Patent GB-825198-A (GB)
Title: A honing mandrel
IPC: B24B33/08
Filed: 1957-10-21
Abstract: 825,198. Honing. SUNNEN, J. Oct. 21, 1957 No. 32756/57. Class 60. A honing mandrel has a radially adjustable abrasive stone mounted therein and a pair of soft metal bearing shoes on the mandrel circumferentially spaced from the abrasive stone and from each other so as to support the abrasive stone when honing a bore, the bearing shoes being adjustably mounted on the mandrel for rotation about axes parallel to the mandrel axis. A mandrel 10 has a radial slot 12 extending throughout its length and slidably receiving the rib 14a of a stone holder 14 the stone-mounting portion 14b of which is received in a transverse recess 20 at the outer end of the mandrel. A plate 16 lies in the slot 12 alongside the rib 14a and has a pin 23 entering a hole in the rib and retained therein by a spring ring 25 ; pads 26 are interposed between the under surface of the stone-mounting portion 14b and the top surface of the plate 16. The under surface of the plate 16 has cam surfaces 28 co-operating with cam surfaces 30 on the upper surface of a wedge member 18 received in the slot 12 ; the member 18 is adjusted longitudinally of the mandrel, so as to effect radial adjustment of the stone holder 14, by means engaging its projecting end 32. Outwardly of the recess 20 the slot 12 is partially closed by a semi-circular plate 34 pressed into a transverse slot in the mandrel and forming an outward stop for the stone holder 14. Inwardly of the recess 20 is a block 36 secured in the slot 12 by a screw 38 to form a guide for wedge member 18. A leaf spring 40 located between the ends of the block 36 and the stone holder 14 urges the latter against the stop member 34 so that it is frictionally held in the mandrel. The stone mounting portion 14b has attached thereto, e.g. by cement, two stones 22 and is die cast from soft metal; it is discarded when the stones are worn. The plate 16 is of hard metal with ground surfaces and forms a permanent element of the mandrel assembly. The outer portion of the mandrel also has a pair of longitudinally extending grooves 44 of arcuate cross-section each accommodating a bearing shoe 46 having a pair of spaced bore-contacting surfaces 50. The shoes 46 are of soft metal, e.g. zinc alloy, and are provided at both ends with short extensions 56 each having an arcuate groove 58 engaged by a projection on a clamp 60 secured by a screw 68 to the mandrel. Before honing, the shoe clamp screws 68 are loosened slightly, the mandrel is inserted into a bore to be honed and the stones 22 engaged with the bore; the mandrel is rotated slowly and tapped lightly, and is then withdrawn from the bore and the screws 68 tightened. Honing then proceeds. The inner end of the mandrel has an eccentric shank 72 on which is an eccentrically bored sleeve 74 received in a chuck or collet on the driving spindle ; opposed notches 78 in the sleeve are selectively engaged by a pin 76 projecting from the shank 72. In one position of the sleeve the mandrel body is concentric with the driving spindle, and in the other position it is eccentric thereto ; more than two notches may be provided. A spring retaining ring 82 located in an internal groove in the sleeve engages shoulders formed by a reduced portion 84 on the shank ; a spring pressed ball 86 is provided. The sleeve has apertures 80 providing access for shank engaging set screws in the collet acting against the tapered portion of the collet; notches 88 in the outer end of the sleeve 74 receive driving lugs. U.S.A. Specification 2,638,721 is referred to.