CN110295462B

CN110295462B - Sewing machine

Info

Publication number: CN110295462B
Application number: CN201910223998.4A
Authority: CN
Inventors: 中野元就; 竹村徹
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-03-23
Filing date: 2019-03-22
Publication date: 2021-06-15
Anticipated expiration: 2039-03-22
Also published as: CN110295462A; JP2019166038A

Abstract

The invention relates to a sewing machine, which can reduce the uneven condition of the sewing allowance after cutting the sewing by a thread cutting device and can prevent the poor sewing when starting the next sewing. The sewing machine has a supply part. The supply part is provided with a driver, and the supply part can supply the suture between the thread clamping disc and the stitch by using the power of the driver. The control part of the sewing machine forms stitches on the cloth by controlling the driving of the sewing part. The control part starts the driving of the thread cutting device before stopping the driving of the sewing part. The control part controls the driving of the supply part at the same time of controlling the driving of the thread cutting device, so that a specified amount of thread is supplied between the thread clamping disc and the stitches. The control part stops the drive of the sewing part after controlling the drive of the supply part to supply the suture between the thread clamping disk and the stitch.

Description

Sewing machine

Technical Field

The present invention relates to a sewing machine.

Background

A sewing machine capable of controlling the tension of an upper thread at the time of sewing is known. For example, a sewing machine disclosed in japanese laid-open patent publication 1997 No. 220391 has a reel, a hysteresis brake and a motor. The hysteresis brake has an output shaft. The reel is fixed in the hysteresis brake. The wire wheel is wound with a surface wire. The upper thread tension is inputted to the sewing machine by an operator. When the motor is driven, the sewing machine executes a sewing action. When the motor is driven, the upper thread winds around the thread wheel, and the thread wheel rotates according to the movement amount of the upper thread. The current is supplied to the hysteresis brake through the sewing machine, so that the brake force is generated according to the action of the wire wheel to rotate. The braking torque of the hysteresis brake exerts tension against the extraction direction of the upper thread. The sewing machine controls the braking torque by controlling the current supplied to the hysteresis brake, so as to control the upper thread tension.

The sewing machine cuts the upper thread when sewing is finished. In this case, if the needle thread remaining on the needle after cutting is relatively large, the needle thread may be knotted and lumped below the fabric when the next sewing is started. When the remaining amount of the upper thread remaining on the needle after the cutting is relatively small, the upper thread may be separated from the needle at the start of the next sewing. The sewing machine is controlled when the upper thread is cut off to reduce the braking torque of the hysteresis brake, thereby reducing the tension of the upper thread. The remaining amount of the upper thread remaining on the needle after cutting is determined by the following tension: tension generated along with the control of the braking torque of the hysteresis brake; tension imparted by a pretensioning device of a sewing machine; and a tension generated by the resistance applied to the upper thread by the action of the thread cutting device, including the resistance on the upper thread feeding path when the upper thread is cut. This tension ratio is low and may be unstable. For example, in the case where the tension is too high when the upper thread is to be cut, the upper thread is already cut before the cutting is performed, or the upper thread is released from the needle after the cutting. When the tension is too low when the upper thread is cut, the reel idles, and the excessive upper thread is wound around the reel. Therefore, the margin of the upper thread remaining on the needle after the cutting is uneven, and there is a possibility that a defective sewing may occur at the start of the next sewing.

Disclosure of Invention

The invention aims to provide a sewing machine which can reduce the uneven condition of the thread allowance after cutting the thread by a thread cutting device and can prevent the poor sewing when starting the next sewing.

The sewing machine of claim 1 comprises: a sewing part having a needle bar to which a needle is attached and which is capable of moving up and down, the sewing part being capable of forming a stitch on a fabric using the needle; a suture thread take-up reel around which a suture thread is wound; a thread cutting device capable of cutting the suture below the needle shaft; and a control unit for controlling the drive of the sewing unit and the thread cutting device, wherein the sewing machine has a supply unit having a driver, the supply unit being capable of supplying the thread between the thread clamping disk and the stitch by using the power of the driver, the control unit functions as a sewing control unit for controlling the drive of the sewing unit to form the stitch in the fabric, a thread cutting control unit for starting the control of the drive of the thread cutting device, and a stop control unit for controlling the drive of the supply unit to supply the thread between the thread clamping disk and the stitch at the same timing when the drive of the thread cutting device is controlled by the thread cutting control unit to supply a predetermined amount of the thread between the thread clamping disk and the stitch, the stop control unit being configured to supply the thread to the stitch by controlling the drive of the supply unit by the supply control unit And stopping the driving of the sewing part controlled by the sewing control part after the thread clamping disk and the stitches are inserted. In this case, the sewing machine controls the driving of the supply unit at the same timing as the control of the driving of the thread cutting device, and supplies a predetermined amount of the thread between the thread take-up reel and the stitch. The tension of the thread when the thread is cut by the thread cutting device is stabilized by the predetermined amount of the thread supplied. Therefore, the sewing machine can reduce the uneven condition of the thread allowance after cutting the thread by the thread cutting device, and can prevent the poor sewing when starting the next sewing.

In the sewing machine according to claim 2, the actuator may be a motor having an output shaft that rotatably supports the thread take-up reel, the motor may apply tension to the thread by rotating the thread take-up reel via the output shaft, and the supply control unit may control the driving of the motor to rotate the thread take-up reel in the thread supplying direction at the same timing when the driving of the thread cutting device is controlled by the thread cutting control unit, thereby supplying the predetermined amount of the thread between the thread take-up reel and the stitch. In this case, the sewing machine can rotate the thread take-up reel by controlling the driving of the motor, and supply a predetermined amount of the thread between the thread take-up reel and the stitch. Since the driver is a motor, the sewing machine can accurately supply a specified amount of thread between the thread clamping disk and the stitch. In the sewing machine, the structure near the supply path can be made simpler than the case where the supply portion is provided near the supply path of the suture independently of the suture clamping disk.

The sewing machine according to claim 3 may further include an input unit configured to input the predetermined amount to be supplied between the thread nipping plate and the stitch, wherein the control unit may further function as a thread amount obtaining unit configured to obtain the predetermined amount input by the input unit, and a calculation unit configured to calculate a rotation amount of the output shaft of the motor required to supply the predetermined amount of the thread obtained by the thread amount obtaining unit between the thread nipping plate and the stitch, and wherein the supply control unit may control the driving of the motor to rotate the output shaft by the rotation amount calculated by the calculation unit at the same timing of controlling the driving of the thread cutting device. In this case, the sewing machine can supply a predetermined amount of the thread inputted by the input portion between the thread clamping plate and the stitch. The operator can set an optimum predetermined amount in consideration of the sewing conditions.

In the sewing machine according to claim 4, the supply control unit may supply the predetermined amount of the suture between the thread clamping disk and the stitch before the predetermined amount of the suture is cut at the same timing as the timing at which the thread cutting device is controlled to be driven. In this case, the sewing machine can supply a predetermined amount of the thread between the thread chuck and the stitch before cutting the thread at the same timing of controlling the driving of the thread cutting device. In the sewing machine, compared with the case that a specified amount of the thread is supplied between the thread clamping disk and the stitch after the thread is cut at the same time of controlling the driving of the thread cutting device, the thread tension when the thread is cut by the thread cutting device can be reliably stabilized by using the supplied specified amount of the thread.

Drawings

Fig. 1 is a perspective view of the sewing machine 1.

Fig. 2 is a sectional view of the supply mechanism 60.

Fig. 3 is a schematic view of the output shaft 18 and the coil 33 of the clamp motor 16.

Fig. 4 is a block diagram of an electrical structure of the sewing machine 1.

Fig. 5 is a graph showing the first relational expression and the second relational expression.

Fig. 6A to 6D are explanatory diagrams showing a flow of capturing the upper thread 6 by the rotating hook 39.

Fig. 7 is an explanatory diagram showing a needle bar movement curve of the needle bar 11, a thread take-up lever thread amount curve of the thread take-up lever 51, and a shuttle thread amount curve of the rotary hook 39.

Fig. 8 is a flowchart of the sewing process.

Fig. 9 is a flowchart of the clamp motor driving process.

Detailed Description

Embodiments of the present invention will be described. The following description uses the left and right, front and back, and up and down indicated by arrows in the drawings. The sewing machine 1 shown in fig. 1 is a knotter for forming knotted stitches on a cloth 99.

Referring to fig. 1 to 6A, a general structure of the sewing machine 1 will be described. The sewing machine 1 has a bed 2, a column 3, and a arm 4. The bed 2 is a base of the sewing machine 1, and is provided on a table extending horizontally. The base unit 2 includes a base main body 7 and a cylindrical base unit 8. The base main body portion 7 has a substantially box shape. The cylindrical housing part 8 extends forward from the housing main body part 7. The inside of the housing main body 7 and the inside of the cylindrical housing 8 communicate with each other. The tubular bed portion 8 has a needle plate 26 on the upper surface of the front end portion. The operator places the cloth 99 on the needle plate 26. Needle plate 26 has needle receiving holes. The pillar 3 extends upward from the rear portion of the base body 7. The arm portion 4 extends forward from an upper portion of the column portion 3 and faces the base portion 2. The front end of the arm 4 is a tip 5. The distal end portion 5 has a right wall portion 5A and a through hole 5B (see fig. 2). The right wall portion 5A is a wall portion of the tip portion 5 located on the right side. The through hole 5B penetrates the right wall portion 5A in the left-right direction.

As shown in fig. 4, the sewing machine 1 has a control device 30, an operation portion 46, and a pedal 38. The control device 30 is fixed to the lower surface of the table. The control device 30 controls the operation of the sewing machine 1. The operation portion 46 is fixed to the upper surface of the table. The operation unit 46 includes a display unit 48 and an operation knob 47. The display unit 48 can display various information. The operation knob 47 can detect various information input by the operator. The operation knob 47 includes a power knob.

As shown in fig. 1, the sewing machine 1 has a sewing mechanism 12. The sewing mechanism 12 has a needle bar 11, the needle bar 11 is equipped with a needle 10, and the needle bar 11 can move up and down, and the sewing mechanism can form a stitch 98 (see fig. 6A) on a fabric 99 by the needle 10. The sewing mechanism 12 includes a main motor 27 (see fig. 4), an upper shaft 15, a link, a thread take-up mechanism, a needle bar up-and-down movement mechanism, a shuttle drive mechanism, and a cloth feeding device 20. The main motor 27 is supported at the rear of the arm portion 4. The upper shaft 15 extends in the front-rear direction inside the arm portion 4. The rear end of the upper shaft 15 is coupled to an output shaft of the main motor 27 via a coupling. The upper shaft 15 can be rotated by the main motor 27. The front end and the rear end of the upper shaft 15 are coaxial with each other. The upper shaft 15 has a crank portion near the rear end portion. The crank portion is eccentric with respect to the axes of the front and rear ends of the upper shaft 15. The link extends in the vertical direction inside the column portion 3. The upper end portion of the connecting rod is connected to the crank portion so that the connecting rod can rotate relative to the crank portion. The connecting rod can reciprocate along with the rotation of the upper shaft 15.

The thread take-up mechanism and the needle bar up-and-down movement mechanism are supported by the tip end portion 5. The thread take-up mechanism has a thread take-up crank and a thread take-up lever 51. The thread take-up crank is connected to the front end of the upper shaft 15. The thread take-up lever 51 is provided to the thread take-up crank. The thread take-up lever 51 moves up and down in conjunction with the up-and-down movement of the needle bar 11 by the rotation of the thread take-up crank together with the upper shaft 15. The thread take-up lever 51 has an upper thread through hole. The thread take-up lever 51 holds the upper thread 6 inserted in the upper thread passing hole. The needle thread 6 (see fig. 6A) is fed from the needle thread supply source and is fed to the needle thread punch of the thread take-up lever 51 via a feeding mechanism 60 described later.

The needle bar up-and-down motion mechanism is provided with a needle bar crank connecting rod, a needle bar 11 and the like. The needle bar crank connecting rod is connected with the thread take-up crank in a rotatable mode and extends along the vertical direction. The needle bar 11 extends in the vertical direction and is connected to the needle bar crank link. The lower end of the shank 11 is fitted with a needle 10. The needle 10 has an eye 10A at a lower end (see fig. 6A). The upper thread 6 perforated by the upper thread of the thread take-up lever 51 can be inserted into the eye 10A of the needle 10, so that the needle 10 holds the upper thread 6. The needle bar 11 moves up and down together with the needle 10 by the reciprocating movement of the needle bar crank link by the rotation of the thread take-up crank.

The shuttle drive mechanism is provided inside the housing unit 2, and has a lower shaft and a rotating shuttle 39. The lower shaft extends in the front-rear direction inside the housing main body 7 and inside the cylindrical housing part 8, and is rotatable. The lower shaft is connected to the link via a connecting portion, and the lower shaft is capable of reciprocating rotation in conjunction with the reciprocating motion of the link.

As shown in fig. 6A, the rotary hook 39 is provided at the front end of the lower shaft and below the needle receiving hole. The rotary hook 39 can rotate about a lower shaft. The rotary hook 39 has a hook tip 36 (see fig. 6A). The hook tip 36 is a part of the outer peripheral portion of the rotary hook 39, and protrudes toward the clockwise direction in the front view with the lower axis as the center. The bobbin case 32 can be fitted into the rotary hook 39. The bobbin case 32 accommodates a bobbin around which the lower thread 9 is wound. The bobbin case 32 has a lead-out portion 34. The bobbin thread 9 fed out from the bobbin can be guided to the outside by the lead-out portion 34.

As shown in fig. 1 and 4, the cloth feeding device 20 includes a movable body 31, a swing shaft, a cloth feeding table 37, a swing motor 41, a cloth feeding plate, a rack shaft 22, a moving motor 42, a pressing arm 23, and a cloth pressing motor 43. The movable body 31 is provided inside the base main body 7 so as to be movable forward and backward. The swing shaft is a shaft fixed to the movable body 31 and extending in the vertical direction, and protrudes upward from the base main body 7. The cloth feeding table 37 is connected to the movable body 31 inside the base body 7, and is provided on a swing shaft so as to be swingable. Therefore, the cloth feeding table 37 can move forward and backward together with the movable body 31 and can swing in the left-right direction about the swing axis. The swing motor 41 is connected to the cloth feeding table 37. The cloth feeding table 37 is driven by the swing motor 41 to swing about a swing axis. The cloth feeding plate is disposed on the upper surface of the base unit 2. The cloth feed plate supports the cloth 99. The cloth feeding plate is movable back and forth integrally with the cloth feeding table 37 and is swingable integrally with the cloth feeding table 37. The cloth feeding plate has a hole at the front end. The needles 10 moving up and down pass through the holes in the feed plate to the needle receiving holes in the needle plate 26.

The rack shaft 22 extends in the front-rear direction above the housing main body 7 and is movable forward and backward. The front end of the rack shaft 22 is coupled to the upper end of the swing shaft, and the rear end of the rack shaft 22 is located inside the column part 3. The movement motor 42 is provided inside the column part 3. The moving motor 42 can move the rack shaft 22 back and forth. In this case, the cloth feeding table 37, the cloth feeding plate, the swing shaft, and the movable body 31 move back and forth integrally with the rack shaft 22.

The pressing arm 23 extends upward from the cloth feeding table 37 and forward above the bed unit 2. The pressing arm 23 is movable back and forth integrally with the cloth feed table 37 and is swingable integrally with the cloth feed table 37. The presser arm 23 has a presser foot 24, a shaft portion 29, and a lever portion 25. The presser foot 24 is provided above the needle plate 26 so as to be movable up and down and is provided at the front end of the presser arm 23. The shaft portion 29 is provided at a substantially central portion in the front-rear direction of the pressure arm 23, with the left-right direction being an axial direction. The lever portions 25 are provided on the left and right surfaces of the pressing arm 23, respectively, and are rotatable about the shaft portion 29. The front end of the lever 25 is connected to the presser foot 24. The cloth pressing motor 43 is provided inside the column part 3. The cloth pressing motor 43 is connected to the rear end of the lever 25 via a link mechanism provided inside the arm 4. The presser foot 24 moves up and down by the lever portion 25 rotating about the shaft portion 29 in accordance with the driving of the presser motor 43. The presser foot 24 can press the cloth 99 between the presser foot 24 and the cloth feeding plate.

As shown in fig. 1 and 2, the sewing machine 1 includes a supply mechanism 60 on a right wall portion 5A of the distal end portion 5. The supply mechanism 60 includes a thread take-up drum 62, a thread take-up holder 63, a thread take-up spring 65, a thread take-up motor 16, a thread take-up reel 69, and an encoder 21 (see fig. 4). The feed mechanism 60 is capable of feeding the suture between the chuck 69 and the stitch 98 using the power of the pinch motor 16. The wire clamping tube 62 is an annular member fixed to the inside of the through hole 5B of the right wall portion 5A by a fastening member. The wire holder 63 is a ring-shaped member fixed to the inside of the wire-clamping cylinder 62 by the screw 14. The thread take-up spring 65 is fixed to the outer side surface of the thread clamping base 63 and wound between the thread clamping base 63 and the thread clamping cylinder 62. One end portion of the thread take-up spring 65 is exposed rightward from the right wall portion 5A. The wire clamping motor 16 is fixed to the inside of the arm part 4 by bolts. The clamp motor 16 has an output shaft 18, and the output shaft 18 penetrates a center hole of the clamp base 63 and protrudes to the right of the right wall portion 5A. The output shaft 18 is rotatable in the left-right direction as an axial direction, and a right end portion thereof rotatably supports the chuck 69 on the right side of the arm portion 4. In the present embodiment, the output shaft 18 is directly coupled to the chuck 69. The chuck plate 69 is fixed to the right end portion of the output shaft 18 by the screw 28. The needle thread 6 is wound around the thread take-up reel 69 by one to two turns.

The thread tension motor 16 applies tension to the thread 6 by rotating the thread tension disk 69 via the output shaft 18. The clamp motor 16 is a two-phase bipolar pulse motor. The clamp motor 16 includes a plurality of coils 33 (see fig. 3). The plurality of coils 33 are arranged along the rotational direction of the output shaft 18. The number of coils 33 in the present embodiment is four. The sewing machine 1 can supply current to each coil 33 bidirectionally. The sewing machine 1 controls a rotation angle (rotation position) of the output shaft 18 by an electromagnetic force generated by the plurality of electrically energized coils 33. The encoder 21 detects the rotation angle of the output shaft 18. A code wheel of an encoder 21 is fixed to a left end portion of the output shaft 18 and inside the arm portion 4.

As shown in fig. 4, the sewing machine 1 has a thread cutting device 59, and the thread cutting device 59 can cut the thread below the needle bar 11. The thread cutting device 59 is a well-known device that is located above the shuttle drive mechanism and in the vicinity of the needle receiving aperture of the needle board 26. The thread cutting device 59 has a cutter 58 and an electromagnetic element 57. The cutter 58 can be driven by the electromagnetic element 57 to cut the upper thread 6 and the lower thread 9. The electromagnetic element 57 can be driven in response to input of a tangent signal.

Referring to fig. 4, an electrical structure of the sewing machine 1 is explained. The control device 30 of the sewing machine 1 has a CPU 91. The CPU91 controls the operation of the sewing machine 1 including the sewing mechanism 12 and the thread cutting device 59. The CPU91 is connected to a ROM92, a RAM93, a storage device 94, and an I/O interface (hereinafter referred to as I/O) 45. The ROM92 stores programs and the like for executing various processes such as a sewing process (see fig. 8) described later. The RAM93 is used to temporarily store various values. Storage device 94 is non-volatile. The storage device 94 stores sewing data for forming a stitch 98 on a cloth 99. The storage device 94 stores a first relational expression and a second relational expression, which will be described later.

The thread cutting timing is a timing for cutting the upper thread 6 and the lower thread 9 at the end of sewing and driving the electromagnetic element 57. The sewing period is a period in which the sewing machine 1 sews a stitch, that is, a period in which the upper shaft 15 rotates one turn. As shown in fig. 7, the period during which the sewing machine 1 sews a stitch is a period from the take-up lever top dead center, which is the upper end of the movable range, to the take-up lever bottom dead center, which is the lower end of the movable range, and then to the take-up lever top dead center, and this period substantially coincides with a period corresponding to the range of 60 degrees to 420 degrees of the rotation angle of the upper shaft 15. The sewing period of the sewing machine 1 includes a shuttle catching period L1 and a thread take-up lever lifting period L2. The shuttle catching period L1 is a period during which the hook tip 36 catches the thread 6. The shuttle capture period L1 exists once during the sewing of a stitch. The shuttle catching period L1 is a period from "the hook of the upper thread by the hook means hooking the upper thread 6 by the hook tip 36" to "the detachment of the upper thread from the shuttle" in which the upper thread 6 is detached from the shuttle 39 after passing around the shuttle 39. The thread take-up lever lifting period L2 is a period in which the upper thread 6 is lifted by the thread take-up lever 51 starting from the "upper thread off shuttle". The thread take-up lever lifting period L2 is a period from "the upper thread is disengaged from the shuttle" until the thread take-up lever 51 reaches the thread take-up lever top dead center. The upper thread supply amount is increased in the take-up lever lifting period L2 during sewing. The CPU91 determines the thread cutting timing, the sewing period, the shuttle catching period L1, and the thread take-up lever lifting period L2, respectively, based on the rotation angle of the upper shaft 15 based on the detection result of the encoder 27A.

The first relational expression and the second relational expression are used when controlling the driving of the clamp motor 16. The first relational expression is an expression that relates the electric angle to the a-phase current flowing to the a-phase that is one phase in the clamp motor 16. The second relational expression is an expression that relates the phase B current flowing to the phase B, which is another phase in the clamp motor 16, to the electrical angle. As shown in fig. 5, two sinusoids having phases shifted from each other by 90 degrees are shown in the graph representing the a-phase current and the B-phase current. The electrical angle of 360 degrees in the present embodiment corresponds to the mechanical angle of 7.2 degrees. The CPU91 controls the driving of the clamp motor 16 so that the phase difference of the output shaft 18 reaches a target value. The phase difference of the output shaft 18 is an absolute value of a difference between a reference phase as a reference of the output shaft 18 and a rotational angle phase of the output shaft 18. The sewing machine 1 maintains the tension of the upper thread 6 at a predetermined tension by maintaining the phase difference of the output shaft 18 at a predetermined target value.

The I/O45 is connected to the drive circuits 81 to 86 and the electromagnetic element 57. The drive circuit 81 is connected to the main motor 27. The drive circuit 82 is connected to the swing motor 41. The drive circuit 83 is connected to the moving motor 42. The drive circuit 84 is connected to the cloth pressing motor 43. The swing motor 41, the traveling motor 42, and the cloth pressing motor 43 are pulse motors. An encoder 27A is provided on an output shaft of the main motor 27, an encoder 41A is provided on an output shaft of the swing motor 41, an encoder 42A is provided on an output shaft of the traveling motor 42, and an encoder 43A is provided on an output shaft of the cloth pressing motor 43. The encoder 27A detects the rotational position of the output shaft of the main motor 27 and outputs the detected rotational position to the CPU91 via the I/O45, the encoder 41A detects the rotational position of the output shaft of the swing motor 41 and outputs the detected rotational position to the CPU91 via the I/O45, the encoder 42A detects the rotational position of the output shaft of the shift motor 42 and outputs the detected rotational position to the CPU91 via the I/O45, and the encoder 43A detects the rotational position of the output shaft of the cloth pressing motor 43 and outputs the detected rotational position to the CPU91 via the I/O45. The CPU91 acquires the detection result of the encoder 27A and sends a control signal to the drive circuit 81, the CPU91 acquires the detection result of the encoder 41A and sends a control signal to the drive circuit 82, the CPU91 acquires the detection result of the encoder 42A and sends a control signal to the drive circuit 83, and the CPU91 acquires the detection result of the encoder 43A and sends a control signal to the drive circuit 84. Therefore, the CPU91 can control the driving of the main motor 27, the swing motor 41, the traveling motor 42, and the cloth pressing motor 43. In the following, the main motor 27, the swing motor 41, and the travel motor 42 will be collectively referred to as a drive motor.

The drive circuit 85 is connected to the clamp motor 16. The encoder 21 outputs the rotational position of the output shaft 18 of the thread tension motor 16 as a detection result to the CPU 91. The CPU91 controls the clamp motor 16 by sending a control signal to the drive circuit 85. The control method of the thread tension motor 16 will be described later.

The drive circuit 86 is connected to the display unit 48 in the operation unit 46. The CPU91 sends a control signal to the drive circuit 86 to display various information on the display unit 48. The operation knob 47 in the operation section 46 outputs the detected various information to the CPU91 via the I/O45. The pedal 38 outputs the detection result to the CPU91 via the I/O45. The CPU91 acquires the operation direction and the operation amount for the pedal 38 indicated by the detection result of the pedal 38.

With reference to fig. 6A to 6D, an outline of the operation of the sewing machine 1 will be described. The cloth 99 is placed on the cloth feeding plate and the needle plate 26, and the cloth 99 is pressed between the presser foot 24 and the cloth feeding plate by the presser foot 24. The main motor 27, the traveling motor 42, and the swing motor 41 are driven in synchronization with each other. The press arm 23 and the cloth feeding plate move back and forth with the driving of the moving motor 42, and oscillate back and forth in the left-right direction with the driving of the oscillating motor 41. Therefore, the cloth feeding device 20 moves the cloth 99 back and forth, and swings the cloth 99 back and forth in the right and left direction. When the main motor 27 is driven in synchronization with the moving motor 42 and the swing motor 41, the upper shaft 15 rotates. The needle bar up-and-down movement mechanism, the thread take-up mechanism and the rotary shuttle 39 are driven in conjunction with each other. The needle 10, which descends together with the shank 11, penetrates the cloth 99 and passes through the needle receiving hole. The upper thread 6 which has been lowered to the vicinity of the needle eye 10A below the needle receiving hole is in a ring shape (fig. 6A). The hook 36 catches the upper thread 6 in a loop shape by rotating the hook 39 clockwise in the main view. The needle 10 ascends to be separated from the cloth 99 upward, and the rotary hook 39 continues to rotate clockwise in the main view. The hook 36 pulls the endless upper thread 6 in the rotation direction to expand the diameter of the endless upper thread 6 (fig. 6B). When the upper thread 6 in a loop shape passes around the rotary hook 39 and is separated from the rotary hook 39 (fig. 6C), the upper thread 6 is interwoven with the lower thread 9. The rotating direction of the rotary hook 39 is switched to the counterclockwise direction in the main view, and the thread take-up lever 51 lifts the upper thread 6 interlaced with the lower thread 9 (fig. 6D). The upper thread 6 in a ring shape is reduced in diameter, so that the sewing machine 1 finishes sewing one needle. The sewing machine 1 performs one stitch sewing every time the upper shaft 15 rotates 360 degrees. The sewing machine 1 repeats the above operations to form a stitch 98 on the fabric 99.

The sewing process will be described with reference to fig. 8. The sewing process is a process in which the sewing machine 1 sews the fabric 99. When the operator operates the operation knob 47 to start power supply to the sewing machine 1, the CPU91 reads out a program from the ROM92 to the RAM93 to execute sewing processing.

The CPU91 executes initialization processing (S1). The CPU91 reads various setting values from the storage device 94 into the RAM 93. In S1, the CPU91 acquires the rotation angle of the output shaft 18 of the thread tension motor 16 based on the detection result of the encoder 21. This rotational angle is the reference phase of the output shaft 18 in the initial state, and is stored in the RAM 93. The CPU91 acquires the predetermined tension to be applied to the face line 6 by acquiring the detection result of the operation knob 47 (S2). The operator operates the operation knob 47 to input the tension to be applied to the face line 6. When the operator operates the operation knob 47 and inputs a specific numerical value as a predetermined tension, the CPU91 acquires the input predetermined tension. The CPU91 may acquire an initial value as the predetermined tension. The CPU91 acquires the prescribed amount input by the operation knob 47 (S3). The predetermined amount is a predetermined supply amount of the upper thread 6 to be supplied between the thread take-up reel 69 and the stitch 98 at the same timing as the thread cutting timing. The operator operates the operation knob 47 to input a predetermined amount. When the operator operates the operation knob 47 to input a specific numerical value as a predetermined amount, the CPU91 acquires the input predetermined amount. The CPU91 may acquire an initial value as a predetermined amount. The CPU91 calculates a target value corresponding to the predetermined tension acquired in S2 (S4). The upper thread tension has a correlation with the torque generated by the thread tension motor 16. The target value is the phase difference of the output shaft 18 when the value of the face line tension calculated based on the correlation stored in the storage device 94 reaches a predetermined tension. The CPU91 calculates the rotation amount of the output shaft 18 required to supply the predetermined amount of the upper thread 6 acquired in S3 between the thread take-up reel 69 and the stitch 98 (S5). The CPU91 calculates the rotation amount of the output shaft 18 based on the predetermined amount acquired in S3 based on the relational expression between the predetermined amount and the rotation amount of the output shaft 18. The relation is stored in the storage device 94.

The CPU91 determines whether or not a sewing start instruction of the sewing machine 1 is detected (S6). The operator inputs a sewing start instruction by operating the operation knob 47 or the pedal 38. The CPU91 is in a standby state before detecting the sewing start instruction (S6: NO). During standby, the operator places the cloth 99 on the needle plate 26 and the cloth feeding plate. When the sewing start instruction is input by the operator after the cloth 99 is placed (S6: yes), the CPU91 controls the drive of the cloth pressing motor 43 to lower the presser foot 24 (S7). The presser foot 24 sandwiches the cloth 99 between the presser foot 24 and the cloth feed plate. The CPU91 determines the energization types corresponding to the respective coils 33 and energizes them (S8). The energization types include a phase-a current and a phase-B current. The CPU91 determines the energization type based on the first relational expression, the second relational expression, and the rotation angle of the output shaft 18 acquired in S1. The CPU91 performs energization on the plurality of coils 33 in accordance with the determined energization type.

CPU91 controls the driving of the driving motor to form stitch 98 on fabric 99 (S9). The needle bar 11, the rotary hook 39 and the cloth feeding table 37 are operated in synchronization with each other. The CPU91 executes the clamp motor driving process (S10). The wire clamping motor driving process is a process of controlling the tension of the wire. As shown in fig. 9, the CPU91 acquires the rotation angle of the output shaft 18 of the clamp motor 16 based on the detection result of the encoder 21 (S21). The CPU91 determines whether the comparison value is greater than the threshold value (S22). The comparison value is obtained by subtracting the target value from the phase difference of the output shaft 18. The CPU91 calculates a comparison value using the rotation angle of the output shaft 18 acquired in S21, the target value calculated in S4, and the reference phase stored in the RAM 93. The threshold value is determined according to the target value and is a value greater than 0. When the sewing operation is started by the sewing machine 1, the current of the energization type determined in S8 flows to the plurality of coils 33. When the sewing operation is started by the sewing machine 1, the phase difference is theoretically 0 (S22: No). At this time, the CPU91 ends the clamp motor driving process.

The CPU91 determines whether or not a sewing end instruction of the sewing machine 1 is detected based on the detection result of the operation knob 47 (S11). The sewing end instruction indicates that the operation of the pedal 38 by the operator is stopped or the sewing is ended based on the sewing data. When the CPU91 determines that the sewing end instruction is not detected (S11: no), the CPU91 shifts the process to S10 and repeatedly executes S10 and S11. The output shaft 18 is gradually rotated so that the upper thread 6 is successively fed in the feeding direction, and the comparison value is increased to increase the tension of the upper thread.

After a predetermined number of times of the thread clamping motor driving processing has elapsed since the sewing processing (S10), the comparison value becomes larger than the threshold value (S22: YES). At this time, the upper thread tension is greater than the prescribed tension acquired in S2. The CPU91 determines the energization types for the plurality of coils 33 (S23). The CPU91 determines an energization type capable of eliminating the difference between the phase difference of the output shaft 18 and the target value, based on the first relational expression, the second relational expression, and the rotation angle of the output shaft 18 acquired in S21 (S23). The CPU91 switches the energization type being performed for the plurality of coils 33 to the energization type specified in S23 (S24). The output shaft 18 rotates, and the upper thread tension is returned to the predetermined tension acquired in S2. At this time, the CPU91 rewrites the RAM93 with the rotational angle of the output shaft 18 after rotation as a reference phase. The CPU91 ends the wire clamp motor drive processing. The CPU91 determines the energization type based on the detection result of the encoder 21 every time S23 is executed (S23), and switches the energization types of the plurality of coils 33 (S24). S10 is repeatedly executed by the CPU91 so that the sewing machine 1 maintains the upper thread tension at the prescribed tension acquired in S2.

When the CPU91 determines that the sewing end instruction has been detected (S11: yes), the CPU91 determines whether the thread cutting timing is the thread cutting timing based on the output value of the encoder 27A (S12). When the rotation angle of the upper shaft 15 by the encoder 27A is a predetermined value (for example, 250 degrees), the CPU91 determines that it is the tangent timing. The timing of the tangent is set to a predetermined timing in the shuttle catching period L1 in fig. 7, for example. When the CPU91 determines that it is not the thread cutting timing (S12: no), the CPU91 executes the same pinch motor driving process as in S10 (S17), and then returns the process to S12.

When the CPU91 determines that the timing is the thread cutting timing (yes in S12), the CPU91 drives the solenoid 57 to start controlling the driving of the thread cutting device 59 (S13). The CPU91 controls the drive circuit 85 to drive the pinch motor 16, monitors the output value of the encoder 21, and rotates the output shaft 18 by the rotation amount calculated in S5 (S14). The CPU91 controls the driving of the supply mechanism 60 at the same timing as the driving of the thread cutting device 59, and supplies a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the stitch 98. In the case of the conventional sewing machine, the "same timing for controlling the driving of the thread cutting device 59" may be the same timing as the timing for releasing the thread clamp 69 to relax the tension of the upper thread, may be during the driving of the thread cutting device 59, or may be after the driving of the thread cutting device 59 is completed. The CPU91 supplies a predetermined amount of the needle thread 6 between the thread tension disc 69 and the stitch 98 during a period L3 (see fig. 7), for example, a period L3 is a period from the time when the needle bar bottom dead center is reached to immediately before the needle thread 6 is cut by the thread cutting device 59. When the thread tension motor 16 is driven, the thread tension disc 69 rotates in the feeding direction of the upper thread 6 (clockwise direction in the right view), and the upper thread 6 is sequentially discharged. Therefore, the feeding mechanism 60 feeds a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the thread take-up lever 51 until the upper thread 6 is cut by the thread cutting device 59.

After the upper thread 6 is supplied by the supply mechanism 60, the driving of the thread cutting device 59 is controlled in S13, and the thread cutting device 59 cuts the upper thread 6 and the lower thread 9 by sandwiching them between the cutter blades 58. At this time, the upper thread tension is sufficiently smaller than that before the upper thread 6 is supplied by the supply mechanism 60 due to the predetermined amount of the upper thread 6 which has been supplied between the thread take-up reel 69 and the thread take-up lever 51. The CPU91 stops driving of the drive motor (S15). The CPU91 controls the driving of the cloth pressing motor 43 to raise the presser foot 24 (S16), and then ends the sewing process. The cloth 99 can be taken off from the sewing machine 1.

In the above embodiment, the sewing mechanism 12 is an example of a sewing portion of the present invention, the upper thread 6 is an example of a suture thread of the present invention, the thread-clamping motor 16 is an example of an actuator (motor) of the present invention, the supply mechanism 60 is an example of a supply portion of the present invention, the control device 30 is an example of a control portion of the present invention, and the operation knob 47 is an example of an input portion of the present invention. The CPU91 executing S9 is an example of the sewing control unit of the present invention. The CPU91 when S13 is executed is an example of the thread cutting control unit. The CPU91 executing S14 is an example of the supply control unit of the present invention. The CPU91 executing S15 exemplifies the stop control unit of the present invention. The CPU91 executing S3 exemplifies the thread amount acquiring unit of the present invention. The CPU91 executing S5 is an example of the calculation unit of the present invention.

The sewing machine 1 of the above embodiment controls the driving of the supply mechanism 60 at the same timing as the driving of the thread cutting device 59, and supplies the upper thread 6 of a predetermined amount between the thread tension disc 69 and the stitch 98 (S14). The upper thread tension when the upper thread 6 is cut by the thread cutting device 59 is stabilized by the predetermined amount of the upper thread 6 supplied. Therefore, the sewing machine 1 can reduce the unevenness of the upper thread residual amount after the upper thread 6 is cut by the thread cutting device 59, and can prevent the sewing failure from occurring at the start of the next sewing.

The sewing machine 1 of the above embodiment applies tension to the upper thread 6 by rotating the thread tension disc 69 via the output shaft 18 by the thread tension motor 16 having the output shaft 18 rotatably supporting the thread tension disc 69. The sewing machine 1 controls the drive of the thread take-up motor 16 at the same timing as the control of the drive of the thread cutting device 59 in S13, rotates the thread take-up reel 69 in the feed direction of the upper thread 6, and feeds the upper thread 6 of the predetermined amount obtained in S3 between the thread take-up reel 69 and the stitch 98 (S14). The sewing machine 1 can rotate the thread take-up reel 69 by controlling the driving of the thread take-up motor 16, and supply a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the stitch 98. Since the sewing machine 1 rotates the thread take-up reel 69 by the motor, a predetermined amount of the upper thread 6 can be accurately supplied between the thread take-up reel 69 and the stitches 98 in a relatively short time. The sewing machine 1 can simplify the structure near the feed path compared to the case where the feed mechanism 60 is provided near the feed path of the upper thread 6 independently of the thread tension disk 69.

The sewing machine 1 has an operation knob 47 for inputting a prescribed amount. The sewing machine 1 acquires the predetermined amount inputted by the operation knob 47 (S3). The sewing machine 1 calculates the rotation amount of the output shaft 18 required to supply the predetermined amount of the upper thread 6 acquired in S3 between the thread take-up reel 69 and the stitch (S5). The sewing machine 1 controls the driving of the thread take-up motor 16 at the same timing as the driving of the thread cutting device 59, and rotates the output shaft 18 by the rotation amount calculated in S5, thereby supplying a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the stitch 98 (S14). The sewing machine 1 can feed a predetermined amount of the upper thread 6 inputted by the operation knob 47 between the thread take-up reel 69 and the stitch 98. The operator can set an optimum predetermined amount in consideration of the sewing conditions.

The sewing machine 1 supplies a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the stitch 98 at the same timing as the drive of the thread cutting device 59 is controlled and before the upper thread 6 is cut. Compared to the case where the predetermined amount of the upper thread 6 is supplied between the thread tension disk 69 and the stitch 98 at the same timing of controlling the driving of the thread cutting device 59 and after the upper thread 6 is cut, the sewing machine 1 can more reliably stabilize the upper thread tension when the upper thread 6 is cut by the thread cutting device 59 by using the supplied predetermined amount of the upper thread 6.

The sewing machine 1 supplies a predetermined amount of the upper thread 6 between the thread take-up reel 69 and the thread take-up lever 51 in the period L3. As shown in fig. 7, the sewing machine 1 can supply a predetermined amount of the upper thread 6 between the thread tension disc 69 and the stitch 98 when the upper thread tension is lower than the upper thread tension when the upper thread 6 is lifted by the thread take-up lever 51 (the thread take-up lever lifting period L2). The sewing machine 1 can suppress the unevenness of the upper thread tension when the upper thread is pulled up by the thread take-up lever 51 after the predetermined amount of the upper thread 6 is supplied between the thread take-up reel 69 and the thread take-up lever 51.

The present invention is not limited to the above-described embodiments. The sewing machine may be a sewing machine for a flat seam, a buttonhole sewing machine, or the like, or a home sewing machine or an embroidery sewing machine. The feed mechanism 60 in the sewing machine may be provided in the vicinity of the feed path of the upper thread 6 independently of the thread tension disk. The sewing machine may be provided with a feeding-out portion for feeding out the upper thread between the thread take-up lever and the thread take-up reel. The supply mechanism may be a mechanism that: the suture is pinched between the driven roller and the drive roller, and the drive roller is continuously rotated to sequentially pay out the suture between the pinch roller and the stitch. The supply mechanism may be a mechanism that: the rod-shaped member in contact with the upper thread is moved to change the length of the path of the upper thread, thereby sequentially releasing the thread between the thread clamping disk and the stitch. The actuator of the supply mechanism may be a single-phase motor, a three-phase or more motor, various electric motors such as a DC motor and a coreless motor, an electromagnetic element, a cylinder, or the like. The input unit may be omitted from the sewing machine, or the sewing machine may have an input unit having another configuration such as a dial input unit and a touch panel. The supply mechanism may supply the bobbin thread between the thread take-up reel and the stitches by the power of the driver, or the thread cutting device may cut only the bobbin thread. The present invention may be applied to a lower thread cutting mechanism of a round-head keyhole sewing machine or the like, for example. The thread cutting device 59 may cut only the upper thread 6 without cutting the lower thread 9. Instead of the electromagnetic element 57, the thread cutting device 59 may have a motor or the like.

The program for executing the sewing process in fig. 8 may be stored in a storage device of the sewing machine before the sewing machine executes the program. The program acquisition method, the acquisition path, and the device for storing the program may be appropriately changed, respectively. Alternatively, the sewing machine may receive a program to be executed by the processor from another device by wire or wireless communication, and store the program in the storage device. Other devices include, for example, computers and servers connected via a network. The storage device of the sewing machine may be a storage device such as an HDD or an SSD.

The steps in the sewing process in fig. 8 are not limited to the example executed by the CPU91, and some or all of the processes may be executed by another electronic device (for example, ASIC). Each step in the above-described processing may be distributed processing by a plurality of electronic devices (for example, a plurality of CPUs). The order of the steps in the sewing process of the above embodiment can be changed as necessary, and the steps can be omitted or added. The present invention may be embodied as follows: the functions of the above embodiments are realized by executing a part or all of the actual processing by an OS or the like operating on the position specifying device in accordance with an instruction from the control unit of the sewing machine.

The thread may be fed by a feeding mechanism before the thread cutting device is driven. The sewing machine may control the driving of the feeding mechanism to feed a predetermined amount of the thread between the take-up lever and the stitch. The sewing machine may omit the processes of S3 and S5, and rotate the output shaft of the thread tension motor by a preset rotation amount in S14. The sewing machine may automatically set a predetermined amount according to the thickness of the cloth, the stitch width, and the like. It is also possible that the sewing machine omits S2, S4, S8, S10, S17 as appropriate.

Claims

1. A sewing machine (1) has:

a sewing part (12) having a needle bar (11) to which a needle (10) is attached and which is capable of moving up and down, the sewing part being capable of forming a stitch (98) on a fabric using the needle;

a suture thread take-up reel (69) around which a suture thread (6) is wound;

a thread cutting device (59) capable of cutting the suture below the needle shaft; and

a control part (30) for controlling the driving of the sewing part and the thread cutting device,

the sewing machine is characterized in that the sewing machine is provided with a sewing machine,

the sewing machine is provided with a supply part (60) which is provided with a driver and can supply the suture between the thread clamping disk and the stitch by using the power of the driver,

the control part functions as a sewing control part, a thread cutting control part, a supply control part and a stop control part,

the sewing control part is used for controlling the driving of the sewing part and forming the stitch on the cloth,

a thread cutting control unit for starting control of driving of the thread cutting device;

the supply control part is used for controlling the driving of the supply part at the same time when the thread cutting control part controls the driving of the thread cutting device so as to supply a specified amount of the thread between the thread clamping disc and the stitches,

the stop control part is used for stopping the driving of the sewing part controlled by the sewing control part after the supply control part controls the driving of the supply part to supply the suture between the thread clamping disk and the stitch.

2. The sewing machine of claim 1,

the driver is a motor (16) having an output shaft (18) for rotatably supporting the suture clamping disc, and the motor is used for applying tension to the suture by rotating the suture clamping disc through the output shaft,

the supply control unit controls the driving of the motor at the same timing when the thread cutting control unit controls the driving of the thread cutting device, so that the thread tension disk rotates in the thread supply direction and the predetermined amount of the thread is supplied between the thread tension disk and the stitch.

3. The sewing machine of claim 2,

the sewing machine also has an input part (47) for inputting the specified amount to be supplied between the thread clamping disk and the stitch,

the control section also functions as a thread amount acquisition section and a calculation section,

the thread amount acquiring unit acquires the predetermined amount input by the input unit,

a calculating section for calculating a rotation amount of the output shaft of the motor required to supply the specified amount of the suture obtained by the thread amount obtaining section between the thread nipping tray and the stitch,

the supply control unit controls the driving of the motor to rotate the output shaft by the rotation amount calculated by the calculation unit at the same timing as the timing at which the driving of the thread cutting device is controlled.

4. Sewing machine as in any of claims 1 to 3,

the supply control unit supplies the predetermined amount of the suture between the suture holding tray and the stitches before the suture is cut at the same timing of controlling the driving of the thread cutting device.