JPH03109095A - Sewing machine with thread-cutting function - Google Patents

Abstract

PURPOSE:To prevent a drawn thread from clinging to other members when the thread is cut, by a method wherein when a work is normally sewed, a thread-drawing means draws out the thread according to a first timing signal, and when the thread is cut by a thread-cutting means, a thread-drawing means draws out the thread according to a second timing signal. CONSTITUTION:When a start-stop switch 71 is operated, a control device 72 drives a sewing machine motor 85 and an arm shaft rotates. When the arm shaft rotates by an angle of 147 deg., a first timing signal FPS is generated by the device 72 from a first timing signal-generating device 74, and the amount of the thread to be drawn out is operated by the amount of a needle stroke, the amount of a feed, and thickness of a work. After that, a thread-drawing pulse motor 66 and a holding solenoid 65 are separately driven. When sewing is finished, a thread-cutting switch 73 is operated and a thread-cutting signal TCS is generated and the sewing machine motor 85 is driven at a low speed. When the arm shaft rotates by an angle of 287 deg., a second timing signal SPS is generated and the driving of both the thread-drawing pulse motor 66 and the holding solenoid 65 are controlled so that a needle thread Y1 is drawn out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thread trimming sewing machine, and more particularly to a thread trimming sewing machine that can pay out a predetermined amount of thread during thread trimming.

[Prior art] A sewing machine equipped with a conventional thread cutting device
A sewing machine described in Japanese Patent No. 7024 is known. This sewing machine is equipped with a thread feeding device, and during normal sewing, the upper shaft rotation angle is 90 degrees (the upper shaft rotation angle corresponding to the uppermost position of the sewing needle is 0 degrees), which is necessary for stitch formation. In addition, when cutting the thread, n times the amount of thread required to form the next stitch is paid out from the same point as during normal sewing.

[Problems to be Solved by the Invention] However, during thread trimming, the timing at which the movable blade captures the thread is much later than the timing at which the thread is paid out, so there is a problem that the paid out thread becomes loose and gets tangled with other members. There is a point.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a sewing machine equipped with a thread cutting device that can prevent the thread fed out during thread cutting from getting entangled with other members. It is in.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a sewing needle that can move up and down, a thread take-up means that performs a thread take-up movement in synchronization with the up and down movement of the sewing needle, It operates in synchronization with the vertical movement of the sewing needle, and includes a thread take-up means and a thread pay-out means for paying out the thread toward the sewing needle, and a thread that is connected between the sewing needle and the workpiece cloth and cuts the thread below the workpiece cloth. a thread cutter that operates, a first timing signal generating means that generates a first timing signal at a predetermined timing between when the sewing needle reaches the bed surface and when it reaches the lowest position; and a thread take-up means. a second timing signal generating means for generating a second timing signal at a specific timing corresponding to the vicinity of the maximum system relaxation position of the means; and control means for controlling the operation of the yarn feeding means in accordance with the second timing signal when the cutting means cuts the yarn.

[Function] In the sewing machine configured as described above, during normal sewing, the thread feeding means pays out the thread according to the first timing signal, and when the thread is cut by the thread cutting means, the thread is fed out according to the second timing signal. Bring out.

[Embodiment] Hereinafter, an embodiment of a sewing machine embodying the present invention will be described in detail with reference to the drawings.

First, to explain the thread trimming device gIC, as shown in FIG. A pot base 3 is provided. A horizontal hook 4 that rotates in a horizontal plane parallel to the throat plate 2 is provided on the hook base 3. The horizontal hook 4 includes an outer hook 5 that rotates around a vertical axis in a horizontal plane, an inner hook 7 that is held stationary within the outer hook 5 by a hook stopper 6, and a rotatably housed inside the inner hook 7. A bobbin 8 for bobbin thread is provided. A lower shaft 9 is rotatably supported within the bed portion 1 and extends from side to side through the pot base 3. The lower shaft 9 is disposed between the lower shaft 9 and the outer pot 5.
A gear transmission mechanism 10 is provided for transmitting the rotation of the rotor to the horizontal hook 4.

Then, according to the curve shown in FIG. 7, the needle 11 passes through the throat plate 2 and is moved up and down based on the rotation of the upper shaft (as shown), and in synchronization with the up and down movement, the horizontal hook 4 is moved to the second position. By rotating counterclockwise in the figure, stitches are formed on the work cloth W on the throat plate 2 shown in FIG. 5.

As shown in FIGS. 1 and 5, a thread guide 13 formed by bending an iron plate is swingable at an intermediate support portion 141 on a support shaft 12 protruding from the upper part of the hook base 3. It is supported and biased to swing clockwise in FIG. 5 by a spring 15 wound around the support shaft 12. The upper part of the thread guide body 13 extends left and right along the upper surface of the horizontal hook 4, and is swingable across the thread paths of the upper thread Y1 and lower thread Y2 between the throat plate 2 and the horizontal hook 4. A thread guide piece 16 is formed, and a follower piece 17 extending below the lower shaft 9 is formed at the lower part.

On the other hand, a driving body 21 is supported by the lower shaft 9 so as to be rotatable therewith and slidable in the axial direction of the lower shaft 9. A thread guide cam 22 as a first drive member which is eccentric with respect to the lower shaft 9 is formed on the right outer periphery of the drive body 21, and an eccentric part 23a similar to the thread guide cam 22 and a ridge are formed on the outer periphery of the intermediate part. A thread presser cam 23 is formed as a second driving member and includes a mold protrusion 23b, and an engagement groove 24 is formed on the outer periphery of the left side.

During normal sewing, based on the sliding movement of the driving body 21,
With the thread guide cam 22 engaged with the follower piece 17 of the thread guide 13, the drive body 21 is rotated together with the lower shaft 9, so that the thread guide 13 is rotated as shown in FIG. Due to the action of the thread guide cam 22, it is reciprocated and oscillated in synchronization with a thread take-up, which will be described later. Further, when cutting both the upper and lower threads Yl and Y2, the driver 21 is rotated integrally with the lower shaft 9 while the thread presser cam 23 is engaged with the follower piece 17, so that the thread guide member 13 is normally sewn. It is oscillated over a wider oscillation range than usual. That is, as shown by the solid line in FIG. 5, there is a retracted position where the thread is retracted upward from the thread path between the throat plate 2 and the horizontal hook 4, and as shown by the two-dot chain line in the same figure, both the upper and lower threads Yl, It is swung between the thread presser position and the thread presser position where both threads are bent by engagement with Y2.

A switching lever 25 is swingably supported at its base end on the bottom frame 1a of the bed section 1, and a pin 26 is protruded from the intermediate portion to engage the engagement groove 24 of the drive body 21 from below. ing. Further, as shown in FIGS. 1, 3, and 5, a connecting rod 27 is disposed on the bottom frame 1a so as to be movable left and right, and an intermediate protrusion 28 of the connecting rod 27 and the switching lever 25 are connected to each other. A spring 29 is hung between the switching levers 25 and 29 for constantly engaging the tip of the switching lever 25 with the intermediate protrusion 28.

When the connecting rod 27 is switched left and right by the action of the thread trimming solenoid 81 (see FIGS. 7 and 9), the intermediate protrusion 28 of the connecting rod 27 engages with the tip of the switching lever 25, and Through the engagement between the pin 26 of the switching lever 25 and the engagement groove 24 of the drive body 21, the drive body 21 is slid left and right on the lower shaft 9, and the thread guide cam 22 or the thread presser cam 23 moves the thread It is selectively engaged with the follower piece 17 of the guide body 13.

As shown in FIGS. 1 and 2, a support bracket 31 is disposed inside the bed portion 1 on the left side of the hook base 3, and a fixed blade 31 is provided on the rear upper surface of the support bracket 31, which is located close to the horizontal hook 4. 32 is attached.

A pair of guide rails 33 extending in parallel are attached to the upper surface of the support bracket 31 on the left side of the fixed blade 32, and along both guide rails 33, the solid line position and the two-dot chain line position in FIGS. 2 and 6 are arranged. A movable blade 34 is provided that can reciprocate between the two.

The movable blade 34 includes a pair of plates 35 and 36 that move together above and below the fixed blade 32, and the tips of both plates 35 and 36 are connected by a small piece 37 made of synthetic resin.

This small piece 37 is formed with a thread handling part 38 that enters into the upper thread loop when the movable blade 34 moves forward, and a thread hook part for catching both the upper and lower threads Yl and Y2 when the movable blade 34 moves backward. 39 is formed. This thread hook is part 39
The lower plate material 36 has both upper and lower threads Y1 and Y on the tip side.
A drawer part 40 is formed to secure the remaining amount of yarn after cutting No. 2, and the upper plate member 35 has a blade part that cuts both the upper and lower yarns Yl and Y2 in cooperation with the blade part 32a of the fixed blade 32. 34a is formed.

As shown in FIGS. 3 and 4, a movable blade operating lever 41 is swingably supported at the front end of the lower surface of the support bracket 31, and an arcuate escape hole 42 of the support bracket 31 is provided at the rear end. A connecting pin 43 is provided that penetrates and projects from the upper surface of the support bracket 31. This connecting bin 43
is engaged with a long hole 44 formed at the base end of the movable blade 34. Movable blade operating lever 41 and support bracket 31
A spring 45 is hung between the
The movable blade 34 is moved in the forward direction via the movable blade operating lever 41.
That is, it is biased to the right in FIG.

As shown in FIGS. 1, 3, and 4, a follower lever 46 is swingably supported at its rear end on the lower surface of the support bracket 31, and the movable blade actuating lever 41 is provided at its front end.
A connecting pin 48 that engages with the elongated hole 47 is provided in a protruding manner, and a cam follower 49 is provided in the intermediate portion to protrude downward. An intermediate lever 50 is swingably supported on the lower surface of the support bracket 31 at its intermediate portion so as to be located between the cam follower 49 and the connecting rod 27, and the cam follower 49 is attached to the upper arm of the intermediate lever 50. Lockable notch 52
is formed. Further, the lower arm portion of the intermediate lever 50 is connected to the connecting rod 27 by engagement with the pin 53 and the elongated hole 54.

A movable blade actuating cam 55 is integrally rotatably mounted on the lower shaft 9 so as to face the cam follower 49, and a cam groove 56 for reciprocating the movable blade 34 is formed on the periphery of the cam 55. When the connecting rod 27 is disposed at the leftward movement position, the cam follower 49 engages with the notch 52 of the intermediate lever 50 against the biasing force of the spring 45.
is removed from the movable blade operating cam 55.

Further, when the connecting rod 27 is moved rightward, the intermediate lever 50 is rotated counterclockwise in FIG. 3, and the notch 52 is disengaged from the cam follower 49, the biasing force of the spring 45 causes
The follower lever 46 is rotated slightly counterclockwise in FIG. 3, and the cam follower 49 is engaged with the movable blade actuating cam 55.

Next, to describe the thread feeding device T, as shown in FIG. A needle 11 is attached to the lower end of the rod 62. Further, a thread take-up 63 is provided in front of the head 61 and moves up and down in synchronization with the needle bar 62.

Again, a pair of thread clamping members 64 for clamping the upper thread Y1 are provided on the front side of the upper arm 60, and a clamping solenoid 65 is provided for causing the thread clamping members 64 to clamp the upper thread Y1. There is.

Further, a thread pay-out pulse motor 66 for paying out the upper thread Y1 is provided on the front face of the upper arm 60, and an output shaft of the thread pay-out pulse motor 66 has a rotating arm rotatable about a shaft 67. A driven roller 69 attached to one end of the rotating arm 68 is normally pressed against the driving roller 57 by a spring 51 attached to the other end of the rotating arm 68. The needle thread Y1 is then supplied to the needle 11 from a thread spool (not shown) via a pair of thread clamping members 64, a pair of rollers 69, 57, a thread hook member 58, a thread take-up spring device 59, and a thread take-up lever 63.

Next, the electrical configuration of the sewing machine of this embodiment will be explained with reference to FIG.

The pattern selection device 70 is configured to include a known operation switch and the like, and is configured to supply a pattern code signal MCS corresponding to the pattern selected by the operation of the switch to the control device 71.

The start/stop switch 71 is configured to generate an operation signal KS for starting or stopping the sewing machine when the start/stop switch 71 is operated. The thread trimming switch receives a thread trimming signal TC for driving the movable blade 34 and cutting the thread by its operation.
3. The first timing signal generator 74 is configured to generate a first timing signal FPS when the upper axis of the sewing machine reaches 147 degrees, as shown in FIG. The device 75 is configured to generate a second timing signal SPS at a point in time when the upper axis of the sewing machine is at 287 degrees. The thread detection device 76 is configured to generate a thread detection signal TKS corresponding to the detected thickness of the upper thread Y1.

The control device 72 is configured to operate according to a flowchart described later when each signal is supplied. R.O.
M77 stores stitch data of patterns selectable by the pattern selection device 70, and RAM78 stores stitch data of patterns selectable by the pattern selection device 70.
It is configured to temporarily store the calculation results of step 2 and the like.

The stitch forming device 79 includes a known needle bar swing mechanism and cloth feed control mechanism. The thread cutting solenoid 81 is configured to drive the connecting rod 27, and is connected to the control device 72 via a drive circuit 80. The yarn payout pulse motor 66 is connected to the control device 7 via a drive circuit 82.
2, and the clamping solenoid 65 is connected to the drive circuit 8.
The sewing machine motor 85 is connected to the control device 72 via a drive circuit 84 .

Now, when performing normal sewing in the sewing machine configured as described above, the thread trimming solenoid 81 is held in an inactive state and the connecting rod 27 is placed in the leftward movement position shown in FIG. Ru. In this state, the cam follower 49 is locked in the notch 52 of the intermediate lever 50, and the movable blade operating cam 5
5, and the follower lever 46 is disposed at the position shown in the figure.

Therefore, this follower lever 46 and the movable blade operating lever 41
The movable blade 34 is on standby at the solid line position in FIG. 2 via the movable blade 34.

Moreover, the intermediate protrusion 28 of the connecting rod 27 and the switching lever 25
Based on the engagement with the switching lever 25, the drive body 21 is moved to the leftward movement position shown in FIG. .

In this state, when the start/stop switch 71 is operated, the control device 72 detects that the operation signal KS has been generated at step STI (hereinafter referred to as ST1, and the same applies to other steps) in the flowchart of FIG. Then, the sewing machine motor 85 is driven at Sr1.

Then, when the upper shaft rotates by driving the sewing machine motor 85 and its rotation angle reaches 147 degrees, the first timing signal generator 74 generates the first timing signal FPS, and the control device 72 outputs the first timing signal FPS at Sr1. Detecting that the timing signal FPS 1 is generated, Sr1 calculates the amount of yarn to be fed out based on the needle swing amount, feed amount, and frost thickness, and operates the yarn feeding pulse motor 66 and the pinching solenoid according to the calculation result. 65 respectively.

Then, the operations from Sr1 to Sr1 are repeated until generation of the operation signal KS is detected at Sr1.

When the lower shaft 9 is rotated in the predetermined direction again by the drive of the sewing machine motor 85, the inner hook 7 of the horizontal hook 4 synchronizes with the vertical movement of the needle 11, with its rotation being restricted by the hook stopper 6. Then, the outer pot 5 is rotated counterclockwise in FIG. 2, and as shown in FIG. is given a feed.

In addition, as the lower shaft 9 rotates, the thread guide body 13 is swung in synchronization with the vertical movement of the thread take-up, as shown in FIG. The thread guide piece 16 engages with the lower thread Y2 between the throat plate 2 and the horizontal hook 4, and tension is applied to the lower thread Y2. Therefore, stitches with good thread tightness are formed on the work cloth W.

When the start/stop switch 71 is operated and the operation signal KS is generated, the control device 72 detects the generation of the operation signal KS at Sr1 and stops the sewing machine motor 85 at Sr1.

On the other hand, upon completion of the predetermined sewing, both the upper and lower threads Yl.

When the thread trimming switch 73 is operated to cut Y2 and the thread trimming signal TCS is generated, the control device 72
At r1, it is detected that the thread trimming signal TCS has been generated, and at Sr1, the sewing machine motor 85 is driven at a low speed. The sewing machine motor 85 is driven and the thread take-up lever 63 is lowered, thereby supplying the upper thread Y1 to the horizontal hook 4. However, when the rotation angle of the upper shaft reaches 147 degrees, the upper thread Y1 is still being supplied by the thread pay-out pulse motor 66. Since it is not fed out, an excess amount of upper thread Y1 is not generated and the upper thread Y1 does not get tangled with other members. And the rotation angle of the upper axis is 28
When the second timing signal generator 75 generates the second timing signal SPS when the temperature reaches 7 degrees, that is, when the balance 63 reaches the lowest position, the control device 72 outputs the second timing signal SPS.
1 detects that the second timing signal SPS is generated, and at 5TIO, the upper thread Y is set as in Sr1.
In order to feed out the yarn, the yarn feeding pulse motor 66 and the clamping solenoid are driven and controlled. Note that the amount of upper thread Y1 paid out during thread trimming is n times the amount paid out during normal stitch formation, and the amount of upper thread
It is controlled so that the larger the thickness of 1, the larger the amount is dispensed. Further, although a larger amount of needle thread Y1 is fed out at a later timing than during normal stitch formation, no problem occurs because the sewing machine motor 85 is driven at a low speed.

Then, the control device 72 drives the thread trimming solenoid 65 in the STI 1, and while the needle 11 is rising from the needle lower position, the thread trimming solenoid 65 operates to close the connecting rod 27.
is moved to the right. Based on this, the intermediate lever 50 is rotated counterclockwise in FIG.
Yes, the cam follower 49 is moved toward the movable blade actuating cam 55 via the movable blade actuating lever 41 and the follower lever 46, and is engaged with the cam 55.

In this state, the movable blade operating cam 5 is integrated with the lower shaft 9.
When the movable blade 5 is rotated, the movable blade 3 rotates according to the shape of the cam groove 56.
4 is reciprocated according to the curve shown in FIG. That is,
During forward movement, the movable blade 34 enters the needle thread loop from its thread handling portion 38. Thereafter, the blade portion 34a of the movable blade 34 and the blade portion 32a of the fixed blade 32 work together to cut both yarns Yl and Y2.

Further, as the connecting rod 27 moves to the right, the switching lever 25 is swung counterclockwise in FIG. 3 via the spring 29.
The driver 21 through the engagement between the pin 26 and the engagement groove 24.
is moved to the right, and the thread presser cam 23 is engaged with the follower piece 17 of the thread guide body 13. In this state, when the thread presser cam 23 is rotated together with the lower shaft 9, the thread presser cam 23
Due to the engagement between the protrusion 23b and the follower piece 17, as shown in FIG.
The thread guide body 13 is swung over a larger swiveling range than during normal sewing.

Based on this swinging of the thread guide body 13, the thread guide piece 16 moves to the fifth
It is swung between the retracted position shown by the solid line in the figure and the thread presser position shown by the two-dot chain line in the figure, and the throat plate 2. Both the upper and lower threads Y1, Y2 between the horizontal hooks 4 are bent, and the bent portions are arranged to cross the moving path of the movable blade 34. This state is maintained for almost the entire period during which the movable blade 34 moves back. Therefore, during the return movement of the movable blade 34, the supplementary operation of both the upper and lower yarns Yl and Y2 is reliably performed, and the subsequent uncutting operation is also performed smoothly.

When the control device 72 detects that the needle 11 has reached the raised position by a known needle-up detector after the thread trimming is completed, the controller 72 disables the thread trimming solenoid 65. Since the thread trimming solenoid has been switched to the inactive state, the connecting rod 27
is returned to the left, the cam follower 49 is separated from the movable blade actuating cam 55, and the thread guide cam 22 of the drive body 21 is again engaged with the follower piece 17 of the thread guide 13. Then, the control device 72 controls the sewing machine motor 85 in Sr1.
Stops driving.

[Effects of the Invention] As described in detail above, in the sewing machine of the present invention, by setting the timing at which the thread is let out during thread trimming to approximately the maximum system relaxation position of the thread take-up means, It is possible to prevent the yarn from being fed toward the hook and to prevent the excess yarn from getting entangled with other members.

[Brief explanation of drawings]

FIG. 1 is a plan view of a sewing machine embodying the present invention, and FIG. 2 is a plan cross-sectional view of the sewing machine with the bottom frame omitted.
Fig. 3 is a front sectional view, Fig. 4 is a side sectional view showing the movable blade actuation mechanism, Fig. 5 is a side sectional view showing the thread guide actuation mechanism, and Fig. 6 is a side sectional view showing the movable blade actuation mechanism.
The figure is a perspective view showing the movable blade and the fixed blade, Figure 7 is a graph showing the operation timing of each part with respect to the upper shaft angle of the sewing machine, Figure 8 is a front view of the upper arm of the sewing machine, and Figure 9 is the sewing machine. FIG. 10 is a block diagram showing the electrical configuration of the controller, and FIG. 10 is a flowchart showing the operation of the control device. In the figure, 11 is a needle, 63 is a balance, 72 is a control device, 74 is a first timing signal generator, 75 is a second timing signal generator, C is a thread cutter, and T is a thread payout device.

Claims (1)

[Scope of Claims] A sewing needle (11) that is movable up and down; a thread take-up means (63) that performs a thread take-up movement in synchronization with the up and down movement of the sewing needle (11); The needle thread (Y1) operates in synchronization with the vertical movement, and moves the upper thread (Y1) toward the thread take-up means (63) and the sewing needle (11).
), a thread cutting means (C) that operates to cut the thread connected between the sewing needle (11) and the workpiece cloth below the workpiece cloth, and the sewing needle (11) ) a first timing signal generating means (74) that generates a first timing signal (FPS) at a predetermined timing between when the bed surface (2) reaches the bed surface (2) and when it reaches the lowest position; The second timing signal (SPS) is output at a specific timing corresponding to the vicinity of the maximum system relaxation position of the thread take-up means (63).
); and a second timing signal generating means (75) that always controls the operation of the thread feeding means (T) according to the first timing signal (FPS), and A thread trimming sewing machine characterized by comprising: control means (72) for controlling the operation of the thread feeding means (T) in accordance with the second timing signal (SPS) during cutting.