US3782313A

US3782313A - Device for synchronizing the slackening of the needle thread with the threadcutting, with timing of the slackening of the needle thread and independent control of the delay of disc opening for lockstitch sewing machines

Info

Publication number: US3782313A
Application number: US00308297A
Authority: US
Inventors: C Conti
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-11-24
Filing date: 1972-11-20
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: DE2257169A1; IT941262B; CH556423A; JPS4876644A; NL7215801A; ES408928A1

Abstract

An electropneumatic device is disclosed for synchronizing the thread slackening mechanism of a lock stitch sewing machine with the cutting of the thread, said device being capable of controlling the delay in the opening of the thread tensioning discs independently of the stroke of the piston which actuates the thread cutter. In its simplest embodiment, the device comprises, in addition to a pneumatic thread cutting device and a pneumatic device for controlling the tension of the needle thread and a source of compressed air, two valve means, the first of which is connected to the thread cutting mechanism and to a flow restrictor, the second valve means being connected to the thread tension control mechanism and to a storage reservoir for compressed air.

Description

Ilnited States Patent Conti 1 ,Ian. I, 11974 DEVICE FOR SYNCI-IRONIZING THE 3,443,540 5/1969 Hannemann et a1 112/252 SLACKENHNG OF E NEEDLE THREAD 3,528,379 9/1970 Miller 1 12/254 X 3,667,410 6/1972 Bianchi ll2/219 B WITH THE THREADCIJTTING, WITH TIMING OF THE SLACKENING OF THE NEEDLE TIIREAD AND INDEPENDENT CONTROL OF THE DELAY OF DISC OPENING FOR LOCKSTITCII SEWING MACHINES [76] Inventor: Cesare L. Conti, Via Varese 18,

Milan, Italy [22] Filed: Nov. 20, 1972 [2]] Appl. No.: 308,297

[30] Foreign Application Priority Data Nov. 24, 1971 Italy 31523 A/71 [52] 1U.S. C1. 1112/252, 112/254 [51] Int. Cl D05b 65/02 [58] Field ofSearch 112/219 R,219 A,

[56] References Cited UNlTED STATES PATENTS 3,298,341 1/1967 Bonis 112/219 B Primary ExaminerWerner H. Schroeder Att0rney--Frank .1. Jordan [57] ABSTRACT An electropneumatic device is disclosed for synchronizing the thread slackening mechanism of a lock stitch sewing machine with the cutting of the thread, said device being capable of controlling the delay in the opening of the thread tensioning discs independently of the stroke of the piston which actuates the thread cutter. In its simplest embodiment, the device comprises, in addition to a pneumatic thread cutting device and a pneumatic device for controlling the tension of the needle thread and a source of compressed air, two valve means, the first of which is connected to the thread cutting mechanism and to a flow restrictor, the second valve means being connected to the thread tension control mechanism and to a storage reservoir for compressed air.

3 Claims, 7 Drawing Figures 1* 10.00.100.03 u I -'I o o" 31."- 0000. alu e...

DEVICE FOR SYNCI'IIRONIZING THE SLACKENING OF THE NEEDLE THREAD WITH THE THREADCIJTTING, WITH TIMING OF THE SLACIIENING OE THE NEEDLE THREAD AND INDEPENDENT CONTROL OF THE DELAY OE DISC OPENING EOE IJOCKSTITCH SEWING MACHINES BACKGROUND OF THE INVENTION This invention relates to a device for synchronizing the slackening of the tension of the needle thread and the cutting, with timing of the slackening of the thread tension and independent control of the disc opening, particularly for lockstitch sewing machines.

PRIOR ART In the US. Pat. No. 3,635,180 of Jan. 18, 1972 there had been disclosed and claimed a device for synchronizing the slackening of the thread tension and cutting with timing of the slackening of the tension of the thread for lockstitch sewing machines. This device essentially comprised a thread cutting device which was pneumatically actuated and had an air feed, a device for controlling the thread tension, also pneumatically actuated and having an air feed, a source of compressed air, a magnetically actuated control valve connected to said thread cutting device and also to said tension control device and having a first position for connecting said source to the intake side of said thread cutting device and a second position for interconnecting the intake side of said thread cutting device for the intake side of said thread tension control device, so that a pressure applied to said cutting device in said first position of said valve is discharged from said thread cutting device for actuating said thread tension control device in said second position of said valve.

Although the operation of the device as disclosed in the aforementioned patent is as reliable as desired and is fully satisfactory, it has proven desirable, in practice to have at hand a device of the kind referred to above, in which the control of the delay in the opening of the disc might take place in a manner which is independent of the (active) return stroke of the actuation piston of the thread cutting mechanism.

OBJECTS OF THE INVENTION The principal object of the present invention is thus to provide a device for synchronizing the slackening of the needle thread tension and the cutting, which not only is equipped with means for timing the slackening of the tension of said thread, but also with means which are adapted to cause the control of the delay in the opening of the disc to be carried out independently of the (active) return stroke of the cutting device actuating piston.

Another object of the present invention is to provide a synchronizing device of the kind referred to above, which is capable of affording a greater accuracy in the regulation of the delay time, thus providing not only a pneumatic delay device connected to the thread cutting control piston, but also an additional pneumatic delay device connected to the actuating piston of the needle thread cutting mechanism.

SUMMARY OF THE INVENTION In its broader aspect, the present invention thus relates to a device for synchronizing the slackening of the tension of the needle thread and the cutting, in a sewing machine, characterized in that it essentially comprises:

a pneumatic thread cutting mechanism, having a compressed air intake;

a pneumatic control device for the tension of the thread, having an air input and an air output, the latter being terminated by a flow regulator;

a source of compressed air;

a storage reservoir for compressed air;

a first control valve means, magnetically actuated and connected to said thread cutting device as well as to a rate of flow regulator;

a second control valve means, magnetically actuated and connected to said thread tension control device as well as to said compressed air storage reservoir;

said first magnetically controlled valve means having a first position for connecting said compressed air source to the air input of said thread cutting device, and a second position for connecting the air input of said thread cutting device to the rate of flow regulator belonging to said first valve means;

said magnetically controlled second valve means having a first position for connecting said compressed air source to said compressed air storage reservoir, and a second position for connecting said compressed air storage reservoir to the air input of said thread tension control device, and

means for positioning, alternatingly and simultaneously, said first and said second magnetically actuated valve means, into said first or said second positions.

The foregoing and other objects, features and advantages of the present invention will be better understood from the ensuing description of a few exemplary embodiments, which do not involve any limitation, and which are shown in the accompanying drawings.

DRAWINGS FIG. l is an operative diagram of the simplest embodiment of the invention, as shown in the at rest configuration and in that subsequent to thread cutting;

FIG. 2 is a diagram, similar to that of FIG. ll, and shows the position in readiness for the active return stroke intended for cutting the thread;

FIG. 3 is an alternative embodiment of the structure shown in FIG. ll, and in a position which exactly corresponds to that of FIG. I, that is, the at rest position;

FIG. 4 shows the embodiment of FIG. 3 in the position in readiness for the active return, thread cutting, stroke, a position which is similar to that viewed in FIG. 2.

FIG. 5 shows a further embodiment of the invention, in the at rest position and in the position subsequent to the thread cutting operation.

FIG. 6 shows the embodiment of FIG. 5 in the position in readiness for the active return, thread cutting stroke, and

FIG. 7 is a diagrammatic overall view which shows in a simplified manner the arrangement of the several component parts of the pneumatic system, to show the functional connections in a sewing machine, the latter having also been merely diagrammatically shown, along with the electric synchronizing device for the needle-positioning motor (the latter having been shown as a symbol).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Inasmuch as the general operation of a conventional pneumatic device for actuating the thread cutter and the cutting devices connected therewith is generally known, this will no longer particularly be described as such: on the other hand, having reference to the US. Pat. No. 3,635,180 recalled above, it will be seen in that patent a detailed description of such a device.

It is important to recall, conversely, prior to passing to a detailed description of the several embodiments of the present invention, that the basic difference between the present invention and the one disclosed and claimed in the US. Pat. No. 3,635,180 lies in that the above mentioned patent had, as its basic feature, the pneumatic interconnection between the air input of the thread cutting device and the air input of the thread control device. In the present invention, on the contrary, such a constructional and functional mutual dependency cannot be found, inasmuch as the thread cutting device and the tension control device are never pneumatically interconnected with one another. As a matter of fact, the provision of an air storage reservoir and of an additional rate of flow regulator has just the object of rendering the two devices synchronized with one another, but independent of one another from a functional standpoint. The result is that the device according to the present invention affords a sensitivity and an adjustability range which are incomparably wider than those afforded by the invention the subject of the above mentioned'US. Patent.

Having now particular reference to FIG. 1, there will be seen the main component parts of the device, namely: a source of compressed air, I, in the form of a pipe section, a first three-way electromagnetic valve, having two positions, 2, the piping 4 which connects the electromagnetic valve 2 with the cutter control piston 3 (an bee seen, diagrammatically shown, at 1 l, with the counterblade 12, also diagrammatically depicted), a second electromagnetic valve, 2A, having likewise three ways and two positions, an air storage reservoir, R, a piping 4A connecting the reservoir R with the valve 2A, a piping 6 which connects the electromagnetic valve 2A with the needle thread tension slackening control piston 5. There can also be seen, diagrammatically shown, the piston stem 8 having a point which is adapted to penetrate between the

discs

9 and 10 of the thread presser. The diagram of FIG. 1 also shows, in a diagrammatical fashion, at 13, that the piston 3 has one degree of freedom: it should be enabled to oscillate about an axis perpendicular to the sheet of the drawing to follow the motion of the cutter without jamming. It can also be seen that one of the ways of the electromagnetic valve 2 is terminated by a flow regulator (restrictor) 7 which is the pneumatic equivalent of a delay device. Another flow regulator, 7A, terminates a piping, 6A, which discharges the air from the piston 5 for slackening the thread tension. An electric main, T, is also shown, which is intended synchronously to control the two two-position

electromagnetic valves

2 and 2A. The electromagnetic valve 2A receives compressed air from the source 1 through the pipe branch 1A.

By examining now the diagrams of FIG. 1 and FIG. 2 conjointly, it can be readily seen what follows.

As compressed air enters the electromagnetic valve 2, it reaches the piston 3 via the piping 4 and shifts the cutter 11 towards the right, as viewed on the drawing. Simultaneously, the electromagnetic valve 2A feeds compressed air, via the

pipes

1A and 4A, to the storage reservoir R to fill it up. Meanwhile, the thread tension slackening piston 5 is discharging the air that it has received through the pipe 6, into the pipe 6A and therefrom into the atmosphere via the flow regulator 7A. This configuration, which is clearly shown in FIG. 2, is the intermediate position, that is to say the one in which the cutter 1 1 has been shifted to the right end of its stroke prior to starting the thread cutting stage.

In orser that the operational cycle may be thoroughly understood, it suffices to recall the three steps, namely:

1. Starting position of FIG. 1: the cutter is at the extreme left.

2. Intermediate position of FIG. 2: the cutter is at the extreme right, and

3. Position of FIG. 1 again: the cutter is at the extreme left once more and has reached its starting position again.

Summing up, it has been seen that the position of FIG. 2 can be defined also as a charge position: as a matter of fact, both the thread cutting control piston 3 and the storage reservoir R are charged with air. Thus, the two electromagnetic valves are in what has been defined hereinbefore as the first position.

As the

electromagnetic valves

2 and 2A switch to the second position, one obtains the configuration of FIG. 1, that is: The air intakes 1 and 1A are closed, the piston 3 (biassed by a spring, which can be seen in the drawings, in a mabber which is exactly akin to that of the piston 5, also equipped with a recoil spring) discharges air through the pipe 4 and the flow regulator 7, and the reservoir R charges the piston by pushing it towards the right and, in the meanwhile, the flow regulator 7A, connected with the cylinder which contains the piston 5 through the piping 6A, tenders an additional regulation possibility for the discharge.

By observing the FIGS. 1 and 2 conjointly, it can be noticed that, in practice, the flow regulator (restrictor) 7A, is always in operation: in practice, it is a two-fold pneumatic delay device since it is active both in delaying the charging and the discharging of the cylinder which houses the piston 5. This possibility is an important and advantageous feature of the invention, and it should be observed, at the outset, that a similar possibility exists, only for the discharge of the piston 3 by the agency of the flow regulator 7A and this independently of the possibility of regulating both the charging and the discharge of the piston 5. It can now be understood how the device according to the present invention affords an extremely wide regulation range since not only the charging and discharging speeds of cylinders which house the pistons which control the cutting of the thread and the tension of the thread can be regulated independently, but this can be done, moreover, with an extremely high accuracy so as to fulfil, in practice, even the severest processing requirements.

To summarize now what has been said in connection with FIGS. 1 and 2, the operation of the device described above takes place as follows:

I. Feeding compressed air to the cutter control piston 3 (FIG. 2) and, simultaneously, charging the storage reservoir R: the cutter 11 is shifted towards the right and is prepared to grasp the thread.

2. The return spring of the piston 5 shifts the piston towards the left and discharges it: air is discharged through the flow regulation device 7A and it is thus possible to adjust the speed at which the discs 9 and It) are brought close to one another.

3. The thread has been cut (FIG. ll) and the

electromagnetic valves

2 and 2A have meanwhile been brought to their second position. The piston of the cylinder, 3, is discharged through the pipe 4, the electromagnetic valve 2 (which is open), and the flow regulator 7. By so doing, the cutting speed of the cutter 111 can be adjusted in a manner which is totally independent of the regulation of the opening and closing of the discs 9 and 110, as outlined above. Meanwhile, also the electromagnetic valve 2A has been switched to its second position (FIG. It) and the air under pressure held in the reservoir R flows, after having passed through the electromagnetic valve 2A (second position), into the cylinder of the piston 5 pushing the same towards the left against the bias of the specially provided spring (shown, though unreferenced, in the drawing) and thus the stem 3 can, with its pointed end, open the discs of the thread tension regulating device: at this stage it is important to observe that the mode of operation (opening speed and time) of the discs can be adjusted in an independent manner since the cylinder which houses the piston 5 is also connected to the pipe 6A, which is terminated by the flow regulating device (restrictor) 7A. Thus, by properly calibrating the device 7A any desired mode of regulation of the opening speed of the

discs

3 and 10 can be obtained. In the reverse mode, on account of the characteristic arrangement of the

pipes

6 and 6A, of the cylinder of the piston 5 and of the flow regulator 7A, also the closing (approaching) speed of the discs 9 and MD can be adjusted as desired.

Once again, it should be observed that no direct pneumatic connection ever exists between the piston 3 and the piston S.

The alternative embodiment depicted in FIGS. 3 and 4! is very similar to the embodiment described immediately above in connection with FIGS. 1 and 2, a single detail excepted. The piston 3, in the embodiment of FIGS. 3 and 4, is no longer spring biassed, but is a double acting piston. The electromagnetic valve 2 provides a further pathway which opens into the piping 1B and the latter is situated, on the cylinder of the piston 3, in a position which is opposite to the one at which the pipe 4 is installed. Thus, in the intermediate position of FIG. 4 the pressure which charges the cylinder of the piston 3 acts, rather than against a spring bias, against the pressure obtaining in the portion of the cylinder which is at the right of the piston 3, so that the air contained in the right portion of the cylinder of 3, is discharged since the electromagnetic valve 2, in its first position, establishes a communication, inter alia, between the right chamber of the cylinder of 3 with the atmosphere (FlG. 4). in the configuration of FIG. 3, on the contrary, the leftward bias of the spring against the piston 3 is replaced by the pressure of the air which arrives through the electromagnetic valve and the pipe TB, into the right chamber of the cylinder of 3. The air contained in the left chamber of the cylinder of 3 is discharged in a regulated manner in this meanwhile, through the piping 4, the electromagnetic valve 2 in its second position, and the flow regulator (restrictor) 7. In the remainder, the operation is the exact counterpart of that of the embodiment of FIGS. l and 2, so that a detailed description of the operation thereof need not be repeated. It will be noticed, in this connection, that all the apparatus which reach the second electromagnetic valve 2A, are perfectly identical to those which have been shown in FIGS. 11 and 2.

As regards now the embodiment shown in FIGS. 5 and 6, it should be observed that in this Figure all the component parts which have been shown in FIGS. 3 and 4 can be found, with the addition of a third electromagnetic valve, ZB, having two ways which is synchronized, as usual, with the other two

electromagnetic valves

2, and 2A. To the electromagnetic valve 28 arrive, on the one side, the pipe TB which connects the valve to the piston 3, and, on the other side, a pipe section which is inserted between the two

branches

1A and 1C connected to the compressed air source I. The branch 1C, which is an extension of the branch 1A, is connected again to the electromagnetic valve 2A, in a manner which is similar to what has been seen for the previously described embodiments. The operation of the embodiment of FIGS. 5 and 6 is very much the same as that of the previously described embodiments: there is only to observe that the discharge of the cylinder of 3 as well as its charging, as regards the chamber placed at the right of the piston 3, as viewed in the drawings, are entrusted to a specially provided member, that is, the supplementary electromagnetic valve 2B as indicated above.

Summing up as regards the embodiment of FIGS. 5 and 6, the operational stages are the following:

1. Charging the cylinder of 3 through 1-2-4 and discharging the right portion of 3 through 113 and the electromagnetic valve 2B: the electromagnetic valve does not receive air from 1A. Simultaneously, R is charged through RA and 1C and the electromagnetic valve 2A, while 5 is being discharged through 6A and 7A, (FIG. 6).

2. Discharging 3 through 4, electromagnetic valve 2 and restrictor 7 while the right portion of 3 is charged through lA-2B-llB, the electromagnetic valve 2A being closed towards the branch 1C of the air feed. At the same time, R, through 4A, the

electromagnetic valve

2A and 6, charges the piston 5 and causes the discs to be spread out. The opening speed and time for the discs are determined by the calibration of the restrictor 7A, as has already been shown, and by the volurne of the reservoir R.

3. The same sequence as for ll) so that the operational cycle is closed and is repeated indefinitely.

In the drawings, as is customary, the closely scattered dots represent high pressure (that is, air feed) and the thinly scattered dots represent low pressure, that is, discharge of air, either directly or through the restrictor.

FIG. 7 gives a summary showing of the embodiments which have been described above: in this Figure there have been indicated in an extremely diagrammatical manner the functional connections and the positions of the several component parts as indicated in the other Figures: S symbolically connotes the electric synchronizing device for the positioning of the needle, whereas the other numerals remind the parts described in the Figures from I to 6, to show, in a simplified but sufficiently clear way, how the several operative members are connected with each other.

What is claimed is:

l. A device for synchronizing the slackening of the tension of the needle thread and the cutting, with timing of the slackening of the thread tension and independent control of the delay of the opening of the disc, for

lockstitch sewing machines, characterized in that it essentially comprises:

a pneumatic device for cutting the thread, having an input for compressed air;

a pneumatic device for controlling the thread tension, having an input for the air and an air output terminated by a flow regulator;

a source of compressed air;

a storage reservoir for compressed air;

a first control valve means, magnetically actuated and connected to said thread cutting device as well as to a flow regulator;

said first magnetically actuated valve means having a first position for connecting said compressed air source to the air input of said thread cutting device, and a second position for connecting the air input of said thread cutting device to the flow regulator belonging to said first valve means;

said second magnetically actuated valve means having a first position for connecting said compressed air source to said compressed air storage reservoir, and a second position for connecting said compressed air storage reservoir to the air input of said thread tension control device, and

means for positioning, alternatingly and simultaneously, said first and said second magnetically actuated valve means into said first or said second positions.

2. A device according to claim 1, characterized in that said thread cutting control pneumatic device further comprises a second input for compressed air connected by a pipe to a further way of said first valve means.

3. A device according to claim 1, characterized in that it comprises an additional valve means, synchronized with said first and second valve means, for controlling the feed and the discharge of the compressed air coming from said source to said second input for compressed air of said pneumatic thread cutting device, a piping being provided for connecting said second input to said additional valve means.

Claims

1. A device for synchronizing the slackening of the tension of the needle thread and the cutting, with timing of the slackening of the thread tension and independent control of the delay of the opening of the disc, for lockstitch sewing machines, characterized in that it essentially comprises: a pneumatic device for cutting the thread, having an input for compressed air; a pneumatic device for controlling the thread tension, having an input for the air and an air output terminated by a flow regulator; a source of compressed air; a storage reservoir for compressed air; a first control valve means, magnetically actuated and connected to said thread cutting device as well as to a flow regulator; a second control valve means, magnetically actuated and connected to said thread tension control device as well as to said compressed air storage reservoir; said first magnetically actuated valve means having a first position for connecting said compressed air source to the air input of said thread cutting device, and a second position for connecting the air input of said thread cutting device to the flow regulator belonging to said first valve means; said second magnetically actuated valve means having a first position for connecting said compressed air source to said compressed air storage reservoir, and a second position for connecting said compressed air storage reservoir to the air input of said thread tension control device, and means for positioning, alternatingly and simultaneously, said first and said second magnetically actuated valve means into said first or said second positions.