Seam blocking system for sewing machines

Abstract

This is a seam blocking system for sewing machines. More specifically, it is a system that allows the sewing of a garment to be blocked without inconveniencing the operator.

Description

[0001] SEAM BLOCKING SYSTEM FOR SEWING MACHINES

[0002] Specification

[0003] The present invention relates generally to a seam blocking system for sewing machines. More particularly, it is a system for blocking the stitching of a garment without inconveniencing the operator.

[0004] As is well known, in the production of certain portions of garments, it is necessary to stop sewing beforehand. This is the case with the sewing of the so- called 'waistband' in trousers, i.e. the upper portion of the trousers to which the actual waistband can be attached.

[0005] This portion of the trousers should not be totally sewn to the lower part, so that the outermost flap can be turned inwards and sewn on later with another sewing machine.

[0006] In order to block the seam at the desired time, the known technique currently has three operating modes.

[0007] The first mode is mechanical. This means that the looper is prevented from completing the stitch by preventing the thread carried by the needle from entering the loop created by the looper underneath. To be exact, the loop is widened by means of pegs in the sewing operation to facilitate the passage of the thread through the loop.

[0008] In order to prevent the loop from widening and to prevent the stitch from being completed, there is a small plate, appropriately shaped, which prevents the pegs from opening the loop.

[0009] This plate must, however, be replaced depending on the needle spacing being worked, as the distance between the pegs can vary depending on the needle spacing. In addition, the replacement of such a peg is rather challenging, as it is placed in a rather inaccessible position to reach.

[0010] A second way to lock the seam is electrically, i.e. by blocking the movement of the sewing needles.

[0011] While this mode prevents the needles from penetrating the fabric, it is still necessary to free the partially sewn fabric by cutting the sewing threads at the bottom of the sewing area. A small knife is fixed under the needle plate for this purpose.

[0012] This method of clamping is also inconvenient as the needles, remaining stationary, do not make it easier to move the fabric portions.

[0013] In fact, these are sewing machines in which the transport jaws are absent and the movement of the fabric during sewing is achieved by means of an auxiliary conveyor coupled to a roller in the lower part and thanks to the transversal translatory movement of the needles themselves.

[0014] A third method of realisation to stop the stitching involves the positioning of a small tube in the area where the stitching is completed. This tube blows air at the moment when the seam needs to be blocked, so as to move the loop and prevent the stitch from being completed.

[0015] This mode, however, is not accurate, as the stitching may start later than desired, and thus the length of the seam is not constant. Furthermore, with such a mode, one does not have full control of the thread, and therefore, it may sometimes still allow a stitch to be completed.

[0016] It is an object of the present invention to provide a seam blocking system for sewing machines which is convenient for the operator to use.

[0017] Another purpose of the invention is to provide a seam blocking system that does not force adjustments to be made depending on the type and width of the stitch being performed.

[0018] A further purpose of the invention is to provide a seam blocking system that keeps the sewing needles moving, so that the fabric can still be moved, regardless of whether or not the seam is being sewn.

[0019] These and other purposes are achieved, according to the invention, by a seam blocking system for a sewing machine, comprising a support and a derailleur having at least one peg, the derailleur being capable of translating with respect to the same support according to a first direction.

[0020] In particular, the blocking system is characterised by the fact that means of movement are included which are capable of moving the derailleur according to a rotation or a second direction not coinciding with the previously defined first direction.

[0021] Thanks to the action of such means of movement, it is possible to allow a regular shifting of the derailleur according to the first direction, i.e. analogous to the known technique.

[0022] But at the same time, the means of movement allow a shifting of the derailleur such that the one or more pegs on the derailleur are in a position that does not contribute to the regular completion of the stitching.

[0023] Advantageously, the blocking system according to the invention may comprise a first shaft to which the derailleur is attached, said first shaft being capable of translating according to the first direction and allowing the one or more pegs to follow the movement of the respective stitching needles. But at the same time said first shaft may be rotating, so as to move the same one or more pegs from the area of cooperation with the respective sewing needles. In this way, when the first shaft is rotated, it is possible to stop the sewing but at the same time the sewing machine remains in motion, with the sewing needles still allowing the fabric to be moved due to their rototranslational movement.

[0024] In addition, an annular body coupled with means of displacement can be attached to the first shaft, so that when the means of displacement are actuated, the first shaft rotates.

[0025] Advantageously, the annular body may comprise a toothed portion coupled to a movable rack, so that upon a movement of the rack there corresponds a rotation of the annular body and the first shaft, and, consequently, of the derailleur.

[0026] In addition, the toothed portion may have a width less than the width of the rack, so that it can translate with respect to the rack and remain coupled and meshed with it.

[0027] Advantageously, the rack can be attached to a stem of a pneumatic cylinder by means of which the first shaft and thus the derailleur can rotate.

[0028] In addition, the first shaft can be coupled to a second shaft so that it can rotate with respect to the second shaft and translate together with the second shaft. In particular, the first shaft and the second shaft are coupled to each other by means of an internal threaded grub screw.

[0029] In this way, while the second shaft can only translate, according to the known technique, the first shaft, in addition to being able to translate following the movement of the first shaft, can also rotate so as to move the derailleur and its pins.

[0030] In order to provide the translatory movement, the second shaft can be attached to a fork, which can be coupled to the known mechanisms of the sewing machine.

[0031] Advantageously, translation means of the derailleur, capable of translating the derailleur according to a first direction and a second direction, different from the first direction, so as to bring the one or more pegs on the derailleur out of the area of cooperation with the respective sewing needles, can be included.

[0032] In this way, sewing is obstructed and prevented, while still keeping the sewing machine moving.

[0033] Further features and details can be better understood from the following description, which is given as a non-limiting example, as well as from the accompanying drawing tables in which figures 1 and 2 are axonometric views from above and below, respectively, of a seam blocking system, according to the invention, of a sewing machine; figure 3 is a frontal view of the sewing machine with the seam blocking system arranged in a first position so as to allow the sewing stitch to be made; figure 4 is a front view of the sewing machine with the seam blocking system arranged in a second position such that the sewing stitch cannot be realised.

[0034] With reference to the appended figures, a sewing lock system for a sewing machine is referred to 10 as a whole.

[0035] The blocking system 10 comprises a derailleur 12 movable relative to a support 14 fixed to the sewing machine.

[0036] The derailleur 12 comprises:

[0037] - a bar 16 to which pegs 18 are attached (for cleanliness of the boards, a single peg is shown);

[0038] - a first roto-translating shaft 20 to which the bar 16 is attached;

[0039] - a second translating shaft 22, connected to the first shaft 20 so as to translate it axially, leaving it free to rotate; and

[0040] - a fork 24 to which the second shaft 22 is fixed.

[0041] In particular, the fork 24 is connected to the other mechanisms of a sewing machine sewing head and is capable of axially translating the second shaft 22.

[0042] In this way, the pegs 18 also translate together with the rod 16, which is connected to the first shaft 20.

[0043] In fact, the first shaft 20 and the second shaft 22 are fixed to each other by means of an internal threaded grub screw.

[0044] As shown in figure 3, the pegs 18, in their forward and backward movement, widen the loop made by the thread carried on top by a needle A, so as to facilitate the insertion of the thread moved by a swinging hook C.

[0045] An annular body 26 with a toothed portion 28 is also attached to the first shaft 20, which engages the teeth of a rack 30 translating in the support 14.

[0046] The rack 30 is constrained to a rod 32 of a pneumatic cylinder 34.

[0047] When the pneumatic cylinder 34 is actuated, the rod 32 causes the rack 30 to translate, which, in turn, causes the annular body 26 to rotate and, consequently, also the first roto-translating shaft 20.

[0048] As can be seen from Figures 1 and 2, the rack 30 has a width greater than the thickness of the annular body 26, so that it still allows the roto-translating movement of the first shaft 20, regardless of the angular position of the first shaft 20 itself.

[0049] When it is necessary to lock the stitching, i.e. prevent the sewing stitches from being sewn, the blocking system 10 provides that the pegs 18 do not cooperate with the needle A and the looper C, as shown in figure 4, so as not to widen the sewing loop and make it almost impossible to insert the thread in the loop itself.

[0050] In particular, for this purpose, the pneumatic cylinder 34 is actuated, the rod 32 causes the rack 30 to translate which, in turn, causes the annular body 26 to rotate and, consequently, also the first rotating shaft 20 to rotate.

[0051] The rod 16 also rotates a few degrees, also moving the rungs 18 to the position shown in figure 4.

[0052] In this position, the pegs 18 no longer cooperate with the needle A and the loop is therefore not widened.

[0053] The blocking system 10 according to the invention thus makes it possible to prevent the stitches from being sewn by simply operating the pneumatic cylinder 34, while still keeping the machine in motion, without ever stopping.

[0054] There is no need for the insertion or replacement of any plate, as provided by the known technique according to the mechanical mode.

[0055] Furthermore, as the sewing machine is still in motion, the rototranslation of one or more needles is still permitted, thus allowing the fabric to be moved even when sewing is not taking place.

[0056] Variants are provided which are to be considered included in the scope of protection of the present invention. For example, the number of pegs may be different from that illustrated in the appended figures.

[0057] Furthermore, the bar 16, instead of rotating, may translate laterally, so as to bring the pegs 18 to an area which is in any case not affected by the action of the needle A.

Claims

CLAIMS1 . Seam blocking system (10) for a sewing machine, comprising:- a support (14)- a derailleur (12) with at least one pin (18); said derailleur (12) capable of moving with respect to the support (14) in a direction X, characterised by the fact that means of movement (20, 26, 28, 30, 32, 34) suitable for moving the derailleur (12) according to a rotation or a direction Y are included, the direction Y not being coincident with the direction X.

2. Blocking system (10) according to the preceding claim, comprising a first shaft (20) to which the derailleur (12) is fixed, the first shaft (20) being capable of translating according to the direction X, the first shaft (20) being rotating.

3. Blocking system (10) according to the preceding claim, wherein an annular body (26) coupled to displacement means (30, 32, 34) is fixed to the first shaft (20), so that upon an actuation of the displacement means (30, 32, 34), the first shaft (20) rotates.

4. Blocking system (10) according to the preceding claim, wherein the annular body (26) comprises a toothed portion (28) coupled to a movable rack (30).

5. Blocking system (10) according to the preceding claim, wherein the toothed portion (28) has a width less than the width of the rack.

6. Blocking system (10) according to the preceding claim, wherein the rack (30) is attached to a rod (32) of a pneumatic cylinder (34).

7. Blocking system (10) according to any one of the preceding claims, wherein the first shaft (20) is coupled to a second shaft (22) so as to be able to rotate with respect to the second shaft (22) and to translate together with the second shaft8. Blocking system (10) according to the preceding claim, wherein the first shaft (20) and the second shaft (22) are coupled to each other by means of an internal threaded grub screw.

9. Blocking system (10) according to claim 6 or 7, wherein the second shaft(22) is fixed to a fork (24).

10. Blocking system according to claim 1 , wherein the derailleur translation means are included, suitable for translating the derailleur according to a direction Y, the direction Y being different from the direction X.

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