Title:
BROKEN THREADS DETECTING DEVICE IN EMBROIDERY MACHINES
United States Patent 3850122


Abstract:
Device for detecting the breaking of a thread, particularly on an embroidery machine with automatic change of the color and/or ratio, of the type having for each needle an oscillating lever, bearing a first electric contact and being movable in respect of a second fixed electric contact, said lever being kept in position of open contact due to the stretching of the corresponding thread, and automatically moving to a position of closed contact upon ceasing of said stretching due to the breaking of the thread, comprising disconnecting means, to bring simultaneously out of operation all the oscillating levers bearing electric contacts, at the start of each color and/or ratio changing step on the machine, and connecting means to bring straight after back into operation only the contact-bearing levers corresponding to the needles starting to work, said connecting means operating in response to the tensioning of the threads of said needles starting to work.



Inventors:
DAELI D
Application Number:
05/337745
Publication Date:
11/26/1974
Filing Date:
03/02/1973
Assignee:
METALMECCANICA SPA,IT
Primary Class:
Other Classes:
28/187, 28/194, 66/163, 200/61.18
International Classes:
D05C11/14; (IPC1-7): D05B69/36; B65H63/02
Field of Search:
112/218R,219R,79R,221 28
View Patent Images:
US Patent References:
3714916N/A1973-02-06Saray
3025807Tufting apparatus1962-03-20Gebert
3009433Automatic stop device for multineedle sewing machines1961-11-21Kuhn
2594168Electrical stop motion for knitting machines1952-04-22Heyne



Foreign References:
GB1079637A
Primary Examiner:
Hunter, Hampton H.
Attorney, Agent or Firm:
Stevens, Davis, Miller & Mosher
Claims:
I claim

1. A device for detecting the breaking of a thread, particularly on an embroidery machine with automatic color and ratio change

2. The device according to claim 1, in which the fixed contact consists of a metal bar mounted substantially parallel to the needle axis, and said lever, is formed like a wire frame, said lever being oscillatable around a pivot which is parallel to said bar forming the fixed contact.

3. The device as in claim 1, in which said disconnecting means comprise at least a slide, a sliding transversally to the needles axes and bearing said pivots of the oscillating contact-bearing levers, said slide being movable between a working position in which the contact-bearing levers may rest against said fixed contacts, and a non-working position in which said levers cannot contact said fixed contacts.

4. The device as in claim 1, further comprising an oscillating metal stirrup, forming said connecting means for the contact-bearing lever and an electrical feeding line, means movable mounting said stirrup between a lowered working position, in which it forms an electrical connection between said electrical feeding line and said contact-bearing lever, and a raised non-working position, in which it breaks said electrical connection.

5. The device as in claim 4, in which to said oscillating stirrup are associated spring means, arranged so as to act on the stirrup itself, on one side and respectively on the other side of a dead center position, so as to force said stirrup towards said working position or respectively towards said non-working position.

6. The device as in claim 4, in which said electrical feeding line is formed by a rigid metal rod, running transversally to the needles axes, a portion of said stirups extending over said metal rod, said rod being movable upwardly, at the start of each color and/or ratio changing step on the machine, in order to push and cause the simultaneous oscillation of all the stirrups from the lowered working position to the raised non-working position, the only stirrups corresponding to the needles at work, being brought back to the working position so as to operate the corresponding contact-bearing levers, said return to the working position being obtained in response to the tensioning of the threads carried by said needles at work.

Description:
BACKGROUND OF THE INVENTION

The object of the present invention is a device for detecting broken threads, particularly studied for embroidery machines provided with an automatic color and/or ratio change.

As known, there are at present, being applied on embroidery machines of the traditional type, signaling devices adapted to operate in the event of breaking of a needle or shuttle thread. On the whole, such devices are based on the fact that the needle thread, when engaging the shuttle thread during forming of the stitch, remains forcedly stretched.

If, therefore, the needle thread is let through the usually curl-shaped end of an oscillating lever, said thread, while being stretched, keeps the lever itself raised in respect of an appropriately positioned longitudinal metal bar. When the thread breaks -- or loosens due to the breaking of the shuttle thread -- said oscillating lever drops onto said metal bar.

The above lever, in cooperation with said longitudinal metal bar, may hence behave like a switch for closing an electric circuit ending into an optical or acoustical signaling device or into a relay for stopping the machine from working.

Of course, the current is supplied to said electric circuit, through appropriate means, only for the length of time during which the thread, according to the working cycle, has to be stretched.

If, during said length of time -- due to the breaking or loosening of the thread -- the lever remains in contact with the metal bar, as said above, the signaling and/or stopping circuit is operated, thus allowing the operator to easily find the broken thread and provide for its re-connection

Nonetheless, in more recent embroidery machines, such broken threads detecting devices can no longer be used, owing to the different working cycle of the machines themselves. In the latter, in fact, not all the needles are generally at work, whereby the corresponding threads stay loose, also during the stitch-forming stage.

More precisely, the above machines are conceived in such a way as to alternatively operate different sets of needles, according to the color of the thread engaged thereby, and obviously, to the chromatic result one wishes to obtain.

In view thereof, some needles are cyclically moved backward, through appropriate mechanisms operated by the Jacquard device, and hence, they do not work, i.e., they do not engage the relative shuttle. A known detecting device could obviously not distinguish between the loosening of a thread, due to breaking, and the loosening of a thread due to the non-working of the corresponding needle.

Likewise, it is not possible to use -- on an embroidery machine with automatic color and/or ratio change -- a detecting device, itself already known per se, operating in dependence of the movement of the shuttle and, in particular, of the fall-back speed of the shuttle, which speed turns out to be equal both in the event of thread breaking and in the event of non-working of the corresponding needle.

SUMMARY OF THE INVENTION

The detecting device according to the present invention, is instead conceived and made in such a way as to operate only on those threads which have to be stretched, according to the working cycle. In a device for detecting the breaking of a thread, particularly of an embroidery machine with automatic change of the color and/or ratio, of the type having for each needle an oscillating lever, bearing a first electric contact and being movable in respect of a second fixed electric contact, said lever being kept in position of open contact due to the stretching of the corresponding thread and automatically moving to a position of closed contact upon ceasing of said stretching due to the breaking of the thread, the above specified result is obtained due to the fact that said detecting device comprises disconnecting means, to bring simultaneously out of operation all the oscillating levers bearing electric contacts, at the start of each color and/or ratio changing step on the machine, and connecting means to bring straight after back into operation only the contact-bearing levers corresponding to the needles starting to work, said connecting means operating in response to the tensioning of the threads of said needles starting to work.

More precisely, for each needle of the machine, the fixed contact consists of a metal bar mounted substantially parallel to the needle axis, and the movable contact, associated to the oscillating lever, consists of the lever itself, formed like a wire frame, said lever being mounted oscillating around a pivot which is parallel to said bar forming the fixed contact.

According to a first embodiment, said disconnecting means comprise at least a slide, sliding transversally to the needles axes and bearing one or more of said pivots of the oscillating contact-bearing levers, said slide being movable between a working position in which the contact-bearing levers may rest against said fixed contacts, and a disconnected position in which said levers are moved away from the said fixed contacts. Said contact-bearing levers act at the same time as operating means, in that they are formed like leaf springs, each lever being adapted to take, on one hand, a relieved, non-working position, in which the respective end finds itself above and spaced from said fixed contact, and, on the other hand, each lever being kept in a working position, with the respective end placed below said fixed contact, under the pressure exerted on the lever itself, against its elastic reaction, by the corresponding stretched thread.

According to a different embodiment, the detecting device of the invention further comprises an oscillating metal stirrup, forming said connecting means for the contact-bearing lever, said stirrup being mounted movable between a lowered, working position, in which it forms an electric connection between an electric feeding line and said contact-bearing lever, and a raised non-Zworking position, in which it breaks said electric connection.

Preferably, said electric feeding line is formed by a rigid metal rod, running transversally to the needles axes, said rod being movable upward, at the start of each color and/or ratio changing step on the machine, in order to push and cause the simultaneous oscillation of all the stirrups from the lowered working position to the raised non-working position, the only stirrups corresponding to the needles at work, being brought back to the working position so as to operate the corresponding contact-bearing levers, said return to the working position being obtained in response to the stretching of the threads carried by said needles at work.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other functional and structural characteristics of the broken threads detecting device for embroidery machines with automatic color and/or ratio change, forming the object of the present invention, will be better understood from the following description, with reference to the accompanying drawing, in which:

FIG. 1 shows the longitudinal section of a set of detecting devices adapted to be applied to a corresponding set of needles in an embroidery machine;

FIG. 2 shows a cross section of a detecting device according to the invention;

FIG. 3 is a prospective view of a short section of detecting devices;

FIGS. 4 and 5 are longitudinal section views of a short length of detecting devices, according to a second embodiment, respectively in a connected and disconnected position;

FIG. 6 is a prospective view of a short length of detecting devices according to said second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With particular reference to the embodiment of the FIGS. 1 to 3 of the accompanying drawing, the detecting device according to the invention comprises an elongated box-like body 1, made of suitable insulating material, preferably plastic. The body 1 is mounted on the embroidery machine with its longitudinal axis perpendicular to the needles axes.

The opposed walls of said box-like body are each provided with a plurality of slits 2, having a curvilinear shape and spaced at regular intervals one from the other; the slits are arranged in such a way that, to each slit in a wall corresponds a slit in the opposite wall, in an alignment parallel to the needles axes.

In the upper portion of the lobes, which are hence formed in the two opposite walls of the box-like body 1, are mounted, transversally to the body 1, the bars 3, preferably of cyclindrical section, made of electrically conductive material.

Into the bottom of the same box-like body 1 is formed a longitudinal slot 4, along which may slide a slide 5, which is in turn made of insulating material, for example plastic.

Said slide 5 is provided with two lateral walls 6 between which are arranged the cylindrical bars 7, in a number equal to that of the bars 3. On the upper surface of the slide 5 is further fixed a metal band 8.

On the bars 7 are wound the terminal portions 9 of a flexible elastic wire substantially formed as a frame 10, which represents the oscillating contact-bearing lever cited further above. The ends 11 of the terminal portions of said frames 10 bear against the metal band 8 and hence make the terminal portions themselves capable of supporting the elastic reaction of the frame or lever 10, when the latter is caused to oscillate downward.

The slide 5 is connected, at one end, with the movable core 12 of an electromagnet 13, while on the other end 14 of the slide is hooked a contrast spring 15.

The movement of the said slide 5 takes place in such a way as to cause the shifting of the pivots 7 of levers 10, so that the latter may move away from the contact bars 3.

Said contact bars 3 are electrically interconnected by means of the continuous cable 16, ending into a signaling and/or stopping circuit.

As specified above, the electric current is supplied to the electric circuit, formed by elements 8, 11, 10, 3, 16, through appropriate means known per se, only during that part of the operating cycle of the machine in which all the working threads must be stretched for the forming of the stitches.

The electromagnet 13 is instead operated by a second circuit 17, controlled by the Jacquard device, according to the color change and, hence, according to the needles engaged in the forming of the embroidery stitches.

During operation, the detecting device according to the invention may assume the two following different positions:

a. In correspondence of a working thread 18: the end of the oscillating lever 10 finds itself below the contact bar 3; in the event of broken or loose thread 19, the lever 10 elastically oscillates upward up to contacting the bar 3, thus closing the signaling circuit.

b. In correspondence of a non-working thread 20: the end of the oscillating lever 10 is placed above the contact bar 3; the lever 10 is hence no longer controlled by the thread, and the corresponding signaling device is out-of-work.

The passage of the oscillating levers above or below the relative contact bars 3, is controlled by the electromagnet 13 which, at each color and/or ratio changing step, shifts the slide 5 towards the right (in respect of FIG. 1). In this position, the levers 10 are away from the bars 3 and -- being all the threads loose -- they can oscillate upward.

Then, the needles× selection is carried out in a manner known per se, the needles having to form the embroidery stitches are moved to the working position, and the corresponding threads are stretched.

Under the pressure exerted by the stretched threads, only the levers 10 corresponding to said threads are forced downward. At this moment, the electromagnet 13 is de-energized and the spring 15, thus released, calls back the slide 5 towards the left (in respect of FIG. 1). All the levers 10 being under pressure of the stretched threads, thus shift below the bars 3, while all the other levers 10 (corresponding to the non-working threads), hold a raised position above the bars 3.

Also in the embodiment of FIGS. 4 to 6, the detecting device according to the invention is formed of a box-like body 1, made of insulating material, preferably plastic.

The corresponding side walls of the body 1 are provided with substantially rectilinear slits 2', having a suitable inclination in respect of the vertical.

Transversally to said walls are arranged three bars for each pair of opposed slits 2': the bar 3 is placed on one side of a slit 2', while the bar 7 and a further bar 25 are placed on the opposite side.

All the bars 3 are supplied with electric current through the cable 16, as said above, only at the moment of forming of the embroidery stitches, namely when the working threads are stretched.

On the bar 7 are wound the terminal portions 9 of a wire frame forming the oscillating lever 10, the ends 11' of which extend by a suitable length, up to bearing against the stops 20.

The free end of the said lever 10 extends beyond and below the bar 3; it should be noted here that a first difference between this embodiment and the embodiment shown in FIGS. 1 to 3 lies in the fact that the bars 7 are fixed and that, therefore, the levers 10 are always positioned below the bars 3. Also in this case, as in the embodiment of FIGS. 1 to 3, the elastic reaction of the lever 10 tends to force the lever 10 itself against the bar 3.

An M-shaped wire element or stirrup 22 is further pivoted on the side walls of the body 1, said stirrup 22 being provided with two lateral arms 23, which are arranged parallel and externally to the walls themselves.

To the M-shaped central portion 24 of said stirrup 22, is hooked an end of the spring 26, tee other end of which is fixed to the transversal bar 25.

The stirrup 22 can oscillate around its pivoting points on the side walls of the body 1, between a lowered active position and a raised inactive position, passing through an intermediate dead center position represented by the position in which the bar 25, the pivoting point of the stirrup 22, and the hooking point of the spring 26 on the stirrup 22, are in alignment. On one side and respectively on the other side of the dead center position, the action of the spring 26 forces the stirrup 22 to hold its active, or respectively inactive position.

In its lowered active position, the central portion of each stirrup 22 bears on the stop 21, being formed by a block fixed substantially in the middle of the base of body 1.

In the same active position the lower ends (FIG. 4) of the arms 23 of the stirrup 22 are in contact with the rod 27, which acts at the same time as electric line for the signaling and/or stopping electric circuit.

Moreover, the upper portions (FIG. 3) of the arms 23 of the stirrup 22 are in contact with the ends 11' of the oscillating lever 10, hence assuring electric continuity between the lever 10 itself and the same stirrup 22.

The upward oscillation of the stirrup 22 is obtained through the upward movement of the longitudinal rod 27, which pushes the ends of all the arms 23 and then returns to its lowered position of rest.

The arms 23, together with the stirrup 22, then move to their raised inactive position, in which the electric contact between the ends of arms 23 and the rod 27 is broken.

The movement of the rod 27 is controlled by a pair of electromagnets (not shown in the drawing), which are energized by the Jacquard control device.

It is now extremely easy to understand the operation of the detecting device according to the invention.

At the start of each color and/or ratio changing step in the embroidery machine, the arms 23 of the stirrup 22 are pushed upward by means of the rod 27, as specified above.

At the start the first beating up, only the threads 18 of a selected group, engaged in the forming of the stitch, are stretched and hence exert a pressure on the corresponding levers 10 and stirrups 22. The stirrups 22, corresponding to the selected group of threads, are hence lowered and establish the electric contact with the rod 27 and the levers 10.

The levers 10 are therefore apt to act as switches for closing the signaling and/or stopping circuit, in the event of breaking or irregular loosening of the threads 18; in this case, in fact, the levers 10 are free to elastically oscillate upward thus closing the electric contact with the bar 3.

The upward oscillation movement of all of the stirrups 22 and the subsequent downward movement of the stirrups 22, correspoding to the selected group of threads, are then cyclically performed at each color and/or ratio changing step in the embroidery machine.

It is anyhow understood that there may be several embodiments other than those described above, without thereby departing from the scope of the present invention.