Patent GB-1427507-A (GB)
Title: Fastener feed apparatus
IPC: B25B23/04
Filed: 1974-11-04
Abstract: 1427507 Fastener feeding and driving DUO-FAST CORP 4 Nov 1974 [5 Nov 1973] 47553/74 Heading B3N [Also in Division B8] In a fastener feed apparatus for attachment to a tool 32, Fig. 1, having a rotary drive member, e.g. screwdriving bit 46, Fig. 12, for driving threaded fasteners 34, there is a base member 48 adapted to be mounted on the tool (as shown, at the chuck) a workpieceengaging nose assembly 50 mounted for reciprocal movement toward the base member as the tool is pressed towards the workpiece and a return spring 114 compressed between the base member and the nose assembly. The nose assembly defines a drive path 122 (in nose block 100) for movement of the drive member 46 therethrough, Fig. 12, in a drive stroke, and a feed path 124, intersecting path 122, for supporting a fastener strip 36. A pawl mechanism, comprising a pawl 174, is engageable with a series of engagement structures, e.g. holes 68, Fig. 1, in the strip and is mounted on the nose assembly for movement along the feed path between a cocked position, Fig. 16, and a home position, Fig. 14, wherein a fastener is aligned with the drive member 46, during which movement the fastener strip is fed. A pawl spring 198 biases the pawl towards the home position and abutment means 207 on the nose assembly and engaged by lever 176 of the pawl mechanism defines the home position. Linkage, 178 moves the pawl mechanism to the cocked position under relative movement of the nose assembly toward the base and retains the mechanism in this position by overcentring but is released during movement of the nose assembly away from the base to allow the pawl to feed the strip. In the first embodiment (Figs. 1-18) the nose block 100 slides in guides 104, 106 provided by a slide member 102, Fig. 12, fixed to base 48 which is clamped to the tool. The feed path 124 is additionally defined by profiled end 142- 154 of a plate 126 whose other end 138 has a serrated edge 170 which co-operates with that of an adjustable plate 160 which determines the length of drive stroke. The pawl 174 has a cam portion 206 which rides on the strip when moving from the home position to the cocked position so as to prevent reverse movement of the strip and this action is assisted by loosely mounting the pawl 176 at the pivot 182 to allow slight axial movement and by the provision of an abutment 208 in the nose-assembly front face which is engaged by the fastenersupporting side tabs 66 of the strip 36 which are deflected outwardly when the drive member 46 forces the fastener outwardly (Fig. 17, not shown). In the second embodiment (Figs. 19-28, not shown) nose assembly (304) slides on a member (328) forming an integral extension of clutch housing (310) attached to the housing 40 of the tool. The pawl mechanism comprises a pivoted lever (376) spring-loaded and mounted on a pivot pin (388) which allows slight axial movement as before. The lever is operated by engagement of a foot plate (392) thereon with an adjustable stop screw (394) mounted in base (302). In the third embodiment (Figs. 28-36) the pawl 473, Fig. 33, is mounted on a leaf spring 484 fixed at one end to a slide 474 which is slidable in a guide in the nose assembly 404 so as to reciprocate between the cocked position, Fig. 36, and the home position, Fig. 28, under the control of a spring loaded toggle linkage 476 having a lost-motion connection 478. The nose assembly slides, by means of screws (442) on plate (430) having slots (440). Retraction is limited by adjustable stop 414, 516. The lost motion connection 478 and that, 180, in the first embodiment are provided to ensure that there are adequate dwell periods in the cycle of operation. The fastener strip 36 may be drawn from a rotatable magazine 72, Fig. 1, mounted on the base. To ensure optimum running conditions the strip is twisted as shown.