GB1024788A - Improvements in or relating to sewing machines - Google Patents

Abstract

1,024,788. Buttonhole-sewing-machines. NECCHI S.p.A. March 20, 1963 [April 4,1962], No. 11003/63. Heading D1G. Starting and stopping. A sewing-machine comprises cams for operating a lever 99 connected to a belt shifting lever 25 movable into positions a, b and c corresponding to a high speed, a low speed or the stopping of the machine, a speed controlling lever 94 operated by the cam and provided with steps 96-98, a spring 102 engaging the tooth 100 of the first lever in respective one of the steps so that the position of the belt shifting lever depends on which of the steps is engaged by the tooth. At the start of button-holing the arm 99 of the lever engages step 96 of the lever 94 and the belts engage pulleys 21, 22 and the machine runs at high speed. Towards the end of the button holing operation cam 69 displaces lever 94 to allow arm 99 to abut step 97 to shift the belts to engage pulleys 22, 23 and drive the machine at slow speed. Further movement of lever 94 by the cam 69 allows arm 99 to move into recess 98 to disengage the belt drive, a mechanical locking system then stopping the machine with the needle raised, while cam 69 rotates to present its low surface to the lever 94. To start a new button hole a treadle operated lever 106 is operated to swing back the lever 25, when arm 99 engages recess 96 again. A lever 122 may be manually operated at any time to run the machine first at slow speed and then, if required, stop it, in that particular order, independently of cam 69, by the engagement of a pin 117 with cam faces at either side of a notch 110 in the lever 94 to swing the latter to present the appropriate recess to the arm 99. Needles moving laterally (Figs. 2, 3 and 6, not shown) The needle bar gate 20 pivoted at 128 to the arm 2 is oscillated by a crank 131 on a shaft 132 connected by a crank 133 to a forked rod 134. The rod 134 embraces an eccentric 44 on a shaft 42 driven from the arm shaft 17, the lower end of the rod being engaged in a movable slide 137 pivoted at 138 to an arm 139 of a lever 140. The lever 140 is movable by the follower 144 of a cam 70 of a bank of cams 68-74 to vary the field of oscillation of the needle bar gate. A lever 154 may rest against a stop or be positioned by the followers of cams 72, 71 to rotate the pivot 138 of slide 138 to make the amplitude of the gate oscillation zero, medium or large respectively. The cams 68-74 are driven from the shaft 17 by way of interchangeable gears 49, 51. Frames:- The foot of the column 4 connecting the machine base to the arm is offset to provide a recess permitting the material to be sewn to move freely in the direction of the arm. Feed by presser foot (Fig. 1, not shown) The interchangeable presser foot 91 is carried at one end of a lever 89 pivoted to a block 87 reciprocable in a guide 88 by a rod 80 having one end adjustably connected at a slot 78 to one arm of a bell crank lever 76 oscillated by the groove cam 69. The presser foot can be raised, by the operation of a lever 224 (see Fig. 6, not shown) to cause stop 231 to abut and depress an end of lever 89. A lever 222 prevents the depression of lever 224 except when the machine is stopped, and prevents the starting of the machine when the foot is raised. Buttonhole machines, cutting threads (Figs. 6, 7, not shown) The buttonhole piercing knife 173 is operated through linkage 197, 196, 194, 204, by the connection of a notch 205 in member 192 with a pin on a swinging member 200 oscillated by a grooved cam 45 on the shaft 42. The connection is achieved by a lever 176 (Fig. 6) moved by cam 74 to displace a rod 177 against the action of a spring 180 allowing the collar 187 to shift under the end of the member 192. As the rod 177 returns after the passage of the lobe of cam 74 the end of member 192 drops between the collar and the ring 188, notch 205 connects with member 200 and the knife makes a single stroke. On the return stroke the inclined end of the member 192 rides up on the ring 188 to disconnect the knife drive. The cam phasing prevents the operation of the knife until the machine is running at maximum speed. Further, to prevent knife operation when the machine is at rest a lever 206 is connected to the belt shifting lever 25 by linkwork 210-214 and then prevents the member dropping into engagement with the member 200. The lever 206 may also be operated manually to avoid the use of the knife at the end of the buttonhole making cycle. Rotation of the lever 224 by a pedal operates a known knife 233 to cut and retain the top thread and a further knife, not shown, which cuts and retains the lower thread; the latter draws the cut end of the upper thread towards the undersurface of the material. Releasing thread tension (Fig. 1, not shown) The cam 73 operates levers 170,171 to open the tension discs 172 when the buttonhole is completed. Connecting upper and lower shafts, lubricating reservoirs (Fig. 2, not shown) The gears connecting the shaft 17 to the lower shaft 37 to the shaft 42 and to the cam shaft are disposed in oil reservoir cups 39 and 5.