noted from Fig. 5 that the portion 249 as well as the cantilever arm 246' are made relatively long in order to enable the apparatus to handle workpieces of widely different lengths. The same is true of the relatively long length of the pull rods 2%.

The operation of the structure of Fig. 5 has been described above in connection with Fig. 4. The details of the sleeve means .213 are shown in Fig. 6, and the details of the structure for actuating the sections of the sleeve means 213 are shown in Fig. 6 also, another embodiment of a structure for actuating the sections 82 of the sleeve means 213 being shown in Figs. 7 and 8 and being de scribed below. The embodiment of Figs. 7 and 8 is shown used in the structure of Fig. 5.

It should be noted that the gripping members 196 have directed toward the surface of the workpiece surfaces of the same configuration as the workpiece so that there is a large area of contact between the Wedge members and the work Jiece.

Referring now to Figs. 5 and 6, the electrically conductive sleeve means 213 which surrounds the bar 249 is composed of a pair of semi-circular halves 82 respectively carrying at the top ends a pair of axially extending pivot pins 89, and a p urality of cross members 81 are provided and are formed with bores through which the pins 89 extend, so that in this, way the sleeve halves 82 are pivotally connected to each other at their top ends for turning movement one with respect to the other.

These sleeve halves 82 are provided with bottom free ends 83, respectively, and each of these bottom free ends is of substantially U-shaped cross section. The free end at the bottom of each sleeve half 82 is thus formed with a pair of downwardly extending legs, and each of these legs turnably supports a pin 347whose axis is parallel to that of the bar 249.

Referring now to Fig. 6, each of the sections 82 of the sleeve means 213 is provided at its inner surface which engages the bar St? with a plurality of grooves 119 which are circular and ext nd about the axis of the sleeve means. As a. result of these grooves, when the sleeve means clamps the bar 249, the lubricant on the latter can enter into the grooves and the relatively small metallic areas between the grooves 110 at the inner surface of the sleeve means 213 can penetrate through the lubricant into direct metal to metal contact with the exterior surface of the bar .246, so that in this way the resistance at the connection between the sleeve means and the bar 249 is greatly reduced. As a result, the sleeve means 213 does not necorne heated to any appreciable extent.

in the construction illustrated in Fig. 6, each section 32 of the sleeve means has fixedly connected thereto five closely spaced conductors 78. These conductors are fixed to the sleeve sections by bolts 111 which press washers 112 against the conductors, these washers 112 having at their faces which engage the conductors concave recesses into which the conductors fit, as shown. in Fig. 6. Moreover, it will be noted that the exterior surfaces of the sections 82 are formed with recesses into which the conductors 78 extend, so that there is a considerable area of contact between the conductors and the sleeve means 213, and in this way the resistance at the connection between the conductors 78 and the sleeve means 213 also is maintained at a relatively low value. It will be noted from Fig. 6 that the conductors 78 are arranged in two groups on both sides of the axis of the sleeve means 213, so that these conductors which extend parallel to the axis of the workpiece are arranged in two groups along the workpiece on opposite sides thereof in a manner whi h provides sufiicient room for the workpiece to be moved without any inconvenience up or down to or from the machine.

As may also be seen from Fig. 6, screws 113 fix to the lower ends 83 of the sleeve sections 82 shell members 114 which cooperate with the lower free ends 83 to form bearings for .ie elongated pins 34, one pair of these pins being coaxially carried on each of the sleeve sections 82. Each pair of coaxial pins 84 is fixedly connected with a nut 115. These nuts 115 cooperate threadedly with the threaded end portions 116 and 117 of a one-piece spindle 113 which extends between the lower free ends 83 of the sleeve sections 82. The threaded portion 116 of the spindle may have a right hand thread and the threaded portion 117 may have a left hand thread, or the reverse may be provided. The crank 87 has a circular end portion through which the spindle 118 extends, and this crank is turnable with respect to the spindle 118 until the crank is placed in driving engagement with the spindle 118 in a manner now to be described. The intermediate portion of the spindle 113 which extends through the circular end of the crank 37 is provided with an annular flange 119 having a toothed face directed toward the circular end of the crank 87. This circular end of the crank 87 also has a toothed face directed toward the toothed face of the flange 119. Thus when the teeth of the flange 119 mesh with the teeth of the crank 87, the parts are in driving engagement with each other and the turning of the crank 87 by a suitable pneumatic system will be transmitted to the spindle 118. The spindle 118 carries a washer 121 in engagement with the circular end portion of the crank 37, and the intermediate portion of the spindle 118 is provided with a threaded surface receiving a nut 122 which may be tightened so as to place the crank 37 in driving engagement with the spindle 118 and so as to maintain the crank 87 in such driving engagement with the spindle 118.

At its opposite sides a guide plate 93 supported by a stationary machine part is provided with threaded eyes 123 through which screw members 124 threadedly extend. The axial positions of these screw members may be adjusted so that their free ends cooperate with the lower free ends 83 of the sleeve sections 82. Thus, the screw members 124 are adjustable stops which can be set to limit the extent of turning movement of the sections 82 of the sleeve means 79. If one of the ends 83 of the section 82 engages the pins 124, then the particular section can turn no further and a continued turning'of the spindle 118 will guarantee that the other section of the sleeve moves away from the bar 249 until the bottom free end portion 83 of this other sleeve section engages the other stop 124. In this way it cannot happen that one of the sleeve sections 82 remains in engagement with bar 249 while the other sleeve section moves away from the latter to an undesirably large extent.

Instead of interconnecting the sleeve sections through pivot pins and cross pieces 81, the top ends of the sleeve sections may be provided respectively with knoblike bosses which extend into a hollow hood-like member which interconnects these knob-like projections for turn- 17' iris movement with respect to each other, so that in this Way the sections may be connected together without the use of elements such as pivot pins 80. The movement of the sections 82 of the sleeve means 213 toward and away from each other may also be brought about with the structure shown in Figs. 7 and 8 instead of the structure shown in Fig. 6. In this embodiment the lower ends of the sections 82 are in the form of elongated member 125 which are inclined with respect to each other in the manner shown most clearly in Fig. 8. Each of these free ends 125 of each sleeve section is located between a pair of parallel sets of rollers 126. Each row of rollers 126 is carried by a cage 127, and the cages 127 are carried by a member 130 which takes the place of the member 93 of the embodiment of Figs. 5 and 6. The surfaces 128 and 129 of member 130 along which the rows of rollers 126 are arranged have the same inclination as the elongated lower end portions 125 of the sleeve sections 82, respectively.

The member 130 is moved in one or the other direction by a piston rod 133 which has its flange 132 fixed to one end of the member 130 by the screws 131. This piston rod 133 is fixed to a piston 134 located within a stationary cylinder 137 having end walls 135 and 136. The end wall 135 is formed with a passage 138 leading into the interior of the cylinder and this passage 138 is connected with a compressed air conduit, while the end wall 135 is formed vvitha passage 139 also leading to the interior of the cylinder, and this passage 139 is connected with another compressed air conduit. Therefore, when a pressure-responsive valve is actuated in the manner described above the piston rod 133 will be moved inone direction or the other so as to shift the member 130 in the direction of the axis of the sleevemeans for opening orclosing the latter, and any suitable stop members engage opposite ends of the sleeve means to prevent axial shifting thereof during the axial shifting of the member 130, so that in this way the sections 82 are moved toward oraway from each other with the embodiments of Figs. 7 and 8.

Inasmuch as the sheared end faces of the workpiece I do not necessarily extend perpendicularly to the axis of the workpiece, the electrode carrier structure shown in Fig. 5 is to be considered as schematic. The details of a suitable electrode carrier structure which enables the electrodes to adapt themselves to the inclinations of the end faces of the workpiece is illustrated in Figs. 9 and 10.

Thus, referring ,to Fig. 9, it will be seen thatthe elongated hollow bar 249' is threadedly connected with a plurality of elongated studs 140 which extend to the right, as viewed in Fig. 9, beyond the right end face of the bar 249, and these studs 140 extend respectively through axial bores of a socket member 142 of a ball and socket joint shown in Fig. 9. The ball member 141 of the ball and socketgjoint is shown within the socket member142. This member 142 forms a part'of a cast electrically conductive housing 143 which'threadedly carries atits left end, asviewed in Fig. 9, an electrically conductive member 144 whichfincreases the area of contact between thegbar 249 and the electrode, carrying structured Themember 144 isformed with a central pin 145 which extends into a mating recess in, the right end face of the bar 249, and the right surface of the plate 144, as viewed in Fig. 9, presses against a rearwardly directed extension 146 of the'socket member 142. The studs ll40-threadedly carry a plurality of 'nuts 147 which serve to press against the right annular surface of the socket housing 143 a securing ring 148 which secures the.

ball member 141 within the socket member 142, and this" ring 148 is provided with an annular felt ring 149 which engages the exterior surface of the ball member 141. Thisring 149-acts as a sealing ring to retain lubricant within the ball and socket joint. I

-The electrode carrier itself includesan annular flange 150 zfixedly connected with the ball member 141,.and the electrode carrier has a cylindrical portion between the terior 153 of the electrode carrier, and the electrode 152 is threadedly connected with the flange so as to close the opening thereof. The electrode 152 is preferably of hexagonal configuration so that it can be tightened and loosened by applying a wrench to the electrode 152. The flange 150 is formed with a pair of bores 154 and leading into the hollow interior 153 of the electrode carrier, and these bores 154 and 155 are threaded at their outer ends so as to receive nipples for connecting with these bores the cooling water conduits which operate in the manner described above. 7 I

With this ball and socket type of support for the'electrode, the electrode is capable of adapting itself to the inclination of the end face of the workpiece, and a means is provided for releasably retaining the electrode in a position where it is perpendicular to the axis of bar 249 when the electrode is not in engagement with the workpiece; This means includes the ends 156 of the studs 140, these ends 156 being rounded and of a substantially dome-shaped configuration. These ends 156 respectively extend into recesses 157 of a plurality of pins 158 which are slidable within axial bores of the flange 150, respec tively. Each of the pins 158 has an elongated portion 159 of reduced cross section which extends slidably into the axial bore of a member 161 which is threadedlycarried by the bore of the flange 150 which slidably receives the iarger portion of each pin 1 58, and a coil spring 160 is coiled about the portion 159 of each pin and presses at one end against the member 161 and at its opposite end against the annular surface of each pin 158 which is located between the larger and smaller portions thereof.

Thefree right endsof the members 160 are of hexagonal configuration so that these members 1 60 may be conveniently turned by the screw or the like. The springs 160 act to return the electrodes to a predetermined po-'' sition with respect to the axis of the bar 249 whenever these electrodes do not press against the end face of the workpiece. Moreover, the screw members 161 are set to prestress the springs 160 so as to compensate for the weight of the electrode and its carrier structure. 7 the lower member 160 will be turned so as to compress the lower spring 160 to a greater extent than the upper spring, and in this way this lower spring is able to take care of the weightof the electrode and its carrier which would tend'to turn the electrode downwardly through a predetermined angle if both the upper and the lower springs were prestressed to the same extent. Moreover, the ends 156 of the studs 140 cooperate with therecesses 157 to prevent turning of the electrode and its carrier.

structure about the axis of the bar 30.

may accumulate in and be stored in these grooves.

In the arrangement shown in Fig. 10, the grooves 162 areof circular configuration and are all parallel to 6 each other. It is of particular advantage, however, to

arrange the grooves as shownfor the grooves 163 in Fig. 9. Thus these grooves radiate along meridians from a pair of opposed areas similar to opposite poles of the spherical member 141. With the arrangement shown in Fig. 9 it is possible to use the pole areas at which the ends of all of the grooves are located for the purpose of transmitting a lubricating oil to or from the surfaces of the ball and socket joint, the lubricating oil acting as a cooling liquid in this case. It will be understood that each of the elements described above, or two or more together, may also find, a useful'application in other types of heating apparatus} differing from'the types described above.

While the invention has been illustrated and described meal-1,892:

as: embodied inelectrical heating; apparatus, it: is not intended-to be limited to the details shown, since various modifications and structural changes may be made without depa'rtingin any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:'

1. In an electrical heating apparatus, in combination, a pair of electrodes spaced from each other along a pre determined axis and adapted to press against an electrically conductive workpiece located between and inengagement with said electrodes; support means supporting at least one of said electrodes for movement along said axis toward and away from. the other of said electrodes; moving means cooperating with said one electrode for moving same first toward said other electrode and then away from said other electrode along said axis; and a pair of gripping means located adjacent said electrodes, respectively, for gripping the portions of a workpiece which are adjacent to said electrodes, respectively, to prevent the workpiece from being separated from said electrodes while the workpiece is engaged by said pair of. gripping means, said moving means acting on said one electrode for urging the same away from said other electrode after the workpiece is gripped by said pair of gripping means so that the workpiece is maintained under tension while at the same time being engaged by the pair of electrodes so that current may be conducted through the workpiece to heat the same.

2. In an apparatus for electrically heating an electrically conductive workpiece, in combinatioman electrode adapted to be placed in engagement with a workpiece for establishing an electrical connection therewith; support means supporting said electrode; a pair of gripping mem bers located adjacent said electrode for gripping a workpiece at a portion thereof located adjacent to said electrode when the workpiece is engaged by the electrode; linkage means carrying said pair of gripping members for moving the same into and out of engagement with the workpiece when said linkage means is operated; carrier means carrying said linkage means and connected with said support means for movement toward and away from the same; and means cooperating with said linkage means for operating the same to move said gripping members into engagement with a workpiece and for simultaneously urging said gripping members, said linkage means, and said carrier means carrying said linkage means in a direction which tends to move the workpiece toward said electrode, so that when said support means is urged in said direction the workpiece may be maintained under tension while it is being heated and at the same time the workpiece will be maintained in engagement with the electrode even if part of the workpiece burns away during engagement between the workpiece and the electrode.

3. In an apparatus for electrically heating an electrically conductive workpiece, in combination, an electrode; support means supporting said electrode; means cooperating with said support means for moving the latter together with said electrode, said electrode being adapted to engage a portion of an electrically conductive workpiece to establish an electrical connection therewith; a pairv of gripping members respectively located adjacent said electrode for gripping a workpiece at a portion thereof located adjacent said electrode, said pair of gripping members each having a Wedging surface; wedge means carried by said support means and cooperating with said' gripping members for removingthe same into, gripping engagement with the workpiece when the grip, pingmembers and said wedge means are urged in apredetermined direction with respect to the other; and mov-' ing means cooperating with said gripping members for moving the same with respect to said wedge means in a: direction which moves said gripping members into gripping engagement with the workpiece, so that when the support means is urged in a given direction the work piece will be tensioned while it is simultaneously in engagement with said electrode, said moving means simultaneously maintaining the electrode and workpiece in engagement with each other even if some of the material of the workpiece burns away due to the electrical interengagement between the workpiece and the electrode.

4. In an apparatus for heating an electrically conductive workpiece by passing an electrical current therethrough, in combination, an electrode adapted to engage the workpiece to establish an electrical connection therewith; support means carrying said electrode; gripping means located adjacent said electrode for gripping the workpiece at a portion thereof adjacent the electrode; and actuating means cooperating with said support means and said gripping means for actuating the latter to grip the workpiece.

5. In an apparatus for heating an electrically conductive workpiece by passing an electrical current therethrough, in combination, an electrode adapted to engage the workpiece to establish an electrical connection therewith; support means carrying said electrode; gripping means located adjacent said electrode for gripping the workpiece at a portion thereof adjacent the electrode; and means cooperating with said support means and said gripping means while the latter grips the workpiece for urging said electrode and gripping means toward each other.

6. In an apparatus for heating an electrically conduc gripping means for actuating the latter to grip the work-'- piece and for urging said electrode and said gripping means, while the latter grips the workpiece, toward each other.

7. In an apparatus for heating an electrically conductive workpiece by passing an electrical current there through, in combination, an electrode adapted to engage the workpiece to establish an electrical connection therewith; support means carrying said electrode; gripping means located adjacent said electrode for gripping the workpiece at a portion thereof adjacent the electrode; actuating means cooperating with said support means and said gripping means for actuating the latter to grip the workpiece; expandable and contractable electrically conductive sleeve means connected electrically with said electrode, carried by said support means and being contractable from an inoperative expanded condition to an operative contracted condition engaging an electrical conductor which passes'through said sleeve means and is connected to a source of current; and means carried by said support means for expanding and contracting said sleeve means between said conditions thereof for placing said electrode in communication with the source of current when said sleeve means is in said contracted condition thereof and for separating the electrode from the source of current when said sleeve. means is in said expanded condition thereof.

8. In an apparatus for heating an electrically conductive workpiece by passing an electrical current therethrough, in combination, an electrode adapted to engage the workpiece to establish an electrical connection therewith; support means carrying said electrode; a'pairof gripping members located adjacent said electrode on oppositesides of an axis passing through said electrode and along which the workpiece is adapted to be located; a pair of parallelogram linkages respectively located on opposite sides of said axis and respectively connected with said gripping members for moving the latter toward and away from a position gripping the workpiece; a carrier member carrying said linkages; connecting means connecting said carrier member to said support means for movement with respect to the latter along said axis; a lever fixed to a link of each linkage, said levers extending toward each other and respectively having free ends directed toward each other; and fluid pressure means carried by said support means and operatively connected with said free ends of said levers for simultaneously turning the'latter in opposite directions for actuating said linkages'to move said gripping members, said fluid pressure means also acting through said linkages on said carrier member for urging the latter along said axis to-' ward said support means so that a workpiece gripped by said gripping members will be urged by said fluid pressure means toward said electrode.

9. In an apparatus as recited in claim 8, spring means cooperating with said carrier member for urging the same away from said support means.

10. In an apparatus for heating an electrically conductive workpiece by passing electrical current therethrough, in combination, an electrode having a predetermined axis and adapted to engaged with one of its faces a workpiece located along said axis for establishing an electrical connection with said workpiece; elongated support means carrying said electrode and extending along said axis away from said face of said electrode; a carrier carried by said support means adjacent said electrode and being movable together with said support means and electrode along said axis; a pair of guide members carried by said carrier and extending therefrom toward said axis, said guide members being located on opposite sides of said axis and respectively having wedging surfaces oppositely inclined with respect to each other and inclined with respect to said axis; a pair of gripping members respectively located between said guide members and said axis and respectively having wedging surfaces respectively in slidable engagement with said wedging surfaces of said guide members, so that when one of said pairs of members is axially shifted with respect to the other pair of members said gripping members will be moved into gripping engagement with a workpiece engaged by said electrode; frame means movable along said axis and cooperating with said pair of gripping members for rendering the same axially immovable with respect to said frame means while at the same time freeing said gripping members for movement by engagement with said guide members radially toward and away from said axis; and moving means cooperating with one of the previously mentioned means for axially moving the latter with respect to the other of the previously mentioned means so as to axially move said pairs of members one with respect to the other for placing said gripping members in gripping engagement with a workpiece.

11. In an apparatus for heating an electrically conductive workpiece by passing electrical current time through, in combination, an electrode having a predetermined axis and adapted to engage with one of its faces a workpiece located along said axis for establishing an electrical connection with said workpiece; elongated electrically conductive support means carrying said electrode and extending along said axis away from said face of said electrode; a carrier carried by said support means adjacent said electrode and being movable together with said support means and electrode along said axis; a pair of guide members carried by said carrier and extending therefrom toward said axis, said guide members being located on opposite sides of said axis andn'respectively having wedging surfaces oppositely inclined with respect to each other and inclined with respect to said axis; a pair of gripping members respectively located between said guide members and said axis and respectively having wedging surfaces respectively in slidable engagement with said wedging surfaces of said guide members, so that when one of said pairs of members is axially shifted with respect to the other pair of members said gripping members will be moved into gripping engagement with a I workpiece engaged by said electrode; frame means movable along said axis and cooperating with said pair of gripping members for rendering the same axially immovable with respect to said frame means while at the same time freeing said gripping members for movement by engagement with said guide members radially toward and away from said axis; moving means cooperating with one of the previously mentioned means for axially moving 'the latter with respect to the other of the previously a workpiece located along said axis for establishing an electrical connection with said workpiece; elongated support means carrying said electrode and extending along said axis away from said face of said electrode; a carrier carried by said support means adjacent said electrode and being movable together with said support means and electrode along said axis; a pair of guide members carried by said carrier and extending therefrom toward said axis, said guide members being located on opposite sides of said axis and respectively having wedging surfaces oppositely inclined with respect to each other and inclined with respect to said axis; a pair of gripping members respectively located between said guide members and said axis and respectively having wedging surfaces respectively in slidable engagement with said wedging surfaces of said guide members, so that when one of said pairs of members is axially shifted with respect to the other pair of members said gripping members will be moved into gripping engagement with a workpiece engaged by said electrode; frame means movable along said axis and cooperating with said pair of gripping members for rendering the same axially immovable with respect to said frame means while at the same time freeing said gripping members for movement by engagement with said guide members radially toward and away from said axis; and piston and cylinder means cooperating with said support means and said frame means for axially moving one of the latter means with respect to the other to place said gripping members in engagement with a workpiece.

13. In an apparatus as recited in claim 12, said piston and cylinder means including a cylinder integral with said support means, a piston slidable in said cylinder,

vand a piston rod fixed with said piston and with said frame means.

14. In an apparatus for heating an electrically conductive workpiece by passing electrical current therethrough, in combination, an electrode having a predetermined axis and adapted to engage with one of its faces a workpiece located along said axis for establishing an electrical connection with said workpiece; elongated support means carrying said electrode and extending along said axis away from said face of said electrode; a carrier carried by said support means adjacent said electrode and being movable together with said support means and 23 eleetrede along said aiis; a pair- 6f guide members car i-ied by said carrier and extending therefrom toward said axis, said guide members being located on opposite sides of said axis and respectively having wedging surfaces oppositely inclined with respect to each other and inclined with respect to said axis; a pair of gripping members respectively located between said guide members and said axis and respectively having wedging surfaces respectively in slidable engagement with said Wedging surfaces of said guide members, sothat when one of said pairs of members is axially shifted with respect to the other pair of members said gripping members will be moved into gripping engagement with a workpiece engaged by said electrode; frame means movable along said axis and cooperating with said pair of gripping members for rendering the same axially immovable with respect to said frame means while at the same time freeing said gripping members for movement by engagement with said guide members radially toward and away from said axis; moving means cooperating with said frame means and support means for moving one ,ofthe' latter mere; with respect to the other in an axial direction to place said gripping members in engagement with a; workpiece; and carriage means movable in a direction parallel to said axis and mounting said frame means for movement with respect to said carriage means in a direction parallel to said axis while at the same time supporting said frame means and support means.

15. In an apparatus as recited in claim 10, said carrier being axially slidable on said support means, and spring means cooperating with said support means and carrier for urging the latter in a given axial direction with re-' spect to said support means.

15 References Cited in the file of this patent UNITED STATES PATENTS 2,248,280 Nobiron July 8, 1941 m Barlow ..;....---;.'-i. Apr-

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