Metal deforming – By relatively movable offset tool-faces – Multi-point tool-couple
Patent
1984-05-09
1986-08-05
Larson, Lowell A.
Metal deforming
By relatively movable offset tool-faces
Multi-point tool-couple
72396, 72414, B21D 1302
Patent
active
046035729
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for bending plates having a corrugated profile, comprising a pair of press beams which are positioned parallel one relative to the other and are mounted to be moved towards and away from each other in transversal direction, said one or lower press beam having at its upper edge a series of alternating recesses and extensions which correspond with the exterior valley profile and interior crest profile respectively of the plate to be bent, while said second or upper press beam has a series of alternating extensions and recesses which correspond with the interior valley profile and the exterior crest profile respectively, and in which on the sidewalls of the recesses in said upper press beam--adjacent the junction of said sidewalls and the bottoms of said recesses--a protuberance is provided adapted to amply engage into a corresponding cut-out in the sidewall of the underlying extension of the lower press beam when the two press beams are brought together, said lower press beam having a punch portion at its upper face extending in the longitudinal direction of said face and adapted to be amply caught in a corresponding longitudinal groove in the lower faces of the recesses of the upper press beam.
More particularly the invention relates to the bending of corrugated sheets, with which the alternating valleys and crests are trapezoide, like a metal coffer dam. Such plates, which are often referred to as plates having a coffer dam profile, are used on a large scale for roofing and cladding purposes.
PCT application No. WO 80/00932 describes a device of the kind above referred to for bending such plates about an axis extending transversally to the valleys and crests, in which by means of said punch portion a series of aligned ribs, extending transversally to the crests and valleys, is impressed from beneath, i.e. towards the crests, into the bottoms of the valleys, while the protuberances on the side faces of the recesses in the operative upper face impress corresponding bulges into the sidewalls of the valleys of the plate in the region adjacent the ends of the ribs in the bottoms of said valleys. In such a way in fact a slight fold (of e.g. 5-10 degrees) is effected in the corrugated feed. By applying a number of such folds along a number of successive parallel folding lines it is possible to bend such a corrugated plate through any desired angle and according to a bending radius whicy may be varied within wide limits.
In practice a disadvantage of this well-known device is found in that there appears a high degree of irregularity with respect to the shape and positioning of the bulges impressed into the sidewalls of the valleys. This irregularity results in a variation of the plate width in the bending zone, while there may be large differences between the ultimate bending angle and the expected bending angle.
Tests have led to the insight, that during the initial phase of the bending procedure, in which the bulges are impressed, the plate is insufficiently supported against undesired movements. During this initial phase the plate is in fact only supported by the relatively narrow punch portion, so that uncontrolled swinging movements may occur about this punch portion.
According to the invention and making use of said insight the above disadvantage is overcome in that the punch portion is movably mounted between an inoperative position, in which said punch portion has its operative upper edge sunk into a groove extending across all of said recesses of the lower press beam, and an operative position, in which the said punch portion has its operative upper edge projecting through said groove upwards beyond the bottoms of the recesses in the lower press beam. Due to the measure according to the invention a device has been obtained, with which the bending peocedure is taking place in two distinct stages, i.e. a first stage, in which the bulges are formed, and a second stage, in which the ribs are formed. During the first stage the punch portion is taking its inoperative retracted
REFERENCES:
patent: 1556611 (1925-10-01), Klocke
patent: 2033667 (1936-03-01), Almdale
patent: 4347726 (1982-09-01), Naslund
Van Breukelen Jacobus A. T.
Westerveld Theodorus
Dupral B.V.
Larson Lowell A.
Showalter Robert
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