JPH0779893B2 - Length control mechanism for needle thread sewing start in lockstitch sewing machines - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a needle thread sewing start length control mechanism in a lockstitch sewing machine for eliminating thread balls formed on the back surface of a sewing start portion.

[Conventional technology]

The finished shape (arrow A) of the sewing start thread by the lockstitch sewing machine that is sewn with the upper thread and the lower thread is as shown in FIG.

That is, the upper thread a extending to the back surface of the cloth c is entangled in the seam of the upper thread b by the start of sewing and forms a so-called "thread ball d", which is not a beautiful finish.

At the beginning of the above-mentioned conventional sewing, in order to eliminate or shorten the upper thread a, which is formed with a long length of the thread ball d, in order to eliminate or shorten the upper thread a, the length of the remaining thread at the time of the thread trimming operation at the end of sewing (first thread tension device) The length from 201 to the upper thread end) must be constant. However, it is difficult to make the length of the remaining thread constant due to variable factors such as the strength of the first thread tension regulator 201, the strength of the thread tension spring 203, and the resistance characteristics of the thread to be used, which causes a large variation. Met. And even if these conditions can be kept constant, it is necessary to establish a technique to eliminate the "thread slipping out" at the first needle or the second needle. The technology to eliminate the ball d has not been established.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above problems, and a needle thread sewing start length control mechanism in a lockstitch sewing machine that can eliminate a thread ball at the start of sewing and perform accurate sewing at a desired sewing start dimension. It is intended to be provided.

[Means for Solving the Problems]

That is, the upper thread sewing start length control mechanism in the lockstitch sewing machine according to the present invention includes a wiper for removing the upper thread penetrating the cloth under the needle of the lockstitch sewing machine, and a wiper provided in the operation range of the wiper. A thread holding detection means comprising a thread holding detection mechanism that holds the end portion of the upper thread that is guided and outputs a detected signal indicating the presence or absence of the upper thread to the central controller.
By an actuator that is provided between the thread tensioner that applies tension to the upper thread and the upper thread supply section and that forms a sliding contact or a transit structure with the upper thread and that controls the sliding contact or the transit structure by a central control device. A thread pull-back mechanism configured to pull back the upper thread to the supply side according to the control amount, and after the upper thread and the lower thread are automatically cut at the end of sewing, the wiper of the thread holding detection means is operated to end the upper thread. After driving the thread holding detection mechanism to hold it, the thread holding detection mechanism detects the end of the upper thread and then pulls the upper thread back by the set upper pullback amount. The gist of the present invention is that it is configured with a central control device that is made up of

Further, in the above-mentioned configuration, a thread that is capable of adjusting the thread length of the upper thread in the thread path between the sewing machine needle and the balance is switched between an intermediate state and a non-intermediate state by an actuator controlled and controlled by the central controller. It is preferable to provide a length correction mechanism. Further, it is necessary to keep the main spindle of the sewing machine constant at all times, and the main spindle stop position correcting mechanism for detecting the main spindle position of the sewing machine stopped at the end of sewing and mechanically correcting the stop position by driving the actuator. Alternatively, the main spindle position of the sewing machine stopped at the end of sewing is detected, and the stop position is input to the central control unit by an input value from a stop position detection mechanism, and a detection means such as an encoder rotationally connected to the main spindle is used. It is desirable to provide a spindle stop position correction mechanism that electrically corrects the stop position by the central controller.

[Action]

According to the above configuration, when the upper thread and the lower thread are automatically cut at the end of sewing, the wiper removes the upper thread penetrating the cloth,
At this time, the end portion of the upper thread is held by the thread holding detection mechanism provided in the operation area of the wiper. In this state, the yarn holding detection mechanism outputs "present" of the yarn to the central controller. The main shaft of the sewing machine stopped at the end of sewing is corrected to a fixed position by the main shaft stop position correction mechanism so that the stop positions of the balance and the sewing machine needle are always stopped at fixed positions. The needle thread whose end is held by the thread holding mechanism is continued to the thread pull-back mechanism that pulls the upper thread back through the thread length correction mechanism that corrects the sewing start length. The mechanism is controlled and driven, the thread pullback operation is performed until the end of the upper thread is detected by the thread holding detection mechanism, and after pulling back the thread by the set thread pullback amount,
By turning off the thread pullback mechanism and the thread length correction mechanism, a preferable sewing start length of the upper thread can be set.

〔Example〕

An embodiment of a needle thread sewing start length control mechanism in a lockstitch sewing machine according to the present invention will be described below with reference to the drawings.

1 and 2 show the entire structure of a lockstitch sewing machine equipped with the control mechanism of the present invention, the operation of which will be described with reference to the flow chart showing the sequence control of FIG. Code 1
After the upper thread a and the lower thread b are automatically cut at the end of sewing, the upper thread a penetrating the cloth c is pulled out by the wiper 11, and at this time, the end portion of the upper thread a is in the operation range of the wiper 11. It is a thread holding detecting means held by a thread holding detecting mechanism 12 provided in the. Further, reference numeral 2 is the spindle 101 stopped at the end of sewing.
Is a main spindle stop position correction mechanism that corrects the stop positions (stop positions of the balance 8 and the sewing machine needle 9) to eliminate variations and constantly stops the main spindle at a fixed position. The needle thread a whose end is held by the thread holding mechanism 1 continues to the thread pull-back mechanism 4 that pulls back the upper thread a via the thread length correction mechanism 3 that corrects the sewing start length. Mechanism 4 is the thread holding detection mechanism 12
The yarn pull-back operation is performed until the end of the upper yarn a is detected by, and the yarn is pulled back by the set yarn pull-back amount [L], and then the yarn pull-back mechanism 4 and the yarn length correction mechanism 3 are OF
F Reference numeral 5 is a central control unit for performing sequence control (see FIG. 3) of the operations of the respective mechanisms and the sewing machine, and setting a preferable sewing start length of the upper thread a.

Next, an embodiment of each mechanism will be described in detail with reference to the drawings.

FIG. 4 shows a wiper 11 of the thread holding detecting means 1, which comprises the wiper 11 and a thread holding detecting mechanism 12 which will be described later, which are fixed to the sewing machine main body 10 via a bracket 13 and a fixing metal fitting 14. The wiper 11 has a base end of a wire rod 111 rotatably attached to a wiper drive shaft, and a hook end 112 having a bent tip is reciprocally oscillated in an arc shape along a locus L1. 111 is a sewing needle 9
The hook end 112, which is bent so as to pass the outside of the thread and hooks the upper thread a, has a shape as flat as possible so as to reduce the passing resistance of the thread holding detection mechanism 12. The wiper
Similarly to a wiper which has been conventionally used, 11 performs an operation of pulling out the upper thread a from the cloth c and then holding the end of the upper thread a in the thread holding detection mechanism 12.

FIG. 5 shows the yarn holding detection mechanism 12.

A contact spring 123 is fixed to a main body 121 fixed to the bracket 13 with an insulating plate 122 interposed therebetween. The main body 121 is grounded, and the contact spring 123 constitutes a yarn end contact type detecting means for outputting a contact signal to the central control unit 5 via a lead wire 127. The thread clip portion 124 and the contact point 125 of the contact point spring 123 have an independent structure, and the auxiliary spring 126 elastically urges so as to increase the restoring force, and the depression 128 is formed between the thread clip portion 124 and the contact point portion 125. I will do it. Due to the structure of the depression 128, the contact type detecting means prevents the insulating lubricant such as wax contained in the yarn from adhering to the contact portion 125, and can prevent the increase of the contact electric resistance. In addition, the protective cover 129 that covers the thread holding and detecting mechanism 12 has the tip of the wiper 1
It comprises a notch 130 for the passage of 1. The thread holding detection mechanism 12 opens the contact 125 when the upper thread a is held in the thread pinched portion 124 near the needle center P1 and closes the contact 125 when the upper thread a is no longer present. To detect. It is necessary to hold the sandwiched yarn with a weak force of 1 to 5 g. In order to quickly grasp the yarn at the moment when the wiper 11 passes, the inertia of the contact spring 123 is made as small as possible and the restoring force is provided by the auxiliary spring 126. The structure is enhanced.

Further, the bracket 13 constitutes a structure elongated hole type mounting position adjusting mechanism 131 which is adjustable in the radial direction with respect to a fixing metal fitting 14 having the same swing center as the rotation center C1 of the wiper 11 (see FIG. 4 (a)). ), The thread detection position adjustment of the thread holding detection mechanism 12 with respect to the swing locus L1 of the wiper 11 is facilitated.

6 and 7 show the spindle stop position correction mechanism 2.

The spindle drive band 21 has a ratchet pawl receiving cutout on part of the circumference
Makes up 23. The actuator 24, which is sequence-controlled by the central controller 5, has a return spring 25 and a stopper 26 for limiting the operating angle so as to rotate and drive in the direction of arrow F1, and the lever 27 fixed to the drive shaft is linked with the ratchet 28. The ratchet 28 has a buffer spring 29 at its tip, and is elastically biased by a spring 210 in a direction in which the ratchet 28 is in contact with the main shaft drive band 21. However, the actuator 24
In the OFF state, the ratchet 28 is separated from the band 21 and stands still as shown in FIG. 7A by the elastic return by the both springs 25 and 210 and the stopper 211. When the actuator 24 is turned on, the lever 28 rotates in the direction of arrow F1, and the ratchet 28 projects leftward to rotationally displace the position T1 of the notch 23 of the spindle drive band 21 to the fixed position T2. In this example, a rotary solenoid is used as the actuator 24, and the thrust of the reaction force spring 214 and the spring 210 in the radial direction of the spindle adapts to the instantaneous operation, and the overrun of the spindle 101 at the time of stop is prevented (the stop position is T2. It is.)

Further, in the above configuration, since the ratchet mechanism is configured to adjust and drive the spindle 101 stop position T2, even if the sewing machine is operated by mistake while the spindle stop position correction mechanism 2 is driven, the notch is notched.
It has a safe structure that interferes with the ratchet 28 from 23.

If a stepper motor is used as the actuator, shock is not generated, so buffer spring 29 and return spring 210
And the reaction force spring 214 can be omitted.

FIG. 8 shows the yarn length correction mechanism 3.

The bracket 37 fixed to the sewing machine body 10 has a solenoid 31
An actuator formed by mounting a T-shaped rod 32 elastically biased in the backward direction (arrow) by a return spring 36 is fixed to the tip of the iron core. A stopper 33 formed of a screw shaft is screwed into the bracket 37 at a protruding position of the rod 32 so as to face the rod 32 so that the rod 32 can advance and retreat. A U-shaped guide 34 is provided so as to project. However, when the solenoid 31 is turned on, the rod 32 slides and displaces to the right in the figure, abuts against the stopper 33, and stops. Due to the displacement of the rod 32, the upper thread a is U-shaped guide 34
Due to the relationship with the above, it is bent into a V shape as shown by the one-dot chain line, and this passing length becomes loose and when the solenoid 31 is turned off immediately before sewing, the rod 32 returns to its original position by the return spring 36, and the solenoid 31 is ON / OFF by central control unit 5
The needle thread a can be loosened to a certain size by controlling.

The thread length correction mechanism 3 having the above-described structure is configured to allow the needle thread a at the start of sewing to be
It is an adjustment mechanism that eliminates the "missing tail". When the cloth presser 6 is lowered immediately before sewing, the guide 7 is lowered in conjunction with the cloth presser 6. At the start of sewing, the balance 8 moves up and the sewing machine needle 9 moves down. Through this series of operations, the thread length correcting mechanism 3 takes "looseness" to stabilize the needle tip so that the needle thread a does not come off from the sewing machine needle 9.

Another function is to correct the yarn length during the yarn pullback operation by the yarn pullback mechanism 4, which will be described later, and the yarn pullback operation is performed when the cloth presser 6 and the guide 7 are raised. Since the guide 7 descends at the time of sewing, it is necessary to allow a margin for the thread. Further, a thread holding detection mechanism 1 for determining the thread length of the needle tip
It is also used when the position of is properly adjusted, and the adjustment is performed by moving the stopper 33 forward and backward.

FIG. 9 shows the thread pullback mechanism 4.

A motor 41 is fixed to a bracket 411 fixed to the sewing machine main body 10, and the roller 41 is provided in proximity to a rotation shaft 42 of the motor 41.
43 will be installed. The roller 43 is fixed to a pressing lever 45, one end of which is pivotally attached 412 to the bracket 411, and elastically attached in a direction F2 which is always in close contact with the rotating shaft 42 by a plate spring 49 inserted between the lower surface of the pressing lever 45 and the bracket 411. It will be energized. The other end of the pressing lever 45 is, as shown in FIG. 9 (d), an operating shaft 413 of a solenoid 46 fixed to a bracket 411.
And a swinging end of a lever 47 that is swingably pivoted around a pin shaft 414 as a swinging center so as to engage with the arrow F2 in the opposite direction. The pressing lever 45 has a structure in which it is pushed down against the elasticity of the plate spring 49 by the elasticity of the dissociation spring 48 that is pulled and elastically urged between the swing end of the lever 47 and the bracket 411, and the solenoid 46 operates. While the lever is in motion, the lever 47 resists the dissociation spring 48 and the arrow F3
It swings in the direction and is separated from the pressing lever 45. Therefore, the roller 43 is brought into contact with the rotary shaft 42 by the pressing lever 45, and the upper thread a is held between the rollers 43 and fed back in the direction of arrow F4 by the drive of the motor 41. The outer circumference of the rotary shaft 42 is finely knurled, and a rubber liner is attached to the outer circumference of the roller 43 to increase the frictional force with the upper thread a, thereby increasing the feed sliding force of the thread pullback mechanism 4. It becomes the structure.

Incidentally, reference numeral 410 is a yarn guide for regulating the yarn path of the upper yarn a.

In the thread pullback mechanism 4, when the solenoid 46 is turned off, the elasticity of the disengagement spring 48 causes the roller 43 to separate from the rotary shaft 42, and releases the upper thread a. The motor 41 uses a stepping motor and is rotationally controlled by the central control mechanism 5, and the yarn holding yarn detecting mechanism of the yarn holding detecting means 1 described above is used.
The yarn is fed until 12 detects the end of the upper yarn a, then the yarn is fed by the additional pullback amount [L], and then stopped.

In the embodiment of the thread pulling-back mechanism 4, one roller 43, which slides away from and in contact with the rotary shaft 42 of the motor 41, is pivotally mounted on the pressing lever 45. In order to increase the pulling force, as shown in FIG.
It is also possible to configure the pressing lever 45 arranged so that the two rollers 43, 43 are in contact with each other.

Further, in the embodiment of the thread pullback mechanism described above, the one provided between the upper thread supply source and the second thread tensioner 202 is shown, but between the first thread tensioner 201 and the second thread tensioner 202. It may be provided.

Further, the control device 5 has a central control circuit 51 as shown in FIG.
Memory circuit 52 connected to the controller and setter 53 for inputting control values
Is configured to perform the sequence control of each mechanism described above and at the same time perform the calculation according to the control numerical value from the setter 53 to drive and control each control drive device via the driver 54. Therefore, the setter 53 can set the yarn length in the range of 0 to 15 mm.

According to the needle thread sewing start length control mechanism in the lockstitch sewing machine having the above-described structure, the control device 5 performs sequence control according to the flowchart shown in FIG. 3, and the length 1 of the needle thread a at the sewing start is adjusted to the minimum. Because it is possible to
As shown in FIG. 11, a so-called "thread ball" in which the upper thread a is entangled with the lower thread b on the back surface of the cloth c is not formed.

Further, FIG. 12 shows another embodiment of the spindle stop position correcting mechanism. FIG. 12 (a) shows a spindle stop position detecting mechanism 20 in which an encoder 201 is directly connected to the spindle 101, and FIG. 12 (b) shows Spindle
A main shaft stop position detection mechanism 20 is provided with a graduation 202 on the outer peripheral portion of 101, and the graduation 202 is read by a photo reflector 203.

Each of the stop position detection mechanisms 20 inputs the stop position detection output to the central control unit 5, calculates the yarn pullback amount [L2] to be corrected by the software program according to the stop position of the spindle 101, and FIG. By operating the yarn pullback mechanism 4 according to the flowchart shown, the pullback correction of the upper yarn a corresponding to the stop position of the main shaft 101 is performed.

〔The invention's effect〕

As described above, the upper thread sewing start length control mechanism in the lockstitch sewing machine according to the present invention is controlled and driven by the thread holding detection means for detecting the end of the cut upper thread and the central controller, and the upper thread is supplied to the supply side. The thread pull-back mechanism that pulls the thread back into the machine makes it possible to keep the thread length after automatic thread cutting to a fixed length and to eliminate the slip-out during sewing, so the so-called "thread ball" at the beginning of sewing disappears. However, it has a characteristic that the finish after sewing is beautiful, and the effect after carrying out the present invention is extremely large.

[Brief description of drawings]

The drawings show a preferred embodiment of a needle thread sewing start length control mechanism in a lockstitch sewing machine according to the present invention. FIG. 1 is a perspective view showing the whole sewing machine equipped with the device of the present invention, and FIG. FIG. 4 is a front view showing the arrangement of the respective mechanical parts, FIG. 3 is a flow chart showing the sequence control of each part, and FIG. 4 is a wiper of the yarn holding detection means.
(A) is a front view, (b) is a left side view, FIG. 5 is a thread holding thread detection mechanism, (a) is a front sectional view,
(B) is a plan view, (c) is a right side view, FIG. 6 is a perspective view showing a spindle stop position correcting mechanism, FIG. 7 is the same mechanism, (a) is a front view, and (b) is a right side surface. FIGS. 8A and 8B show a yarn length correcting mechanism, FIG. 8A is a front view, FIG. 8B is a bottom view, and FIG. 9 is a yarn pulling-back mechanism. Front view, (b) is a plan view, (c) is a sectional view taken along the line CC of FIG. 9 (a), (d) is FIG. 9 (a).
Fig. 10 is a sectional view taken along line D-D in Fig. 10, Fig. 10 is a front view of a main part showing another embodiment of the thread pullback mechanism, Fig. 11 is an explanatory view showing stitches by a sewing machine equipped with the present invention, and Fig. 12 (a). ) And (b) are schematic front views showing other embodiments of the spindle stop position correcting mechanism, FIG. 13 is a flowchart showing a correction control method by the spindle stop position correcting mechanism, and FIG. 14 is a conventional sewing machine. It is explanatory drawing which shows a seam. 1 ...... Thread holding detection means 11 ...... Wiper, 14 ...... Fixing metal fitting 111 ...... Wiper rod 12 ...... Thread holding detection mechanism 121 ...... Main body, 123 ...... Contact spring 126 ...... Auxiliary spring, 129 ...... Protective cover 131 …… Mounting position adjustment mechanism 2 …… Spindle stop position correction mechanism 21 …… Spindle drive band, 23 …… Notch 24 …… Actuator, 27 …… Lever 28 …… Ratchet, 201 …… Encoder 202 …… Scale 203 ...... Photo reflector 3 ...... Thread length correction mechanism 31 ...... Solenoid, 32 ...... Rod 33 ...... Stopper, 34 ...... U-shaped guide 4 ...... Thread pullback mechanism 41 ...... Motor, 42 ...... Rotation shaft 43 ...... Roller, 45 …… Pressing lever 46 …… Solenoid, 47 …… Lever 5 …… Central control unit, 6 …… Cloth holder 7 …… Guide, 8 …… Balance 9 …… Sewing machine needle, 10 …… Sewing machine 101… … Spindle a …… Upper thread, b …… Lower thread c …… Cloth

Claims (4)

[Claims] 1. A wiper for removing an upper thread penetrating a cloth under a needle of a lockstitch sewing machine, and a wiper which is provided in an operation area of the wiper and which is guided by the wiper to hold and detect an end portion of the upper thread. A thread holding detection unit including a thread holding detection mechanism that outputs a signal indicating the presence or absence of the upper thread to the central controller, and a thread tension detector that applies tension to the upper thread and the upper thread supply source. A thread pull-back mechanism that configures a sliding contact or a passing structure, and pulls the upper thread back to the supply side according to a control amount by an actuator that controls and drives the sliding contact or the passing structure. After the thread and bobbin thread are automatically cut, the wiper of the thread holding detection means is operated to drive the end portion of the upper thread so that the thread holding detection mechanism holds the end portion of the upper thread, and the thread holding detection mechanism then drives the end of the upper thread. Is detected And a central control unit which drives the thread pullback mechanism in sequence so that the upper thread is pulled back by a preset amount of thread pullback. . 2. A thread length correction mechanism, which is provided in a thread path between the sewing machine needle and the balance, and which drives a thread passing structure capable of adjusting a thread passing length of an upper thread to be switched between a passing state and a non-passing state by an actuator. 2. The needle thread starting length control mechanism in a lockstitch sewing machine according to claim 1, wherein the mechanism is controlled and driven by the central controller. 3. A main shaft stop position correction mechanism for detecting the main shaft position of a sewing machine stopped at the end of sewing and mechanically correcting the stop position by driving an actuator at the stop position. An upper thread sewing start length control mechanism in the lockstitch sewing machine according to claim 1 or 2. 4. A detecting means, such as an encoder, which is rotationally connected to the spindle according to an input value from a stop position detecting mechanism for detecting the spindle position of the sewing machine stopped at the end of sewing and inputting the stopping position to the central control unit. The upper thread sewing start length control mechanism in a lockstitch sewing machine according to claim 1 or 2, further comprising a spindle stop position correcting mechanism for electrically correcting the stop position by a central control unit via the.