Metal deforming – By extruding through orifice – Indirect extrusion
Reexamination Certificate
2000-02-11
2001-04-10
Tolan, Ed (Department: 3725)
Metal deforming
By extruding through orifice
Indirect extrusion
C072S253100, C072S271000
Reexamination Certificate
active
06212929
ABSTRACT:
DESCRIPTION
The invention relates to an apparatus for the forming, in particular for the cold-forming, in this case in particular for the cold extrusion, of a workpiece, the apparatus comprising a die and a feeding device by means of which a relative motion between the workpiece and the die can be realized, as well as to a method for the forming, in particular for the cold-forming of a workpiece, wherein a relative motion between a workpiece and a die is produced by means of a feeding device.
Such apparatus and method are generally known and therefore do not have to be described in greater detail. The disadvantage of known apparatuses and methods are that high feed forces are required to achieve the desired cold-forming of the workpiece.
From U.S. Pat. No. 4,197,757, a method and an apparatus for cold-forming of a workpiece is known by means of which the latter can be transformed into the desired geometric configuration. For this, it is provided that the workpiece is inserted in a recess while the recess is open, that one end of the recess with the workpiece accommodated therein is closed and an anvil is arranged at the other end in order to form an annular space between anvil and the wall of the recess, that the annular space then is closed and a first pressure is exerted on a selected area of the workpiece in such a way that an extrusion of the workpiece starts via the anvil and the recess is filled. Afterwards, the volume of the annular space between the anvil and the wall of the recess, in which the workpiece is extruded, is increased while an essentially uniform second pressure, which is contrary to the direction of flow of the metal, is exerted on the workpiece in which case the magnitude of the second pressure is smaller than that of the first pressure whereby the metal essentially flows uniformly during the extrusion. The apparatus provided for carrying out the method has a mechanism with which the anvil can be moved back and forth.
The object of the present invention is to provide an improved apparatus and method such that a reduction of the feed forces required for the forming, in particular a cold-forming, of a workpiece is achieved.
This problem is solved by an apparatus according to the invention in that the apparatus has a frequency generating device working together with the feeding device by means of which the relative motion between workpiece and die caused by the feeding device can be modulated in such a way that after a forward stroke, in which at least one of the workpiece and the die is moved a first stroke length in the direction of feed, in a subsequent reverse stroke, a movement of at least one of the die and the workpiece by a second stroke length can be carried out in a direction contrary to the direction of feed.
Through the measures according to the invention, it is achieved in an advantageous way that the feed force which is required for the forming, in particular for the cold-forming, for example, a cold extrusion of a workpiece, and which is needed for the realization of a defined final forming of the workpiece, is considerably smaller than in a conventional apparatus. This does not only lead to that the energy required for the operation of the apparatus according to the invention is reduced and a clear saving in energy is achieved. The smaller forces occurring during the forming with the apparatus according to the invention allow also a simpler and therefore less expensive type of construction of the apparatus according to the invention whereby the production costs also are reduced. The “hammerlike” force impacting of the to-be-cold-formed workpiece by the intermittent, strokelike feed movement allows in an advantageous way a high-quality cold-forming with minimal effort and wear. Another advantage consists in that the workpiece is subject to only small axial forces so that buckling and deformation, also in the form of bulging, to a large extent are prevented.
Other advantageous, further developments of the invention are the subject-matter of the dependent claims.
REFERENCES:
patent: 3550417 (1970-12-01), McMaster
patent: 3572080 (1971-03-01), Alexoff et al.
patent: 3585832 (1971-06-01), Hinshaw et al.
patent: 3707866 (1973-01-01), Brauer
patent: 3818799 (1974-06-01), Hague
patent: 4131164 (1978-12-01), Hague et al.
patent: 1929558 (1970-12-01), None
patent: 1364019 (1994-03-01), None
Kasper Horst M.
Tolan Ed
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