JPS62120886A - Automatic stitch balaning thread tension apparatus of sewingmachine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) This invention relates to an automatic thread tension device for a sewing machine.

(Prior art) Traditionally, the tension of the upper thread has been determined by the operator checking the balance between the tension of the upper thread and the bobbin thread during sewing, and by observing the condition of the stitches each time sewing is performed. The device was manually operated to obtain the most appropriate tension. Since such a manual thread tension device requires skill on the part of the operator, there is a problem in that it is not always possible to obtain an appropriate thread tension for the upper thread. Therefore, without relying on such a manual thread tension device, the amount of thread consumption is calculated from the feed pitch, Ichihara, etc. conditions input before sewing, and the tension of the upper thread is adjusted by the manibulator based on the calculated results. Automatic thread tension devices that provide proper control have been put into practical use.

(Problem to be solved by the invention) However, since the automatic thread tension device described above inputs conditions such as cloth feed pitch and width before sewing, the thickness of the cloth to be sewn can be adjusted during sewing. When the thread speed changed or the &1 speed increased, the upper thread could not be adjusted accordingly.

(Objective of the invention) The present invention solves the above-mentioned problems, and after applying thread tension to the needle thread with the main thread tension device, even if the thickness of the work cloth changes during N-making, The sewing machine's automatic thread tension device allows you to change the needle thread tension to Luxi 1.
The purpose is to provide the following.

Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the automatic thread tension device of the present invention projects a detection light onto the work cloth on the work cloth feeding side from the needle drop point. , a detection means for detecting the amount of transmitted light, an additional tension applying means for applying variable thread tension to the upper thread in response to a control signal, and a change in the amount of transmitted light detected by the detection means. additional tension determining means for calculating and determining the magnitude of a control signal corresponding to the additional tension to be applied to the upper thread by the additional tension applying means based on the sewing pitch; and control for the additional tension applying means based on the sewing pitch. The device is equipped with a timing determining means for determining when to output a signal, and detects changes in stepped portions and density of the workpiece cloth during sewing as changes in the transmitted detection light, so that appropriate tension is always applied to the workpiece cloth. The gist of this is to ensure that

(Function) With the above configuration, the detection means detects the stepped portion of the work cloth during sewing, changes in density, etc. as the amount of change in the transmitted detection light. The additional tension determining means calculates and determines the magnitude of the control signal based on the change in the amount of transmission of the detection light detected by the detecting means.

Then, the timing determining means determines the time to output a control signal to the additional tension applying means based on the sewing pitch, and when the timing is reached, outputs the control signal to the additional tension applying means. Then, the additional tension applying means applies thread tension to the upper thread based on the control signal.

(Embodiment) An embodiment embodying the present invention will be described below with reference to FIGS. 1 to 8.

The sewing machine frame 1 includes an arm portion 2 and a bed portion 3,
A needle 5 is attached to a copper rod 4 mounted in the head of the arm portion 2 so as to be movable up and down. A light projector 6 constituting the thread material detector S is attached to the front surface of the head of the arm section 2, and as shown in FIG. It is screwed into a cylindrical housing portion 9a of a holder 9 fixed to the front surface of the head.

A transparent protection plate 8 is attached to the lower end of the housing tube 9a to prevent dust from adhering to the light emitting element 7.

A sliding plate 10 and a needle plate 11 are arranged on the bed portion 3, and a light receiver 14 is inserted into a fitting hole 13 formed in the needle plate 11 at a predetermined distance from the needle hole 12 toward the feeding side.
The upper part of the is fitted.

As shown in FIG. 1, the case 15 of the light receiver 14 has a base end fixed to the bed part 13 with screws, and a transparent protection plate 15a is attached to the upper end.

A light-receiving element 16 made of a phototransistor provided in the case 15 is arranged to face the light-emitting element 7, and directly receives the laser beam from the light-emitting element 7, as well as processing it. When the cloth N is fed from the feeding side to the sewing position and is blocked by the same work cloth N, it receives the light (transmitted light) from the light emitting cable 7 that passes through the work cloth N, and the A transmission signal is output based on the amount of transmission.

The light projector 6 and the light receiver 2S14 constitute a material detector S as a detection means.

An automatic thread tension device 17, which will be described later, is arranged above the 7-arm section 2, and a well-known main thread tension device 18, which can manually change the tension of the upper thread, is disposed on the front surface of the arm section 2. is attached, and a plurality of thread guide bodies 19 are also attached. Furthermore, a balance operated by a well-known balance mechanism is provided within the arm portion 2. The upper thread supplied from the upper thread supply source is supplied from the automatic thread tension device 17. Each thread guide 19. Main thread adjustment T device 18. The yarn is supplied to the needle 5 through the thread take-up, and the needle 5 and the yarn transport catcher (
(not shown), a wood seam is formed on the work cloth N.

Next, the automatic thread tension device 17 as an additional tension applying means is connected to the fourth
To explain in detail according to the drawings and FIG.
A mating hole 21a is bored from the front side, and a small diameter female threaded hole 21b is bored through the rear side.

A cylindrical rotating shaft 23 constituting the rotary thread tension device 22 is rotatably fitted into the fitting hole 21a, and a pair of discs 24 facing each other are provided on the front end surface of the rotating shaft 23. is fixed in one piece. The peripheral edges of both discs 24 are spaced apart from each other in opposite directions so that an upper thread can be wound thereon. The tip of the rotary thread tension plate 22 moves back and forth into the female screw hole 21b. It is rotatably inserted through the suture occlusion adjuster 25 which is screwed together so that the J4 joint can be screwed together.

A circumferential engagement groove 26 is formed on the outer periphery of the rear end of the rotating shaft 23, and an engaging step portion 27 is formed on the outer periphery of the front end of the rotating shaft 23. A bifurcated thread guide plate 28 through which the rotating shaft 23 is inserted is fixed to the front surface of the sub-tension holder 21.

Further, the thread guide sub-rod 25 has its head 25a and the disc 24.
Two springs that act during thread trimming are wound between the two springs so as to bias the rotary light control F-[n22 toward the sub-1 tension holder 21 through a friction plate 30 made of a friction material such as felt. It has become.

A holder 31 is fixed to the upper surface of the arm portion 2, and a servo solenoid 32 is fixed by screws to the upper part of one side of the holder 31 that projects upward. Further, an operating lever 3 is connected to a shaft 33 between the center portions of both side walls of the holder 31.
4 is rotatably supported by a shaft, and one end of the actuating lever 34 is linked to the lower end of the plunger 32a of the servo solenoid 32 via a link 35.

A spring 36 is wound around the shaft 33, one end of which is engaged with the holder 31, and the other end of the spring 36 is engaged with a engagement piece 34a formed on the upper part of the operating lever 34. , the front end of the operating lever 34 is always biased to rotate downward.

In the sub-tension holder 21, the upper part corresponding to the engagement groove 26 of the rotary thread tension disc 22 and the lower wall of the holder 31 have a lower end part that engages the rotating shaft 23 Fr42.
A tension applying pin 39 that abuts on the actuating lever 34 is inserted through the tension applying pin 39 so as to be able to move up and down, and the upper end of the tension applying pin 39 is brought into contact with the front end of the operating lever 34 so as to be driven.

Therefore, the rotary thread tension M1 of this automatic thread tension device 17
22 rotates when the upper thread U is moved in the supply direction with the upper thread tip attached to the periphery of the disc 24, and when the servo solenoid 32 is excited and the plunger 32a is driven, the link 35 and the operating lever 34, the pressing force of the additional bottle 39 against the engagement groove 26 is controlled.

Then, by controlling the pressing force of the tension adding bottle 39 against the engagement groove 26, resistance is applied to the rotation of the rotary light adjustment T-111122, thereby causing the tension to be wound between the discs 24 of the rotary thread tension 0n22. It is designed to adjust the tension of the upper thread.

In addition, as shown in Fig. 6, in this sewing machine, a well-known main shaft rotation angle detection device is installed at a pulley provided on the sewing machine main shaft (not shown) in the arm portion 2, or at a location where rotational drive is performed, such as a motor drive shaft. A device 40 is provided to constantly detect the rotation angle of the main shaft of the sewing machine and output the detection signal to an arithmetic circuit 43. Furthermore, a well-known sewing pitch detector 41 is installed at a location within the arm portion 2 that is linked to the cloth feeding mechanism, and detects the sewing pitch of the cloth feeding mechanism and outputs the detection signal to the calculation circuit 43. It looks like this.

The performance circuit 43 includes a central processing unit (hereinafter referred to as CPU) 44 as additional tension determining means and timing determining means;
It is composed of a read-only memory (hereinafter referred to as ROM) 45 and a read and occupy memory 46 (hereinafter referred to as RAM).

The input terminals of the CPU 44 are connected to the respective detectors S and 4.
0.41 is connected, and the servo solenoid 32 is also connected to the output terminal.

The ROM 45 contains a control program for controlling the CPLJ 44 and material detection position/needle groove lower ii! A plurality of functions (fpn) are also stored. In other words, the function fpn(T) is a function that expresses a certain relationship between the transmitted light attenuation rate R (transmitted light layer/light type) and the required needle thread tension T, as shown in FIG. A plurality of numbers are prepared corresponding to pn (n=1.2.3...).

The trial sewing switch 42 is provided on the pillar portion of the arm portion 2, and its output terminal is connected to the CPIJ 44,
The trial sewing mode and the lock stitching mode are selected by turning on and off the trial sewing switch 42.

Next, the operation of the sewing machine constructed as described above will be explained with reference to the block circuit diagram shown in FIG. 6 and the flow chart shown in FIG. 8.

Now, when trial sewing is to be performed, the trial sewing switch 42 is turned on to set the trial sewing mode. And the main thread tension device 1
8, place the part of the work cloth N on the fitting hole 13 of the throat plate 11, and perform trial sewing. Note that this trial sewing is preferably performed on a thin part of the work cloth N or a coarsely woven part.

At this time, the material detection 21iS applies the laser beam from the light projector 6 to the workpiece cloth N, and receives the transmitted light obtained through the workpiece cloth N with the light receiver 14. Then, the light receiver 14 outputs a transmission signal based on the amount of transmission to the CPIJ 44,
The PU 44 reads the detection signal when the balance position is at the top dead center (step 1).

That is, CPU44. The transmitted light is detected for each stitch of the needle 5.

Next, after detecting the transmitted light for each stitch, the CPU 44 determines whether or not the trial stitching switch 42 is turned on (step 2). When the trial sewing switch 44 is turned on, the CPU 44 outputs the transmitted signal. Initial data RO
It is stored in the RAM 46 as . Roughly speaking, the CPU 44 reads the detection signal detected from the sewing pitch detector 41 (step 3), and determines the material detection position based on the detection signal and the distance data between the material detection position and the needle drop position stored in the ROM 45. Transfer of the workpiece cloth N from vJ to the needle drop position
The time (that is, the number of steps M required to reach the needle drop position) is calculated, and the calculation result is stored in the RAM 46 (step 4).

Further, the CPU 44 selects a function f on (T) corresponding to the current sewing pitch pn based on the detection signal output from the sewing pitch detector 41 and records it in the RAM 46.
i-do (step 5). For example, when the sewing pitch is p1, the CPU 44 selects the function fpl(T) shown in FIG. 7, and when the sewing pitch is p2, the CPU 44 selects the function f p2 (T).

At this time, the CPU 44 calculates the required tension of the upper thread 0 based on the initial data RO and the selected function f pn (di), but the required tension r determined for the servo solenoid 32
The control signal corresponding to O is not output. That is, in the trial sewing mode, the operator applies tension TO to the upper thread U.
Manually adjust the main thread tension device 18 so that the

After this, when the trial sewing switch 42 is turned off and sewing is started in the lock stitch mode, the CPU 44 reads the transmission signal outputted from the material detector S for each stitch when the thread take-up position is at the top dead center (step 1). . And then CP
When U44 inputs data R1 based on the transmission signal output from material detector S, for example, when function f'pl(T) is selected, CP LJ 44 inputs data R1 based on the data R1 and function rp1(T). The necessary needle thread tension T1 is calculated, and ΔT=TI-To is calculated (step 6). Also, for example, when the function f' p2 (di) is selected, the CPU 44G,
2(T) Calculate the required tension T'1 of the Tokara needle thread, and further calculate WA by ΔT'=T1-T=0.

Then, the CPU 44 selects the applied current to be applied to the servo solenoid 32 based on the crushing result ΔT, etc., stores the calculated result in the RAM 46, and puts it in a standby state (step 7).

Further, in step 7, the CPtJ44 counts the number of stitches m since the data as a control signal indicating the magnitude of the applied current is stored in the RAM46, and calculates the counted number of stitches m from the number of stitches M stored in the RAM46. It is determined whether the subtraction result is 0 or not (step 8).

When the subtraction result is O, the CPU 44 inputs the detection signal from the spindle rotation angle detector 40 and determines whether the spindle rotation angle data based on the detection signal is within the range of 100° to 300'. (Step 9). When the spindle rotation angle is within the range of 100' to 300°, CPtJ44 waits for the applied current data corresponding to the calculation result of O (the number of stitches m matches the number of stitches M). The state is canceled, the applied current data is read from the RAM 46, and the applied current is output to the servo solenoid 32 of the automatic thread tension device 17. If the current is not within that range, the spindle rotation angle reaches the range of 100' to 300°. When this happens, the standby state is canceled, the applied current data is read from the RAM 46, and the applied current is applied to the servo solenoid 32 to apply the necessary needle thread tension to the needle thread opening (step 1).
0).

On the other hand, when it is determined in step 8 that CP tJ 44 is not O, the process returns to step 1, detects the transmitted light in the next stitch, and performs the same operation thereafter.

That is, CP (J44) stores the newly obtained applied current data in another address of the RAM 46, counts the number of stitches m' after the new applied current data is stored, and calculates the number of stitches m- as the number of stitches. Subtract it from the number M, and judge whether or not the subtraction result is O. At this time, there are a plurality of applied current data, and the stitch numbers m and m' are calculated for each of them.The CPU 44 When the movement from step 8 to step 1 is repeated the same number of times as the number of stitches M determined in step 4, (the part of the workpiece fabric that was at the material detection position at the start of sewing has reached the needle drop point) (time), the stitch count number m corresponding to the initially set applied current data matches M, the cylinder reduction result in step 8 becomes O, and the applied current is applied to the servo solenoid 32 in step 9.10. Thereafter, the process returns to step 1 from step 8 through step 9 and 10 every time one stitch is formed, so that an appropriate tension is always applied to the upper thread.

Note that when the material detector S again detects a thin part of the workpiece cloth N similar to the first time in the lockstitch mode in the state where the needle thread tension is applied, the current applied to the servo solenoid 32 is changed by following the same path. Then, the needle thread tension is set to the reference state initially applied by the automatic thread tensioner 17.

Although the detection position and needle drop position are separated in this way,
Since the applied current is applied to the automatic thread tension device 17 and the bosolenoid 32 with a time delay, an appropriate tension is always applied to the work cloth N. In addition, since the detection means uses transmitted light, it can deal with irregularities due to differences in the weaving of the work cloth N, as well as two-tiered sections on the right bank, etc., and since changes in transmitted light are constantly read, it is possible to increase speed. This is also possible. Further, it is possible to change the upper thread tension in response to changes in the work cloth N, which has not been functionally possible in the past.

Furthermore, since the detection means uses laser light as the detection light, it can also be applied to thick work cloths.

It should be noted that the present invention is not limited to the embodiments described above, and may be modified as desired without departing from the spirit of the invention.

Effects of the Invention As detailed above, this invention is capable of responding to changes in the thickness of the work cloth during A1, which was previously impossible, after setting the upper thread tension with the main thread tension device in advance. In addition to being able to flexibly change the upper thread tension, it also uses transmitted light as a detector, so it can handle not only fabric layers but also coarseness and density due to differences in material weaving methods, and can also be used for high-speed sewing. It has excellent effects that can be used.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view of a sewing machine embodying the present invention, Fig. 2 is a partially omitted side view, Fig. 3 is a plan view of the bed section, and Fig. 4 is an automatic thread tensioner. The front view of the device, Figure 5 is a side sectional view, and Figure 6 is an electrical block circuit diagram.
FIG. 7 is a graph showing the relationship between the transmitted light attenuation rate and the required tension of the upper thread, and FIG. 8 is a flowchart. Needle 5, light emitter 6, light emitter element 7, light receiver 14, light receiving element 1
6, automatic thread tension device 17, main thread tension device 18, rotary light adjustment plate 22, tension addition bin 39, main shaft rotation angle detector 40
, sewing pitch detection S! 841, arithmetic circuit 43, central processing unit (CPU) 44, ROM 45, RAM 46, material detector S, needle thread U0 Patent applicant Brother Industries, Ltd. Agent Patent attorney On 1) Hironobu No. 6
figure

Claims (1)

[Claims] 1. A sewing machine equipped with a needle (5) that moves up and down, and a main thread tension device (18) that can be operated by an operator to apply the required tension to the upper thread (U). , a detection means (S) for projecting a detection light onto the workpiece cloth (N) and detecting the amount of the transmitted light on the workpiece cloth feeding side than the falling point of the needle (5); and in response to a control signal, an additional tension applying means (17) for applying variable thread tension to the upper thread (U); and an additional tension applying means (17) for applying variable thread tension to the upper thread (U); additional tension determining means (44, step 6, step 7) that calculates and determines the magnitude of the control signal corresponding to the additional tension to be applied to the upper thread (U) in step 17); It is equipped with a timing determining means (44, step 8, step 9) for determining when to output a control signal to the additional tension applying means (17), and is capable of checking changes in the stepped portion and density of the workpiece cloth (N) during sewing. An automatic thread tension device for a sewing machine is characterized in that an appropriate tension is always applied to a work cloth (N) by detecting the amount of change in transmitted detection light.