Patent GB-1357748-A (GB)
Title: Fastener driving tool
IPC: B25C1/04
Filed: 1971-06-14
Abstract: 1357748 Fastener driving tools FASTENER CORP 14 June 1971 [15 July 1970] 27800/71 Heading B4C A pressure fluid, e.g. air, operated fastener, e.g. nail or staple, driving tool comprises a cylinder 26 movable away from a main valve member 40, to permit flow of fluid from reservoir 24 into the cylinder to drive a piston 28 and driving blade 30 on a working stroke, when chamber 54 is vented, and a control arrangement 50 (Fig. 1) or 130 (Fig. 8) including a safety valve 46 (Fig. 1) or 132 (Fig. 8), a trigger valve 48, and a fluid pressure operated piston 110 (Fig. 1) or 148 (Fig. 8), which control arrangement is such that venting of the chamber 54 is only permitted when first the safety valve is actuated by placing nose 34 of the tool against a workpiece and second the trigger valve is actuated. In the first embodiment (Figs. 1, 4, and 5) when the valves 46, 48 are not actuated the chamber 54 is open to the reservoir via port 92 in the stem 80 of the valve 46, and the valve piston 110 is maintained in the position of Fig. 4, the larger end of the piston 110 being in communication with the reservoir via passages 102, 104, 116 and fluid in the reservoir passing via passages 102, 104, 116, 94, between stem 80 and sleeve 82, and via passage 120 to act on the smaller end of the piston 110. Placing of the tool against a work surface effects movement of element 86 rigidly connected with the valve stem 80, which is thus moved to the Fig. 5 position. Fluid acting on the smaller end of the piston 110 now passes via passage 120 and between the stem 80 and the sleeve 82 to atmosphere, due to movement of sealing ring 124. The valve piston 110 thus is not moved and subsequent actuation of trigger operated valve 48 opens the chamber 54 to atmosphere via passages 56, 80A, 94, 116, 104 and fluted element 108. The tool then operates to drive a fastener. Release of trigger 106 or removal of the tool from the work surface will open the chamber 54 to the reservoir and the cylinder 26 will be returned to engage main valve member 40. Registry of passage 68 with passage 70, the latter being in communication with reservoir 24 via passage 74 when blade 30 is not in its initial position, will result in return of piston 28, fluid above the piston being exhausted via passage 67 and ports (not shown) in the tool housing. Actuation of trigger 106 before actuation of the safety valve 46 will result in the larger end of the piston being open to atmosphere via passages 116, 104 and fluted element 108. Thus the piston 110 will be moved by fluid acting on the smaller end to block the passage 94 from passage 104. Subsequent actuation of the safety valve 46 will not connect the chamber 54 with atmosphere and accordingly the tool will not operate. The alternative safety control arrangement of Fig. 8 includes a port 146 open to atmosphere. When first the safety valve 132 and then the trigger operated valve 48 are moved to their operative positions the tool will be operated, but if valve 48 is operated first passage 160 will be vented. Therefore supply of pressure fluid from the reservoir via passages 102, 156, around piston 148 between sealing rings 152, 154, via passage 158, between stem 134 and cylinder 136 and via passage 159 will force valve piston 148 to a position to block communication between passages 160 and 162 and open communication between passage 156 and passage 162. Subsequent actuation of the safety valve 132 will interrupt supply of fluid via passages 156, 158 and 56 to the chamber 54 but will effect supply to the chamber 54 via passages 156, 162, and 56. The tool will therefore remain inoperative. The Specification also discloses an embodiment (Fig. 12) not within the scope of the invention claimed. This embodiment is a tool similar to that of Fig. 1, but having a modified control arrangement 170. Operation of the tool to drive a fastener will occur when the safety valve 172 and the trigger valve 48 are moved to their operative positions, the tool operation not being dependent on the sequence of operation of the valves. However the control arrangement is such that release and reactuation of the trigger valve is necessary to effect firing of a second fastener.