EP1000189B1 - Sewing method and sewing machine for releasing a tension thread from a passage formed by a stitch - Google Patents

Abstract

A sewing method having a tension thread, guided and set in a passage of a stitch moved laterally relative to stitching devices between a normal position and a releasing position wherein the tension thread is laterally spaced out of the passage.

Description

The invention relates to a sewing method and a machine for sew for sewing, on a sewing piece such as a soft cover, one stitch sewing formed of threads, called auxiliary threads, of the type forming an extending passage according to the direction of sewing (overlock, zigzag, ...), with a thread, called tension thread, guided and positioned relative to the stitch in the passage simultaneously with stitching of auxiliary wires, so that this tension wire can slide longitudinally and / or laterally in this passage, the tension thread not being stitched by the auxiliary threads forming the stitch.

EP-0 223 312 and US-4 732 097 describe a method and a sewing machine allowing in particular to sew an overlock using threads auxiliaries, and to guide and set up a tension wire in a passage of this overlock, simultaneously and as the overlock is sewn.

This process and this machine are entirely satisfactory. However, efforts have since been made to automate sewing operations. it would indeed allow the entire dressing process to be carried out automatic using a robot.

Now, these particularly delicate sewing operations, still require the presence of a qualified person.

In particular, it is necessary at the beginning and at the end of sewing start and finish the overlock neatly and precisely, and leave strands of protrusion of the tension thread beyond the ends of the overlock by a length sufficient, conventionally greater than 10 cm, to be able to exercise later pulls on these overhang strands, then block by knotting and / or stapling these strands of overshoot after pull-ups. To do this, we must realize a large number of manual operations before sewing, at the start, at the end of sewing, and after sewing (clearing the strands that protrude the tension thread from the overlock and cutting the excess length of overlock).

In addition, at the beginning and at the end of the seam, the overlock must be sewn out of the sewing piece around the tension thread on corresponding lengths to said strands protruding from the tension wire to be left free, and we release and we cut off those unnecessary excess portions of overlock after sewing and release of the part from the machine. Besides that these overlock operations is a waste of thread, time and manpower (which can take significant proportions in the context of large series productions work by this process and this machine), the sewing of the excess portions of overlock without sewing piece corresponds to abnormal machine operation source of malfunction, interruption of production rates, and misalignment or even deterioration of the machine (in particular claws in direct contact with the foot in the absence of material). In particular, it should be noted that the tension thread and overlock assembly cannot be guided, downstream of the stitching means, with the same precision as a sewing piece.

Furthermore, it is also sometimes desirable, in certain applications, to be able to release portions of tension thread out of the overlock in some common parts of the seam, for example to form loops for hanging the sliding tension wire.

The same problems arise with other points of sewing and / or in other applications where a thread is laid, such as a tension thread, simultaneously and as and when sewing a stitch made of threads auxiliaries separate from the tension wire, this tension wire not being an auxiliary seam, and not being stitched, that is to say crossed by the auxiliary threads. For example, the passage for the tension wire can be formed (much less efficient but sufficient in certain applications where the tension wire does not undergo no or undergoes little tension) by a zigzag stitch.

Throughout the text, the expression "tension wire" thus covers any threadlike element (including cord, cord, cord, braid, loop ...), elastic or not, distinct from the auxiliary threads used to form the stitch, which is guided and placed in the passage simultaneously with the stitching of the point of seam without being crossed by the auxiliary threads, so that it can slide longitudinally and / or laterally in this passage.

The invention therefore aims to propose a solution to the problems above, and aims to propose a sewing process allowing forming, at the start of the seam, and / or in the main part of the seam, and / or at the end of sewing, strands of tension thread clear of the passage formed by the stitch -in particular strands beyond beyond the ends of the passage formed by the stitch - in a simple, fast and reliable way.

The invention aims in particular to propose such a method which can be implemented fully automatically, under the control of a programmed control device (robot, automaton, computer system ...) without require human intervention.

The invention thus aims to allow the realization, in particular of fully automatic, strands protruding from a tension wire at the start and at the end of the seam at each end of a passage of a stitch, such as a overlock in which the tension thread is placed simultaneously with the stitching of the stitch, so that it can slide longitudinally and / or laterally.

The invention also aims to allow the realization, in particular of fully automatic, loops of the tension thread released from said passage partly running seam.

The invention aims in particular to propose such a method which authorizes the complete automation of an object wrapping process, such as a seat cover, by a flexible cover, as described by EP-0 223 312 and / or US-4 732 097. The invention aims in this regard to allow productivity gains, savings in labor and raw materials.

The invention also aims to achieve the above goals in a simple and economical way using a simple and inexpensive modification brought to a known sewing machine, in particular an overlock machine as described by EP-0 223 312 and / or US-4 732 097.

The invention therefore also aims to propose a sewing machine allowing the implementation of a method according to the invention.

The invention aims more particularly to propose such a sewing machine obtainable with a simple modification to a known sewing machine, in particular an overlock machine as described by EP-0 223,312 and / or US-4,732,097, after its manufacture.

Throughout the text, the terms "upstream" and "downstream" are used in reference to the direction of sewing by the stitching means of the machine, and to the direction of drive of the part by these stitching means which is therefore driven upstream downstream. The direction of sewing and training of the piece is assumed be horizontal, for the sake of clarity, although this provision, the most common in practice, is not strictly essential in the context of the invention. Likewise, the term "transverse" displacement designates any displacement relative to the direction of sewing and training, having at least one component in a transverse plane perpendicular to the sewing direction and drive by the stitching means. By "lateral" displacement, we mean everything transverse displacement also having at least one horizontal component, i.e. parallel to the workpiece and the work plate, or, in other words, orthogonal to the direction of movement of a needle of the stitching means. Of similarly, the term “vertical” displacement designates any displacement comprising at least one transverse component at least substantially perpendicular to the part to be sewn and to the work-holding plate, i.e. in a plane defined by the sewing direction and by the direction of movement of a needle.

A transverse displacement can therefore be a displacement lateral without vertical displacement, vertical displacement without lateral displacement, or a combination of lateral displacement and vertical displacement.

In addition, the terms "stitching" and "stitched" and their derivatives are used, unless otherwise indicated, broadly to denote the formation of any stitch with threads, without implying that all threads actually cross the thickness of the sewn piece. So the expression "means of stitching "generally designates all means making it possible to achieve a point sewing (within the meaning of standard AFNOR NF G 05-002 whose terminology is adopted in the present application) with one or more sons, and includes in particular one or more needles and / or one or more hooks or loosers.

The invention therefore relates to a method of sewing, on a piece to be sewn and in a sewing direction, a stitch made up of threads, said auxiliary threads, using stitching means of a sewing machine, this point of sewing being of the type forming a passage extending in the direction of sewing, with a thread, called tension thread, guided and placed in this passage simultaneously when stitching the auxiliary wires, so that they can slide longitudinally and / or laterally in this passage, characterized in that it is moved transversely by relative to the stitching means, at least a portion of the tension thread extending to upstream immediately downstream of the stitching means, between a normal position for placing the tension wire in the passage and a release position for said portion of the tension wire where it is inclined relative to the direction of stitching of the stitch, and passes, opposite the stitching means, outside of the area of action of the stitching means and outside said passage, to allow in particular the sectioning independently of the auxiliary wires from the point of sewing and / or tension thread by at least one sectioning knife arranged at downstream of the stitching means and / or the formation of loops of the tension thread cleared out of said passage in the running part of the seam.

Advantageously and according to the invention, one moves transversely said portion of the tension thread being sewn from the stitch sewing by the stitching means, that is to say that the tension thread is moved between normal and clear position while continuing to sew the auxiliary threads by forming sewing stitches, without interrupting the means of quilting. It should be noted in this regard that as soon as said portion of tension wire extends upstream and at least immediately downstream of the stitching means, avoids, by this fact alone, almost any risk of blockage of the tension thread by the threads auxiliaries which cannot be stitched so as to pass through the thickness of the voltage. Indeed, the tension wire is clear of the passage and the action zone of the stitching means when it passes opposite and to the right of the stitching means. It is additionally possible to synchronize the stitching means and the displacement transverse of said portion of tension wire to prevent this displacement takes place simultaneously with a downward movement of a stitching needle.

In addition, sewing machines such as overcasters, overlockers, overlockers and shavers ... sewing on the edge of pieces include a work plate that extends laterally from a frame machine engine. In a first variant of the invention, applicable especially to form protruding strands of the tension wire at the ends of sewing, advantageously and according to the invention, to pass from the normal position in the disengaged position, said portion of the tension thread is moved laterally to the side of a work-holding plate and opposite to a motor frame of the sewing machine.

In a second variant of the invention, which can be combined with the previous one, which is applicable in particular to form loops of tension thread clear of the passage formed by the stitch partially current (i.e. between the two ends of the seam) of the seam, we vertically moves, in particular upwards, said portion of the tension wire in away from the top of the sewing piece and the work plate, beyond the area of action of the stitching means, in particular above the hook (s) upper looper (s) when at least one such upper looper hook is provided.

Furthermore, advantageously and according to the invention, for transversely move at least said portion of the tension wire, we move transversely at least one guide piece - of the tension wire arranged at upstream stitching means.

In an embodiment according to the invention, in particular applicable to form loops of the tension thread partially disengaged from said passage during sewing, a guide piece is moved transversely which is distinct from a pressing member. This guide piece is for example formed of a guide eyelet, crossed by the tension wire, and arranged at the downstream outlet of the member upstream presser. This embodiment is advantageously applicable to the second variant mentioned above.

In another embodiment according to the invention, which can be combined with the previous one, advantageously and according to the invention, one moves transversely an upstream pressing member carrying means for guiding the wire tension, and the workpiece is driven by a downstream drive member arranged immediately downstream of the stitching means. The upstream pressing device is especially a crowbar and / or a rotary member (wheel, roller, roller ...) driven in rotation by a specific or free motor member in rotation about an axis transverse. The downstream drive member is in particular a downstream presser foot and / or a downstream rotary member, or a downstream drive claw. This embodiment is advantageously applicable to the first variant mentioned above, to form strands protruding from the tension thread at the ends of the seam. So, advantageously and according to the invention, the upstream pressing member is moved laterally outside the area of action of the stitching means, and outside said passage. Advantageously and according to the invention, the member is also moved upstream presser vertically and upwards to avoid, in release position, any contact of this upstream pressing member with the workpiece.

It should be noted that, quite surprisingly, the invention provides for at least partially sewing while the pressing member upstream is released and is therefore no longer applied in a functional position on the part to be to sew. It turned out in practice that this is possible without any difficulty, thanks to the downstream drive member which can drive the workpiece and / or the auxiliary threads forming the stitch and / or the tension thread avoiding any malfunction, and in particular any jamming phenomenon.

The above-mentioned variants and embodiments can to be combined. Thus, according to the invention, an upstream pressing member can be moved to form strands protruding from the tension thread at the ends of the seam, and a separate guide piece can be moved laterally and / or vertically a pressing member (for example an eyelet) to form loops of the thread tension released from said passage in the running part of the seam.

Advantageously and according to the invention, one moves laterally said portion of the tension wire a sufficient distance to clear and move the tension wire laterally, on the one hand outside the area of action of the stitching means, and on the other hand outside the area of action of a first auxiliary wire cutting knife arranged downstream - in particular immediately downstream of the stitching means. This first knife is used to cut the auxiliary threads from the stitch without the risk of cutting simultaneously the tension wire.

• on déplace latéralement ladite portion du fil de tension d'une distance suffisante pour dégager et éloigner latéralement le fil de tension d'un premier couteau de sectionnement des fils auxiliaires, disposé à l'aval des moyens de piquage,
• on continue la couture du point de couture sur une longueur adaptée pour que le fil de tension soit dégagé latéralement du premier couteau de sectionnement aval,
• on actionne le premier couteau de sectionnement pour sectionner les fils auxiliaires du point de couture, et on interrompt la couture par les moyens de piquage,
• on déplace la pièce vers l'aval jusqu'à ce qu'une longueur correspondant à la somme des longueurs des brins de dépassement du fil de tension à former en début et en fin de couture,
• on engage la partie du fil de tension à sectionner pour séparer le brin de dépassement de fin de la pièce à coudre et le brin de dépassement de début d'une prochaine pièce à coudre, dans un deuxième couteau de sectionnement,
• on actionne le deuxième couteau de sectionnement,
• on replace en position normale les moyens de piquage, les moyens de guidage du fil de tension et ladite portion du fil de tension, pour la réception et la couture d'une prochaine pièce à coudre.

The invention further relates to such a method suitable for allowing a strand of tensioning thread, called a protruding strand, to protrude beyond a start end and beyond an end end of the seam formed by the stitch, characterized in that, at the end of the stitch:

• said portion of the tension wire is moved laterally by a sufficient distance to release and laterally move the tension wire away from a first knife for cutting the auxiliary wires, disposed downstream of the stitching means,
• the stitching of the stitch is continued over a suitable length so that the tension thread is released laterally from the first downstream sectioning knife,
• the first cutting knife is actuated to cut the auxiliary threads from the stitching point, and the stitching is interrupted by the stitching means,
• the part is moved downstream until a length corresponding to the sum of the lengths of the strands protruding from the tension thread to be formed at the start and at the end of the seam
• the part of the tension wire to be cut is engaged in order to separate the end protruding strand of the workpiece and the beginning protruding strand of a next sewing piece, in a second cutting knife,
• we operate the second sectioning knife,
• the stitching means, the tensioning thread guide means and said portion of the tensioning thread are returned to the normal position, for receiving and sewing a next piece to be sewn.

Advantageously and according to the invention, said portion is replaced tension thread in the normal position before operating the second knife sectioning.

Throughout the present application, the term " sew "any machine comprising at least one mechanism, called a sewing head, incorporating sewing means (stitching means, work-holding plate, drives, wire guides, ...). In general, a sewing machine consists of a supporting or built structure, at least one sewing head mounted on the frame, drive motor means carried by the frame (in general at least one electric motor), and control means (pedal (s), button (s), automaton (s) or digital system (s) and / or computer (s) ...) carried by the frame. In all text, the terms "sewing machine" can therefore designate either a sewing head insulated, i.e. a more complete set comprising at least one sewing head and other associated bodies as mentioned above.

The invention also extends to a sewing machine -in particular a traditional sewing machine modified after its manufacture - for setting work of a method according to the invention.

The invention therefore relates to a sewing machine comprising means for stitching at least one sewing point formed of auxiliary threads on a sewing piece, in a sewing direction, this stitch being of the type forming a passage extending in the direction of sewing, and means for guiding a wire, called tension wire, for its positioning in the passage simultaneously with the stitching of the auxiliary wires, so that this tension wire can slide longitudinally and / or laterally in this passage, characterized in that it comprises means, known as tension wire release means, to move transversely relative to the stitching means, at least one portion of the tension wire extending upstream and immediately downstream of the means of stitching, between a normal position for placing the tension thread in the passage, and a release position of said portion of the tension wire where it is inclined relative to the sewing direction and passes, opposite the means of stitching, outside the area of action of the stitching means and outside said passage, to allow in particular the sectioning independently of the wires auxiliary of the stitch and / or the tension thread by at least one knife sectioning arranged downstream of the stitching means, and / or the formation of loops tension thread released outside said passage in the running part of the seam.

Advantageously and according to the invention, the means of tension wire clearance are adapted to be able to move transversely to minus said portion of the tension thread during sewing of the stitch by the means of stitching.

The invention also advantageously relates to a machine comprising a motor frame and a work-holding plate extending generally over one side of the engine mount from the stitching means, characterized in that the tension wire release means are adapted to move laterally said portion of the tension wire on the side of the work-holding plate and opposite the engine mount, out of said passage, from the normal position to the release position.

As a variant or in combination, advantageously and according to the invention, the release means are adapted to move vertically, in particular upwards, said portion of the tensioning wire away from it upwards the piece to be sewn, beyond the area of action of the stitching means.

The invention also advantageously relates to a machine in which the stitching means comprise at least one needle, and comprising means for driving the sewing piece, characterized in that the means drive comprise at least one member, called downstream drive member, disposed immediately downstream of the needle, and in that the release means tension wire are adapted to transversely move at least a portion tension wire extending upstream from the downstream drive member.

Advantageously and according to the invention, the guide means of the tension wire comprise at least one upstream guide piece disposed at upstream of the stitching means and carried by support means suitable for ability to place guide piece in normal position where it guides tension thread in relation to the stitch, or in the thread release position tension in which it is moved transversely relative to the means of stitching, so that these means for supporting the upstream guide piece (s) act as means for releasing the tension wire.

Advantageously and according to the invention, the means of tension wire release include means adapted to be able transversely move at least one guide piece which is separate from a pressure member.

Advantageously and according to the invention, the means of tension wire release include at least one actuator to double action - notably a pneumatic cylinder or an electromagnet - allowing to transversely move the tension thread between the normal position and the position tension wire clearance, and vice versa.

According to a variant, advantageously and according to the invention, the tension wire guide means comprise at least one guide piece lateral of the tension wire and of the means for supporting this guide part by relative to a frame of the machine, and the means for supporting this guide part are adapted to be able to place it in the normal position in which it guides the wire tension in relation to the stitch, or in the side release position of the tension wire in which it is moved laterally relative to the means of stitching, so that these means for supporting the guide piece act as tension wire release means.

According to another variant, which can be combined with the previous, the means for supporting an upstream guide part are adapted to ability to place guide piece in normal position where it guides tension thread in relation to the stitch, or in the vertical release position tension wire in which the guide piece is moved vertically, especially upwards, relative to the stitching means.

The invention also relates to a machine comprising means for guiding the tension thread formed and / or carried by a pressing member upstream drive of the sewing piece, and means for supporting the member upstream presser relative to a machine frame; suitable for applying, in active position, the upstream pressing member in contact with the workpiece, characterized in that the support means are adapted to be able to place the pressing member upstream in the tension wire release position in which the pressing member upstream and the tension wire guide means are moved laterally by relative to the stitching means, so that these means for supporting the member upstream presser acts as means for releasing the tension wire.

• un bras articulé par une extrémité aval au bâti de la machine de façon à pouvoir pivoter autour d'un axe vertical et autour d'un axe horizontal transversal et portant l'organe presseur amont avec les moyens de guidage du fil de tension à son extrémité amont,
• un organe d'actionnement double action porté par le bâti et ayant une tige d'actionnement mobile en translation,
• une biellette de liaison entre le bras et la tige d'actionnement.

Advantageously and according to the invention, said means for supporting the upstream pressing member comprise:

• an arm articulated by a downstream end to the frame of the machine so as to be able to pivot around a vertical axis and around a transverse horizontal axis and carrying the upstream pressing member with the means for guiding the tension thread at its end upstream
• a double action actuating member carried by the frame and having an actuating rod movable in translation,
• a connecting rod between the arm and the actuating rod.

The actuator is mounted on the frame so that the actuating rod can exert, in the normal position, a pressing pressure on the arm in the direction of application of the upstream pressing member on the workpiece.

Advantageously and according to the invention, the connecting rod has a twist so as to generate, from a translational movement accompanied by a proper rotation of the actuation, movements of lateral displacement of the upstream pressing member by pivoting of the arm around the vertical axis, and of vertical displacement of the upstream pressing member by pivoting of the arm around the transverse horizontal axis.

Advantageously and according to the invention, the machine comprises a first knife for cutting the auxiliary wires, arranged downstream of the means of stitching, and said tension wire release means are adapted for move at least said portion of the tension thread laterally by a distance sufficient to clear the tension thread laterally from the first knife sectioning of auxiliary wires.

Advantageously and according to the invention, the machine comprises two wire cutting knives, the first disposed downstream of the means of stitching for cutting the auxiliary threads of the overlock, the second disposed at the downstream of the first at a distance corresponding to the length of a strand of wire tension, said overhang strand, to be left beyond a start end of the seam formed by the stitch on a next piece of sewing.

Advantageously and according to the invention, the first knife is disposed immediately downstream and near the downstream drive member.

The invention makes it possible to make fully automatic the method according to the invention. To do this, advantageously and according to the invention, the machine includes means for automatically guiding the workpiece by relative to the guide means and, where appropriate, to the knife (s) sectioning, and automatic control means of the means of release of the tension wire and, if necessary, of the knife (s) sectioning. Advantageously and according to the invention, the guide means automatic sewing piece include a suitable gripper robot and programmed to move the piece to be sewn on a work holding plate of the machine as the seam is executed. Advantageously and according to the invention, the means for automatically guiding the workpiece and the means for automatic control of the tension wire release means include a programmable digital system adapted and programmed to check, as and when sewing, the stitching means, the movements of the workpiece, the tension thread release means and the sectioning knife (s).

The execution of the seam according to the invention can be fully automatic and be part of an automatic dressing process objects such as seat upholstery.

The invention is more particularly and advantageously applicable to the execution of a stitch which is an overlock, in particular an overlock with one, two, three, four or five sewing threads (auxiliary threads). The machine according to the invention is then advantageously an overlocker, in particular an overlocker stitcher.

The invention automatically allows sewing during disengage the sliding tension thread from the passage formed by the stitch, and put it back in normal position to form either loops of tension thread clear of the passage in the main part, i.e. the ends of the tension wire beyond the ends of the passage. The loops in the running part allow by example the hanging of the tension wire on hooks or studs of an object to garnish and / or exert a tension in the running part of the edge of the piece. The end strands provide traction on the tension wire and block the tension wire in the stretched state. It should be noted that the formation of these loops and / or these end strands do not deprive the tension wire of its sliding possibilities in the passage. Indeed, the invention makes it possible to prevent the tension wire from being crossed and blocked by the auxiliary sewing threads.

The invention further relates to a method and a machine. characterized in combination by all or some of the characteristics mentioned above or below.

• la figure 1 est une vue schématique partielle en perspective d'une machine selon l'invention en position normale du fil de tension,
• la figure 2 est une vue similaire à a figure 1 illustrant la machine en position dégagée du fil de tension,
• les figures 3 à 9 sont des vues schématiques partielles de dessus illustrant différentes étapes, dans l'ordre chronologique, d'un procédé selon l'invention,
• les figures 10 et 11 sont des vues schématiques partielles de devant illustrant les moyens de dégagement du fil de tension en position normale et, respectivement, en position dégagée, d'une machine selon l'invention,
• les figures 12 et 13 sont des vues schématiques partielles de dessus illustrant les moyens de dégagement du fil de tension en position normale et, respectivement, en position dégagée, d'une machine selon l'invention,
• la figure 14 est une vue schématique partielle de côté illustrant les moyens de piquage et les moyens de dégagement d'une machine selon l'invention,
• la figure 15a est une vue schématique en coupe axiale des moyens spécifiques de guidage en rotation propre de la tige d'actionnement des moyens de dégagement du fil de tension d'une machine selon l'invention,
• la figure 15b est une vue similaire à la figure 15a, représentée sans la tige d'actionnement,
• la figure 16 est une vue schématique partielle de dessus d'une machine selon l'invention,
• la figure 17 est une vue schématique en perspective d'ensemble d'une machine automatique selon l'invention,
• les figures 18 à 20 sont des vues schématiques partielles de dessus illustrant respectivement deux variantes de réalisation des moyens de dégagement du fil de tension d'une machine selon l'invention.
• les figures 21a, 21b et 21c sont des vues schématiques partielles en coupe verticale transversale illustrant les moyens de dégagement du fil de tension respectivement en position de dégagement vertical, en position normale de couture, et en position de dégagement latéral, de la machine selon l'invention conforme à la variante de la figure 20,
• la figure 22 est une vue schématique partielle de côté illustrant les moyens de piquage et les moyens de dégagement, en position de dégagement vertical, d'une machine selon l'invention conforme à la variante des figures 20, 21a, 21b et 21c.

Other objects, advantages and characteristics of the invention will appear on reading the following description which refers to the appended figures in which:

• FIG. 1 is a partial schematic perspective view of a machine according to the invention in the normal position of the tension thread,
• FIG. 2 is a view similar to FIG. 1 illustrating the machine in the disengaged position of the tension wire,
• FIGS. 3 to 9 are partial schematic views from above illustrating different stages, in chronological order, of a method according to the invention,
• FIGS. 10 and 11 are partial schematic front views illustrating the means for releasing the tension wire in the normal position and, respectively, in the released position, of a machine according to the invention,
• FIGS. 12 and 13 are partial schematic views from above illustrating the means for releasing the tension wire in the normal position and, respectively, in the released position, of a machine according to the invention,
• FIG. 14 is a partial schematic side view illustrating the stitching means and the release means of a machine according to the invention,
• FIG. 15a is a schematic view in axial section of the specific means for guiding its own rotation of the actuating rod of the means for releasing the tension wire of a machine according to the invention,
• FIG. 15b is a view similar to FIG. 15a, shown without the actuating rod,
• FIG. 16 is a partial schematic view from above of a machine according to the invention,
• FIG. 17 is a schematic overall perspective view of an automatic machine according to the invention,
• Figures 18 to 20 are partial schematic views from above respectively illustrating two alternative embodiments of the release means of the tension wire of a machine according to the invention.
• Figures 21a, 21b and 21c are partial schematic views in vertical cross section illustrating the tension wire release means respectively in the vertical release position, in normal sewing position, and in lateral release position, of the machine according to the invention according to the variant of FIG. 20,
• Figure 22 is a partial schematic side view illustrating the stitching means and the release means, in the vertical release position, of a machine according to the invention according to the variant of Figures 20, 21a, 21b and 21c.

The sewing machine according to the invention shown in the figures is an overlock sewing machine, i.e. a machine suitable for cutting the edge of a sewing piece 1 (flexible cover of fabric, leather, synthetic or other materials) using a side knife 2, and execute a overlock stitch 3 with auxiliary sewing threads 4. As auxiliary wires 4, we can use transparent nylon threads (330 denier) of small diameter or any other industrial sewing thread.

EP-0 223 312 and US-4 735 097, the content of which is incorporated with reference to the present application, already describe the general characteristics of such a sewing machine and of the method of covering objects, such as seat upholstery, which can be implemented using such a machine. In consequence, only the characteristics specific to the invention object of the present request, will be detailed below.

The sewing machine includes stitching means 5, 6, 7, which in the example shown, are formed by a needle 5, a looper hook upper 6, and a lower hook 7. These means 5 to 7 for stitching allow make a three-thread overlock stitch. The invention nevertheless also extends to any another overlock point, the machine also being equipped with stitching means corresponding, or more generally, to any stitch for making a longitudinal passage P in which a tension wire 8 distinct from the auxiliary wires (i.e. which is not one of the threads forming said stitch) can be introduced, this tension wire 8 being able to slide longitudinally and / or laterally in passage P. The tension thread 8 can be formed of a nylon thread, or of a cord or cord, or an elastic or other thread. It is generally larger diameter than the auxiliary wires, although the reverse is also possible. The machine sewing also includes means 9 to 10 for driving the part 1 to be sewn in and through the stitching means 5 to 7. The machine basically includes a motor frame 12 and a work holding plate 13 extending generally on one side engine mount 12 from the stitching means 5. Means 9 to 11 drive drive part 1 in a sewing direction D which extends the along the side of the engine mount 12 from which the work plate 13 extends laterally. The means 9 to 11 of drive comprise a set of claws motorized lower 9 (i.e. driven by a machine motor) passing through the work-holding plate 13 by suitable lights, a member upstream presser 10 disposed above the work-holding plate 13 upstream of the stitching means 5 to 7 for applying the piece 1 to be sewn against the claws 9 lower, and a downstream drive member 11 disposed above the plate book holder 13 immediately downstream of the stitching means 5 to 7 for driving piece 1 to be sewn after stitching. The upstream pressing member 10 is, in the example depicted, a traditional crowbar. The downstream drive member 11 shown is a motorized upper claw synchronized with part of the claws 9 lower disposed downstream of the stitching means 5 to 7. Alternatively no shown, the downstream drive member 11 can also be formed with a single foot presser which presses the piece 1 on the lower claws 9.

The side cutter 2 extends immediately upstream of the stitching means 5 to 7 for cutting or shaving the edge of the piece 1 before the execution of the overlock stitch.

The upstream pressing member 10 carries a guide piece 14 of the tension wire 8. This guide piece 14 is, in the example shown, in the form of a bent tube section extending over the side of the presser foot 10 oriented towards the engine mount 12, so that the tension wire is immediately guided upstream of the stitching means 5 to 7 parallel to the sewing direction D, in the axis of the passage P produced by the overlock point. Tension wire 8 is brought to the guide piece 14 from a reserve coil by at least one guide member 15 secured to the engine mount 12.

The machine also includes a first knife 16 of sectioning (for example a knife reference C-GEX T07, sold by the C-GEX SYSTEM'S (France)) disposed immediately downstream of the means 9 to 11 of training and means 5 to 7 of stitching, namely immediately downstream of the downstream drive member 11. The machine also includes a second knife 17 (for example an offset knife sold by the company C-GEX SYSTEM'S (France)) sectioning arranged in the axis of the first knife 16 in the sewing direction D, downstream, at a distance d1 from the first knife 16 corresponding to the desired length for a protruding strand 18 of the tension 8 to be left free beyond an end 19 at the start of the overlock stitch 3.

Each of the sectioning knives 16, 17 is motorized with using an actuating motor member 20, respectively 21, which can be a pneumatic cylinder, an electromagnet, or any other similar actuating member. Each knife 16, 17 is for example constituted by a movable blade which can pivot about an axis parallel to the sewing direction D, and a fixed blade extending at level of the work-holding plate 13 in the transverse direction by crossing the sewing direction D. Thus, the movable and fixed blades act in the manner of scissors for cutting the wires passing over the fixed blade, the movable blade being driven to pivot down.

The upstream pressing member 10 with the guide piece 14 is carried by support means 22, 23, 24 which comprise an arm 22 articulated at the frame 12 of the machine, an actuating member 23 with double action (i.e. can be controlled in two opposite directions) whose body 26 is carried by the frame 12, and having an actuating rod 25 movable in axial translation in one direction or in the other relative to the frame 12, and a connecting rod 24 connecting the arm 22 and the actuating rod 25. The arm 22 extends generally parallel to the sewing direction D, above work-holder 13, at least substantially in a horizontal direction. The downstream end 29 of the arm 22 is articulated to the frame 12 of the machine, by means of articulation, in a suitable manner so that the arm 22 can pivot around a vertical axis 27 and around an axis transverse horizontal 28. The actuating member 23 is for example a jack double action tire whose body 26 is carried by the frame 12 according to a direction at least substantially vertical, slightly inclined downwards and towards upstream in the example shown. The upstream end 30 of the arm 22 carries the member upstream presser 10 with the guide piece 14 of the tension wire 8.

The free end of the actuating rod 25 of the member actuator 23 is adapted to be able to exercise, in normal position, a pressing pressure on the arm 22 in the direction of application of the pressing member upstream 10 on the part 1 to be sewn, that is to say downwards and towards the work-holding plate 13. The end of the actuating rod 25 indeed comes to bear against the arm 22 when the actuating rod 25, oriented downward relative to the body 26, is in the fully deployed state. The end of the actuating rod 25 is advantageously formed of a flat 31 defining a vertical lateral face against which the articulated arm 22 abuts laterally. So the actuating rod 25 also limits the possibilities of pivoting of the arm 22, and therefore of the member upstream presser 10 horizontally to the frame 12. The flat 31 also defines a shoulder which bears on the upper edge 20 of the arm 22 to apply the upstream pressing member vertically downwards as described above.

The connecting rod 24 has a twist in its direction longitudinal, so as to generate, from a translational movement accompanied by a proper rotation (around its axis of translation) of the rod actuation 25, lateral displacement movements of the pressing member upstream 10 by pivoting of the arm 22 around the vertical axis 27, and displacement vertical of the upstream pressing member 10 by pivoting of the arm 22 about the axis horizontal transverse 28. The link 24 is connected to the arm 22 by a light 32 longitudinal formed in this rod 24, in which a slide 33 integral with the arm 22 can slide. The slide 33 is for example simply consisting of a head screw passing through the lumen 32 and engaged in a thread corresponding arm 22. The connecting rod 24 is also fixed integral with the actuating rod 25 by a collar 34 tightened by a screw.

With such a mechanism, when the actuating rod 25 goes back into the cylinder body 26, the torsion of the connecting rod 24 causes a pivoting movement of the arm 22 around the vertical axis 27, laterally at the opposite of the frame 12, and around the transverse horizontal axis 28 vertically towards the high.

It should be noted that during this movement, the actuating rod 25 turns on itself around its longitudinal axis. This rotational movement clean, and the pivoting of the arm 22 around the vertical axis 27 may result from the torsion of the connecting rod 24 and / or be obtained by means 35, 36 specific guide in proper rotation of the actuating rod 25 during these translational movements. In the example shown, a sleeve 35 is fixed secured to the actuating rod 25 by any appropriate means (keys, screws radial ...), this sleeve 35 carries at least one radial stud 51 extending in projection outwards and which cooperates with inclined bearing surfaces 52 of shapes suitable provided in a socket 36, itself carried by the frame 12 which it is united. The actuating rod 25 and its sleeve 35 pass axially through the socket 36. The stud 51 of the sleeve 35 and the bearing surfaces 52 of the socket 36 are adapted to cause a proper rotation of the rod 25 about its axis in a direction or in the other when the latter moves in translation, in one direction or the other.

Thus, the means 22, 23, 24 for supporting the pressing member upstream 10 act, with the guide piece 14, of wire release means of tension 8, and are adapted to move transversely, laterally, opposite of the engine mount 12, and vertically a portion 37 of the tension wire 8 which extends between the downstream drive member 11 and the guide piece 14. This portion 37 of the tension wire is that which extends on the one hand immediately downstream of the means 5, 6, 7 stitching, to the downstream drive member 11, and immediately upstream means 5, 6, 7 for stitching, up to the guide piece 14. In other words, this portion 37 of the tension wire is that which extends immediately downstream and towards upstream from the stitching means 5, 6, 7. This portion 37 of the tension wire is that which passes through the action zone of the stitching means 5, 6, 7, and which is in sewing classes. The means 14, 22, 23, 24 of release are adapted so that the guide piece 14 can be placed either in the normal position where it guides the wire tension 8 in the sewing direction D in the passage P as described above, either in the release position in which the portion 37 of the tension thread 8 is moved laterally and vertically upward relative to the means of stitching 5, 6, 7, and inclined relative to the sewing direction D to pass, in view of the stitching means 5, 6, 7, outside the area of action of the means 5, 6, 7 of stitching and outside the passage P formed by the overlock stitch.

In the variant shown in Figures 1 to 11, all of the tension wire 8 extending upstream of the downstream drive member 11 and up to the (the) guide piece (s) 15 integral with the frame 12 is moved laterally by the means 22, 23, 24 of release. It should be noted, however, that other variants of realization are possible since at least a portion 37 of the tension wire extending upstream from the downstream drive member 11, immediately at downstream and upstream of the stitching means 5, 6, 7 can be moved laterally to release the tension thread 8 from the action zone of the stitching means 5, 6, 7 and outside passage P and the first knife 16.

The process implemented with such a machine is shown in Figures 3 to 11.

Figures 1, 3 and 10 show the upstream pressing member 10 and the guide piece 14 in normal position, the tension thread 8 being normally engaged in passage P defined by the overlock 3 along the edge of the piece 1 to to sew. From this normal position, and even during sewing, i.e. without interruption of the stitching means 5 to 7, it is possible to place, by actuation of the jack 23, the upstream pressing member 10 and the guide piece 14 in the position release (Figures 2, 4, 5 and 11). Therefore, the portion 37 of the tension wire 8 extending between the downstream drive member 11 and the guide piece 14 present a lateral and upward inclination with respect to the sewing direction D. It is at note that this provision in particular avoids the sting of the tension wire 8 by the needle 5 since the entire portion 37 of the tension thread 8 extending upstream at from the downstream drive member 11 is moved laterally and inclined by relative to the sewing direction D. The tension thread 8 is therefore not crossed by one auxiliary threads 4 of the seam.

Figure 5 shows the layout obtained after training a few additional overlock stitches, the intersection between the portion 37 of the thread of tension 8 and the seam of the overlock stitch 3 being moved downstream, the portion 37 tension wire being released laterally from the downstream drive member 11 and first sectioning knife 16. As we can see, in this position the portion 37 of the tension thread 8 is released from this first knife 16 which, when is actuated as shown in figure 5, only cuts the overlock stitch 3, i.e. as the auxiliary threads 4, to form an end end 53 of the overlock stitch 3 for piece 1 to be sewn at the end of the seam, and a start end 19 of the stitch overlock 3 for the next sewing piece 1.

In addition, it should be noted that by performing these overlock stitches terminals before sectioning the auxiliary threads 4 from the overlock stitch, you can release the part 1 to be sewn at the end of sewing out of the stitching means 5, 6, 7, the upstream pressing member 10 is no longer applied to the part 1 to be sewn. In the arrangement of FIG. 5, the part 1 to be sewn is therefore released laterally from the means 5, 6, 7 for stitching and the downstream drive member 11. It should be noted that in this arrangement, any friction wear between the upstream pressing member is avoided 10 and the claws 9, despite the absence of fabric.

It should also be noted that after clearing the tension wire 8 out overlock 3, this overlock 3 can still be sewn on piece 1 on a certain length. In FIG. 5, a few overlock stitches have been depicted on the piece 1, extended by a few overlock stitches stitched out of piece 1. In variant not shown, the upstream pressing member 10 can be kept in position free in the running part of the seam overlock (and not at the ends) then continue sewing overlock 3 on piece 1, then replace the upstream presser 10 in normal sewing position to continue sewing overlock 3. thus a strand of tension thread 8 released from the overlock 3 in the running part, that is to say a tension wire loop 8 which can be used for example for hanging and tension of part 1 on a support.

In Figure 6, a subsequent position is shown in which the upstream portion 37 of the tension thread 8 released outside the passage P of the overlock 3 is brought opposite and into the second cutting knife 17, then cut by this second knife 17. To facilitate alignment of the tension wire 8 in this second knife 17, the upstream pressing member 10 has previously been brought back and the guide piece 14 in normal position (by controlling the jack 23 in the direction of descent of the actuating rod 25). Preferably, as soon as the wires auxiliaries 4 of the overlock stitch 3 are cut by the first knife 16 (FIG. 5), the stitching means 5, 6, 7 are interrupted and the drive means 9, 10, 11.

As seen in Figure 6, the part 1 is then provided with a protruding strand 38 of the tension thread 8 which is left free outside the overlock 3 at the end sewing. The length d2 of this protruding strand 38 depends on the length of the portion of tension wire 8 which has been scrolled downstream from and beyond the second sectioning knife 17.

The part 1 also includes a protruding strand 18 which was previously formed at the start of the seam, the length of which d1 depends on the distance between the second knife 17 and the first knife 16.

Advantageously, the second knife 17 is fixed on the machine so as to allow adjustments to the position of the second knife 17, and therefore of this length d1.

To do this, the second knife 17 is carried entirely (movable blade and fixed blade) by a frame 54 (Figure 16) which is slidably mounted on a runner 55 extending parallel to the sewing direction D downstream from the engine mount 12 of the machine to which it is fixed. A tightening button 56 to wheel locks the frame 54 in place on the slide 55 after adjustment. The fixed blade of the knife 17 is formed by a plate 57 placed on the work-holding plate 13. The frame 54 also advantageously carries a drive member actuation 21 of the knife 17. When the frame 54 is moved along the slide 55, modify the distance d1 while keeping the second knife 17 aligned to the first knife 16 in the sewing direction D.

From the position shown in Figure 6, you can start sewing a new piece 1 that is engaged under the presser foot presser 10 as shown in FIG. 7.

Advantageously, to ensure that the tension wire 8 exceeds laterally the vertical of the needle 5 towards the engine mount 12 when the guide piece 14 in normal position, the tension of the auxiliary thread 4 of the overlock 3, in particular at least the tension of the auxiliary thread 4 needle, and auxiliary thread 4 of upper hook. To do this, the machine according to the invention is provided with a double-acting actuator, such as a jack tire 39 whose actuating rod carries at least one shim 40 adapted to be able to engage between the pressure washers adjusting the tension of the thread 4 of needle and upper hook (Figure 1). In normal position, the wedge of thickness 40 is released out of these pressure washers, so that the tension wires and the one obtained in the traditional way by the settings made on the machine. When the actuator 23 for actuating the release means is actuated in the direction of return of the guide piece 14 in the normal position, the jack 39 carrying the wedge 40 is simultaneously actuated to engage the wedge 40 thickness, in the pressure washers of the needle thread and the hook thread upper, and fully relax the auxiliary wires 4. In this way, the tension 8 exceeds the needle 5 towards the engine mount 12 or abuts against this needle 5 and will overtake it on its next ascent. This is to avoid the passage of the needle 5 through the tension thread 8 and therefore the blocking of this thread tension 8 on the part 1 which would hamper its possibilities of later sliding in the passage P of overlock 3.

When you start sewing a new piece 1 as shown in Figure 7, the tension wire 8 is not always engaged under the member downstream drive 11, but can be as shown in the figures, above of this downstream drive member 11, which is generally in the form of a plate. When we start sewing overlock 3, as shown in figure 8, the strand of overshoot 18 is driven under the downstream drive member 11, and is thus brought naturally bypass it as shown in Figure 9. We thus arrive in all the cases in the position shown in figure 9 where the seam can be continued and completed as described above.

After sectioning of overlock stitch 3 by the first knife 16, and until the tensioning wire 8 is cut by the second knife 17, the part 1 is moved downstream so that a length corresponding to the sum d1 + d2 of the lengths of the protruding strands 18, 38 of the tension thread at the start and at the end of the seam be deployed and extend downstream from the first knife 16. These movements of the part 1 on the work-holding plate 13 and relative to the machine can be obtained by means 41 to 44 for automatically guiding the sewing piece 1 (figure 17). These means 41 to 44 for example consist of a gantry 41 extending in particular above the work-holding plate 13 and carrying a vertical column 42 at the lower end of which is fixed a tray 43 provided with means for gripping the part 1, the assembly being controlled in its movements by a 44 digital programmable system (PLC, system computer science...). The gantry 41 is adapted to allow movement in translation of the column 42 and of the plate 43 in the two horizontal directions. The column 42 and the plate 43 are adapted so that the latter can on the one hand be controlled, relative to the work-holding plate 13, in proper rotation around a vertical axis, and on the other hand be controlled in upward or downward translations in the vertical direction. The assembly therefore constitutes a suitable gripping robot and programmed to move part 1 on the work holding plate 13 of the machine to as you sew. This robot is also suitable for taking a part 1 on a pile 58 of waiting sewing pieces, and engage it under the pressing device upstream 10 of the machine at the start of sewing. This robot is also programmed to move piece 1 at the end of sewing by the distance d1 + d2, using the tension 8 in the second knife 17 as described above, then to place each piece sewn on a stack 59 of pieces sewn. The digital system programmable 44 is also programmed to control the various organs 23, 39, and the general operation of the machine, in particular the drive means 9 to 11, and the stitching means 5 to 7.

The plate 43 is provided with means for gripping the parts 1 allowing to take one, and only one piece 1 from the stack 58 of pieces to sew, then release piece 1 on pile 59 after sewing. These means of gripping can be done in any suitable way, depending on the nature of the parts 1, by suction cup (air suction), by fabric gripping claws (such as claws reference SCH 20 or ST 36 sold by SOMMER AUTOMATIC (Germany)), by repositionable self-adhesive, by means hooking type with buckles and claws (VELCRO, registered trademark), by static electricity, by pinching ...

The creation and programming of a gripper robot and its associated programmable digital system as described above are fine known per se and do not pose any particular difficulties. In particular, the whole can be achieved by electric stepper motors, generating each of movements, encoders and programming of digital controls traditional.

The invention can be the subject of several variants with respect to to the embodiment described above. In particular, if it is advantageous to laterally disengage the upstream presser foot 10 simultaneously with the guide piece 14, the subsequent drive from the overlock stitch 3 (without tension thread 8 or piece 1) being obtained satisfactorily by the downstream drive member 11, it is also possible to release the tension wire 8 without moving the member upstream presser 10.

Thus, in a first variant (FIG. 18), the means of release are formed by a horizontal cylinder 45 whose body 46 is carried by the frame 12, and whose actuating rod 47 is connected to a guide eyelet 48 crossed by the tension wire 8. This eyelet 48 is disposed, in the normal position, at the downstream outlet of the guide piece (tube) 14 carried by the upstream pressing member 10; The eyelet 48 is nevertheless provided upstream with the means 5, 6, 7 for stitching. The eyelet 48 guide is thus itself a lateral guide piece of the tension wire 8 which is arranged downstream of the upstream pressing member 10 and of the guide piece 14 which it door, and upstream means 5, 6, 7 of stitching, so that this eyelet 48 of guide moves laterally the portion of the tension wire 8 extending between the member downstream drive 11 and the output of the guide piece 14 carried by the member upstream presser 10. The jack 45 is adapted to be able to place the eyelet 48, either in normal position opposite the outlet of the guide piece 14, either in a laterally released position in which the eyelet 48 is laterally spread at the opposite of the frame 12 and beyond the upstream pressing member 10, to move laterally the portion 37 of tension wire 8 (Figure 18). The upstream pressing device 10 must have an appropriate shape to allow movement in translation transverse of the actuating rod 47 actuating the actuator 45 and the eyelet 48. In particular, the upstream pressing member 10 is carried by a support arm 49 which must be positioned sufficiently upstream so that the eyelet 48 moves downstream of this support arm 49, the tension wire 8 not passing upstream of this arm 49 of support.

In another variant of the invention (Figure 19), the organ upstream presser 10 is carried by a fixed support arm 49, by built protractor 12, and the articulated arm 22 carries a guide piece 61 in the form of a tube, similar to the guide piece 14 of the first variant, but which is dissociated from the member upstream presser 10. The arm 22 is controlled in its movements by the jack 23 and the connecting rod 24 as described for the first variant. The support arm 49 of the upstream pressing member 10 must then extend between the guide piece 61 and the engine mount 12, so that the guide piece 61 of the tension wire 8 can be move laterally freely relative to the upstream pressing member opposite the frame 12 as shown in FIG. 19. The shape of the upstream pressing member 10 is slightly modified to extend further upstream of the side cutter 2 and laterally on the side of the frame 12 than in the embodiments previously described.

The variants of Figures 18 and 19 allow to identify transversely the tension wire 8 while retaining the guiding of the part 1 to sew by the upstream pressing member 10. It is thus possible in particular to form loops tension thread in the current part of the seam ensuring precise guidance of the piece 1 to be sewn by the upstream pressing member 10. The stitching of the tension thread 8 by the needle 5 during the lateral displacement of the guide piece 14, 48, 61 is almost improbable, and can be avoided by proper synchronization of the actuating member 23, 45 with the movements of the needle 5.

The variant of Figures 20 to 22 has the advantage additional to be able to avoid with certainty this stitching (crossed) of the tension 8 by needle 5 without requiring synchronization. In addition, with this variant, one can pre-orient the loops released from passage P more or less vertically with respect to part 1 to be sewn.

In this variant, an eyelet 48 for guiding the tension thread 8 is, as in the variant of FIG. 18, crossed by the tension wire 8 and arranged at downstream of the downstream outlet of the guide piece 14 carried by the upstream pressing member 10 and upstream of the means 5, 6, 7 for stitching.

This eyelet 48 is formed at the free end of a rod 63 articulated freely pivoting about a horizontal axis 64 parallel to the direction longitudinal stitching D, at the end 65 of a screw / nut system 66 carried by the actuating rod 67 of a first horizontal cylinder 68 with double action, the body of which 69 is fixed to the frame 12. The screw / nut system 66 allows the length between the end 65 carrying the axis 64 of articulation of the rod 63, and a support arm 70 carried by the actuating rod 67. The support arm 70 carries the body 71 of a second double-acting cylinder 72 whose actuating rod 73 is articulated to a rod 74 integral, in rotation about the axis 64, with the rod 63 carrying the eyelet 48. The second cylinder 72 is therefore carried by the actuating rod 67 of the first cylinder 68. The rod 74 extends upwards, at an angle of approximately 90 ° with the rod 63 carrying the guide eyelet 48.

In the normal sewing position (figure 21b), the upper actuator 67 of the first cylinder 68 is retracted and the actuation rod 73 of the second cylinder 72 is deployed. The rod 63 extends at least substantially horizontally, and the guide eyelet 48 and the tension thread 8 are in position normal sewing.

When the second cylinder 72 is actuated from this normal position, its actuating rod 73 retracts, which makes it pivot towards the high around the axis 64 the rod 63. The eyelet 48 is then moved upwards (Figure 21a). The amplitude of this displacement is sufficient for the portion 37 of the tension wire 8 extending between the downstream drive member 11 and the eyelet 48 passes entirely above the area of action of the stitching means 5, 6, 7, in particular above the upper hook 6 (figure 22). Therefore, the tension wire 8 is no longer sewn in overlock 3 and is released vertically upwards. Later, the second cylinder 72 is actuated to deploy its actuating rod 73, which returns the eyelet 48 to the normal sewing position, and the tension thread 8 is reintroduced in passage P. A loop 62 of tension wire 8 thus released from the passage P not passing under the needle 5 to form the loops 62, there is no risk of pricking the tension thread 8 and blocking it, regardless of when the first cylinder 68 is actuated. The loops 62 thus formed extend at least substantially vertically upwards from part 1, and are thus pre-oriented. This variant is more particularly applicable in the case of a wire elastic tension 8. The loops 62 regularly distributed along the edge of the part 1 allow to garnish and dress with this part 1 an object endowed with hooks or attachment studs, the part 1 being tensioned by the tension wire 8.

As seen in Figure 21c, we can also form loops or strands of ends of the tension wire 8 by laterally disengaging the tension 8, as in the variant of FIG. 18, by actuating the first jack 68 to deploy its actuating rod 67, from the normal sewing position.

In another possible variant of the invention (not shown), the tension wire guide piece 8 may be disposed between the support 49 of the upstream presser foot 10 and the engine mount 12, or immediately upstream of the upstream presser foot 10. It is possible to program a movement of upward movement of the upstream presser foot 10 simultaneously with the movement lateral of the guide piece which will then pass under this upstream presser foot 10. In this latter variant, it is however necessary to provide a first member actuator for displacements of the guide piece, and a second member actuation can be controlled by the digital system 44 to raise the upstream presser foot 10.

however, it should be noted that in all variants of the invention, the machine according to the invention can be easily obtained by simple modification and addition to a traditional overlock sewing machine such as that described and represented in EP-0 223 312 and / or US-4 732 097. It suffices indeed to modify the support device for the upstream presser foot 10, and to add the downstream drive member 11 with its associated drive means, by coupling it to the drive means of the lower feed dogs 9.

Furthermore, the invention may be the subject of other variants of embodiment, In particular, the invention is applicable with other sewing stitches than an overlock and therefore to other machines than overlockers, as soon as the seam forms a passage in which a tension thread can be inserted.

Claims (27)

1. A method for sewing, on a piece (1) to be sewn and according to a direction of sewing, a stitch (3) consisting of threads, known as auxiliary threads (4), by means (5, 6, 7) for picking up, of a sewing machine, this stitch (3) being of the type which forms a passage (P), which extends in the direction of sewing (D), with a thread, which is known as the tension thread (8), which is guided and put into position in this passage (P) simultaneously with picking up of the auxiliary threads (4), such as to be able to slide longitudinally and/or laterally in this passage (P), wherein there is displaced transversely relative to the means (5, 6, 7) for picking up, at least one portion (37) of the tension thread (8), which extends from upstream and immediately to downstream from the means (5, 6, 7) for picking up, between a normal position for putting the tension thread (8) into position in the passage (P), and a position for release of the said portion (37) of the tension thread (8), in which the latter is inclined relative to the direction of sewing (D) of the stitch, and passes opposite the means (5, 6, 7) for picking up, beyond the area of action of the means (5, 6, 7) for picking up, and beyond the passage (P), in order, in particular, to permit cutting off independently of the auxiliary threads (4) of the stitch (3) and/or of the tension thread (8), by at least one cutting blade (16, 17) which is disposed downstream from the means (5, 6, 7) for picking up, and/or formation of loops (62) of the tension thread (8), which are released from the said passage (P), whilst sewing is taking place.
2. A method as claimed in claim 1, wherein at least the said portion (37) of the tension thread (8) is displaced transversely during sewing of the stitch (3), by means (5, 6, 7) for picking up.
3. A method as claimed in either of claims 1 or 2, wherein, in order to transfer from the normal position to the position of release, the said portion (37) of the tension thread (8) is displaced laterally to the side of a work-holder plate (13), and opposite a motor frame (12) of the sewing machine.
4. A method as claimed in any one of claims 1 to 3, wherein, in order to transfer from the normal position to the released position, the said portion (37) of the tension thread is displaced vertically by being moved away upwards from the piece (1) to be sewn, beyond the area of action of the means (5, 6, 7) for picking up.
5. A method as claimed in any one of claims 1 to 4, wherein, in order to displace the said portion (37) of the tension thread transversely, there is displaced transversely at least one guiding part (14, 48) for the tension thread (8), which is disposed upstream from the means (5, 6, 7) for picking up.
6. A method as claimed in claim 5, wherein there is displaced transversely at least one guiding part (48, 61), which is distinct from a presser unit.
7. A method as claimed in any one of claims 1 to 6, wherein there is displaced transversely an upstream presser unit (10) of the machine, which supports means (14) for guiding the tension thread (8), and the part (1) is moved by a downstream movement unit (11), which is disposed immediately downstream from the means (5, 6, 7) for picking up.
8. A method as claimed in claim 7, wherein the upstream presser unit (10) is displaced laterally such as to release the said portion (37) laterally beyond the area of action of the means (5, 6, 7) for picking up, and beyond the passage (P), and the upstream presser unit (10) is also displaced vertically and upwards, in order, in the release position, to prevent any contact of this upstream presser unit (10) with the part (1) to be sewn.
9. A method as claimed in any one of claims 1 to 8, in order to allow a strand of tension thread, known as the extension strand (18, 38), to extend beyond an initial end, and beyond a final end of the seam formed by the stitch (3), wherein, on completion of the sewing:

   the said portion (37) of the tension thread (8) is displaced laterally by a distance which is sufficient to release the tension thread (8) and move it away laterally from a first blade (16) for cutting of the auxiliary threads (4), which is disposed downstream from the means for picking up (5,6,7);

   sewing of the stitch (3) continues for a length such that the tension thread (8) is released laterally relative to the first cutting blade (16) downstream;

   the first cutting blade (16) is actuated in order to cut the auxiliary threads (4) of the stitching (3), and sewing is interrupted by the means for picking up (5,6,7);

   the piece (1) is displaced in the downstream direction, for a length which corresponds to the sum (d1 + d2) of the lengths of the extending strands (18,38) of the tension thread (8), to be formed at the start and at the end of sewing;

   the part of the tension thread (8) to be cut is engaged, in order to separate the extending strand (38) at the end of the piece to be sewn, and the extending strand (18) at the start of a subsequent piece to be sewn, by means of a second cutting blade (17);

   the second cutting blade (17) is actuated; and

   there is replacement to a normal position of the means for picking up (5,6,7), the means (14) for guiding the tension thread, and the said portion (37) of the tension thread, for receipt and sewing of a subsequent piece to be sewn.
10. A method as claimed in claim 9, wherein the said portion (37) of the tension thread (8) is replaced in a normal position before the second cutting blade (17) is actuated.
11. A sewing machine for implementation of a method according to any one of claims 1 to 10, comprising means (5, 6, 7) for picking up at least one stitch (3) formed from auxiliary threads (4) on a piece (1) to be sewn according to a direction of sewing (D), this stitch (3) being of the type which forms a passage (P) which extends in the direction of sewing (D), and means (14, 48, 61) for guiding a thread, known as the tension thread (8), for putting the latter into position in the passage (P) simultaneously with picking up of the auxiliary threads (4), such that this tension thread (8) can slide longitudinally and/or laterally in this passage (P), wherein it comprises means, known as means for release of the tension thread (8), in order to displace transversely relative to the means (5, 6, 7) for picking up, at least one portion (37) of the tension thread, which extends upstream and immediately downstream from the means (5, 6, 7) for picking up, between a normal position for putting into position of the tension thread (8) in the passage (P), and a position for release of the said portion (37) of the tension thread (8), in which the latter is inclined relative to the direction of sewing (D) of the stitch, and passes opposite the means (5, 6, 7) for picking up, beyond the area of action of the means (5, 6, 7) for picking up and beyond the passage (P), in order in particular to permit cutting independently of the auxiliary threads (4) of the stitch (3) and/or of the tension thread (8), by at least the cutting blade (16, 17), which is disposed downstream from the means (5, 6, 7) for picking up and/or formation of loops (62) of the tension thread (8), which are released from the passage (P) whilst sewing is taking place.
12. A machine as claimed in claim 11, wherein the means for release of the tension thread (8) are designed to be able to displace transversely at least the said portion (37) of the tension thread (8), during stitching of the stitch (3) by the means (5, 6, 7) for picking up.
13. A machine as claimed in claims 11 and 12, comprising a motor frame (12) and a work-holder plate (13), which extend globally on one side of the motor frame (12), from means (5, 6, 7) for picking up, wherein the means for release of the tension thread (8) are designed to displace the said portion (37) of the tension thread laterally on the side of the work-holder plate (13), and opposite the motor frame (12), beyond the said passage (P), from the normal position to the position of release.
14. A machine as claimed in any one of claims 11 to 13, wherein the means for release are designed to displace the said portion (37) of the tension thread vertically, by moving it upwards away from the piece (1) to be sewn, beyond the area of action of the means (5, 6, 7) for picking up.
15. A machine as claimed in any one of claims 11 to 14, wherein the means (5, 6, 7) for picking up comprise at least one needle (5), and contain means (9, 10, 11) for movement of the piece to be sewn, wherein the means (9, 10, 11) for movement comprise at least one unit, known as the downstream movement unit (11), which is disposed immediately downstream from the needle (5), and the means for release of the tension thread (8) are designed to displace transversely at least one portion (37) of the tension thread, which extends in the upstream direction, from the downstream movement unit (11).
16. A machine as claimed in any one of claims 1 to 15, wherein the means (14, 48, 61) for guiding the tension thread comprise at least one upstream guiding part (14, 48, 61), which is disposed upstream from the means (5, 6, 7) for picking up, and is supported by support means which are designed to be able to position this guiding part (14, 48, 61) in a normal position in which it guides the tension thread (8), relative to the stitch (3), or in a position for release of the tension thread (8), in which it is displaced transversely relative to the means (5, 6, 7) for picking up, such that these means for support of the upstream guiding part(s) (14, 48, 61) act as means for release of the tension thread (8).
17. A machine as claimed in claim 16, wherein the means for releasing comprise means (45, 68, 72) which are designed to be able to displace transversely at least one guiding part (48, 61) which is distinct from a presser unit.
18. A machine as claimed in one of claims 16 and 17, wherein the means for release of the tension thread comprise at least one double-action actuation unit (23, 45, 68, 72), making it possible to displace the said guiding part (14, 48, 61) transversely between the normal position and the position for release of the tension thread, and vice versa.
19. A machine as claimed in any one of claims 11 to 18, comprising means (14) for guiding the tension thread, formed and/or supported by an upstream presser unit (10) for movement of the piece (1) to be sewn, and means (22, 23, 24) to support the upstream presser unit (10) relative to a frame (12) of the machine, which, in an active position, are designed to apply the upstream presser unit (10) in contact with the piece (1) to be sewn, wherein the means (22, 23, 24) for support are designed to be able to place the upstream presser unit (10) in the position of release of the tension thread (8), in which the upstream presser unit (10) and the means (14) for guiding the tension thread are displaced laterally relative to the means (5, 6, 7) for picking up, such that these means (22, 23, 24) for support of the upstream presser unit (10) act as means for release of the tension thread (8).
20. A machine as claimed in claim 19, wherein the means (22, 23, 24) for support comprise:

    an arm (22) which is articulated by a downstream end, on the frame (12) of the machine, such that it can pivot around a vertical axis (27) and around a transverse horizontal axis (28), and supports the upstream presser unit (10) with the means (14) for guiding the tension thread at its upstream end;

    a double-action actuation unit (23), which is supported by the frame (12), and has an actuation rod (25) which is mobile in translation;

    a rocker arm (24) for connection between the arm (22) and the actuation rod (25);

    and the actuation unit (23) is mounted on the frame (12), such that in a normal position, the actuation rod (25) can exert support pressure on the arm (22) in the direction of application of the upstream presser unit (10), on the piece (1) to be sewn.
21. A machine as claimed in claim 20, wherein the rocker arm (24) for connection has torsion such as, from a movement of translation accompanied by rotation of the actuation rod (25) itself, to give rise to movements of lateral displacement of the upstream presser unit (10), by pivoting the arm (22) around the vertical axis (27), and of vertical displacement of the upstream presser unit (10), by pivoting the arm (22) around the transverse horizontal axis (28).
22. A machine as claimed in one of claims 11 to 21, wherein it comprises a first blade (16) for cutting auxiliary threads (4), which is disposed downstream from the means (5, 6, 7) for picking up, and the said means (22, 23, 24) for release of the tension thread (8) are designed to displace the said portion (37) of the tension thread laterally, from the normal position, by a distance which is sufficient to clear the tension thread (8) laterally from the first blade (16) for cutting the auxiliary threads (4).
23. A machine as claimed in claim 22, wherein it comprises two blades (16, 17) for cutting threads, the first blade (16) being disposed downstream from the means (5, 6, 7) for picking up, in order to cut the auxiliary threads (4) of the oversewing, the second blade (17) being disposed downstream from the first (16), at a distance corresponding to the length (d1) of a strand (18) of tension thread, known as the projecting strand, which is allowed to extend beyond an initial end of the seam formed by the stitch (3), on a subsequent piece to be sewn.
24. A machine as claimed in claims 15 and 23, wherein the first blade (16) is disposed immediately downstream and in the vicinity of the downstream movement unit (11).
25. A machine as claimed in any one of claims 11 to 24, wherein it comprises means (41 to 44) for automatic guiding of the piece (1) to be sewn, relative to the means (14) for guiding, and, if applicable, relative to the cutting blade(s) (16, 17), and means (44) for automatic control of the means for release of the tension thread, and, if applicable, of the cutting blade(s) (16, 17).
26. A machine as claimed in claim 25, wherein the means (41 to 44) for automatic guiding of the piece (1) to be sewn comprise a grasping robot, which is designed and programmed to displace the piece (1) to be sewn on a work-plate (13) of the machine, as the sewing is carried out.
27. A machine as claimed in one of claims 25 and 26, wherein the means (41 to 44) for automatic guiding of the piece (1) to be sewn, and the means (44) for automatic control of the means for release of the tension thread, comprise a programmable numerical system (44), which is designed and programmed, as the sewing takes place, to control the means (5, 6, 7) for picking up, displacements of the piece (1) to be sewn, the means for release of the tension thread (8), and the cutting blade(s) (16, 17).

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