Patent GB-196716-A (GB)
Title: Improvements in machines for grinding the blades of lawn mowers
IPC: B24B3/42
Filed: 1922-02-06
Abstract: 196,716. Brown, C. F. Feb. 6, 1922. Cutting-edges, shaping- and treating. - A machine for grinding the blades of lawn-mowers comprises a grinding-wheel which is reciprocated past the blades. The rotary blade assembly and the stationary cutter-bar may be ground separately when removed from the mower, or the rotary blade may be ground while in position on. the mower, which is, after removal of the handle and roller, mounted on the machine. As applied to grinding the blades when removed from the mower, the machine comprises a bed 1 on which is mounted a work-support 2 adjustable by screws 3, 8. The support carries adjustable brackets 15 having sockets 16 to receive the blade-carriers. On the bed are tracks 17 connected by crossmembers 61, 62 and supporting a slidable carriage 18. Mounted on the carriage is a plate 22 on which is supported a motor 36 and a pedestal 37 carrying a grinding-wheel 41 driven by the mctor. The plate is adjustable towards and from the work by a rack 30, Fig. 4, on the carriage and a pinion 31 mounted on an arbor 27 rctatably carried by the plate. The plate may be locked in adjusted position by a nut 35 on the arbor. The motor shaft 44 drives, through worm-gearing 45, 46, 49, 50, a shaft 51 passing through a plate 55 and carrying a pinion 56 gearing with a spur-wheel 57 rotatably mounted on a spindle 58 carried by the plate 55. The plate is rocked about the shaft 51, to bring the gear 57 alternately into engagement with two racks 59, 60 secured to the bars 61, 62, whereby the motion of the carriage may be reversed. The plate is rocked by means of a bar 63 which has pins 65 extending into diagonal slots 66 in the bars 62, whereby, upon moving the bar 63 endways, it also moves laterally, the lateral movement being communicated to the spindle 58, the lower end of which extends into a channel in the bar 63; the bar is moved by a lever 67. The cutter blades are partially rotated, to keep them in contact with the grinding-wheel, by the engagement, with the blade being ground, of an adjustable guide 81 mounted in a bracket 83, Fig. 4:. The fixed cutter-bar of the mower is supported during grinding by members 87, Fig. 11, which fit into the sockets 16. When the rotary cutter is to be ground without removal from the mower, the mounting of the grinding-wheel is modified as shown in Fig. 8. The grinding-wheel 41 is mounted on an axis perpendicular to that of the rotary cutter, and is driven through bevel-gearing 73, 74 from a shaft 68a mounted in the pillar 37 and driven by the motor. The grinding- wheel is carried by a frame 71 pivoted on the shaft 68a and is supported and guided by the stationary cutter bar 80 of the mower which is engaged by a screw 71b carried by a lever 71a pivoted in the frame 71. The lever is guided at its inner end by a pin 71<c> carrying an adjusting- nut 71<e>. A second lever 72a is provided, having an extension 72<d> which engages under the bar 80 and is held thereto by the arm 73<b> of a lever 73<a>. By adjustment of the screw 71<b> and the nut 71<e> the cut to be taken from the blade is determined. A pin 41a on the frame 71 engages the blade 80a being ground and causes partial rotation thereof during the reciprocation of the grinding-wheel.