JP6502699B2 - sewing machine - Google Patents

Description

  The present invention relates to a sewing machine provided with a middle presser.

In the stitch formed by the sewing machine, the upper thread and the lower thread are formed in a state in which the upper thread and the lower thread are tangled with each other (see FIG. 27A) and only the upper thread draws a spiral. There is a formed hitch stitch (see FIG. 27 (B)). Perfect Stitching allows the tension of the upper thread and the tension of the lower thread to act on the fabric in a well-balanced manner, resulting in a good finish, and can provide a high quality sewing product. On the other hand, in the case of the hitch stitch, the tension of the upper thread tends to be weak, the balance of the tension of the lower thread is poor, the adverse effect such as loosening of the seam is likely to occur, and the sewing quality tends to deteriorate.
One of the causes of the occurrence of the above-mentioned hitch stitch is whether the upper thread passing from the sewing needle to the cloth at the time of needle dropping becomes clockwise or counterclockwise with respect to the sewing needle.

The electronic cycle sewing machine performs sewing with a desired sewing pattern by holding the cloth with the cloth presser and moving the cloth in an arbitrary direction according to the sewing pattern data, the cloth in all directions of 360 ° around the sewing needle Depending on the direction of movement of the fabric, hitch stitching may occur.
Therefore, the conventional electronic cycle sewing machine is provided with a needle bar turning mechanism, stores in advance the angle range in the direction in which the hitch stitch can occur, and the movement direction of the fabric can generate the hitch stitch every time the needle falls It is determined whether it belongs to the angle range, and if it belongs to the angle range, the needle bar is rotated before the sewing needle pierces the cloth, and the motion control is performed so as to get out of the angle range where the hitch stitch can occur. (See, for example, Patent Document 1).

JP, 2012-213603, A

In the above-mentioned conventional electronic cycle sewing machine, when the needle bar is rotated, it is desirable that the rotation of the needle bar be completed just before the tip of the sewing needle reaches the cloth, and if the rotation is too fast The positional relationship with the upper thread is broken, and if it is too late, the sewing needle is stuck in the fabric before the rotation is completed, so that the effect of suppressing the occurrence of the hitch stitch is reduced.
However, since the rotation of the needle bar is performed at a constant operation timing, there is a problem that when the thickness of the fabric changes, the rotation of the needle bar can not be performed at an appropriate timing. Therefore, there is a possibility that the hitch stitch can not be sufficiently suppressed.

  An object of the present invention is to effectively suppress the occurrence of hitch stitches.

The invention according to claim 1 is
A needle bar that holds a sewing needle and moves up and down,
A hook for winding the upper thread to the lower thread by a pivoting operation;
A sewing machine motor serving as a driving source of vertical movement of the needle bar;
A needle bar turning mechanism for turning the needle bar around a center line along its longitudinal direction;
A movement mechanism for moving the sewing material along a horizontal plane in an arbitrary movement direction by the cloth holding unit to cause needle dropping at an arbitrary position;
A control unit that controls the moving mechanism based on sewing data that defines a needle drop position for each needle or a movement amount of the sewing material for each needle for forming a predetermined sewing pattern;
A middle presser which is juxtaposed to the sewing needle and prevents lifting of the material to be sewn held by the cloth holding unit;
A middle presser elevating mechanism including an actuator for moving the middle presser up and down in synchronization with the needle bar and changing and adjusting the bottom dead center height of the middle presser;
The needle bar is moved by the needle bar turning mechanism from the forward path and the return path when the control unit belongs to an angle range in which the movement direction of the sewn material determined in the sewing data is generated by a predetermined hitch stitch. In a sewing machine that performs control so as to perform the reciprocal reciprocating movement
The control unit controls an actuator of the middle presser-lifting mechanism so that the lower dead center height of the middle presser becomes a preset set value, and the set value of the lower dead center height of the middle presser From the above, the drive start timing of the needle bar turning mechanism is calculated using the fact that the bottom dead center height of the inner presser matches the thickness of the sewing material, and the tip of the sewing needle is made of cloth The needle bar turning mechanism is controlled such that the forward movement of the needle bar is completed before reaching the needle bar.

The invention according to claim 2 is the sewing machine according to claim 1
The lower side of the needle plate is provided with a yarn moving mechanism for moving the lower yarn by a yarn moving member,
The control unit
When the moving direction of the sewing material for each needle drop by the moving mechanism is a predetermined first angle range, thread shifting by the thread shifting mechanism is executed;
When the movement direction is a predetermined second angle range, rotation of the needle bar by the needle bar rotation mechanism is performed.

The invention according to claim 3 is the sewing machine according to claim 1 or 2
A setting input unit for setting a setting value of the bottom dead center height of the middle presser may be provided.

The invention according to claim 4 is the sewing machine according to any one of claims 1 to 3 in which
The set value of the bottom dead center height of the middle presser per needle is set in the sewing data,
The control unit controls an actuator of the middle pressing and lowering mechanism and the needle bar turning mechanism for each needle.

  In the present invention, the needle bar rotating mechanism is configured such that the forward path rotation ends when the tip of the sewing needle reaches the set value of the bottom dead center height of the middle presser that presses the behavior of the sewing material from above Since it is controlled, it is possible to end the forward rotation of the needle bar in accordance with the timing at which the lower end of the sewing needle reaches the upper surface of the pressed workpiece. For this reason, it is necessary to suppress occurrence of situations such as completion of rotation of the forward path at a position where the sewing needle is separated above the workpiece, or termination of rotation of the forward path after the sewing needle pierces the workpiece. Since the needle bar rotation is performed at an appropriate timing, the hitch stitch can be suppressed more effectively.

It is a perspective view of a sewing machine of an embodiment of the invention. It is a perspective view which shows the state which notched a part of front end part of a sewing machine arm part. It is a perspective view of a needle stick stand. It is a perspective view of the upper end part of a needle stick stand. It is a perspective view of the lower end part of a needle stick stand. It is a perspective view which shows the structure of the connection part of a crank rod and a needle bar. It is a perspective view different from FIG. 6 which shows the structure of the connection part of a crank rod and a needle bar. It is a perspective view of an operation system of a needle bar rotation mechanism. It is a top view of the operation system of a needle bar rotation mechanism. FIG. 10 (A) is an enlarged perspective view of the upper end portion of the needle bar stand of the needle bar turning mechanism, and FIG. 10 (B) is an exploded perspective view. It is a top view of the needle bar cam member of a needle bar rotation mechanism. It is a top view of threading mechanism. It is a perspective view of a threading mechanism. It is a sectional view of a thread tension device. It is a schematic block diagram of a middle pressing up-and-down movement mechanism, and Drawing 15 (A) shows the state which made middle pressing a low position, and Drawing 15 (B) makes middle pressing a high position. It is a block diagram showing a control system of a sewing machine. FIG. 17 (A) is a cross-sectional view showing a state in which the upper thread passing through the eye hole is entangled in the left-handed direction when the sewing needle is stuck in the cloth, and FIG. 17 (B) is a state where the upper thread is entangled in the right-handed direction It is a sectional view showing. FIG. 18 (A) is a plan view showing the lower thread extending from the corner portion of the bobbin case of the hook to the needle hole of the needle plate, and FIG. 18 (B) is a front view thereof. It is explanatory drawing which shows the relationship between the movement direction of cloth, and the generation | occurrence | production factor of a hitch stitch in the sewing machine using a half-turn hook. It is explanatory drawing which shows the table data which memorize | stored which of thread | yarn shifting and needle-bar rotation should be performed according to the angle division of the cloth feed direction. It is a diagram which shows the relationship between an upper axis angle and the height of a sewing needle. It is a motion diagram of a sewing needle, a hook, and a balance in a sewing machine. It is a top view which shows the positional relationship of the threading member and the needle hole in the state which is not performing threading. It is a top view which shows the positional relationship of the thread | yarn shifting member and needle hole in the state which is performing thread | yarn shifting. It is explanatory drawing which shows the withdrawal condition of the lower thread at the time of execution of thread shifting. It is a flowchart of hitch stitch avoidance control. FIG. 27A shows a perfect stitch, and FIG. 27B shows a hitch stitch.

Summary of the Embodiments of the Invention
An embodiment of the present invention will be described based on FIGS.
The sewing machine 100 described below as the present embodiment is a so-called electronic cycle sewing machine, which moves the cloth by a holding frame as a cloth holding portion for holding a cloth which is a sewn material to be sewn and drops the needle to an arbitrary position The movement mechanism is configured to make it possible to form a sewing pattern based on predetermined sewing data on the cloth held by the holding frame.
Further, in the sewing machine 100, depending on the direction of movement of the cloth by the holding frame, it is possible to selectively implement the thread shifting of the lower thread or the rotation of the needle bar to prevent the occurrence of the hitch stitch.

FIG. 1 is a perspective view of a sewing machine 100 according to the present invention.
Here, the direction in which the sewing needle 11 described later moves up and down is taken as the Z-axis direction or the up-down direction, one direction orthogonal to this is taken as the X-axis direction or the left-right direction, and is orthogonal to both the Z-axis direction and the X-axis direction Is defined as the Y-axis direction or the front-rear direction. In the following description, “front” is a direction in which an operator who performs sewing with respect to the sewing machine 100 is located, “left” is a left hand side in a state where the operator at the front side of the sewing machine 100 faces the sewing machine 100 “Right” indicates the right side in a state in which the operator on the front side of the sewing machine 100 faces the sewing machine 100.

  The sewing machine 100 holds a needle 11 at its lower end and moves up and down along the Z-axis direction, and a needle vertical movement mechanism 20 which moves the needle vertically using a sewing machine motor 21 as a drive source. A needle bar turning mechanism 30 for turning the needle bar 12 around its center line along the Z-axis direction, a hook 13 for winding the lower thread on the upper thread passed through the sewing needle 11 by the lowering operation, and the lower thread A yarn moving mechanism 50 for moving the yarn, a yarn tensioning device 70 for variably adjusting the yarn tension of the upper yarn, and a cloth as a moving mechanism for holding the cloth and arbitrarily moving and positioning along the XY plane A moving mechanism 80, a control unit 90 as a control unit for controlling the operation of each of the above-described components, and a middle presser 110 for suppressing the flapping of the fabric held by the holding frame 81 as the cloth holding unit of the cloth moving mechanism 80. And (see Figure 15), move the middle presser 110 up and down A vertical movement mechanism 120 retainer in which (see FIG. 15), and a sewing machine frame 101 for supporting the respective components of the sewing machine 100 mainly comprises.

Sewing machine frame
As shown in FIG. 1, the sewing machine 100 includes a sewing machine frame 101 whose outer shape is substantially U-shaped when viewed from the X-axis direction. The sewing machine frame 101 includes a sewing machine arm 101a forming an upper portion of the sewing machine 100 and extending in the Y-axis direction, a sewing machine bed 101b forming a lower portion of the sewing machine 100 and extending in the Y-axis direction, a sewing machine arm 101a and a sewing machine bed 101b And a standing barrel 101c connecting the two.

Needle up and down movement mechanism
FIG. 2 is a perspective view showing a state in which a part of the front end portion of the sewing machine arm portion 101a is cut away.
As shown in FIG. 1 and FIG. 2, the needle up-and-down movement mechanism 20 is supported by the upper shaft 22 rotatably supported in a state along the Y-axis direction in the sewing machine arm portion 101a and one end of the upper shaft 22 The sewing machine motor 21 shown in FIG. 16 for applying a rotational force, the needle bar crank 23 provided at the other end of the upper shaft 22, and the crank rod having one end connected at an eccentric position with respect to the rotational center of the needle bar crank 23. And a guide 25 for guiding the end of the crank rod 24 on the needle bar 12 side to reciprocate in the vertical direction.
The upper shaft 22 is directly connected to the output shaft of the sewing machine motor 21 and is rotationally driven. The rotation of the upper shaft 22 is converted into vertical reciprocating motion by the needle bar crank 23 and the crank rod 24 and transmitted to the needle bar 12 Ru.

A support shaft 26 extending in the Y-axis direction is penetrated at an end of the crank rod 24 on the needle bar 12 side, and the support shaft 26 sandwiches the crank rod 24 at both ends thereof so as to hold two square pieces 27 and 28 It is pivotally supported rotatably.
The square piece 27 provided on the surface of the crank rod 24 on the side of the needle bar 12 engages with the needle bar 12 via needle bar clamps 331 and 332 (see FIG. 6) described later, and the needle bar 12 Transmit vertical movement to Further, a square piece 28 provided on the surface opposite to the needle rod 12 with respect to the crank rod 24 is fitted in a groove-shaped guide 25 formed along the Z-axis direction on the wall surface of the sewing machine arm portion 101a. ing. That is, since the square piece 28 is fitted in the groove-like guide 25 in a slidable manner, the end of the crank rod 24 on the needle bar 12 side is restricted in movement in the X-axis direction while restricting movement in the X-axis direction. It is possible to reciprocate only along.
As a result, the needle bar 12 is given a reciprocating motion in the vertical direction in synchronization with the rotation of the sewing machine motor 21.

[Kam]
The sewing machine 100 according to the present embodiment exemplifies a case where a semi-rotary hook is employed as the hook. The semi-rotary hook gives reciprocating movement to the middle hook which reciprocates in synchronization with the vertical movement of the needle bar 12 inside the main hook, the bobbin and bobbin case housed inside the middle hook, and the middle hook Driver, a crank rod whose one end is connected to the crank formed on the upper shaft 22, a reciprocation rotation shaft having an arm portion connected to the other end of the crank rod, and a reciprocation rotation shaft. And a lower shaft that is reciprocated and rotated at high speed, and the lower shaft is configured to reciprocate and rotate the hook through a driver. The above-mentioned sewing machine motor 21 serves as a driving source of the up and down movement of the needle bar 12 and the rotational movement of the hook 13. The inner hook reciprocates in a cycle of 1/2 of the upper shaft 22. The upper thread is entangled with the lower thread by the movement and the rotation of the hook 13. In addition, since the structure and structure of a half-turn kettle are known, detailed description is abbreviate | omitted.

[Needle bar rotating mechanism]
Needle bar rotating mechanism 30 is rotatably supported at the front end portion of sewing machine arm portion 101a around Z axis (also referred to as vertical axis) and supports needle bar 12 so as to be able to move needle bar 12 up and down. And, an operation system for giving a rotational movement around the Z axis to the needle bar 12 through the needle bar stand 31 is mainly configured.
FIG. 3 is a perspective view of the needle bar base 31, FIG. 4 is a perspective view showing an upper end thereof, and FIG. 5 is a perspective view showing a lower end thereof.

  The needle bar base 31 is formed in a cylindrical shape in which the upper end portion 311 and the lower end portion 312 are concentric with each other, and they are integrally connected by a rectangular frame portion 313. Then, cylindrical metal bearings 321 and 322 are held inside the lower end portion 312 and the frame portion 313, and the round bar-like needle bar 12 is inserted inside these two metal bearings 321 and 322. Thus, the needle bar 12 is vertically movably supported along the Z-axis direction.

Further, bearings 323 and 324 are respectively provided on the outer circumferences of the upper end portion 311 and the lower end portion 312 of the needle bar base 31, and the outer circumferences of the respective bearings 323 and 324 are held by the wall surface of the sewing machine arm portion 101a. As a result, the needle bar base 31 and the needle bar 12 supported by the needle bar base 31 are rotatable around the Z axis with respect to the sewing machine arm portion 101a.
Reference numerals 325 and 326 denote washers, respectively, for holding the sliding property of the bearings 323 and 324 between the outer ring and the needle bar base 31 side.

  Further, the frame portion 313 of the needle bar base 31 includes a rectangular flat portion along the Z-axis direction, and a detection body 328 is fixedly mounted on the upper portion of the flat portion. The proximity state of the detection body 328 is detected by a needle bar angle sensor 329 which is a proximity sensor provided on the wall surface of the sewing machine arm portion 101a. That is, the needle bar angle sensor 329 outputs a detection signal according to the distance from the detection body 328, and thereby, the proximity state or separation state of the detection body 328 with respect to the needle bar angle sensor 329 can be identified. When the closest state is defined as the origin position in the rotational direction of the needle bar 12, it is possible to identify whether the needle bar 12 is at the origin or whether it is rotating away from the origin.

Further, a long guide plate 330 is screwed on the flat portion of the frame portion 313 of the needle bar base 31. The guide plate 330 is formed with a slit 330 a in a state of penetrating the front and back along the Z-axis direction. Although the plane portion of the frame portion 313 is not shown, the back side of the guide plate 330 has an opening larger than the slit 330 a of the guide plate 330.
The needle bar 12 is fixedly equipped with a needle bar clamp 331 shown in FIGS. 6 and 7 described later, and the needle bar clamp 331 extends outward in the radial direction centering on the needle bar 12 A rectangular projection 331a is formed. The projection 331a is inserted into the slit 330a from the back side of the guide plate 330 to the outside, and when the needle bar 12 moves up and down, the projection 331a moves up and down in the slit 330a. The lateral width of the projection 331a is set to be substantially equal to the width of the slit 330a, so that when the needle bar base 31 rotates about the Z axis, the needle bar 12 also rotates in unison. ing.

6 is a perspective view showing the structure of the connecting portion between the crank rod 24 and the needle bar 12, and FIG. 7 is a perspective view different from FIG. 6 showing the structure of the connecting portion between the crank rod 24 and the needle bar 12.
As described above, a corner piece 27 is pivotally supported around the Y axis on the lower end portion of the crank rod 24 and on the surface on the needle bar 12 side.
Then, two needle bar clamps 331 and 332 are vertically aligned and fixed to the needle bar 12 with a predetermined gap. Then, between the needle bar holding members 331 and the needle bar holding members 332 lined up and down, a square piece 27 is interposed via washers 333 and 334.
The washers 333 and 334 are formed of a material having good slidability, and the sliding surface of the square top 27 is excellent in slidability. Further, in each washer 333 and 334, a pin protrudingly fitted to each needle bar clamp 331 and 332 is engaged, and when the needle bar 12 is rotated, the needle bar clamp 331 and 332 performs a pivoting operation. It is supposed to be.
Further, as described above, the upper needle bar clamp 331 is provided with a protrusion 331 a on the front side in the Y-axis direction, along the guide plate 330 and the needle bar base 31 around the Z axis. Rotate. At that time, each needle bar holder 331, 332 rotates with the needle bar 12, but the corner piece 27 supported by the crank rod 24 is positioned between the needle bar holders 331, 332 via the washers 333 and 334. It is possible to maintain the above state and transmit power of vertical movement from the sewing machine motor 21 to the needle bar 12 even when the needle bar is rotating.

FIG. 8 is a perspective view of an operation system of the needle bar turning mechanism 30, FIG. 9 is a plan view, and FIG. 10 is an enlarged perspective view.
The operation system of the needle bar turning mechanism 30 includes a needle bar turning motor 34 (see FIG. 16) as a driving source, a needle bar cam member 35 operated by the needle bar turning motor 34, and a needle bar cam member 35. It mainly includes a boss-like portion 36 as a driven body to which movement is applied, and a transmission member for transmitting a pivoting motion from the boss-like portion 36 to the needle bar 12. The transmission member mainly includes a cam arm 361 and an arm member 327.

The needle bar turning motor 34 is supported by a motor mount 341 attached to the left side surface of the sewing machine arm portion 101a with its output shaft directed vertically upward, as shown in FIGS. The output sprocket is equipped with a main sprocket 342. A small-diameter driven sprocket 343 is provided adjacent to the main driving sprocket 342 on the upper surface of the motor mount 341, and the timing belt 344 is stretched over the sprockets 342 and 343. Speeding up rotation is transmitted to.
The driven sprocket 343 is connected to the needle bar cam member 35 via the rotation shaft 345, and the rotation of the driven sprocket 343 is transmitted to the needle bar cam member 35.

FIG. 11 is a plan view of the needle bar cam member 35. As shown in FIG. The needle bar cam member 35 is a disk-shaped grooved cam, and on the lower surface thereof, a cam groove 351 is formed which is a groove whose depth direction is the vertical direction.
The cam groove 351 is formed in an endless annular shape, in which five operation sections 352 for applying a reciprocating motion of one reciprocation to the needle bar base 31 are continuous. That is, in the needle bar cam member 35, one operation section 352 is formed in the range of an angle of 72 °.
Then, the displacement of one motion segment 352 gradually increases with the minimum displacement position at which the distance is the smallest from the rotation center as the starting point 352a, and the displacement is the maximum at the midpoint 352b of the segment. The displacement is gradually reduced until it reaches the starting point 352a.

  Further, before and after the starting point 352a, there is provided an approach section in which the distance is constant in the radial direction. The needle bar turning motor 34 has an operation characteristic of rising at a low speed immediately after the start of driving, gradually reaching a high speed, decreasing the speed to a low speed again and stopping. For this reason, in order to properly perform the needle bar turning operation requiring high speed, the needle groove turning motor 34 starts rising at a low speed in the cam groove 351 of the needle bar cam member 35 (immediately after the starting point 352a) An approach section (section in which displacement in the radial direction does not occur) is provided in the section immediately before the stop (immediately before the starting point 352a) so as not to contribute to the needle bar turning operation. In addition, since the timing of the needle bar turning operation is required to be rigid, it is necessary to quickly start the driving of the needle bar turning motor 34 by the length of the approach section.

In the needle bar cam member 35, when the needle bar 12 is not rotated, the boss 36 of the cam arm 361 is located at the starting point 352a, and the boss 36 extends from there to the starting point 352a of the next movement section 352. The needle bar cam member 35 is rotationally driven to move, so that the needle bar base 31 reciprocates and pivots through the cam arm 361.
At this time, since the needle bar cam member 35 is a grooved cam, the boss portion 36 is prevented from being deviated from the needle bar cam member 35 by centrifugal force even when rotating at a high speed, which is stable. Operation is maintained.

Further, in the needle bar cam member 35, the cam groove 351 is an endless annular cam, so that the needle bar rotary motor 34 is rotationally driven in a fixed direction in order for the needle bar base 31 to reciprocate. For example, as compared with the case where the needle bar turning motor 34 is switched between forward and reverse rotation in the forward pass and the backward pass of the reciprocal rotation of the needle bar base 31, the smooth operation is not affected by the inertial force. As a result, it is possible to reciprocate the needle bar base 31 at a higher speed.
Furthermore, since the needle bar cam member 35 has the plurality of operation sections 352 continuously formed without breaks, the needle bar cam member 35 is operated when it is necessary to perform the needle bar turning operation for a plurality of continuous needles. There is no need to intermittently drive each section 352, and it is possible to rotate the needle bar a plurality of times by rotating continuously. Therefore, unlike in the case of intermittent rotation in which rotation stops repeatedly during continuous rotation, it is not necessary to rapidly accelerate from the stopped state to the high speed state, and stable continuous rotation is possible.

Further, as described above, since the cam groove 351 of the needle bar cam member 35 is the entire circumference cam, the durability of the timing belt 344 for transmitting the rotational operation from the needle bar turning motor 34 to the needle bar cam member 35 is improved. It is possible.
Not only the timing belt but also the needle bar cam member 35 can be operated by a gear. Even in that case, it is possible to improve the durability of the gear as well.

Further, in the needle bar turning mechanism 30, an origin sensor 355 is juxtaposed to the needle bar turning motor 34. That is, a detector 346 is mounted on the output shaft of the needle bar rotation motor 34, and the origin sensor 355 detects the presence or absence of the detector 346, whereby the origin position of the needle bar rotation motor 34 is detected. The controller 90 can recognize the starting point 352 a of each operation section 352 of the needle bar cam member 35 by counting the number of pulses from the origin position of the needle bar turning motor 34.
Therefore, the origin sensor 355 detects the detector 346 and positions the boss 36 at the reference standby position in the cam groove 351 of the needle bar cam member 35 (the boss 36 is positioned at the origin 352a). be able to. That is, by rotating the needle bar cam member 35 from the state where the boss portion 36 is positioned at the reference standby position, the intermediate point 352b is maximally displaced with the needle bar turning motor 34 reaching high speed. It is possible to reach it and to perform needle rotation at high speed.

The boss 36 is in contact with the upper surface of the upper end of the rotating end of one arm 361 a of the cam arm 361 as a transmission member that is a bell crank, and the other arm of the cam arm 361 is The portion 361 b is connected to the rotating end of the arm member 327 via the corner piece 362.
Further, the cam arm 361 can be rotated via a support shaft along the Z-axis direction to a motor mount 341 in which the base end sides of the two arm portions 361a and 361b are fixed to the wall surface of the sewing machine arm portion 101a. It is supported by

As shown in FIG. 10, an arm 361b on the needle bar base 31 side of the cam arm 361 has a support shaft 362a pivotally supporting a square top 362 about the Z axis. The square top 362 is a rectangular parallelepiped in plan view, and is fitted in a guide groove 327a as a groove having a width equal to the width of one side of the square top 362 formed on the arm member 327.
The link mechanism that transmits the pivoting motion from the boss 36 (follower) to the needle bar 12 via the needle bar base 31 includes a cam arm (link body) 361, a support shaft 362a, and an angular piece (sliding member) And 362, an arm member 327.

The square top 362 (sliding member) is slidable along the guide groove 327a and is connected to the guide groove 327a so as not to be restrained in the vertical direction. In addition, although the square top 362 is pivotally supported by a support shaft 362a along the vertical direction, a predetermined amount of clearance is formed so as not to contact the lower surface of the arm 361b.
Further, the guide groove 327a is formed in a horizontal plane on the rotating end side of the arm member 327. When the guide groove is formed so that the center line of the guide groove 327a passes through the rotation center of the needle bar stand 31, the rotation of the needle bar stand 31 becomes smooth. That is, the guide groove 327 a is formed along the radial direction centering on the needle bar 12.
The arm member 327 is clamped and fixed to the upper end portion 311 of the needle bar base 31. Thus, when the cam arm 361 performs a turning operation, the rotation is transmitted to the needle bar base 31 through the arm member 327.
At this time, the angular pieces 362 slide along the guide grooves 327 a of the arm members 327 to maintain the connection between the cam arms 361 and the arm members 327.
In addition, when these pivoting operations are performed at high speed, if the space between the cam arm 361 and the arm member 327 is restrained in the vertical direction, vibration, noise, noise, etc. may occur due to the sliding between the members. Since the top 362 is not constrained in the vertical direction with respect to the guide groove 327a, the cause is eliminated and noise can be reduced.

A thrust receiver 335 is fixed to the upper end portion 311 of the needle bar base 31 immediately above the arm member 327. The thrust receiver 335 is held in contact with the bearing 323 via the washer 325 and fixed to the upper end portion 311 of the needle bar base 31 to prevent rattling of the needle bar base 31 relative to the washer 325 in the vertical movement direction. It is a thing.
As described above, since the thrust receiver 335 and the arm member 327 are separate members, the position adjustment of the arm member 327 relative to the cam arm 361 can be performed as compared with the case where they are integrated. Yes, this also prevents the generation of noise.

[Yellow alignment mechanism]
FIG. 12 is a plan view of the thread shifting mechanism 50, and FIG. 13 is a perspective view.
The thread shifting mechanism 50 is provided inside the sewing machine bed portion 101 b and below the needle plate 14, and performs thread shifting of the lower thread by the thread shifting member 51. The yarn transfer mechanism 50 moves a lower thread extending from the bobbin case to the needle hole 15 of the needle plate 14 and changes its path, and a yarn serving as a drive source for the yarn transfer operation of the thread transfer member 51. Yarn motor 52, yarn moving cam member 53 operated by yarn moving motor 52, boss-like portion 54 as a driven member to which operation is given from yarn moving cam member 53, yarn moving member from boss-like portion 54 It mainly comprises a link mechanism 55 for transmitting the yarn shifting operation of the lower yarn to the wheel 51. The link mechanism 55 mainly includes a boss arm 541 and a support shaft 542.

The thread shifting motor 52 is supported by a motor mount 521 mounted on the inside of the sewing machine bed portion 101b with its output shaft directed vertically upward, and the output shaft is equipped with a main movement gear 522 There is. A small diameter driven gear (not shown) is provided adjacent to the main driving gear 522 on the top surface of the motor mount 521, and they are meshed with each other to accelerate rotation from the main driving gear 522 to the driven gear. It is supposed to be transmitted.
The driven gear is connected to the threading cam member 53 via the rotation shaft 524, and the rotation of the driven gear is transmitted to the threading cam member 53.

Like the needle bar cam member 35 of the needle bar turning mechanism 30 described above, the yarn transfer cam member 53 is a disk-shaped groove cam, and on the lower surface thereof, the cam having a groove whose depth direction is the vertical direction. The groove 531 is formed.
The cam groove 531 is formed in an endless annular shape, in which five operation sections for applying a pivoting operation for one reciprocation to the thread shift member 51 are continuous. Each motion section has a shape that reaches the starting point (minimum displacement position) of the next motion section via the middle point (maximum displacement position) with the largest distance from the minimum displacement position with the smallest distance from the rotation center It is formed in a shape which is gradually displaced as a whole.
When the boss 54 is located at the starting point (minimum displacement position), the tip of the thread shifting member 51 is at the standby position in front of the needle hole 15, and the boss 54 moves to the middle point (maximum displacement position) The thread shifting member 51 passes under the needle hole 15 and moves to a predetermined stop position behind the needle hole 15. Then, when the boss portion 54 moves to the next starting point, the tip end of the thread shifting member 51 passes immediately below the needle hole 15 and returns to the standby position in front of the needle hole 15.

Further, in the cam groove 531 of the threading cam member 53, on the intermediate point side adjacent to the starting point, a run-in section in which the distance is constant in the radial direction is provided. Also, an approach section is provided adjacent to the intermediate point and on the side of the starting point of which the distance is invariant in the radial direction.
When performing threading of the lower thread, the yarn transfer member 51 passes from the above-described standby position directly below the needle hole to move to the stop position, and once stops, returns to the standby position.
Therefore, since there is an approach section for each of the case where the boss 54 moves from the start point to the middle point and the case where the boss 54 moves from the middle point to the start point, the forward movement of the threading motor 52 and When rotating on the return path, it is possible to use only the high speed range of the thread shifting motor 52 in any case.
Further, since the threading cam member 53 is also a full circumferential cam whose cam groove 531 is an endless ring, the threading member 51 can be rotated smoothly and at high speed without being affected by the inertia force.

  Although the threading cam member 53 does not show an origin sensor like the needle bar cam member 35 described above, the boss shaped portion 54 is also used as the starting point of the cam groove 531 in the threading mechanism 50. An origin sensor for detecting the position state is provided, and rotation is started from a state in which the yarn shifting cam member 53 is in the standby position, and the yarn shifting cam member 53 is rotated when the yarn lifting motor 52 is just in high speed. It may be configured to perform an operation.

The boss 54 inserted into the cam groove 531 of the threading cam member 53 is pivotally supported by one arm 541 a of a boss arm 541 which is a bell crank, and is attached to the other arm 541 b of the boss arm 541. The yarn transfer member 51 is held.
The boss arms 541 are rotatably supported by pivots 542 provided on the motor mount 521 at the base end sides of the two arms 541 a and 541 b.

  The proximal end of the yarn transfer member 51 is held by the rotating end of the arm 541 b of the boss arm 541, and the distal end of the yarn transfer member 51 is in the direction of the needle hole 15 below the needle plate 14. It has been extended to Further, the tip end side of the thread shift member 51 is a free end, and the tip end is formed in a sharp shape. The tip end portion of the thread shifting member 51 normally separates forward with respect to the needle hole 15 and stands by at the standby position, and the tip end portion passes just below the needle hole 15 at the time of thread positioning. Then, the bobbin thread is moved to the specified stop position, and the lower thread extending from the bobbin case to the needle hole 15 is hooked and moved backward.

  Further, on the left side of the needle plate 14, there is provided a guide 511 for supporting the plate-like threading member 51 so as to interpose before and after the rotation operation in the gap between the two upper and lower plate members. The vertical movement of the thread shift member 51 is suppressed.

With the above configuration, in the yarn shifting mechanism 50, the yarn lifting motor 52 is driven in a fixed direction (for example, clockwise) from the state where the boss portion 54 is positioned at the starting point of the cam groove 531 of the yarn shifting cam member 53. When it starts, the yarn shifting cam member 53 is rotated to the stop position in the high speed region through the approach section. As a result, the tip end portion of the thread shift member 51 passes under the needle hole 15 and pulls the lower thread backward.
When the yarn shifting motor 52 resumes driving in a fixed direction (for example, clockwise) after the yarn shifting member 51 is temporarily stopped at the stop position, the boss portion 54 is the maximum of the cam groove 531 of the yarn shifting cam member 53. From the position to be displaced, it moves to the starting point (minimum displacement position) of the next operation section in the high speed area through the entry section, and the threading member 51 is pivoted to the standby position side. As a result, the tip end of the thread shift member 51 passes just below the needle hole 15 and separates from the lower thread, and retracts to the standby position.

Cloth Movement Mechanism
As shown in FIG. 1, the cloth moving mechanism (moving mechanism) 80 has a holding frame (cloth holding portion) 81 for holding the cloth on the upper surface of the sewing machine bed portion 101b and a support arm 82 for supporting the holding frame 81 so as to be able to move up and down. The X-axis motor 83 shown in FIG. 16 moves the holding frame 81 in the X-axis direction via the support arm 82, and the Y-axis shown in FIG. 16 moves the holding frame 81 in the Y-axis direction via the support arm 82. A motor 84 is provided. The holding frame 81, which is also referred to as a cloth holding portion, includes a lower plate, not shown, which is a rectangular frame, and a cloth pressing outer frame. After the fabric is positioned and placed on the lower plate, the presser foot frame descends from above to hold the fabric.
With such a configuration, the cloth moving mechanism 80 can move and position the cloth at an arbitrary position on the XY plane via the holding frame 81, and can perform needle dropping at any position for each needle. Flexible seam formation is possible. That is, the cloth moving mechanism 80, which is also referred to as a moving mechanism, moves the cloth to any position along the horizontal surface to make the needle drop at any position.

[Yarn tension device]
FIG. 14 is a cross-sectional view of the thread tensioning device 70. As shown in FIG. The yarn tensioning device 70 mainly comprises a yarn tensioning device 79 for applying a yarn tension to the upper yarn, and a yarn tensioning solenoid 71 as a yarn tension adjusting actuator for variably adjusting the yarn tension by the yarn tensioning device 79.
The thread tensioner 79 is provided on the right side surface of the sewing machine arm portion 101a, and applies thread tension by gripping the upper thread from the thread supply source to the balance. The thread tensioner 79 includes two thread tensioning discs 72, 72 sandwiching the upper thread, and a hollow support shaft 73 movably supported along the X-axis direction in which the thread tensioning discs 72, 72 contact and separate from each other. And a pressing shaft 74 capable of pressing one thread tension disc 72 through the inside of the hollow support shaft 73 to the other thread tension disc 72, a thread take-up spring 75, and a main body case 76 for storing and holding these. And have.

On the other hand, the thread tension solenoid 71 is provided with an output shaft 71a that generates a thrust in a direction that protrudes in accordance with the value of the current supplied to the left of the thread tensioner 79. The output shaft 71a corresponds to the pressing shaft 74 described above. It is arranged to line up on the same line.
The output shaft 71a is coupled to the transmission shaft 78 inserted through the coil spring 77. The transmission shaft 78 is inserted through the coil spring 77 pressing the output shaft 71a in the direction of pushing back.
Therefore, when the thread tension solenoid 71 is not energized, the output shaft 71a is pushed back by the coil spring 77, and a pressing force for pressing the pressing shaft 74 in the direction of the thread tension disc 72 can not be obtained. 72 is free and no thread tension is applied.
When the thread tension solenoid 71 is energized, the output shaft 71a projects with a thrust corresponding to the current value, and the transmission shaft 78 presses one thread tension plate 72 via the pressing shaft 74 against the coil spring 77. In accordance with the pressing force, tension can be applied to the upper thread interposed between the two thread tensioning discs 72, 72.
The energization amount of the thread tension solenoid 71 is controlled by the control device 90, and the thread tension device 70 can apply any thread tension to the upper thread.
In addition, the control device 90 as the control unit performs a threading operation to perform thread shifting or a needle number of a plurality of needles including the hand movement, the calculated sewing direction falls into the classification of A or B described later (see FIG. 19). If it belongs, the thread tension solenoid 71 as a thread tension adjusting actuator is controlled to reduce and adjust the thread tension.

[Middle presser vertical movement mechanism]
FIG. 15 is a schematic configuration view of the middle pressing and moving mechanism 120. As shown in FIG. As shown, the middle presser-lifting mechanism 120 holds the middle presser 110 at its lower end and the middle presser bar 121 supported so as to be vertically movable in the sewing machine arm portion 101 a and the middle presser 110 through the middle presser bar 121. And the drive shaft 122 that performs reciprocating rotation around the Y axis in the same cycle as the upper shaft 22 by receiving power from the sewing machine motor 21 and the drive shaft 122 Drive arm 123 that reciprocates back and forth around Y axis, drive link 124 whose one end is connected to arm 123a extended in the rotation radial direction of drive arm 123, and one end is a sewing machine arm A pivoting arm 125 rotatably supported about the Y axis in 101a and having a longitudinal direction intermediate portion connected to the other end of the drive link 124, the other end of the pivoting arm 125, and the middle pressing rod 1 The first and second transmission links 127 and 128 for connecting the rod holder 126 fixedly mounted to 1 and one end of the first transmission link 127 and one end of the second transmission link 128 are about the Y axis. , And a guide plate 130 having a linear guide groove 130a slidably guiding the angular piece 129, and a square piece 129 rotatably mounted around the Y axis at these connecting portions. And a pivoting radial direction centering on the output shaft of the height adjusting motor 131 for giving a pivoting motion to the guide plate 130 and the height adjusting motor 131 along the Y-axis direction It mainly includes an output arm 132 extended outward, and a connection link 133 for connecting the output arm 132 and the guide plate 130.

  The upper end of the middle presser 110 is held by the lower end of the middle presser bar 121, and the lower end of the middle presser 110 has a cylindrical frame centered on the Z-axis direction, and the sewing needle 11 is at its center It has been loosely inserted. Further, the amplitude of the up and down movement of the middle presser 110 is smaller than the amplitude of the up and down movement of the needle bar 12, and the lower end of the sewing needle 11 is the lower end of the middle presser 110 when the sewing needle 11 reaches the top dead center. It is located above the top. As a result, when the sewing needle 11 ascends, the middle presser 110 can press the fabric pulled upward by the sewing needle 11 to hold the end of the fabric and completely pull out the sewing needle 11 from the fabric. ing.

The drive shaft 122 is given a reciprocating rotational movement from an upper shaft 22 which is rotationally driven by a sewing machine motor 21 via, for example, a crank mechanism. The rotation cycle of the upper shaft 22 and the reciprocation rotation cycle of the drive shaft 122 coincide with each other, whereby the vertical movement of the sewing needle 11 and the vertical movement of the middle presser 110 are synchronized.
The drive arm 123 is formed with an elongated hole 123b along the arm portion 123a, and one end of the drive link 124 can be connected to an arbitrary position in the elongated hole 123b by a fastening bolt 124a. Since the elongated hole 123b is formed along the turning radius of the drive arm 123, the amount of reciprocation applied to the drive link 124 is adjusted in proportion to the distance from the drive shaft 122 by changing the connection position thereof. be able to. Since the amount of reciprocation of the drive link 124 is approximately proportional to the amplitude of the vertical movement transmitted to the middle presser 110, the transmission position to the middle presser 110 is transmitted by changing the connection position of one end of the drive link 124 to the long hole 123b. It is possible to adjust the amplitude of vertical movement.
That is, the amplitude of the vertical movement of the middle presser 110 by means of the fastening bolt 124a which enables one end of the drive link 124 to be connected to an arbitrary position of the arm 123a of the drive arm 123 and the long hole 123b in which the long hole 123b is formed. Constitute an amplitude adjustment unit that adjusts the

The elongated hole 123b is curved in an arc shape having a radius substantially the same as that of the drive link 124, and one end of the drive link 124 with respect to the elongated hole 123b when the drive shaft 122 has a predetermined axial angle. By changing the connecting position, it is possible to adjust the vertical movement amplitude of the middle presser 110 without causing a change in posture from the pivoting arm 125 to the middle presser 110.
The elongated hole 123 b is formed to a position where the center of the drive shaft 122 and the rotation center of one end of the drive link 124 are concentric, and the rotation of the center of the drive shaft 122 and one end of the drive link 124 By adjusting the position of one end of the drive link 124 so as to be concentric with the center, it is possible to provide a stop state in which no operation is given to each member from the drive link 124 to the middle presser 110. That is, as a result, it is possible to perform sewing without moving the middle presser 110 up and down.

The other end of the pivoting arm 125 reciprocates by the drive link 124.
As described above, one end of the first transmission link 127 and the second transmission link 128 are pivotally coupled to each other about the Y axis, and the other end of the first transmission link 127 is Y It is connected to the other end of the pivoting arm 125 so as to be rotatable about its axis. Further, the other end of the second transmission link 128 is connected to the rod holder 126 so as to be rotatable about the Y axis.
Since the first transmission link 127 and the second transmission link 128 have a structure that can cause bending at the mutual connection portion, in the state as it is, the reciprocating arm 125 reciprocates up and down from the rod holder 126 Although the movement can not be transmitted, the connecting portion between each link 127 and 128 is equipped with a corner piece 129, and the behavior of the corner piece 129 is fixed in a straight direction by the guide groove 130a formed in the guide plate 130. Operation is regulated. Therefore, in a state where the guide plate 130 does not rotate and the fixed position is maintained, the first transmission link 127 and the second transmission link 128 can maintain a substantially constant bending angle, and the rotation arm Reciprocating vertical movement can be transmitted from the rod holder 125 to the rod holder 126.
Further, as shown in FIGS. 15A and 15B, when the guide plate 130 is rotated, the inclination angle of the guide groove 130a is changed, whereby the first transmission link 127 and the second transmission are transmitted. It is possible to change the bending angle of the link 128. Thus, the distance between the other end of the pivot arm 125 and the rod holder 126 can be changed, and the height of the middle presser 110 can be changed through the middle presser bar 121. By this height adjustment, the middle presser 110 can arbitrarily change the height of the whole range in which the up and down movement is performed.

Further, the guide plate 130, the output arm 132, and the connection link 133 constitute a so-called four-bar link mechanism, and by driving the height adjustment motor 131 in which the output shaft is connected to the output arm 132 which is one node thereof. The rotation angle of the guide plate 130 can be arbitrarily changed. That is, by controlling the amount of movement of the height adjustment motor 131, the height of the bottom dead center in the vertical movement of the middle presser 110 can be freely controlled.
That is, the first transmission link 127, the second transmission link 128, the square piece 129, the guide plate 130, the output arm 132, and the height adjustment motor 131 constitute a height adjustment portion for adjusting the height of the middle presser 110. doing. The height adjustment motor 131 also functions as an actuator for changing and adjusting the bottom dead center height of the middle presser 110.

[Control system of sewing machine: control device]
FIG. 16 is a block diagram showing a control system of the sewing machine 100. As shown in FIG. The sewing machine 100 includes a control device 90 as a control unit for controlling the operation of the above-described units and members. The control device 90 further includes a ROM 92 storing a program for performing operation control in sewing, a RAM 93 serving as a working area of arithmetic processing, and a non-volatile data memory 94 serving as storage means for storing sewing data. , And a CPU 91 that executes a program in the ROM 92.

The CPU 91 also includes a sewing machine motor drive circuit 21a, an X-axis motor drive circuit 83a, a Y-axis motor drive circuit 84a, a threading motor drive circuit 52a, a needle bar turning motor drive circuit 34a, and a height adjustment motor drive circuit 131a. For each of the sewing machine motor 21, X-axis motor 83, Y-axis motor 84, thread adjustment motor 52, needle bar rotation motor 34, height adjustment motor 131, and thread tension solenoid 71 via the thread tension solenoid drive circuit 71b. It is connected and controls the drive of each motor 21, 83, 84, 52, 34, 131 and the thread tension solenoid 71.
The sewing machine motor 21 also includes an encoder (not shown), and the detected angle is output to the CPU 91. The motors 83, 84, 52 and 34 are stepping motors, and their origin search means (not shown) are connected to the CPU 91, and the CPU 91 can recognize the origin position of each motor from its output.
The needle bar rotation mechanism 30 is also provided with a needle bar angle sensor 329 for detecting the origin position in the rotation angle range of the needle bar 12, and the CPU 91 determines the angle which becomes the origin of the needle bar 12 from its output. It can be detected.

The sewing data stored in the data memory 94 sequentially stores the operation amounts of the X-axis motor 83 and the Y-axis motor 84 for one stitch for sewing a predetermined sewing pattern, and the CPU 91 performs sewing In this case, the operation amounts of the X-axis motor 83 and the Y-axis motor 84 are read for each needle and operation control is performed to drive the X-axis motor 83 and the Y-axis motor 84 according to the respective operation amounts. That is, the control device (control unit) 90 controls the cloth moving mechanism 80 based on sewing data which defines the needle drop position for each needle or the movement amount of the cloth for forming a predetermined sewing pattern.
Further, the bottom dead center height of the middle presser 110 for each needle is stored in order in the sewing data, and based on this, the control device 90 controls the height adjustment motor 131 to carry out the middle for each needle. The bottom dead center height of the presser 110 is changed and adjusted.

  Further, the control device 90 is provided with an input device 95 as a setting input unit for performing various setting inputs. With this input device 95, it is also possible to perform setting input of the sewing pattern and setting input of the height of the bottom dead center of the middle presser 110 by the middle presser vertical movement mechanism 120.

[Hitch stitch occurrence factor]
The CPU 91 executes hitch stitch avoidance control with the execution of the sewing control based on the sewing data.
When the cloth moving mechanism 80 moves the cloth in an arbitrary direction for each needle according to the sewing data, the sewing needle 11 stitches the cloth according to the cloth feeding direction, that is, the stitch forming direction. The entanglement direction in which the upper thread U having passed through the eyelet 11a is entangled with the sewing needle 11 may be the left-handed direction shown in FIG. 17A or the right-handed direction shown in FIG. Depending on which one of these, it will be determined whether it will be a perfect stitch or a hitch stitch.
FIG. 18 (A) is a plan view showing the lower thread D extending from the corner of the bobbin case of the hook 13 to the needle hole 15 of the needle plate 14, and FIG. 18 (B) is a front view thereof. However, as shown in the figure, whether the stitch is a perfect stitch or a hitch stitch is determined depending on whether the sewing needle 11 falls to the L side or the R side with respect to the route of the lower thread D. Do.

Next, in the case of using a half-turn hook like the sewing machine 100 of the present embodiment, the relationship between the movement direction of the cloth and the generation factor of the hitch stitch will be described with reference to FIG. FIG. 19 shows which range the hitch stitch is generated in accordance with the direction or angle at which the cloth moving mechanism 80 feeds the cloth centering on the needle hole 15, and the factor thereof corresponds to any of the foregoing. .
First, the angular range of the feed direction of A is constant in the rightward direction with the upper thread entangled with respect to the sewing needle 11 depending on the feed direction. In addition, since the angular range of the feed direction of A substantially coincides with the direction in which the lower thread D moves from the bobbin toward the needle hole 15, the sewing needle 11 falls to the R side with respect to the lower thread passing through the needle hole 15 It is uncertain if it falls, so this area is the area where both perfect stitching and hitch stitching can occur.

  Next, the angle range of the feed direction of B is such that the feed direction is lower than the lower thread path and the side where the sewing needle 11 falls is surely L side, and this area is the upper thread relative to the sewing needle 11 Since the entanglement direction is on the right side, it is an area where the hitch stitch will surely be made.

  Next, the range of the feeding direction of C is that the feeding direction is surely L side with respect to the lower thread path and the side to which the sewing needle 11 falls is not unfixed since the upper thread entanglement direction with respect to the sewing needle 11 It is an area where both perfect stitching and hitch stitching can occur.

  As for the range of the feeding direction of the remaining D, the feeding direction is surely R side with respect to the lower thread path and the side where the sewing needle 11 falls is the R side and the upper thread entanglement direction with respect to the sewing needle 11 is the left. It is an area where

[Control device: Hitch stitch avoidance control]
As described above, in the sewing machine 100, the position at which the sewing needle 11 falls with respect to the lower thread path connected to the needle hole 15 from the hook (bobbin case) is either the perfect stitch or the hitch stitch. Two factors with the direction of yarn entanglement are determined, and in the area where each factor becomes uncertain, the type of stitch also tends to be uncertain.
Therefore, in the sewing machine 100, the range of the feeding direction by the cloth moving mechanism 80 is divided into four of A to D described above, and the angular range of each section is registered in the data memory 94. Furthermore, as shown in FIG. 20, table data storing which of the thread shifting by the thread shifting mechanism 50 and the needle bar pivoting by the needle bar pivoting mechanism 30 should be executed according to each of the sections A to D Registered in data memory.

Then, when sewing is performed, the control device 90 performs the following hitch stitch avoidance control. That is, when the movement amounts of the X-axis motor 83 and Y-axis motor 84 for one stitch are read from the sewing data in order to sew a predetermined sewing pattern, the movement direction of the cloth is obtained from the movement amounts in the X-axis direction and the Y-axis direction. Is determined to belong to any of the categories A to D. Then, according to the determined classification, it is specified from the table data which one of thread shifting and needle bar rotation should be executed, and the thread shifting is performed so that each operation is performed at the upper axis angle according to each execution timing. The thread shifting motor 52 of the mechanism 50 or the needle bar rotation motor 34 of the needle bar rotation mechanism 30 is controlled.
The control device 90 as the control unit calculates the moving direction of the cloth when each cloth is dropped by the cloth moving mechanism 80 from the needle drop position or the movement amount of the cloth determined in the sewing data. It is determined to which category of A to D it belongs.
Then, in the case of the first angle range A or B in which the moving direction is a predetermined first angle range, the thread shifting by the thread shifting mechanism 50 is performed, and in the case of the second angle range C, the needle bar is rotated. The rotation of the needle bar by the mechanism 30 is executed, and in the case of the third angle range D, the yarn shifting by the thread pulling mechanism 50 and the rotation of the needle bar by the needle bar rotation mechanism 30 are not executed. The control device 90 as the control unit calculates the movement direction of the cloth at the time of each needle drop by the cloth moving mechanism 80 from the needle drop position or the movement amount of the cloth determined in the sewing data. Instead of this, angle range data that the first angle range A or B, the second angle range C, and the third angle range D are set in advance in sewing data, and control is performed based on those data It is also easily conceivable for the device 90 to control the rotation of the needle bar and the presence or absence of the execution of the threading.
That is, the control device 90 as the control unit operates the yarn moving mechanism 50 in the case where the moving direction of the fabric for each needle drop by the fabric moving mechanism 80 is A or B, which is a predetermined first angle range. When the movement direction is a predetermined second angle range C, rotation of the needle bar by the needle bar rotation mechanism 30 is performed.

[Control device: Execution timing of needle bar rotation]
Next, an appropriate timing when executing needle bar rotation in the hitch stitch avoidance control will be described. FIG. 21 is a diagram showing the relationship between the upper shaft angle and the height of the sewing needle 11.
When the needle bar 12 performs reciprocating rotation, it is required that the forward rotation of the needle bar 12 be completed before the lower end of the sewing needle 11 reaches the cloth on the needle plate 14. That is, the upper shaft angle at which the lower end portion of the sewing needle 11 reaches the cloth on the needle plate 14 is taken as a needle penetration angle α. The needle penetration angle α shown in FIG. 21 does not take into account the thickness of the fabric, and when the thickness is 0, that is, the upper axial angle at which the lower end portion of the sewing needle 11 reaches the upper surface of the needle plate 14 Is shown. Hereinafter, this needle bite angle α is referred to as a reference needle bite angle α.
When the thickness of the fabric is taken into consideration, the arrival of the sewing needle 11 is faster by the thickness, so it is necessary to complete the forward needle bar pivoting earlier than the reference needle biting angle α.
In addition, the thickness of the fabric is approximately equal to the bottom dead center height of the middle presser 110 that moves up and down.
Accordingly, assuming that the set value of the bottom dead center height of the middle presser 110 from the upper surface height h0 of the needle plate 14 is Δz, the upper axis angle for completing the forward rotation of the needle bar 12 is calculated as follows: It can be determined by

In FIG. 21, the vertical axis indicates the height of the lower end portion of the sewing needle 11, and the center of the vertical movement of the sewing needle 11 is set to height 0. The height Z of the lower end portion of the sewing needle 11 is expressed by the following equation (1) when the amplitude of the needle bar 12 is H, the upper axis angle is θ, and the upper axis angle of the top dead center of the needle bar is 0 °. .
Z = (H / 2) · cos θ (1)

Further, the top surface height h0 of the needle plate is expressed by the following equation (2).
h0 = (H / 2) · cos α (2)

Assuming that the set value of the bottom dead center height of the middle presser 110 is Δz and this is regarded as the thickness of the fabric, the upper axis angle β at which the forward movement of the needle bar 12 should be completed is expressed by the following equations (3), (4) It can be represented by).
(H / 2) · cos β = (H / 2) · cos α + Δz (3)
β = cos ⁻¹ (cos α + (2 / H) · Δz) (4)

Therefore, the upper axis angle difference Δθ between the reference needle stick angle α and the upper axis angle β for completing the forward rotation of the needle bar 12 considering the thickness of the cloth is expressed by the following equation (5).
Δθ = α-β
= Α-cos ^-1 (cos α + (2 / H) · Δz) (5)

When the lower dead center height Δz of the middle presser 110 is set from the input device 95, the controller 90 uses the set value Δz to complete the rotation of the forward movement of the needle bar 12 according to the above equation (4). Calculate the angle β. Next, the control device 90 calculates the drive start upper shaft angle θs for starting the drive of the needle bar turning motor 34 from the calculated upper shaft angle β.
The time required for the needle bar turning motor 34 to start driving from the state where the boss 36 is positioned at the starting point 352a of the needle bar cam member 35 and to reach the intermediate point 352b (see FIG. 11) tm [s] Assuming that the set rotational speed of the sewing machine motor 21 is mo [rpm], the drive start upper shaft angle θs [deg] is calculated by the following equation (6).
θs = β−360 · mo · (1/60) · tm
= Cos ^-1 (cos α + (2 / H) · Δz)-(360/60) · mo · tm (6)

When sewing, when performing needle bar rotation, the control device 90 calculates the drive start upper shaft angle θs, and the upper shaft angle detected by the encoder provided on the sewing machine motor 21 is the drive start upper shaft angle When θs is reached, drive start of the needle bar turning motor 34 is executed. In the sewing data, when the bottom dead center height Δz of the middle presser 110 or the number of rotations of the sewing machine motor 21 is set for each needle, the drive start upper shaft angle from those setting values for each needle The start of driving of the needle bar turning motor 34 is controlled by calculating θs.
And thereby, when the needle 11 and the sewing needle 11 reach the cloth, the forward rotation is completed, and the needle bar is rotated at an appropriate timing, not too late nor too late, effectively hitch stitching It is possible to suppress the occurrence of The needle bar turning motor 34 continues to turn as it is after the forward movement is finished, and stops driving after completing the return movement of the needle bar 12. At this time, the backward movement of the needle bar 12 is completed with sufficient time until the point of the hook of the hook reaches the upper shaft angle at which the upper thread loop is captured.

[Control device: Execution timing of thread shifting]
Next, an appropriate timing in the case of executing thread shifting in the hitch stitch avoidance control will be described. FIG. 22 is a motion diagram of the sewing needle 11, the hook 13, and the balance 16 (see FIG. 2) of the sewing machine 100. In FIG. 22, a black line indicates a needle bar curve, a black line indicates a basic curve, and a black line indicates a balance curve. 23 and 24 are plan views showing the positional relationship between the thread shifting member 51 and the needle hole 15, and FIG. 23 shows a state in which the thread shifting is not performed, and FIG. 24 performs the thread shifting. Show the condition.

As shown in FIG. 23 and FIG. 24, since the thread shifting member 51 crosses the needle hole 15 which is the needle dropping position, in the execution of the thread shifting, the forward movement of the thread shifting member 51 is the reference needle penetration angle. It is desirable that the forward movement of the yarn transfer member 51 be completed by α. Since the threading is performed below the needle plate 14, it is not necessary to consider the thickness of the fabric as in the case of needle rotation.
Therefore, the thread shifting motor 52 of the thread shifting mechanism 50 is at least in the middle position from the state where the boss portion 54 is positioned at the starting point of the thread shifting cam member 53 than the timing of reaching the reference needle bite angle α (113 °). It is controlled to start driving from the front only by the required time to reach the point.
In addition, the return path of the thread shift member 51 may be performed by rotating the return path of the thread shift member 51 at an upper thread opening angle at which the upper thread is 270 ° away from the sewing needle 11 by the hook. desirable. Therefore, the thread shifting motor 52 of the thread shifting mechanism 50 is driven earlier than the upper opening angle by the time required for the boss 54 to be located at the middle point of the thread shifting cam member 53 to reach the start point. Is controlled to resume the
The rotation operation of the yarn transfer member 51 requires high-speed operation for both forward and backward travel, but the yarn transfer motor 52 reaches a section that contributes to the rotation of the yarn transfer in a high speed state after running in the approach section. Therefore, the threading member 51 can be rotated at high speed, and it is possible to sufficiently cope with the request for operation at a short timing.

[Yarn tension adjustment control at the time of execution of yarn alignment]
As shown in FIG. 25, when the yarn shifting is performed, the lower yarn is brought close to the yarn shifting member 51, the path length becomes long, and the bobbin is pulled out from the bobbin side.
Therefore, even if the upper thread tension is set smaller than usual, the upper and lower thread knots can be pulled up to the upper side of the cloth, and a low tension and tight seam can be formed.
Therefore, at the time of the needle drop determined to be the execution of the thread shifting at the time of sewing, the control of the thread tension solenoid 71 is executed so as to reduce the thread tension.
At this time, the thread tension of the thread tension solenoid 71 may be automatically determined by automatically reducing the set value of thread tension set in the sewing data by a predetermined amount or reducing it by a predetermined ratio. Or, set a thread tension value suitable for executing the threading in advance, and control the thread tension solenoid 71 so that the thread tension value suitable for executing the threading becomes uniform at the time of executing the threading. Also good.
As described above, by performing control to reduce the thread tension at the time of threading, it is possible to achieve uniform threading tightness between the stitch that performs threading and the stitch that is not performed.

[Operation explanation of hitch stitch avoidance control]
FIG. 26 is a flowchart of hitch stitch avoidance control. Here, the rotation speed of the sewing machine motor 21 is constant, and the bottom dead center height of the middle presser 110 is set in the sewing data for each needle.
As illustrated, when the control device 90 of the sewing machine 100 executes the sewing based on the sewing data, if the upper axis angle becomes a predetermined data reading angle, the X-axis direction and Y axis of the next movement are obtained from the sewing data. Reading of the movement amount in the direction and the bottom dead center height of the middle presser 110 is executed (step S1).

Then, the height adjustment motor 131 is controlled based on the read setting value of the bottom dead center height of the cloth presser 100 to change the bottom dead center of the middle presser 110 to the set value (step S3).
Further, the control device 90 calculates the cloth movement direction, that is, the sewing direction, from the read amounts of movement in the X-axis direction and the Y-axis direction read (step S5).

Next, the control device 90 refers to the table of FIG. 26 described above and determines whether the calculated sewing direction belongs to the classification of A or B (step S7).
As a result, when the sewing direction belongs to the classification of A or B, the thread tension solenoid 71 is controlled to reduce the thread tension to a thread tension suitable for threading (step S9). Further, the upper shaft angle is monitored, and driving of the thread shifting motor 52 is started at an appropriate timing to execute thread shifting (step S11). As a result, even if the sewing direction belongs to the section A or B, the needle is dropped to the right side of the lower thread, and perfect stitching is performed.

In step S7, when the sewing direction does not belong to any of A and B, it is determined whether it belongs to the C classification (step S13).
Thereby, when the sewing direction is a division of C, the control device 90 calculates the drive start upper axis angle θs described above (step S15). Then, the upper shaft angle is monitored, and when the drive start upper shaft angle θs is reached, the drive of the needle bar rotation motor 34 is started to execute the rotation of the needle bar 12 (step S17).
As a result, it is possible to make the upper thread wrap around the sewing needle 11 on the left side, and perfect stitching is performed.
Further, in step S13, when the sewing direction does not belong to the section C, the sewing direction is the section D. Therefore, normal hand movement is performed without performing the thread shifting and the needle bar rotation.

[Effect of the embodiment]
As described above, in the sewing machine 100, the sewing direction of each needle is determined, and the threading or needle bar turning operation is selectively performed according to the sewing direction. Therefore, the hitch stitch can be prevented not only by the hitch stitch generated due to the needle drop position with respect to the lower thread but also by the entanglement direction of the upper thread with respect to the sewing needle 11. It is possible to reduce the occurrence more effectively. Further, since a plurality of factors are dealt with, it is possible to prevent the occurrence of the hitch stitch even when using various pots such as vertical pots, horizontal pots, full rotary pots and semi rotary pots.

  In addition, the control device 90 controls the height adjustment motor 131 of the middle presser-lifting mechanism 120 so that the bottom dead center height of the middle presser 110 becomes a preset setting value, and the lower presser of the middle presser 110 The needle bar turning mechanism 30 is controlled so that the forward movement is finished at the timing when the tip of the sewing needle 11 reaches the set value of the point height. Therefore, the needle bar 12 can finish the forward rotation at the timing when the lower end portion of the sewing needle 11 reaches the upper surface of the fabric, and the sewing needle 11 does not pierce the fabric before the rotation is finished. The needle bar pivoting can be performed at an appropriate timing without the needle bar pivoting being completed prematurely with respect to the arrival time of the cloth. This makes it possible to reduce the occurrence of hitch stitch more effectively.

[Others]
Although the needle bar turning mechanism 30 and the yarn pulling mechanism 50 use the groove cam for generating the reciprocation, the invention is not limited thereto. For example, other cams that can obtain reciprocating motion such as an end face cam or an outer peripheral cam may be used.
In addition, the cam groove of needle bar turning mechanism 30 and thread pulling mechanism 50 is made endless ring, and the groove cam is rotated only in a fixed direction, but in response to the reciprocation of needle bar 12 or thread pulling member 51 The cams may be configured to perform reciprocating rotation.
Further, the needle bar rotating mechanism 30 and the thread shifting mechanism 50 may be reciprocated by a crank mechanism, a four-node cam mechanism or the like without being limited to the cam. Further, in the operation of the yarn positioning by the yarn positioning member 51, it is sufficient if the bobbin thread can be drawn backward from the lower side of the needle hole 15, and the tip of the yarn positioning member 51 does not have to follow the same locus in the forward path and the return path. . For example, the tip end of the threading member 51 may perform an oval, an oval, or another circular motion to perform the threading.

  In the above embodiment, since the bottom dead center height of the middle presser is set for each needle in the sewing data, the drive start upper shaft angle θs is calculated for each needle, for example, the input device 95 From the above, when a constant value is set throughout the sewing for the bottom dead center height of the middle presser and the rotational speed of the sewing machine motor 21, the drive start upper shaft angle θs is not calculated for each needle, and the sewing start The drive of the needle bar turning motor 34 may be started each time according to the fixed value of the drive start upper shaft angle θs calculated previously.

11 sewing needle 12 needle bar 13 hook 20 needle vertical movement mechanism 21 sewing machine motor 22 upper shaft 30 needle bar rotation mechanism 34 needle bar rotation motor 80 cloth movement mechanism (movement mechanism)
81 Holding frame (cloth holding unit)
90 Control unit (control unit)
95 Input device (setting input unit)
100 sewing machine 110 middle presser 120 middle presser vertical movement mechanism 131 middle presser adjustment motor (actuator)
D Lower thread U Upper thread

Claims (4)

A needle bar that holds a sewing needle and moves up and down,
A hook for winding the upper thread to the lower thread by a pivoting operation;
A sewing machine motor serving as a driving source of vertical movement of the needle bar;
A needle bar turning mechanism for turning the needle bar around a center line along its longitudinal direction;
A movement mechanism for moving the sewing material along a horizontal plane in an arbitrary movement direction by the cloth holding unit to cause needle dropping at an arbitrary position;
A control unit that controls the moving mechanism based on sewing data that defines a needle drop position for each needle or a movement amount of the sewing material for each needle for forming a predetermined sewing pattern;
A middle presser which is juxtaposed to the sewing needle and prevents lifting of the material to be sewn held by the cloth holding unit;
A middle presser elevating mechanism including an actuator for moving the middle presser up and down in synchronization with the needle bar and changing and adjusting the bottom dead center height of the middle presser;
The needle bar is moved by the needle bar turning mechanism from the forward path and the return path when the control unit belongs to an angle range in which the movement direction of the sewn material determined in the sewing data is generated by a predetermined hitch stitch. In a sewing machine that performs control so as to perform the reciprocal reciprocating movement
The control unit controls an actuator of the middle presser-lifting mechanism so that the lower dead center height of the middle presser becomes a preset set value, and the set value of the lower dead center height of the middle presser From the above, the drive start timing of the needle bar turning mechanism is calculated using the fact that the bottom dead center height of the inner presser matches the thickness of the sewing material, and the tip of the sewing needle is made of cloth A sewing machine characterized in that the needle bar turning mechanism is controlled such that the forward movement of the needle bar is completed before reaching the needle bar. The lower side of the needle plate is provided with a yarn moving mechanism for moving the lower yarn by a yarn moving member,
The control unit
When the moving direction of the sewing material for each needle drop by the moving mechanism is a predetermined first angle range, thread shifting by the thread shifting mechanism is executed;
The sewing machine according to claim 1, wherein when the movement direction is a predetermined second angle range, rotation of the needle bar by the needle bar rotation mechanism is performed.   The sewing machine according to claim 1 or 2, further comprising a setting input unit configured to set a setting value of the bottom dead center height of the middle presser. The set value of the bottom dead center height of the middle presser per needle is set in the sewing data,
The sewing machine according to any one of claims 1 to 3, wherein the control unit controls an actuator of the middle pressing and lowering mechanism and the needle bar turning mechanism for each needle.

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