GB712083A - Improvements in or relating to reamers and screw taps - Google Patents

Abstract

712,083. Reamers; taps. OFFICINE MECCANICHE MAGAR SOC. R.L. Oct. 23, 1952 [Nov. 6, 1951; Feb. 22, 1952; Sept. 3, 1952], No. 26583/52. Class 83 (3). [Also in Group XXIII] A cutting tool, such as a reamer or tap for machining internal cylindrical surfaces, has a blade 9 with right-angled cutting edges 3, 4 and contacts the work by these edges and by a point 5 which is diametrically opposite the mid point of the line joining the edges, one edge cutting while the other acts as a guide, according to the direction of rotation of the tool. The blade may be integral with the body 1 or attached to it by radial screws as shown in Fig. 2 or by side screws or by wedges, adjustment of the cutting diameter being made by shims or by radial screws engaging the bottom of the blade. For reaming blind holes, the blade may extend to the end of the body. Fig. 10 shows a reamer in which the blade 9 is adjustable by a wedge 27 axially adjustable by screwed engagement with a graduated knob 24 ; after adjustment, the knob can be locked, by a screw 25 or screwed ring, to a boss 22 having handles 23. The blade may be held against the inclined plane 28 of the wedge by ring springs 60 or by leaf springs attached to the body and bearing on the ends of the blade. Since the radial adjustment of the blade displaces the centre of rotation of the tool by half the amount of adjustment, compensation for this in reamers intended for machine use may be obtained as shown in Fig. 12, where the wedge, adjusted by a screw 33, has a second inclined surface 28<SP>1</SP> of half the slope of the other surface 28, the surface 28<SP>1</SP> adjusting a rectangular shank 32 in a slot 31 in a sleeve 30 ; springs 35 urge the shank against the inclined surface and a pin-and-slot connection 37, 39 prevents axial displacement of the shank and sleeve. In a modification, the shank 50, Fig. 17, corresponding to the shank 32, is attached to a reamer, similar to that of Fig. 10, by arms 50<SP>1</SP> having surfaces slidably engaging . flats 51" on the reamer sleeve and adjustable on the flats by screws 56 on a ring 50" attached to the arms. In a non-rotating reamer for machining rotating work, the reamer is held in a bracket 40, Fig. 14, and the wedge 27 is adjustable by a lever 41 linked to it by a rod 43, the amount of adjustment being limited by a screw 44. The blades may be tapered to facilitate entry into the work or formed to ream conical or other shapes of hole and may be helically arranged. More than one blade may be arranged along the same axis or the cutting edge of a single blade may be interrupted along its length. For increasing the diameter of the reamer, a curved backing plate of hard metal can be attached in the region of the point 5. As applied to a finishing or tapered tap, a blade 69 arranged axially or helically may be secured by side screws 14, Fig. 24, or may be adjustable by a wedge 27, Fig. 26.