Patent GB-641083-A (GB)
Title: Improvements in or relating to a knife sharpening device on a cloth cutting machine
IPC: B24B3/36
Filed: 1947-01-21
Abstract: 641,083. Cutting machines. RUBENSTEIN BROS. CO. Jan. 21, 1947, No. 1915. Convention date, Jan. 23, 1946. [Class 31 (ii)] [Also in Group XXIII] In a cloth-cutting machine having a motordriven reciprocating straight knife a knife sharpening device comprises a rod having a helical double-threaded keyway adapted for rotation and reciprocation parallel to the knife, a follower adapted to engage the thread on the rod for causing the reciprocation of the rod on its rotation, a carriage mounted on the rod, rotatable abrasive means mounted on the carriage and rotatable by the rod, a driven element connected to the rod, a driving element connected to the motor, a friction clutch wheel between the driving and -driven elements, the rod being driven by the motor through the clutch wheel to cause outward and return sharpening movements of the abrasive means, manual means for engaging the clutch wheel and means operable by contact with the carriage in its return movement for disengagement of the clutch wheel. In the example shown, the operation of the knife sharpening device is initiated by the manual engagement of the clutch wheel and the carriage is reciprocated the length of the knife and the abrasive means are simultaneously rotated, the action being automatically stopped as the carriage completes its upward movement, the abrasive means being stopped and separated from the knife. The cloth cutting machine comprises a base-plate 1, a presser foot 7, the knife 9 reciprocating in a standard 4 by means of a crank 10 driven by the motor 8, and a guiding handle 6. A housing 11 rotatably carries a sleeve 44 which carries the friction wheel 80 to drive a coaxial worm 81. The friction wheel 80 can be engaged with the driving shaft of the motor 8 by rotation of the sleeve 44, and the worm 81 drives a meshed gear 82 carried by a sleeve 42 which is keyed to the rod 40. On the periphery of the rod 40 is the double helical threaded keyway in which runs the follower key 41 mounted on the housing 11 in order to reciprocate the shaft 40 the length of the knife 9 as it is rotated. On the lower end of the rod 40 is a gear 30 in the carriage 43 on which are mounted two spring-urged arms 21, 22, Fig. 13, on each of which is mounted an abrasive wheel 20 of emery or suitable material. The abrasive wheels are driven in opposite directions by a gear train from the gear 30. Secured to the carriage 43, Fig. 8, is a guide frame 90 carrying rollers 92, 93 which run on the standard 4. When the carriage 43 is in the position shown in Fig. 2, a wedge-shaped peg 50 secured to the housing 11 forces the arms 21, 22 off the knife 9 by projecting through an aperture 51 in the carriage 43. To enable the sleeve 44 to be rotated in order that the friction wheel 80 should contact the shaft of the motor 8, an arm 58 projects from a bracket 45 on the sleeve. The arm 58 carries a spring-loaded sleeve 55 having a collar 57. The pointed end of an automatic stop-rod 70, which is spring-loaded, engages the collar 57. The sleeve 55 has first to be moved inwardly to enable the collar 57 to clear the rod 70 to enable the arm 58 to be moved from the drive-disengaged position A, Fig. 4, to the position B engaging the wheel 80 with the motor drive. A spring 60, Fig. 2, urges the sleeve 44 to the driving position. When the collar 57 is disengaged from the rod 70, the rod 70 moves downwardly under the action of a spring 71 to its lower limit. On the upward movement of the carriage 43 to complete the sharpening cycle on the knife 9, the carriage 43 engages the lower end of the rod 70 which forces the collar 57 and the arm 58 back into the position A. If the presser foot 7 is not fully lowered, a rod 75 projects upwardly from a bracket 12 on the housing 11 and moves a pivoted arm 76, Fig. 2, which engages the collar 57, preventing any movement of the sleeve 55 and consequently engagement of the frictionwheel 80 with the motor shaft.