GB407323A - Method and means for shaping the internal surfaces of barrels of firearms or other projectile propelling apparatus - Google Patents

Abstract

407,323. Boring and rifling gun barrels. GERLICH, H. E. G. T., Oakdene, Hurst Road, Bexley, Kent. Sept. 9, 1932, No. 25135. [Class 83 (iii).] In boring and rifling the barrel of a projectilepropelling device, the groove-bore of which is to have portions of constant and varying diameter, the lands bore is first cut and then the bore is rifled by means comprising two or more cutters arranged in groups, each group being in one plane and perpendicular to the axis of a cutter box carrying the cutters, and a pattern rod controlling the cutters disposed axially with respect to the cutter-box having a part shaped similarly to the required part of the barrel to be cut. In a machine for the boring operation, Fig. 1, the tubular cutter box 5 rotated by gearing 8 passes within the bore of a gun barrel 1 and is guided by a ball-bearing bush 6. Axial feed of the cutter-box is effected by a screw and nut 9, 10, while the relative axial motion of the pattern rod 11 and cutter-box necessary to feed the cutters radially is by the screw and nut gear 12, 13 actuated by a ratchet device. For rifling, Fig. 6, the cutter box is rotatably connected to a slide 28 which moves on ways 29, the limited rotation necessary to give the required pitch is effected by an adjustable slotted link 33 which controls rack and pinion mechanism 31, 32 ; thus as the cutterbox is fed axially it receives a limited rotative movement, a link with a curved slot may be substituted for that shown. The cutters 17, Fig. 8, have domed ends urged against the pattern rod 11 by springs 20 the cutting edges 18 are wider than the adjacent part of the cutter, Fig. 4, to provide clearance for chips and for rifling the plane of the cutter may be inclined to the axis of the cutter-box, Fig. 3. The pattern rod may be used for shaping the bore, which may be effected in a number of cuts including working from both ends of the barrel, and then substituted by another for the rifling which is of varying depth; the pattern rod, Fig. 4, is of rectangular section but may be circular when required, in which case it may be clamped to the cutter-box and used for boring a length of constant diameter ; more than one set of cutters may be used and also pilot pins of similar form to the cutters may be fitted to the cutter-box to guide the same after the first cut in a rifling operation. Pivoted cutters are described and modifications of the machine in which the work rotates in lieu of the cutter-box. Specification 374,091, [Group XXI], is referred to.