Metal deforming – By application of fluent medium – or energy field – Using fixed die
Patent
1992-09-23
1994-04-19
Jones, David
Metal deforming
By application of fluent medium, or energy field
Using fixed die
72 61, 294211, B21D 3920, B21D 2602
Patent
active
053035704
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method of hydrostatically deforming hollow bodies of cold-shapable material inside a cavity of a die where pressurized fluid is fed from outside into the hollow body so as to force a wall of the hollow body against an internal surface of the die in a deformation region with the hollow body being held outside the deformation region by at least one holding region.
BACKGROUND OF THE INVENTION
In the above-described type of process (see Industrie-Anzeiger No. 20 of 08 Mar. 1984/ 10 yr. pages 16 and 17) tubular hollow parts of cold-deformable metal, for instance 16 MnCr 5, are deformed by the application of high internal hydrostatic pressure. Added to the high hydrostatic internal pressure there is a particular axial pressure that is effective on the end surfaces. This axial pressure and the simultaneous effect of the internal pressure have the result that the wall of the hollow body conforms to the surface of the mold or die.
In practice a straight tube is positioned in the separation plane between upper and lower die halves and the die is closed. Between the upper and lower die halves there is however sufficient space for two diametrally opposite coaxial arranged horizontal rams whose free end faces confront and engage the tube to be deformed The deformation takes place by feeding pressurized fluid into the interior of the tube while simultaneously exerting axial pressure by pushing the two rams toward each other.
With the known hydrostatic deformation it is possible to produce parts with uniform shape around their circumference, parts with sectoral deformation, and also parts with uniform and sectoral deformation combined.
The advantage of hollow parts produced in this manner is primarily that, as for instance with chill casting, undercut internal spaces can be produced which could not be produced by machining or could only be done with complicated tools (for instance by spark erosion). In addition the known hollow parts--in contrast to hollow parts produced by machining--are relatively light and as a result of the cold forming from the deforming when the fibers are properly oriented are particularly strong like forged goods.
Nonetheless the known internal high-pressure deformation has been found disadvantageous because a certain minimum thickness of the wall of the hollow body cannot be exceeded. This is mainly due to the fact that the tubular bodies must be made stiff enough to resist a relatively high pressure exerted on their ends, which can only be achieved with a certain minimum wall thickness.
In addition the known internal high-pressure deformation can only be used with parts where the axial force coincides exactly to the centerline of the tube and of the die. In this manner it is possible to produce substantial lateral sectoral deformations for producing, for example, crosspieces or T-pieces. In this case the longitudinal axis extends in accordance with the die's sectoral produced outward deformation transversely to the common force lines of the rams and of the tube (see Industrie-Anzeiger op. cit. page 17, FIGS. 4 and 8).
With the known internal high-pressure deformation it is possible to produce a certain number of shapes which however always lie within the framework of common lines of force of the rams and the tube to be deformed, thus for a straight basic shape.
OBJECTS OF THE INVENTION
Starting from the above-described known device (see Industrie-Anzeiger op. cit.), it is an object of this invention to change the known method to permit thin-walled and if necessary nonstraight hollow bodies to be deformed into more complex shapes than is possible with the known method.
SUMMARY OF THE INVENTION
This object is attained according to the invention in that the hollow body is floatingly held at each holding region without axial forces and the hollow-body wall is only moved by liquid pressure relative to the die, in particular drawn into same.
Whereas with the deformation process of the known method (see Industrie-Anzeiger op. cit.) the moveme
REFERENCES:
patent: 1542983 (1925-06-01), Bergmann, Jr.
patent: 3072085 (1963-01-01), Landis
patent: 4467630 (1984-08-01), Kelly
patent: 4928509 (1990-05-01), Nakamura
patent: 4951492 (1990-08-01), Vogt
patent: 5097689 (1992-03-01), Pietrobon
Industrie-Anzeiger No. 20 of Mar. 8, 1984, Year 10, pp. 16, 17.
Dubno Herbert
HDE Metallwerk GmbH
Jones David
Wilford Andrew
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