Patent GB-1108141-A (GB)
Title: Improvements in or relating to work traversing mechanisms in sewing machines
Inventor: LAWS ARTHUR ERNEST
IPC: D05B39/00
Filed: 1963-09-20
Abstract: 1,108,141. Sewing machines. TRUBENISED CO (GT. BRITAIN) Ltd. 18 Sept., 1964 [20 Sept., 1963; 25 Oct., 1963; 8 Jan., 1964], Nos. 37062/63; 42177/63 and 845/64. Heading DIG. A sewing machine comprises a work-holder movable in two mutually transverse directions in a plane, two fluid-pressure servo-motors, controlled by respective valve means, for moving the work-holder in said directions, a template holder, a template follower movable in two mutually transverse directions in a plane, means for maintaining contact between said follower and a template mounted .on the template holder and for effecting relative movement therebetween, and a mechanical linkage adapted to transmit said relative movement to said valve means, whereby the servo-motors effect corresponding movement of the workholder relative to the sewing machine needle. Longitudinal frame members 11 a, 11 b Fig. I, are interconnected by lateral bars 12a, 12b. 12c, 12d. Bars 17, 18, interconnecting members 11a, 11b, carry a soft iron template 19 comprising hand-shaped portions 21, 22. A member 34, movable on bar 12a, is connected by bars 36, 37 to a member 38 movable on bar 12b. A plate 48, movable on bars 36, 37, supports an electric motor driving a magnetised roller 57 adapted to follow the contours of template 19. A member 68, movable onbar 12c, is connected by bars 66, 67 to a member 65 movable on bar 12d. A workholding plate 70, disposed under the needle bar 178, is movable on bars 66, 67. A pneumatic cylinder 77, parallel to bars 12, is fixed to member 68 and houses a piston 78 on a piston rod 79 connected by a flexible member 83 to member 11b. A valve cylinder 84 rigid with cylinder 77, is connected to the opposite ends of the latter 'by passages 85, 86 normally closed by a slide valve 88 connected by a flexible member 94 to member 38. Movement of the latter in one direction along bar 12b thereby admits compressed air to one end of cylinder 77 to effect equal movement of member 68, and work-holder 70, in the same direction. A pneumatic cylinder 94, perpendicular to bars 12, is fixed to work-holder 70, and houses a piston 96 on a piston rod 97 connected by a flexible member 99 to member 68. A valve cylinder 102, fixed to holder 70, is connected by passages 107, 108 to the opposite ends of cylinder 94 and houses a slide valve 104 which normally closes said passages and is connected by a rod 111 and flexible members 112, 113 to plate 48. Movement of the latter in one direction along the bars 36, 37 thereby results in equal movement of holder 70 in the same direction. A clamp associated with the work holder is operated by the reciprocating movements of the needle bar 178 for holding the work stationary while each stitch is formed. In a modification, Fig. 6, work-holder 70 is movable longitudinally as in Fig. 1, on bars 66, 67 by pneumatic motor 94, and transversely on bars 12c, 12d by pneumatic motor 77. Bars 180, rigid with holder 70, are connected by a rod 182 and flexible members 181, 185 to bars 183 rigid with a plate 189. A rod 187 is connected at respective ends, by Hooke's joints 188, with a third bar rigid with holder 70 and a bar 186 rigid with plate 189. An electric motor 54, carried by the latter, drives a magnetised roller 57 engaged with a fixed template 19. A valve 191, as described in Specification 973861, has an upper disc 192 separated by a central hollow spacer from a lower disc 193. A collar 195, positioned slidably between discs 192, 193, normally covers four equal-spaced concentric apertures in disc 192 connected to the respective cnds of the cylinders 77 and 94. The space enclosed by the discs 192, 193 and collar 195 is pressurised via the spacer. Collar 195 is connected to plate 189 by a member 202 adapted to flex vertically but rigid horizontally. The arrangement is such the movements of plate 189 relative to holder 70, by virtue of the flexble connections, are transmitted to collar 195 for operating the motors 77 and 94. In a further modification. Figs. 3, 4. frame members 120, mounted on supports 121, are interconnected by rods 122a, 122b. Rod 122a carries a piston 125 disposed in a pneumatic cylinder 126 connected by rods 128a, 128b to a bar 129 carrying a roller 131 movable on I rod 122b. Rod 128a carries a piston 132 disposed in a cylinder 133 rigid with a workholder 135 which carries a roller 137 movable on rod 128b. Four pins 138, depending from bolder 135, support a template 139 comprising two hand-shaped portions 141, 142. A rod 145, mounted in a gymbal bearing 146 supported on members 147 interconnecting frame members 121, carries at its upper end an electric motor 143 driving a magnetised roller 144 co-operating with template 139. The lower end of rod 145 carries a spherical valve member 148 disposed in a chamber 169 in a valve body 149 immersed in an oil-filled casing 152, aligned passages 161, 162 lead radially outwardly from chamber 169, and similar passages 163, 164 (not shown) are disposed at right angles thereto. The outer ends of said passages are connected to the cylinders 126, 133, and the mid points of said passages are connected by respective passages 158, each containing a constriction 159, to a passage 157 receiving oil under pressure from a pump connected to an outlet 156 in casing 152. The arrangement is thereby such that pressure rises in that one of the passages 161 to 164 closed at the inner end by member 148, and the latter and chamber 169 are so arranged that the cylinders 126 and 133 are appropriately operated. In order to allow the work-holder to follow a path including a sharp external corner, the template having an external corner corresponding thereto is provided with an auxiliary template which has a re-entrant corner positioned about the external corner at a distance therefrom slightly greater that the diameter of the follower roller, and the latter, when approaching the external corner, is diverted to engage the auxiliary template, its direction of rotation being reversed while it is in contact with the latter.