GB910754A - A method of breaking or disintegrating materials and a tool therefor - Google Patents

Abstract

910,754. Cartridge-operated tools. GROTSCH, G. June 5, 1959 [June 7, 1958; March 20, 1959], No. 19261/59. Class 119. A cartridge-operated tool for firing a bit or pin into solid materials such as concrete, brickwork and wood and which may be used for breaking or splitting such materials, comprises a barrel 1, Fig. 1, in which the enlarged integral or separate head 3 of a bit 2 is slidably guided, the head 3 being provided with a chamber 5 for a cartridge 5a and a hammer and slide assembly 16, 18 adapted to be thrust forward for effecting ignition of the cartridge and thereafter partly or wholly to absorb the recoil thrust of the powder gases. As shown in Fig. 1, the bit 2 and its head 3 are integral and free flight of the bit is prevented by a buffer 7 slidably disposed in the muzzle of the barrel and provided with a buffer spring 13 which absorbs the shock of impact when the head 3 strikes a shoulder 8 on the buffer. A rubber buffering element may be used instead of the spring 13. The buffer 7 is formed with an annular cutting edge 15 or serrated teeth. Alternatively, as shown in Fig. 3, the pinlike bit 46 and the head 3 are separate elements which are in loose contact via an extension 3a of the head, the buffer 7 retaining the head 3 but allowing free flight of the pin 46. Whereas in Fig. 1, the base 5b of the cartridge is openly exposed to the hammer 16 and its striker pin 24, the base 5b of the cartridge in Fig. 3 faces the direction of drive and the cartridge is located inside a holder 56 which is a slidable fit in a recess in the head 3. The hammer 16, Fig. 1, slides in the barrel 1 and is secured to the slide 18 by screw threads 17. The slide 18 is displaceable in a casing 25 provided with a butt 26 and a recoil spring 27 urges the slide against a locking ring 28 on the casing 25. For firing the casing 25 is held by the butt 26 and thrust forward against the pressure of the restoring spring 22. This movement entrains both slide 18 and hammer 16 and engages the striker 24 and cartridge. The inertial mass of the recoiling hammer and slide is several times greater than that of the bit so that the recoil thrust is absorbed by the spring 27. The tool shown in Fig. 3 is provided with a modified hammer and slide assembly and has a shatter guard comprising a shield 57 rotatably mounted on the barrel 1 and provided with a window 58, a cover-plate 59 being secured to the barrel and having a corresponding window 60. A torsion spring 61 urges rotation of the shield to bring the two windows out of alignment before firing. Alternatively, the shield may be a fixed member and the cover-plate arranged to rotate.