Patent GB-702431-A (GB)
Title: Improvements in or relating to article cutting apparatus
IPC: H01C17/24
Filed: 1952-02-01
Abstract: 702,431. Grinding helical grooves. WESTERN ELECTRIC CO., Inc. Feb. 1, 1952 [Feb. 9, 1951], No. 2739/52. Class 60 Article cutting apparatus comprises a cutter rotatable about a given axis, a rotatable chuck actuable to receive and grip articles one at a time, means for moving the cutter axially, means for rotating the chuck in timed relation with the axial movement of the cutter, means normally urging the chuck towards the cutter under a variable force, and means normally holding the chuck away from the cutter and actuable to release the chuck for lateral movement of the article under the said force into the cutter whereby a helical groove will be cut into the article. A helical groove is cut in the carbon coating 53 on a ceramic member 52 to form a resistor, by a cutting wheel 20, e.g. a diamond cutter. The wheel 20 and its driving motor 22 are mounted on a slide 25 movable so as to traverse the cutter 20 axially ; movement in one direction is effected by a spring 34 and in the opposite direction by a cam 35 on a cam shaft 45. Workpieces are fed successively through a feeding tube 51 to a feeding unit 55 where they are limited in their movement by an adjustable stop 56 ; the exit end of the tube 51 is supported by a stationary member 57 having a notch 59 disposed in alignment with the exit end of the tube. A feeding member 60, pivotally mounted on the member 57, has a notch 62 which is in alignment with the notch 59 when the feeding member is in the receiving position, as determined by an adjustable stop. The member 60 is movable to another position, as determined by a fixed stop, to locate the workpiece carried thereby in a position to be received by a chuck. The member 60 is oscillated by a cam 72 on the cam shaft 45. The mechanism for receiving the workpieces successively from the feeding unit 55 includes a turret-like structure supporting three equallyspaced chucks so that while one chuck is in the operating position, another chuck will be in the ejecting position and the third chuck will be in the receiving position. Each chuck shaft 76 is journalled in an arm 78 the inner end of which is pivotally supported at 80 between triangular shaped members 81. Each chuck is normally closed by a spring 93, and is opened by a cam 106 acting through a bell crank lever 100, 104 ; the cam 106 is oscillated by a cam 115 on the cam shaft 45. Each arm 78 carrying a chuck is urged outwardly about its pivot 80 by a spring 118, the force of which can be adjusted by a handwheel 119. To prevent this outward movement, except at the cutting station, a roller 89 carried on the chuck spindle runs on the inner surface of a circular member 126 having a notch 127. An annular member 130 has a notch 133 positioned to register with the notch 127 during a given interval of time ; the annular member 130 is operated by a cam 135 on the cam shaft 45. Resilient elements 145 serve as rests for the chuck units as they are forced inwardly by the members 126, 130. The triangular members 81 and parts carried thereby constitute a turret which is intermittently rotated by a Geneva mechanism, the operating shaft 153 of which is driven through gears 154, 155 from the cam shaft 45. A roller, adapted to engage notches in the Geneva mechanism, and operated by a cam 169 on the cam shaft 45, latches the turret against rocking motion during the intervals of rest and accurately locates the turret to ensure accurate positioning of the chucks with respect to the feeding unit and the cutting wheel. Each chuck unit is driven when in the operating position adjacent the cutting wheel 20. Each chuck spindle is driven through gears 87, 88 from a shaft 83 mounted in the turret coaxially with the pivot 80 and carrying a gear 86 which meshes, when the chuck is in the operating position, with a pinion 203 ; the pinion 203 is driven through one or other of two gear trains giving two alternative speeds. In operation, the workpieces 52 are received singly from the tube 51 ; that chuck which is at the receiving position is then opened by the cam 115 ; the workpiece is moved into the feeding position, to be received by the chuck, by the feeding element 60 operated by cam 72. The chuck at the receiving or loading position is allowed to close prior to indexing of the turret. The turret is then indexed to move the loaded chuck from the feeding position to the operating position ; at this time the cutting wheel is in its starting position. The cam 135 then operates the annular control member 130 to align the notches 133, 127, this permitting outward movement of the arm 78 by the spring 118, bringing the workpiece into contact with the cutting wheel. At this time the cam 35 operates to allow the spring. 34 to move the carriage supporting the cutting unit, whereby the cutting wheel traverses axially. As the chuck moves into the operating position, its gear 86 engages the gear 203 so that the chuck is rotated. At the termination of the cutting operation the cam 135 operates to move the chuck so as to bring the workpiece out of contact with the cutter. The turret is then indexed, the cutter meanwhile returning to it initial or starting position. After indexing, the finished workpiece is ejected into a receptacle 220.