Patent GB-1498667-A (GB)
Title: Machine having a rotary cutter
IPC: B26D7/12
Filed: 1975-04-17
Abstract: 1498667 Sharpening in situ AMF Inc 7 April 1976 [17 April 1975] 15840/75 Heading B3D A machine such as a tobacco cutting machine, comprises a cutter rotating about an axis 49 and having one or more knives with cutting edges lying in cylindrical surface 47, means for sharpening the cutter comprising a cup grinding wheel 50 mounted for rotation about an axis 51 slightly tilted out of a plane perpendicular to the axis 49, and a carriage 14 on which the grinding wheel is mounted and which is arranged to reciprocate along the full length of the cutting edges parallel to the axis of the cutter. The carriage 14 is slidable along a pair of guides 11, 13 mounted between a two part mounting structure 10 carried by a base structure 23. A chain 17 has its opposite ends connected to the carriage and runs over sprockets 19, 20 mounted on the structure 10 and through the lower guide 13. Sprocket 19 is mounted to rotate freely whereas sprocket 20 is drivable through an overload coupling by a reversible motor to effect movement of the carriage along the guides which are parallel to the axis 49 of the cutter. Abutments 41 on the carriage co-operate with members 38, 40 mounted on the structure 10 to actuate micro-switches 35, 37 to effect reversing of the motor and the direction of movement of the carriage. Pipes 25 are connected to a pneumatic system for withdrawing dust produced during grinding, and a bellows 32 and covers 34 protect the guides and chain 17. The cup grinding wheel 50 is mounted in a unit 16 on the carriage with the rotational axis 51 of the wheel at an angle of between 60 degrees and 88 degrees, for example 85 degrees, from the axis 49 of the cutter. The grinding unit 16 is pivotable about the guide 11 to an inoperative position 57 upon rotation of a handwheel 61 rotating a worm 71 engaging a quadrant 73 fixed to the carriage when bolts 53, which normally hold the guides unit 16 fast with a framework 56 secured to the carriage are released and a gate section 54 is moved about a pivot 55. The grinding wheel 50 is held by a clamp ring 76<SP>1</SP> on a support 76, Fig. 5, secured to a spindle 79 of an electric motor 82. The upper end of the spindle is rotatably mounted in a bush 88 keyed for axial movement in a housing 89. A trip lever 94 mounted on the grinder unit is actuated by one or other of strikers 95, 123, to provide a small or large axial feed of the grinding wheel, mounted on a casting 97 on the structure 10, the trip lever acting through a pawl and ratchet mechanism to rotate a worm 105 engaging a wheel 108 secured to a nut 110 meshing with a screw 111 which is thereby axially moved and is pinned to the bush 88 to cause a corresponding axial feed of the spindle 79 carrying the grinding wheel. Manual feed of the grinding wheel may be effected by a handwheel 104 connected to the ratchet wheel. A scale 113 indicates the amount of wear of the wheel and, when the wear reaches a predetermined amount, an abutment 117 carried by the scale actuates a micro-switch 115 to stop operation of the motor 82. A diamond dresser 130, Figs. 12 and 13, for the grinding wheel is mounted on a shaft 131 which is rotatably adjustable about an axis Y-Y be preset amounts to optimize the life of the diamond. The dresser is movable from an operative position along guide rods 137 to a position 138 in which the diamond face can be positioned against a gauge 140 by adjustment of a capstan nut 132 after slackening of a lock screw 143. In operation, the grinding wheel moves from right to left (Fig. 1) to grind the cutting drum knives. The leading edge of the wheel passes over the diamond dresser 130, the trip lever 94 is actuated to effect a downfeed of the grinding wheel, and the stop 41 actuates a micro-switch 37 to reverse the motor driving the sprocket 20 and energize a timer which after a preset time, energizes the motor to move the grinding wheel in the opposite direction across the dresser to effect dressing of the wheel and then to grind the cutters.