GB2083770A

GB2083770A - Extrusion apparatus

Info

Publication number: GB2083770A
Application number: GB8127514A
Authority: GB
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1980-09-16
Filing date: 1981-09-11
Publication date: 1982-03-31
Also published as: GB2083770B

Abstract

Apparatus for continuous extrusion, of the kind disclosed and claimed in our British Patent Specification No. 1,370,894 has a coining roller 11 at the feed point, a tangential tray 12 or feed channel supplying the coining roller, and a ram 14 cooperating with the feed tray for providing a force feed of material to the nip of the coining roller. Such apparatus is particularly suitable for the recovery of off-cuts of foils and other scrap. <IMAGE>

Description

SPECIFICATION Continuous extrusion This invention relates to continuous extrusion.

Our British Patent Specification No 1,370,894 discloses and claims a process and apparatus for the performance of continuous extrusion. Further developments of the basic technology disclosed in the said British Patent Specification No 1,370,894 have been disclosed and claimed in British Patent Specification Nos 1,434,201; 1,499,728; 1,504,890 and 1,506,845. In particular British Patent Specification No 1,434,201 discloses in Figure 4 and claims the provision in extrusion apparatus of a driven member arranged at the material feed point into the passageway and cooperating with the groove in the moveable member to form a nip for compacting loose material into a continuous strip of feed material prior to entering the passageway.

The present application is concerned with applying continuous extrusion, both process and apparatus, to the recovery of scrap material by forming it into suitable shapes and dimensions which allow of its economic recovery.

According to the present invention, apparatus for continuous extrusion as described and claimed in our British Patent Specification No 1,370,894 has a coining roller arranged at the material feed point into the passageway formed between the sides and floor of the groove and the shoe member which has a portion which projects into said groove so that the coining roller cooperates with the groove to form a nip for compacting loose material into a continuous coherent strip of feed material prior to entering the passageway; a tangentially arranged feed channel or tray arranged so as to feed material for extrusion into said passageway in advance of said coining roller; and a cyclically operated ram cooperating with the feed tray to provide a force feed of material to the nip of the coining roller in such a manner that feed is continuously maintained upstream of the said nip.

Furthermore there may be provided in addition a vibrator in contactwith said channel or tray.

The coining roller serves to pre-compact the feed material the better to provide it with sufficient cohesion to permit frictional forces to be generated sufficient for extrusion to be performed. The coining roller is advantageously of similar diameter to that of the grooved wheel and is preferably driven at the same peripheral speed as that of the grooved wheel.

The peripheral surface of the coining roller and, optionally, the side faces where the roller projects into'the wheel groove, may be roughened instead of piain.

The feed tray advantageously incorporates a hopper iso which the material for extrusion is fed.

To ensure that feed is continuously maintained upstream of the nip of the coining roller, the forward travel of the ram per unit of time, allowing for reverse strokes, is at least equal to the peripheral speed of the grooved wheel. Where it is greater, it is advantageous to provide a control system of the feed-backtype,to avoid excess build-up of feed material upstream of the coining roller nip.

Apparatus according to the invention is particular iy advantageous in recovering metals in foil form, especially the so-called 'noble' and expensive metals, silver, gold, and platinum. Off-cuts of foil and other surpluses can be recovered economically by employing them as feed material to such apparatus.

A particular construction of apparatus according to the invention will now be described with reference to the accompanyirig drawing, wherein the sore Figure is a diagrammatic side view partially in section. Only so much of the apparatus as is necessary for an understanding of the invention will be described and illustrated. Referring to the drawing, the apparatus, which is similar to the kind disclosed in Figure 3 of our British Patent Specification No 1,370,894, includes a wheel 1 having a peripheral groove 2 and means, not shown, for rotating the wheel in a clockwise direction for normal operation to perform extrusion as seen in the drawing. A stationary shoe 3 pivoted at 4 has a tooling part 5 which projects into the groove 2 of the wheel 1.The shoe 3 also has an abutment 6 which extends to the floor of the groove 2 and serves to block a passageway 7 formed by the sides and floor of the groove 2 and the tooling 5. A radial die 8 is arranged to communicate with the passageway 7 and is disposed immediately in front of the abutment 6, an outlet 9 from the die 8 being provided within the shoe 3. A removable restraint 10 serves to hold the shoe 3 so that the tooling 5 is in its correct position in which it engages with the groove 2 of the wheel 1.

The inlet to the passageway 7 is disposed at the position where the tooling 5 commences. Just in front of that position a driven coining roller 11 is situated with its centre adjustably provided on the body of the shoe 3. The coining roller 11 is as shown, advantageously of the same or similar diameter to that of the grooved wheel 1, is driven in counter direction to the wheel 1, anti-clockwise in the drawing, and is arranged so that its periphery projects into the groove of the wheel 1 to provide a nip which is adjustable in height by adjusting the centre ofthe roller 9 on the shoe 3 and which is at a maximum at the plane joining the centres of the extrusion wheel 1 and coining roller 11.

A feed tray 12 is arranged so as to extend to the inlet of the passageway 7. The tray 12 has a hopper 13 and a double acting ram 14 which can be operated reciprocably in order to feed material from the hopper 13 along the tray 12 to the nip of the coining roller 11 and into the passageway 7. A vibrator 15 is connected to the tray 12 to assist the movement of particulate material fed to the hopper 13to become positioned such that the ram 14will have a full charge of material when it operates in the feed direction. As an example, the ram is driven by a double-acting air operated cylinder so as to be reciprocated at a rate of up to 3,000-4,000 strokes, each of 1 Omm, per minute, this giving, assuming 100% packing density, a feed of 30-40 m/minute. A grooved wheel peripheral speed of up to this amount could therefore be employed.Either wheel speed or ram oscillation or both, can be controlled to avoid excess build-up of feed material in front of the coining roller, by a suitable control system (not shown) which can employ feed-back based on sensing excessive build-up and diminishing buildup.

In operation, material for recovery which can be in foil, scrap, swarf, comminuted or other condition is fed to the hopper 13 and by means of the ram 14 assisted by the vibrator 15 is fed to the nip of the coining roller 11.The latter causes it to become compacted within the groove 2 into a strip of 'green' material which, by the frictional force generated between this strip and the floor and sides of the groove 2, is urged along the passageway 7 until constrained by the abutment 6 to be extruded through the die 8 and extrude as metal product in solid form through the outlet 9 from whence it can be collected in coils or as expedient, for recovery in conventional manner.

A coining roller of the same or similar diameter to that of the extrusion wheel serves by its matching contact surface with that of the extrusion wheel, its matching profile with the groove of the extrusion wheel, and its matching peripheral speed with that of the extrusion wheel, to exert an equal deforming force by virtue of its reaction with the floor of the groove of the extrusion wheel to define a strip of compacted material from the hopper 13 which by the action of the coining roller is driven forward into close engagement with the floor and sides of the groove so that the frictional force there generated is in accordance with theory and is reproducable. It is advantageous in that it maximises throughput, it enables materials to be used for feed which might otherwise be difficult to extrude because of difficulty of achieving 'grip' in the passageway 7, and it reduces the drag which occurs between the feed material within the passageway 7 and the lower surface of the tooling 5.

An additional expedient which has been found effective for performing further pre-work on feed material prior to extrusion is the provision of a part-abutment 16 (in addition to the abutment 6) disposed upstream of the extrusion die 8, and manifest by a replaceable part of the tooling 5. This is shown in dot-and-dash lines in the drawing. The lower surface of the part-abutment 16 is in clearance from the floor of the wheel groove 2.

Claims

1. Apparatus for continuous extrusion as described and claimed in our British Patent Specification No 1,370,894, having a coining roller which is arranged at the material feed point into the passageway formed between the sides and floor of the groove and that portion of the shoe member which projects into said groove so that the coining roller cooperates with the groove to form a nip for compacting loose material into a continuous coherent strip of feed material prior to entering the passageway; a tangentially arranged feed channel or tray arranged so as to feed material for extrusion into said passageway in advance of said coining roller; and a cyclically operated ram cooperating with the feed tray to provide a force feed of material to the nip of the coining roller in such a manner that feed is continuously maintained upstream of the said nip.

2. Apparatus according to claim 1,wherein, in addition, a vibrator is provided in contact with said channel or tray.

3. Apparatus according to either of claims 1 and 2, wherein the coining roller is of similar diameter to that of the grooved wheel.

4. Apparatus according to any of the preceding claims, wherein the coining roller is driven at the same peripheral speed as that of the grooved wheel.

5. Apparatus according to any of the preceding claims, wherein the peripheral surface of the coining roller is roughened.

6. Apparatus according to claim 5, wherein in addition, the side faces of the coining roller where it projects into the wheel groove, are roughened.

7. Apparatus according to any of the preceding claims, wherein the feed tray incorporates a hopper to which the material for extrusion is fed.

8. Apparatus according to any of the preceding claims, wherein, to ensure that feed is continuously maintained upstream of the nip of the coining roller, the forward travel of the ram per unit time, allowing for reverse strokes, is at least equal to the peripheral speed of the grooved wheel.

9. Apparatus according to claim 8, wherein, where the said forward travel of the ram per unit time is greater than the peripheral speed of the grooved wheel, there is provided a control system for avoiding excess build-up of feed material upstream of the coining roller nip.

10. Apparatus according to any of the preceding claims, including, in addition to the normal abutment downstream of the extrusion die, a partabutment whose lower surface is in clearance from the floor of the wheel groove and which serves to impart additional pre-working to the feed material prior to extrusion.

11. Apparatus for performing continuous extrusion, substantially as hereinbefore described with reference to the accompanying drawing.