GB2175832A - Extrusion wheel member - Google Patents

Abstract

A rotary wheel member for use in a friction type, conform extrusion apparatus is made by producing a rotary wheel 10 having formed in its peripheral parts a continuous radially-extending groove, and securing in that groove an annular metal mass 76; rotating the wheel about its axis; and applying to the periphery of the annular metal mass an abutment members (36, Fig. 1) of predetermined end shape, and progressively advancing the abutment member in a radial direction as the wheel rotates whereby to machine in the peripheral parts of the metal mass a working groove 12 of predetermined cross-section, the peripheral parts of the annular metal mass being a composition which is substantially the same as that of a feedstock metal that is to be extruded in a said apparatus when equipped with the wheel member so produced. <IMAGE>

Description

SPECIFICATION Continuous extrusion of metals This invention relates to an apparatus for effecting continuous extrusion of metal from a feedstock in particulate, comminuted or solid form, which apparatus includes: (a) a rotatable wheel member arranged for rotation when in operation by a driving means, said wheel member having formed peripherally thereon a continuous circumferential groove; (b) a cooperating shoe member which extends circumferentially around a substantial part of the periphery of said wheel member and which has a portion which projects in a radial direction partly into said groove with small transverse working clearance from the side walls of said groove, said shoe member portion defining with the walls of said groove an enclosed passageway extending circumferentially of said wheel member;; (c) feedstock inlet means disposed at an inlet end of said passageway for enabling feedstock to enter said passageway at said inlet end whereby to be engaged and carried frictionally by said wheel member, when rotating, towards the opposite, outlet end of said passageway; (d) an abutment member carried on said shoe member and projecting radially into said passagway at said outlet end thereof so as to substantially close said passageway at that end and thereby impede the passage of feedstock frictionally carried in said groove by said wheel member, thus creating an extrusion pressure in said passageway at said outlet end thereof; and (e) a die member carried on said shoe member and having a die orifice opening from said passageway at said outlet end thereof, through which orifice feedstock carried in said groove and frictionally compressed by rotation of said wheel member, when driven, is compressed and extruded in continuous form, to exit from said shoe member via an outlet aperture.

In operating such an extrusion apparatus, the parts defining said passageway adjacent said outlet end thereof suffer very great compressive loads and very high operating temperatures. Of such highly stressed (mechanically and thermally) parts, those that suffer greatest wear are the stationary, feedstock-engaging parts of, or associated with, said stationary shoe member, particularly on said abutment member, said die member and the stationary parts that support those items.

For the convenience of readily making good worn surfaces or parts, the abutment member, and the die member and its supporting parts are made as separate replaceable items which are rigidly but removably secured in the stationary shoe member.

In order to reduce the temperatures at which those replaceable items operate, such items have been provided with internal cooling passages through which cooling water has been circulated.

However, such cooling measures have not been very effective, for the reasons that (a) the small sizes of those items and the high mechanical loads to which they are subjected have severely restricted the sizes of the internal cooling passages, and consequently the cooling water flow rates, to low values, and (b) the materials used for such small items (e.g. high-speed tool steels) have relatively poor heat transmission properties.

As a consequence of the low dissipation of heat by the cooling water, plastic flow of the tip of the abutment member, at its frde end adjoining the bottom of the groove in the wheel member, has been experienced, due to the excessive tip temperatures reached. This has severely limited the life of the abutment member, and the running time of the apparatus between successive occasions when the abutment member has to be replaced. This in turn has led to a reduction in the quantity of the output extrusion product produced, due to the down-time during which the apparatus cannot be operated.

After experimentation with various different arrangements of internal cooling passages, particularly in the abutment member, highly satisfactory results have now been achieved by means of an entirely different arrangement for cooling the abutment member.

According to the present invention, in a continuous extrusion apparatus of the kind referred to above in the first paragraph of this description, a jet of cooling fluid is directed from a nozzle directly on to the abutment tip portion from a rearward position disposed downstream of the abutment member (i.e. on the side thereof remote from the slug of compressed metal which lies against its upstream or front face). This jet is thus directed at the parts of the abutment member at which most of the frictional heat is generated, so that the cooling fluid is caused to flow directly over and in contact with those parts of the abutment member which would otherwise reach the greatest operating temperatures.With such an arrangement, there is no need to provide in the abutment member internal cooling passages, so that the ability of that member to withstand the high mechanical loads imposed on it is not impaired. Moreover, much less reliance is placed upon the heat transmission properties of the material from which the abutment member is made.

Highly satisfactory operation of a continuous extrusion apparatus has been achieved after adapting this method of cooling the abutment member, and for periods substantially greater than those achieved with those prior abutment cooling arrangements involving the use of internal cooling passages.

A further problem that has been encountered in the operation of continuous extrusion apparatus as mentioned above in the first paragraph of this description is that of handling and controlling the unwanted extrusion of metal near the outlet end of said passageway through the axial gaps which provide the necessary working transverse clearances between the side walls of the said groove and the cooperating, opposing surfaces of the said shoe member portion which projects radially into said groove. That extrusion if not properly controlled can produce continuous compacted waste strips of metal of very substantial cross-section and strength. Such waste strips, which are referred to in the art as "flash", can be difficult and somewhat dangerous to handle and control. Moreover, the apparatus has needed to be shut down so as to enable the flash to be removed by hack-sawing or shearing.

The unwanted extrusion of such waste strips can impose a force tending to widen the said gaps through which that unwanted extrusion takes place, which in turn leads to increases in the thickness of the said waste strips, and ultimately damage to the said wheel member and/or said shoe member.

Furthermore, the increased frictional drag exerted on said wheel member by the waste extruded metal present in the said clearance gaps requires an increase in the torque for driving the wheel member, and adds to the heat generated by friction and the operating temperatures of the various parts of the cooperating wheel and shoe members.

In addition, the size of said waste strips and the difficulty of handling them necessitates the quite frequent stopping of the apparatus for the purpose of removing those strips, since they cannot be safely handled and removed while the apparatus is in operation.

According to a second aspect of the present invention, the said wheel member is provided on each side of said groove with at least one tooth member positioned and disposed so as to intercept during rotation of said wheel member the waste strip being extruded through the said clearance gap at the adjacent side of the groove when that strip has grown sufficient to extend a predetermined distance from said groove, interception of such a waste strip by a said tooth member being effective to break away and free a portion of said waste strip.

Preferably, a plurality of such tooth members is provided on each side of said groove, the tooth members being spaced, preferably uniformly, around the wheel member.

The tooth members on one side of said groove may be disposed directly opposite corresponding tooth members disposed on the opposite side of said groove; or alternatively, the tooth members on one side of said groove may be staggered relative to corresponding tooth members disposed on the opposite side of said groove.

Said tooth members may project radially from said wheel member so as to intercept an extruded waste strip that is confined to grow in an axial or transverse direction by cooperating opposed surfaces on said wheel and shoe members respectively.

Alternatively, cooperating opposed surfaces on said wheel and shoe members respectively may confine said extruded waste strips to grow from said clearance gaps in directions which are oblique to the axis of rotation of said wheel member, in which case each said tooth member may be aligned in a radial or in an axial direction relative to said wheel member.

According to yet another aspect of the present invention, said shoe member portion which extends in a radial direction partly into said groove has its surface which faces the bottom of said groove shaped so that the radial distance of that surface from the bottom surface of said grove (as defined by the said abutment member) decreases progressively towards said outlet end of said passageway, at least over a predetermined zone adjacent said abutment, in which zone said feedstock material is in a fully compacted condition and without any voids.

By this means there is achieved in said zone, when feedstock in particulate or communuted form is supplied to said passageway, a metal flow pattern more closely resembling that achievable with feedstock in solid form.

Other features and advantages of the present invention will appear from a reading of the description that follows hereafter, and from the claims appended at the end of that description.

One continuuous extrusion apparatus embodying the various aspects of the present invention will now be described by way of example and with reference to the accompanying diagrammatic drawings in which: Figure 1 shows a medial, vertical cross-section taken through the essential working parts of the apparatus, the plane of that section being indicated in Fig. 2 at l-l; Figure 2 shows a transverse sectional view taken on the section indicated in Fig. 1 at ll-ll; Figures 3 and 4 show in sectional views similar to that of Fig. 2 two arrangements which are alternatives to that of Fig. 2; Figure 5 shows a schematic block diagram of a system embodying the apparatus of the Figs.

1 and 2; Figure 6 shows a graph depicting the variation of a heat extraction rate with variation of a cooling water flow rate, as obtained from tests on one apparatus according to the present invention; Figures 7 to 9 show, in views similar to that of Fig. 2, various modified forms of a wheel member incorporated in said apparatus; and Figure 10 shows, in a view similar to that of Fig. 1, a modified form of the apparatus shown in the Figs. 1 and 2.

Referring now to Figs. 1 and 2, the apparatus there shown includes a rotatable wheel member 10 which is carried in bearings (not shown) and coupled through gearing (not shown) to an electric driving motor (not shown) so as to be driven when in operation at a selected speed within the range 0 to 20 RPM (though greater speeds are possible).

The wheel member has formed around its periphery a groove 12 whose radial cross-section is depicted in Fig. 2. The deeper part of the groove has parallel annular sides 14 which merge with a radiused bottom surface 16 of the groove. A convergent mouth part 18 of said groove is defined by oppositely-directed frusto-conical surfaces 20, 22.

A stationary shoe member 24 carried on a lower pivot pin 26 extends around and cooperates closely with approximately one quarter of the periphery of the wheel member 10. The shoe member is retained in its operating position as shown in Fig. 1 by a withdrawable stop member 28.

The shoe member includes centrally (in an axial direction) a circumferentially-extending projecting portion 30 which projects partly into the groove 12 in the wheel member 10 with small axial or transverse clearance gaps 32, 34 on either side. That projecting portion 30 is constituted in part by a series of replaceable inserts, and comprises a radially-directed abutment member 36, an abutment support 38 downstream of the abutment member, a die block 40 (incorporating an extrusion die 42) upstream of the abutment member, and an arcuate wear-resisting member 44 upstream of said die block. Upstream of the member 44 an integral entry part 46 of the shoe member completes an arcuate passageway 48 which extends around the wheel member from a vertically-oriented feedstock inlet passage 50 disposed below a feedstock hopper 52, downstream as far as the front face 54 of the abutment member 36.That passageway has a radial cross-section which in the Fig. 2 is defined by the annular side walls 14 and bottom surface 16 of the groove 12, and the inner surface 56 of the said central portion 30 of the shoe member 24.

The said abutment member 36, die block 40, die 42 and arcuate member 44 are all made of suitably hard, wear-resistant metals, e.g. high-speed tool steels.

The shoe member is provided with an outlet aperture 58 which is aligned with a corresponding aperture 60 formed in the die block 40 and through which the extruded output metal product (e.g. a round wire) from the orifice of the die 42 emerges.

On rotation of the wheel member 10, comminuted feedstock admitted to the inlet end of the said arcuate passageway 48 from the hopper 52 via the inlet passage 50 is carried by the moving groove surfaces of the wheel member in an anti-clockwise direction as seen in Fig. 1 along the length of said arcuate passageway 48, and is agglomerated and compacted to form a solid slug of metal devoid of interstices in the lower section of the passageway adjacent said die block 40. That slug of metal is continuously urged under great pressure against the abutment member by the frictional drag of the moving groove surfaces. That pressure is sufficient to extrude the metal of said slug through the orifice of the extrusion die and thereby provide an extruded output product which issues through the apertures 58 and 60 in the shoe member and die block.In the particular case, the output product comprises a bright copper wire produced from small chopped pieces of wire which constitute the said feedstock.

A water pipe 62 secured around the lower end of the shoe member 24 has an exit nozzle 64 positioned and secured on the side of the shoe member that lies adjacent the wheel member 10. The nozzle is aligned so as, when the pipe is supplied with cooling water, to direct a jet of water directly at the downstream parts of the abutment member where it lies in and abuts the groove 12 in the wheel member 10. Thus, the tip of the free end of the abutment member (where in operation most of the heat is generated) and the adjoining surfaces of the wheel member and groove are directly cooled by the flow thereover of water from the jet directed towards them.

The die block 40 is provided with internal water passages (not shown) and a supply of cooling water for enveloping the output product leaving the die and extracting some of the heat being carried away in that product. But no such internal passages are formed in the abutment member. Thus, the strength of that member is not reduced in the interests of providing internal water cooling for cooling that member.

If desired, the cooling of the apparatus may be enhanced by providing cooling water sprinklers 65 over the hopper 52 so as to feed some cooling water into the said arcuate passageway 48 with the comminuted feedstock.

In the Fig. 2, the slug of compacted metal in the extrusion zone adjacent the die block 40 is indicated at 66. From that metal slug, the output product is extruded through the extrusion die 42 by the pressure in that zone. That pressure also acts to extrude some of the metal through the said axial clearance gaps 32 and 34 between the side walls of the groove and the respective opposing surfaces of the die block and abutment member. That extruded metal gradually builds up in a radial direction to form strips 68 of waste metal or "flash". In order to prevent those waste strips growing too large to handle and control, a plurality of transverselydirected teeth 70 are secured on the divergent walls 20, 22 which constitute the said mouth 18 of the groove 12.Those teeth are uniformly spaced around the wheel member, the teeth on one of the walls being disposed opposite the corresponding teeth on the opposite wall. If desired, the teeth on one wall may alternatively be staggered relative to corresponding teeth on the other wall.

In operation, the inclined surfaces 72 of the die block 40 deflect the extruded waste strips 68 obliquely into the paths of the respective sets of moving teeth 70. interception of such a waste strip 68 by a moving tooth causes a piece of that strip to be cut or otherwise torn away from the extruded metal in the clearance gap. Thus, such waste extruded strips are removed as soon as they extend radially far enough to be intercepted by a moving tooth. In this way the "flash" is prevented from reaching unmanageable proportions.

The said teeth do not need to be sharp, and can be secured in any satisfactory manner on the wheel member 10, e.g. by welding.

In the Figs. 3 and 4 are shown other teeth fitted in analogous manners to appropriate surfaces of other forms of said wheel member 10.

In those alternative arrangements, the external surfaces of the wheel member 10 cooperate with correspondingly shaped surfaces of the cooperating shoe member 24 whereby to effect control of the flash in a particular desired way. In Fig. 3, the flash is caused to grow in a purely transverse or axial direction, until it is intercepted by a radially projecting tooth, whereupon that piece of flash is torn away from the extruded metal in the associated clearance gap.

In Fig. 4, the flash is caused to grow in an oblique direction (as in the case of Fig. 2), but is intercepted by teeth which project radially from the surface of the wheel member 10.

Referring now to the Fig. 5, the system there shown includes at reference 100 a continuous extrusion apparatus as just described above, the output copper wire produced by that apparatus being indicated at 102, and being drawn through a sizing die 104 (for reducing its gauge to a desired lower value) by a tensioning pulley device 106 around which the wire passes a plurality of times before passing via an accummulator 108 to a coiler 110.

The pulley device 106 is coupled to the output shaft of an electrical torque motor 112 whose energisation is provided and controlled by a control apparatus 114. The latter is responsive to (a) a first electrical signal 116 derived from a wire tension sensor 118 which engages the wire 102 at a position between the extrusion apparatus 100 and the sizing die 104, and which provides as said first signal an electrical signal dependent on the tension in the wire 102 at the output of the extrusion apparatus 100; and to (b) a second electrical signal 120 derived from a temperature sensor 122 which measures the temperature of the wire 102 as it leaves the extension apparatus 100.

The control apparatus 114 incorporates a function generator 124 which is responsive to said second (temperature) signal 120 and provides at its output circuit a third electrical signal representative of the yield stress tension for the particular wire 102 when at the particular temperature represented by the said second (temperature) signal. That third electrical signal 126 is supplied as a reference signal to a comparator 128 (also part of said control apparatus) in which the said first (tension) signal 116 is compared with said third signal (yield stress tension).

The output signal of the comparator consititutes the signal for controlling the energisation of the torque motor.

In operation, the torque motor is energised to an extent sufficient to maintain the tension in the wire leaving the extrusion apparatus 100 at a value which lies a predetermined amount below the yield stress tension for the particular wire at the particular temperature at which it leaves the extrusion apparatus.

Whereas in the description above reference has been made to the use of a water jet for cooling the abutment member tip, jets of other cooling liquids (or even cooling gases) could be used instead. Even jets of appropriate liquidied gases may be used.

Regarding the flash-removing teeth 70 referred to in the above description, it should be noted that: (a) the shaping of the leading edge (i.e. the cutting or tearing edge) of each tooth is not critical, as long as the desired flash removal function is fulfilled; (b) the working clearance between the tip of each tooth 70 and the adjacent opposing surface of the stationary shoe member 24 is not critical, and is typically not greater than 1 to 2 mm, according to the specific design of the apparatus; (c) the greater the number of teeth spaced around each side of the wheel member 10, the smaller will be the lengths of "flash" removed by each tooth; (d) the teeth may be made of any suitable material, such as for example, tool steel; and (e) any convenient method of securing the teeth on the wheel member may be used.

The aspect of the invention referred to on page 6 at lines 12 to 26 is particularly beneficial in cases where the feedstock is in particulate form. By its use with such feedstocks, the metal flow pattern achieved in the zone in front of said abutment member and adjoining said die member is similar to that achieved in that zone in cases where said feedstock is in solid form.

Whereas in the above description, the wheel member 10 is driven by an electric driving motor, at speeds within the stated range, other like-operating continuous extrusion machines may utilise hydraulic driving means and operate at appropriate running speeds.

As an alternative to introducing additional cooling water into the passageway 48 via the sprinklers 65, hopper 52 and passage 50, such additional cooling water may be introduced into that passageway (for example, via a passage 67 formed in the shoe member 24) at a position at which said passageway is filled with particulate feedstock, but at which said particulate feedstock therein is not yet fully compacted.

It is believed that the highly beneficial mode of cooling referred to above in the first statement of invention (page 3, lines 18-26) and subsequently described above with reference to the drawings arises principally from the fact that the heat absorbed by a part of the wheel member lying temporarily adjacent the hot metal in the confined extrusion zone upstream of the abutment member is conveyed (both by thermal conduction and rotation of the wheel member) from that hot zone to a cooling zone situated downstream of the abutment member, in which cooling zone a copious supply of cooling fluid is caused to flow over relatively large areas of the wheel member passing through that cooling zone so as to extract therefrom a high proportion of the heat absorbed the wheel member in the hot extrusion zone.

In this cooling zone access to the wheel member is less restricted, and relatively large surfaces of that member are freely available for cooling purposes. This is in direct contrast to the extremely small and confined cooling surfaces that can be provided directly adjacent the extrusion zone in the parts of the said shoe member (i.e. the die block and abutment member) that bound that extrusion zone. As has been mentioned above, the cooling surfaces that can be provided in those parts are severely limited in size by the need to conserve the mechanical strengths of those parts and so enable them to safely withstand the extrusion pressure exerted on them.

The conveying of heat absorbed by the wheel member to the said cooling zone can be greatly enhanced by the incorporation in said wheel member of metals having good thermal conductivities and good specific heats (per unit volume). However, since the said wheel member, for reasons of providing adequate mechanical strength, is made of physically strong metals, (e.g.

tool steels), it has relatively poor heat transmission properties. Thus, the ability of the wheel member to convey heat to said cooling zone can be greatly enhanced by incorporating intimately in said wheel member an annular band of a metal having good thermal absorption and transmission properties, for example, a band of copper.

Such a thermally conductive band may conveniently be constituted by an annular band secured in the periphery of the said wheel member and preferably constituting, at least in part, the part of said wheel member in which the said circumferential groove is formed to provide (with the shoe member) the said passageway (48).

In cases where the extrusion product of the machine is of a metal having suitably good thermal properties, the said thermally conductive band may be composed of the same metal as the extrusion product (e.g. copper).

In other cases, said thermally-conductive band may be embedded in, or be overlaid by, a second annular band, which second band is of the same metal as the extrusion product of the machine and is in contact with the tip portion of the said abutment member, the two bands being of different metals.

Metals which may be used for the said thermally-conductive band are selected to have a higher product of thermal conductivity and specific heat per unit volume than tool steel, and include the following (in decreasing order of said product): Copper, silver, beryllium, gold, aluminium, tungsten, rhodium, iridium, molybdenum, ruthenium, zinc and iron.

The rate at which heat can be conveyed by such a thermally-conductive band from the extrusion zone to the cooling zone is dependent on the radial cross-sectional area of the band, and is increased by increasing that cross-sectional area. Thus, for a given cross-sectional dimension measured transversely of the circumference of the wheel member, the greater the radial depth of a said band, the greater the rate at which heat will be conveyed to the cooling zone by the wheel member.

Calculations have shown that for a said wheel member having an effective diameter of 233 mm, and a speed of rotation of 10 RPM, and a said thermally-conductive band of copper having a radial cross-section of U-shape, the rate "R" of conveying heat from the extrusion zone to the said cooling zone by the wheel member, by virtue of its rotation alone, varies in the manner shown below with variation of the radial depth or extent to which a said abutment (36) cooperating with the wheel member penetrates into that copper band, that is to say, with variation of the radial thickness "T'' of the copper band that remains at the bottom of the said circumferential groove (12).These calculations were based on a said copper band having with the adjacent parts (tool steel) of the wheel member an interface of generally circular configuration as seen in a radial cross section. Hence, the radial cross-sectional area "A" of the copper band varies in a non-linear manner with the said radial thickness "T" of copper at the bottom of said groove (12).

T (mm) A (sq. mm) R (kW) 1.0 18.0 5.1 1.5 22.7 6.4 2.0 27.4 7.7 2.5 32.1 9.1 3.0 36.8 10.4 In one practical arrangement having such a wheel member and a 2 mm radial thickness T of said copper band at the bottom of said groove (12), when operating at said wheel member speed and extruding copper wire of 1.4 mm diameter at a speed of 150 metres per minute, heat was extracted from the wheel member and abutment member in said cooling zone at a rate of 10 kW by cooling water flowing at as low a rate of 4 litres per minute and providing at the surfaces to be cooled in said cooling zone a jet velocity of approximately 800 metres per minute.

This heat extraction rate indicates that heat was reaching the cooling zone at a rate of some 2.3 kW as a result of the conduction of heat through the said conductive band, the adjacent wheel member parts, and the abutment member, induced by the temperature gradient existing between the extrusion zone and the cooling zone.

This measured rate of extracting heat by the cooling water flowing in the cooling zone compares very favourably with a maximum rate of heat extraction of some 1.9 kW that has been found to be achievable by flowing cooling water in the prior art manner through internal cooling passages formed in the abutment member.

Fig. 6 shows the way in which the rate of extracting heat from the wheel member and abutment member in said cooling zone was found to vary with variation of the rate of flow of the cooling water supplied to that zone.

The extrusion machine described above with reference to the drawings was equipped for the practical tests with a said thermally-conductive band of copper, which band is shown at reference 74 in Fig. 10, and indicated, for convenience only, in dotted-line form in Fig. 2. (It should be noted that Fig. 2 also depicts, when the copper band 74 is represented in full-line form, the transverse sectional view taken on the section indicated in Fig. 10 at ll-ll.) As will be understood from reference 74 in Fig. 2, the said copper band had a radial cross section of U-shape, which band lined the rounded bottom 16 of the circumferential groove 12 and extended partway up the parallel side walls of that groove.

Fig. 7 shows in a view similar to that of Fig. 2 a modification of the wheel member 10. In that modification, a solid annular band 76 of copper having a substantially rectangular radial cross-section is mounted in and clamped securely between cooperating steel cheek members 78 of said wheel member, so as to be driven by said cheek members when a driving shaft on which said cheek members are carried is driven by said driving motor. The band 76 has, at least intially, a small internal groove 76A spanning the tight joint 78A between the two cheek members 78. That groove prevents the entry between those cheek members of any of the metal of said band 76 during assembly of the wheel member 10. Complementary frusto-conical surfaces 76B and 78B on said band and cheek members respectively permit easier assembly and disassembly of those parts of the wheel member 10.

The circumferential groove 12, is formed in the copper band by pivotally advancing the shoe member 24 about its pivot pin 26 towards the periphery of the rotating wheel member 10, so as to bring the tip of the abutment member 36 into contact with the copper band, and thereby cause it to machine the copper band progressively deeper to form said groove 12 therein.

Fig. 8 shows an alternative form of said modification of Fig. 7, in which alternative the thermally-conductive band comprises instead a composite annular band 80 in which an inner core 82 of a metal (such as copper) having good thermal properties is encased in and in good thermal relationship with a sheath 84 of a metal (for example, zinc) which is the same as that to be extruded by the machine.

Fig. 9 shows a further alternative form of said modification of Fig. 7, in which alternative the thermally-conductive band comprises instead a composite band 86 in which a radially-inner annular part 88 thereof is made of a metal (such as copper) having good thermal properties and is encircled, in good thermal relationship, by a radially-outer annular part 90 of a metal which is the same as that to be extruded by the machine. Said circumferential groove is machined by said abutment member wholly within said radially-outer part 90 of said band.

Metals which can be extruded by extrusion machines as described above include: Copper and its alloys, aluminium and its alloys, zinc, silver, and gold.

Claims (10)

1. Apparatus for effecting continuous extrusion of metal from a feedstock in particulate, comminuted or solid form, which apparatus includes: (a) a rotatable wheel member arranged for rotation when in operation by a driving means, said wheel member having formed periphery thereon a continuous circumferential groove; (b) a cooperating shoe member which extends circumferentially around a substantial part of the periphery of said wheel member and which has a portion which projects in a radial direction partly into said groove with small transverse working clearance from the side walls of said groove, said shoe member portion defining with the walls of said groove an enclosed passageway extending circumferentially of said wheel member;; (c) feedstock inlet means disposed at an inlet end of said passageway for enabling feedstock to enter said passageway at said inlet end whereby to be engaged and carried frictionally by said wheel member, when rotating, towards the opposite, outlet end of said passageway; (d) an abutment member carried on said shoe member and projecting radially into said passageway at said outlet end thereof so as to substantially close said passageway at that end and thereby impede the passage of feedstock frictionally carried in said groove by said wheel member, thus creating an extrusion pressure in said passageway at said outlet end thereof;; (e) a die member carried on said shoe member and having a die orifice opening from said passageway at said outlet end thereof, through which orifice feedstock carried in said groove and frictionally compressed by rotation of said wheel member, when driven, is compressed and extruded in continuous form, to exit from said shoe member via an outlet aperture; and (f) cooling means disposed immediately downstream of said abutment member and arranged for connection, when the apparatus is in operation, to a source of cooling fluid under pressure, said cooling means being arranged to direct cooling fluid from said source at an external cooling surface of at least said abutment member, which cooling surface is exposed for cooling at and accessible from the downstream side of said abutment member.

2. Apparatus according to Claim 1, wherein said cooling means is also arranged to simultaneously direct cooling fluid from said source at an external, peripheral cooling surface of said wheel member, which cooling surface is exposed for cooling immediately downstream of said abutment member.

3. Apparatus according to Claim 1 or Claim 2, wherein said cooling means includes a nozzle disposed and arranged to direct a jet of said cooling fluid on to a said cooling surface of said abutment member at its free end, which end lies projecting into said groove on said wheel member.

4. Apparatus according to Claim 3, wherein said nozzle is disposed and arranged to direct a jet of said cooling fluid partly on to said surface of said abutment member and partly on to external surfaces of said wheel member and groove which lie adjacent said abutment member.

5. Apparatus according to Claim 3 or Claim 4, wherein said nozzle is disposed and arranged to direct said jet along an exposed surface of an abutment supporting member which is disposed downstream of said abutment member and which supports said abutment member against said extrusion pressure developed upstream thereof, said jet shrouding and cooling said abutment supporting member as well as at least said abutment member.

6. Apparatus according to any one of the Claims 3 to 5, wherein said nozzle is constituted by the open end of a cooling fluid pipe which is secured on said shoe member, said pipe being arranged for connection at its other end to a said source of cooling fluid under pressure.

7. Apparatus according to any preceding claim, wherein said shoe member is pivotally mounted on a transverse pivot pin at a position downstream of said abutment member, and is provided with withdrawable retaining means arranged normally to maintain said shoe member in its operating position relative to said wheel member, withdrawal of said retaining means freeing said shoe member for pivotal movement relative to said wheel member whereby to give access to said passageway between its said inlet and outlet ends.

8. Apparatus according to any preceding claim, wherein said wheel member incorporates concentrically therein an annular, thermally-conductive band of a metal having good heat absorption and transmission properties, said band being in good thermally-conducting relationship with the parts of said wheel member which bound and define said circumferential groove, and said band serving to absorb heat generated in the extrusion zone immediately upstream of said abutment member and to transmit it to a cooling zone immediately downstream of said abutment member for absorption there by said cooling fluid.

9. Apparatus according to Claim 8, wherein said thermally-conductive band constitutes said parts of said wheel member which bound and define said circumferential groove, and said band is formed of a metal which is the same as the metal of said feedstock.

10. A method according to any of the Claims 1 to 7, substantially as hereinbefore described with reference to and as illustrated by any single figure or group of associated figures of the accompanying diagrammatic drawings.

10. Apparatus according to Claim 8, wherein said thermally-conductive band is sheathed in a second annular band, which second band constitutes said parts of said wheel member which bound and define said circumferential groove, and which second band isolates said thermallyconductive band from said groove and feedstock disposed therein, and is formed of a metal which is the same as the metal of said feedstock, the metal of said thermally-conductive band being different from said metal of said feedstock.

11. Apparatus according to Claim 8, wherein said thermally-conductive band is overlaid by a second annular band, which second band constitutes said parts of said wheel member which bound and define said circumferential groove, and which is second band isolates said thermallyconductive band from said groove and feedstock disposed therein, and is formed of a metal which is the same as the metal of said feedstock, the metal of said thermally-conductive band being different from said metal of said feedstock.

12. Apparatus according to any one of the Claims 9 to 11, wherein said circumferntial groove is formed in a said annular band by a machining process in which metal of said band is removed, so as to form said groove, by progressively urging said abutment member when carried in said shoe member (or the equivalent thereof) deeper into the metal of said band.

13. Apparatus according to any preceding claim, wherein said cooling means also includes cooling fluid admission means arranged for admitting cooling fluid from a supply source into said passageway at or near said inlet end thereof.

14. Apparatus according to Claim 13, wherein said feedstock inlet means includes means arranged for admitting to said passageway at said inlet end thereof feedstock in particulate or comminuted form only, and wherein said cooling fluid admission means includes means arranged for admitting cooling fluid into said passageway with said particulate or comminuted feedstock at said inlet end.

15. Apparatus according to Claim 13, wherein said feedstock inlet means includes means arranged for admitting to said passageway at said inlet end thereof feedstock in particulate or comminuted form only, and wherein said cooling fluid admission means includes a fluid duct disposed in and passing through said shoe member, said duct being disposed and arranged to admit cooling fluid from a said source via said shoe member projecting portion into said passageway at a position intermediate said inlet and outlet ends thereof, at which position said feedstock in said passageway substantially fills said passageway but is not fully compacted therein.

16. Apparatus to any preceding claim, substantially as hereinbefore described with reference to and as illustrated by any relevant single figure or group of associated figures in the accompanying diagrammatic drawings.

17. Apparatus for effecting continuous extrusion of metal from a feedstock in particulate, comminuted or solid form, which apparatus includes: (a) a rotatable wheel member arranged for rotation when in operation by a driving means, said wheel member having formed peripherally thereon a continuous circumferential groove; (b) a cooperating shoe member which extends circumferentially around a substantial part of the periphery of said wheel member and which has a portion which projects in a radial direction partly into said groove with small transverse working clearance from the side walls of said groove, said shoe member portion defining with the walls of said groove an enclosed passageway extending circumferentially of said wheel member;; (c) feedstock inlet means disposed at an inlet end of said passageway for enabling feedstock to enter said passageway at said inlet end whereby to be engaged and carried frictionally by said wheel member, when rotating, towards the opposite, outlet end of said passageway; (d) an abutment member carried on said shoe member and projecting radially into said passageway at said outlet end thereof so as to substantially close said passageway at that end thereby impede the passage of feedstock frictionally carried in said groove by said wheel member, thus creating an extrusion pressure in said passageway at said outlet end thereof;; (e) a die member carried on said shoe member and having a die orifice opening from said passageway at said outlet end thereof, through which orifice feedstock carried in said groove and frictionally compressed by rotation of said wheel member, when driven, is compressed and extruded in continuous form, to exit from said shoe member via an outlet aperture; and (f) flash-removing means secured on said wheel member for rotation therewith and arranged to periodically intercept and thereby forcibly detach sections of a waste material (hereinafter referred to as "flash") that is being continuously extruded (when the apparatus is in operation) through one or both of two axial gaps which provide the said small transverse working clearances between the said side walls of said groove and the cooperating surfaces of said shoe member portion which projects radially into said groove.

18. Apparatus according to Claim 17, wherein said flash-removing means includes on each side of said groove at least one tooth member positioned and disposed so as to intercept, during rotation of said wheel member, the flash being extruded through the said axial gap at the adjacent side of said groove when that flash has grown so as to extend a predetermined distance from said axial gap, interception of said flash by a said tooth member being effective to detach a said second of said flash.

19. Apparatus according to Claim 18, wherein said flash-removing means includes on each side of said groove a plurality of such tooth members spaced uniformly around said wheel member.

20. Apparatus according to Claim 18 or Claim 19, wherein the or each said tooth member positioned on one side of said groove is staggered circumferentially relative to the corresponding tooth member positioned on the opposite side of said groove.

21. Apparatus according to any one of the Claims 18 to 20, wherein each said tooth member projects from said wheel member in a generally radial direction whereby to intercept flash that is being extruded through the associated axial gap in a direction which is oblique to, or parallel with, the axis of rotation of said wheel member.

22. Apparatus according to any one of the Claims 18 to 20, wherein each said tooth member projects from said wheel member in a generally axial direction whereby to intercept flash that is being extruded through the associated axial gap in a direction which is oblique to the axis of rotation of said wheel member.

23. Apparatus according to any one of the Claims 18 to 22, wherein each said tooth member is constituted as a cutting tool arranged for cutting off sections of said flash.

24. Apparatus according to any one of the Claims 17 to 23, substantially as hereinbefore described with reference to and as illustrated by any relevant single figure or group of associated figures in the accompanying diagrammatic drawings.

25. Apparatus for effecting continuous extrusion of metal from a feedstock in particulate or comminuted form, which apparatus includes: (a) a rotatable wheel member arranged for rotation when in operation by a driving means, said wheel member having formed peripherally thereon a continuous circumferential groove; (b) a cooperating shoe member which extends circumferentially around a substantial part of the periphery of said wheel member and which has a portion which projects in a radial direction partly into said groove with small transverse working clearance from the side walls of said groove, said shoe member portion defining with the walls of said groove an enclosed passageway extending circumferentially of said wheel member;; (c) feedstock inlet means disposed at an inlet end of said passageway for enabling feedstock in particulate or comminuted form to enter said passageway at said inlet end whereby to be engaged and carried frictionally by said wheel member, when rotating, towards the opposite, outlet end of said passageway; (d) an abutment member carried on said shoe member and projecting radially into said passageway at said outlet end thereof so as to substantially close said passageway at that end and thereby impede the passage of feedstock frictionally carried in said groove by said wheel member, thus creating an extrusion pressure in said passageway at said outlet end thereof; and (e) a die member carried on said shoe member and having a die orifice opening from said passageway at said outlet end thereof, through which orifice feedstock carried in said groove and frictionally compressed by rotation of said wheel member, when driven, is compressed and extruded in continuous form, to exit from said shoe member via an outlet aperture; and in which apparatus said passageway decreases gradually in radial depth in the direction of rotation of said wheel member through a zone which extends circumferentially from a position upstream of said die orifice to said abutment member, whereby to achieve in said zone, when feedstock in particulate or comminuted form is supplied to said passageway, a metal flow pattern more closely resembling that achievable with feedstock in solid form.

26. Apparatus according to Claim 25, wherein said shoe member portion is constituted adjacent said abutment member by an insert removably secured in said shoe member and extending circumferentially from said abutment member in a direction opposite to that of said wheel member rotation, which insert incorporates said die member, and which insert has a surface facing towards the bottom of said groove, which surface is shaped to provide said gradual decreases in radial depth of said passageway.

27. Apparatus according to Claim 26, wherein said surface of said insert comprises a plane surface inclined at a small angle to a tangent to the bottom of said groove.

28. Apparatus according to Claim 27, wherein said plane surface is inclined at a said angle such that the ratio of the area of said abutment member exposed to metal under said extrusion pressure to the radial cross-sectional area of said passageway at the upstream, entry end of said zone is substantially equal to the ratio of the apparent density of the feedstock entering said zone at said entry end thereof to the density of the fully compacted feedstock lying adjacent said abutment member.

29. Apparatus according to Claim 28, wherein said plane surface is inclined at a said angle such that the said area of said abutment member exposed to said metal is approximately half the said radial cross-sectional area of said passageway at said entry end of said zone.

30. Apparatus according to any one of the Claims 25 to 29, substantially as hereinbefore described with reference to and as illustrated by any relevant single figure or group of associ ated figures in the accompanying diagrammatic drawings.

31. A continuous extrusion system comprising: (a) a continuous extrusion apparatus of the kind referred to in the opening paragraph of this specification, arranged for producing a continuous extruded metal product; (b) a further die member through which, when the system is in operation, said metal product is threaded and drawn whereby to effect a desired change in the cross-section of said metal product; (c) a tensioning means arranged to apply, when the system is in operation, a tension to said metal product leaving said further die member whereby to continuously draw said product through said further die member; (d) a temperature-sensing means arranged to provide a temperature signal dependent upon the sensed temperature of said metal product as it leaves said apparatus;; (e) a tension-sensing means arranged to provide a tension feedback signal dependent upon the sensed tension in said metal product passing from said apparatus to said further die member; and (f) a control apparatus responsive to said temperature signal and said tension feedback signal and arranged to control said tensioning means automatically in a manner such that the sensed tension in said metal product leaving said apparatus does not exceed a predetermined safe value which is less than the yield stress tension of said metal product at the sensed temperature at which that product leaves said apparatus.

32. A system according to Claim 31, wherein said control apparatus includes: (i) a function generator responsive to said temperature signal and arranged to provide a tension reference signal representative of the yield stress tension for said metal product at said sensed temperature; and (ii) comparison means responsive differentially to said tension reference and feedback signals, and arranged to provide a control signal for controlling said tensioning means in dependence upon the difference of said tension reference and feedback signals.

33. A system according to Claim 31 or Claim 32, wherein said tensioning means incorporates an electrically energised torque motor, and said control apparatus is arranged to vary the electrical energisation of said torque motor.

34. A system according to any one of the Claims 31 to 33, substantially as hereinbefore described with reference to and as illustrated by any relevant single figure or group of associated figures in the accompanying diagrammatic drawings.

35. A system according to any one of the Claims 31 to 34, wherein said apparatus comprises an apparatus according to any one of the Claims 1 to 30.

Amendments to the claims have been filed, and have the following effect: Claims 1 to 35 above have been deleted or textually amended.

New or textually amended claims have been filed as follows:- CLAIMS

1. A method of producing a rotary wheel member adapted for use in a rotary, friction type, continuous extrusion apparatus, which method comprises the steps of: (a) producing a rotary wheel having formed in its cylindrical peripheral parts a continuous, radially-extending groove, and secured in that groove for movement with said peripheral parts of said wheel an annular metal mass; (b) rotating said wheel about its rotary axis; and (c) applying to the periphery of said annular metal mass secured in said wheel a tool of predetermined end shape, and progressively advancing said tool in a radial direction as said wheel continues to rotate whereby to machine in the peripheral parts of said annular metal mass a working groove of predetermined desired transverse cross sectional shape; said peripheral pats of said annular metal mass which define said working groove being of a composition which is substantially the same as that of a predetermined feedstock metal that is to be extruded in a said apparatus when equipped with the wheel member so produced; and said predetermined end shape of said tool being substantially the same as that of a predetermined abutment member which is to be used in that apparatus to close the end of an arcuate passageway which is formed in said working groove by a shoe member which when the apparatus is in operation co-operates with said cylindrical peripheral parts of said wheel member.

2. A method according to Claim 1, wherein said annular metal mass secured in said wheel groove is in good thermal relationship with said wheel.

3. A method according to Claim 1 or Claim 2, wherein said annular metal mass secured in said wheel groove comprises an annulus of a first predetermined metal lying concentrically with said wheel in said wheel groove and being enveloped within a sheath of a second predetermined metal, said second predetermined metal defining said working groove and being in good thermal relationship with said first predetermined metal.

4. A method according to Claim 1 or Claim 2, wherein said annular metal mass secured in said wheel groove comprises an annulus of a first predetermined metal lying concentric with said wheel in the bottom of said wheel groove and being overlaid by a second annulus of a second predetermined metal, said first predetermined metal being in good thermal relationship with said second predetermined metal, and said second predetermined metal defining said working groove.

5. A method according to Claim 3 or Claim 4, wherein said first and second predetermined metals each have a product of thermal conductivity and specific heat per unit volume that is greater than that of the material of the wheel.

6. A method according to Claim 5, wherein said product for said first predetermined metal is greater than that for second predetermined metal.

7. A method according to any preceding Claim, wherein said wheel is mounted for rotation in a said rotary extrusion apparatus, and is rotated therein, and said tool comprises a said abutment member of said apparatus, which abutment member is advanced radially into said annular metal mass as said wheel is rotated, whereby to form said working groove.

8. A wheel member prepared by a method according to any preceding claim.

9. A wheel member according to Claim 8, substantially as hereinbefore described with reference to and as illustrated by any single figure or group of associated figures of the accompanying diagrammatic drawings.