Patent GB-788055-A (GB)
Title: Improvements in or relating to powder actuated tools
IPC: B25C1/18
Filed: 1954-02-19
Abstract: 788,055. Explosively actuated fastener driving tools. RAMSET FASTENERS, Inc. Feb. 19, 1954 [May 14, 1953], No. 4933/54. Class 119 In an explosively actuated fastener driving tool, the barrel 22, Fig. 1 and breech block 37 detachably secured thereto are urged to a forward safety position by springs 26, 38 so that normally the breech block 37 is spaced from the firing pin 34 which is urged towards the breech block by a spring 35, rearward movement of the barrel and breech block to bring the latter adjacent the firing pin also effecting the cocking of the pin by means of a rod 40 on the breech block which engages a retractible pawl 42 in the firing pin to move the latter rearwardly against the action of its spring 35. Release of the pawl 42 from the rod 40 for firing is effected by pulling a trigger 46 so that its sear 46a moves the pawl 42 inwardly dear of the rod 40, the trigger being inoperative except in the rearward position of the breech block and firing pin. The breech block 37 is guided for axial movement only by means of a screw 39 travelling in a slot 30b in the firing mechanism housing 30, which housing together with the firing mechanism therein can be inserted as a unit in an opening in the front of a second unit comprising the integrally formed receiver housing 20a, hand grip 20 and' trigger guard 20b, the two units being secured by a screw 31. A screw 53 secures an outer tube collar 51 through which the barrel 22 moves, within an outer tube 54 and also secures a hinge bracket 52 to the outer tube 54, the screw 53 also ensuring axial movement only of the barrel by engaging in a slot 22b in the barrel. The breech block 37 is secured to the barrel by means of interrupted screw threads 22t, 37t, so that the' breech block threads 37t can pass through the gaps between the barrel threads 22t and be locked together by a small turning movement of the barrel relative to the breech block. A hinge ring 58 Figs. 1, 5 is positioned between spaced shoulders on the front of the receiver housing 20a and on the firing mechanism housing 30 and a pin 59 therein travels in an arcuate slot 30d in the housing 30 to permit the relative turning action for locking and unlocking the tool. Ears 58<SP>1</SP> on the ring 58 coact with rearwardly extending ears on the hinge bracket 52, a hinge screw 61 being screwed into the bracket ears while freely'travelling in elongated slots in the ears 58<SP>1</SP> so as to permit the relative axial locking and unlocking movement between the barrel and breech block. When the barrel has been unlocked and moved out of the breech block 37, the tool may be broken for loading as shown in Fig. 10. The barrel housing comprising the tube 54 and tube collar 51 is locked to the housing 30 when firing by means of diametrically spaced pins 63 Figs. 1, 8 engaging in holes in the housing 30 so that each pin 63 can telescope over a flat 51a on the tube collar 51 as the breech block 37 telescopes over the barrel 22; on relative turning of the barrel and breech block to lock the threads 22t, 37t together. the pins 63 are rotated into a groove 51b on the tube collar. 51 to, lock the barrel housing 51, 54 and housing 30 together. The breech block 37 is also locked to the barrel by means of an L-shaped pin 66 Fig. 7 having its short leg travelling above a flat 22c on the barrel, the pin 66 sliding in a through radial slot 51c in the tube collar 51 and a peripheral slot 51b. When the barrel is pushed in for firing, the shoulder at the left-hand of the flat 22c pushes against the short leg of the pin 66 so that the horizontal leg travels axially to the right past the pin 63, so that any attempt to rotate the housing 30 relative to the collar 51 for unscrewing the barrel would be prevented because the pin 63 cannot rotate-but of the groove 51b in to the flat 51a since the pin 66 blocks its travel. At the same time if the assemblies are not fully screwed together, full inward movement of the bars rel is blocked for safety purposes when the pin 66 abuts against the pin 63. Instead of locking-.the barrel housing 51, 54 and housing 30 by means of the pins 63, they may be locked by a. bayonet type connection in which the tube collar 51 and the housing 30 are provided with arcuately spaced lugs which engage one behind the other, the pin 66 in this case engaging into a space between the axially aligned lugs to prevent unlocking of the bayonet connection. A flash shield 24, Fig. 1, 12 is pivotally mounted on a plate 68 by a nut and screw 72, 73, the plate being secured to a tube 70 slidable on the barrel 22 and urged forwardly by the spring 26. Since the pivoting shield moves eccentrically with respect to the barrel axis, indicia and reference marks on the shield 24 and plate 68 provide an adjustable gage for spacing fasteners. A clamping screw 74 threaded into the shield 24 engages one of a plurality of notches in the plate 68 for securing the shield in any given fastener spacing position. The screw 74 is integrally formed with an ejection rod 65 for ejecting spent cartridges from the removable breech plug 56 or the hinge screw 61 Fig. 5  may be formed with a part 61a for the same purpose. A barrel cap 75 Fig. 1 forms a stop for the tube 70 and the right end of  the spring 26 is effective on the collar 51 of the tube 54 within which the tube 70 moves for axial movement only. The tube 70 has a polygonal outer surface thus providing equispaced passages between the tubes 70 and 54 for the passage of the gas. Since for safety reasons the shield 24 and its spring 26 should-be used;: barrel latching means 80-82 Figs. 1, 7 are provided between the right hand end of the spring 26 and the tube collar 51 and the arrangement is such that the latching means prevents full inward movement of the barrel 22 for firing unless the spring 26 is bearing against the part 82 of the latching means. An extension rod 95, Fig. 1 is used as a safety locking means to prevent inward movement of the barrel to the ready-to-fire position. The rod 95 is of tubular form with a threaded upper surface and is urged outwardly towards the shield 24 by a spring 94. A bracket 77 Figs. 1. 11 welded to the barrel housing tube 54 carries a spring-urged push button 97 through which the rod 95 passes, the elongated button aperture being threaded in its upper portion only, so that in the position shown in Fig. 11 the threaded portions of the rod 95 and button aperture engage to prevent movement of the rod through the aperture. If the button 97 is always depressed to disengage the threads when the tool is being operated, the rod 95 will always bear against the shield 24 and the shield and barrel can be pressed back to the ready-tofire position. However release of the button 97 will prevent movement to this position and makes necessary two hand operation of the tool except when the rod 95 is maintained in the fully retracted position shown in Fig. 1. When the tool is used with a barrel extension 84 Fig. 15 (not shown) the rod 95 is used to ensure that both the barrel muzzle and shield 24 are firmly. against the workpiece 25<SP>1</SP> on firing and that the barrel bore is not tilted substantially from the normal to the workpiece. The back of the firing pin 34 has an extension rod 34a which, when it emerges from an aperture in the receiver housing 20a serves as a combination tilt and ready-to-fire position indicator since it is not visible in the safety position of Fig. 1 or when the tool is tilted excessively as in Fig. 14 (not shown). In a modification Figs. 18, 19 (not shown), the rod 95<SP>1</SP> and push button 97<SP>1</SP> are formed with buttresstype threads so that the rod is always extended in its safety position against the shield 24 without requiring operation of the push button 971 but cannot be retracted unless the button is pushed in A storage recess 20d Fig. 1 is provided in the handle 20 for receiving the barrel extension 84 and a disc adaptor 86 for holding a flat disc on the muzzle which is pierced by the fastener before it enters the workpiece to limit penetration. Specifications 788,056 and 788,057 are referred to.