Patent GB-191213877-A (GB)
Title: Improvements in or relating to Buttonhole-sewing Machines.
Inventor: BOULT ALFRED JULIUS
IPC: B29C73/10
Filed: 1912-06-13
Granted: 1913-07-14
Abstract: 13,877. Boult, A. J., [United Shoe Machinery Co.]. June 13. Button-hole sewing-machines; needles, driving; governing needle thread; governing under thread.-The invention relates to means for driving the upper and under needles and for governing the needle thread. The straight upper needle is at first moved slowly towards the co-operating curved under needle and is then moved rapidly through the remainder of its cycle. The stitchforming devices comprise a straight upper needle 61 passing through the fabric, a curved eye - pointed under-needle 62 passing through the button-hole slit, and a looper 63. During the sewing operation, in order to form the stitches round the button - hole, the stitchforming mechanism is rotated once, the upper needle being mounted in a rotary sleeve 66, and the under - needle and looper in a rotary turret 88. The sleeve 66 and turret 88 are rotated by chains 70, 123 from a shaft 73 which receives its motion from the gear-wheel 60 by the link - and - cam device shown in Fig. 8. The shaft 73 is connected by a link 127 with a lever 125 pivoted to the wheel 60 at 126 and engaging by a roll 129 a camgroove 130 in stationary cam - plate. The upper needle 61 is mounted eccentrically in a bar 65 which is reciprocated from a shaft 75 by a crank and link 74, 76. The shaft 75 is rotated to give a comparatively slow advance and a quick return to the needle by a connexion with the driving - shaft 78, with which it is out of alinement comprising a crank-pin 79 engaging a radial slot 81, Figs. 1 and 4. The shaft 78 is connected with the main driving - shaft 84 by gearing 82. The upper thread passes through a tension 102, a pull - off device 101, Fig. 1. down through the hollow needle bar, and through a light tension 100 to the eye. A thread-engaging device for determining the slack given up by the needle comprises an adjustable sleeve 67 into which the needle bar passes at the inner end of its stroke. The tension 102 is released periodically by a rod 202 acted on by a cam on the wheel 31. The thread is drawn off the end of the under needle by a finger 101' reciprocated between guides 100 by the shaft 84. The under needle 62 is carried by an arm 85, Fig. 12, pivoted on the turret 88 at 86 and having a curved slot 93 engaged by a roll on an arm 89 mounted on a sleeve 90 on a pivot shaft 91. The sleeve 90 is rocked by an arm 94 connected by a link 95 with a lever 96 which is actuated by a link 98, Fig. 1, connected to a crank on the main driving shaft 84. The looper 63 is pivoted on one end of an arm 114, Fig. 11, mounted on a rock shaft 115, the other end of the arm being guided in stationary camslot 119, or by a pivoted link. The rock-shaft 115 is actuated by a link 117 connected to an arm 118 on the sleeve 90. The under thread t<1> passes to the needle 62 by way of the hollow link 95, a tension - device 106, and suitable guiding-eyes in the turret. The stay cord s also passes up the link 95, and in order to prevent twisting of the thread and cord, by the rotation of the turret, the supplying-devices, Fig. 4, are rotated in the opposite direction. The cord reel 140 and thread guide 145 are rotated together by a chain driven by a shaft 134, Figs. 4 and 7. The switch-forming mechanism is driven by a pulley 150, Fig. 1, which contains a friction clutch for coupling it to the shaft 84. The clutch is put in when a pinion 157 is rotated by a rack 158, the pinion having cam means for moving it endways when rotated. The rack 158 is actuated by a spring 163 and a cam on the face of the wheel 31. The shaft 84 is stopped in a determined position by the engagement of a cam 166, Fig. 1, with a conical roll 168 on an arm 167 which is actuated by a spring and a cam on the wheel 31. The wheel 60 which imparts the rotary movements to the stitchforming mechanism is driven by a shaft 134. Fig. 4, to the upper end of which is connected a shaft 135 by a universal joint. This shaft carries a gear 136 driven from the shaft 84, and by changing the gear 136, the number of stitches round the button-hole may be readily altered. The cam-carrying gear-wheel 31 is rotated independently of the stitch-forming mechanism driving the cutting or like operation, but is rotated from the same source during the stitching operation. The gear 31 is driven by a pinion 177, Fig. 4, on the sleeve loose on the shaft 134. The sleeve is adapted to be clutched for the cutting operation to a gear 183 running loose on the shaft 134', and driven by a continuously running shaft 186, and the pinion 133 by a spring-pressed pin 180, for the stitching operation. The clutching is controlled by an arm 188 which is actuated through a gear sector 198 by a cam-groove in the wheel 31. The clutching is also controlled by the starting-finger 194, which engages a spring-pressed stop arm 191. The frame 1 carrying the operative parts is connected to the base 2 by trunnions 3, Fig. 1, to facilitate inspection. The work clamp comprises a carriage 5, Figs. 4 and 7, having worksupporting plates 4 pivoted to it at 6 so that they are separated to stretch the work by a stationary cam when the carriage is advanced to the sewing position. The clamps 7, Figs. 10 and 12, are mounted on arms 8 pivoted on the plates 4, and are closed by a lever 33, 37 which is actuated by a projection 39 on the cutter-arm 29. The clamp is locked in its closed position during the sewing operation by the engagement of a latch 44 with a spring-pressed one-way latch 45, 46 on the frame as shown in Fig. 12. The backward movement of the clamp carriage at the end of the sewing-operation releases the latch 44, and a coil spring acts on the arm 33 to open the clamp. The clamp carriage 5 has bearings 50, 51, Fig. 7, on the frame, and is moved longitudinally by a cam-groove 53 in a gear-wheel 31, Fig. 10, engaging a roll on a stud 54. The pivot-block of the stud slides in a slot in the frame. The carriage is swung laterally by a lever 57 actuated by a cam-groove on the face of a gear-wheel 60, Fig. 4, and connected to the carriage by a block 58 engaging a slot 59. The cutting-mechanism comprises a supported lower block 22, and a cutter blade 24 carried by an arm 25 mounted on a yoke 26 pivoted at 28, Fig. 1. The yoke is rocked to actuate the cutter by a bell-crank-lever 29 pivoted on its rear side and having an arm engaging a cam 30 on the gear-wheel 31 and the other arm engaging an adjustable set-screw 32 on the yoke. The constructional arrangements may be modified. Specification 3293/13 is referred to.