Patent GB-956210-A (GB)
Title: Improvements relating to cutter sharpening machines
IPC: B24B3/02
Filed: 1962-09-26
Abstract: 956,210. Grinding cutters. GLEASON WORKS. Sept. 26, 1962 [Nov. 8, 1961], No. 36612/62. Heading B3D. A cutter-grinding machine having a frame 10 comprises a reciprocatable carriage 13 carrying a core-faced grinding wheel W which, during reciprocation, traverses the sharpening plane P, a bracket 34 supporting a work-head 27 for angular adjustment about an axis 33, substantially parallel to the direction of reciprocation of the carriage 13 (which is in the direction of the axis 14), and an index housing 25 which journals a cutter spindle 23 rotatable about an axis 24, perpendicular to and intersecting the axis 33, and is adjustable along the axis 24; the bracket 34 is pivoted to the frame 10 about an axis 39 which is perpendicular both to the sharpening plane P and the axis 33, and is spaced from the spindle axis 24 in the direction of reciprocation of the carriage 13 a distance such that, by movement of the bracket 34 about this pivot, a cutter C may be advanced and retracted in the plane P in a direction substantially perpendicular to the direction of wheel-stroking motion (i.e. in the direction of the axis 14) into and out of the path of the grinding wheel. The wheel spindle is journalled in the carriage 13 and is belt-driven by a motor 145, the carriage being reciprocatable both mechanically and hydraulically, by the mechanism 18 shown in Fig. 3, along the axis 14 and oscillated about that axis by a cam 67, Fig. 4, and a feed arm 58 supported by trunnions 15, 16, carried in a bracket 12; the bracket 12 may be positioned relative to the frame by means 22, Fig. 1, to bring the grinding wheel to a location W<SP>1</SP> when a cutter of opposite hand is to be sharpened. In operation, a pulley 45, driven by a motor 40, constantly rotates a pair of eccentric rollers 51, 52, which engage plane transverse surfaces 53, 55 on, respectively, an arm 50 secured to a piston-rod 54 and on a flange 56 of a hollow piston 57. A sleeve 61 slidable in the piston forms a part of the rod 54. Pressure admitted to a chamber 62 through a passage 63 in the sleeve 61 causes the piston 57 to move to the left until the flange 56 abuts a ring 64 secure to the bracket 12. The sleeve, rod and trunnion 16 then move to the right until the arm 58 abuts a sleeve 59 (as shown in Fig. 3), the rollers 51, 52 then being clear of the surfaces 53, 55 so that they idle with the shaft 48 and the wheel carriage 13 being in the position shown in Fig. 1, in which the wheel may be dressed or the cutter removed, or changed. On pressure being released from the chamber 62 and applied to the chamber 65 through a passage 66 the piston 57 moves to the right, Fig. 3, until the surface 55 abuts the roller 52 and the rod 54 and trunnion 16 move to the left, until the surface 53 contacts the roller 51; during the maintenance of this pressure, the carriage 13 is reciprocated by the eccentrics. Simultaneously, the cam 67 operates, in timed relation with the valve means controlling the pressure applied to the chambers 62, 65, to oscillate the carriage 13 about the axis 14 by the mechanism 19, Fig. 4, to move the grinding wheel into and out of the sharpening plane P. A piston 81 is hydraulically operated to hold a lever 69, interposed between the cam 67 and the feed arm 58, to prevent oscillation of the carriage during dressing of the grinding wheel. A ratchet mechanism 146, Fig. 9, hydraulically operated, provides an increment of wheel movement in the direction of the generator 138 of the conical wheel face 137 prior to each dressing, the increment corresponding to the amount of wheel surface to be removed during dressing. The indexing mechanism for the cutter may be of the kind disclosed in Specification 938,904. The cylindrical lower part 26 of the housing 25 is supported in a workhead 27 for angular and axial adjustment relative to the cutter spindle axis 24, by the means shown at 29 and 28 respectively in Figs. 1 and 2. The bracket 34 supports the workhead on trunnions 30, 35, the latter having a rack 37 and sector 36 for tilting the head about an axis 33 to vary the hook angle of the cutter blades. The bracket 34 is pivoted to the frame about an axis 39 along which it may be adjusted and hydraulically reciprocated by a piston 101 and cylinder 102, Fig. 5; the swing radius of the bracket about the axis 39 is such that reciprocatory movements of the cutter effected by the mechanism 42, Figs. 1, 2 and 6, is substantially in the sharpening plane and perpendicular to the grinding wheel stroking motions produced by its oscillation about the axis 14. Adjustment of the bracket 34 along its support 41 in the direction of the axis 39 by the means 86, 98, shown in Fig. 5, varies the off-set of the cutter axis 24 from the sharpening plane and thus determines the rake of the cutter blades. The mechanism 42 for raising and lowering the workhead 27 comprises a cylinder 108, Fig. 6, having upper and lower heads 109 and 111, main and auxiliary pistons 113 and 116, the latter being of ring form slidable on the pistonrod 115 which is taken through the cylinder head 111 to contact, in its lowest position a variable stop mechanism 152, 158, Fig. 7 (not shown), which enables the cutter to be held at one level for preliminary sharpening and at a different level for finishing. Application of pressure through a passage 126 raises the auxiliary piston 116 and the main piston 113 until a passage 127 admits pressure directly to the underside of the main piston which then completes its stroke to bring the cutter into the sharpening position; during indexing it is lowered to contact the raised auxiliary piston, the cutter being clear of the wheel path in this position. The dressing mechanism, Fig. 9, comprises a driven abrasive disc 128 rotatable about an axis 129 for dressing the face 131 of the wheel and a fixed element 132 for dressing the peripheral edge 133 of the wheel. Both elements are supported by an arm 134 pivoted to a housing 135, Fig. 1, movable about an axis 136 parallel to the axis 39; the housing is stationary on the frame 10, having means for swinging the arm about the axis 136 to cause the disc 128 to traverse the wheel face 131 and, when in its lowest position, to move the arm along the axis to the left, Fig. 9, to bring the fixed element into contact with the wheel periphery. When not in use, it is raised to its uppermost position and held clear of the cutter in its sharpening position.