GB1156211A - Improvements in or relating to Sewing Mechanisms incorporating Rotary Hooks - Google Patents

Abstract

1,156,211. Sewing machines. JANOME SEWING MACHINE CO. Ltd. 15 July, 1966 [17 July, 1965], No. 32035/66. Heading DIG. In a sewing machine comprising a shuttle body having a bulged rear wall formed with two apertures receiving respective lugs projecting from a rotary shuttle driver, the rotary axes of the shuttle body and driver being offset from one another whereby the lugs drivingly engage alternately with the respective apertures during one revolution of the driver, one aperture is so shaped and positioned in said end wall and the associated lug is so shaped that the side of the expanding needle thread loop sweeping across said end wall drops into the gap between said one aperture and associated lug so as to extend taut across said one aperture and is axially clear of the associated dog. The arrangements described in the present specification are modifications of the arrangements described in Specification 1,125,808. A shuttle body 1 has a circumferential bearing rib 12 with a cut-away portion 11 provided at one end with a loop-seizing beak 16. Projecting forwardly from rib 12 is an inclined wall 13 housing a cam-shaped annular edge 13a adapted to shift the lower thread out of the path of the needle. At the junction of rib 12 and wall 13 is formed a needle-passing slot 18 opening into a notch 18' formed in gap 11 to allow expansion of the upper thread loop away from the needle. Projecting rearwardly from rib 12 is a bulged wall 14 which carries a forwardly-projecting bobbin-supporting post 19 and which is formed with diametrically-opposed apertures 15, 15'. Aperture 15' is rectangular and is relatively long and narrow. Aperture 15 is relatively short and broad, and has an inclined edge 10. Shuttle body 1 is journalled about an axis 0-0. A driven shaft 32, journalled about an axis 0'-0' horizontally offset from axis 0-0 by an amount e, carries shuttle-driving lugs 33, 34 projecting into the aperture 15' and 15 respectively. The arrangement is thereby such that the driving lug situated to the left of a vertical line passing through axis 0'-0' drives the shuttle, when the other lug is spaced from its aperture The slope of edge 10 and that of the adjacent driving edge 36 of lug 34 is such that when lug 34 passes to the right of said vertical line and edge 36 separates from edge 10, the side of the needle thread loop engaging wall 14 and being stretched between beak 16 and the throat plate 61 becomes aligned with edges 10, 36, and passes across the radial ends 10' of aperture and axially clear of the nose of lug 34. During continued rotation and when lug 33 passes to the right of said vertical line, the action of the thread take up draws the needle thread loop through the gap between lug 33 and aperture 15'. In a modification in which a single shuttle co-operates with a pair of needles spaced apart in a direction at right angles to the direction of feed, cam edge 13a is modified, Figs. 13 to 15, to reduce the tension on the lower thread when the stitches are about to be set, for preventing thread breakage. In a further modification, Figs. 16, 17, a projecting rib (20) is provided in gap 11 to prevent re-catching of the thread loop by beak 16.