US1878810A - Process for effecting the pressing of metals and apparatus therefor - Google Patents

Description

Sept. 20, 1932. G. BENEDETTO 4PROCESS FOR EFFECTING THE PRESSING OF METALS AND APPARATUS THEREFOR 5 Sheets-Sheet l Filed Sept. ll. 1930 IIIl Sept 20, .1932- G. ENEDETTO 1,878,810

PROCESS FOR EFFECTING THE PRESSING OF METALS AND APPARATUS THEREFOR Filed Sept. ll. 1930 3 Sheets-Sheet 2 /Mff/vrdf Sept. 20, f G BENEDTTO 1,878,810

- PROCESS FOR EFFECTING THE PRESSING OF METALS AND APPARATUS THEREFOR Filed septf 11. 1930 3 sheets-sheet :5

' mrs/v raf Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE GIUSEPPE BENEDETTO, 0F NOVARA, ITALY, ASVSIGNOR T0 THE OMES HOLDING COH- PANY LIMITED, OF LONDON, ENGLAND, A BRITISH COMPANY PROCESS FOR EFFECTING THE PBESSING OFr METALS AND APPARATUS THEBEFOB Application `led September 11, 1930, Serial No. 481,334, and in Italy September 14, 1929.

The present invention relates to electric machines for eectin the forgin of metals by upsetting enlarged portions t ereon. It is old to provide a machine comprising an '15A anvil against which a bar or ingot to be upset is pushed while a strong electric current is passed through the bar to heat it.

In apparatus of this kind a common diliculty lies in the fact that the electrical rel() sistance of the work decreases with the increase of cross section brought about during the upsetting operation. Ordinarily the electric current is conducted into the work through the jaws of a vice in which the work .1liV is held and between which and the anvil the upsetting operation proceeds. Close to the vice the cross section of the work is not 1ncreased by the upsetting and therefore at this v point the current density becomes much highl0 er than in the body of the Work and a common trouble in such machines is burning of the metal due to over-heating by the excessive current density at the neck by the vice. This trouble is particularly met with 1n Ina- I chines where the work slides'through the vice jaws during the upsetting operation so that heads of large diameter can be upset. It 1s an object ofthe invention to provide means for overcomingthe said difficulty.

$0 According to the present invention there is provided an electric upsetting. apparatus comprising in combination an anvil, a vice 1n front of the anvil, means forcausing anl electric current to pass throu hwork held between the vice and the anvi means for forcing the work and the anvil towards one anotherffor forming an upset head and means for so regulating the electric current as to prevent substantial increase thereof when the head is formed.

Alternating current supply apparatus designed to give a constant current has been well known for many years and obviously 1t would be within the scope of the kpresent invention to employ any such apparatus which might be found suitable for the purposes of the invention. Preferably, however, according to the present invention'thek means yfor preventing substantial increase of electric 5 current comprises a transformer havmg oneA of its windings (for example the secondary winding) movable relatively to the other and means for yieldingly urging the said movable winding towards the other winding of the transformer.

With the arrangement furnishing current at a fixed intensity, and always not greater than that which the section of the bar will sustain, the heating is conductedwith all security and without fearfof failure. Further, as the stated cause of damage is no longer to be feared one may, from the commencement of the operation, apply the necessary ltension for the normal intensity of the current, shortening the yduration of the operation as compared with the result. High economies ,of current and of labour are thus attained.

The accompanying drawings illustrate the essential parts of an apparatus in accordance with the present invention by way of example and in the drawings Figure 1 is a front elevation,

Figure 2 is a plan,

Figure 3 is a diagrammatic representation of a transformer provided with a movable bobbin and its electric connections to theapparatus shown in Figures 1 and 2, and

Figure 4 is a side elevation partly in sec? tion of one construction of transformer .with a movable bobbin.

` vReferring to Figuresl and 2 the machine comprises a frame 1l having guideways 12 along its upper surface upon which are mounted an anvil slide 13 at one end, a vice slide 14 adjacent to it,a guide vice 15 andv at the other end a hydraulic ram cylinder -16. All these parts except the anvil carrier 13 are movable longitudinally along the guideways.

In the body of the anvil carrier is a vertical bearing to receive a vertical stem which carries a headstock casting 20 having a horizontal bearing having a mandrel 21. The mandrel 21 carries avworm-wheel 22 at oneend which is engaged by a worm 23 operatedby a hand wheel'24 mounted in bearings 25 on the headstock 20.- Thus the mandrel 21 may be rotated as desired and the axis ofthe mandrel may beset at any angle to the guideways 12 by rotating the headstock 20 upon its vertical stem mounting in the carrier 13.

Suitable means for locking the stem of the headstock 2O when set in any desired position are provided and comprise a clamping bolt 26 working' in a slot 27 in the frame 11.

lVithin the mandrel 21 which is hollow there is mounted the stem of an anvil 28 having a working face 29 which is directed t0- wards the right in Figure 1. The anvil 28 is made hollow and provided with water circulating connections to keep it cool, which connections are not shown in the drawings as lthey are of usual construction. They comprise flexible tubes for the conveyance of the cooling water to aud from the movable anvil. The working face of the anvil is made removable from the main portion and is composed of a high conductivity copper-tungsten alloy of a hard and durable kind.

The anvil carrier 13 is insulated from the guideways 12 by interposed insulating material, which however, as it does not have to withstand a high electric potential may be of no great thickness provided it is capable of withstanding the heavy clamping forces necessary to secure the parts together.

The vice carrier 14 is movable along the guideways 12 under the control of a lead screw 17 which is engaged by a wormwheel 18. The wormwheel 18 is rotatable by a worm on the shaft of a handwheel 19 so that the vice carrier 14 may readily be set by the operator at any desired position on the bed of the machine relatively to the anvil.

The vice carrier comprises a fixed lower jaw 30 and a movable upper jaw 31 mounted on a stem 32 projecting from a hydraulic pressure cylinder 33. A return spring 34 is provided to draw the upper vice jaw 31 normally upwards. A pressure supply pipe 35 to the cylinder 33 is provided which is under the control of a two-way valve 36 operated by a control handle 37. By this means hydraulic pressure can be applied from a supply pipe 38 to the cylinder 33, or alternatively the cylinder may be connected through the two-way valve to an exhaust pipe 39. The vice and the carrier therefor are constructed of bronze or other high conductivity material and the same applies to the anvil headstock. These two parts are connected to the secondary terminals 40, 41 of a step-down transformer 42 which is not shown in Figures 1 or 2 but appears in the connection diagram of Figure 3. The transformer may conveniently be located in the base of the machine. A main control switch 44 is provided for the transformer and this is linked by suitable operative connec- 1 tions to a switch control handle 45.

The hydraulic ram cylinder 16 is movable along the guideways 12 by a lead screw 46 and the longitudinal movement is controlled by a handwheel 47 similarly to the handwheel 19 which controls the longitudinal movement of the vice carrier 14. The cylinder 16 operates a ram 48 which engages a cross head 49, mounted to slide along the guideways 12. The cross head 49 carries an interchangeable ram 50 which is intended to abut upon the end of a workpiece held in the vice jaws 30, 31 so that the other end thereof abuts upon the working face 29 of the anvil. The cross head 49 carries slide bars 51 which are attached to cables 52 passing over pulleys 53 and which at their other ends are secured to a counter-weight 54.

rEhe counter-weight 54 not only serves to draw the ram 50 backward when hydraulic y pressure is cut ott from the cylinder 16 but also serves a second useful purpose in that it ensures that there is no backlash in the operative connections between the handwheel 47 and the cylinder 16.

Upon the upper side of the cylinder 16 is a valve box 55 which carries a valve details of which are not shown in the drawings and which may be of any desired type for opening communication between the two sides of a piston working in the hydraulic cylinder 16. lVhen such communication is opened the force on the ram 50 is reduced or equalized and advanced movement caused to cease. To operate the valves in the valve box 55 there is provided an adjustable, screw 56 which is screw-threaded in a movable valve operating portion of the valve box and which passes freely through the cross head 49 to an operating handle 57. A locking handle 58 is provided which serves to hold the screw 56 in any position to which it has been adjusted. The eli'ect of this arrangement is that when the cross head 49 reaches the handle 57 in the course of its forward movement it operates the valve in the valve box 55 and further advance movement of the ram 50 is prevented. Thus the ram can be set to execute a predetermined stroke.

Hydraulic pressure is supplied to the cylinder 16 through a supply pipe 59 having a telescopic section 60 attached to a two-way valve 61. The two-way valve 61 is controlled by a handle 62 and receives hydraulic pressure from the pipe 38 while it is provided with an exhaust connection 63.

Between the vice carrier 14 and the ram 5() i there is located a guide vice 15. The guide vice 15 is not operated and comprises a pair of horizontally movable jaws 64, 65 actuated by a right and left hand screw on the spindle 66 of a hand lever 67. The guide vice may be removed from the machine if short pieces of work are under treatment but for long pieces of work it grips the work close to the ram 50 and holds it central with the end of the ram.

Turning to Figure 3 this comprises a low tension step down transformer 42 as already referred to the secondary of which is connected by the terminals 40, 41 to the vice and the anvil respectively so that electric current can be supplied to heat the work between the vice and the anvil. The primary of the transformer 42 is provided with a number of tappings operated by a hand switch` 68 and is connected to a movable secondary winding 69 of a control transformer 70. The primary winding 71 of the control transformer is connected to the source of electric supply.

The secondary winding 69 is mounted so as to slide freely on a vertical magnetic core 72 and its weight is partly counterbalanced by a counterweight 7 3 connected to the winding through a balance beam 74.

The construction of the movable -bobbin transformer is indicated only diagrammaticall in Figure 3 but is shown in more detail in Fyigure 4.

In Figure 4 the parts are mounted in an oil containing casing 7 5 and the position of the primary windings 71 and secondary windings 69 can be clearly seen, the latter being` slidably mounted on a vertical magnetic core 7 2 as already described. The balance beam 74 is for the sake of compactness divided into two portions 74, 76 which are interconnected by spur-wheels '77, 78. The balance weight 73 is slidably mounted upon the upper section 76 of the balance beam and is connected to an operating chain 79. The operating chain extends around a chain wheel 8() at one end of the beam and a chain wheel 8l at the other. The chain wheel 81 rotates about a vertical axis which intersects the axis of rotation of the spur-wheel 78Y 83 and the end of thek shaft 82 carrying they cross pins is entered within a hollow boss 84 which forms part of the chain wheel 81. The disposition of the parts is such that the cross pins 83 engage the boss 84 loosely at or about the point ofv intersection ofthe axis of the chain wheel 8l and the balance beam 76. Consequently the verticalshaft 82 can rotate the chain wheelnotwithstanding oscillation of the balance beam 76 yabout its axis. The shaft 82 is telescopically connected to a second shaft section 85 operated through a IIooks joint 86 by a handwheel 8T outside the casing. By the described connections a counterweight 7 3 may be pulled by the chain 79 into any desired position .of adjustment along the balance beam 76.

The weight 73 is not adequate to overcome the Weight of the secondary winding 69 but Moreover the anvil :tace ma and reducing the sec- `cylinder 16 may be initially adjusted along the guideways by the handwheel 47. The vice carrier 14 is set at such a distance from the anvil face 29 as to allow room for the head which it is desired to form upon the work.l Current is then switched on by the handle 45 and hydraulic pressure is applied to the cylinder 1.6 by operating the handle 62. As soon as the work becomes sufciently heated by the electric current the ram 50 forcesthe work through the vice jaws with a sliding action and upsets a head between the anvil 29 and the vice jaws. y

Theoperation ofthe transformer 7 0 prevents overheating of the work at the neck be-` tween the vice jaws and the upset head, which would otherwise occur-.owing to the reduction lof resistance which takes placewhen the section of they metal is increased by the upsetting operation. The current can further be hand-controlled by the handle 68 if desired but generally speaking this handle needs only to be set at a different position for diiferent sizes of work, a corresponding alteration in the counterweight 7 3 being effected if desired.

By rot-ating the Working face of the anvil y29 about a vertical axis it can be set to various degrees of inclination to the line of advance of the workpiece and located in this position by the bolt 26. This permits of the formation of lopsided or angularly inclined heads. be rotated in its own plane by operating t e handwheelr24 during or after the upsetting operation. This permits of the production of various twisted shapes. The working face of the anvil may be recessed moreover to further shape the head of the work.

I claim y l. An electric upsetting apparatus comprising in combination an anvil, a workholding vice in front of the anvil, means for forcing work held in the vice so as to extend toward the anvil and the anvil towards kone another for forming an upset head, a

constant current transformer having one of its windings movable relatively to the other under the influence of means for yieldingly urging the said movable winding towards the other winding of the transformer, and means whereby the secondary circuit of the said transformerv may supply electrical energy for heating the work held between the vice and the anvil. f

2. An electric upsetting apparatus rcomprising in combination, an anvil, a vice in l CTI front of the anvil having jaws to hold the work and convey electric current thereto while permitting sliding movement of the work through the vice jaws towards the anvil, a ram to engage the end of the work remote from the anvil and force the work through the vice jaws, means for supplying pressure to the ram, a constant current transformer having one of its windings movable relatively to the other under the influence of means for yieldingly urging the said movable winding towards the other winding of the transformer, and electric connections whereby the output energy of the said transformer is applied to heat the work between the vice and the anvil.

3. An electric upsetting apparatus as claimed in claim l wherein the movable bobbin of the transformer is slidably mounted upon a vertically extending core and an adjustable counterweiglit is provided operatively connected to the bobbin for the purpose described.

4. Electric upsetting apparatus as claimed in claim l wherein the secondary of the movable winding transformer is electrically connected to a step down transformer the secondary of which is electrically connected to the vice jaws and the anvil respectively.

In testimony whereof I aiiiX my signature.

GIUSEPPE BENEDETTO.

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