Patent GB-1013750-A (GB)
Title: Device for grinding compound-convex surfaces
IPC: B24B3/20
Filed: 1964-09-29
Abstract: 1,013,750. Grinding; reamers; drills; taps. LAVALLEE & IDE Inc. Sept. 29, 1964 [Nov. 5, 1963], No. 39579/64. Headings B3C, B3D and B3N. A device for sharpening cutting tools, such as reamers, taps, drills and milling cutters, comprises a rotatable grinding wheel 14, Fig. 1, having an internal concavely curved grinding surface g generated by a curved line swung about the axis of rotation of the grinding wheel, and a tool holder 42 having means for positioning the end face of a cutting tool in engagement with the internal grinding surface to form a curved cutting edge thereon bounded by a compound-convex end face formed by engagement with the wheel, the cutting edge also being bounded by a longitudinal surface of the tool and the tool holder being adapted to position the tool with its longitudinal surface at an oblique angle to a tangent of the grinding surface at the cutting edge. The grinding wheel may be of cylindrical or conical cup shape and is mounted on the spindle 12 of a machine having a bed 10 movable vertically and longitudinally and transversely of the axis of the grinding wheel by means of lead screws 16, 18, 20. A plate 22 is mounted on the bed and has a pedestal 26 which is movable along a guideway 24 by a lead screw 28; the bed 10 may be magnetized to hold the plate 22 thereon. The pedestal 26 has upper and lower parts 62, 58 which are prevented from rotating relative to each other by pins 64 and have oppositely handed screw-threads engaging a sleeve 60, rotation of which vertically adjusts the upper part; the sleeve can be clamped in adjusted position by a screw 66. The upper part 62 rotatably carries a block 46 which is clampable in adjusted position by a screw 52 and supports a pivot 44 for the work-holder which is adjustably secured thereto. The work-holder receives a replaceable bush 70 which slidably receives a reamer R whose edges are to be ground. A pin 74 extends from the bush for engagement with a flute of the reamer for rotatably positioning the reamer and a collar 76 is releasably clamped to the reamer for engaging the holder to determine the forward axial position of the reamer. When the reamer is retracted to disengage the pin from the flute, the reamer can be rotated to present a further flute to the pin and another cutting edge to the grinding wheel. The holder is adjustable to a position in which the longitudinal axis of the reamer is inclined to the axis of the grinding wheel so that the face f, Fig. 5, on the end of the reamer has clearance relative to the cutting edge c, the face having a compound curvature. The concavely curved surface of the grinding wheel is formed by a diamond dresser 78 mounted on a bar 80 rotatable about an axis transverse to the axis of the grinding wheel by a knob 88, the bar being rotatably mounted in a support 82. In another embodiment, the work-holder 42<SP>1</SP>, Fig. 9, has a carrier 96 which, at its leading end, has an extension 100 carrying a centre 98 for supporting one end of the reamer R, and at its other end adjustably carries a screw 108 having a centre 106 for the rear end of the reamer. A collar 116 is mounted on the carrier for engaging the mount to control the forward axial position of the reamer, and a pin 110 is adjustably mounted on the holder for engagement with a flute of the reamer to rotatably position the reamer.