Patent GB-749843-A (GB)
Title: An improved grinder for the knives of tobacco cutting machines
IPC: B24B3/36
Filed: 1953-06-25
Abstract: 749,843. Sharpening machine cutters in situ. MOLINS, D. W., SMITHG., MASON, J. A. RUAU, F. F., and MOLINS MACHINE CO., Ltd. June 21, 1954 [June 25, 1953], No. 17660/53. Class 60. In a tobacco cutting machine of the kind in which knives 1 having straight cutting edges and projecting through a rotating cutter disc of head 2 move in a plane and sweep across a mouth 3 through which a cheese of compressed tobacco leaves is fed and cut thin slices from the end of the cheese, the cutting plane of the knives is tangential to the curved surface of a grinding wheel which surface is so located with respect to the path of the knives and their orientation with respect to the axis of rotation of the cutter..head that successive points along a knife edge making grinding contact with the wheel along a straight line. The grinding wheel 4, which protrudes slightly through an aperture 6 in a plate 5 flush with the front of the machine frame, is rotatably supported in a frame 7 pivoted, on a tubular shaft 8 to the machine frame 9. The wheel 4 is held between, a tapered upper stub staft 14 driven by an electric -motor 15, and a tapered lower stub shaft 16 journalled in a slidable bush 19 having a rack 20 engaged by a pinion 21 operable by a handle 24; a locking quadrant 25 is provided. A key 18 ensures rotation of the wheel. The wheel 4 is trimmed by a diamond 26 mounted in a holder 27 part of which consists of a screwed rod 28 threaded into a carriage 32 which is traversed to and fro parallel to the wheel by a long screw 33 journalled in the frame 7 and driven through an Oldham coupling 36 by an electric motor supported on a bracket 35. The carriage 32 carries rollers 56 which run on guides 57, 58 to prevent it from rotating; alternatively the nut may be guided by a fixed rod parallel to the screw.  When trimming of the wheel is required, the motor driving the screw 33 is started either by manual switching or by a clock-controlled switch. The carriage 32 then moves upwards, the diamond traversing the length of the wheel,until an abutment 37 fixed to the carriage strikes a push rod 38 to operate a micro switch 39 so reversing the motor for a downward traverse of the diamond. As the diamond reaches the top of its stroke, a bevelled face 37A of the abutment 37 moves a pin 40 to cause advance of the wheel. The pin 40 is fixed to a ring 43 on which is pivoted a pawl 42 urged by a spring 44 into engagement with a ratchet wheel 41 fixed to a nut 13. The nut is rotatably mounted in a bracket 7A pivoted at 7B in the frame 7; a screw 10 fixed to a sleeve 11 pivoted on a fixed shaft 12 is threaded into the nut. As the diamond goes down again, the pin 40 is released and the ring 43 is returned by a spring 45. At the back of the ratchet hub 41 is a gear wheel 46 meshing with a gear wheel 47; the latter may be rotated by a roller 48 so as to screw the nut 13 back fully on the screw 10 when a new grinding wheel is fitted; an indicator may be fitted to the collar to show the amount of useful wheel left. As the diamond approaches the end of the downward traverse and is clear of the wheel 4, a pawl 31 is operated to cause in-feed of the diamond. The pawl is pivoted on a rocking quadrant 49 pivoted on the diamond feed screw axis; a toe 50 on the quadrant strikes a bell crank lever 51 pivoted at 52. One arm 53 of the lever abuts a stop 54 while the other arm 55 is shaped as a sharp tooth adapted to engage the toe 50 and rotate the pawl quadrant; a spring holds the arm 53 against the stop 54. A spring detent device consisting of a double-armed lever pivoted at 63 engages by an arm 64 a serrated wheel 65 fixed to the ratchet wheel 30; the arm 66 is locked by a spring, so preventing accidental movement of the diamond holder 27. Dust and metal particles are removed by a suction duct 59 to which is attached a hood 60; auxiliary hood pieces 61, 62 are attached to the frame 7. The screws 28, 33 are protected from dust by bellows 29, 34. Specification 365,997 and 588,129 [Group I], are referred to.