JP2010263976A - Decorative stitch sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the sewing quality of a decorative stitch sewing machine by suppressing deficiency such as impairment of tightness of a thread just after change of the sewing direction. <P>SOLUTION: The decorative stitch sewing machine includes: a needle vertical moving mechanism for vertically moving a plurality of sewing needles 21 and 22; balances 51 an 52 for raising needle threads T of the respective sewing needles; an upper position detecting means for stopping the respective sewing needles at a position above a fabric; a presser foot 44 capable of switching between the pressing and releasing of a workpiece; a needle plate 100 having insertion parts 102 for the respective needles and a cantilevered needle plate pawl 101; and a thread tension mechanism 30 for applying the thread tension force to the respective needle threads of the sewing needles. The decorative stitch sewing machine also has a thread feeding mechanism 60 disposed in the space between the needle threads from the thread tension mechanism to the respective sewing needle for feeding the threads in an amount according to the rotation operation of the workpiece for the respective needle threads, and a control means 80 for controlling feeding of the needle threads by the thread feeding mechanisms when an upper position is detected and the sewing needles are stopped. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a decorative sewing machine.

The decorative sewing machine is sewn with a plurality of sewing needles (for example, 2 to 3) arranged in a direction perpendicular to the cloth feeding direction, and the sewing needles are arranged in the lower side of the cloth to be sewn. The looper thread crosses along the upper side and the upper decoration thread crosses along the direction in which the sewing needles are arranged on the upper side of the cloth.
A needle plate claw 101 extending in the cloth feeding direction F (downstream side) is formed between the needle drop holes 102 of each needle on the needle plate 100 of the decorative sewing machine (see FIG. 2). ) Immediately after the formation of the seam, the looper thread crosses over the throat plate claw 101 between the sewing needle and the needle plate claw 101 so that the looper thread is detached from the tip of the throat plate claw 101 as a few stitches are fed. (For example, refer to Patent Document 1).

JP-A 63-186688

By the way, in the conventional decorative sewing machine, when changing the sewing direction by square stitching, etc., the sewing machine is temporarily stopped so that the sewing needle is positioned above the cloth, the cloth presser is raised, and each thread is After releasing the thread tension mechanism of the fabric, the direction of the fabric was rotated. Since the next needle drop position of the plurality of sewing needles is moved by the rotation of the fabric (see arrow d in FIG. 5B), it is necessary to supply a needle thread for each sewing needle. Since the tension mechanism is released, the necessary needle thread can be easily fed out from the thread supply source.
However, since the rotation operation of the fabric is performed manually, it is difficult to rotate the fabric so that the feeding amount is minimized when the thread tension mechanism is in the released state.
Furthermore, when the fabric is rotated, the upper decorative thread is in a state of straddling the above-described needle plate claw 101. Therefore, before rotating the fabric, first, the upper decorative thread is needled by shifting the fabric in the cloth feeding direction. It was necessary to remove from the plate claw 101. For this reason, it has been very difficult to rotate the fabric so that the needle thread is not unreeled.
As a result, the needle thread is unwound excessively due to the rotation of the fabric, and there is a problem that the stitches at the start of sewing after changing the sewing direction are liable to cause poor thread tightening and deteriorate the sewing quality.

  An object of the present invention is to improve the sewing quality of a decorative sewing machine.

The invention described in claim 1 includes a needle up-and-down movement mechanism that moves up and down a plurality of sewing needles arranged in a direction intersecting the cloth feed direction, a balance that pulls up the needle thread of each sewing needle, An upper position detecting means for stopping the sewing needle at a position above the cloth, a cloth presser capable of pressing the sewing object at the time of sewing and releasing the sewing object by ascending, an insertion portion of each sewing needle and each of the sewing needles A needle plate having a cantilevered needle plate claw extending toward the downstream side in the cloth feed direction between the insertion portions; a thread tension mechanism for individually applying a thread tension to the needle thread of each sewing needle; In a decorative sewing machine comprising
Provided in the course of the needle thread path from the thread tension mechanism to each of the sewing needles, and individually for each of the needle threads in order to feed the thread according to the amount of rotation of the sewing product for changing the sewing direction. And a yarn feeding mechanism that feeds at each of the yarn feeding amounts, and when the sewing needle stops when the detection by the upper position detecting means is performed, the yarn feeding mechanism Control means for feeding out each needle thread is provided.

  The invention described in claim 2 has the same configuration as that of the invention described in claim 1, and the yarn feeding mechanism has a larger amount of needle thread outside than the amount of needle thread fed inside the cloth rotation corner. Thus, an adjustment unit for individually adjusting the feeding amount of each needle thread is provided.

  The invention described in claim 3 has the same configuration as that of the invention described in claim 1 or 2, and further includes an actuator for switching the cloth presser to a released state, and the control means is configured to control each needle thread by the thread feeding mechanism. In conjunction with the feeding, the actuator is controlled to switch the cloth presser to a released state.

  The invention according to claim 4 has the same configuration as that of the invention according to any one of claims 1 to 3, and the thread tension mechanism includes an actuator that switches to a release state in which no thread tension is applied, The control means is configured to perform control to maintain the thread tension mechanism in a non-released state with respect to the actuator at least after the needle thread is fed by the thread feeding mechanism while the sewing is stopped. To do.

  The invention described in claim 5 has the same configuration as that of the invention described in claim 4, and the control means is configured to adjust the thread tension of the thread tension mechanism during sewing while each needle thread is being fed by the thread feeding mechanism. It is characterized by reducing more.

  According to the first aspect of the present invention, since the control means feeds each needle thread in accordance with the amount of rotation of the cloth by the thread feeding mechanism when the sewing needle is stopped, the work for rotating the workpiece to change the sewing direction is performed. Sometimes it is not necessary to release the thread tension mechanism so that the needle thread can be delivered to the next needle entry position of each sewing needle. It is possible to avoid paying out extra needle thread due to the work for pulling out, to suppress a defect such as a decrease in thread tightening immediately after changing the sewing direction, and to improve the sewing quality in decorative sewing.

  According to a second aspect of the present invention, the yarn feeding mechanism adjusts the feeding amount of each needle thread individually so that the feeding amount of the outer needle thread is larger than the feeding amount of the needle thread inside the cloth rotation corner. The adjustment part of the sewing needle is provided so that when the sewing needles on the inner side and the outer side are known in the direction change work of the sewing product, the amount of change in the needle drop position of each sewing needle and the feeding of each needle thread are performed in advance. By setting the amount equal to each other, it is possible to perform the minimum necessary amount of thread feeding required for the direction change work of the sewing product, and to improve the thread tightening immediately after the direction change of the sewing, and to further improve the sewing quality in decorative sewing It is possible to improve.

  In the invention according to the third aspect, since the cloth presser is switched to the released state in conjunction with the feeding of each needle thread, it is possible to easily perform the rotation operation of the sewing product, and the operability is improved.

The invention according to claim 4 is in a state where the sewing is stopped for the rotational operation of the sewing product, and the thread tension mechanism is maintained in the non-released state at least after the feeding of each needle thread. It is possible to further improve the sewing quality in the decorative stitching by suppressing extra thread payout during the rotation operation of the object and making the thread tightening immediately after changing the sewing direction good.
Since “at least after each needle thread has been paid out”, the thread tension mechanism is kept in the non-released state even during the feeding, that is, while the sewing is stopped for the rotation operation of the sewing product. It may be kept in a non-released state.

  According to the fifth aspect of the present invention, the thread tension of the thread tension mechanism is reduced during sewing while the sewing operation is stopped for the rotational operation of the workpiece, and each needle thread is being fed out, thereby reducing the thread tension. The feeding can be performed smoothly, the thread can be fed with a more appropriate feeding amount, the thread tightening immediately after changing the sewing direction can be improved, and the sewing quality in decorative sewing can be further improved. Become.

It is a perspective view of the decorative sewing machine which is an embodiment of the invention. It is a top view of the needle plate of a decorative sewing machine. FIGS. 3A and 3B are operation explanatory views of the yarn delivery mechanism as viewed from the front, FIG. 3A showing a standby state and FIG. 3B showing a yarn delivery state. It is a block diagram which shows the control system of a decorative sewing machine. FIG. 5 (A) is an explanatory view showing a needle drop position when sewing a decorative stitch with two sewing needles and FIG. 5 (B) changes the direction of the sewing direction in the middle of the sewing. It is a flowchart which shows the process in the sewing operation | movement of a decorative sewing machine.

(Whole structure of the sewing machine)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a decorative sewing machine 10 according to the present embodiment. FIG. 1 is a perspective view of a decorative sewing machine 10.
As shown in FIG. 1, the decorative sewing machine 10 includes a main body frame 2 whose overall shape is a U-shape. The main body frame 2 is located at the lower part of the sewing machine 10 and stores a looper mechanism to be described later. Bed part 2a, sewing machine vertical body part 2b erected upward from one end part of sewing machine bed part 2a, and sewing machine arm part extending in the same direction as sewing machine bed part 2a from the upper end part of sewing machine vertical body part 2b 2c.
Here, in the following description, the direction along the longitudinal direction of the bed 2a of the main body frame 2 is defined as the Y-axis direction, and the direction perpendicular to the Y-axis direction that is the standing direction of the vertical trunk 2b is defined as the Z-axis direction. The direction orthogonal to both the Y-axis direction and the Z-axis direction is taken as the X-axis direction. Furthermore, in the state where the decorative sewing machine 10 is installed on the horizontal plane, the X-axis direction and the Y-axis direction are in a state along the horizontal plane, and the Z-axis direction is in a state along the vertical vertical movement direction. The decorative sewing machine 10 feeds the cloth along the X-axis direction.

  As shown in FIG. 1, the decorative sewing machine 10 has a needle bar 24 that holds two sewing needles 21 and 22 in a line along the Y-axis direction (direction perpendicular to the cloth feed direction) at the lower end. A needle up-and-down movement mechanism that moves the sewing needles 21 and 22 up and down, and a single looper 25 that moves forward and backward in synchronization with the vertical movement of the needle bar 24 below the needle plate 100 of the sewing machine bed 2a. The looper mechanism for inserting the looper thread L into the loop of the needle thread T passed through the sewing needles 21 and 22, and the spreader near the needle drop position of the sewing needles 21 and 22 above the needle plate 100. The spreader mechanism that sews the upper decoration thread S along the direction in which the sewing needles 21 and 22 are arranged by moving the needle 26 forward and backward, and each needle thread T that is fed from each thread supply source. , Looper thread L and upper decoration thread S individually A thread tension mechanism 30 that applies tension, a thread lubrication means 41 that supplies lubricating oil to each needle thread T on the downstream side of the thread tension mechanism 30, and a swing balance that swings in synchronization with the vertical movement of the needle bar 24. Each stitch after the loop is formed by the first balance mechanism 51 that pulls up the sewing needles 21 and 22 after the loop formation upward from the fabric side by 51 and the lift balance 52 that moves up and down in synchronization with the vertical movement of the needle bar 24. A second balance mechanism that pulls the needles 21 and 22 upward from the fabric side; a thread guide 43 that is provided at the lower end of the tip of the sewing machine arm portion 2 c and that has thread holes for individually inserting the needle threads T; A cloth presser 44 capable of pressing and releasing the sewing product while pressing the sewing product at the time of sewing, the needle plate 100 provided at the needle drop position on the upper surface of the sewing machine bed portion 2a, the thread tension mechanism 30, Each needle thread is arranged between the swing balance 51 The thread feeding mechanism 60 performs the yarn feeding, and a control unit 80 of each of the above structures.

(Needle vertical movement mechanism)
The needle up-and-down moving mechanism is disposed along the Y-axis direction in the sewing machine arm portion 2c and the needle bar 24 supported so as to reciprocate in the same direction in the state along the Z-axis direction on the distal end side of the sewing machine arm portion 2c. And a crank mechanism (not shown) that converts the rotational driving force of the sewing machine main shaft (not shown) into a reciprocating vertical driving force and applies it to the needle bar 24.
At the lower end of the needle bar 24, two sewing needles 21 and 22 are held in a line along the Y-axis direction, and each of these sewing needles 21 and 22 is a thing far from the machine vertical body 2b. Is held so that the tip has a lower height. That is, the sewing needle 21 is low and the sewing needle 22 is high and is held by the needle bar 24.
It is also possible to hold two or more sewing needles (for example, three) by exchanging the needle clamp 24a of the needle bar 24.

(Looper mechanism)
The looper mechanism includes a looper 25 inserted into the loop of each needle thread T formed when the sewing needles 21 and 22 are raised through the bottom dead center, and the Y-axis direction in the sewing machine bed portion 2a. A lower shaft (not shown) that rotates in synchronization with the main spindle of the sewing machine, a looper shaft 27 that is arranged along the Y-axis direction in the sewing machine bed portion 2a and that holds the looper 25 at the tip, and a lower shaft And a known transmission mechanism (not shown) for converting the rotational driving force into a reciprocating driving force in the thrust direction having the same frequency and applying it to the looper shaft 27.
The looper 25 extends along the Y-axis direction coinciding with the direction in which the sewing needles 21 and 22 are arranged, and the tip thereof is on the tip side of the sewing machine bed portion 2a (on the opposite side of the machine vertical body portion 2b). Direction) and is held at the tip of the looper shaft 27. Then, by the forward movement by the looper shaft 27, the sewing needle 22 and the sewing needle 21 are inserted into the loop of each needle thread T in the order. Thereby, the looper thread L guided to the tip part along the looper 25 is inserted into the loop of each needle thread T, and sewing is performed.

(Spreader mechanism)
The spreader mechanism includes a spreader 26 that is looped so that the upper decorative yarn S is folded at the tip, and a base portion of the spreader 26 along the Z-axis direction by converting the torque of the sewing machine main shaft into reciprocating rotational power having the same cycle. And a well-known transmission mechanism (not shown).
The distal end portion of the spreader 26 is slightly curved in an arc shape, and the distal end portion moves back and forth generally along the Y-axis direction by reciprocatingly swinging around the proximal end portion. A notch for hooking the upper decoration thread S is formed at the front end of the spreader 26. The lower end of the sewing machine arm 2c is adjacent to the needle bar 24. A loop of the upper decoration thread S is formed by a thread path leading to the sewing product through the notch at the front end portion, and the front end portion of the spreader 26 is moved generally along the Y-axis direction to advance the upper decoration thread S. The sewing needle 21 guides the inner area of the loop so as to drop the needle, and moves backward after the needle drop, so that the upper decoration thread S is stretched along the direction in which the sewing needles 21 and 22 are arranged. The spreader 26 is sewn so as to meander by the sewing needles 21 and 22 on the upper surface of the fabric by performing the above-described advance / retreat movement in accordance with the vertical movement cycle of the sewing needles 21 and 22.

(Thread tension mechanism)
The thread tension mechanism 30 is arranged on the side surface of the vertical machine body 2b of the sewing machine, and is provided with four needle threads T, upper decoration threads S, and looper threads L corresponding to the sewing needles 21 and 22, respectively. Thread tensions 31, 32, 34, and 35 are provided. In addition, assuming that three sewing needles are used and three needle threads are used, a third thread tension 33 is also provided. Each of the thread tensions 31 to 35 includes a pair of thread tension dishes for holding the thread, an elastic body that presses the thread tension dishes together, and a knob that adjusts the pressure contact force of the elastic body. With this configuration, each thread tension is adjusted to an appropriate pressure contact force with a knob, and a resistance force is applied in the feeding direction by pinching each thread to generate an appropriate tension in each thread.
The thread tension mechanism 30 is not shown in the figure, but a release claw member that releases the thread by forcibly pushing it between the thread tension trays that form pairs of the thread tensions 31 to 35, and A yarn release solenoid 36 (see FIG. 4) is provided as an actuator for giving a release operation to the release claw member.

The looper yarn L is unwound from a yarn supply source (not shown), is stretched over the thread tension 35, is guided to the looper 25 through the inside of the sewing machine bed portion 2a.
The upper decorative yarn S is unwound from a yarn supply source (not shown), and is passed over the thread tension 34, and then the sewing machine arm portion is provided by a looper yarn guide 38 provided at a lower portion on the base end side of the sewing machine arm portion 2c. 2c is guided to the tip of the spreader 26 via a looper thread tension 37 and a decorative yarn guide 28 provided on the side surface of the tip of the sewing machine arm 2c.

(Thread lubrication means, thread guide, etc.)
The thread lubricating means 41 is provided on the side surface of the base end of the sewing machine arm portion 2c, and has a structure for supplying lubricating oil to the needle threads T that have passed through the thread tension mechanism 30 by passing them.
The yarn guide 43 is disposed at the lower part of the side surface of the distal end portion of the sewing machine arm portion 2c. The thread guide 43 is provided with a threading hole through which the two needle threads T are individually passed. The thread guide 43 is formed with three threading holes through which three needle threads are inserted, corresponding to the case where three sewing needles are used. These three threading holes are formed side by side along the Y-axis direction. The needle thread passed through the threading holes of the thread guide 43 is guided to the sewing needles 21 and 22.

(First balance mechanism)
The first and second balance mechanisms are disposed between the thread tension mechanism 30 and the thread guide 43 on the side surface of the sewing machine arm portion 2c and in the thread path. The first balance mechanism includes a swing balance 51 that swings up and down a distal end portion having a threading hole through which each needle thread T is individually passed, and a base end portion of the swing balance 51 around the X axis. And a well-known transmission mechanism (not shown) that converts the rotational driving force of the main spindle of the sewing machine into a reciprocating swinging driving force around the X-axis and imparting it to the swinging balance 51.
The swing balance 51 is formed with three threading holes arranged in the X-axis direction at the tip so that it can be used even when three sewing needles are used. When two sewing needles are used, two of these threading holes are used.
The transmission mechanism that pivotally supports the base end portion of the swing balance 51 applies a swing driving force around the X axis, so that the tip portion moves up and down while drawing a circular locus. The swing angle of the tip of the swing balance 51 can be adjusted by a transmission mechanism.

(Second balance mechanism)
The second balance mechanism is disposed on the upper surface of the distal end portion of the sewing machine arm portion 2c, and is disposed immediately downstream of the first balance mechanism with respect to the thread path of the needle thread. The second balance mechanism includes a lifting / lowering balance 52 that swings an upper end portion having a threading hole through which each needle thread T is individually passed, and a rotational driving force of the sewing machine spindle along the Z-axis direction. A well-known transmission mechanism (not shown) that converts the driving force into a vertically moving drive force and applies it to the lifting / lowering balance 52 is provided.
The lifting / lowering balance 52 is formed when three threading holes are formed in the X-axis direction at the tip so that it can be used even when three sewing needles are used, and there are two sewing needles. Two of these threading holes are used. Each needle thread passed through each threading hole of the swinging balance 51 is inserted into each threading hole of the lifting / lowering balance 52.
In this way, by configuring the thread path so that the needle thread passes from the threading holes of the swinging balance 51 to the threading holes of the lifting / lowering balance 52, the top dead center of each of the swinging balance 51 and the lifting / lowering balance 52. In addition, by appropriately adjusting the phase of the bottom dead center, it is possible to perform any yarn pulling or yarn feeding at any phase by the cooperation of these two balance mechanisms. For example, by adjusting the lifting / lowering balance 52 to be the top dead center at the timing when the swinging balance 51 is at the bottom dead center, the needle thread pulling amount or feeding amount is maximized. By adjusting the lifting / lowering balance 52 so as to be at the top dead center at this timing, it is possible to minimize the amount by which the needle thread is pulled up or fed out.

(Cloth presser)
The cloth presser 44 is supported by the lower end portion of the support bar 44a on the upper side of the needle plate 100, and the support bar 44a is supported so as to be movable up and down inside the sewing machine arm portion 2c. The cloth presser 44 is pressed downward via a support bar 44a by a spring (not shown). When the cloth presser 44 is lowered to the throat plate 100, the workpiece to be sewn on the upper surface of the throat plate 100 can be pressed and held. . Further, the cloth presser 44 is provided with a press-up solenoid 45 (see FIG. 4), which is an actuator for raising and lowering the cloth presser 44 via the support bar 44a, separately from the spring. Thus, the sewing product can be pressed down and held, and the sewing product can be released by the rear stepping operation and released.

(Needle plate)
A plan view of the needle plate 100 is shown in FIG. The needle plate 100 includes a plurality of openings 103 in which feed teeth of a cloth feed mechanism (not shown) are projected and exited, and needle drop holes as insertion parts for the sewing needles 21 and 22 provided at substantially the center of the openings 103. 102 and a cantilever needle plate claw 101 extending toward the downstream side in the cloth feeding direction F between each needle drop hole 102.
Each opening 103 and needle drop hole 102 are formed so as to penetrate the needle plate 100 vertically. A needle plate claw 101 is formed by forming a substantially U-shaped notch so as to connect the two needle drop holes 102. The throat plate claw 101 has a base end portion (lower end portion in FIG. 2) supported by the throat plate 100, and a distal end portion (upper end portion in FIG. 2) is a free end like a cantilever. .
In decorative sewing, the loop of the looper thread L is inserted into the loop of the needle thread T formed by the sewing needles 21 and 22 reaching the lower side of the needle plate 100 from the respective needle drop holes 102, so that Perform seam formation on the side. That is, the looper thread L is sewn along the direction in which the two sewing needles 21 and 22 are arranged. As a result, the looper thread L is in a state straddling the throat plate claw 101 on the lower surface side of the throat plate 100 between the stitch formation and several stitches, and as the sewing progresses, the tip of the throat plate claw 101 is advanced. From the needle plate 100 to the upper surface side.

(Thread feeding mechanism)
FIGS. 3A and 3B are operation explanatory views of the yarn feeding mechanism 60 as viewed from the front. FIG. 3A shows a standby state and FIG. 3B shows a yarn feeding state.
The yarn feeding mechanism 60 includes a lever member 61 provided at one end with a yarn hooking portion 61a that abuts on each needle thread T passing between the yarn lubricating means 41 and the swinging balance 51 from below, and a lever member 61 A support member 62 that is pivotally supported at an intermediate position 61, a thread feeding cylinder 63 that presses the other end of the lever member 61, and a lever member 61 and a swinging balance 51 are disposed between each needle thread T. And a yarn feed amount adjusting unit 65 for individually supporting the yarn guide 66 so that the height thereof can be adjusted.

The lever member 61 is bent at one end to form a thread hook portion 61a, and the thread hook portion 61a can hook the needle threads T from below at the same time. Further, the intermediate portion of the lever member 61 is pivotally supported by a support shaft along the X-axis direction, whereby when the other end portion of the lever member 61 is pressed downward by the yarn feeding cylinder 63, the yarn hooking portion 61a. Can be rotated upward. The lever member 61 is urged by a spring (not shown) so that the other end thereof is always in pressure contact with the plunger side of the yarn take-out cylinder.
The yarn take-out cylinder 63 is a backward-acting air cylinder, and its plunger can be switched between a retracted position shown in FIG. 3 (A) and an advanced position shown in FIG. 3 (B).

The adjustment unit 65 includes three thread guides 66 in preparation for using three needle threads T. However, when only two needle threads T are used, naturally only two thread guides are used. . Each thread guide 66 is held in a state aligned along the X-axis direction by a support base 67, and the support base 67 supports each thread guide 66 so as to be movable in the vertical direction, and its height can be adjusted. It has become. Each thread guide 66 whose height is adjusted is fixed by a set screw (not shown). A threading hole along the Y-axis direction is formed through the upper end of each thread guide 66, and each needle thread T is individually inserted into the threading hole.
In this yarn guide 66, the needle thread T passing from the yarn lubricating means 41 to the yarn guide 66 has a large angle change in the yarn hooking portion 61a due to the change in position of the yarn hooking portion 61a of the lever member 61 from the standby position to the yarn feeding position. In such a case, the amount of thread feeding increases, and when the change in angle is small, the amount of yarn feeding decreases.
For example, in the case of FIG. 3, one thread guide 66 is adjusted to the high position and the other thread guide 66 is adjusted to the low position. In the yarn guide 66 at the high position, the yarn feed amount is small because the angle change at the yarn hooking portion 61a is small. Further, in the low-position yarn guide 66, the yarn feed amount is increased because the angle change at the yarn hooking portion 61a is large.
As described above, the adjustment unit 65 can adjust the thread feeding amount for each needle thread T by the thread feeding mechanism 60 by adjusting the height of each thread guide 66.

(Control means)
FIG. 4 is a block diagram showing a control system of the decorative sewing machine 10.
As shown in the figure, the control means 80 of the decorative sewing machine 10 includes a sewing machine motor 3 that is a driving source for sewing the sewing machine, a press-up solenoid 45 that is a driving source for the vertical movement of the cloth presser 44, and the thread that is described above. The solenoid valve 68 for controlling the operation of the feeding cylinder 63, the operation pedal 4 for operating and inputting the operation at the time of sewing, and each sewing needle are in the upper position (at least the tips of all the sewing needles are above the cloth) An upper position sensor 84 is connected as an upper position detecting means for detecting that the position is more specifically, that is, the top dead center of the sewing needle or a phase that is in the vicinity of the sewing needle. . In practice, the sewing machine motor 3, the press-up solenoid 45, and the solenoid valve 68 are connected to the control means 80 via drive circuits, respectively, but the illustration of each drive circuit is omitted.
The control means 80 includes a ROM 82 storing a control program for realizing operation control during sewing, which will be described later, a CPU 81 executing the control program, and a RAM 83 serving as a work area for each process for executing the control program. It has.

Control executed by the CPU 81 based on the control program will be described.
The aforementioned operation pedal 4 can be stepped forward and stepped back in two steps. When the stepping is performed, the CPU 81 starts the sewing machine motor 3 and at a rotational speed corresponding to the amount of depression of the operating pedal 4. The drive of the motor 4 is executed.
On the other hand, the first step of the operation pedal 4 is assigned an operation instruction for stopping halfway in order to change the sewing direction during sewing, and the second step is an operation instruction at the end of sewing. Assigned.

Here, the operation of changing the sewing direction during sewing by the first step of the operation pedal 4 and the control thereof will be described.
FIG. 5 is an explanatory diagram showing a needle drop position when sewing of decorative stitches is performed with two sewing needles 21 and 22 and the direction of the sewing direction is changed during the sewing. The needle drop position of the sewing needle 21 closer to the outer edge of the workpiece is Toj, and the needle drop position of the inner sewing needle 22 is Tij. J indicates the number of needles to advance (j = 0, 1, 2, 3,...).
As shown in FIG. 5, for example, when the needle drop positions of the sewing needles 21 and 22 from To1, Ti1 to To4, Ti4 up to the corner of the sewing product that needs to be changed in the sewing direction are To4, Sewing is temporarily stopped by the needle entry of Ti4, and the work is rotated 90 ° manually to change the direction. When the resuming position of the sewing is adjusted to the end of the seam, the first needle drop position To5 after resuming the outer sewing needle 21 is in the immediate vicinity of To4, but the first stitching position after resuming the inner sewing needle 22 is first. The needle drop position Ti5 is a position away from Ti4 by the arrow d. That is, when changing the direction of the sewing direction, the needle thread T is hardly consumed for the sewing needle 21, but the needle thread T is consumed for the length d for the sewing needle 22.
Therefore, when such sewing is scheduled, the thread guides 66 and 66 corresponding to the respective sewing needles 21 and 22 of the above-described thread feeding mechanism 60 are set in advance to the amount of thread consumed when the direction is changed. Adjust so that the feeding amount is appropriate. Then, the CPU 81 controls the electromagnetic valve 68 of the yarn feeding cylinder 63 so that the yarn feeding mechanism 60 performs the yarn feeding when the first step of the operation pedal 4 is detected.
Note that the needle drop position immediately after the change of direction when changing the direction of sewing is an example, and is not limited to the positions of To5 and Ti5, but is arbitrary.

  The thread feeding control by the CPU 81 will be described. When the front step of the operation pedal 4 is released and the first step is performed, the CPU 81 stops the sewing machine motor 3 so that the cloth presser 44 is released. At the same time as controlling the press-up solenoid 45, the solenoid valve 68 is controlled so that the plunger of the yarn take-out cylinder 63 protrudes and retracts immediately. Thereby, in a state where the cloth presser 44 is raised, the lever member 61 of the thread feeding mechanism 60 performs an operation of feeding each needle thread T by the set amount and returning to the standby position. At this time, the thread releasing operation of each thread tension of the thread tension mechanism 30 is not executed. As a result, even if the looper yarn L is pulled out from the needle plate claw 101 of the needle plate 100 and the fabric is rotated by 90 °, excess needle yarn is not paid out.

  When the second step of the operation pedal 4 is stepped on, the CPU 81 stops the sewing machine motor 3 and controls the press-up solenoid 45 so that the cloth presser 44 is released. At the same time, the CPU 81 drives the thread tension releasing solenoid 36 of the thread tension mechanism 30 to release all the threads. As a result, the workpiece is released from the cloth presser 44 and each thread is also released, so that the workpiece can be pulled out.

(Description of sewing machine operation)
Hereinafter, operation control during sewing of the decorative sewing machine 10 having the above-described configuration will be described with reference to the flowchart of FIG.
First, the CPU 81 waits for an input of the front pedal of the operation pedal 4 (step S1), and when the front pedal is performed, starts to drive the sewing machine motor 3 (step S2). Then, the sewing machine motor 3 is rotated at a speed corresponding to the depression amount.
Next, the CPU 81 determines input of the first step of the operation pedal 4 (step S3). If there is no input, the process proceeds to step S7. On the other hand, when the first step is detected, control as a midway stop for changing the sewing direction is executed. That is, the drive of the sewing machine motor 3 is stopped (step S4). At this time, the sewing machine motor 3 is stopped by the upper position sensor 84 so that the sewing needle is in the upper position.
Further, the CPU 81 releases the workpiece by operating the press-up solenoid 45 and pulling up the cloth presser 44 (step S5). At the same time, the solenoid valve 68 is controlled to reciprocate the plunger of the yarn take-out cylinder 63 so as to protrude and retreat (step S6). As a result, each needle thread T is fed out from the yarn supply source side by a thread feeding amount corresponding to the adjustment of each thread guide 66 of the adjusting unit 65. In other words, when the workpiece is rotated, the thread is fed out according to the distance to the next needle drop position for each sewing needle 21 and 22. Since this thread feeding operation is performed after the sewing machine is stopped on the sewing machine, each of the balances 51 and 52 has completed the pulling up of the needle thread from the sewing product side. The needle thread is not pulled up, and the thread tensions 31 to 35 of the thread tension mechanism 30 are not released, but the needle thread is fed out from the thread supply source side.
At this time, the operator of the sewing machine performs an operation of pulling out the looper thread from the throat plate claw 101 and changing the direction of the workpiece.

Next, in step S7, the CPU 81 determines the input of the second step of the operation pedal 4, and when there is no input, returns to step S1 and determines the front step again. On the other hand, when the second step is detected, a process for finishing the sewing is executed. That is, the drive of the sewing machine motor 3 is stopped (step S8). At this time, the sewing machine motor 3 is stopped so as to be in the upper position.
Further, the CPU 81 operates the press-up solenoid 45 to lift the cloth presser 44 to release the workpiece (step S9). At the same time, the CPU 81 operates the thread tension release solenoid 36 to set all the thread tensions 31 to 35. Is released (step S10). Thereby, a to-be-sewn material can be removed from the needle plate 100, and sewing is complete | finished.

(Effect of embodiment)
The decorative sewing machine 10 feeds each needle thread T by the thread feeding mechanism 60 when the control means 80 stops sewing by the first step of the operation pedal 4 and when the thread tension mechanism 30 is sewing. Since the state of applying the same thread tension as that of the sewing machine is maintained, it is possible to prevent the extra needle thread T from being fed out by the rotation work of the workpiece and the work for pulling out the looper thread from the needle plate claw 101. It is possible to suppress defects such as a decrease in thread tightening immediately after the direction change, and to improve the sewing quality in decorative sewing.

Further, since the thread feeding mechanism 60 includes an adjustment unit 65 and can individually adjust the feeding amount of each needle thread, the amount of change in the needle drop position of each sewing needle 21, 22 in the direction change operation of the sewing product. And the needle thread feed amount are set equal to each other, the minimum necessary thread feed required for the direction change work of the sewing product can be performed. It becomes possible to further improve the sewing quality in the sewing.
In addition, since the cloth presser is switched to the released state in conjunction with the feeding of each needle thread T, it is possible to easily perform the rotation operation of the sewing product, and the operability is improved.

(Other)
It should be noted that the thread tension releasing solenoid 36 may be controlled so that the thread is released when the thread is being fed by the thread feeding mechanism 60 of the decorative sewing machine 10 (only while the thread feeding cylinder 68 is being driven). Further, an actuator capable of controlling the thread tension may be mounted on each of the thread tensions 31 to 35, and control may be performed so that the thread tension is reduced more than that during sewing only when the thread is fed.

  The thread tension mechanism 30 may be a manual release type instead of an actuator. In that case, the rear stepping of the operation pedal 4 is set to only one stage, and it is not distinguished between the temporary stop of sewing and the stop due to the end of sewing. May be performed. In this case, the thread feeding is performed even at the end of the sewing, but since the sewing object is removed by the end of the sewing, there is no influence on the sewing quality or the next sewing operation.

  Further, the number of sewing needles is not limited to two and may be more. For example, when three needles are used, the needle holder 44a may be replaced with one that can hold three sewing needles, and the needle plate 100 may be replaced with one having two needle plate claws 101 formed thereon. In other words, a needle plate in which a substantially W-shaped notch is formed instead of a substantially U-shaped notch is used.

10 Decorative Sewing Machines 21 and 22 Sewing Needle 30 Thread Tension Mechanism 36 Thread Tension Release Solenoid (Actuator)
44 Cloth presser 45 Presser lifting solenoid (actuator)
51 Oscillating balance 52 Lifting balance 60 Thread feeding mechanism 65 Adjustment unit 80 Control means 100 Needle plate 101 Needle plate claw 102 Needle drop hole (insertion portion)

Claims (5)

A needle up-and-down movement mechanism for moving up and down a plurality of sewing needles arranged along the direction intersecting the cloth feeding direction;
A balance for pulling up the needle thread of each sewing needle; and an upper position detecting means for stopping each sewing needle at a position above the cloth;
A cloth presser that can hold the sewing product at the time of sewing and release the sewing product by raising it,
A needle plate having a cantilever needle plate claw extending toward the downstream side in the cloth feeding direction between the insertion portion of each sewing needle and the insertion portion;
A thread tension mechanism that individually applies thread tension to the needle thread of each sewing needle;
In a decorative sewing machine comprising
Provided in the course of the needle thread path from the thread tension mechanism to each of the sewing needles, and individually for each of the needle threads in order to feed the thread according to the amount of rotation of the sewing product for changing the sewing direction. A yarn feed mechanism that can be adjusted to each yarn feed amount,
A decorative sewing machine comprising: control means for feeding each needle thread by the thread feeding mechanism when the sewing needle is stopped by detection by the upper position detecting means.   The yarn feeding mechanism includes an adjusting unit for individually adjusting the feeding amount of each needle thread so that the feeding amount of the outer needle thread is larger than the feeding amount of the needle thread inside the cloth rotation corner portion. The decorative sewing machine according to claim 1, wherein the sewing machine is a sewing machine. An actuator for switching the cloth presser to a released state;
The decorative sewing according to claim 1 or 2, wherein the control means controls the actuator to switch the cloth presser to a released state in conjunction with the feeding of each needle thread by the thread feeding mechanism. sewing machine. The thread tension mechanism includes an actuator that switches to a released state that does not apply thread tension,
The control means controls the actuator to maintain the thread tension mechanism in a non-released state with respect to the actuator at least after each needle thread is fed by the thread feeding mechanism while the sewing is stopped. The decorative sewing machine according to any one of claims 1 to 3.   5. The decorative sewing machine according to claim 4, wherein the control means reduces the thread tension of the thread tension mechanism during sewing of each needle thread by the thread feeding mechanism as compared with sewing.

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