Patent GB-875802-A (GB)
Title: Improvements in or relating to fastener inserting tools adapted to be held in the hand of an operator
IPC: B25C1/04
Filed: 1957-11-15
Abstract: 875,802. Fastener inserting tools. BRITISH UNITED SHOE MACHINERY CO. Ltd. Nov. 15, 1957 [Nov. 15, 1956], No. 35603/57. Class 89(3) [Also in Group XXIII] A hand-held power operated fastener inserting tool comprises an actuating member movable relative to a body portion of the tool between a first condition and a second condition, and a locking device which is urged into a first condition in which it prevents movement of the actuating member from its first to its second condition and which is movable into a second condition in which it does not prevent such movement of the actuating member. In the exemplified embodiment, a nail driver 16 is carried by a piston 32 which is normally held retracted in its cylinder 24 by compressed air in a space 25 but which makes a driving stroke under the action of air from an accumulator 30 when the space 25 is vented to atmosphere through orifices 45. The orifices 45 are controlled by a valve disc 44 which is normally urged into sealing engagement with a face 54 on the end of the cylinder 24 by compressed air in a chamber 42. A spring 86 also tends to urge the valve disc 44 against the face 54. The chamber 42 communicates with a chamber 60 into which a compressed air supply inlet 74 opens. A spool shaped pilot valve 62 mounted in the chamber 60 over the driver 16 has a bore 68 large enough to permit the passage of air past the driver 16. The pilot valve 62 is urged away from the valve disc 44 by the spring 86 to close exhaust ports 70 against the flow of air from the bore 68 and to engage a castellated end 84 of a slidable sleeve 80 which carries a nail positioning nosepiece 14. To operate the tool the nosepiece 14, in which a nail is positioned, is pressed against the workpiece to cause the sleeve 80 to slide inwardly whereby the pilot valve 62 is moved against the spring 86 to allow the chamber 42 to vent through the bore 68 and ports 70. The venting of the chamber 42 allows the pressure in the space 25 to move the valve 44 against the spring 86 so that air in the space 25 escapes through the ports 45 causing the piston 22 to perform its driving stroke under the action of the air in the accumulator 30 which reaches the piston 22 through orifices 34 in the cylinder 24. The movement of the pilot valve 62 against the spring 86 also places the compressed air inlet 74 in communication with a passage 78 which then delivers compressed air to the nail supply mechanism to cause delivery of the next nail to the nosepiece 14 via the pipe 12. When the nosepiece 14 is released from the workpiece after driving the nail, the pilot valve 62 returns to its original position and the chambers 42, 25 and 30 are refilled with compressed air from the inlet 74 in readiness for the next nail driving operation. A safety device which prevents accidental operation of the tool, comprises a pin 127 slidably mounted in the valve block 40 and adapted to engage a bore 128 in the sleeve 80 when the sleeve 80 is in the inoperative position. The pin 127 is carried by a spring loaded lever 130 having a handle 136 which must be moved towards the casing 11 of the device to release the sleeve 80 for longitudinal movement.