Patent GB-772351-A (GB)
Title: Improvements relating to explosively actuated hand tools
IPC: B25C1/12
Filed: 1953-07-27
Abstract: 772,351. Explosively actuated hand tools. SCHULZ, W. July 27, 1953 [July 26, 1952; Sept. 1, 1952 ; Jan. 24, 1953 ; June 25, 1953], No. 20715/53. Class 119. An explosively actuated hand tool for firing nails, pins, &c. into walls, ceilings, or other hard structures, has a recoilable breech block which forms the rear of the cartridge chamber at the moment of firing, the reactive force of the explosion gases being substantially absorbed in causing the recoil of the breech block within the tool. In one form, the barrel 32, Fig. 1, is axially displaceable relatively to a tubular housing 31 in which is movable a breech block 39 carrying a firing pin 40. The breech block is urged forwards by a spring 42 and a releasing and locking device for the breech block is provided on a ring 44 held to the tube 31 by a screw 45 engaging in one of notches 46. A spring-urged catching lug 49 is slidable in a recess in the breech block 39 and a fixed catching lug 50 is provided on the ring 44 together with a movable release stud 51 actuated by a lever 53 and push button 52. In order to fire the tool, the lever 53 is depressed to move the stud 51 and permit the breech block to move forwards until the lug 47 abuts the lug 50: the button 52 is then pressed in and the stud 51 presses in the lug 47 to disengage it from the lug 50 whereupon the breech block moves forward and the shot is fired. The breech block then recoils, its lug 47 moving past the lug 50 and stud 51 and on moving forwards again under the action of the spring 42, the lug 47 strikes the stud 51 and the breech block is thus intercepted. The breech block may be in the form of a piston sliding in the tube 31 which in this case is not slotted as shown in Fig. 1 and is provided with a modified locking and release device shown in Fig. 4 (not shown). Fig. 5 shows a breech block 71 with a relatively movable spring-urged firing pin 70 carrying a mass 74 so that when the forward movement of the breech block is arrested by the cartridge chamber, the firing pin 70 moves forward under its own momentum to fire the shot. This form of breech block and firing pin may be used in a tool incorporating a cartridge magazine, the forward movement of the breech block feeding a cartridge from the magazine to the cartridge chamber. The propelling force of the cartridge may be regulated by using interchangeable breech blocks of different mass and the same effect achieved by adjustment of the spring 42 Fig. 1 by screwing the abutment 43 to a greater or smaller depth into the tube 31 or by varying the distance between breech block and cartridge chamber by adjusting the position of the ring 44 on the tube 31. The breech block may consist of a number of component parts connected together by springs. Fig. 6 shows a tool with a different form of breech block spring which is disengaged from the breech block during its recoil so that the recoil forces are not transmitted to the hand of the operator. The spring 77 is secured externally of the tube 31 and in preparing for firing, it is arched by means of a handle 83 and a knife edge 78 on the spring introduced into a recess 79 in the breech block 39. Fig. 6 shows a position of the breech block during its movement towards the cartridge after its release (the releasing device not shown). Immediately before impact of the breech block against the cartridge, the spring 77 is extended almost straight and swings laterally from the breech block in the direction of the arrow 80, thus playing no part in opposing the recoil of the breech block. If firing vertically downwards the breech block is braked by its own weight and/or by compressing the air in the tube 31 which escapes from an adjustable aperture 81 or between a gap between the breech block and tube 31. Alternatively the breech block may be braked by a number of masses 84, 85, 86 Fig. 7 (not shown) which are set in motion or by an elastic cushioning device. In a further embodiment a variable annular gap 103 Fig. 8 is provided between the barrel 95 and cartridge chamber 98 for adjustment of the firing power as described in Specification 772,352. The breech block 92 is formed with a narrow fore part 112 which enters a tubular extension 113 on the cartridge chamber and has an integral firing pin 94. Behind the breech block is a further recoilable part 115 spaced therefrom by a spring 116 and behind the part 115 there is a spring 93 abutting against the base of the casing tube 91. A fixed lug 117 limits the forward movement of the part 115. The breech block is held back by a movable catch lug 118 which on retraction permits forward movement of the breech block under the action of the spring 116. On recoil, the spring 116 is compressed and the breech block 92 strikes the part 115 which is set in motion compressing the spring 93 until the recoil is absorbed. The barrel 95 is axially movable relative to an outer tube 96 which is hinged at 105 to the tube 91 and a locking device 106 holds the tubes 91, 96 in co-axial position during firing. A ring 114 arrests the forward movement of the breech block to prevent firing in the event of the barrel and cartridge chamber not being pressed back relative to the outer tube 96. A hook 120 Fig. 10 holds the cartridge in the chamber 98 and is provided with a bevel so that it is cammed aside by the breech block and does not prevent ejection of the cartridge. Alternatively a pivoted arcuate part 121 Figs. 11, 12 (not shown) having a bevel is provided. The rear end of the tube 91 Fig. 8 may be telescopically extensible by providing a spring cap which is forced back on compression of the spring 93. The locking device for the tubes 91, 96 comprises a hook 106 Fig. 14 pivotally mounted on the tube 96 and spring urged to engage in a recess 125 in the tube 91, the arrangement being such that the barrel cannot be pressed in and the shot fired until the hook is engaged in the recess 125. Other hooks are provided which are spring-urged to disengage and which are engaged automatically when the barrel is pressed in. Alternatively the hooks may be arranged externally of the tubes 91, 96 and engaged by a ring which is connected to a handle adapted to yield resiliently and which is moved when the barrel is pressed in, or the hooks may be mounted on the tube 91, instead of tube 96, so that when disengaged from their locking recesses, they interrupt any forward movement of the breech block. The tool shown in Fig. 8 may be provided with a releasing device for the breech block as shown in Fig. 1 or in Fig. 4 (not shown) or with the releasing devices described with reference to Figs. 16-20 (not shown). Fig. 21 shows a further embodiment in which the breech block 162 is displaceable in a tubular sleeve 161, the firing pin 165 being slidably mounted in the breech block and both being shown in the positions they occupy before the barrel 163 is pressed in. The firing pin 165 is urged forwards by a spring 166 into a position in which a collar 168 on the pin bears against a ring 167. On pressing in of the barrel, the cartridge chamber 164 and breech block 162 are moved back with the barrel, the pin 165 and ring 167 also being moved back and the spring 166 becomes compressed. Lateral displacement of the ring 167 by means of a. lug 170 on a trigger 169, then releases the pin 165 and the shot is fired, the pin 171 on the ring 167 being brought opposite the lug 170 when the barrel is pressed in. The breech block recoils against the action of springs 166 and 172 and at the limit of its rearward movement it is intercepted by a friction locking device comprising a roller 173 and an inclined plane 174. The barrel sleeve 175 is hinged at 176 and after release of a catch 128 the tool can be opened for recharging and at during this hinging movement a bar 179 is pushed back by a cam disc 178 to push back the roller 173, thus releasing the breech block which moves forward. The firing pin 165 has a collar 181 which is guided in a fixed sleeve 182 on which slides a sleeve 165a secured to the pin 165 and one end of which forms an abutment for the spring 166. When the breech block 162 moves to the forward position, then pin 165 cannot entirely follow the movement but is arrested by abutment of the collar 181 against the bottom of the sleeve 182, so permitting the ring 167 to spring under the pin collar 168. The firing power is adjusted by longitudinally shifting the barrel 163 in relation to the cartridge chamber 164 in a similar manner to that described with reference to Fig. 8 and as described in Specification 772,352.