Patent GB-804313-A (GB)
Title: Head for power operated fastener-driving tool
Inventor: ZAKRZEWSKI ANDREW S
IPC: B25B23/04
Filed: 1955-04-28
Abstract: 804,313. Screwing-up screws &c. TAYMOUTH INDUSTRIES, Ltd. April 26, 1956 [April 28, 1955], No. 12235/55. Class 83 (3). A head for a fastener driving tool, e.g. a screwdriver, comprises a body 1 with a chamber to receive screws &c. from a tube 6 connected to a supply of fasteners, e.g. a serving machine, an adapter 2 for attaching the head to the screwdriver, the driving-shank 17 of which enters the end of the chamber opposite that at which is disposed means 4, 5 to hold the screws in driving position, and means 14 interconnecting the body 1 and adapter 2 and enabling the adapter, and hence the driving tool and its shank 17, to be advanced, relatively to the body 1 and against the influence of a biasing means 18, between the inoperative position illustrated and an operative position wherein the shank engages a screw in position to be driven. The bar 14, provided with a stop-plate 15 to bear against the body of a valve 3 in the adapter to prevent escape of the body 1 upon expansion of the spring 18 surrounding the shank 17, is adjustably secured to the body 1 by a screw 32, and slides in the adapter as the shank is brought into the operative position. A T-shaped leaf spring 11, in the crotch at the junction between the chamber and tube 6, guides the screws into the chamber, from which they are forced, by the compressed air or by the driving shank 17, beneath a spring-pressed latch 7 pivoted on a screw 8 to engage behind the heads of the screws and so prevent their return to the chamber. Jaws 4, closed by springs 5, hold the screws until they are driven out of the gripping-zone by the rotating shank 17 which, in its advanced position, engages and tilts the spring 11 to cover the end of the tube 6 and prevent delivery to the chamber of a further screw until the shank has been withdrawn. The serving-machine is controlled automatically, through the valve 3, by operation of the screwdriver, and a pawl 26 on the adapter 2 co-operates with recesses 29, 30, and an intermediate, shallownotch 31 in the bar 14 to ensure that when the serving machine has delivered another screw to the tube 6, the shank 17 cannot be withdrawn to allow the spring 11 to return and the screw to fall into the chamber, until it has passed through its fully-advanced position and cleared the jaws 4 to receive the other screw. As illustrated, the valve is arranged to allow the escape of compressed air through a clearance between the seating 20 and a pin 24 which is supported on the stop-plate 15 and holds back a ball 22 pressed forward by a spring 23 and the compressed air, the latter being fed to a nipple 21 on the valve from a relay (not shown) controlling the serving machine. When the screwdriver is thrust forward to drive a screw, the body 1 and adapter 2 move towards each other, and the bar 14 and pin 24 slide in the adapter and valve respectively, the ball 22 engaging the seating 20 and interrupting the escape of the compressed air, and hence operating the relay controlling the supply of a further screw from the serving machine, when the pin 24 has moved out of the valve. The pawl 26 is pivoted against the rod 14 by a spring 28, and is rocked to the other side of its pivot 27 on encountering the first recess 29 in the sliding rod 14. As the notch 31 reaches the pawl, the ball seats against the seating 20 to operate the serving machine, which blows a further screw into the tube 6. The notch, being too shallow to permit rotation of the pawl as do the notches 29, 30, prevents the separation of the body 1 and adapter, which must be brought further together to eject the screw held by the jaws 4 before the pawl can enter the recess 30 and be rocked into a trailing attitude unaffected by passage of the notch 31 as the body and adapter separate. The bleed valve 3 or, alternatively, a normally closed valve, may be mounted on the serving machine and operated through a cable from an element mounted on the head. Specification 804,314 is referred to.