Patent GB-1503209-A (GB)
Title: Sharpener for cut-off having a helical knife
IPC: A24C5/30
Filed: 1975-06-14
Abstract: 1503209 Sharpening cutters in situ MOLINS Ltd 10 June 1976 [14 June 1975] 25472/75 Heading B3D A cut-off mechanism for a cigarette or other similar continuous rod making machine comprises a rotating helical knife and a device for sharpening the knife, the device having two rotary sharpening members 44, 78 arranged to act on opposite sides of the knife, both members being carried by a rotary member 38, 70 which rotates about an axis substantially parallel to the axes of rotation of the members, each member being adjustable in regard to its distance from the axis of the rotary member, and at least one of the members being driven by engagement of a rim 80 on the member with an intermediate wheel 84 which also engages a stationary ring 48 coaxial with the rotary member. The device is arranged so that the knife is sharpened after a plurality of cuts, e.g. 5. A shaft 10 is driven by the main drive of the machine and is secured to a disc 14 adjustably connected by a pinch bolt 18 to a second disc 16 on a hollow shaft 22. Gears 24, 26, 28 connect the shaft 22 to a gear ring 28 on a housing 30 journalled in bearings 32 in a frame 34. The housing is splined 36 to a hollow shaft 38 having a radial projection 40 along which a part 43 carrying the frusto-conical sharpening stone 44 is adjustable by a screw 42. During rotation of the shaft 38, the stone 44 is moved with an orbital movement and is rotated about its own axis by frictional engagement of a drive rim 46 with a ring 48 mounted on the frame 34 by a clamp 37. The shaft 38 is axially adjustable to vary the height of the stone 44 and is carried by a bearing 52 in a ring 54 having a screw thread engaging a thread 56 on a part 34a of the frame. A spring loaded latch 60 releasably locks the ring 54 in position but can be retracted by a knob 58 for rotation of the ring and hence axial adjustment of the shaft 38 and stone 44. A flange 64 at the upper end of the hollow, shaft 38 is adjustably connected by a bolt 68 to a flange 66 splined at 72 to a shaft 70 disposed within shaft 38. The lower end of the shaft 70 has a radial projection 74 along which a part 77 carrying a frusto-conical deburring stone 78 is adjustable by a screw 76. A drive rim 80 on the deburring stone engages ahardened steel tyre 86 supported by a deformable ring 88 on the intermediate wheel 84 which is carried by a link 82 and, during rotation of the members 30, 38, 70, urged by centrifugal force into engagement with the ring 48 to effect rotation of the stone 78 about its axis. The upper end of shaft 70 is supported in a bearing 52a in a similar manner to the hollow shaft 38 to permit axial adjustment of the shaft 70 and stone 78. The phase of the stone 44 with respect to the machine driven shaft 10 is adjustable by varying the relative angular positions of the flanges 14, 16 and the phase between the stones 44 and 78 is adjustable by varying the relative angular positions of the flanges 64, 66. The sharpening stone has a taper angle of 30 degrees and the deburring stone a taper angle of 150 degrees. In an alternative embodiment, both stones are driven by intermediate wheels mounted on pivotal links so as to be urged by centrifugal force into engagement with the ring 48 to drive the stones.