Metal deforming – By relatively movable offset tool-faces – Multi-point tool-couple
Patent
1980-07-03
1982-09-07
Crosby, Gene
Metal deforming
By relatively movable offset tool-faces
Multi-point tool-couple
72389, 72412, B21D 3710
Patent
active
043477267
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of bending a sheet-metal section, which includes alternating longitudinal ridges and troughs, and the lateral portions of which also are the lateral portions of the ridges, about an axis, which extends perpendicularly to the longitudinal direction of the ridges and troughs and is in parallel with the plane of the sheet. The invention also relates to a device for carrying out the method.
It is previously known at the bending of such sectional or corrugated sheet about an axis extending perpendicularly to the corrugations and in parallel with the plane of the sheet to form in the corrugations, which with their tops are located closest to said axis, strip-shaped protrusions in the direction of the axis which project from one and the same side of the sheet, in such a manner, that each such protrusion extends at least partially over the sides of a corrugation and the intermediate portion uniting the sides, and the protrusions are given such a shape that the sheet shrinks more closely to the axis than farther away therefrom. By this way of bending a sectional sheet an accumulation of material is obtained in the transistion area between the side and the intermediate portion of a corrugation, which accumulation renders it impossible to bend a sectional sheet provided with a surface-covering coat without damaging the coat in one way of the other. It is not possible, either, by said known bending method to bring about a bend with a radius below 750 mm, which reduces substantially the applicability of this bending method.
It is further known to bend a sheet-metal section about an axis, which extends perpendicularly to the longitudinal direction of the corrugation and in parallel with the plane of the sheet, by a method, according to which impressions are made in radial direction from the axis only in those portions of the corrugations of the sheet which face toward the said axis. Said impressions are made in consecutive steps until the desired bending angle has been obtained. By this known method it is possible, contrary to said firstmentioned bending method, to bend also a sectional sheet, which is provided on one and/or the other side with a surface-covering coat, without damaging the coat on either side, provided that the sheet at the moment when the impressions are being made is not clamped on either side of the place of impression, but can move freely relative thereto. Even when the sheet is clamped only on one side of the place of impression, the lastmentioned method of bending a sheet-metal section involves a certain risk, that the sheet in certain parts is subjected to stretching, whereby a possible surface coat will be damaged and also the bending result will be deteriorated, i.e. the bending or deflection line will be more or less discontinuous.
The present invention, therefore, has the object to overcome the disadvantages involed with the lastmentioned method of bending sheet-metal sections, especially when it concerns the bending of clamped sheet metal, and at the same time to bring about a method and a device, which render it possible to bend sectional sheets with a radius, which is substantially smaller than heretofore possible, without damaging the sheet even when it is surace-coated. This object is achieved in that the method and the device according to the present invention have been given the characterizing features defined in the attached claims.
The invention is described in greater detail in the following, with reference to the accompanying drawings, in which
FIG. 1 is a section of a bending tool for bending a trapezoid sectional metal sheet according to the invention, shown in a schematic way,
FIG. 2 is a section along the line II--II in FIG. 1 through the lower portion of the bending tool formed as a pressing bar,
FIG. 3 is an end view of a bending die comprised in the upper portion of the bending tool and acting as a dolly member,
FIG. 4 is a lateral view of the bending die shown in FIG. 3,
FIGS. 5 and 6 are an end view and, respectively, a lateral view of an
REFERENCES:
patent: 1434068 (1922-10-01), Schlafly
patent: 1880479 (1932-10-01), Ragsdale
patent: 2199377 (1940-04-01), Tangerman
patent: 3499308 (1970-03-01), Ford
patent: 3874214 (1975-04-01), Racicot
patent: 4081987 (1978-04-01), Hall
patent: 4138875 (1979-02-01), Hooper
Crosby Gene
Groko Maskin AB
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