Metal deforming – With exposure of work to gas – vapor – mist – or modified...
Patent
1996-08-08
1998-07-21
Larson, Lowell A.
Metal deforming
With exposure of work to gas, vapor, mist, or modified...
72262, B21B 900
Patent
active
057821208
DESCRIPTION:
BRIEF SUMMARY
This invention relates to apparatus for continuously extruding metal. In particular the invention relates to a CONFORM machine.
British Patent Specification 1370894 describes a Conform machine. The machine basically comprises a rotatable wheel having an endless groove in its peripheral wall and a fixed shoe structure overlying the groove along part of its length to define a passageway therewith. The shoe member mounts a tooling assembly including an abutment which project into the groove to substantially close off the passageway and an extrusion die structure which extends out from the passageway at or upstream of the abutment. In use, a metal feedstock, such as copper or aluminiun, and conveniently in the form of a rod is fed into tile non-closed end of the passageway. The feedstock is drawn continuously by the rotating wheel along the passageway where it is heated by frictional engagement with the walls of the passageway. The metal impinges against the abutment and it leaves the passageway through the extrusion die structure in the form of a continuously extruded product.
It will be appreciated that when the metal from the feedstock flows through the extrusion die structure, some of the surface parts or the feedstock before deformation will be present inside the extruded product. Aluminiumn and copper readily undergo surface oxidation and if oxide contaminants on the feedback become entrained within the extruded product this can reduce the formability of the product and may cause blister defects on the surface of the product. Generally, the inclusion of oxide contaminants may make the product unacceptable to some potential customers.
An attempt to overcome this difficulty is described in EP-B-0074692. This specification discloses a conform machine for extruding non-ferrous metal feedstock and which is in combination with apparatus for continuously pre-treating the feedstock immediately before it enters the Conform machine. The pre-treatment comprises spraying the feedstock with a liquid deoxidation and cleaning agent. This agent removes the surface oxidation coating on the feedstock and the feedstock is subsequently rinsed and dried before it enters the Conform machine.
Since, the feedstock metal, e.g. copper and aluminium, is prone to oxidation it readily oxidises during the time it is within the Conform machine before it passes through the extrusion die. Thus even if the feedstock is thoroughly cleaned to remove surface contaminant before it enters the conform machine, additional surface oxidation can occur in the machine before the feedstock is extruded and some of this oxide can be contained within the extruded product.
GD-B-2241660 addresses this problem and it is stated in the specification that a reducing gaseous environment can be arranged in and about the passageway which receives the feedstock in a conform machine. To this end a jet or jets are arranged to direct reducing gas into the groove immediately before the introduction of the feedstock. By this procedure, oxidation of the feedstock in the machine is almost entirely eliminated.
During the operation of the Conform machine a small amount of metal is extruded between the abutment and the walls of the groove. This metal is made up of two parts, `flash` or metal which is ejected from the groove and a film of metal which forms a tire within the wheel groove. Both the flash and the tire are easily oxidised and will contaminate new clean feedstock entering the groove. As much as possible of the flash is usually removed by a scraper placed down stream of the abutment and before the flash re-enters the groove. However, even with efficient scraper operation some small pieces of flash will remain in the groove. The tire is not removed by the scraper operation. Both the remaining pieces of oxidised flash and the oxidized tire in the groove will contaminate the clean feedstock entering into the groove.
This problem of oxidised flash remaining in the groove has also been considered in GB-B-2241660 and to overcome the problem it is promised to arrange a
REFERENCES:
patent: 4316373 (1982-02-01), Zilges et al.
patent: 5133126 (1992-07-01), Matsuoka
Holton Machinery Ltd.
Larson Lowell A.
Tolan Ed
LandOfFree
Continuous extrusion does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous extrusion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous extrusion will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1638009