EP0041435A1 - Thread chain severing device for overseam sewing machine - Google Patents

Abstract

The chain thread produced by the overseam sewing machine forms alternately a seam (37) for each assembled article (36a, 36b) and a free strand (38) connecting the assembled articles (36a, 36b) two by two. The device comprises an electrical heating filament (6) arranged in the vicinity of the path (7) of the chain thread (37, 38) and a tube (12) connected to a suction means in order to draw the free strands (38) towards the heating filament (6) in succession, so as to cut these free strands successively by fusion at a point (39) located in proximity to the seam of the adjacent article. The heating filament (6) is mounted next to the mouth (16) of the tube (12) connected to the suction means. The invention is used to allow the overseam sewing machine to stop between each batch of articles. <IMAGE>

Description

The present invention relates to a cutting device for serger or similar machine, and in particular to cut the chain of textile threads produced continuously at the outlet of such a machine, the chain alternately constituting a seam for each assembled article and a free cord connecting assembled articles, this device comprising an electric heating filament disposed in the vicinity of the path of the chain, and a barrel connected to suction means for successively attracting the free cords to the heating filament, so as to successively cut these free cords by fusion at a point located near the seam of the neighboring article.

It is known that an overlock generally produces continuously a cord of textile threads - called a chain - which carries out an edge-to-edge stitching on the articles to be assembled which are presented in an appropriate manner at the entry of this overlock.

Overlockers are in particular, but not limited to, used for making articles of clothing such as sweaters or socks. In this last example, after having produced a textile tube for each sock, the tubes are made to run parallel to each other so that their end is closed by a seam produced by means of the serger.

Thus, between two articles assembled successively by the serger, the chain, produced continuously by the serger, constitutes a free cord which connects these two articles.

The object of the invention is to cut each free cord at its two ends so as to separate the assembled articles without undesirable pieces of chain remaining attached to these articles.

According to US Pat. Nos. 3,142,279, 3,159,124, 3,304,897, and 3,217,680, the heating filament is mounted transversely in this mouth.

It has been found according to the invention that this known arrangement has many drawbacks. Indeed, the filament is exposed directly to the suction air stream. To be kept at the temperature necessary to cut the chain, the filament must therefore be electrically supplied at a relatively high intensity, involving a significant energy expenditure, and an installation supporting the planned intensities.

The temperature of the filament may fluctuate depending on the speed and temperature of the air drawn into the barrel. These parameters must therefore be kept constant, which is an additional constraint.

On the other hand, if the suction is interrupted in the known devices, it is necessary to immediately cut off the supply of the electric filament. Otherwise, it would melt almost instantaneously, because the electric current flowing through it would be much too strong if the heat was not partially removed in the air stream.

On the other hand, if we have taken the precaution to stop the feeding of the filament at the same time as the suction, during the restarting, the filament takes a long time to recover its temperature in the air stream. It is of course not possible to restart the suction means until a certain time after having closed the filament supply circuit, but there is then the risk of delaying a little too long in starting the suction, which would destroy the filament by fusion.

Following all this, it will be understood that the user of an installation of the known type will prefer never to interrupt the aspiration or the feeding of the filament, and that these installations are moreover made to operate in this way. ie continuously. This continuous operation is the source of noise in the workshops, and also of energy consumption during certain periods when this is not necessary. Indeed, overlockers of the kind more particularly targeted by the invention are machines operating very quickly, which can for example perform a series of seams in 5 seconds after which they can be stopped for about twenty seconds until the next batch of items is dispatched.

The object of the invention is to remedy these drawbacks by providing a device making it possible to proceed without stopping and restarting, at a rapid rate, the overlock machine, so as to limit the energy consumption and the noise production to what is strictly necessary.

It should be noted in this connection that the energy consumption of the suction means is not negligible, and the savings achievable by stopping the device as soon as possible are serious.

According to the invention, the cutting device is characterized in that the heating filament is mounted next to the mouth of the barrel connected to the suction means.

Thus, the heating filament is little influenced by the air flow. It is therefore satisfied with a reduced supply power and does not risk instantaneously melting in the event of the aspiration being stopped. When the device is started up, the filament heats up quickly because it is not subjected to intense cooling by the air from the suction air stream. It is therefore without inconvenience to stop and restart the device repeatedly.

Other features and advantages of the invention will emerge from the description below.

• . la figure 1 est une vue en perspective du dispositif conforme à l'invention;
• . la figure 2 est une vue de dessus du dispositif de la figure 1;
• . la figure 3 est une vue en coupe selon la ligne III-III de la figure 2;
• . les figures 4 à 6 sont des vues partielles en coupe montrant le fonctionnement du dispositif monté à la sortie d'une surjeteuse; et
• . la figure 7 est une vue du schéma électrique simplifié d'une surjeteuse munie du dispositif des figures 1 à 6.

In the appended drawings, given by way of nonlimiting examples:

• . Figure 1 is a perspective view of the device according to the invention;
• . Figure 2 is a top view of the device of Figure 1;
• . Figure 3 is a sectional view along line III-III of Figure 2;
• . Figures 4 to 6 are partial sectional views showing the operation of the device mounted at the outlet of a serger; and
• . FIG. 7 is a view of the simplified electrical diagram of an overlock machine provided with the device of FIGS. 1 to 6.

The device shown in Figures 1 to 3 comprises a housing 1 to which is welded a bent tab 2 intended to be screwed to the serger. The housing 1 comprises a tube 3 of square section and axis substantially parallel to the direction of travel of the articles to be assembled in the serger at the point where the chain is formed. The tube 3 is closed at its two ends by two plates 4 made of an electrically insulating material.

The device further comprises an electric heating filament 6 mounted in the vicinity of the path 7 (Figure 2) that follow the seams made using the chain. In addition, the active central part of the filament 6 is substantially vertical in the service position and perpendicular to the path 7. The heating filament 6 is connected to the electrical supply wires 8 by two rigid wires 9 parallel to the axis of the tube 3 and slidably engaged in the plates 4. Two locking studs 11 screwed into the tube 3 in line with each of the rigid wires 9 block these relative to the housing 1. The supply wires 8 are connected to means shown in the Figure 7, and which will be described later, allowing the heating of the filament 6 to be adjusted according to three different powers.

A suction barrel 12, with an axis parallel to the rigid wires 9, is also mounted to slide through the two insulating plates 4. A screw 13 engaged in the upper wall of the tube 3, blocks the barrel 12 in translation relative to the housing 1. The central part of the heating filament 6 is connected to the rigid wires 9 by two horizontal parts 14 biased towards the barrel 12, so that the central part of the filament 6 is located very close to the outer wall of the barrel 12, without touching it.

From its mouth 16, the barrel 12 has a longitudinal slot 17 which extends substantially to the right of the heating filament 6 and along the generatrix of the barrel ₁ 2, the closest to the filament 6. The slot 17 is widened on the side of the mouth 16.

A metal compressed air supply tube 18 is welded along the barrel 12, between its mouth 16 and the housing 1. On the side of the mouth 16, which is flared truncally, the tube 18 is connected to a thin conduit 19 which is bent in a hairpin to bypass the mouth 16 and sink a certain distance inside the barrel 12, beyond the start 17a of the slot 17. The conduit 19 is pressed against the inner wall of the barrel 12, according to a generator of the latter angularly spaced about 120 ° relative to the slot 17. Opposite the mouth 16, the tube 18, which is bent to pass next to the box 1, is terminated by a connector 21 allowing its connection to a compressed air distribution circuit. The connector 21 is welded to the barrel 12 by means of a tubular support 22, opposite the mouth 16 relative to the housing 1. The wall of the end of the barrel 12 adjacent to the connector 21 is thickened, and a bent pipe 23 is fitted therein with its outlet 24 directed downwards.

In FIGS. 4 to 6, the device is mounted on the frame 31 of an overlock machine which comprises blades 32 intended to refresh the edges of the articles 36a, 36b to be assembled, and needles 33 which produce the chain 34. When two edges superimposed of an article to be assembled 36a or 36b are engaged between the needles 33, the chain 34 forms a seam 37 connecting these two edges. On the other hand, the chain 34 produced when no article to be assembled is engaged between the needles 34, constitutes a free cord 38 which, before being cut, connects the two seams 37 of two different assembled articles 36a, 36b (FIG. 4 ).

As shown in Figures 2 and 4 to 6, the edges to be assembled of articles 36a, 36b are constrained by means forming part of the serger, follow the path 7 which, in 7a, is initially parallel to the axis of the barrel 12, and close enough to this axis to be directed towards the interior of the barrel 12.

The seams 37 then follow a curved part 7b of the path 7 so as to pass a short distance past the filament 6 while avoiding the barrel 12.

Figure 7 shows the electrical installation of the installation. The serger 51 is supplied from a voltage source 52 via a general contactor 53. Downstream of the latter, and in parallel with the serger 51 is connected a solenoid valve 54 mounted on the tube 56 of compressed air supply intended to be connected to conduit 19 (Figures 1 to 3). The solenoid valve 54 is of the closed type in the absence of electrical voltage.

A transformer 57 has its input terminals A and B - connected just downstream of the general contactor 53. The filament 6 is connected to the output of the transformer 57, between a terminal 58 of 0 Volt voltage and a terminal 59 which can be connected alternately to one of three transformer outputs 61,62,63, delivering respectively 1.3 V (standby voltage), 1.5 V, and 1.7 V (working voltages). A switch 64 makes it possible to choose the working voltage. A relay contactor 66 alternately puts the terminal 59 of the filament 6 under working voltage (1.5 or 1.7 V) or under standby voltage.

The transformer 57 has two other output terminals 67 between which it delivers a control voltage of 24 V.

Between these terminals 67 are connected in parallel the coil 68 of the contactor 66, the coil 69 of a contactor 71 controlling the electrical supply of the solenoid valve 54, a timer contact 72, and the coil 73 of a contactor 74 controlling the overlock 51 supply independently of the solenoid valve 54. In series with the coil 73 is a switch 76 actuable by a feeler 77 sensitive to the passage of articles being assembled in the serger.

The probe 77 controls the opening of the switch 76 and of the contact 72 in the absence of articles and their closing in the opposite case. However, the timer ensures a slight delay each time contact 72 is opened.

A contactor 78 enables the filament 6 to be put out of service.

We will now describe the operation of the device described above.

The contactor 53 being closed, and in the absence of articles to be assembled, the contacts 71,72,74, and 76 are open so that the serger 51 is stopped, and the solenoid valve 54 is closed, eliminating the consumption of compressed air for suction in the barrel 12. The terminal 59 of the filament 6 is connected to the terminal 61 of the transformer 57 (standby voltage 1.3 V). This is the situation shown in Figure 7.

As soon as articles to be assembled arrive at the serger 51, the probe 77 commands the immediate closure of the contacts 72 and 76. The contactor 74 closes and the serger starts.

The closure of the contact 72 in turn causes the closure of the contactor 71 as well as the tilting of the contactor 66. Thus, the suction begins in the barrel 12, and the filament 6 is supplied under one of its two working voltages selected using switch 64.

When the series of articles leaves the serger 51, the probe 77 controls the stopping of the serger. It also controls, but with delay thanks to the timer, the opening of the contact 71 and the switching of the contactor 66. Because of this delay, the cutting of the chain of the last articles of the series can be carried out although all the articles have already left the serger 51 and it is already stopped.

The passage of the filament 6 from the working power to the standby power makes it possible to maintain the filament at a substantially constant temperature, that the suction means whether in service or not.

In the example shown in Figures 4 to 6, the items to be assembled are socks 36a, 36b. The seam 37 of the assembled sock 36a runs along the path 7 in front of the filament 6, without being affected by the heating of the latter, the distance from the path 7 to the filament 6 being sufficient in this regard. On the other hand, transfer means provided on the serger force the seams 37 to follow the path 7 without deviating despite the aspiration into the barrel 12.

The free cord 38, which connects the end of the seam 37 of the already sewn sock 36a, at the start of the seam 37 of the sock being sewn 36b, curves with respect to the path 7, and engages in the slot 17 of the barrel 12, under the effect of the suction in the latter. Thus, as soon as the sewn sock 36a has completely exceeded the filament 6, a point 39 of the adjacent end of the free cord 38 meets the heating filament 6, which cuts the cord at this point 39.

As shown in FIG. 5, under the effect of the suction in the barrel 12, the free cord 38 which is no longer attached only to the sock 36b, engages in the barrel 12 while avoiding the filament 6. Thus, (FIG. 6), when the start of the seam 37 of the second sock 36b engages in front of the filament 6, the other end of the free cord 38 in turn engages in the slot 17 and comes into contact with the filament 6, at another point 39, so as to be sectioned. An additional advance of the sock 36b along the path 7 brings back to the situation in FIG. 4. Furthermore, as can be seen in this figure, the cord 38 cut at its two ends is sucked by the barrel 12 and passes through the pipe bent 23 to be ejected through the outlet 24 of the latter.

The position of the barrel and the filament 6 can be adjusted according to a relatively large stroke relative to the housing 1 and to the bent tab 2, so that the device according to the invention can be very easily adapted to different models of sergers. On the other hand, the studs 11 allow to carry out a fine adjustment of the position of the filament 6 relative to the start 17a of the slot 17, so that the cut of each free cord is ensured and that the piece of free cord remaining on each assembled article is as small as possible.

As we have seen, the invention makes it possible to produce a device for cutting free chain cords, which is particularly inexpensive to manufacture and maintain. In addition, this device contributes to the robustness of the seams produced since the heating filament welds the strands at the end of each seam 37.

Of course, the invention is not limited to the examples shown, and numerous modifications can be made to these examples without departing from the scope of the invention.

This is how the means of attraction could be different, and include for example a vacuum pump system. These means could also include a fan, which sucks the free cords towards the filament, or on the contrary pushes them in this direction by blowing.

Furthermore, the housing 1 can be modified, and the adjustment of the position of the filament 6 could be made dependent on that of the barrel 12.

Claims (8)

1. Cutting device for serger or similar machine, and in particular for cutting the chain of textile threads produced continuously at the outlet of such a machine, the chain alternately constituting a seam (37) for each article (36a, 36b) assembled and a free cord (38) connecting the assembled articles (36a, 36b), this device comprising an electric heating filament (6) disposed in the vicinity of the path (7) of the chain (37,38) and a connected barrel (12) to suction means (18,19) for successively attracting the free cords (38) towards the heating filament (6), so as to successively cut these free cords by fusion at a point (39) located near the seam of the neighboring article, characterized in that the heating filament (6) is mounted next to the mouth (16) of the barrel (12) connected to the suction means (18,19). 2. Device according to claim 1, characterized in that the barrel (12) has a longitudinal slot (17) starting from its mouth (16) and intended to receive and guide the chain towards the heating filament (6) and that this heating filament (6) is mounted substantially at the start (17a) of the slot (17). 3. Device according to one of claims 1 or 2, characterized in that it comprises means (11) for adjusting the distance separating the filament (6) from the end of the barrel (12). 4. Device according to claim 3, characterized in that these means comprise two electrically insulating parallel plates (4) traversed by the barrel (12) and fixed in a tube (3), and two wires (9) supplying the filament (6), rigid and parallel to the barrel (12), mounted to slide in the plates (4) and associated with locking studs (11) engaged in the tube (3). 5. Device according to any one of claims 1 to 4, characterized in that it comprises means (61,62, 66) for feeding the filament (6) according to at least two powers different heating means, and means for automatically passing the filament (6) to its lowest heating power when the suction means (18,19) are out of operation, and for bringing the filament (6) towards the other heating power when the suction means are put into service (18,19). 6. Device according to claim 5, characterized in that it comprises means (71) for stopping and restarting the suction means (18,19,56) depending respectively on stops and restarting of the serger (51). 7. Device according to claim 6, characterized in that the starting and stopping of the serger (51) is controlled from a probe (77) sensitive to the presence of articles to be assembled on the serger . 8. Device according to claim 7, characterized in that it comprises a timer (72) for delaying the stopping of the suction means (56,18,19) relative to the stopping of the serger (51) .

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