Metal deforming – With temperature modification of tool or of specified...
Reexamination Certificate
2000-09-27
2001-12-04
Tolan, Ed (Department: 3725)
Metal deforming
With temperature modification of tool or of specified...
C072S342940, C072S354600, C072S364000, C072S370100, C072S377000
Reexamination Certificate
active
06324883
ABSTRACT:
The invention relates to a method for formation of an enlarged end portion of a bar by upset forging. The invention further relates to a tool for implementing the method.
From “Handbuch des Schmiedes”, Hans W. Haller, Carl Hanser Verlag 1971, pages 462, 463, it is known that a bar can be secured in the passage of the form part and that the entire portion which has to be upset extends into the cavity, whereby the bar has a full, circular cross section and the enlarged end portion has a larger diameter than the bar.
The volume of the enlarged end portion hereby corresponds to the volume of the bar portion which was initially located in the cavity. If the enlarged end portion is going to be large, the non-upset end portion of the bar must be correspondingly long, and particularly if the length of the non-upset end portion exceeds a length which is approximately six times diameter of the bar, there is a risk that during the initial upsetting, i.e. during the influence of a central buckling load which is exerted by the above-mentioned wall or wall part, the bar portion will be bent outwards and come into contact with the cavity's side wall. It is possible that the bar portion may be bent in the cavity. As the upsetting continues, therefore, folded bar portions may come into contact with one another without these sides being completely joined. The completed, enlarged bar portion may consequently be very unhomogeneous with pronounced fault lines or surfaces. If this bar is a part of a supporting structure, it will be understood that the occurrence of such weakened portions can be unacceptable and that the use of such a method may lead to a large percentage of rejected products during a production.
The object of the invention is to provide a method and a tool of the above-mentioned type which is not encumbered with this disadvantage.
The characteristic of the method according to the invention is presented by the characteristic features indicated in the claims.
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Urals Pipe Ind. Res., “Thickened-End Tube Making Process—Involves Preheating Front End of Blank Out of Contact with Stop Before Applying Axial Force to Rear End”, Derwent Abstract No. 90-303344/40 of SU 1547932, Derwent Publications Ltd., London, (1990).
Pipe Ind. Res. Inst., “Material Local Thickening of Rod or Pipe Type of Components—Involves Heating of Deformation Zone, Twisting and Application of Axial Compression Forces”, Derwent Abstract No 92-329473/40 of SU 1697967, Derwent Publications Ltd., London, (1991).
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kongsberg Automotive ASA
Tolan Ed
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