GB876523A - Improvements in or relating to sewing machines for automatically producing stitches forming various patterns - Google Patents

Abstract

876,523. Stencil switches. MEFINA S.A. Oct. 22, 1958 [Nov. 14, 1957], No. 33790/58. Class 38 (5). [Also in Groups VII, XXIV and XXXVIII] In a sewing-machine in which the needle bar and feed movements are governed, during alternate halves of each revolution of a drive shaft, by control means acting in accordance with information transmitted from a programme controller by a programme reading arrangement, the programme controller is driven intermittently, and the reading arrangement comprises fixed and movable groups of readers adapted respectively to read the programme controller when the latter is stationary and in motion, reading taking place when no relative movement occurs between the programme controller and the readers. A casing 13, fixed at one end to the sewing- machine, journals a drive shaft 11 and carries at the other end a programme controller in the form of a disc 1 formed on its inner surface with ten concentric rows of depressions 2. Disc 1 is arranged to be rotated unidirectionally a constant amount during half of each revolution of shaft 11 and to remain stationary during the other half. Engaged with the upper half of disc 1 is a half-disc 24 formed with five holes 27 to 31 situated at radial distances equal to the respective radii of the five inner rows of depressions 2. Each of said holes contains a ball 32 which functions as a reader and which is biased into engagement with disc 1 by the spring- loaded plunger 33 of a microswitch 34 rigid with the half-disc 24. The latter is arranged to rotate with disc 1, when one or other of the balls 32 enters a depression 2 to close the corresponding switch and thereby transmit a signal to means for controlling the movements of the needle bar. Half-disc 24 is also arranged to rotate in the reverse direction to its initial position while disc 1 is stationary, when none of the balls 32 lies in a depression and no signal reaches the feed bar control means. Engaged with the lower half of disc 1 is a fixed half-disc 36 formed with five holes 38 to 42 situated at radial distances equal to the respective radii of the five outer rows of depressions 2. Each of said holes contains a ball 43 which functions as a reader and which is biased into engagement with disc 1 by the spring-loaded plunger 44 of a microswitch 45 rigid with half-disc 36. The arrangement is such that when disc 1 is stationary, one or other of the balls 43 lies in a depression 2 for closing the associated microswitch to transmit a signal to means for controlling the work feed, while none of the balls 43 lies in a depression 2 when disc 1 is moving. An eccentric 14 on shaft 11 engages the sides of a vertical slot formed in a vertical lever 18, and an eccentric 15 on shaft 11 engages the sides of a horizontal slot in lever 18. The upper end of the latter carries a pin 19 and the lower end carries a pin 20 which permanently engages the sides of a vertical slot 46 formed in a wall 13b of casing 13. The arrangement is such that on rotation of shaft 11, pin 20 reciprocates in slot 46, while pin 19 traces an elliptical path. Journalled on the inner end of shaft 11 is a hub 6 to the outer end of which disc 1 is secured by means of a knurled-headed screw 8 and also by means of pins 9 and 10 which pass through holes 4, 5 in disc 1 and holes 48, 49 in hub 6. The inner end of the latter carries a disc 7 which abuts lever 18, and the periphery of which is formed with parallel-sided notches spaced apart at angular distances equal to the smallest angle separating two adjacent depressions 2 in the same concentric row. A sleeve 23, journalled on hub 6, carries at its inner end an arm 22 formed with a radial slot 21 the sides of which permanently engage pin 19. The outer end of sleeve 23 carries the half-disc 24 and the latter is movably anchored to the casing 13 by screws 25 which pass freely through slots 26 in disc 24. Half-disc 36 is carried by a sleeve 35 surrounding sleeve 23, and is rigidly fixed to casing 13 by screws 37. Pin 19, when situated in the upper portion of its elliptical path, will be free from disc 7 and by its engagement with slot 21 will return the half-disc 24 its initial position, while pin 20 will then be engaged with disc 7 to hold disc 1 stationary. When pin 19 is situated in the lower portion of its elliptical path, pin 20 is disengaged from disc 7 and pin 19 is engaged with both the latter and with slot 21 to rotate disc 1 and half-disc 24 together. It is stated that, as an alternative to the depressions 2, disc 1 could include conducting and insulating areas, when the readers 32 and 43 would be electrical contacts.