US2674373A - Metal extrusion press - Google Patents

Description

April 6, 1954 A. LATIN METAL ExTRusIoN PRESS 5 shetssheet 1 Filed July 2, 1951 Inventor Aub/"ey L atm By i M Attorneys April 6, 1954 A. LAT, 2,674,373

METAL EXTRUSION PRESS Filed July 2, 1951 5 Sheets-Sheet 2 F G. 2. ,2 l [f4 il 40 /f/ A ttorney April 6, 1954 A LATlN 2,674,373

METAL ExTRUsIoN PRESS Filed July 2, 1951 5 Sheets-Sheet 3 Inventor u/brej/ Lai/h ttornys n Inventor l Aub/"ey Lczzm Attorneyg 5 Sheets-Sheet 4 A. LATIN METAL EXTRUSION PRESS April s, 1954 Filed July 2, 1951 (O (D l Filed July 2 1951 April 6, 1954 A. LATlN 2,674,373 METAL ExTRUsIoN PRESS 5 Sheets-Sheet 5 f Inventor ttorney s Patented pr. 6, "1954 METAL EXTRUSION PRESS Aubrey Latin, London, ish Insulated Gallen England, assigner to Britders Cables Limited, London, England, a British company Application J uly 2, 1951, Serial No. 234,765

Claims priority, application Great Britain July 5, 1950 7 Claims.

This invention relates to extrusion presses for metals, for instance, aluminium and aluminium alloys, in which the metal to be extruded is put into the extrusion cylinder or container in the form or" a heated billet or billets shaped to iit the cylinder, which may, or may not, contain a central mandrel. A ram working from the rear end of the container forces out the metal through a die or between inner and outer dies in the front end of the container.

An object of the invention is to secure good union between the metal of successive billets and thereby permit of extrusion taking place in great lengths without the formation of defective parts where two billets come together and intermingle.

The irregularities of the metal which lead to `the production of defects are largely found in the outer cylindrical surface of the billet and the directly adjacent region, being due both to surface contamination and to local temperature diierence, accompanied by other physical diierences.

The flow of metal through the press is also frequently such as -to lead to the collection of what may be termed dead metal near the outer walls, particularly near the front end of the press, and there is also frequently an accumulation of defective material at or adjacent to this region of dead metal. There is also a tendency for defective material to flow towards the central part of the rear end of the billet. It is an object of this invention to elTect a removal of some or all of the defective material and to improve the ow characteristics of the metal being extruded.

The invention provides for the diversion of some portion of the billet from the outer or some other part of it as discarded metal which does not pass -to the die or dies. Ports placed near the extrusion end of the extrusion cylinder or container in the wall thereof provide for this diversion, the ports being placed and shaped appropriately to secure the passage out of the container of the metal to be discarded. The container wall, at, or adjacent to these ports, may have an inward step to produce a part near the extrusion end of smaller cross-section than the main body of the container. The ports then are placed just before or at this step and may be parallel with the axis of the container or may be inclined outwards.

The diversion ports may be so dimensioned and shaped that relative to the main course of the metal resistance to outflow is such as to divert the desired portion of the billet section, for instance, from 5-25% according to the conditions oi the case. Since the pressure required to extrude the metal through these diversion ports may be less than that required for the extrusion of the product itself, it is arranged that the rejection of the unwanted metal should take place only at intervals, for instance at the beginning and/or end of the extrusion stroke for it is at the beginning and end of the extrusion stroke that defects are likely to occur and the maximum benet obtained by the diversion and rejection of the unwanted metal. This is accomplished by provision of means for opening and closing such ports as and when required. Such means may, for example, comprise a movable shutter or shutters which are slidable across the face of the ported wall of the container to close the ports as and when required, shearing off the rejected metal as they do so.

The invention will now be more fully described with the aid of the accompanying diagrammatic drawings wherein- Figure l shows partly in elevation and partly in section an example of an aluminium billet press of which the extrusion cylinder is provided with diversion ports in accordance with the invention,

Figure 2 is a fragmental section drawn to a larger scale than Figure 1 and showing the diversion ports and their closure means more clearly,

Figure 3 is a section taken in Figure l,

Figure 4 is a fragmental section drawn to a larger scale than Figure 1 and showing an example of an extrusion press constructed in accordance with the invention and suitable for applying an aluminium sheath to a cable core,

Figure 5 is a fragmental section on the line V-V of Figure 4,

Figure 6 is a View partly in elevation and partly in longitudinal section of a further example of a billet press provided with ports in accordance with the invention, and

Figure 7 is a cross-section taken on the line VII-VII in Figure I6.

A description will rst be given of the press shown in Figures 1-3 of the drawings. As Will be seen it is a vertical press comprising an extrusion cylinder or container l for receiving a billet 2 which is ejected through a die 3 by means of a ram 4. The press is of the type in which the container is mounted on a table 5 secured to the ram 6 of a hydraulic cylinder 'i and the exon the line Ill- III trusion ram 4 is rigidly supported above the container I by a cross-head 8 mounted above and secured to the hydraulic cylinder 'I by pillars 9, which in this case are four in number. The container I is built up of inner and outer liners I and II housed in an outer shell I2. The shell I2 is secured to the table 5 by bolts I3 and the outer liner I2 is fitted with tubular electric heaters I4 by means of which the container may be maintained at a suitable extrusion temperature.

having a throated aperture I8 and an upper part .i

I9 having a central dependent projection 28 of which the lower end enters the throat I8 and co-operates with it to dene an annular extrusion orifice. Around the dependent projection is an inverted annular channel 2| co-operating with the upper end 22 of the throated aperture in the lower part i1 to form an annular chamber leading to the extrusion orice and into which metal is forced through three feed ports 23.

The upper part of the die holder forms a continuation of the liner` I8 but its bore is less than that of the liner I6 so as to form a step 24 in the wall of the extrusion cylinder or container. In this step, in accordance with our invention, there is provided a ring of holes 25 which extend through the die block, preferably in directions parallel to the axis of the block, as shown. These holes 25 may be so dimensioned and their number be such that collectively they allow a desired proportion of the billet, for instance from 5 to 25%, to pass through them to carry away the defective meta-l from the peripheral part of the billet. In such case the bolster I6 holding the die holder in place will be correspondingly apertured as shown at 26 to allow the ejected metal to escape, the holes 25 in the bolster preferably being of greater diameter than the rejection ports 25. I prefer however to make the ports 25 larger than is required to divert from 5 to 25 of the billet from being extruded through the annular die orice and to a-rrange that rejection of unwanted metal takes place only at the beginning and/or end of the extrusion stroke by arranging for the bolster i6 to be capable of a rotary movement sufficient to open and close the diversion ports 25, and. thus to serve as shear blades capable of shearing off the discarded lengths of metal as the bolster moves from its opento its closed position. Naturally this places a limitation upon the number or size of the ports 25 since each must then be spaced circumferentially from the adjoining ports by a distance greater than the port diameter.

As will be seen from Figures 2 and 3 I provide in this particular example of press ten diversion ports of which the collective cross-sectional area approximates to 12% of the cross-sectional area ofthe container bore but naturally more holes of smaller diameter may be provided or fewer holes of somewhat larger diameter. The collective area required is not critical when the quantity of rejected metal can be controlled by varying the time during which the ports are open. To facilitate entry of defective meta-l into the ports they are located in an annular channel in the radially outer part of the annular step 24, Between each two neighbouring ports 25 in the channel, the channel depth increases from a minimum midway between the ports to a maximum at the edges of the ports.

The bolster I6 is given a limited angular movement in its housing in the surface of the table 5 by means of a worm 21 cut in a shaft 28 journalled in the table 5 and carrying a. hand wheel 29. The worm 2l engages a worm wheel segment 30 cut in the periphery of the bolster. Normally this bolster is tightly clamped between the container I and the table 5 in order to form a satisfactory shutter for the ports 25. It is released by means of the ram 3l of a hydraulic cylinder 32 housed beneath it in the table 5. This ram carries a group of thrust pins 33 which freely pass through arcuate slots 34 in the bolster I6 and engage the underside of the container I. By applying sufficient pressure to the ram to cause the bolts I3 to stretch elastically to a slight extent, the bolster IB is temporarily released and is able to be rotated by applying a power drive to the worm sha-ft 28 or by turning the hand wheel 29.

The tubing extruded through the die 3 passes vertically downwards and round a guide pulley 35 and out through an opening 36 in the wall of the pillar 3'! supporting the table 5.

The press shown in Figures 1 3 is suitable for the production of coreless tubing. To enable it to sheath a cable core modifications are necessary. These are shown in Figures 4 and 5 from which it will be seen that a mandrel or core tube 4| is provided for leading the core to the inner extrusion die or point 42. The wall of the mandrel may be cavitied to allow of the circulation of a coolant. The mandrel 4I and the inner die or point 42, may be supported by the upper part of the die holder or, as shown by a perforated plate or spider 43 interposed between the inner liner I0 and the die holder I5. In place of the solid ram 4, shown in Figure 1, a tubular ram 44 is used for operating on billets of corresponding form. Apart from these diiferences the press resembles that shown in Figures 1-3, and similar parts have been given the same reference numerals. The passages 45 in the spider 43 are uniformly distributed around the core tube 4I and the point- 42 and lead to the ports 25 and tothe annular forming chamber 46 in the die holder. As will be seen from Figure 5 the passages 45 and ports 25 are circumferentially aligned. This is the preferred arrangement. If they `arefnot so aligned it is desirable to provide an annular channel 41 in the upper face of the die holder to lead metal from the passages 45 to the ports 25 when the-bolster I6 is set in the rejection position.

In the horizontal aluminium billet press shown in Figures 6 and '7 the container 5I resembles the container I shown in Figures 1 3, in that it comprises a liner 52 and a stepped die holder 53 housed within lan outer liner 54 which is itself housed in a container vbody 55. In this case, however, the container body, filled with heaters 55a, is mounted in a holder 55h in a known manner which allows for radial expansion of the body. The holder is supported by beingy threaded on four horizontal tie rods 56 connecting the main crosshead 5'I to a hydraulic cylinder 56 in which works the ram 59 which operates the movable crosshead 60 which slides on the tie rods 56 between the collars 6l and 62 and carries the extrusion ram 63. The die 64 and its holder 53 are of the same form aslthose shown in Figures 1-3 and need no further description. They areV held in place and supported against the thrust of the extrusion ram by a bolster 65 which is recessed on its rear face to receive a boss 66 on the adjacent face of a slidable bolster support cross-head 6l. The head 66 forms a trunnion co-axial with the container, on which the bolster is rotatably supported. The bolster 65 and its support are urged towards the container body 55 by a slidable centrally apertured wedge 68 which co-operates with a fixed centrally apertured wedge 69 housed in the adjacent face of the main cross-head 51.

'I'he sliding wedge 6s is tightened and slackened by means of a, hydraulic ram 10 working in a cylinder 1I carried by a bridge 12 whose ends are anchored to the two upper tie rods 56. When the wedge is slaokened the bolster 65 is free to rotate through a limited angle suiicient to move it from a position in which the ports 12 in the die holder are closed by the bolster into a position f in which the through passages 'i3 in the bolster register with the ports. This movement is effected by a second ram 14 working in a cylinder 15 on a bracket 'I6 on the cross-head 6l and carrying at its free end a gudgeon pin 'Il working in slots I8 in two radially projecting brackets 'I9 on the periphery of the bolster 65.

It will be appreciated that a Wedge device of this kind may be used to hold up the bolster I6 of the press shown in Figures 1-3. in which case the hydraulic ram 3| and thrust pins 33 are dispensed with. It will also be understood that rotation of the bolster I6 may be effected by means of a hydraulic ram in the way described with reference to Figures 6 and 7 and that the bolster 65 shown in Figures 6 and 7 may be rotated by worm gear in the manner described with reference to Figures 1-3 instead of by a hydraulic ram, if required. In the examples of presses shown in the drawings the bolsters I6 and 65 serve both to hold up the die and as a shutter for closing the outlet ends of the diversion ports but it will be apparent that these functions may be performed by separate members if required.

It will be seen that in all the examples described there is a step in the Wall of the cylinder of the container where the liner meets the dieholder and that this stop causes an obstruction to the forward movement of the main body and produces an additional working of the metal before it reaches the die. It is believed that additional working of the metal in this region is advantageous. Naturally, the step also limits the stroke of the ram which is of a cross-section suitable for working in the main part of the cylinder, i. e. that constituted by the inner liner l0 or 52. It will be apparent from Figure 4, that in addition to the effect due to the step 4l, additional working will be caused to take place by the insertion of the perforated plate or spider serving to support a. central mandrel and that this plate or spider will further limit the stroke of the ram. In some cases it may be advantageous to obtain working of the metal by inserting a perforated plate or spider instead of by providing a step in the cylinder wall but a step is preferable as it provides an ideal location for the entrances to the diversion ports.

It will be apparent that the press shown in Figures 6 and 7 may be adapted for the sheathing of cable cores by replacing the die 64 by an outer die and fitting an oil or water cooled tubular mandrel carrying a tubular inner die, e. g. as shown in Figure 4. Naturally the extrusion ram and the main hydraulic ram must then be tubular and the latter carry a tubular tail which projects through the tail end of the cylinder 58.

In working in accordance with the improved method I prefer, as I have indicated, to limit the time during which metal is discarded through the diversion ports and to proceed as follows: After withdrawing the ram a hot billet is inserted and, the diversion ports being closed by the rotatable bolster, the ram is advanced and the metal of the billet is forced forward rst filling the ports and then extruding through the die orifice. Before the extrusion ram completed its stroke it is stopped, leaving about 20% of the billet in the container. The ram is then withdrawn, the bolster rotated to open the rejection ports and a fresh billet is inserted in the container and the ram re-inserted and advanced to expel through the ports the tail end part of the rst billet, in which part the greater portion of contaminated or defective metal from the first billet is to be found, and if required the nose end part of the fresh billet also. The ram is then withdrawn slightly to release the pressure on the metal, the bolster rotated to shear 2 through the rods of rejected metal and close the ports, after which the ram is advanced once more to extrude all or the remainder of the metal of the second billet except the tail end amounting to about 20%, whereupon the ram is withdrawn, the bolster rotated to open the ports and a new billet inserted and the cycle repeated. It will be understood that the gure of 20% is mentioned by way of example and that it may be found that it is unnecessary to discard such a high proportion of the billet as 20%.

To assist the process of transferring contami-v nated metal to the radially outer part of the cylinder where it can be expelled through the ports, the adjoining faces of the ram and the billet and those of old and new billets are arranged to be of such a form that contact is initially made in the central part of the two surfaces and the area of contact gradually enlarged so that any gas located between the surfaces can escape laterally. This may be done in either of two ways. The front end of the ram may be made concave as shown for example at 8l in Figure 1, in which case the tail end of each billet is made convex with a radius of curvature slightly less than that of the concave surface of the ram, as shown at 82. With a ram of this form the residue of metal in the cylinder will have been shaped by the ram so as to be convex. Accordingly the front end of each new billet should be at or concave with a larger radius of curvature than that of the residue. Alternatively the front end of the ram may be convex, as shown for example at 83 in Figure 4. In this case the tail end of each new billet has a radius of curvature greater than that of the face of the ram, and is preferably at but ythe front end should be made convex with a radius of curvature slightly less than the radius of curvature of the convex face of the ram.

What I claim as my invention is:

1. A billet press for extruding metal, comprising a container for receiving a billet of extrudable metal, an extrusion ram for forcing said metal from said container through an extrusion orifice, ports at the front end of said container for the escape from said container of extrudable metal containing defective material, and means for opening and closing said ports as and when required.

2. A billet press for extruding metal, comprising'a container fors receiving La'billet of extrud able' metal, an extrusion ram for forcing` said metal from said container through an` extrusion orice, ports at the front end of said container for the escape from said container ofext-rudable metal containing defective material, and a slidable shutter for closing each of saidports, said shutter serving as it closes -the port to shearA oi rejected metalescaping through the port.

3; Abillet press for extruding metal, comprising a container for receiving a billet of extrudable rmetal, an extrusion ram for forcing said metalfromfsaid container through an extrusion orice in the front end Wall of said container, a ring of ports for the escape of metal'containing defective material surrounding the extrusion orice, a bolster for supporting the front end Wall of said container, said 'bolster having a ring of apertures,. and means for rotating said bolster about the axis of said container from a position in which its apertures register with the outlet ends of said ports toa position in which it closes the outlet ends of said ports.

4. A billet press as claimed in claim 3, in which a holder for an extrusion die forms at least part of the front end wall of said container and said ports are located in said die holder.

5. A billet press for extruding metal, comprising. a container for receiving a billet of eX- trudable metal, an extrusion ram for forcing said metal from said container through an extrusion orifice in the front end wall of said container, a ,ring of ports for the escape of metal containing defective material surrounding the extrusion orice, a container support, a mult-aperf tured bolster between said container and said container support, bolts for clamping said bolster between said container and said container support, means for stretching said bolts elastically to release said bolster from the clamping action of said bolts, and means for rotating said bolster,

8 when released', about the 'axis of saidcontainer from a position in which apertures lin said bolster register with the-outlet ends of said ports tol a position in which it 'closes Vthe outlet ends`r of said ports.

6. A billet press -as speciiied in claimv 5, wherein said bolt-stretching means comprises'a hydraulic ram-and a plurality of thrust pins carri`ed on said lram and passing through slotsl in said bolster.'

7. A billet press for extruding metal, comprising acontainer'for receiving 'a'billet of vextrudable-metal, an extrusion ram for forcing said metal from said container through an extrusion orice` in the front end wall of said container, a ringof ports for the escape of metal containing defective material surrounding the extrusion orice, a container support, amulti-apertured bolster between said container and said container support, a centrally aperturedr wedge between said bolster and said container support for holding said bolster against the end Wall of said container, means forV tightening and loosening said wedge, and means for rotating said bolster, when released by looseningvsaid Wedge, about the axis of said container from a position in which apertures in said bolster register with the outlet ends of said ports to a position in which it closes the outlet ends -of said ports.-

References Cited in the file of this patent UNITEDv STATES PATENTS Number Name Date 327,835 Tatham Oct. 6, 1885 1,720,722 Dean July 16, 1929 FOREIGN PATENTS Number Country Date 271,378 Germany Feb. 8,1913 570,262 Germany Aug. 4, 1931

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