GB2329602A

GB2329602A - Method of producing a series of individual forged articles from feedstock produced on a continuous rotary extrusion machine and apparatus therefore

Info

Publication number: GB2329602A
Application number: GB9821023A
Authority: GB
Inventors: Stephen Thomas Kennedy; Carol Jayne Pindar; Andrew Timothy Cole
Original assignee: T&N Technology Ltd
Current assignee: Federal Mogul Technology Ltd
Priority date: 1997-09-30
Filing date: 1998-09-29
Publication date: 1999-03-31
Anticipated expiration: 2018-09-29
Also published as: ZA988869B; GB9821023D0; WO1999016560A1; GB9720607D0; GB2329602B; AU9179498A

Abstract

The present invention is directed to a method of producing a series of individual forged articles from a feedstock produced on a continuous rotary extrusion machine from metal powder supplied thereto; comprises repeating a cycle of steps, the steps being characterised by comprising, in any appropriate sequence:- i) extruding the feedstock into a tooling chamber 10 initially to form a blank in a mould chamber 12 comprising part of the tooling chamber, the mould chamber being moveable between a first position and a second position to separate the material in the mould chamber from the feedstock; ii) stopping extrusion of the feedstock; iii) moving the mould chamber 12 from the first position to the second position; iv) with the mould chamber in the second position, ejecting the material from the mould chamber; v) forging the blank to produce an article; and vi) moving the then hollow mould chamber from the second position to the first position.

Description

Method of producing a series of individual forged articles from feedstock produced on a continuous rotary extrusion machine; and apparatus operating in accordance with such a method.

The present invention relates to a method of producing a series of individual forged articles from feedstock produced on a continuous rotary extrusion machine from metal powder supplied thereto; and apparatus operating in accordance with such a method. The invention has particular, though not exclusive, application in the manufacture of piston pots.

A continuous rotary extrusion machine is described in GB-A-1370894.

It is known to employ a continuous rotary extrusion machine to extrude continuously a strip, or a tube, or a rod.

The present invention has as an advantage the production of a series of individual forged articles from extruded feedstock, produced on a continuous rotary extrusion machine.

According to the present invention, a method of producing a series of individual forged articles from a feedstock produced on a continuous rotary extrusion machine from metal powder supplied thereto comprises repeating a cycle of steps comprising, in any appropriate sequence:i) extruding the feedstock into a tooling chamber initially to form a blank in a mould chamber comprising part of the tooling chamber, the mould chamber at least partially being defined by a mould, the mould chamber being moveable between a first position and a second position to separate the material in the mould chamber from the feedstock; ii) stopping extrusion of the feedstock; iii) moving the mould chamber from the first position to the second position; iv) with the mould chamber in the second position, ejecting the material from the mould chamber; v) forging the blank to produce an article; and vi) moving the then hollow mould chamber from the second position to the first position.

According to another aspect the present invention comprises apparatus for the manufacture of a series of individual forged articles from extruded feedstock comprising a continuous rotary extrusion machine for the production of the feedstock from metal powder supplied thereto; the apparatus including a tooling chamber at least partially defined by a heated die and a mould, and the tooling chamber including an expansion zone and a mould chamber partially defined by the walls of the mould, a blank to be formed in the mould chamber, and the mould chamber being moveable transversely to the expansion zone; indexing means to move the mould chamber transversely to the expansion zone between a first position and a second position; means to stop extrusion of the feedstock; means to eject material from the mould chamber when the mould chamber is in the second position; and means to forge the blank.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 shows apparatus for producing forged articles according to one embodiment of the present invention; Figure 2 shows a plan view of part of the apparatus of Figure 1; Figure 3 corresponds to Figure 2, and shows a plan view of part of apparatus comprising a second embodiment of the present invention; and Figure 4 is a schematic view of the path of the extruded feedstock during production of forged articles by the apparatus of Figure 3.

Referring now to Figure 1 and Figure 2, a first apparatus for producing forged articles according to the invention will be described in more detail. There is shown a continuous rotary extrusion machine 1 including a hopper 2, a compaction wheel 3, an extrusion wheel 4, a shoe 5 and an abutment 6. The compaction and extrusion wheels are driven about their respective axes in the directions shown by the arrows. The compaction wheel 3 is provided with a male tongue (not shown) about its periphery. The extrusion wheel 4 is provided with a female groove 8 about its periphery. In use the male tongue and female groove 8 co-operate to form a channel to apply a preset pressure to the material flowing between the compaction wheel 3 and the extrusion wheel 4.

Continuous extruded feedstock is produced from metal powder 9 or similar, for example flakes or needles of metal. However, for convenience in this specification, and the accompanying claims, the extruded feedstock will be referred to as being produced from metal powder supplied to the continuous rotary extrusion machine. The metal powder is fed, via the hopper 2, into the chamber formed between the compaction wheel and the extrusion wheel. Means (not shown) is provided to heat the chamber. The metal is compacted in the chamber into a partially solid form. The material is carried in this form by rotation of the extrusion wheel1 between the extrusion wheel 4 and the shoe 5. Here material undergoes sufficient deformation and pressure to form a semi-solid extrusion stub. The continuous forming of the stub forms the head pressure of the machine. The stub is diverted by the abutment 6 and is extruded into a heated tooling chamber 10.

The heated tooling chamber 10 is defined by a heated die 11, a mould 12 and a former 14 located within a machine frame 17. The tooling chamber includes an expansion zone 15, expanding from a small aperture, at which the stub is extruded into the tooling chamber, to a relatively large diameter mould chamber defined by the mould walls.

One end of the tooling chamber is defined by the former 14, which may be moved between an advanced position within the mould 12, and a retracted position spaced from the mould, as indicated by the arrows in Figure 1. The former may be moved between these two positions hydraulically or by any other suitable means.

Sufficient material to form the article, for example a piston pot, is extruded into the expansion zone and, hence, also into the mould chamber. The former is driven to the advanced position, and the feed into the expansion zone is then stopped. In the embodiment shown, the former generates the internal profile of the pot. The former is then withdrawn.

The feed into the expansion zone 15 is stopped by a control system detecting a rise in current to a motor driving the compaction wheel 3 and/or the extrusion wheel 4 of the continuous rotary extrusion machine 1, because the heated tooling chamber 10 is filled At this point, the supply of metal powder 9 is halted to create a closed system within the continuous rotary extrusion machine 1. Since no new powder is added, no new extruded feedstock is produced and so supply of the feedstock to the expansion zone is temporarily halted. The feedstock within the continuous rotary extrusion machine 1 continues to be driven by the extrusion wheel, and in this way is kept in the semi-solid state.

The mould chamber is next indexed between a first and a second position in a direction transverse to the expansion zone 15 causing the extruded and forged material forming the piston pot to shear. When the mould chamber is at the second position, outside the machine frame 17, the piston pot can be ejected from the mould. Preferably, this may be done by using a vertical cylinder ejection device. The mould chamber is then reheated and fed back into the machine frame 17 to begin a fresh cycle of manufacture.

In the illustrated embodiment the mould defines a plurality of mould chambers, each defined by mould walls. Thus when a first mould chamber is indexed from the first position to the second position, a further mould chamber is indexed to the first position to take the place of the first mould chamber. When the further mould chamber is in the first position, the motor of the continuous rotary extrusion machine is enabled once more and supply of the extruded feedstock to the expansion zone is resumed. Subsequently, the first mould chamber is returned to the first position. In this way, the production cycle may be shortened.

It will be understood that if the former is sufficiently far advanced into the blank, withdrawn and the mould chamber is then indexed, a hollow cylinder of material will be formed from the blank within the mould chamber. Such a hollow cylinder may have utility as a cylinder liner, for an intemal combustion engine.

A modification of this method of manufacture will now be explained by reference to Figure 3 and Figure 4. Again, a supply of feedstock is generated by a continuous rotary extrusion machine 20 from a supply of powdered metal or similar. The feedstock is fed into a tooling chamber 22, corresponding to the tooling chamber 10 of Figures 1 and 2. In the modified apparatus the tooling chamber 22 is defined by a heated die 23, the internal walls 24 of a mould and a fixed back stop 25.

The supply of extruded feedstock to the tooling chamber is controlled in the same manner as that described with reference to Figures 1 and 2.

The mould chamber initially is located at a first position 26, and is then indexed in a direction transverse to the expansion chamber to shear through the extruded material. The mould chamber is indexed to a second position 27. At, or at a distance from, this second position 27, the blank of extruded material is worked by a vertical press to form the desired shape of the forged article.

The mould may be provided with an end wall, not shown, to be contiguous with the back stop 25.

Otherwise the mould, and the means of indexing the mould, may be at least substantially the same as described with reference to Figures 1 and 2.

Claims

1. A method of producing a series of individual forged articles from a feedstock produced on a continuous rotary extrusion machine from metal powder supplied thereto comprises repeating a cycle of steps comprising, in any appropriate sequence: i) extruding the feedstock into a tooling chamber initiatly to form a blank in a mould chamber comprising part of the cooling chamber, the mould chamber being at least partially defined by a mould, the mould chamber being moveable between a first position and a second position to separate the material in the mould chamber from the feedstock; ii) stopping extrusion of the feedstock; iii) moving the mould chamber from the first position to the second position; iv) with the mould chamber in the second position, ejecting the material from the mould chamber; v) forging the blank to produce an article; and vi) moving the then hollow mould chamber from the second position to the first position.

2. A method according to claim 1, in which the feedstock is extruded into a second mould chamber then in the first position, while the first mentioned mould chamber is in the second position.

3. A method according to claim 1 or claim 2 in which the sequence of the cycle of steps comprises: i) extruding the feedstock into a tooling chamber initially to form an extruded blank in a mould chamber at least partially defined by a mould, the mould chamber being moveable between a first position and a second position to separate the blank from the feedstock; ii) stopping extrusion of the feedstock; iii) moving the mould chamber from the first position to the second position; iv) with the mould chamber in the second position, ejecting the blank from the mould chamber; v) moving the then hollow mould chamber from the second position to the first position, and vi) forging the blank to produce an article.

4. A method according to claim 1 or claim 2 in which the sequence of the cycle of steps comprises: i) extruding the feedstock into a tooling chamber initially to form a blank in a mould chamber at least partially defined by a mould1 the mould chamber being moveable between a first position and a second position to separate the blank from the feedstock; ii) stopping extrusion of the feedstock; iii) moving the mould chamber from the first position to the second position; iv) forging the blank to produce an article; v) ejecting the article from the mould chamber; and vi) moving the then hollow mould chamber from the second position to the first position.

5. A method according to claim 1 of claim 2 in which the sequence of the cycle of steps comprises: i) extruding the feedstock into a tooling chamber initially to form a blank in a mould chamber at least partially defined by a mould, the mould chamber being moveable between a first position and a second position to separate the blarrk from the feedstock; ii) stopping extrusion of the feedstock; iii) forging the blank to produce an article, by advancing a former to penetrate the blank within the mould chamber to generate a profile; iv) withdrawing the former; v) moving the mould chamber from the first position to the second position; vi) ejecting the article from the mould chamber; and vii) moving the then hollow mould chamber from the second position to the first position.

6. Apparatus for the manufacture of a series of individual forged articles from extruded feedstock comprising a continuous rotary extrusion machine for the production of the feedstock from a metal powder supplied thereto; the apparatus including a tooling chamber at least partially defined by a heated die and a mould, and the tooling chamber including an expansion zone and a mould chamber partially defined by the walls of the mould, a blank to be formed in the mould chamber, and the mould chamber being moveable transversely to the expansion zone, indexing means to move the mould chamber transversely to the expansion zone between a first position and a second position; means to stop extrusion of the feedstock; means to eject material from the mould chamber when the mould chamber is in the second position; and means to forge the blank.

7. Apparatus as claimed in claim 6 including a second mould chamber which is in the first position when the first mentioned mould chamber is in the second position.

8. Apparatus as claimed in claim 6 or claim 7 in which the means to forge the blank is at a distance from the second position.

9. Apparatus as claimed in claim 6 or claim 7 in which the means to forge the blank is at the second position.

10. Apparatus as claimed in claim 6 or claim 7 in which the means to forge the blank comprises a former moveable between an advanced position within the mould when the mould chamber is in its first position, and a retracted position spaced from the mould.

11. Apparatus as claimed in any one of claims 6 to 10 in which the means to stop extrusion of the feedstock includes control means to detect a rise in current to a motor driving a moveable part of the continuous rotary extrusion means, and, in response to detecting such a current rise, is arranged to stop the supply of the metal powder to the continuous rotary extrusion machine.

12. Apparatus for the manufacture of a series of individual forged articles substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings, or the modification thereof as described herein with reference to Figures 3 and 4 of the accompanying drawings.

13. A method of producing a series of individual forged articles substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings, or the modification thereof as described herein with references to Figures 3 and 4 of the accompany drawings.