Patent GB-712982-A (GB)
Title: Improvements in and relating to pencil sharpening machines
IPC: B43L23/02
Filed: 1950-09-13
Abstract: 712,982. Pencil-sharpeners. GUHL, A. Sept. 13, 1950 [Sept. 16, 1949], No. 22486/50. Class 146(3) A pencil-sharpening machine comprises a rotary sharpening tool and means for gripping and rotating the pencil; the gripping means also serving to positively advance the pencil towards the tool. The sharpening tool may be a milling cutter, a twobladed cutting tool 16 formed with straight, curved or angled blades, or an abrasive disc, and is rotated from a shaft 15. It engages the underside of the pencil 48 so that, during a cutting operation, the pencil is urged leftwardly, Fig. 2. The shaft 15 is driven through a slipping clutch connection from a high speed electric motor and, by a worm gearing 14, drives a pinion 12 engaging with a gear-wheel 10 having a flange 17 to which is pivoted on pins 18, Fig. 4, the gripping means shown comprising members 19 each carrying a pencilengaging toothed wheel 21 and urged centrally towards the pencil by springs 23. The pencil 48 is thus rotated through the reduction gearing relatively slowly by sharp forward edges of the teeth of the wheels 21, which by engaging in a spiral groove 7 in a boss on an end flange 3 screwed to a main housing 1, cause the pencil to be fed to the right, Fig. 1. The arcuately moving portion of the clamping members 19 has a pin 9 serving to anchor the springs 23 but which also engages in arcuate slots 60, Fig. 1, in a rimmed disc 8 freely rotatable on the grooved boss 7. The rim 24 of the disc 8 rotates between a gripping device 25 formed with protrusions 25a on a lever 26 centrally pivoted on a starting lever 29 concentrically mounted on a rim on the housing 1. Depression of the end 31 of the lever 29 will cause the lever 26 to turn under the influence of a spring 36 and the protrusions 25a grip the the rim 24 which thus turns and the slots 60 in the disc 8 cause the pins to ride outwardly and the toothed wheels 21 are spread to receive a pencil. At full depression of the lever 29 a stop 28 on the housing 1 engages the lever 26 so moving the protrusions so they do not grip the rim 24 and latching it in position by a pawl 33. At the same time this action closes a switch and the motor starts. When the lever 29 returns to normal, a stop 35 unlatches the pawl 33 from the lever 26 in readiness for a subsequent operation, and the members 19 and toothed wheels close round the pencil. If no pencil has been inserted the grippers return fully to their most central position and in so doing cause the motor to stop since a pawl, fitted in the flange 17 of the gear 10 has not been moved free of engagement with a motor disconnecting switch. The motor is also automatically disconnected when a pencil is sharpened since, as shown in Fig. 7, the point engages a lever 40 which through a connection 41 raises a spring plunger 37 sufficiently to allow a spring lever 45 to be released and operate a switch. The lever 40 has an adjustable pivot 42 and the lever 45 has an arcuate portion 47 which, gives an additional movement to the lever 40 so that it is just clear of the pencil point. Sharpening is completed by the inertia of the machine. The housing may incorporate a seal to prevent entry of shavings removed from pencils during sharpening and which comprises either a rubber disc or a series of bristles carried on an expandible ring frictionally held between pins projecting from the clamping members 19. The drive is made reversible so that short lengths of pencil can be sharpened and fed backwardly out of the machine.