AUTOMATIC SEAMING MACHINE

Abstract: An automatic seaming machine for joining by weaving two opposed fabric ends. The machine comprising an end selector (50) driven by an end selector drive for selecting a free warp yarn and an inserter means (70) driven by an inserter means drive for pulling the yarn thus selected through the shed to join the ends together. A fault detector monitors the selection of the yarn by the end selector (50), and an inserter pick-up detector monitors the engagement and pulling of the yarn by the inserter means (70), such that if a fault occurs in either the selection or engagement/pulling the respective fault detector and inserter pick-up detector sends a fault signal to a central control means which in turn then sends a stop signal to the end selector drive and the inserter means drive in order to bring the machine to a complete halt and thereby terminate the weaving process.

Description: Automatic Seaming Machine The present invention relates to automatic seaming machines, and in particular, but not exclusively to automatic seaming machines for use in joining together the ends of papermakers fabrics to produce an endless structure. A seaming machine for joining together the ends of a papermakers fabric in order to form an endless belt is known from WO84/00782 (Scapa) . In this prior machine, as illustrated in Figs. 16 to 18, in order to join two opposed fabric ends 1 1 , 1 2 by successively weaving the individual ones of two sets 1 3, 1 of side by side free warp yarns extending from the fabric edges 15, 16 with a seaming weft 17 formed from pre-crimped yarns, shed fingers 31 , 32 are moved by a pneumatic piston and cylinder arrangement 33 to open up a shed 20. Two further pneumatic arrangements 40, 42 control a selector means 25 having an actuable pin 39 which selects a free warp yarn 28 from one end 1 2 of the belt and moves it into engagement with notch 44 of a dependent guide bar 43. A further pneumatic arrangement 45 drives inserter needle 26 through the shed 20 to pick up the yarn 28 with its crook-end 27. The inserter needle 26 is then driven back through the shed 20 drawing the yarn 28 with and engages yarn 28 with yarn clamps 29, whereat that part of the yarn which extends beyond the region of weaving is severed by a yarn cutter. The yarn 28 is then tensioned and is beat-up by reed 30. The shed is then changed and a new shed opened and a yarn drawn from the other end 1 3 of the belt by a second selector and inserter means 25, 26 (not illustrated) each having respective pneumatic drive means. The process is then successively repeated until the ends of the fabric are completely joined. In this process the free warp yarns 1 3, 1 4 are supported by respective leases 22 (36,37) and the weft 17 is supported by a shedding mechanism 1 8 operating in accordance with a predetermined pattern. The above described system of joining the two ends of the fabric has the drawback that the operator must watch the drawing of each warp through the shed. This is because the selector means may accidentally select more than one warp, or may fail to pick up a warp with the consequence that the inserter needle draws too many warps or no warp through the shed. Also when the warp is drawn through the shed and engaged with the clamp and severed, the yarn may not be fully released from the inserter needle and may be drawn, or a portion of the yarn (debris) may be retained and become entangled in or interfere with the joining process. Once this error has been spotted it is necessary for the operator to switch-off the seaming machine. Unfortunately, due to human error, there may be a delay in switching the machine off, but more significantly because each part of the process is controlled by an individual pneumatic drive the machine cannot be brought to an immediate halt and therefore several further warps may have been successively drawn through the shed from each end of the fabric before the machine comes to a complete halt. This has the consequence that the operator must then carefully un-pick by hand several complete warp insertions before it is possible to access and thereby unpick the portion where more than one warp, or no warp or debris has been drawn through the wefts. This is a time consuming process and results in considerable down-time for the machine. The end/yarn selection mechanism of this known seaming machine is operated by a jacquard patterning arrangement to divide the yarns by independent movement of the yarns to create a desired woven design for the joining process. The pattern is selected by a cam mechanism comprising a plurality of individual cams. This has the drawback that only simple patterns can be utilised in the seaming machine because the complexity of the repeat pattern is limited by the number of faces it is possible to place on each individual cam. Furthermore it is not possible to place an odd number of faces on one cam. It is an object of the present invention to overcome or alleviate the above described drawbacks. In accordance with a first aspect of the present invention there is provided an automatic seaming machine for the mechanical joining of opposed fabric ends, having a fault detector which monitors the seaming process and an automatic stop for bring the seaming process to a halt if an error is detected by the fault detector. This has the advantage that the joining process is continuously monitored by the fault detector and if an error occurs the seaming machine is brought to a halt more quickly. Preferably the drive for the seaming process comprises a mechanical cam. This has the advantage that when the process is stopped the seaming operation stops faster than it would with the previously known pneumatic drive for the seaming process. Preferably the fault detection means comprises an electrical circuit having a switch the actuation of which sends a signal to the stop mechanism that a fault has occurred. In a preferred embodiment the seaming machine comprises a yarn engagement means selectively engageable in use with successive side-by- side free yarns, wherein the fault detector is adapted to monitor the selection of a yarn by the yarn engagement means and to detect a fault if more that the required number of yarns is selected. This has the advantage that if more than the required number of yarns are selected the seaming operation is stopped before it progress to the next stage, whereat the yarns would be drawn through the shed. Preferably the yarn selector comprises at least one pin for selecting a yarn which is pivotally mounted to the main body of the selector, wherein the fault detector comprises an electrical circuit having two contacts with one of the contacts attached to the pivotally mounted pin and the other to the main body of the selector. By this means if more than the required number of yarns is selected then the connection of the contacts is broken because of the restrictive force experienced by the pin pivoting the contacts apart. Preferably means are provided to adjust the connection of the two contacts. Thereby the force required to open the contacts can be adjusted to suit a required pull for the yarns. In a preferred embodiment the seaming machine comprises yarn insertion means engageable with a free yarn selected by the yarn engagement means and adapted, upon actuation, to pull the yarn through the shed, wherein the fault detector is adapted to monitor the collection of yarn by the yarn engagement means and to detect a fault if no yarn is present. This has the advantage that the machine can be switched off when no yarn is drawn through the shed and before the shed is changed. Preferably, the fault detector is also adapted to monitor the return of the yarn insertion means through the shed once it has deposited its yarn end at the other side of the shed, the fault detector detecting a fault if a portion of yarn remains engaged with the yarn insertion means. This has the advantage that the machine is stopped if a severed portion of the yarn, or debris is still attached to the insertion means. Preferably the yarn insertion means comprises a clamp wherein in a first position of the clamp whereat no yarn is held by the clamp on the insertion means an electrical contact is made to the fault detector and in a second position of the clamp whereat a yarn held by the clamp on the insertion means said electrical contact is broken. This has the advantage that the fault detection can be monitored by the simple breaking or making of a circuit. Preferably the fault detector is adapted to monitor the progress of the yarn insertion means and such that no fault is detected when electrical contact is broken when a yarn is correctly engaged by the clamp of the insertion means and such that a fault is detected during the later progress of the yarn insertion means if once the yarn has been deposited at the other side of the shed a portion of the yarn is still present causing the breaking of the electrical contact. In a further preferred embodiment the fault detector comprises a camera which monitors the seaming process, the data collected from the camera being analysed by a computer and a fault detected if the seam process does not conform to a pre-programmed pattern. In accordance with a second aspect of the present invention there is provided a yarn selector for determining which free yarn is to be selected, the yarn selector comprising electronic means for determining the position of at least one yarn engagement pin of the yarn engagement means. This has the advantage that the yarn can be selected with an increased number of possibilities, when compared to the known mechanical method of selection. Preferably the electronic means comprises a plurality of solenoid operable according to a predetermined pattern or sequence to selectively stop the movement of said pin. In accordance with a third aspect of the present invention a method for the mechanical seaming of opposed adjacent fabric ends is provided which includes the steps of monitoring the seaming process in order to detect errors in the joining of the fabric ends, detecting an error if one occurs, sending a message to a central control unit that an error has occurred, and sending a stop signal to the drives of all moving components involved in the seaming process in order to switch off the drives and bring to a halt the seaming process. By way of example only, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a stop mechanism for a seaming machine constructed in accordance with a first embodiment of the present invention; Fig. 2 is a schematic view of the end selection assembly of Fig . 1 taken in the direction of arrow A; Fig. 3 is a view similar to Fig. 2 illustrating the breaking of contact when incorrect selection of yarn occurs; Fig. 4 is a schematic view of a stop mechanism constructed in accordance with a second embodiment of the present invention; Fig. 5 to 7 are schematic sectional views along A, B and C respectively of Fig. 4; Fig. 8 is a view similar to Fig. 7 bit shows the clamping of a free yarn; Fig. 9 is a block diagram illustrating the connection of the stop mechanisms; Fig. 10 is a schematic view of an end selection assembling constructed in accordance with the present invention; Figs. 1 1 are views in the direction of arrows A, B and C of Fig. 10, to 13 each also showing an end view of the solenoids; Fig. 14 is a view in the direction of arrow D of Fig. 10; Fig. 1 5 is an exploded view of the solenoids and retaining block of Fig. 10; Fig. 1 6 is a perspective view of a part of a known seaming machine illustrating the weft yarns displaced to provide a shed at one edge thereof, with the shed finger means engaged therewith at an initial position; Fig. 17 is a view corresponding to Fig . 16 illustrating a later stage in the seaming operation whereat a free warp yarn has been selected and drawn to a position for engagement by a yarn inserter; and Fig. 18 is a side elevation showing the selector with a free warp yarn engaged therein. The automatic seaming machines comprises a stop mechanism which is adapted to bring the machine to a complete halt when an error occurs in the weaving (joining) of two fabric ends. In a first embodiment the selector means 25 of the seaming machine of WO94/00782 is modified in that the selector means 50 comprises, as illustrated in Figs. 1 to 3, a selector block 52 having a free warp yarn engaging pin 54 mounted therein for operation under the control of a cam mechanism to engage and clamp the end yarn 28, of the free warp yarns, supported by the lease 22, to the block 52. The block carries 3 end selectors/pins 54 which can be selected to enter slots 1 1 6 on guide plate 1 1 8 for a preprogrammed yarn selection as described hereinafter. The block 52 is slidably mounted on slide 56 such that upon selection of a yarn the yarn is separated from the free warp yarns by the pin 54 dragging the selected yarn from the lease 22 as block 52 moves up the slide 56. The pin or end selector 54 rests against a fulcrum arm 58 which is pivotally mounted to the selector block 52 about pivot 60. Two contacts 62, 64 make a circuit via connection 66 with contact 62 being attached to fulcrum arm 58 and contact 64 being connected to the selector block 52. If, however, during the selection process, more than one free warp yarn has been selected the restrictive force incurred on the pins 54 ability to drag a yarn from the lease, as the end selector 52 swings away, causes the pin 54 to push against the fulcrum arm 58 and results in the contact 66 between terminals 62, 64 opening and the circuit being broken causing the machine to stop. If a yarn is correctly selected, the yarn being clamped between the end selector 54 and block 52 is moved into engagement with the guide bar for subsequent collection by the inserter means. In order to ensure that the connection 66 is closed during normal operation, and therefore that two separate portions 66a, 66b of the connection 66 touch each other to create a connection between contacts 62, 64, the fulcrum arm 58, to which contact 64 is attached, is held under tension by a spring 68. The spring tension determines how much force is required to push the fulcrum arm 58 forwards by the end selector 54 currently selecting a free warp yarn. The spring 68 is held between a first spring anchor 70 connected to the fulcrum arm 58 and a second spring anchor 72 connected to the selector block 52. The tension of the spring 68 is adjusted by rotating a knurled adjuster 74. In a second embodiment of stop mechanism which stops the seaming machine if an error occurs during the transfer of a yarn, is best illustrated in Figs. 4 to 8. The inserter means which is reciprocally mounted for movement through the shed to collect from the guide bar and pull through the shed the selected free warp yarn 28, is modified in that inserter arm 70 carries a clamp 72 for engaging the yarn 28. The clamp 72 is attached to the arm 70 by screw 74. For this purpose one end of the clamp 72 is in the form of a preformed loop 76. The screw 74 passes through washer 78, the preformed loop 76 and a plastics annular spacer 80 having an annular protuberance 82 which extends through the interior of the preformed loop 76. Sandwiched between the spacer 80 and loop 76 is an electrical cable 84 which also has a loop 86 at its end formed from bare wire. The protuberance 82 of spacer 80 also fits through the cable loop 86. When screw 74 is tightened the bare wire loop 86 of cable 84 makes contact with th Θ preformed loop 76 end of the clamp 72. The spacer 80 and its protuberance 82 and washer 78 are of plastics and insulate the clamp 72 and the bare wire end 86 of the cable 74 from the screw 74 and the inserter arm 70 to ensure a clean circuit and no shorting out. The inserter arm 70 and screw 74 form the ground side of an electrical circuit, whilst the clamp 72 forms the positive input as long as it is touching the face of the inserter arm 70. Under normal running conditions if a yarn end is collected it is held between clamp 72 and one face 88 of the inserter arm 70. The diameter of the yarn is enough to push the clamp 72 away from the face of the inserter and break the circuit and hence allow the machine to continue running. However if no end is collected then the clamp 72 remains touching the inserter arm's face 88 and the circuit is not broken and the machine is adapted to stop. As well as insulating the area where the clamp 72 is attached to the inserter arm 70, the area where the clamp 72 passes through eye 90 of the inserter arm 70 is also insulated to prevent shorting-out. This is achieved by ensuring that clamp 72 is the correct length after bending to pass through the eye 90 and is held in place by two plastics guides 92 used to position the clamp centrally within the eye 90. In a third embodiment of stop mechanism as best illustrated in Figs. 4 to 8, a stop mechanism which stops the seaming machine when debris is detected shares the same circuit as the transfer stop mechanism. However, whereas the transfer stop mechanism stops if there is no yarn present, the debris stop motion stops if there is an end or debris present. In this instance the clamp 72 is in permanent contact with face 88 of the arm 70 creating a circuit. As the inserter arm 70 starts to move towards the shed at the start of its cycle, if there is any debris present the clamp will be displaced away from the face 88 of the inserter 70 and the circuit will be broken and the machine will stop. The stop mechanisms of the first, second and third embodiment are all connected into a central control unit (Fig. 9) which monitors the status of each stop mechanism. If any of the mechanisms detects a fault a message is sent to the central control and the power is then cut to all machine component drives to stop their operation and bring the machine to a halt. Unlike the seaming machine of WO84/00782, the moving components of the present machine are largely mechanically driven by a cam mechanism, rather than by pneumatic pistons and cylinders, therefore the machine can be stopped more quickly. In addition to the aforementioned stop assemblies a camera is used to monitor the joining of the fabrics, which camera is adapted to optically recognise any anomoly in the seaming process. If such an anomaly is detected a stop signal is sent to the central control unit and the power cut as mentioned hereinbefore. The central control unit also sends a signal to a visual display which is adapted to inform the operator at which location in the machine the error has occurred. ln a fourth embodiment, as best illustrated in Figs. 10 to 1 5, the end or yarn selection is modified in that the selection assembly 100 comprises a solenoid retaining block 102 in which are located 3 solenoids 104, 106, 108. Each solenoid carries a stop 1 10, 1 1 2, 1 14 (as best illustrated in Fig . 1 5). When de-energized the stops 1 10, 1 1 2, 1 14 are so positioned so that they locate directly underneath their respective slot 1 16 in guide plate 1 18. When energized the stops 1 10, 1 1 2, 1 1 4 are pulled away and leave their respective slot clear. During end/yarn selection the solenoids are energized and de- energized to a pre-programmed pattern or sequence, allowing their respective stops to either remain and block the slot 1 16 in the guide 1 19 or be pulled away to clear their slots. This allows the pin or end selectors 54 to either enter a slot or be held outside a slot depending on the program or sequence selected with the pin/end selector 54 selecting entering the slot.

Claims: Claims 1 . An automatic seaming machine for the mechanical joining of opposed fabric ends, having a fault detection means which monitors the seaming process and an automatic stop for bringing the seaming process to a halt if an error is detected by the fault detector. 2. An automatic seaming machine according to claim 1 , comprising a drive for the seaming process which drive comprises a mechanical cam. 3. An automatic seaming machine according to claim 1 or 2, wherein the fault detection means comprises an electrical circuit having a switch the actuation of which sends a signal to the stop mechanism that a fault has occurred. 4. An automatic seaming machine according to any one of the preceding claims comprising a yarn selector selectively engageable in use with successive side-by-side free yarns, wherein the fault detector is adapted to monitor the selection of a yarn by the yarn engagement means and to detect a fault if more that the required number of yarns is selected. 5. An automatic seaming machine according to claim 4, wherein the yarn selector comprises electronic means for determining the position of at least one yarn engagement pin of the yarn engagement means. 6. An automatic seaming machine according to claim 5, wherein the electronic means comprises a plurality of solenoid operable according to a predetermined pattern or sequence to selectively stop the movement of said pin. 7. An automatic seaming machine according to claim 4, wherein the yarn engagement means comprises a main body and at least one pin for selecting a yarn, which pin is pivotally mounted to said main body, and the fault detection means comprises an electrical circuit having two contacts with one of the contacts attached to the pivotally mounted pin and the other to the main body of the selector. 8. An automatic seaming machine according to claim 7, wherein means are provided to adjust the connection of the two contacts. 9. An automatic seaming machine according to any one of claims 4 to 8, comprising yarn insertion means engageable with a free yarn selected by the yarn selector and adapted, upon actuation, to pull the yarn through the shed, wherein the fault detection means is adapted to monitor the collection of yarn by the yarn engagement means and to detect a fault if no yarn is present. 10. An automatic seaming machine according to claim 9, wherein the fault detection means is also adapted to monitor the return of the yarn insertion means through the shed once it has deposited its yarn end at the other side of the shed, the fault detection means detecting a fault if a portion of yarn remains engaged with the yarn insertion means. 1 1 . An automatic seaming machine according to claim 9 or 10, wherein the yarn insertion means comprises a clamp wherein in a first position of the clamp whereat no yarn is held by the clamp on the insertion means an electrical contact is made to the fault detection means and in a second position of the clamp whereat a yarn is held by the clamp on the insertion means said electrical contact is broken. 1 2. An automatic seaming machine according to any one of claims 9 to 1 1 , wherein the fault detection means is adapted to monitor the progress of the yarn insertion means and such that no fault is detected when electrical contact is broken when a yarn is correctly engaged by the clamp of the insertion means and such that a fault is detected during the later progress of the yarn insertion means if once the yarn has been deposited at the other side of the shed a portion of the yarn is still present causing the breaking of the electrical contact. 13. An automatic seaming machine according to any one of the preceding claims wherein the fault detection means comprises a camera which monitors the seaming process, the data collected from the camera being analysed by a computer and a fault detected if the seaming process does not conform to a pre-programmed pattern. 14. An automatic seaming machine for the mechanical joining of opposed fabric ends, having a yarn selector for determining which free yarn is to be selected, the yarn selector comprising electronic means for determining the position of at least one yarn engagement pin of the yarn engagement means. 1 5. An automatic seaming machine according to claim 1 2, wherein the electronic means comprises a plurality of solenoid operable according to a predetermined pattern or sequence to selectively stop the movement of said pin. 16. A method for the mechanical seaming of opposed adjacent fabric ends including the steps of monitoring the seaming process in order to detect errors in the joining of the fabric ends, detecting an error if one occurs, sending a message to a central control unit that an error has occurred, and sending a stop signal to the drives of all moving components involved in the seaming process in order to switch off the drives and bring to a halt the seaming process.

Inventors: WATERS PAUL, WATERS, PAUL
Applicants: VOITH FABRICS HEIDENHEIM GMBH, WATERS PAUL, VOITH FABRICS HEIDENHEIM GMBH & CO. KG, WATERS, PAUL
Application year: 2000
Main classification: D03D41
IPC codes: D03D41, D03D51, D21F1