Patent GB-935859-A (GB)
Title: Assembly for controlling the rotary hook and the material-transporting claw in sewing machines
IPC: D05B27/22
Filed: 1961-05-25
Abstract: 935,859. Sewing machines. FRATELLI BORLETTI S.p.A. May 25, 1961 [May 25, 1960], No. 18988/61. Class 112. [Also in Group XXIV] A sewing machine comprises a rotary hook, a feed dog, and common driving means therefor mounted on a frame detachably secured to the main frame of the sewing machine, said driving means being adapted to impart to the feed dog two movements in a horizontal plane and substantially at right angles to one another, said movements being separately adjustable in both magnitude and sense. A horizontal shaft 3, Figs. 1 to 9, journalled in a frame 9, is driven by a belt I on a pulley 2 adjustably mounted on a conical rubber bushing 4 clamped with a wedging action by a screwthreaded ring 5. Shaft 3 is directly coupled to a rotary hook 6. A gear 10 on shaft 3 meshes with a gear 11 on a vertical shaft 13. A cam 12 on gear 11 is adapted to impart feed lift movements to a feed dog 15, and an eccentric or three-lobed cam 14 on shaft 13 is adapted to impart the two component feed-advance movements to the feed dog. A fork 18 embracing cam 14 is pivoted on a vertical pin 19 and is releasably coupled to an arm 20, also pivoted on pin 19, by the engagement of a ball 21, carried by fork 18, with a recess in a curved spring 21<SP>1</SP> rigid with arm 20. Shaft 3 passes with clearance through an aperture 20<SP>1</SP> in arm 20 to permit the latter to oscillate with fork 18. Arm 20 carries two vertical pins 22, 23 on which are pivoted the first members of kinematic chains adapted to control the respective component feed advance movements of the dog 15. A pair of links 24, 26, pivoted together at 25, are respectively pivoted at 22 to arm 20 and at 27 to an arm 28 pivoted on a fixed vertical pin 29. A fork 33, pivoted on pin 29 and secured by a stud 34 to arm 28, carries opposed vertical pins 35 on which is pivoted a member 36. An extension 16<SP>1</SP> of member 36 carries a horizontal pin 16 on which is pivoted an end of a feed bar 17, the other end of which carries the dog 15. A pivotal link 30 connects link 26 to one end of a bellcrank lever 31 pivoted to the frame 9. A pair of links 38, 40, pivoted together at 39, are respectively pivoted at 23 to arm 20 and at 41 to an arm 42 pivoted on pin 29. A link 43 connects link 40 to one arm of a bell-crank lever 44 pivoted to the frame 9. Arm 42 is connected at a point adjacent pin 41 by a flexible link 45 to extension 16<SP>1</SP>. As shown in Fig. 9a, arm 20 oscillates between the full and broken line positions, and pin 25 lies on a line bisecting the angle between these positions. Pin 27 therefore remains stationary and no feed-advance movement is imparted to dog 15. If pin 25 is moved to either side of its mid position, by manual operation of bell-crank lever 31, pin 27 transmits oscillatory movement to arm 28, and arm 33 thereby vibrates dog 15 along the axis X-X. Similarly, oscillation of arm 42 causes vibration of dog 15 along the axis Y-Y, via flexible link 45. Feed lift cam 12 co-operates with a lobe 46 on a bar 47 having a lobe 50 supporting the feed bar 17. Bar 47 co-operates with the free ends of two levers 48, 49, pivoted to frame 9, in such a manner that it moves rectilinearly in a vertical plane. Lever 48 may be manually operated to shift from a normally-engaged surface 51 on bar 47 to a surface 52, when bar 47 is moved downwardly to position dog 15 permanently below the level of the throat plate 53. In a modification, Figs. 10, 12, a horizontal shaft 103, journalled in a frame 109, is coupled by gearing 160, 161 to a horizontal shaft 103<SP>1</SP> which is disposed at right angles to shaft 103 and carries a rotary hook 106. Further gearing, not shown, couples shaft 103 to a vertical shaft which carries an eccentric adapted to oscillate a double-armed lever 120 about a fixed vertical pivot 119. A pin 122 on one arm of lever 120 is pivoted to a link 124 which in turn is pivoted to a link 126, the latter being pivoted at 127 to one arm of a bell-crank lever 128 pivoted on a fixed vertical pin 129, the other arm of lever 128 being pivoted to a horizontal bar 164. Bar 164 is pivoted at 165 to the upper end of a vertical bar 167, the lower end of which is pivoted to the frame 109. Bar 164 is also connected by flexible horizontal bars 162, 163 to a horizontal member 116<SP>1</SP> which is supported by vertical rods 166 having bell and socket connections with the frame 109. Member 116<SP>1</SP> is connected by a flexible member 116 to feed-bar 117 carrying the feed dog 115. Oscillation of lever 120 may therefore be converted, via links 124, 126, into movement of dog 115 along the axis X-X. A pin 123 on the other arm of lever 120 is pivoted to one end of a link 138 pivoted at its other end to one end of a link 140. A pin 141 on the other end of link 140 is connected by a bar 145 to member 116. Pivotal movement of lever 120 may therefore be converted into movement of dog 115 along the axis Y-Y.