Metal deforming – By deflecting successively-presented portions of work during... – By use of work-contacting wiper and moving – work-holding form
Patent
1988-03-18
1990-07-17
Combs, E. Michael
Metal deforming
By deflecting successively-presented portions of work during...
By use of work-contacting wiper and moving, work-holding form
72153, 72155, B21D 704
Patent
active
049413384
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for cold bending pretensioned ferrous and non-ferrous metal sections.
A known apparatus for bending metal sections is disclosed in the German patent No. DE-34 04 641A1 from the same inventor. It is characteristic of this apparatus that the initially straight metal section is adjustably tensioned and that then the tensioned metal section is subjected to rotary bending.
The rotary bending is achieved by pressing a feed rail die with adjustable force against the underside of the metal section, whereby the rotating tool attached to at least one end of the metal section exerted a rotational movement, i.e., a winding movement, and that the tensioned metal section wound around the external perimeter.
With this known apparatus, it was possible for the first time to cold form large and small volume, thin and thick walled sections, with the possibility of bending sections of any shape with a high degree of accuracy in one plane. The basis for the known apparatus is the knowledge that the pretensioning constantly applied during forming equals the shear stress generated in the section during bending and assures a nondeforming bend. An additional advantage is achieved by means of the die rail pressed against the underside of the section during forming in that the coarse grain structure obtained by exceeding the elastic limit of the billet during forming is compressed back to fine grain structure. The forming is thus a type of cold forging which contributes to a strengthening of the billet material during forming by bending. If in fact the coarse structure were retained, modifications of the properties of the material would be inevitable, such as, for example, increased tendency toward brittle fractures. Thus the structural conversion contributes to a reduction in the hardening of the material.
With the known apparatus it was, however, not possible to bend such sections on just any spatial axis; it was also not possible to produce three-dimensionally bent sections.
Furthermore, it was not possible with the known apparatus to form extrusion sections with an undercut groove or a hollow section without deformation of the groove or the hollow section after successful bending.
SUMMARY OF THE INVENTION
Therefore, the underlying object the invention is to enhance a device of the type mentioned in the beginning in such a way that sections of steel and nonferrous metals may be produced in any curved shape whatsoever, particularly cornu spirals or transition curves (i.e., a spiral curve with a continuously decreasing radius), rationally and with reliable shape, without deforming the particular cross-section of the section.
To meet the stated objective, the apparatus is distinguished by the fact that to achieve three-dimensional forming of the metal section, the bending tool exerts a controlled movement in all spatial axes and the section is pressed against the bending tool with a backlash-free guide system at least in the forming region and is guided by positive engagement.
An essential element of the present invention is thus that the bending tool exerts a controlled three-dimensional movement on all three spatial axes and that, at least in the forming region of the section, there is a backlash-free guide system oh the external side of the section, which engages the section positively and presses it against the bending tool. Thus, undesirable deformations of the cross-section of the metal section during bending are avoided. Thus, for the first time, thin and thick walled, large and small extruded, drawn, bent, or rolled metal sections or even hollow sections of steel or nonferrous metal sections can be bent in any spatial direction whatsoever without deformation. An advantageous embodiment of the present invention is the production of guide rail systems from aluminum sections. Such guide rail systems are used in motor vehicles to provide an aluminum extrusion section which is bent in several planes and sometimes also twisted with a guide slit along the groove
REFERENCES:
patent: 2713376 (1955-07-01), Bath
patent: 2806506 (1957-09-01), Yurka
patent: 2945529 (1960-07-01), Hein
patent: 2988127 (1961-06-01), Gray
patent: 3155139 (1964-11-01), Hautau
patent: 4481803 (1984-11-01), Dieser
Combs E. Michael
Spath GmbH & Co. KG
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