Patent GB-1120988-A (GB)
Title: A method of finishing buttonholes sewn in an automatic sewing machine and device for carrying out said method
Inventor: JINDRICH EMIL
IPC: D05B3/08
Filed: 1967-01-16
Abstract: 1,120,988. Sewing machines. ELITEXZAVODY TEXTILNIHO STROJIRENSTVI, GENERALNI REDITELSTVI. 16 Jan., 1967 [14 Jan., 1966], No. 2155/67. Heading DIG. [Also in Division F2] A buttonhole sewing machine comprises a work-supporting table, means for holding the work on said table, means for moving said table both longitudinally and laterally relative to stitch-forming means, and means for rotating the stitch-forming means, the machine being adapted, after completing the straight longitudinal part of a buttonhole, to sew several transverse end stitches and to cover the latter with a system of further stitches. A shaft 36 may be coupled by a clutch 39 to a pulley 35 driven by a belt 34 from an electric motor. A worm 21 on shaft 36 drives a gear 19 journalled on a shaft 20. A cam groove 18 in gear 19 co-operates with a roller 17 on the lower end of a shaft 13 which is rigid intermediately at 14 with a work-supporting table 9 and is slidable at its upper end in a groove formed in the machine frame longitudinally of table 9. Rotation of gear 19 thereby serves to reciprocate table 9 longitudinally in the directions A, B. Shaft 36 is coupled by gearing 40, 41 to a shaft 42 carrying a cam disc 30 having a cam groove engaging a follower 28 on a crank arm 24 rigid with a pivot 25. A pin 22 on arm 24 engages a groove 23 formed longitudinally in table 9, whereby rotation of disc 30 serves to oscillate table 9 about the axis of shaft 13 in the transverse directions P, R. The work is held on table 9 by presser feet 10. A shaft 49 may be coupled by a uni-directional clutch 52 to a pulley 48 driven by a belt 47 from the electric motor. Connections from shaft 49 impart axial and transverse movements to the needle bar 4 for producing zig zag stitching. Shaft 49 is coupled by gearing 88, 89 to shaft 20, and the latter is coupled by gearing 92, 94 to a shaft 95 driving the looptaker 5. An eccentric 72 on shaft 49 is embraced by a fork 73 on one arm of a two-armed lever 74 pivoted at 76 to one end of a link 77. The other end of the latter is pivoted at 78 to one end of a link 79 pivoted at its other end at 80 to a crank arm 81 coupled by a uni-directional clutch 45 to shaft 36. Link 77 is pivoted intermediately at 82 to a block 83 slidable in a fork 84 carried by a two-armed lever 85, 87 pivoted at 86. Arm 87 is normally biased by a spring 112 against an abutment 114 on a lever 115 pivoted at 116. The fork 84 is thereby positioned at an angle to link 77, whereby on rotation of shaft 49, pivot 78 swings in the directions C, D to oscillate crank arm 81 for rotating shaft 36 intermittently if clutch 39 is disengaged. A disc 121, journalled on a fixed pin (122), Fig. 3, journals a ring (138) coupled by a uni-directional clutch to a disc (127) journalled on pin (122). An eccentric 93 on shaft 20 is connected by a strap 123 and pitman 124 to a pin 125 on disc (127) for oscillating the latter. A pin 142, pivoted on disc 121, has a nose 143 normally biased by a spring (145) to engage one arm of a twoarmed lever 146 pivoted at 147, the other arm being held against a fixed abutment 167 by the end 148 of arm 85 of lever 85, 87. Pin 142 is formed intermediately with a notch such that, when nose 143 engages lever 146, the inner surface of said notch is co-incident with the engaging surfaces of disc 121 and ring (138), while pin 142, when free to turn under the bias of spring (145), enters one of a series of notches in the inner surface of ring (138) to couple the latter to disc 121, which is thereby rotated intermittently. A cam groove 149 in disc 121 co-operates with a follower 156 on a lever arm 157 rigid with pivot 25. Follower 156 is normally disposed in a recess 150 and is then engaged by the forked end 160 of one arm of a double-armed lever 158 pivoted at 159, the other arm carrying a follower 161 co-operating with a cam 46 on shaft 42. A cam 151, rigid with disc 121, co-operates with a follower 154 on one arm 155 of a double-armed lever pivoted at 99, the other arm 98 being coupled by a link 102 with a crank arm 104 on a shaft 105. A member 97, rigid with arm 98, carries a follower 96 co-operating with a cam groove formed in gear 19. Shaft 105 carries gear segments 108, 109 meshing with gears 110, 111 respectively, whereby, on rotation of shaft 105 the stitch-forming elements 4, 5 are rotated about their axes by gears 110, 111 respectively. A cam lobe 152 or disc 121 is adapted, at the end of a buttonhole-stitching cycle, to engage a follower 163 on one arm of a double-armed lever 164 pivoted at 165. The other arm is connected by a link 71 to a lever 66 pivoted at 67. Lever 66 is thereby swung, against the bias of a spring 68, to disengage an abutment 69 thereon from the end of one arm 56 of a three-armed lever pivoted at 57. A spring 58 acting on arm 56 thereby swings said lever to engage an abutment 54 on a second arm 55 with a lug 53 associated with clutch 52 to uncouple shaft 49 from pulley 48. An abutment 61 on the third arm also engages a cam plate 62 on table 9, the latter then being in its extreme right hand position. To sew a buttonhole, after the work is positioned on table 9 and clamped thereon by the feet 10, a starting lever is actuated for coupling shaft 36 to pulley 35 via clutch 39. Initial rotation of gear 19 effects no movement of table 9 but serves to actuate the buttonhole-cutting mechanism. During initial longitudinal movement of table 9 in direction A, plate 62 co-operates with abutment 61 to swing the three-armed lever for disengaging abutment 54 from lug 53 and for engaging arm 56 with abutment 69. Clutch 39 is simultaneously actuated for uncoupling shaft 36 from pulley 35. Sewing of the straight portion of the far side of the buttonhole then starts at point II and continues until the commencement of the eyelet end is reached, when cam 46 co-operates with follower 161 to swing lever 158 for disengaging fork 160 from pin 156, while followers 28 and 96 co-operate with their respective cam grooves for respectively turning table 9 and the stitch-forming elements 4, 5. At the completion of the eyelet end, fork 160 re-engages pin 156 and table 9 moves longitudinally rightwards in direction B for sewing the straight portion of the near side of the buttonhole. When table 9 approaches its extreme right hand position, a pawl 64, pivoted at 63 to plate 62 and held vertically by the engagement of a pin 65 thereon with the upper edge of plate 62, engages lever 115 which thereby swings, against the bias of a spring 117, to disengage abutment 114 from arm 87. Spring 112 thereby turns arm 87 into engagement with an abutment on one arm of a double-armed lever 118, to align fork 84 with link 77, whereby pivot 78 moves axially of link 77 in the directions M, N and link 79 merely pivots about point 80 without oscillating arm 81. Longitudinal movement of table 9 thus ceases at position VI of the buttonhole, while operation of the stitch-forming elements 4, 5 continues. Abutment 148 on arm 85 simultaneously releases lever 146, whereby pin 142 is able to turn for coupling disc 121 to intermittently-rotating ring (138). A pin 153 on disc 121 then co-acts with lever 158 to disengage fork 160 from pin 156, and the latter co-operates with cam groove 149 for imparting transverse movement to table 9. Transverse, reinforcing end stitches 1 to 7 are thereby sewn. Cam 151 progressively turns the elements 4, 5 through 90 degrees, whereby the final forward stitch 8 is formed parallel to the axis of the buttonhole, and the return barring stitches are positioned over the reinforcing stitches in a direction at right angles to the axis of the buttonhole. When the final position VIII is reached, cam lobe 152 cooperates with follower 163 for uncoupling shaft 49 from pulley 48, whereby stitching ceases. Shaft 36 is simultaneously coupled to pulley 35, whereby table 9 again moves longitudinally and engages lever 118. The abutment 120 thereby shifts arm 87 to re-engage the latter with abutment 114, while the abutment 148 on arm 85 re-engages lever 146 with abutment 167 to uncouple disc 121 from ring (138). Table 9 in its extreme right hand position actuates a limit switch for uncoupling shaft 36 from pulley 35.