Patent GB-820001-A (GB)
Title: Improvements in or relating to apparatus for driving screws
Inventor: AUSTIN LEONARD EDMOND
IPC: B25B23/06
Filed: 1955-08-30
Abstract: 820,001. Screwing-up screws &c. ILLINOIS TOOL WORKS. Aug. 30, 1955, No. 24869/55. Class 83 (3). [Also in Groups XVII, XIX and XXX] A portable power-operated screw-driver comprises a stationary magazine 72, and a mechanism for positively feeding screws from the magazine into a position to be driven by a motor-actuated driving member 40. The pneumatic vane-type motor 32 is controlled by a plunger 38, and rotates the bit 40 through an overload release torque clutch. The end of the bit is shaped to fit the screw-head. Each screw is delivered in turn through a recess formed in a split sleeve 42 secured in a sleeve 48 sliding on the tool barrel 52. The halves of the sleeve 48 are held together by a coil spring 54 and leaf springs 56, and have bevelled internal ends 68 so that as a screw is forced downwardly it can move the sleeve halves apart. The screws are contained in a sliding T-section magazine 72 supported on the tool by a fixed bracket 80 and a bracket 88 on the sleeve 48. Downward movement of the magazine is limited by a screw 182 thereon engaging the bracket 80. An operating-handle 94 which controls the plunger 38 through a sliding pin 104, also actuates a rod 108 having an end passing through a slot in the bracket 88. Thus, when the handle 94 is pressed to start the tool, the sleeve 88 is drawn upwardly. The screws are urged downwardly in the magazine by an arm 126 pivoted on a slide 132 attached to a coilspring 152. The screws are allowed to escape one-at-a-time by a finger 156 pivoted to a bellcrank 172 which is itself pivoted to the sleeve 48, and has one end slidably anchored to the tool body by a rod 174. As the sleeve 48 is moved upwardly, the finger 156 is pulled back to engage behind the next screw. When the sleeve 48 returns to its initial position, the screw is snapped into the recess in the sleeve 42. A device for re-filling the magazine 72 comprises a hopper 194, Fig. 11, a slotted tumbler-drum 196 rotated through a slipping safety clutch 232, and a delivery shoot 250 closed by a pawl 274. The pawl 274 is connected by a rod 268 to an adjustable second pawl 284 lying clear of the screws. The two pawls embrace that number of screws which are necessary to fill a magazine 72. When the tool 30 is brought up to the refilling device, it pushes the rod 268 to release the lower pawl and engage the upper pawl, so that the requisite number of screws slides down into the magazine 72. Instead of refilling a magazine, the magazine may have a detachable portion 344, Fig. 16, which is retained in position by a releasable catch 326. The lower ends of the fixed part of this magazine have adjustable delivery ends 310. In another method of filling the magazine, the screws are contained in a cartridge 382, Fig. 21, the ends 388 of which are sprung inwardly to prevent the screws falling out. The cartridge is filled from a shoot which has spreader fingers engaging the ends 388. Similar spreader fingers are provided on the magazine on the tool to allow the screws to be transferred. Another device for filling the magazine consists of a coiled strip of screws 414, Fig. 29, the screws being retained in a corrugated paper strip by a self-adhesive strip 412. An appropriate length of strip is torn off, the screws are loaded, and the paper then pulled away. In a final modification, to enable a partially-empty magazine to be filled, the tool with a modified magazine 72b, Figs. 32 and 34, is pushed against a shoot 186b and releases an escapement pawl 418. Screws slide into the magazine until stopped by a pawl 460. The magazine is then withdrawn, and a hand-catch 452 is depressed to release both the pawl 460 and also a pawl 448. The pawls are carried on a modified slide 126b which is pulled back until the pawl 448 engages the top-screw. Feed then continues as in the other embodiments. Specifications 820,002, [Group XVII], and 820,003, [Group XXX], are referred to.