Patent GB-1067448-A (GB)
Title: Improvements relating to apparatus for sharpening rotary cutters
Inventor: WARD HARRY
IPC: B24B3/38
Filed: 1963-06-13
Abstract: 1,067,448. Grinding. AMF INTERNATIONAL Ltd. June 10, 1964 [June 13, 1963], No. 23637/63. Heading.B3D. A machine comprises a rotary cutter 10, Figs. 1 and 2, which may be of the drum type used for cutting leaf tobacco, rotating about an axis and having one or more knives 8 with cutting edges lying in a cylindrical surface, a disc grinding wheel 26 mounted for rotation about an axis substantially perpendicular to a plane containing the axis of the cutter, the rim of the grinding wheel being hollowed to match the cylindrical surface, a carriage 24 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 and to dwell at one end of its reciprocating movement, and a dresser 56 for maintaining the contour of the hollowed rim of the grinding wheel, mounted on an arm 60 which is pivoted about an axis parallel, adjacent and adjustable with respect to the axis of the cutter at the end of the cutter at which the carriage dwells. The cutter is mounted on a shaft 12 supported by uprights 14 which are pivoted to a main frame 16 and adjustable to position the cutter relative to a mouthpiece 6 through which leaf tobacco is fed by conveyers 2, 4. A beam 18 extends between the uprights and has projections 20 supporting tubular rails 22 along which the carriage 24 is slidable. The carriage has a post 36 on which is pivoted an arm 34 which at its outer end supports a rotatable shaft 32 carrying the grinding wheel 26 and a pulley connected by a belt 30 to a motor 28. The position of the grinding wheel is gradually moved to compensate for wear by an adjusting mechanism 38 acting between a housing 40 on the carriage and lugs 42 on the arm. Reciprocation of the carriage is effected by a roller 48 which is carried by a chain 50 and engages a slot 47 in the carriage, the chain running over a sprocket 52 and two smaller sprockets 54 providing a vertical straight run to provide a dwell for the carriage at a position with the grinding wheel adjacent the dresser. The dresser consists of a diamond (58, Fig. 7) adjustably mounted on the end of the arm (60) which is pivoted on an eccentric sleeve 62, in turn, journalled on a fixed bush (64) coaxial with the shaft (12) of the cutter. In .order to accommodate the reduction in radius of the knives caused by grinding and to effect progressive grinding of the knives, the eccentric sleeve is adjusted so that the axis (Y) about which the arm (60) moves is below and slightly forward of the axis (X) of the shaft (12). Rocking of the arm is effected during the dwell period of the carriage by a second roller coaxial with the roller 48, Fig. 2, engaging a cam 74 on a link 72 mounted on pivoted levers 70, 68, the lever 68 being connected by a link 78, bell crank 72 and link 84 to the arm. When the diamond has been adjusted by a device (112, Fig. 7) to its correct radial position, the arm can be swung to a position in which a screw (116) can be adjusted to just contact the diamond, the screw then serving to permit assessment of the amount of wear of the diamond. The mechanism 38 for feeding the grinding wheel towards the cutter to compensate for wear consists of an abutment 86 which is on an arm (88, Fig. 4) and strikes a fixed abutment when the carriage reaches its dwell position. The arm is on a shaft (92) having two pawls (94) which co-operate with ratchet wheels (96, 98) differing by one tooth. Ratchet wheel (96) is in screw-threaded engagement with a shaft (100) connected to the lugs (42) on the arm (34) carrying the grinding wheel, and ratchet wheel (98) is connected by a key (102) to the shaft 100. When the abutment (86) is moved the pawls rotate the ratchet wheels one tooth, the shaft (100) moving an amount corresponding to the difference in angular pitch of the teeth. The abutment (86) can be swung to an inoperative position to permit the arm (88) to move to a position in which the pawls are out of engagement with the ratchet wheels to enable the shaft (100) to be rotated by a hand wheel (110) during the setting up of the machine. The knives 8, Fig. 1, of the cutter are fed forwardly at the end of each reciprocation of the carriage a small distance to take up wear and the amount removed by grinding by pneumatic cylinders 104.