Metal deforming – By deflecting successively-presented portions of work during... – By use of deflectors arranged to bend work longitudinally of...
Patent
1984-02-21
1986-10-28
Crane, Daniel C.
Metal deforming
By deflecting successively-presented portions of work during...
By use of deflectors arranged to bend work longitudinally of...
72170, 72168, B21D 508
Patent
active
046191313
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a process of bending sheet metal having a sectional shape which is continuous in one direction, such as trapezium-section or rectangular-section sheet metal elements.
The bending of sheet metal sections, particularly so-called trapezium-section sheet metal elements, bent about axes at right angles to the height of the section, is hardly possible at all or involves a high expenditure. This is due to the fact that the bending gives rise to tensile and compressive stresses and the sheet metal elements to be bent resist tensile stresses but do not resist substantial compressive stresses. For instance, when it is attempted to bend a trapezium-section sheet metal element in the conventional manner, the sheet metal element will buckle in the portion subjected to compressive stresses and the size of such buckled portions will be within tolerable limits only when the bending radius exceeds about 25 mm.
On the other hand there is a strong demand for sheet metal elements which are bent with radii that are much less than 25 meters, for instance for roof trusses, where radii of bend of 5 to 10 meters or even smaller radii of bend are desired.
In a known process of bending trapezium-section sheet metal elements a press is used to emboss spaced apart depressions into the sheet metal element, which depressions extend transversely to the height of the section. Whereas the trapezium-section sheet element can actually be bent in this manner, the process has severe disadvantages. On the one hand, the process is very slow and expensive because it is intermittent rather than continuous. On the other hand, the sheet metal element bent in accordance with the known process can hardly be stressed because owing to the transverse depressions it can easily be folded together like the bellows of an accordion.
It is an object of the invention to provide for the bending of sheet metal sections, particularly trapezium-section sheet metal elements, a process which can be carried out quickly and simply and results in bent sheet metal elements of high quality. Specifically, the bending should not reduce the strength of the sheet metal elements.
In a process of the kind described first hereinbefore, that object can be accomplished according to the invention in that longitudinal beads are formed or existing beads are reinforced in the sheet metal element as it is bent at least in the region in which the bending results in an upsetting of material, i.e., in the region in which the sheet metal element is subjected to compressive stress.
In this way, sheet metal sections can be bent in a surprisingly simple manner and at high velocity. The sheet metal elements have the same strength before and after the bending.
It is pointed out at this juncture that unbent planar trapezoidal-section sheet metal elements having longitudinal beads are known in the art. Such longitudinal beads in the inner and outer chords serve to increase the moment of inertia and moment of resistance. The process according to the invention may be used to bend also sheet metal elements which have been provided with beads before; for that purpose, such beads may be en-larged or additional, new beads may be formed.
When it is desired to bend trapezium-section sheet metal elements consisting of inner and outer booms with respect to the axis of curvature, and webs connecting said booms, at least one bead is formed in each of the inner booms and of the webs. As compressive stresses arise during the bending operation only in the inner booms and the inner web portions, it will be sufficient to provide beads in these regions.
In many cases, however, it is desirable for reasons of manufacturing technology and of economy to provide beads at the centre of each of the outer and inner booms and in each web adjacent to the center plane of the sheet metal element.
The process according to the invention can be carried out to special advantage by an apparatus comprising a driven pair of rolls, which comprises a stationary roll and a roll which is adjustable to define a
REFERENCES:
patent: 1354951 (1920-10-01), Buhtz
patent: 1793351 (1931-02-01), Bell
patent: 2093933 (1937-09-01), Sinclair
patent: 2279197 (1942-04-01), Hoell
patent: 2335028 (1943-11-01), Rose et al.
patent: 3051214 (1962-08-01), Rutten
patent: 3073021 (1963-01-01), Goodwill et al.
patent: 3150707 (1964-09-01), Howell
patent: 3610011 (1971-10-01), Valentine
patent: 4154077 (1979-05-01), Cotter
patent: 4228672 (1980-10-01), Gale et al.
Crane Daniel C.
Schaffer Murray
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