Patent GB-1057287-A (GB)
Title: Fastener applying device
IPC: B25C1/04
Filed: 1965-06-04
Abstract: 1,057,287. Stapling and nailing machines. SENCO PRODUCTS Inc. June 4, 1965 [June 5, 1964; April 6, 1965], No. 23946/65. Heading B4C. A pneumatically-actuated tool for driving nails or staples comprises a piston 44 reciprocable in a cylinder 38 and controlled by means of a firing valve 22 initially opened by a control valve 116, Fig. 4, a valve 164 adapted to allow a portion of the compressed air admitted to the cylinder to effect closing of the firing valve, and a further valve 154 adapted to be actuated by the piston at the end of its return stroke in order to control the reopening of the firing valve to initiate a new cycle. With the tool in the position shown in Fig. 1, compressed air is fed from a reservoir 14 through passages 104, 107 to act on the firing valve and maintain it closed, the air above the piston 44 being exhausted via a valve disc 32 and passages 66,68 leading to atmosphere. Upon depressing a trigger 124, the valve 116 is moved to a position wherein an 0-ring 120 prevents the compressed air from acting on the firing valve, the area above the firing valve being exhausted via passages 107, 112, Fig. 5 (not shown) and 114. The air then acting on the surface 22b of the firing valve opens the latter so that the piston is driven on its working stroke. Upon release of the trigger, the control valve is returned so that the air again closes the firing valve in order that the air above the piston may be exhausted via a valve disc 32 and passages 66, 68, and the piston returned by air compressed in a chamber 56 on the working stroke. If it is desired for the tool to re-cycle automatically without again releasing the trigger, the latter is depressed still further against a resistance developed by air pressure acting on a member 96, 98, Fig. 5 (not shown), so that the control valve moves to a position wherein the valve 164 is opened, the exhaust port 114 being closed by the control valve. After the piston has effected its first working stroke, air pressure in the cylinder opens the valve 154 thereby allowing the air to act on the firing valve, via passage 158, throttle valve 162, valve 164 and passage 170, so as to close the firing valve. Air above the piston is then exhausted via valve disc 32 and passage 66, 68 thereby allowing the valve 154 to close. When the piston nearly reaches the end of its return stroke, it abuts the tubular end 146 of the valve 154 so as to allow the air acting on the firing valve to flow to exhaust; the latter valve then opens and the cycle automatically repeats itself. The speed at which the tool re-cycles is controlled by the adjustable throttle valve 162. In a modification, Figs. 6 and 7 (not shown), the valve 164 adapted to be operated by the control valve 116, is replaced by a spool valve 211 which in one position permits the tool to make a single working stroke for every operation of the trigger and, when moved manually to a second position, allows the tool to re-cycle automatically as in the previous embodiment. The tool is prevented from being actuated until the nose of the machine is in contact with a workpiece, by means of a cam 84, Fig. 5 (not shown), which is moved out of a blocking position by means of a lever 126 when the nose is pressed against the workpiece.