GB641324A - Improvements in or relating to devices for use in sewing machines - Google Patents

Abstract

641,324. Sewing-machines. MAN-SEW CORPORATION. June 1, 1948, No. 14778. Convention date, June 7, 1947. Addition to 634,525. [Class 112] The zig-zag sewing mechanism of the parent Specification is modified to provide for progressive variation of the amplitude of vibration of the needle, either related or unrelated to the lateral shift of the field of vibration, and also to enable the amplitude-variation and the fieldshift to be suspended when desired..The surface cord guide finger is oscillated by the needle-vibrating mechanism as well as being moved in accordance with the field-shift. Needles, vibrating Laterally.-The mechanism; as described in the parent Specification, comprises a pitman 64' reciprocated by a needle-vibrating eccentric 62 on a transverse shaft, an arm 69 connected to an arm 71 engaging a field-shifting cam 40, and a combining lever 66 connected to the needle-bar gate 29 by a link 68. In the mechanism described in the present Specification the eccentric 62 is a variable throw eccentric of known kind adjusted by longitudinal movement of a rod sliding in a bore in the eccentric shaft and spring- pressed towards the position of minimum throw; the end of this rod is engaged by the vertical arm of a lever 116, of which a horizontal arm extends beneath the machine arm and carries an adjustable abutment screw 118 for engagement with an arm 120 rigid with the arm 69 or, in a modification, with a similar arm actuated by a separate cam on the same shaft as 40. The lever 116 may also carry an adjustable stop screw which engages the under side of the machine arm to determine the minimum amplitude of vibration, or maintain the amplitude at its maximum, independently of the form of the control cam. The cam-actuated arm 71 may be slid on its spindle to withdraw it from the cam and to lock it and the arm 69 in a fixed position, the machine then producing a zig-zag seam in a straight line and, in the form shown, of fixed amplitude; in the form where the eccentric throw is controlled by a separate cam similar disconnecting means may be provided for independently fixing the amplitude of needle-vibration. Cords, applying.-The arm 91 carrying the finger 36 for laying a surface cord under the zig-zag stitching, instead of being pivoted to the presser-bar and rocked by a link 78 from the arm 69 which controls the field of vibration of the needle, is pivoted to a bar 84 slidable in a yoke 81 on the presser-bar. The bar 84 is shifted by the link 78, and the upper end of the arm 91 has a slot engaging a pin on the needle-bar gate 29, so that the cord is shifted laterally in accordance with the needle vibration but in the opposite direction; the cord is thus kept well clear of the needle at each stroke. The cord is led to the finger 36 through a tension device 34 and a wire eye carried by the lower end of the machine head.