Patent GB-896274-A (GB)
Title: Rotation restraining means and needle guard for sewing machine loop taker
IPC: D05B55/06
Filed: 1960-08-16
Abstract: 896,274. Sewing machines. FAIRWEATHER, H. G. C. (Singer Manufacturing Co.) Aug. 16, 1960, No. 28342/60, Class 112. A sewing machine comprises a looptaker having a shaft journalled in a bushing turnable in the machine frame and formed with a flange on which is mounted on element serving to hold a bobbin carrier in position and/or as a needle guard, means being provided for securing the bushing in an angular position such that said element has a predetermined position relative to the path of travel of the loop-seizing beak both radially of and angularly about the axis of said shaft. Stitch-forming. The needle bar 41 of a zig-zag sewing machine co-operates with a hook which oscillates about a vertical axis and which comprises a ring 58 having a flat upper flange 60 formed with a circular opening 61. Ring 58 is connected by a radial web 59 to a shaft 51 which is journalled in a fixed bushing 96. A crank 53, fixed to shaft 51, is connected by a link 54 to one arm 55 of a bell crank lever, the other arm 56 of which is connected by a link 57 to a crank pin or a disc 29 fixed to a vertical shaft 31 which is rotated by gearing from the arm shaft of the machine. Ring 58 is formed with an inclined slot 62 which defines a loop-seizing beak 63. A bobbin carrier 65 has an upstanding cylindrical wall 66 defining a recess to receive a bobbin, the latter resting on a horizontal flange 68 at the bottom of the recess. A flange 70 extending horizontally from wall 66 has an arcuatelyshaped edge portion 75 formed with a groove adapted to receive the inner circular edge of flange 60. The edge portion 93 of flange 70 opposite the arcuate portion is substantially diametrical with respect to the opening 61. Flange 70 is formed adjacent the point of loop seizure with a notch 82, and is formed adjacent the po'nt of loop cast-off with an inclined edge portion 80 adapted to receive the cast off loop. The edge of flange 70 is formed adjacent the portion 80 with an abutment surface 81, and notch 82 is formed with a second abutment surface 85. A bobbin thread tensioning spring 86 is mounted on the wall 66. Extending horizontally from the upper end of sleeve 96 is a flange 95 formed with a groove 97. A bracket 94 is secured to flange 95 by a screw 99, the lower plain end 117 of which enters a dowel hole in the machine frame, and a depending lip 98 on bracket 94 enters the groove 97. A finger 101, rising from bracket 94, is adapted to engage the abutment surface 85 to prevent clockwise turning of the bobbin carrier. Bracket 94 is also formed with a horizontal flange 103 on which is pivotally mounted, by means of a screw 108, a spring abutment member 107. An aperture 110 in the latter normally engages a washer 109 secured adjustably to flange 103 by a screw 111. Member 107 is thereby held in a fixed position, when the end 113 of a finger 112 extending therefrom engages the abutment surface 81 to prevent anti-clockwise turning of the bobbin carrier. To release the latter, member 107 is lifted off the washer 109 and swung away from the bobbin carrier, end 113 then being lowered on to the outer end 106 of flange 103. Needle guards, stitch forming. On the flange 95 of the bushing 96 is an upstanding arm 114 which carries a needle guard 115 having outer and inner vertical surfaces which are concentric with the axis of the hook. The inner surface 116, which deflects the needle 41 inwardly when the latter descends, joins sloping surface 121 along a line L6, and the arrangement, it is stated, is such that needle thread loops of substantially equal size are formed at the point of loop seizure, irrespective of the position of the needle between extreme left and right hand positions L and R respectively. Surface 121 is so formed that line L6, between the positions L and R, is substantially parallel to a line L4 indicating the height of the needle eye 120 at loop seizure. Normally, loops formed at position R are smaller than the optimum size, and at position L are larger than the optimum size. Since, however, loop-formation on the loop-seizure side of the needle is prevented by the surface 116 until the needle eye has risen above the line L6, and since the needle eye then traverses a substantially constant distance before loop seizure occurs, the size of the loop at loop seizure will not vary substantially between the positions L and R. Specification 896,275 is referred to.