Patent GB-1197489-A (GB)
Title: Material Stitching and Guiding Apparatus
Inventor: WINBERG RAGNAR W
IPC: D05B23/00
Filed: 1967-12-16
Abstract: 1,197,489. Sewing machines. R. W. WINBERG. 16 Dec., 1967, No. 57261/67. Heading D1G. [Also in Division G3] Apparatus adapted to sew along a predetermined line comprises means for advancing a workpiece along a normal feed path, a guide rail mounted for movement relative to the normal feed path, a clamp adjustably mounted on the guide rail and engagable with the trailing end of the workpiece adjacent an edge thereof when the leading end of said edge is initially positioned operatively in relation to the stitching point, and control means responsive to the deviation of said edge from the normal feed path for moving the guide rail to restore said edge to the normal feed path. The main shaft 20 of a sewing machine 16, mounted on a work-supporting table top 14 is driven by a belt 34 from a motor 30 via a clutch 38 actuated by a bell crank lever 40 on energisation of an air jack C5. The presser foot 28 is raised on energisation of an air jack Cl. A puller feed wheel 46 is connected by a flexible driving shaft 47 to a shaft 48 driven via a belt 56 and adjustable diameter pulley 58 from shaft 20. Shaft 48 is also coupled by gearing 78, 80, 82 to a driving shaft 72 for endless belts 62, 64, 66. the upper runs of which are supported by the table top 14, and which support and advance a workpiece M having a contoured edge e parallel to which a seam 86 is to be sewn. A guide rail 88 is supported at one end on table top 14 by a roller 176, and at the other end is rigid with a bar 94 adjustably pivoted about a fixed vertical post 92. A trolley 110, movably supported on rail 88 by rollers 112a, is biased to a starting position remote from the stitching point at the needle bar 22 by a counterweight (128) connected to trolley 110 by a cable 130 guided by pulleys 132, 134, 136. Trolley 110 carries a pair of vertically-spaced plates 116, 118 which, in the starting position of trolley 110, are disposed respectively below and above the trailing end of edge e. A bell-crank lever, pivoted on trolley 110, has a horizontal arm 122a carrying a pin 120 adapted to pass through a hole in plate 188 for penetrating the workpiece M, and a vertical arm 122b connected to the armature of a solenoid 51 mounted on trolley 110 and normally energised to raise pin 120, against spring bias, above plate 118. Trolley 110 in its starting positions abuts the retracted plunger 138 of an air jack C4 adjustably secured to rail 88. At the end of rail 88 adjacent the stitching point are mounted an air jack C3 having a normally-extended plunger 144, and a normally-closed limit switch 55. Rail 88 is connected by a link 172 to one arm 168 of a bell crank lever, the other arm 162 of which is pivoted to the plunger of a double-acting air jack C6, the cylinder of which is pivoted to a fixed post 158. A sprocket 188, turnable with bell crank lever 162, 168, is connected by a chain 186 to a sprocket 184 which is journalled on a fixed post 182 and carries a conductive finger TPa. A disc TP, journalled on post 182, carries conductive segments TPa', TPa", and may be turned by a handle 178 to position finger TPa either between the segments or in contact with either one of the latter. Finger TPa is connected via a normally-closed contact R4a' of a relay R4 to the terminals X, Y of respective relays A1, A2. Segments TPa', TPa" are respectively connected to the terminals X', Y' of relays A1, A2. Relay A1 has a normallyclosed contact A1a in series with a solenoid valve V4 supplying compressed air to the left hand end of jack C6. Relay A2 has a normally-closed contact A2a in series with a normally-closed contact R4b' of relay R4 and with a solenoid valve V5 supplying compressed air to the right hand end of jack C6. The arrangement is thereby such that finger TPa is normally positioned between the segments TPa', TPa", and that if dial TP is turned to engage finger TPa with either one of said segments, the relay A1 or A2 connected to the engaged segment will be energised to open the associated contact, and jack C6 will operate until finger TPa is again positioned between the segments corresponding to a readjusted position of rail 88. Photocells P1, P2, positioned in advance of the stitching point. are connected to respective terminals X', Y' and to a normally-open contact R4a" of relay R4. A normally-open contact A2b of relay A2 is connected in series with switch V5 and with a normally-open contact R4b" of relay R4. A pair of vacuum ducts 154 are provided in table top 14 between the stitching point and the photocells P1, P2, and a pair of downwardly-directed compressed air ducts (190) are aligned with the ducts 154 for holding the workpiece against table top 14. To start a sewing operation, the leading end of edge e is positioned under the raised presser foot 28, edge e is arranged to pass between the photocells P1, P2, and dial TP is turned to position rail 88 such that pin 120, when lowered, may penetrate the trailing end of edge e. A foot-switch FS1 is then momentarily closed, Whereby a relay R2 is energised to close a holding contact R2b, to close a contact R2a" in series with a normally-open foot-switch FS2, and to open a contact R2a' in series with a relay R1 The latter is thus deenergised to open a contact R1a in series with a solenoid valve V1 supplying air to jack C1 to lower presser foot 28, and also to a jack C2 for shifting a thread chain cutter 148 out of the line of stitching. Foot-switch FS2 is then momentarily closed to energise relays R3 and R4, whereby a holding contact R3b for said relays is closed, a contact R3a' is opened to de-energise solenoid SL for engaging pin 120 with the workpiece M and for de-energising a solenoid valve V2 for retracting the plunger 144 of jack C3, while a contact R3a" is closed to energise a solenoid valve V3 for supplying air to jack C5 for engaging clutch 38 to operate the sewing machine and the means for advancing the workpiece along a normal feed path, and also for supplying air to jack C4, whereby plunger 138 is advanced to initiate movement of trolley 110 along rail 88. Contacts R4a, R4b' are also opened, and contacts R4a", R4b" are closed, whereby relays A1 A2 are put under control of the photocells P1, P2. Photocell P1 is normally covered by the workpiece, whereby relay A1 is deenergised and contact A1a is closed for supplying air to the left hand end of jack C6. Photocell P2 is normally uncovered, whereby relay A2 is energised to close contact A2b for supplying air to the right hand end of jack C6. The position of rail 88 thereby remains unchanged until either photocell P1 is uncovered or photocell P2 is covered, when jack C6 operates to move rail 88 until edge e is repositioned between the photocells P1, P2 to sew seam 86 parallel to edge e. When the limit switch SS is opened by the advancing trolley 110, relays R1, R2, R3, R4 are deenergised, whereby photocell control is removed, pin 120 is raised, clutch 38 is disengaged, plunger 138 is retracted and plunger 144 is advanced to initiate movement of trolley 110 in the return direction. A delay is, however, incorporated in relay R1, whereby contact R1a remains closed until the inertia of the sewing machine advances the trailing end of the workpiece beyond the stitching point. On opening of contact R1a, presser foot 28 is raised and cutter 148 is swung across the line of stitching to sever the thread chain behind the workpiece.