GB1386071A - Recessing or similar tools - Google Patents

Abstract

1386071 Boring bars; expanding cutters P A KEEN 28 March 1972 [29 Dec 1970] 61497/70 Heading B3C A recessing or similar tool for machining a bore 9 in a workpiece has a mounting shank 1 which is axially movable relative to a body 3, 4, 5 on engagement of the body with the workpiece or a locating member at the bore and as a result of this relative movement, piston and cylinder means such as a piston 15 as shown fixed to the shank and cylinder 14 formed in body part 4 is operated and fluid forced therefrom, for example along passage 17, operates a further piston and cylinder means 20, 19 in head 5, which is arranged to carry or actuate one or more cutters 6, and thereby effecting lateral or radial extension of the cutter(s). Extension of the cutter 6 secured in the piston 20 by its shank 16 engaged by screw 22 may be limited by spring-loaded nut 26 screwed on piston shank 27. Excess fluid may flow along passage 31 to reservoir 30 and act on spring-loaded piston 32. Retraction of the cutter is assisted by springs 23, 29. The body part 4 may bear on the workpiece by means of collar assembly 40 incorporating a rolling bearing so that no surface rubbing takes place. Other arrangements of apparatus include extensions for head 5 and replacements for collar 24 for use with bores of different sizes (Figs. 3, 4, not shown), two pistons with cutters (Figs. 7 and 8, not shown), a single piston with two cutters (Fig. 6, not shown) and a backfacing arrangement (Fig. 9, not shown). If it is required that the recess formed should be wider than the cutter width, e.g. recess 7a, Fig. 10, axial movement of the cutter in the bore, after full radial extension, is provided by incorporating an attachment comprising a rear actuating section 70 clamped to sleeve 2 on the shank 1 and a forward section 80 of telescopic sleeves, whose innermost 81 is secured to the rotatable part 44 of collar assembly 40. Head 5 is mounted on a spacer 54. After a recess the width of the cutter has been machined by the method above, continued axial movement of the shank 1 permitted by the available excess of movement of piston 15 in bore 14 and the provision of reservoir 30, causes sleeve 73 to engage sleeve 83 and rib 87 moves away from balls 84 which normally hold sleeves 81-83 axially locked. The tool body then moves relatively to sleeve 82 and against springs 88, 91 and cutter 6 moves down the bore.