GB586402A - Improved method of and means for bending sheet metal - Google Patents

Abstract

586,402. Angular bending. HOWEY, W. L. Dec. 14, 1944, No. 25099. [Class 83 (iv)] Dies and formers.-In bending sheet metal progressively by feeding it between a pair of press dies, one of which is stationary and the other is given a vibration of small amplitude and high frequency perpendicular to the direction in which the sheet is fed between the dies, the dies each consist of relatively fixed portions provided with tapered internal or external surfaces applying both vertical and lateral pressure to the work and shaped to produce semi-open and completely closed sections. Sheets are thus provided with marginal strips of semicircular, circular, oval or other section, or converted into split tubes or bent to form rectangular channels or other sections for making metal doors, cabinets and other furniture. In making a circular beaded edge, the upper movable die, which is carried by a bolster suspended on connecting rods driven by eccentrics on a power-driven rotary shaft, so as to give a stroke of <1>/16 inch at a frequency of 1500 reciprocations per minute, is provided on the forward portion of one edge with a surface which is tapered and has a semicircular rib a, Figs. 2 and 7, running lengthwise thereof to co-operate with a semicircular groove d, Fig. 3, of uniform depth'running the full length. of the lower die so as progressively to produce an initial bend of semicircular section with an upstanding extension as shown in Fig. 10. One wall of the groove is wedge shaped at d<1> to co-operate with the rib. The final portion of the die consists of a downwardly-tapered tunnel c, Figs. 2 and 6, of inverted U-shape which co-operates with the groove in the lower die to convert the edge to circular form. Between the two portions of the upper die is a recess b co-operating with a mandrel e, Figs. 3 and 12, pivoted on a stud g on the lower die so as to adjust itself to irregularities, the mandrel having an inverted U-shaped part h extending over the groove d to engage the upstanding portion of the strip. The mandrel is provided with a rod k of circular section, tapering to a diameter equal to the internal diameter of the circular section to be formed. The sheet is fed by hand or automatically between the dies. In making flanged channel sections in three successive but continuous stages, the upper die is provided on its entrance end with a central mallet m, Fig. 15, coacting with spaced wedge strips n, Fig. 16, on each side of a central groove p in the lower die to bend the strip into the section shown in Fig. 18. In the intermediate stage, the upper die has a central mandrel r, Fig. 19, and two converging die faces s co-operating with the groove p to close together the upstanding flanges and bend them progressively into the form shown in Fig. 21. Finally, diverging die faces t, Fig. 24, continue the handrel of the upper die to coact with the groove p and a central gap u between a pair of flat plates v in the lower die to bend over the flanges as indicated in Fig. 25.