Patent GB-1274979-A (GB)
IPC: D05B19/00
Filed: 1970-05-19
Abstract: 1,274,979. Sewing-machines. SINGER CO. 19 May, 1970 [26 May, 1969], No. 24064/70. Heading D1G. An exchangeable pattern cam unit for a sewing machine comprises a driven cam shaft with a cam reception seat and unit having a hub portion accomodated on the seat and to be brought into and out of rotational interlocked relation with the cam shaft, selectively engagable clutch means in the hub portion and on the cam disk including a clutch controlling element on the cam disk the disk and hub being relatively rotatable on disengagement of the clutch and a manually rotatable handle engageable with the cam disk member. Pattern cam unit. The exchangeable pattern cam unit (Fig. 16) comprises a reception seat 220 with a spring clip 222 to engage the hub of the interchangable pattern cam unit. A pin 221 engages a slot 232 in the hub 230 which is provided with teeth 235 engageable by a pawl 253 mounted on bell crank lever 250. The levers 250, 251 have holes which are located over pegs 248, 249 to provide pivoting movement. Holes 272, 273 in a knob 270 locate over pegs 248, 249 and a pin 275 downwardly projecting from the knob engages an arm 255 on the bell crank lever 250 so that manual rotation of knob 270, permitted by lost motion provided by the enlarged holes 272, 273 disengages the pawl from the teeth 235 and stops rotation of pattern wheels 241, 242 whilst allowing continued movement of pattern wheel 74. The arms 254, 259 project through the annulus 240 for automatic actuation during button holing (Fig. 14). Button hole control (Fig. 14). A thumb wheel 133 can be turned so that a follower 285 can locate in any one of recesses 281- 283 each recess corresponding to a different position of an arm 295 which is rotatable about an axis 292. The arm 295 has a notched end which engages arms 254, 259 for automatic control during button holing. When the follower 285 engages notch 281 the arm 295 is elevated to a position above both arms 254, 259 and all the cam units will rotate together as the pawl 253 is engaged. In either of the other positions the cam will rotate one half turn before being stopped by release of the pawl 253 by arm 295 and each half turn of the cam is arranged to provide the barring and zig-zag stitches for one half of the buttonhole. Needle position control (Fig. 10). The needle position is controlled by a wheel 130 which through a link 135 moves a cam 136 longitudinally. The surfaces which act on a follower 61 determine the left, right and central positions of the needle and at the fourth discrete position of the wheel a pin 158 ride up on top of a cam surface 159 so that a further follower gauged with the follower 61 is raised into a position where it engages an interchangable cam surface in such a way that the needle position is influenced by the cam. Stitch width control (Fig. 11). Stitch width is controlled by a wheel 131 acting on a three armed lever 163. Stops 167, 168 are provided to act on arms 166, 165 respectively to determine minimum and maximum stitch widths and a spherical recess in arm 165 carries the spherical end of lever 51 which controls the stitching operation. Cam selection control (Fig. 13). Control wheel 132 controls the position of cam follower 59 which may be located either adjacent cam 74 for normal zig-zag operation of the machine or raised to a position adjacent one of the interchangable cams thereabove for button holing operations. The wheel is mounted on a pivoted lever so that it can be pushed inwardly to disengage arm 199 from one of slots 202 provided in shaft 60 about which the follower 59 pivots. Rotation of wheel 132 causes rod 193 to rotate about its axis and moves the arm 199 upwardly or downwardly. When the wheel 132 is released the arm 199 engages in the newly selected slot 202 and is thus held in position. Stitch length control (Fig. 9). The stitch length regulator shaft 38 has a bell crank 84 secured thereto beneath the sewing machine standard 12. One arm 85 is blade shaped and the other arm 86 carries a crank pin 87 which transmits manual control of the stitch length. An annular cam groove 95 is tracked by a follower pin 96 carried on a link 97. As a dial 92, carrying the cam groove 95, is turned the link 97 controls the stitch length regulator shaft 38.