GB428444A - Improvements in die head devices for screw machines - Google Patents

Abstract

428,444. Screwing die-heads. STENMAN, P. L., 32, Ostermalmsgatan, Stockholm. Aug. 4, 1933, No. 22007. Convention date, Aug. 4, 1932. [Class 83 (iii)] In a screw-cutting die-head, particularly designed for making wood-screws, the chasers are controlled by two independently rotatable members which are actuated during the cutting operation so as to move the chasers rapidly to and from the axis of the head and to impart the desired form and depth to the thread and cut threads at the conical point of the blank. In one construction, the head 11, Fig. 3, has two independently rotatable rings 6, 7 mounted thereon, the former being attached to the chaser carriers 2 by pivots 3 and the latter by slots and pins 4. The chasers 1 are inclined to the axis of the head as shown to obtain the correct cutting position in relation to the pitch of the thread and to facilitate the escape of cuttings. In a modification the pivots 3 are arranged on the outer ring 7 and the pins and slots 4 on the inner ring 6. In a further modification the chasers 1, Figs. 6 and 8, are eccentrically mounted in radial pivots 3 which may be rocked about their axes by levers 8 carrying ball-ended pins 4 engaging the rotatable ring 7, whilst the pivots 3 are themselves carried by the rotatable ring 6. The body of the head is not shown in Fig. 6. In another modification the chasers 1, Fig. 9, are mounted in carriers 2 attached to the radial pivots 3 on the ring 6, the levers 8 on the pivots 3 being connected to the ring 7 by ball-ended pins 4. The members 6 and 7 may be annular or may be composed of several parts attached to each other and are rotated during the threading operation by arms, links, &c., of known construction. In order to compensate for the different lengths of travel of the chasers of a head in forming wood screws, the pivots 3 or the chasers are arranged at different distances from the head axis, and alternatively or in addition, the pins 4 may be arranged eccentrically with regard to the head axis.