Patent GB-344036-A (GB)
Title: Improvements in sewing machines
IPC: D05B3/06
Filed: 1929-11-28
Abstract: 344,036. Sewing- machines. SPIRELLA CO. OF GREAT BRITAIN, Ltd. and SIMMONDS, F. E. DE LA S., 201, Icknield Way, both in Letchworth, Hertfordshire. Nov. 28, 1929, No. 36563. Class 112.] Buttonhole sewing-machines; needles, vibrating laterally.-A sewing- machine is provided with means for effecting a barring-off operation at any point of the seam by jogging the needle and retarding the feed, without involving a n y special manipulation of the material being sewn. In the form shown, the machine sews an ordinary seam till the control knob 45 is depressed. When this occurs, a lever 23 is tilted about its pivot 90 against the spring 24 by the levers 44, 41, 40 till a pin 22 on the clutch lever 14 is freed from a recess in the lever 23, whereupon the lever 14 is moved about its pivot 15 under the influence of the spring 20 to the position shown in Fig. 4, and a sliding member 13 is moved along the countershaft 6 intc a position where its teeth are brought into driving engagement with the teeth of a member 28. The member comprising the cams 28, 30 and the part 29 are thus caused to rotate with the shaft 6. During this rotation, the pin 22 on the lever 14 rests on the upper edge of the lever 23 behind a recess and the lever is retained in the position shown in Fig. 4. The rotation of the cams causes the following mechanism to form a row of barring-off stitches, a short row of stitches parallel to the normal stitching line, a second row of barring-off stitches and an automatic return to normal stitching. A lever 47, pivoted to the casing, carries a roller 48 co-operating with the cam 30 under the influence of a spring 49. The free end of the lever 47 is pivoted to a link 51 engaging an arcuate member 54 carried by a stud 55 provided with a crank arm and a nut which engages a reversing screw 58 fast on the main shaft 2. The crank arm, stud 35 and member 54 are thus continuously rocked backwards and forwards as the machine is worked. The pin 52 passes through an elongated slot 59 in the bar 60 which is connected at one end through a ball point 61 with a forwardly extending lug 62 on a guide 63 for the needle bar 5, Fig. 2, this guide being arranged in known manner for rocking about a vertical axis 64 to move the needle bar from position 65 to position 65<1>. At the other end of the bar 60 is a link 66 pivoted to a lever 67 carrying a roller 69 co-operating with the cam 28. During normal st.tching, the parts remain in the position shown in Fig. 1, but when the clutch member 13 is moved by the control knob 45 and the cams 30, 28 rotate, the cam 30 depresses the lever 47 to draw down the link 51 to move the pin 52 to a position where it is no longer concentric with the pivot 55, so that the bar 60 is moved to-and-fro to jog the needle, so effecting a series of sidewise or barring-off stitches. When the requisite number have been made, the bar 60 is held stationary by the roller 69 and the high face of the cam 28, to produce a few stitches parallel to the normal stitching line. The conformation of the cam faces 30, 28 again enables the bar 60 to be vibrated, to produce a second set of barring stitches after which the rollers 48, 69 and cams 30, 28 cause normal stitching to recommence. The rate of feed is retarded to enable the barring-off stitches to lie close to each other by connecting the feed speed-adjusting spindle 75 to the lever 47 by links 77, 78, 76, 80. When the lever 47 is depressed to commence the barring-off operation, the rate of feed is automatically reduced.