| 摘要 |
1,238,231. Fastener driving tools. HILTI A.G. 7 Jan., 1969 [3 April, 1968], No. 915/69. Heading B4C. A tool for driving fasteners into concrete or like material having a housing 11, a barrel 17, and a fastener driving piston 19 comprises a guide 12 connected by a bayonet-type connection 10 to the housing and a mass 14 surrounding the barrel and urged against a stop ring 13 by a spring 16. In operation the tool is pressed against a work surface and the barrel and mass are displaced. During a fastener driving operation the mass will minimize spalling of the work surface. The mass is preferably annular in crosssection and its outer diamter should be at least 40 millimetres, a diameter of 60-70 millimetres being preferred for fasteners having thick shanks. Its weight is preferably 400-600 grams although it may be of greater or lesser weight. The bore 15 is sufficient to allow radially play of the mass relative to the barrel. In a modification (Fig. 3, not shown) a tubular ring (20) of leather or plastics containing sand, or an incompressible plastic substance or similar pliable material is connected to the mass in a position in which it will contact the work surface. |
