US2107896A

US2107896A - Metal extrusion press and method of operation

Info

Publication number: US2107896A
Application number: US703057A
Authority: US
Inventors: Edgar W Macknight
Original assignee: General Cable Corp
Current assignee: General Cable Corp
Priority date: 1933-12-19
Filing date: 1933-12-19
Publication date: 1938-02-08
Anticipated expiration: 1955-02-08
Also published as: GB427697A

Description

Feb. 8, 1938.- E. w. McKNl'GHT l 107596 u METAL EXTRUSION PRESS AN) METHOD OF OPERATION Filed Deo. 19, 1935 4 sheets-sheet 1 i 1 4 V ffl? il N l) 54 vif ffy

' BY i @www1/s.-

Feb. 8, 1938. 'E. W. MacKNlGHT 2,107,896

METAL EXTRUSION PRESS AND METHOD OF OPERATION Filed`Dec. 19, 1953 '4 Sheets-Sheet 2 g BY D.

E ATTORNEYS.

. 19, 1935 4 Sheets-Sheet 3 Wm f 5 l .f i f Z 4. 7 a. R n S 5 5 5 f 7 i 4. I a 0 0.@ f w y M y 7 f MM m l E c R @a I H i a m 00%00 5 K nu W I l Hf l W. ...5, m 2 d ,a |I j f I B 7 5 5 L1 I J d 0 l .v 4l. 4J a. m W 1|: Il 4| L una. m5 7 f W i rmx E. W. Maf/KNIGHT Fled Dec Feb. 8, 1938.

yl-"eb. 8,193. EWMMMGHT "2,107,896

METAL EXTRUSION PRESS AND METHODOF OPERATION Filed Deo. 19, 193s 4 sheets-sheet 4 wwwaaaeeam IN V EN TOR.

Patented Feb. 8, 1938 METAL EXTRUSION PRESS AND METHOD F OPERATION Edgar W. MacKnight, Bayonne, N. J., assignor to General Cable Corporation, New York, N. Y., a corporation of New Jersey Application December 19, 1933, Serial No. 703,057

22 Claims.

This invention relates to metal extrusion presses and the method of operating such presses. More particularly the invention is concerned with presses for extruding metal sheaths on electrical cables. Ordinarily, cable sheaths are made of lead or an alloy of lead. It is an object of this invention to provide improved apparatus for extruding metal, and also to provide an improved method of operating such apparatus in which the a press for extrudlng cable sheaths, and of the-l associated metal pot;

Fig. 2 is a top plan view of the bracket |25 shown in Fig. 1;

Fig. 3 is an enlarged vertical section through the upper end of the press cylinder, the lower end of the press ram and the stuiling box connecting these two members;

Fig. 4 is a section substantially on the line 4 4 of Fig. 3; 1

Fig. 5 isvan enlarged vertical section through the upper end of the press ram and the canopy of the press;

Fig. 6 is an enlarged vertical section through a portion of the metal melting pot, showing the metal measuringand pumping device;

Fig. 7 is a section substantially on the line 1- 1 ofFig.6;

Fig. 8 is a section substantially on the line 8 8 of Fig. 6;

Fig. 9 is a vertical section through a valve which, in some cases, may be substituted for the metal measuring and pumping device shown `in Fig. 6;

Fig. l0 is a somewhat diagrammatic showing of apparatus used, for example, with the valve shown in Fig. 9 for measuring and indicating continuously' the amount of metal extruded from the press in an extrusion operation, and also the amountof metal entering the press during acharging operation; and

Fig. 11 is a view of the indicator dial substantially 0n the line lI--Il of Fig. 10. v

In sheathing electrical cables with metal there are two types of vertical presses in general use.

In one of these the press cylinder is stationary press ram is stationary and the press cylinder moves. The present invention is most easily adapted for and is illustrated herein with reference to a press in which the ram is stationary.

The actual extrusion of metal is not continuous in either type of press for the reason that it is necessary to separate the ram and the cylinder and recharge the cylinderrwith metal when a majority of the original charge lof metal has been extruded from the cylinder. In recharging, the cylinder is lled with molten metal, and then it is necessary to wait until the metal cools sufficiently to solidify before the extrusion operation can be continued.

Heretofore it has been the common practice in charging a press cylinder to separate th'e cylinder and the ram, and then to ll the cylinder with molten metal from a nearby melting pot by opening a valve at the bottom of the pot and permitting metal to flow down an inclined trough, the lower ;end of which has been moved overthe open end of the press cylinder. When the cylinder has been filled with molten metal the valve at the bottom of the pot is closed, and an effort is made to remove the dross on the top surface of the metal in the cylinder either by flotation or by skimming. The ram is moved downwardly to seal the charge and then it is necessary to suspend operations until the molten metal has solidied. After solidication of the charge the extrusion operation may be continued.

In operating presses as described above, impurities are accumulated by or formed in 4the molten metal, and also on the exposed surface of the hot metal slug remaining in the cylinder, and on the thin layers of hot metal on the surfaces of the cylinder and ram. Exposure of the molten metal to the air as it issues from the melting pot and flows through the trough to the press cylinder is accompanied by oxidation of the metal. This oxidation results in the formation of dross which is carried into the press cylinder. The upper surface of the slug left in the cylinder at the completion of an extrusion operation also begins to oxidize as soon as the ram leaves it on its up-travel. Likewise the thin lm of metal on the inner surface of the cylinder andthe end of the ram oxidizesl and finds its Way into the charge. This oxidized film tends to prevent perfect welding of the new charge, and While a portion of the oxide may float to the top and be skimmed oif, apart of it will remain in the charge. This oxide may reduce the strength of the bond in the cable sheath. Furthermore,v some metal may cling to the trough at the completion of a chargmg operation'. such metal will oxidize in the air and build up into large particle sizes which will be carried into the cylinder with the molten metal during the next charging operation.

In charging a press in the manner just described the metal which runs into the cylinder strikes the relatively cold wall of the cylinder and freezes in an irregular lump. The surface of this lump lms over instantly and is continuously spattered with more hot metal, forming a larger lump containing oxide and gas bubbles which eventually must appear in the cable sheath. These entrapped air or gas pockets are compressed to very small size during the extrusion operation, and expand again after passing out of the die. If the pocket is near the surface of the sheath it will explode outward and perhaps may be discovered and repaired, but it is just as likely that the pocket will occur adjacent the inner surface of the sheath and burst inwardly, to the detriment of the cable insulation, as well as the sheath. Also there is some danger oi carrying metallic oxide and other dirt from the melting pot and trough into the cylinder.

According to the present invention a commercially practicable method and apparatus is provided for extruding cable sheaths, in which oxidatlon of the slug remaining in the cylinder prior to a charging operation is prevented, and in Which molten metal passes from the melting pot to the press cylinder without exposure to the air or any other gas at any point during its movement. cylinder and lower end of the ram, b'oth of which come in contact with the metal, are not exposed to the air or other gas, and are therefore free Afrom oxides. y

Referring first to Fig. 1, the vertical columns 2 l', four in number, support near their upper ends the press canopy 22, from which depends 'the press ram 23. The ram 23 enters the upper end of the press cylinder24. Secured on the upper end of the cylinder 24, as' by means of the screws v25, is a stuiling box 26 which surrounds the ram.

This stuilng box comprises a seal preventing `access of air into the cylinder, while permitting relative movement between the ram and the cylinder.

In the illustrative embodiment the cylinder 24 rests on a layer of heat insulation 21, on top of a iiow plate 28, which in turn is supported on the die block 29. However, the cylinder may rest directly on the die block 29, either or both the insulation and the flow plate being omitted` The die block 2 9 has a horizontal die opening 38 through which the cable passes during the sheathing operation. The die block rests on 'the upper end of the hydraulic press plunger 3| which may be moved up and down under the action of hydraulic press mechanism not shown here.

'I'he construction of the vlower end of the press ram 23 and of the stuffing box 26 will be better understood by referring to Fig. 3. The stung box comprises the ring-like casting 26 having spaced around its periphery a plurality of holes to receive the screws 25 by means of which it is secured on the upper end of the cylinder 24. An air-tight joint between the top'surface of the cylinder end and the stufiing box is secured by means of the packing ring 32, for example asbestos, positioned in an annular groove on the lower face of the casting 26. When the screws and an air-tight joint is established.

Furthermore the inner surfaces of the The central opening through the casting 26 conveniently is large enough to permit moving it over the lower end of the raml 23. As will appear hereinafter, the lower end of the ram 23 preferably is slightly larger in diameter than the main -body of the ram. The central opening through the casting 26 has al shoulder supporting the packing gland ring 33. The gland ring 33 has a sliding t with the main body of the ram and conveniently may be formed in two pieces to permit assembly about the ram in the stuing box. Desirably the lower edge of the gland ring 33 is inclined upwardly away from the ram so that when the press cylinder is moving away from the ram any metal which might have escaped from thecylinder around the lower end Vof the ram will be shaved oi of the ram, thereby protecting the stuing box packings.

Surrounding the ram and resting on the gland ring 33 are annular packings 34, for example asbestos. Over the packings 34 is the gland 35, also conveniently formed in two'pleces to provide a sliding t with the ram. The gland 35 is forced downwardly to compress the packings 34 between the stuffing box 26 and the ram 23 by means of the ring 36 and the screws 31.

, The arrangement of the stung box just described provides an air-tight joint between the upper end of the press cylinder and the press ram, but does not interfere with free movement between the cylinder and ram in the normal operation of the press.

Means are provided for evacuating the space between the press cylinder andl the press ram under the stuffing box. As shown in the drawings, a pipe 38 is secured in an opening through the wall of the casting 26, and this pipe is connected to evacuating apparatus, for example a pump, not shown. By maintaining a high vacuum within the press cylinder under the ram, oxidation of the slug of metal remaining in the cylinder during a charging operation, and of the molten metal with which the cylinder is charged, are eliminated. Furthermore, the formation of gas pockets or bubbles in the charge is prevented.

The ram 23 has a longitudinally extending central opening 4| which is enlarged for a short distance at the lower end of the ram as shown at 42 in Fig. 3. This enlarged opening 42 is screwthreaded to receive the threaded hub 43 of the end. block 44 for the ram. This end block has a close sliding t with the bore of the cylinder, and conveniently Vis provided with Spanner wrench holes 45 to facilitate securing it into position.

The end block 44 has a shoulder central opening, the lower portion of this opening flaring outwardly, as shown at 46, at an angle of preferably about 45 degrees to provide a. valve seat.

Mounted in the upper portion of the end block 44, and supported on the shoulder, is a tubular metal member 41. The member 41 preferably is flanged at its lower end, and this flange 48 may be separated from the shoulder in the block 44 by means of thermal insulation 49. This insulation 49 conveniently is placed under compression, as by means of the tube 50 loosely surrounding the member 41 and bearing on the outer edge of the flange 48. vThe tube' 50 conveniently is pressed downward by means of a ring 5I and the screws 52 passing therethrough and entering the hub 43. l

The wall of the member 41 desirably is made fairly thin to insure correct heating, as will appear more fully hereinafter. For this reason it may be desirable to reinforce the wall as by means of the surrounding circumferential rings or bands 53. y

The lower portion of the member 41 adjacent its 'anged end is somewhat reduced in diameter as compared to the main body of the member. Loosely mounted in the opening through the end block M is a valve stem l whose upper end desirably is round or pointed, and provided with a spider head having arms 55 which loosely enthe valve sea-t 46, thereby closing the passageway y between the press cylinder and the member 41, and preventing ow of metal outwardly from the cylinder. When the valve stem moves downwardly thisl passagewaywill be open, permitting ilow of molten metal into the cylinder.

Preferably, the valve 56 extends downwardly beyond the lower face of the end block 44 somewhat in the manner shown in Fig. 3. This extension of the valve into the press cylinder constituixes a means whereby the operation of the valve may be controlled automatically by the charge of metal in the cylinder in response to relative movement between the cylinder and the ram. While metal is being extruded from the press the valve is forced upwardly in the valve seat by the pressure in the cylinder and becomes'rmly embedded in the upper end of the charge of metal in the cylinder. When movement between the cylinder and the ram is reversed for the purpose of recharging the cylinder with'molten metal the grip of the metal onthe lower end of the valve 56 is sumcient to pull the valve and valve stem downwardly, thereby opening the valve vbefore and ram move toward each other the valve will which desirably tightly engages the inner wall of the member I1. This plug 6I has a downwardly tapered central opening which receives the tapered lower end of a pipe 62 extending upwardly through the longitudinal opening Il in the ram 2l. p

Referring now to Bg. 5, the'pipe 62 desirably is supported against buckling in its passage upwardly through the press ram and canopy. Conveniently this-support takes, the formof an in- Y sulating bushing 63 surrounding the pipe where the pipe emerges from the ram into the vertical opening 65 in the canopy. The insulating bushing 63 ts loosely about the pipe 62 to permit evacuation of the annular space in the ram through the upper opening in the canopy. The insulating bushing 63 may be held in place by means of a metal ring 64.

The vertical opening 65 in the press canopy is closed at its upper end as by means of a metal plate 66 secured to the canopy with screws 61. Between the canopy and the plate 66 is a compression packing 68 to insure an air-tight joint. The pipe 62 passes outwardly of the canopy through a stuing box an enlarged central opening in the plate 66.

Secured in this opening in the plate 66 is a cup member 69 containing an insulating packing surrounding the pipe 62. Convenientlythis packing may comprise asbestos board bushings 10 between which is a layer 1i of asbestos packing.'

Thev packing is maintained under compression, thereby sealing the passage between the pipe 62 and the cup 69, as by means of a plate 12 loosely surrounding the pipe and forced downwardly against the upper bushing 1li by the screws 13.

It will be apparent from the foregoing description that by means of the Istumng box the joint between the pipe 62 and the canopy 22 may be made airtight, and that the pipe 62 may be inserted or removed merely by loosening the stuffing box connection at the top of the canopy.

A tight connection between the lower end of the pipe 62 and the plug 6l is maintained by pressing the pipe downwardly so that its lower end engages the aperture in the plug 6i with a. tight wedging action. Conveniently, this downward pressure on the pipe 62 may be maintained in the manner illustrated in the upper part of Fig. 5.

Clamped about the pipe 62 a. short ways above the plate 12 are two clips 14. Bearing downwardly on the upper of these clips, but separated therefrom by a block 15 of electrical insulating material, is one end of the lever 16. The other end of the lever 16 rests on a support 11 extending upwardly from the canopy 22. Intermediate its ends the lever 16 is guided vertically by sliding along the pin 18 extending upwardly from the canopy.

The lever conveniently is forced downwardly by means of a helical spring 19 surrounding the upper end of the pin 18 and compressed between the. lever and a washer and nut on the upper end of the pin. With such an arrangement a tight connection is assured between the lower end of the pipe 62 and the plug 6I.

Also secured to the pipe 62 by means of the clips 1I is an electrical lead 8| to permit connection of 'the pipe in an electrical circuit for heating purposes, as will be described more fully hereinafter.

The plate 66 secured on top of the canopy also has an opening into the annular space surrounding the pipe 62 within the canopy and ram of the press. Secured in this opening is apipe 82 which is connected to a vacuum pump, not'shown. By means of this connection 62 the annular space within the canopy and ram around the pipe 62 may be evacuated.

Above the point where the clips 1l are attached the pipe 62 is bent from the vertical so that it illustrative embodiment, the pipe is to be heated electrically to insure free passage of molten metal therethrough from the container 81 to the press cylinder, the pipe desirably is covered throughout its length between the press and the container1 with a thick wall 83 of heat insulating material.

Secured to the pipe 62 over the upper end of the melting pot, as by means of a clip it, is an electrical lead 85. Over the melting pot the pipe 62 is bent downwardly and passes through a stumng box 3B in the upper end of the melting pot t1 into the pot. Conveniently this stung box 8S may be simiLr to the stufng box surrounding the pipe 62 where it emerges from the press canopy.

The pipe 62 desirably is one unbroken length extending from the point where it discharges into the press cylinder to the point where it is supplied with molten metal in the container 81. Where a single length of pipe is used there is much less danger of a leak permitting access of air to the molten metal in its passage through the pipe. Also there is less danger of the pipe becoming clogged, since uniform heating of the pipe is facilitated and Acan be more accurately controlled than would be the case if several lengths of pipe were used with elbows and couplings.' It is necessary that the pipe 52 be heated above the melting point of the metal which is to be extruded so that in passing from the melting pot to the press the metal will not freeze and block the pipe.

It will be noted that a portion of 'the pipe is surrounded by the press ram and canopy, that another portion of the pipe is exposed to the atmosphere except for the insulation 83, and that a third portion of the pipe extends into the cen'- tainer of molten metal. These several sections of the pipe will need different amounts of heat to furnish a substantially uniform temperature throughout the length of the pipe. Conveniently, thev pipe is heated by passing electric current longitudinally therethrough, and suitable connections are shown diagrammatically in Fig. 1.

In this illustrative embodiment the pipe is divided electrically into three sections. A source of electric current, for example a transformer 9|, is connected by means of an electrical conductor 92 to the frame of the lead press, and-by means of a conductor 93 to the electrical lead 8l secured to the pipe 62 adjacent the point where it emerges from the press canopy. A second source of electric power, for example the transformer 94, is connected by means of a conductor 95 tothe electrical lead 8| on the pipe 62, and by means of a conductor 96 to the electrical lead 85 on the pipe 62. A third source of electrical power,A for cxample the transformer 91, is connected by means of a conductor 98 to the electrical lead 815 on the pipe 62, and by means of a conductor 99 to the metal melting pot 81. By regulating the currents flowing through each of these three sections of pipe it is possible to obtain a substantially uniform temperature throughout the length of the pipe.

One means for segregating a charge of molten metal in the pot 81 and for forcing this molten metal through the pipe 62 into the press cylinder ls shown in section in Fig. 6. The pipe B2, passing downwardly through the stuing box 86 in the melting pot 81 terminates within the interiorly shouldered pipe with a close sliding t. VThe pipe |0| is secured at its lower end in the pump cylinder head |02. The pipe |0| connects by means of a passage |03 through the cylinder head with the interior of the pump cylinder |04.

The interior of the pump cylinder |06 also is connected through the passageway in thecylinder head, and the Valve |06 to the interior of the melting pot 91. The valve 05 is opened and closed by means of the valve stem |01 extending upwardly through a stui'ng box |08 in the top of the melting pot 3l.I The Valve 90S has a horizontal opening therethrough, so that when the valve is turned to one position this opening registers with the passageway |05, and when the Valve is rotated 90 degrees this opening in the valve is crossways of the passageway |05, preventing ow of metal therethrough. The valve operating mechanism will be described more fully hereinafter.

The pump cylinder head |02 desirably is positioned within the melting pot 81 so that in the normal course of operation molten metal always will be withdrawn from a point at some distance from the walls of the pot 81 as well as at some distance below the level of the metal. The level of metal in the pot will vary, of course, as molten metal is withdrawn and as new metal is added. Desirably the intake which supplies metal through the pipe 62 to the press is located far enough down in the pot so that any dross formed on the metal surface will not be carried through the pipe t2 into the press. Desirably, the intake for the molten metal is located some slight distance above the bottom and spaced from the Walls of the p ot to prevent transfer to the press of any impurities which may have accumulated or formed on the /bottom or walls ofthe pot. Y

Mounted within the pump cylinder IM is the piston |09, desirably fitted with piston rings H0.

Adjacent its upper end the cylinder |06 is provided with a plurality of ports to permit entrance and exit of metal back of the piston as the piston moves up and down in the pump cylinder. The cylinder conveniently is secured at `its upper end to the top of the pot 81, for example by means of a cylindrical member ll2'rmly secured in an opening in the top of the'pot.

Extending upwardly from the piston |09 to which it is secured is the piston rod 3. The piston rod ||3 passes through the cylinder Mld, a stung box H4 in the lower end of the member I2, and continues upwardly beyond the top of the melting pot. Formed on or secured to the upper end of the piston rod ||3 is a gear rack H5. The piston andpiston rod are movable vertically, and this movement is controlled by means of a pinion I6 engaging the rack I |5.

The pinion H6 is rigidly secured on the shaft I1. One end of the shaft I1 is rotatably mounted in bearings on the upper end of a housing ||8 rising from the top of the melting pot 81. Referring now to Fig. l, the other end of the shaft is rotatably mounted in a bearing, not shown, on the press canopy 22. Rigidly secured on the shaft ||1 adjacent the lead press is a sprocket ||9. Engaging the sprocket ||9 is a power transmission chain which passes downwardly and around a sprocket |2| rotatably mounted near the bottom of the columns 2|.

The ends of the sprocket chain passing around the sprockets I9 and |20 are connected by means of a screwthreaded link |22. Spaced apart on the link |22 are two sets of adjustable lock nuts |23 and |24. Engaging the link |22 between the two sets of lock nuts is the forked end of a bracket which is secured on the upper end of the hydraulic press plunger 3| so as to move up and down with the plunger.

It will be apparent that as the plunger 3| moves4 up and down the bracket |25 will cause the sprocket vchain |20 to move, thereby rotating the shaft ||1. As the press cylinder 24 is moved upwardly during an extrusion operation the shaft ||1 will be rotated so as to raise the piston |09, thereby filling the pump cylinder- |04 with molten metal from the melting pot. When the press cylinder 24 reverses direction and moves down' Wardly, the piston |09 will move in the opposite direction to force the molten metal from the pump cylinder |04 through the pipe62 into the press cylinder 24.

By spacing the sets of lock nuts |23 and |24 apart on the connecting link |22, a slight lost motion may be introduced so that molten metal is not forced from the pump into the press cylinder until the valve in the lower end of the press ram is fully opened. 'lhis lost motion also makes it possible to vmaintain any desired clearance, for example an inch, between the end of the ram and the surface of the molten metal during the charging operation.

One suitable mechanism for operating the valve |06 controlling the flow of molten metal into the pump cylinder |04 is shown in Figs. 6, 'I and 8. On the outer end of the shaft i l1, spaced a short distance apart, are rigidly secured two ratchet wheels |3| and |32. Mounted on the shaft i |1 hetween these ratchet wheels and free to turn about the shaft is a lever |33 having at its outer end a weight |34. Rotation of the lever |33 about the shaft ||1 is limited by means of the ears |35 and |36, which engage a stop |31 in the top of the housing I8 as the lever turns to the right or left as viewed in Figs. 7 and 8.

Pivotally secured on opposite sides of the lever |33 are the pawls |30 and |39 which engage, respectively, the ratchet wheels i3| and |30. Referring to Fig. 8, rotation of the shaft iii to the right when the lever |33 isfturned to the left, as shown in dotted lines, causes the ratchet wheel |3 I, engaging the pawl |38 to turn the lever to the right. When the lever is carried past the vertical position the weight |34 on its outer end causes the lever to continue its turning movement to the right at a more rapid rate until the ear 36 engages the stop |31. vDuring this more rapid turning movement the pawl |3615 lifted out of enu gagement with the paw] wheel |39 and is held out of engagement by the arm |00 xed on the top of the housing i l0 which engages the outer end of the pawl.

' is held out of engagement by means of the arm |4| secured on the top of the housing H0.

4Thus it will be seen that rotation *of the shaft. 'I I1 in either direction approximately one eighth of a turn shifts the lever |33 from one limit of its range of movement to the other limit.

Also mounted on the shaft ||1 adjacent its end is a sheave |42 which is secured to the lever |33 by means of the connection |43 so that the sheave will turn about the shaft ||1 with the lever |33. Passing around the sheave |42 is lthe wire or cable |44. The wire |44 passes downwardly, changes directionA about the sheave |45 rotatably mounted on the housing ||0. and then around the sheave |46 rigidly secured on the upper end of the valve stem |01. The valve stem. |01 is pressed downwardly to force the valve |06 into its seat as by means of a helical spring |41 surrounding the valve stem |01 and compressed between ther valve stem bearing |48 and a collar |49 secured on the valve stem |01.

From the foregoing description it will be apparent that upon rotation of the shaft ||1 approxiy. mately one-eighth of a turnin one direction the valve |06 will be opened, and that upon rotation ofthe shaft ||1 approximately one-eighth of a turn in the opposite direction the valve |06 will be closed. During the extrusion operation the valve |00is open so that molten metal will be drawn into the pump cylinder |04 by means of the piston |09, and as the press cylinder moves away from the press ram the valve |06 is closed so that the molten metal segregated in the pump cylinder is forced by the piston through the pipe Desirably the diameter of the pump cylinder and the stroke of the pump piston are such that as metal is being extruded from the press an equivalent quantity of molten metal is being segregated within the pump cylinder. For example, the pump cylinder might have the same internal diameter as the press cylinder, and the pump piston might move through the same distance and at the same speed as the press cylinder. Under such conditions the pump always would contain the correctv amount of molten metal for recharging the press, regardless of the amount oi metal whichmay have been extruded from the press.

During the extruding operation a specic quan tity of molten metal equivalent to the quantity of metal extruded is being segregated within a separate container, in this instance the pump. When the extrusion operation has been completed the press cylinder recedes from the press ram, and as it does so, the press cylinder is progressively charged with this metal which has been segregated in the separate container. By suitable adjustment of the lost motion connection between the press cylinder and the transmission chain which actuates the metal pump the ow o molten metal into the press may be delayed to maintain a clearance between the level of the A62 into the press cylinder. f

metal and the end of the ram. When the chargn ing of the press cylinder has 4been completed and the metal has cooled suiilciently to permit ex-n trusion thereof the pump. in the melting pot segregates the metal which will be required for the next charging of the press. This operation of the pump is fully automatic in response to relative movement between the -press vcylinder' and ram. Desirably the space within the press cylinder under the stuiling box around the ram is evacuated, throughout the operation, and air or other gases do not have access to the metal at any time during the charging operation.

Splashing of the metal and the formation oi' irregular lumps in the press cylinder during the charging operation are greatly reduced by rn of the point and direction of discharge of the molten metal into the cylinder, as well as by reason oi' the fact that the molten metal falls through a much shorter distance in the cylinder. Since the cylinder is evacuated, the formation of gas bubbles or pockets is eliminated.

Ifthe distance which the molten metal must rise in passingfrom the melting pot through the 'pipe 6 2 to the press cylinder u not. too great.

the atmospheric pressure maybe utilized to force molten metal from the melting pot into the evacuated press cylinder. In that case the pump disclosed in Fig. 6 and the operating mechanism therefor disclosed in Figs. 6, 7 and 8 may be omitted, and a valved inlet alone is required for the end of the pipe 62 within the container 67.

Such a valved inlet is shown in Fig. 9. Anr

opening in the top of the melting pot 87 is closed with a plate |5|, conveniently held in' place by means of screws |52. An aperture |53 -in the plate |5| provides an entry-way for the 'valve stem, and surrounding this opening and depending from the plate is the tube ld. Conveniently the tube |54 may be secured to the plate |5| by welding. Closing the lower end of the tube |56 is the valved inlet member |55 which may be held in place by means of screws |56. This valved inlet member |55 desirably is positioned within the melting pot so that metal will be withdrawn from a point spaced from the Walls of the Vcontainer and below any dross which may form on the top of the metal.

The valve stem |59 extends upwardly through the tube |56 beyond the top of the melting pot. and conveniently may be rotated manually to open and close the valve. When the valve is open molten metal may pass through the ports |57, the passageway |56 in the member |55, and the pipe |60 into the tube d. Conveniently the pipe |66 is interiorly shouldered, and the end oi the pipe 62 slides into the pipe |66 against this shoulder. The pipe 62 passes upwardly through a stulng box |63 in the plate |5l, and thence to the extrusion press in the manner shown in Fig. l.

During the extrusion operation the valve in the lower end of the press ram is closed, and the valve |58 in the melting pot also is closed.` As the press cylinder moves away from the ram after the charge in the press cylinder has been extruded, the valve |56 is opened. As hereinbefore described the press cylinder is evacuated throughout this operation, as by means of the pipe connection 38, and when the valve |56 is opened molten metal is forced by the atmospherlc pressure from the melting pot through the pipe 62 into the press cylinder.

In extrusion presses Where it is not possible to see the level of lmetal inthe press cylinder during a charging operation, as for example where the arrangement shown in Fig. 9 is used for controlling the flow of molten metal into the press cylinder, it is desirable to have a continuously operating indicator to indicate the amount of metal extruded from the press during an extrusion operation, and also the amount of molten metal supplied to the press during a charg-` ing operation.

The windlass il@ is mounted so as to turn freely about Aa stud |76 secured at one end in the support |77.

Secured to the support |77, as at |76, and in front of the windlass |`||l is a dial |79. This dial is shown in front elevation in Fig. 11. The hub of the windlass i7@ Aprojects through the central opening in the dial |79 and has secured thereto the hand |80. It will be apparent that asthe press cylinder moves up or down the eX- tent of this movement will be indicated on the dial |79 by means of the hand |80.

Within the melting pot is a iloat |8| which moves up and down as the level of molten metal in the pot varies. Conveniently this float may be guided in its movement by the vertically extending arm passing upwardly through the top oi the melting pot and engaging the guides |82 and |63 fastened to the melting pot.

Secured tol the float guide,` as at |85, is one end of a wire or cable |86. The wire |36 passes upwardly, changes direction around the sheaves |87 and |88, and then passes downwardly and is -secured at its end to one end of a gear rack |89. Fastened to the lower end of the'gear rack is a counterweight |95. Engaging the rack |86 is a pinion |96, rigidly secured on one end of the shaft |||I passing vthrough the stud |76 to the face of the dial |79.

Secured to the end of the shaft itl adjacent the dial face is a hand |62. Desirably this hand is secured to the shaft ,HQI so that normally it will turn with the shaft, but so that it may readily be adjusted relative to the shaft. Such a connection may comprise the screw |93 in the end of the shaft, and a helical spring |6| compressed between the head of the screw and the hand |92. It will be apparent from the foregoing description that any variation in the level of the molten metal in the melting pot will be indicated on the dial face by means of the hand Deslrably the scale on the dial |76 and the diameter of the windlass |74 are chosen so that the hand |66 records directly the vertical movement of the press cylinder in inches. The diameter of the pinion |96 desirably is chosen so that the drop in the level of molten metal in the melting pot while the cylinder is being charged with molten metal will be indicated by/ the hand |92 directly in terms of the number of inches which the level of metal in the press cylinder is raised. With this arrangement the amount of metal extruded during an extrusion operation is continuously indicated, as is also the amount of metal added to the press during a charging operation.

The time required for recharging the press may be reduced by permitting molten metal to enter the press as the press cylinder recedes from the ram. During this operation a clearance, usuallyabout one inch in lead presses, desirably is maintained between the end of the ram and the level of the molten metal, and this clearance may be accurately and conveniently controlled with the mechanism described.

For example, when the press cylinder has reached the top of its stroke, that is at the end of the extrusion operation, 'the hand |92 is set one inch ahead oi the hand |80, for example as shown in Fig. 1l. When the press cylinderrecedes one inch, the valve in the melting pot being closed, the hand |60 has been moved until it is directly under the hand |92. At this point the inlt valve within the melting pot is opened to permit molten metal to flow through the pipe 62 into the press cylinder. The amount by which this valve is opened is adjusted so that as the hand |80 continues to move around the dial, the hand |92 is' kept directly over the hand |80. With this arrangement the'molten metal will follow up the receding ram in the press cylinder and maintain the desired clearance between the end of the ram and the molten metal.

Applicant has provided improved apparatus whereby metal sheaths may be extruded about electrical cables, and in which oxidation of the metal during the extruding operation is prevented. Splashing of the metal and formation of gas pockets in the charge are greatly reduced. Furthermore, introduction of impurities into the metal during the press charging operation is prevented, and the time required between extruding operations for charging the press is substantially shortened. This economyin time is made possible by progressively charging the press cylinder with molten metal as the cylinder and ram separate, and also by accurately controlling the temperature of the molten metal as it enters the cylinder.

It will be understood that the present invention may be variously modified and embodied within the scope of the subjoined claims.

I claim:

1. In apparatus for 4extruding solidified metal the combination of a cylinder, a die block connected to one end of said cylinder, said die block -having a transverse die opening therein, a ram air into the cylinder around the ram while per-y mitting relative movement therebetween, means for charging the cylinder with molten metal through the longitudinal opening in the ram, and means for causing relative movement between the cylinder and the ram to extrude the metal from the cylinder after it has solidied.

2. In apparatus for extruding solidified metal the combination of a cylinder, a die block connected to one end of said cylinder, said die block having a transverse die opening therein, a ram having an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, sealing means betweenV the cylinder and the ram preventing the entrance of air into the cylinder around the ram while permitting relative movement therebetween, means for charging the cylinder with molten metal through the longitudinal opening in the ram, means for causing relative movement between the cylinder and the ram to extrude the metal from the ycylinder after it has solidied, and a valve mounted in the inner end of said ram preventing ow of molten metal outwardly from the cylinder through the longitudinal opening I in the ram.

means for causing relative movement between the cylinder and the ram to extrude the metal from the cylinder after it has solidified, a valve in said openingadjacent the lower end of the ram, and means which, during the course of normal operation, causes said valve to open automatically in response to movement of the cylinder relative to the ram in one direction and to close automatically in response to movement of the cylinder relative to the ram in the opposite direction.

4. In apparatus for extruding solidified metal the combination of a cylinder, a die block connected to one end of said cylinder, said die block having a transverse die opening therein, a ram having an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, means for causing relative movement between the cylinder and the ram, sealing means between the cylinder and theram preventing the entrance of air into the cylinder around the ram while permitting relative movethe combination of a cylinder, a die block conl nected to one end oi said cylinder, said die block having a transverse die opening therein, a ram having an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, means for causing relative movement between the cylinder and the ram,

sealing means between the cylinder and the ram preventing the entrance of air into the cylinder around the ram while permitting relative movement therebetween? means for progressively charging the cylinder with molten metal through the longitudinal opening in the ram as the ram moves outwardly relative to the cylinder, and.

means which in the normal course of operation \controls the ow of molten metal into the cylinder automatically in response to relative movement between the cylinder and the ram.

6. In apparatus for extrudingsolidied metal the combination of a cylinder, a die block ccnnected to one end of said cylinder, a ram hav- ,f

ing an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, sealing means between the cylinder and the ram preventing the entrance of air into the cylinder around the ram while permitting relative movement therebetween, means for charging the cylinder with molten metal through the longitudinal opening in the ram, means for causing relative movement between the cylinder and the ram to extrude the metal from the cylinder after it has solidied, means for measuring and indicating continuously the amount of metal extruded during an extrusion operation, and meansv for measuring and indicating'continuously the amount of metal which enters the cylinder during a charging operation.

'1. In apparatus for extrudlng solidified metal the combination of a cylinder, a die block connected to one end of said cylinder, a ram having an opening extending longitudinally therethrough. said ram extending `into the other end of said cylinder, sealing means between the cylinder and the ram preventing the entrance of air into the cylinder around the ram While permitting .relative movement therebetween, a container for molten metal, means for charging the cylinder with molten metal from said container through the longitudinal opening in the ram, means for causing relative movement between the cylinder and the ram to extrude the metal from the cylinder after it has solidified, and means operating automatically and continuously in response to extrusion of metal from the cylinder for measuring od and segregrating an equivalent charge of molten metal for the cylinder.

8. in a metal extruding apparatus the combination of a cylinder, a die block connected to one end or" said cylinder, a ram having an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, sealing means between the cylinder and the ram preventing the entrance of air into the cylinder around the ram while permitting relative movement therebetween, a container for molten metal, means for charging the cylinder with molten metal from said container through the longitudinal opening in the ram, means for causing relative movement between the cylinder and the ram to extrude metal from the cylinder, means operating automatically in response to relative movement between the cylinder and the ram duringextrusion of metal from the cylinder for measuring o and segregating in said container an equivalent charge of molten metal for the cylinder and operating automatically in response to relative movement between the cylinder and the ram in the direction opposite to that for extruding metal for delivering said charge of molten metal to the cylinder.

19. In apparatus for extruding solidied metal the combination of a cylinder, a. die block lconnected to one end of said cylinder, a ram extending into the other end of said cylinder, means for charging the cylinder with moltenv metal, means for causingv relative movement between the cylinder and the ram to ex'trude the metal from the cylinder after it has solidied, means for measuring and indicating continuously the amount of metalextruded during an extrusion operation, and means for measuring and indicating continuously the amount of metal which enters the cylinder during a charging operation.

10. In a metal extruding apparatus the combination of a cylinder, a die block connected to one end of said cylinder, a ram extending into the other end of said cylinder, a container for molten metal, means for charging the cylinder with molten metal from said container, means for causing relative movement between the cylinder and the ram to extrude metal from the cylinder, and means operating automatically in response to relative movement between the cylinder and the ram during the extrusion of metal from the cylinder for measuring oil and segregating an equivalent charge of molten metal for the cylinder.

11. In a metal extruding apparatus the combination of a cylinder, a die block connected to one end of said cylinder, a ram extending into the other end of said cylinder, a container for molten metal, means for charging the cylinder with molten metal from said container, means for causing relative movement between the cylinder and the ram to extrude metal from the cylinder, means operating automatically in response to relative movement between the cylinder and the ram during extrusion of metal from the cylinder for measuring o and segregating in said container an equivalent charge of molten metal for the cylinder and operating automatically in response to relative movement between the cylinder and the ram in the direction opposite to that for extruding metal for delivering said charge of molten metal to the cylinder.

12. In apparatus for extruding solidified metal the combination of a cylinder, a die block connected to one end of said cylinder, a tarn extending into the other end of said cylinder, sealing means between the cylinder and the ram preventing the entrance of air into the cylinder around the ram while permitting relative movement therebetween, means for charging the cylinder with molten metal through a longitudinal opening in the ram, means for causing relative movement between the cylinder and the ram to extrudethe metal from the cylinder after it has solidified, and means for evacuating the space between the cylinder and the ram under the said sealing means.

13. In apparatus for extruding solidied metal the combination of a cylinder, a die block connected to one end of said cylinder, a ram extending into the other end of said cylinder, sealing means between the cylinder andthe ram preventing the .entrance of air into the cylinder around the ram while permitting relative movement therebetween, means for causing relative movement between the cylinder and the ram to extrude the metal from the cylinder after it has solidied, and means for measuring and indicating continuously the amount of metal extruded vfrom the cylinder during an extrusion operation.

14. In apparatus for extruding solidified metal the combination of a cylinder, a die block conlil nected to one end of said cylinder, a ram havingbination of a cylinder, a die block connected to one end of said cylinder, a ram having an opening extending longitudinally therethrough, said ram extending into'the other end of said cylinder, means for causing relativemovement between the cylinder and the ram, means for charging the cylinder with molten metal through the longitudinal opening in the ram, said means comprising a metal pipe smaller than the longitudinal opening through the ram extending from the inner end of the ram outwardly through the longitudinal opening therein, and means for evacuating the space in said opening exteriorly of said pipe.

16. In a metal extruding apparatus the combination of la cylinder, a die block connected to one end of said cylinder, a. ram having an opening extending longitudinally therethrough, said ram extending into the other end of said cylinder, means for causing relative movement between the cylinder and the ram, means for charging the cylinder with molten metal through the longitudinal opening in the ram, said means comprising a metal pipe extending from the inner end of the ram outwardly through the longitudinal opening therein, and means for heating said pipe electrically throughout its length.

17. In a metal extruding apparatus the combination of a cylinder, a die block connected to one end of said cylinder, a ram havingan opening extending longitudinally therethrough,v said ram extending into the other end of said cylinder,

means for causing relative movement between the cylinder and the ram', means for charging the cylinder with molteny metal through the longitudinal opening in the ram, said means com. prising axnetal pipe extending from the inner end of the ram outwardly through' the longitudinal opening therein, and an electrical connection between the pipe and the ram adjacent the inner end of the ram, said pipe and ram being otherwise insulated electrically one from the other.

18. The combination with a press for extruding a metal sheath on an electrical cable, said press comprising a cylinder, a die block connected to one end of said cylinder, a ram having an opening longitudinally therethrough extending into the other end of the cylinder, and means for causing relative movement between the cylinder l and the ram, of a container for the molten metal with which the press is to becharged, and means for charging the press With'molten metal from the container, said means comprising a continuous one-piece pipe extending from a point, in the container below the level of the metal and spaced from the walls of the container through the longitudinal opening in the ram to a point Y where it discharges directly into the press cylinder.

19. The combination with a press for extruding solidified metal, said press comprising a cylinder, a die block connected to one end of said gitudinal opening in the ram to a point where it discharges directly into the press, and means for passing an electric current longitudinally through the pipe to maintain the pipe temperature sufflciently high to prevent the molten metal from congealing while flowing through the pipe.

20. The combination with a press for extruding solidiiled metal of acontainer for the molten metal with which the press is to be charged, and means operating automatically and continuously in response to extrusion o'f metal from the press to segregate an equivalent quantity of molten metal in the container.

2l. The method of operating apparatus for extruding metal sheaths on electrical cables, said apparatus comprising a cylinder, die block and ram, which method comprises electing relative withdrawal movement between the cylinder and the ram to permit charging of the cylinder with molten metal, discontinuing such movement while the cylinder still engages the end of the ram, charging the cylinder with molten metal free from gas and other impurities, permitting the molten metal to cool and solidify,` applying suction to the top of the metal in the cylinder to remove from the cylinder during the charging and cooling operations any gas which may have been entrained in the molten metal, and effecting relative movement between the cylinder and the ram to extrude the solidified metal through the die block.

22. 'I'he method of charging the cylinder of a press for extruding metal sheaths on electrical cables with molten metal from a molten metal container, which method comprises withdrawing molten metal from the container at a point below the dross line and spaced from the walls of the container, conveying the" metal so withdrawn to the press and charging the press cylinder therewith, preventing access of air to the molten metal in its passage from the container to the press cylinder, and applying suction around the ram and in the upper portion of the cylinder to remove from the cylinder during the charging operation any gas which may have been entrained in the'molten metal.

EDGAR, W. MAcKNIGHT.