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Title:
DEVICE AND PROCESS OF CONTROL OF THE LENGHT OF NEEDLEFUL IN SEWING MACHINES WITH RUNNING STITCH
Document Type and Number:
WIPO Patent Application WO/2017/187465
Kind Code:
A1
Abstract:
A device of control of the length of needleful in sewing machines (1) with running stitch comprising a series of sensors and/or detecting elements (7), which are placed at a path portion that follows the thread (4) on a mobile portion (8) of the recovery wheel (9) of the thread (4) of the sewing machine (1) and which are configured to detect said thread (4); the sensors and/or detecting elements (7) are also interfaced with a digital signal amplifier, which is in turn connected with a PCB provided with a software program suitable to correlate the presence of the thread (4) at the mobile portion (8) of the recover wheel (9) with an angular measure of rotation of said recovery wheel (9), in order to signal at least one stretch of remaining needleful and/or to suggest the insertion of one or more needlefuls and/or to signal breaks of one or more needlefuls.

Inventors:
PEREGO, Ferruccio (Via Vespri Siciliani 34, Milano, IT)
Application Number:
IT2017/000080
Publication Date:
November 02, 2017
Filing Date:
April 20, 2017
Export Citation:
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Assignee:
COMPLETT AE S.R.L. (Via Caravaggio 2/B, Desio, 20832, IT)
International Classes:
D05B1/04; D05B51/00
Foreign References:
DE102010054104A12011-07-21
JPH09294883A1997-11-18
EP1083255A12001-03-14
EP1223240A22002-07-17
Attorney, Agent or Firm:
IANNONE, Carlo, Luigi et al. (Barzano' & Zanardo Roma S.p.A, Via Piemonte 26, Roma, 00187, IT)
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Claims:
CLAIMS

1. Device of control of the length of needleful in sewing machines (1) with running stitch, wherein said sewing machines have

- at least one needle (3), which is arranged perpendicularly to a support plane, where at least one cloth to be sewed is placed, and vertically operated in translation, with alternating motion, in such a way as it cyclically crosses said cloth, bringing from time to time, above and below the support plane, alternatively, a buttonhole of thread (4) of said needleful for the sewing operation, wherein a first end of at least one needleful of thread (4) is fixed to said cloth to be sewed and a second end is free, and

- at least one wheel (9) of recovery of the thread (4), arranged below the support plane and in a plane substantially parallel to the axis of the needle (3) and composed by a fixed portion (10), where rooms (12, 13) of collection of the recovered thread (4) are present, and by a mobile portion (8), operable with rotary motion with respect to said fixed portion (8) and in synchronized way with the movement of the needle (3), said mobile portion (8) peripherally bringing at least one hook or crochet (11), suitable to clasp said needleful of thread (4) brought below said support plane and to recover a portion of the thread (4) extending from said hook or crochet (11) to said free end of said at least one needleful of thread (4), by passing it within said rooms of collection of the thread (4), due to the rotary motion of said mobile portion (8) of the recovery wheel (9) and the translation motion of the needle (3),

characterized in that said control device comprises a set of sensors and/or detecting elements (7), placed in correspondence of at least one groove (5) which is provided transversally and according to a prefixed angle with respect to the circumference of said mobile portion (8) of said wheel (9), said sensors and/or detecting elements (7) being configured to detect said thread (4) and being interfaced to at least one digital signal amplifier which is in turn connected with a PCB provided with a software program, suitable to correlate the presence of the thread (4) at said groove (5) with an angular rotation measure of said mobile portion (8) of said wheel (9), in order to signal at least one stretch of remaining needleful and/or suggest the insertion of one or more needlefuls and/or signal breaks of one or more needlefuls.

2. Control device as claimed in claim 1 , characterized in that said sensor and/or detecting elements (7) include optical fibres readers or sensors and/or transmitting and/or receiving photocells for the detection of the thread (4), through at least one reading ray.

3. Control device as claimed in claim 1 , characterized in that, during the rotation of said wheel (9), said sensors and/or detecting elements (7) detect the profile of the circumference of said mobile portion (8) of the wheel (9) and are configured to perform three different reading conditions (A, B, C), which are constituted, respectively, by the presence of said mobile portion (8) of the wheel (9), the presence of said groove (5) on said mobile portion (8) without the thread (4) and the presence of said groove (5) on said mobile portion (8) with the thread (4).

4. Control device as claimed in claim 3, characterized in that said sensor and/or detecting elements (7) have three different calibrations and have LEDs for signalling the presence of said groove (5) with or without the thread (4),

5. Control device as claimed in claim 1 , characterized in that said software program is configured to stop said sewing machine (1) in prefixed stop positions with a prefixed length of said thread (4).

6. Process for the control of the length of needleful in sewing machines with running stitch which can be implemented by means of a control device according to claim 1 , characterized in that a detection of the thread (4), by said sensor and/or detecting elements (7), at certain times of every cycle of construction of each sewing point made by said sewing machine on said cloth under processing, automatically causes the stop of said sewing machines in at least one prefixed position of said at least one needleful of thread (4), so that between said prefixed position and the free end of said at least one needleful of thread (4) at least a first predetermined measure of length of thread (4) is provided.

7. Control process as claimed in claim 6, characterized in that said sewing machine is stopped when said at least one needleful presents, between said stop positions of the machine and said free end of the needleful, at least one second predetermined measure of length of thread (4), in order to perform a join operation between two or more needlefuls.

8. Control process as claimed in claim 6, characterized in that said sewing machine is stopped when the needle (3) is outside the cloth being sewed and allows to perform a join operation between two or more needlefuls by loading said needle (3) with a further needleful, said sewing machine (1) operating again in order to perform, for a given stretch (12), an overlap between at least two needlefuls for a random number of stitches.

9. Control process as claimed in claim 6, characterized in that, when said sewing machine (1) stops, said thread (4) of a first needleful is discharged from the needle (3), said cloth being sewed is released from the needle (3), said needle (3) is positioned again at the end of at least one point previously made, a second needleful is loaded onto the needle (3) and said sewing machine (1) still sews with said second needleful (2) which overlaps said first needleful for a number of points pre-selectable by the operator.

Description:
DEVICE AND PROCESS OF CONTROL OF THE LENGHT OF NEEDLEFUL IN SEWING MACHINES WITH RUNNING STITCH

The present invention generically concerns a device and relative process of control of the length of needleful in programmable sewing machines, specifically suitable to make seams with so-called running stitch, which is generally used, as ornamental purpose, in manufactured clothes, particularly in the rim of the lapels of jackets, coats, skirts, as well as in the manufacturing of trousers, handbags, gloves and similar items.

More specifically, the invention relates to a device and related process suitable to determine, during sewing, how much thread of the needleful remains, so as to adjust a tensioning group to get a more constant sewing throughout the needleful and/or give rise to the look at will thereof.

As a result, it is also possible to determine when the needleful is ending and stop the sewing machine, getting also a warning of thread breakage, in order to allow the insertion of a new needleful and thus lighten operator's activity.

Notoriously, the running stitch is made by a single thread of fixed length (called needleful), crossing the flaps of the fabric along its entire length, so as to place alternately on the right and on the back of the cloth to be sewn, so as the sewing stitches, variable and adjustable in length, are alternatively visible on one and the other side of the fabric subjected to sewing.

The traditional sewing machines, performing running stitch sewing, such as those ones described, for example, in the prior art patent documents EP1233094A2 and EP 233095A2, use substantially a vertical axis needle, arranged perpendicularly to a support plane, where the cloth to be sewn is placed.

The needle can be actuated with reciprocating motion along its axis, so that cyclically passes through the cloth to be sewn, leading, from time to time, a buttonhole of thread of the needleful used for sewing, alternately above and below the support plane.

An upper end of the needleful of thread is stapled on the cloth under sewing, while the other end is left free and also, below the support plane, a recovery wheel of the thread is provided, arranged in a plane substantially parallel to the axis of the needle, which is composed of a fixed part, having a circular development, and a revolving part which can be operated with rotary motion and synchronized with the needle movement, compared to the fixed part.

In the fixed part of the wheel a warehouse for the collection of the recovered thread is present, while the revolving part leads peripherally a lower hook or crochet, which, following the rotation of the wheel and movement of the needle, hooks the buttonhole of thread led below the support plane and recovers the portion of thread extending from the lower crochet to the free end of the needleful, passing it into the collection warehouse.

Another upper hook or crochet, positioned above the support plane, is designed to hook the buttonhole of thread led by the needle above the support plane and hold it, while the thread is loaded into the warehouse of the recovery wheel.

A main drawback of the sewing machines with running stitch of the known type is the need to establish a predefine thread needleful, of which it is not possible to determine the remaining amount during sewing.

This causes particular operator's attention or ability, who must stop the machine before the needleful ends, in order to insert a new one.

Indeed, the operation of sewing with a running stitch is usually composed of more than one needleful and it is therefore necessary to join more needlefuls and this should be done before the end of the needleful under processing.

Currently, however, the identification of this moment (i.e. shortly before the end of the needleful) is entrusted, as said, to operator's experience, who can exploit two options: seeing the thread when it is on the upper crochet or, given cloths repeatability, indicatively yet knowing in which point of the cloth under working the needleful ends.

However, as already previously mentioned, these two methods present some obvious problems, the main one of which consists in the fact that the operator must be absolutely an expert in the field and/or always relatively diligent to the condition of the needleful.

For example, if the operator fails to realize that the needleful is ended (especially when talking about colour sewing) will continue to sew and will be forced to take in the final stitches, with a clear waste of time.

Even, if this happens in a leather cloth, great attention must be put also to take in the holes of the not sewn stitches, because, otherwise, the cloth under working could be discarded.

This currently happens, although, during sewing, the needleful breaks and, even in this case, the identification of the break is entrusted to the operator.

It must be also highlighted the fact that the break of the needleful may also be due to the insertion, by the operator, of a length too long or in any case wrong of the needleful itself.

With the aim to overcome these drawbacks, some users use a point- counter so as to determine when the needleful is coming at the end.

However, it is an empirical system which can be applied only if the cloth to be sewn is repeatable by type of material and stitch length.

Finally, from the point of view of the sewing, it is always less tensioned as the needleful is consumed, unless the operator does not continue to act on the tensioning group.

Within the abovementioned requirements, a purpose of the present invention is to overcome the drawbacks just cited and, in particular, to create a device of control of the length of needleful in sewing machines with running stitch, which allows the operator to avoid to provide part of his attention to the visual control of the length of needleful remained during the sewing operation, in order to use even less skilled operators, with a time and quality saving.

Other purpose of the present invention is to provide an extremely safe and reliable device of control of the length of needleful in sewing machines with running stitch, which permits to precisely identify when the needleful is almost at its end, so as to allow the operator to join with a subsequent needleful or perform the operation of fixing the needleful yet during sewing, thus getting a substantial time and quality saving.

Another purpose of the invention is to provide a device of control of the length of needleful in sewing machines with running stitch, enabling the identification of a possible break of the needleful.

A further purpose of the invention is to indicate a process of control of the length of needleful in sewing machines with running stitch which can be implemented through the device of control referred above.

A last but not least purpose of the invention is to provide a device of control of the length of needleful in sewing machines with running stitch, which has an essentially simple constructive structure and can be produced at relatively low costs, compared to the achieved advantages.

These and other purposes are achieved by a device of control of the length of needleful in sewing machines with running stitch, according to the attached claim 1 , and a relative process of control, according to the attached claim 6.

Other detail features of the device and process of control in question are described in the subsequent the claims.

In advantageous way, the control device, object of the invention, is basically composed of an array of optical fibres which are inserted into the mobile portion of the wheel of the sewing machine, where the thread runs during the construction of the upper stitch.

The device includes a dedicated hardware and software, suitable to operate with the cycles of the sewing machine in question.

Moreover, the device according to the invention can be interfaced with the upper and lower tensioning systems of the needleful, in order to get a more homogeneous sewing, compared to what can be obtained with sewing machines with running stitch of traditional type.

Finally, the device allows to locate the break of the thread and, thus, functions as sensor of thread break.

Further purposes and advantages of the present invention will become more evident from the description that follows, relating to a preferred and illustrative, but not limiting, embodiment of the device of control of the length of needleful in sewing machines with a running stitch and the relative process, according to the present invention, and from the attached drawings, where:

- figure 1 shows a lateral view of a sewing machine with running stitch, which uses the control device according to the invention; - figure 2 shows a front view of the sewing machine with running stitch of figure 1 , according to the present invention;

- figure 3 shows an exploded perspective view of the sewing machine with running stitch of figure 1 , according to the present invention;

- figure 4 shows an enlargement of a portion of the sewing machine with running stitch of figure 3, according to the present invention;

- figures 5, 6 and 7 show a series of reading steps performed by the control device of the length of needleful, according to the present invention.

In the sewing machines with a traditional running stitch, the needleful has a length determined by the operator and the needle of the sewing machine stops sewing on the cloth under processing at a breakpoint when a situation of "uncontrolled end needleful" occurs, i.e. when the thread of the needleful still presents a prefixed measure (which is not sewn).

Normally, however, in a cloth under working (to be sewn) there is not only one needleful, but a continuous sequence of needlefuls, that is a "long needleful" (about 80-90 cm) consisting of many needlefuls and, in such a case, there are various problems, such as those ones of manufacturing in a qualitatively correct manner (i.e. respecting the geometry of the stitch) said "long needleful" and getting that the two or more needlefuls are connected each other in order to prevent their destruction.

For example, a join method between two needlefuls provides for a situation of "controlled end needleful", where the prefixed length of the thread from the breakpoint is always longer than said prefixed measure (about 8-9 cm, for which the machine does not sew anymore).

Said prefixed length is currently decided by the operator, who, therefore, must rely on his own ability and which obliges him/her to pay great attention, because it must always check the total needleful length to be loaded and also have a reference point of the cloth under working at which approximately the needleful is ending or continuously control the thread passing through the upper crochet.

This results further problematic, taking into account that the consumption of the needleful, besides being influenced by the length of the stitch, also depends greatly on the thickness of the material of the cloth to be sewn. On the contrary, the control device according to the invention, overcoming the drawbacks mentioned, directly indicates to the operator that the end of the thread of the needleful is close to the prefixed length and, therefore, before such a length is reached, stops the sewing machine, allowing to perform one method of joining two needlefuls.

Furthermore, the device allows to detect any break of the thread and, therefore, also works as a sensor of break of the thread.

In case of joining the needlefuls according to the above mentioned method, the control device according to the invention identifies the prefixed measure of the needleful of thread and stops the sewing machine when the needle is elevated and ready to be loaded with a new needleful by the operator, who can then restarts to sew by overlapping for a stretch the two needlefuls for a random number of stitches.

In case the needlefuls are joined according to other methods, the control device, object of the invention, operates similarly, but, in this case, when the sewing machine stops, the operator will discharge the thread of the needleful from the needle, free the fabric of the cloth from the pressing foot of the needle, reposition the needle at the end of one of the stitches previously made, load the second needleful and start again sewing with the latter, which overcomes the first needleful, for a number of stitches that is chosen by the operator itself.

With reference to the above mentioned figures, the device of control according to the invention is made using sensors or optical fibres readers and/or photocells, of the transmitter/receiver type, generally indicated with 7 in the attached figure 4, which are positioned along the path of the thread 4 of the sewing machine 1 and which, in particular, are applied inside the mobile portion 8 of the wheel 9, the latter suitable to the recovery of the thread 4 and arranged in a plane substantially parallel to the axis of the needle 3.

The wheel 9 substantially comprises a fixed portion 10 and the mobile portion 8, which can be operated with rotary motion around its axis, with respect to the fixed portion 10, synchronized with the movement of the needle 3.

In particular, the mobile portion 8 of the wheel 9 peripherally leads a rotary hook or crochet 11 , placed below the support plane of the sewing machine 1 , which can be engaged with the buttonhole of thread 4 cyclically led by the needle 3 below the support plane, in order to operate the recovery of the stretch of needleful of thread extending from the needle 3 up to the free end of the needleful and its loading inside the rooms of collection of the fixed portion 10 of the wheel 9; in particular, the rooms for collecting the recovered thread 4 include respective tracks, which are separated by a relief and communicating each other, so as to allow the thread 4, inserted into the inlet due to the rotation of the rotary hook or crochet 11 , to pass from one track to another at every cycle of composition of the sewing stitch.

According to the invention, a groove 5 having a defined angular position is performed on the mobile portion 8 of the wheel 9, in order to maintain a right synchronization with the optical fibers readers or photocells 7 which are able to detect the thread 4; said readers or photocells 7 are interfaced with a digital signal amplifier which, in turn, is connected with a control PCB provided with a proper software program.

Since inside the mobile portion 8 of the wheel 9 the thread 4 runs in a cyclic and alternating manner, integrating the electronics of the device of control according to the invention with the applicative software of the PCB, which also allows to manage the "master" and "slave" motors of the sewing machine 1 , it is possible to put in a biunique relationship the presence of the thread 4 inside the groove 5 of the mobile portion 8 of the wheel 9 with the degrees of rotation of said mobile portion 8.

In fact, the realization of said groove 5 allows to identify, during the rotation of the wheel 9 and therefore of the mobile portion 8, three different reading conditions performed by said photocells 7:

1) filled mobile portion 8 of the wheel 9 and "filled reading" (condition shown with A in the enclosed figure 5);

2) groove 5 without the thread 4 and "void reading" (condition shown with B in the enclosed figure 6);

3) groove 5 with the thread 4 and "thread reading", which is a "void reading" with the detection of the thread 4 (condition shown with C in the enclosed figure 7).

The detection is possible by means of a proper placement of one or more optical fiber readers or photocells 7, so as to detect the profile of the external circumference of the mobile portion 8.

For that purpose, the optical fiber reader 7 has three different calibrations and has two LEDs, which turn on according to the following modes:

- in case of detection of the groove 5 and "void reading" (condition

B) , one first LED is on;

- in case of detection of the groove 5 and "thread reading" (condition

C) , one second LED is on;

- in case of "filled reading" (condition A), no LEDs are on.

In this way, the identification of the thread 4 at the groove 5 of the mobile portion 8 of the wheel 9 (corresponding to the stitches made by the sewing machine 1 above and below the fabric of the cloth under working) allows the control device, through the dedicated software program, to stop the machine in the stopping positions corresponding to a prefixed length of thread 4.

In particular, the dedicated applicative software, on the basis of the data collected and following a proper processing the latter, allows to signal the stretch of remaining needleful, suggest the insertion of a new needleful and signal the break of the needleful.

Moreover, if two or more grooves 5 are provided on the mobile portion 8 of the wheel 9, it is possible to obtain other functions, such as the determination of an amount of remaining thread of the needleful and the signal of a length of needleful longer than a maximum allowed value, as well as it is possible to change the positions of the "slave" motors of the sewing machine 1 that modify the tensioning of the needleful and possibly the stitch length and/or to activate a fixing function (forward and backward) and/or to get a determination of the needleful to be inserted (currently entrusted to operator's experience).

It has been in practice observed that the device of control of the length of needleful in sewing machines with running stitch, according to the present invention, fully complies with the set task, since it is able to offer absolute operation flexibility, avoiding the need for the operator to stop sewing before the needleful ends (and possibly near the end of the needleful) and to have to put a new predefined needleful of thread, the remaining amount of which is not possible to know during sewing, automatically determining when the needleful is ending and stopping at that time the sewing machine, in order to allow the operator the insertion of a new needleful and also get an alarm of thread break.

The characteristics of the device of control of the length of needleful, which is the object of the present invention, as well the resulting advantages, are clear from the description just given.

It is finally clear that many other variations may be made to the control device in question, without departing from the principle of novelty intrinsic in the inventive idea expressed in the appended claims, as it is clear that, in the practical implementation of the invention, materials, shapes and sizes of the illustrated details can be changed, as needed, and replaced with others technically equivalent.