Metal deforming – By use of non-deforming work-gripping clamp and relatively... – With interrelated clamp closer and tool mover
Reexamination Certificate
1999-05-18
2001-01-09
Crane, Daniel C. (Department: 3725)
Metal deforming
By use of non-deforming work-gripping clamp and relatively...
With interrelated clamp closer and tool mover
C072S370210, C029S560000, C029S897200
Reexamination Certificate
active
06170313
ABSTRACT:
TECHNICAL FIELD
This invention relates to a process by which it is possible to make a sharp-angled indentation on hollow tubes without removing any matrial, maintaining a constant thickness of tube and also without deforming the external diameter and conserving the fibre orientation of the metal.
In many industrial fields, it is necessary to make a series of indentations in tubes for adjustment purposes.
As a non-exhaustive illustration, such indentations are used in the automobile industry when making “frames” for adjustable head restraints for motor vehicles.
In order to make indentations in tubes, processes have already been proposed that involve machining and removing material, a technique which is difficult to apply in the case of hollow tubes, or that use a press, which leads to deformation (caving in) of the tubes, making further machining necessary, and which does not enable sharp-angled indentations to be produced.
The presence of sharp-angled indentations is essential in order to ensure catches are properly engaged and that positions can be adjusted.
Consequently, the “frames” of head restraints for motor vehicles are, as a general rule, currently made from non-tubular, solid cylindrical metal bars, which to a great extent increases their weight and their cost price.
OBJECTS OF THE INVENTION
The purpose of this invention is to resolve these problems by offering a process that makes it possible to make sharp-angled indentations on hollow tubes, without removing any material.
According to this invention, it has been possible, surprisingly, to achieve this objective not by means of a press as has previously been proposed, but by means of a riveting machine which in itself is a well-known machine, comprising a riveting head fitted to a spindle operating in conjunction with pressing devices and a fixed half-clamp.
SUMMARY OF THE INVENTION
The process used in this invention is characterised by the fact that the riveting head of a riveting machine of this type is replaced by a former adapted to the profile of the indentation to be made and in particular to its sharp angle. The tube on which indentations are to be made is inserted between the former and the fixed half-clamp and the pressing devices are activated, causing movement of the spindle, in order to allow indentations to be made in the tube.
Thus by radial deformation it is possible to obtain indentations of various shapes, without removing any material, and to maintain a sharp angle in the side engaged by the catch, without deforming the external diameter of the tube.
One of the most important characteristics of the invention is that the riveting machine is a riveting machine with an epicycloid mechanism and a spherical joint.
When such a machine is used, the indentation former is subjected to a complex movement that can be broken down into a translational movement and an orbital movement.
It has thus been possible to make indentations in tubes with a depth one-and-a-half times their thickness, without perforating the deformed part.
Another characteristic of the invention is that the spindle of the riveting machine is fitted with a holding-down clamp, the front part of which secures the tube in which indentations are to be made and holds it tightly against the fixed half-clamp.
Another characteristic of the invention is that rotation movement of the indentation former is prevented by means of a stabilising device.
There are no limits in terms of the maximum and minimum tube diameter that can be handled by the process. The depth and the surface area to be obtained determine the power of the riveting machine.
By way of example, tests have been carried out on steel tubes with an external diameter of 11.70 mm and an internal diameter of 7.80 mm. A force of 500 daN was required in order to obtain indentations 2 mm in depth with an ware of 50 mm
2
.
The invention also relates to a hollow tube produced by means of the process described above.
Such a tube is characterised by the fact that it has sharp-angled indentations which have been made without removing material, maintaining constant tube thickness.
REFERENCES:
patent: 1615724 (1927-01-01), Pierce
patent: 2491119 (1949-12-01), Lewis
patent: 3765079 (1973-10-01), Pfefferle
patent: 4574610 (1986-03-01), Hull
patent: 4582259 (1986-04-01), Hoover
patent: 4679850 (1987-07-01), JBianchi et al.
patent: 297 14 315 [0 U (1998-01-01), None
patent: 2 612 096 A1 (1987-03-01), None
Garconnet Claude
Garconnet Dominique
Vasseur Jean-Pierre
Crane Daniel C.
Etablissements Garconnet
Hughes & Schacht, P.S.
Schacht Michael R.
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