CN110656447A

CN110656447A - Sewing machine

Info

Publication number: CN110656447A
Application number: CN201910566539.6A
Authority: CN
Inventors: 竹村徹; 庄锦伟
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-06-29
Filing date: 2019-06-27
Publication date: 2020-01-07
Anticipated expiration: 2039-06-27
Also published as: CN110656447B; JP2020000731A

Abstract

The invention relates to a sewing machine, which can restrain the upper thread from tangling and bunching during the sewing. The sewing machine has a sewing mechanism and a thread clamping mechanism. The sewing mechanism is provided with a needle. The needle has an eye through which an upper thread can be inserted to hold the upper thread. The sewing mechanism sews the fabric by moving the needle up and down. The wire clamping mechanism is provided with a wire clamping disc and a wire clamping motor. The thread take-up motor rotates a thread take-up reel on which an upper thread is wound. When the sewing mechanism sews the cloth, the CPU of the sewing machine controls the thread clamping motor to rotate the thread clamping disk. At this time, the CPU moves the upper thread in the retracting direction by a predetermined amount based on the amount of the upper thread passing through the eye of the needle. The retracting direction is the reverse of the direction of supplying the upper thread to the needle eye.

Description

Sewing machine

Technical Field

The present invention relates to a sewing machine.

Background

A sewing machine capable of adjusting the length of an upper thread threaded on a needle is known. The sewing machine described in japanese laid-open patent publication No. 1994 190172 includes, in order from the upstream side of the upper thread supply path, a first gripper, a thread pulling section, a second gripper, and a thread gripper. The first holding device and the second holding device are both: the upper thread is held when the upper thread is in an open state and released when the upper thread is in a closed state. The thread pulling section can pull the upper thread from the first thread tension device side. The thread clamping device is provided with a thread taking-up spring and a stop body. The thread take-up spring can swing. The stop body is clamped with a stop driver of the sewing machine. The sewing machine switches the first holding device and the second holding device to an open state and a closed state, and pulls the upper thread by the thread pulling section, and then the sewing machine performs sewing. At this time, the second gripping device and the stopper driver are in an open state, and the upper thread is gripped by the second gripping device. The stopper is moved to a position where the thread take-up spring is inhibited from swinging, thereby inhibiting the upper thread from being sequentially paid out from the thread tension caused by the swinging of the thread take-up spring. The sewing machine consumes the upper thread at the needle point in the starting sewing.

Since the sewing machine performs sewing by consuming the upper thread at the needle point in the starting sewing, the upper thread at the needle point needs to have a certain length before sewing. When the length of the needle thread at the needle point is long, the needle thread pulled under the fabric becomes long. Thus, there is the following possibility: the upper thread at the needle tip is tangled and lumped under the cloth before being worn out in the seam, so-called bird's nest (the material of the hive of japanese: bird) occurs.

Disclosure of Invention

The invention aims to provide a sewing machine which can prevent upper threads from being tangled and conglobated under a cloth when sewing.

The sewing machine of claim 1 comprises: a sewing part having a needle bar equipped with a machine needle, the needle bar being capable of moving up and down, the sewing part being capable of sewing a fabric using the machine moving up and down; a wire clamping mechanism having: a thread take-up reel on which an upper thread is wound; and a driving unit for rotating the thread clamping disk, wherein the thread clamping mechanism adjusts the supply amount of the surface thread to the needle by the rotation of the thread clamping disk; a sewing control part for sewing the cloth by controlling the sewing part; and a thread adjusting control unit that controls the drive unit to control a supply amount of the upper thread to the needle when the sewing control unit controls the fabric to be sewn, wherein the thread adjusting control unit includes a thread take-up control unit that controls the drive unit to move the upper thread in a take-up direction that is a reverse of a supply direction of the upper thread to the needle by a predetermined amount based on an amount of the upper thread that is threaded on the needle when the sewing control unit controls the fabric to be sewn. By controlling the driving part by the thread take-up control part, the amount of the upper thread left on the cloth at the time of starting sewing can be reduced. Therefore, the sewing machine can prevent the upper thread from being tangled and conglomerated under the cloth when sewing.

In the sewing machine according to claim 2, when the sewing control unit controls the sewing of the fabric, the thread take-up control unit may control the drive unit a plurality of times so that the upper threads are moved by the predetermined amount in total by the plurality of movements. The upper thread take-up section moves the upper thread a plurality of times, so that the upper thread is less likely to be disengaged from the needle, i.e., disengaged, than the case where the upper thread is moved only once. Therefore, the sewing machine can restrain the thread off when sewing.

In the sewing machine according to claim 3, the thread take-up control unit may move the upper thread in the take-up direction at least once after the needle penetrates the fabric for the first time from the start of sewing by the sewing control unit and before the needle penetrates the fabric for the second time. The thread separation is easily caused by the friction between the upper thread held by the needle moving up and down and the cloth. The upper thread is moved after the needle penetrates the cloth for the first time and before the needle penetrates the cloth for the second time. Therefore, the sewing machine can restrain the thread off when the needle penetrates the cloth for the first time.

In the sewing machine according to claim 4, the sewing section may include a thread take-up lever that moves up and down in synchronization with the up and down movement of the needle bar to lift the upper thread, the thread adjustment control section may include a determination section that determines whether or not the thread take-up lever is lifting the upper thread, and the thread take-up control section may move the upper thread when the determination section determines that the thread take-up lever is lifting the upper thread. When the take-up lever lifts up the upper thread, the upper thread is easily stretched. The upper thread withdrawing control part rotates the thread clamping disc in the process that the take-up lever lifts the upper thread, so the upper thread is easier to move towards the withdrawing direction. Therefore, the sewing machine can further suppress the occurrence of the upper thread being tangled and lumped under the cloth at the time of starting sewing.

In the sewing machine according to claim 5, the sewing machine may include a needle number input unit that can input a needle number for limiting the start of sewing by the sewing control unit, and the thread take-up control unit may move the upper thread by the predetermined amount within the needle number input by the needle number input unit. The sewing machine can limit the sewing period according to the number of needles input by the input part. Therefore, the sewing machine can diversify the mode of moving the upper thread by the thread take-up control part.

In the sewing machine according to claim 6, the sewing machine may further include a timing input unit that can input a timing at which the upper thread is moved by the thread take-up control unit, and the thread take-up control unit may move the upper thread in the take-up direction at the timing input by the timing input unit. The timing of the movement of the upper thread by the thread take-up control section is changed in accordance with the timing inputted by the timing input section. Therefore, the sewing machine can diversify the mode of moving the upper thread by the thread take-up control part.

In the sewing machine according to claim 7, the sewing machine may include a movement amount input portion capable of inputting the predetermined amount by the movement amount input portion, and the thread take-up control portion may move the upper thread by the predetermined amount inputted by the movement amount input portion. The amount of movement of the upper thread by the thread retraction control section is changed in accordance with the predetermined amount inputted by the movement amount input section. Therefore, the sewing machine can diversify the mode of moving the upper thread by the thread take-up control part.

In the sewing machine according to claim 8, the thread adjusting control unit may include a thread supply control unit that moves the upper thread in the supply direction before the thread take-up control unit moves the upper thread and before the needle penetrates the fabric for the first time, and the thread take-up control unit may move the upper thread by the predetermined amount after the needle penetrates the fabric for the first time. The upper thread is moved in the feeding direction before the upper thread is moved by the thread take-up control section. Therefore, the sewing machine can prevent the upper thread which is threaded on the needle from being insufficient when the needle penetrates the cloth for the first time, thereby reliably inhibiting the thread from being off.

Drawings

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

Fig. 2 is a sectional view of the thread tension 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 an explanatory diagram showing a needle bar movement curve, a thread take-up lever thread amount curve, a shuttle thread amount curve, and a feed amount of the upper thread 6.

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

Fig. 7 is a flowchart of the sewing process.

Fig. 8 is a flowchart of the sewing process connected to fig. 7.

Fig. 9 is a front view of the needle 10 and the cloth 99 before sewing starts.

Fig. 10 is a flowchart of a general process.

Fig. 11 is a front view of the needle 10 when it first penetrates the cloth 99.

Fig. 12 is a front view of the needle 10 which is moved to a position above the cloth 99 after first penetrating the cloth.

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 5, 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 input unit 47. The display unit 48 can display various information. The input unit 47 can detect various information input by the operator. The input section 47 includes a power button.

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 on a cloth 99 by the needle 10 moving up and down. 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-down movement mechanism, a shuttle mechanism 40, 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 a curved portion that exhibits a curve at a position deviated from the axis of the front end portion and the rear end portion 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 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, and the thread take-up lever 51 is provided on 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 into the upper thread insertion hole (see fig. 6A). The needle thread 6 is sequentially fed from the needle thread supply source and fed to the needle thread punch of the thread take-up lever 51 via a thread take-up 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. 9). The upper thread 6 perforated by the upper thread of the thread take-up lever 51 can be inserted into the needle eye 10A, 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 mechanism 40 is provided inside the housing unit 2. The shuttle mechanism 40 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. The rotating shuttle 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. As shown in fig. 6A, the rotary hook 39 has a hook tip 36. 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, and the bobbin thread 9 fed out from the bobbin can be led to the outside by the lead-out portion 34.

The sewing machine 1 has a thread cutting mechanism inside the bed section 2. The thread cutting mechanism includes a fixed blade, a movable blade, and a thread cutting electromagnetic element 161 (see fig. 4). The movable blade is connected to a tangent electromagnetic element 161. The movable knife is moved by driving the thread cutting solenoid 161, and the upper thread 6 and the lower thread 9 are cut by the thread cutting mechanism.

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 rack shaft 22 has a distal end connected to an upper end of the swing shaft. The rear end of the rack shaft 22 is located inside the column part 3. The moving motor 42 is provided inside the column part 3, and the moving motor 42 can move the rack shaft 22 forward and backward. 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 has a thread tension mechanism 60 on the right wall portion 5A. The thread tension mechanism 60 includes a thread tension cylinder 62, a thread tension holder 63, a thread take-up spring 65, a thread tension motor 16, a thread tension disc 69, and an encoder 21 (see fig. 4). The thread clamping mechanism 60 is capable of feeding the thread between the thread clamping disc 69 and the stitch 98 by the power of the thread clamping 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 thread take-up motor 16 is fixed inside the arm part 4. 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 wire chuck 69 is fixed to the right end of the arm portion 4 via a 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 this 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. The rotation direction of the output shaft 18 (i.e., the thread take-up reel 69) is switched by the thread take-up motor 16, whereby the upper thread 6 can be moved in the feeding direction and the retracting direction. The feeding direction is a direction in which the upper thread 6 is fed toward the eye 10A of the needle 10. The withdrawal direction is the reverse of the feed direction.

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 can control the operation of the sewing machine 1 including the sewing mechanism 12 and the thread tension motor 16. 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. 7) described later. The RAM93 is used to temporarily store various values. Memory device 94 is non-volatile, and memory device 94 stores sewing data for forming stitches 98 in fabric 99. The storage device 94 stores a first relational expression and a second relational expression. When controlling the driving of the clamp motor 16, a first relational expression and a second relational expression are used, which relate the electric current flowing through each phase of the clamp motor 16 to the electric angle. The CPU91 controls the driving of the clamp motor 16 so that the phase difference of the output shaft 18 reaches a predetermined target value (hereinafter referred to as a target value) larger than 0. 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. Hereinafter, the rotational angle phase of the output shaft 18 is referred to as a pinch rotational angle.

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. 5, the period during which the sewing machine 1 of the present embodiment sews a needle is a period during which the thread take-up lever 51 starts from the upper end of the movable range, i.e., the top dead center, passes through the lower end of the movable range, i.e., the bottom dead center, and then returns to the top dead center, and this period substantially coincides with a period corresponding to a range of 60 degrees to 420 degrees of the rotation angle of the upper shaft 15. Hereinafter, the rotation angle of the upper shaft 15 is referred to as an upper shaft angle. The upper shaft angle is a value based on the detection result of the encoder 27A of the main motor 27. In fig. 5, the period during which the thread take-up lever 51 lifts the upper thread 6, i.e., the period during which the thread take-up lever is lifted, is a period corresponding to the range of 310 to 420 degrees of the upper shaft angle. The needle bar motion curve of the needle bar 11, the shuttle thread amount curve of the rotating shuttle 39, and the thread take-up lever thread amount curve of the thread take-up lever 51 are each set to one cycle during the sewing of one stitch by the sewing machine 1. The upper axis angle may also have a value of 0 degrees to 359 degrees. In this case, a counter for counting the number of pins may be provided, and 1 may be added to the counter every time the upper axis angle becomes 0 degrees.

The I/O45 is connected to the drive circuits 81 to 87. 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 pinching rotation angle of the pinching motor 16 as the 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. The CPU91 sends a control signal to the drive circuit 86 to display various information on the display unit 48. The input section 47 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. The drive circuit 87 is connected to the tangent electromagnetic element 161. The CPU91 controls the driving of the tangent electromagnetic element 161 by sending a control signal to the drive circuit 87.

With reference to fig. 1 and 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. The presser foot 24 is lowered by driving the cloth pressing motor 43, and the presser foot 24 presses the cloth 99 between the presser foot 24 and the cloth feeding plate. 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. The upper shaft 15 is rotated by the main motor 27 driven in synchronization with the moving motor 42 and the swing motor 41. 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 formed in a ring shape (see 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 (see 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 (see fig. 6C), the upper thread 6 is interlaced 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 (see fig. 6D). The upper thread 6 in a ring shape is reduced in diameter, so that the sewing machine 1 finishes sewing one needle. In the present embodiment, 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. 7 to 12. The sewing process is a process in which the sewing machine 1 sews the fabric 99. Before the sewing process is started, the needle bar 11 is positioned near the upper end of the movable range, and the upper thread 6 is inserted into the needle eye 10A. For example, when the operator operates the input unit 47 to turn on the power supply of the sewing machine 1, the CPU91 reads a program from the ROM92 into the RAM93 to execute the sewing process.

As shown in fig. 7, the CPU91 executes initialization processing (S1). The CPU91 reads various setting values from the storage device 94 into the RAM 93. The CPU91 acquires the needle thread retracting amount, which is the amount of movement of the needle thread 6 in the retracting direction, based on the detection result of the input unit 47 (S3). The needle thread take-up amount is a prescribed amount based on the amount of the needle thread 6 inserted into the needle eye 10A, which is shorter than the length of the needle thread 6 actually inserted into the needle eye 10A.

The CPU91 acquires the set stitch number, which defines a predetermined number of stitches from the sewing machine 1, based on the detection result of the input unit 47 (S5). The number of sewing needles is, for example, two. The CPU91 acquires a mode (hereinafter referred to as the upper thread retracting mode) for retracting the upper thread 6 in the retracting direction at the time of sewing based on the detection result of the input section 47 (S7). The needle thread withdrawing mode includes an automatic withdrawing mode and a set withdrawing mode. In the automatic retraction mode, the sewing machine 1 retracts the upper thread 6 at the start of the thread take-up lever lifting period in the period of the number of sewing needles. In the set retraction mode, the sewing machine 1 retracts the upper thread 6 at the times and timing designated by the operator. The operator inputs any one of the automatic retraction mode and the set retraction mode using the input section 47.

The CPU91 determines whether the face line retracting mode acquired in S7 is the automatic retracting mode (S9). When the CPU91 determines that it is the automatic retraction mode (S9: yes), the CPU91 shifts the process to S15. When the CPU91 determines that the retraction mode is set (S9: no), the CPU91 acquires the needle thread retraction count, which is the number of times the needle thread 6 is moved in the retraction direction at the time of starting sewing, based on the detection result of the input unit 47 (S11). The needle thread take-back number is, for example, two times. The CPU91 acquires the needle thread retracting timing which is the timing to retract the needle thread 6 (S13). For example, the CPU9 displays on the display unit 48 the range of the vertical axis angle corresponding to the number of stitches obtained in S5. The operator inputs an upper axis angle corresponding to a desired needle thread retraction timing by the input unit 47 while looking at the display unit 48. Therefore, the needle thread retraction timing is a timing within the number of sewing needles acquired in S5. The timing of the needle thread retraction is, for example, 330 degrees or 690 degrees at the upper axis angle. The corresponding time of the two upper shaft angles is in the lifting period of the take-up lever. The upper axis angle of 330 degrees corresponds to a timing after the needle 10 penetrates the cloth 99 for the first time and before the needle penetrates the cloth for the second time. The timing when the upper axis angle is 690 degrees is after the needle 10 penetrates the cloth 99 for the second time.

The CPU91 acquires the pinching rotation angle and the upper shaft angle based on the detection results of the encoder 21 and the encoder 27A (S15). The pinching rotation angle acquired in S15 is the first reference phase (hereinafter referred to as the reference phase) of the output shaft 18 in the normal process (S35) described later.

The CPU91 acquires the set tension of the upper thread 6 based on the detection result of the input section 47 (S17). The CPU91 acquires a target value corresponding to the set tension acquired in S17 (S19). The torque generated by the thread tension motor 16 and the set tension of the upper thread 6 have a correlation with each other. 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 is a predetermined tension. The CPU91 acquires the target value by acquiring the phase difference corresponding to the set tension acquired in S17 based on the correlation stored in the storage device 94.

The CPU91 determines whether or not a sewing start instruction, which is an instruction to start sewing, is detected based on the detection result of the pedal 38 (S21). Before the operator steps on the pedal 38 (S21: NO), the CPU91 stands by. When the operator places the cloth 99 on the cloth feeding plate and then steps on the pedal 38 (yes in S21), the CPU91 controls the driving of the cloth pressing motor 43 to lower the presser foot 24 (S23). The presser foot 24 sandwiches the cloth 99 between it and the feed plate.

The CPU91 starts energization to the plurality of coils 33 (S25). The CPU91 determines the energization type based on the first relational expression, the second relational expression, the pinch rotation angle acquired in S15, and the target value acquired in S19, and starts energization to the plurality of coils 33.

The CPU91 drives the thread tension motor 16 to move the upper thread 6 in the feeding direction (S27). The length of the upper thread 6 inserted into the needle eye 10A is increased by moving the upper thread 6 in the feeding direction (arrow a1 in fig. 9). The CPU91 starts driving of the drive motor (S29). The needle bar 11, the rotary hook 39, and the cloth feeding table 37 are operated in synchronization with each other.

The CPU91 refers to the RAM93, and determines whether or not the retraction of the opposite line 6 has been completed (S30). The CPU91 stores the accumulated moving amount of the upper thread 6 in the retracting direction in S39 described later in the RAM 93. Immediately after the start of the sewing operation of the sewing machine 1, the amount of movement of the upper thread 6 in the retracting direction stored in the RAM93 is 0 (S30: no). The CPU91 determines whether the needle thread retracting mode acquired in S7 is the automatic retracting mode (S31). When the CPU91 determines that the retraction mode is set (S31: no), the CPU91 shifts the process to S33. The CPU91 determines whether the needle thread retraction timing has come (S33). The CPU91 determines whether or not the timing has come based on whether or not the upper axis angle indicated by the detection result of the encoder 27A and the upper axis angle indicated by the needle thread retracting timing acquired in S13 coincide. When the upper axis angle is less than 330 degrees (S33: NO), the CPU91 executes a normal process (S35).

As shown in fig. 10, the CPU91 acquires the pinching rotation angle based on the detection result of the encoder 21 (S61). The CPU91 determines whether the phase difference is greater than the target value based on the reference phase, the target value acquired in S19, and the wire pinching rotation angle acquired in S61 (S63). When the sewing operation is started, the reference phase is the upper axis angle obtained in S15, and the phase difference is theoretically 0 (S63: no). The CPU91 ends the normal processing, and returns the processing to the sewing processing in fig. 8.

The CPU91 determines whether or not a sewing stop instruction, which is an instruction to stop sewing, is detected based on the detection result of the pedal 38 (S43). When the operator does not step back on the pedal 38 (S43: no), the CPU91 shifts the process to S30. When the CPU91 repeatedly executes S30, S31, S33, S35, S43, the needle 10 pierces the cloth 99 (refer to fig. 11).

After the thread take-up lever 51 starts to lift the upper thread 6, the upper axis angle becomes 330 degrees (S33: YES). At this time, the needle 10 is positioned above the cloth 99 (see fig. 12). The CPU91 controls the driving of the thread tension motor 16 to retract the upper thread 6 (S39). The upper thread 6 is moved in the retracting direction (arrow a2 in fig. 12). In the set retraction mode, the amount of movement by which the upper thread 6 is moved by the driving of the thread tension motor 16 is the amount obtained by dividing the upper thread retraction amount acquired in S3 by the number of times of upper thread retraction acquired in S11. In the present embodiment, the CPU91 moves the upper thread 6 in the retracting direction by substantially half the retracting amount of the upper thread acquired in S3, and rewrites the accumulated moving amount of the upper thread 6 in the retracting direction in the RAM 93. When the operator does not step back on the pedal 38 (S43: no), the CPU91 shifts the process to S30.

After the upper shaft angle exceeds 330 degrees (S33: NO), the CPU91 executes a normal process (S35). As the thread take-up lever 51 lifts the upper thread 6, the upper thread 6 is stretched and the tension of the upper thread 6 rises. When the tension of the face line 6 exceeds the set tension acquired in S17, the phase difference exceeds the target value (S63: yes). The CPU91 determines the energization types corresponding to the respective plurality of coils 33 (S65). The CPU91 determines the energization type capable of eliminating the difference between the phase difference acquired in S63 and the target value based on the first relational expression, the second relational expression, and the pinching rotation angle acquired in S61. The CPU91 energizes the plurality of coils 33 in accordance with the energization type determined in S65 (S67). After the output shaft 18 rotates, the phase difference becomes coincident with the target value, and the tension of the face line 6 is restored to the set tension acquired in S17. The CPU91 acquires the rotated pinch rotation angle of the output shaft 18 based on the encoder 21, and rewrites the acquired pinch rotation angle in the RAM93 with the acquired pinch rotation angle as a reference phase. The CPU91 ends the normal processing.

As shown in fig. 8, when the CPU91 repeatedly executes S30 to S43, the sewing machine 1 forms a stitch 98 and finishes sewing one stitch. The upper axis angle reached 690 degrees (S33: YES). The CPU91 performs the withdrawal of the upper thread 6 for the second time (S39). The sum of the retracting amounts of the upper thread 6 twice coincides with the retracting amount of the upper thread acquired in S3. When the operator does not step back on the pedal 38 (S43: no), the CPU91 shifts the process to S30. The accumulated moving amount of the upper thread 6 stored in the RAM93 reaches the upper thread retracting amount acquired in S3 within the number of sewing starting needles acquired in S5 (S30: YES). At this time, the CPU91 executes normal processing in the same manner as described above (S35). The CPU91 repeatedly executes S30, S35, and S43, and the sewing mechanism 12 sequentially forms stitches 98 on the fabric 99. When the operator steps back on the pedal 38 (yes in S43), the CPU91 drives the thread cutting solenoid 161 to perform a thread cutting operation of cutting the upper thread 6 and the lower thread 9 (S45), stops the driving of the driving motor (S47), controls the driving of the cloth pressing motor 43 to raise the presser foot 24 (S49), and then ends the sewing process. The sewn fabric 99 can be taken off from the sewing machine 1.

The sewing process in the case where the operator inputs the automatic retraction mode will be described. Hereinafter, a description overlapping with the above sewing process will be omitted. The operator inputs one needle as the number of sewing needles (S5), and inputs the automatic retraction mode (S7, S9: YES). The CPU9 acquires the upper shaft angle and the thread tension rotation angle (S15), and acquires the set tension of the upper thread 6 (S17), and acquires a target value corresponding to the set tension (S19). When the operator steps on the pedal 38 (yes in S21), the CPU91 controls the driving of the presser motor 43 to lower the presser foot 24 (S23), starts the energization of the plurality of coils 33 (S25), drives the thread take-up motor 16, and moves the upper thread 6 in the feeding direction (S27). The CPU91 starts driving of the drive motor (S29). Since the moving amount of the upper thread 6 in the retracting direction is 0 (S30: NO), the CPU91 shifts the process to S31, and determines that the upper thread retracting mode acquired in S7 is the automatic retracting mode (S31: YES). The CPU91 determines whether the take-up lever lifting period has come based on the encoder 27A (S37). When the thread take-up lever is not lifted up immediately after the start of sewing (S37: NO), the CPU91 transfers the process to S35. The CPU91 repeatedly executes S35, S43, S30, S31, S37. When the thread take-up lever lifting period in the first needle is started (S37: YES), the CPU91 retracts the upper thread 6 (S39). In the automatic retraction mode, the movement amount by which the upper thread 6 is moved by the driving of the thread tension motor 16 is an amount obtained by dividing the retraction amount of the upper thread acquired in S3 by the number of stitches acquired in S5. Therefore, the CPU91 can complete the retraction of the upper thread 6 within the number of set-up stitches acquired in S5. In the present embodiment, the CPU91 moves the upper thread 6 in the retracting direction by the upper thread retracting amount acquired in S3 by performing the process of S39 once (S39). The operator continues to step in the pedal 38 (S43: no). When the CPU91 determines that the retraction of the opposite line 6 has been completed (S30: yes), the CPU91 performs normal processing (S35). Until the operator steps back the pedal 38 (S43: no), the CPU91 continues to execute the above-described processing. When the operator steps back on the pedal 38 (yes in S43), the CPU91 drives the thread cutting solenoid 161 to cut the thread (S45), stops the driving of the driving motor (S47), controls the driving of the cloth pressing motor 43 to raise the presser foot 24 (S49), and then ends the sewing process.

As described above, the CPU91 controls the drive of the thread tension motor 16 to move the upper thread 6 in the retracting direction by a predetermined amount based on the amount of penetration of the upper thread 6 into the needle eye 10A (S39). The amount of the face thread 6 left on the cloth 99 at the time of sewing is small. Therefore, the sewing machine 1 can suppress the occurrence of the upper thread 6 being tangled and lumped under the cloth 99 at the time of starting sewing.

The CPU91 controls the drive of the thread tension motor 16 a plurality of times at the time of starting the sewing so that the upper thread 6 is moved by the upper thread take-up amount acquired in S3 in a total of a plurality of movements (S39). By moving the upper thread 6 by the CPU91 a plurality of times, the upper thread 6 is less likely to be separated from the eye 10A of the needle 10, i.e., separated from the needle eye, than when the upper thread 6 is moved only once. Therefore, the sewing machine 1 can suppress the thread slipping at the time of starting sewing.

When the upper axis angle is 330 degrees, for example (S33: YES), the CPU91 moves the upper thread 6 in the retracting direction (S39). The upper axis angle of 330 degrees corresponds to a timing after the needle 10 penetrates the cloth 99 for the first time and before the needle penetrates the cloth for the second time. The thread separation is easily caused by the friction between the upper thread 6 held in the eye 10A of the needle 10 moving up and down and the cloth 99. Since the timing at which the upper thread 6 moves in the retracting direction is after the needle 10 first penetrates the fabric 99, the sewing machine 1 can suppress the thread slipping-off from occurring when the needle 10 first penetrates the fabric 99.

When the operator inputs the automatic retraction mode (S7), the CPU91 rotates the thread take-up reel 69 while the thread take-up lever 51 is lifting up the upper thread 6 (S37: yes) (S39). The upper thread 6 is more easily stretched during the raising of the thread take-up lever, and therefore, the upper thread 6 is more easily moved in the retracting direction. The sewing machine 1 can further suppress the occurrence of the upper thread 6 being tangled and lumped under the cloth 99 at the time of starting sewing.

The CPU91 moves the upper thread 6 by a predetermined amount within the number of set stitches acquired in S5 (S39). The sewing machine 1 can limit the sewing start period according to the number of stitches input by the input unit 47. Therefore, the sewing machine 1 can diversify the manner of moving the upper thread 6 by controlling the driving of the thread tension motor 16.

The CPU91 moves the upper thread 6 in the retracting direction at the upper thread retracting timing acquired in S13 (S39). The timing of moving the upper thread 6 by controlling the driving of the thread take-up motor 16 is changed in accordance with the timing inputted by the input unit 47. Therefore, the sewing machine 1 can diversify the manner of moving the upper thread 6 by controlling the driving of the thread tension motor 16.

The CPU91 moves the upper thread 6 in the retracting direction by the upper thread retracting amount inputted by the input section 47 (S39). The amount of movement of the upper thread 6 by controlling the driving of the thread tension motor 16 is changed according to the amount of retraction of the upper thread inputted by the input unit 47. Therefore, the sewing machine 1 can diversify the manner of moving the upper thread 6 by controlling the driving of the thread tension motor 16.

The timing (S27) of the movement of the upper thread 6 in the feeding direction is before the start of the driving motor (S29). That is, the CPU91 moves the upper thread 6 in the feeding direction before the upper thread 6 is moved in the retracting direction by the thread tension motor 16 and before the needle 10 penetrates the fabric 99 for the first time. The upper thread 6 is moved in the feeding direction before the upper thread 6 is moved in the retracting direction by the thread tension motor 16. Therefore, the sewing machine 1 can prevent the upper thread 6 threaded through the eye 10A from being insufficient when the needle 10 first penetrates the fabric 99, and can reliably suppress thread slipping.

In the above description, the sewing mechanism 12 is an example of the sewing portion of the present invention. The clamp motor 16 is an example of the driving unit of the present invention. The input unit 47 is an example of the needle number input unit, the timing input unit, and the movement amount input unit according to the present invention. The CPU91 when S39 is executed is an example of the needle thread take-up section of the present invention. The CPU91 executing S37 exemplifies the determination unit of the present invention. The CPU91 when executing S27 is an example of the upper thread supplying section of the present invention.

The present invention is not limited to the above-described embodiments. The sewing machine 1 may also be a flat-stitch sewing machine, a keyhole sewing machine, a home sewing machine, an embroidery sewing machine, or the like. The sewing machine 1 may be a circular sewing machine or the like without the shuttle mechanism 40. After the thread cutting is completed (S45), the CPU91 may drive the driving motor to continue the sewing operation while forming the stitch 98 on the fabric 99. In this case, the sewing that is started after the cutting is performed is the set seam.

The CPU91 may acquire the needle thread retraction amount not based on the detection result of the input section 47 but by reading the needle thread retraction amount stored in advance in the storage device 94 (S3). The timing of the needle thread retraction inputted by the input unit 47 may be after the needle 10 penetrates the cloth 99 for the second time. In this case, the CPU91 may move the upper thread 6 in the retracting direction a plurality of times in succession when forming the second stitch 98 (S39).

The upper thread take-up timing inputted by the input unit 47 may be a timing other than the thread take-up lever raising period. In this case, the sewing machine 1 can also suppress thread separation that may occur with the lifting of the thread take-up lever 51. The number of sewing needles input by the input unit 47 may be one needle, or three or more needles. When the operator inputs the automatic retraction mode (yes in S9), the CPU91 may retract the upper thread 6 when it is determined in S37 that the thread take-up lever is not being lifted (S39).

It is also acceptable that the CPU91 does not retract the upper thread 6 in S39 in the setting of the retracting mode by the amount obtained by dividing the upper thread retracting amount acquired in S3 by the number of times of retracting the upper thread acquired in S11. When the number of times of withdrawing the upper thread acquired in S11 is two or more, the sewing machine 1 may be configured to individually set the upper thread withdrawing amounts. Alternatively, the CPU91 may not retract the upper thread 6 in S39 in the automatic retraction mode by dividing the upper thread retraction amount acquired in S3 by the number of sewing needles acquired in S5. If the number of sewing starting stitches acquired in S5 is two or more, the sewing machine 1 may be configured to set the upper thread take-up amount individually.

Claims

1. A sewing machine (1) has:

a sewing part (12) having a needle bar (11) to which a needle (10) is attached, the needle bar being capable of moving up and down, the sewing part being capable of sewing a fabric (99) with the needle moving up and down;

a wire clamping mechanism (60) having: a thread take-up reel (69) around which the upper thread (6) is wound; and a drive unit (16) for rotating the thread clamping disk, wherein the thread clamping mechanism adjusts the supply amount of the surface thread to the needle by the rotation of the thread clamping disk;

a sewing control part (91) for sewing the cloth by controlling the sewing part; and

a thread adjusting control part for controlling the drive part to control the supply amount of the upper thread to the needle when the sewing control part controls the sewing of the cloth,

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

the thread adjusting control unit has a thread take-up control unit that controls the drive unit to move the upper thread in a take-up direction, which is a reverse direction of a feeding direction in which the upper thread is fed to the needle, by a predetermined amount based on an amount of the upper thread threaded on the needle when the sewing control unit controls the sewing of the fabric.

2. The sewing machine of claim 1,

when the sewing control part controls the sewing of the cloth, the thread withdrawing control part controls the driving part for a plurality of times to make the upper thread move for the specified amount under the movement of the plurality of times.

3. Sewing machine as in claim 1 or 2,

the thread take-up control section moves the upper thread in the take-up direction at least once after the needle pierces the fabric for the first time from the start of sewing by the sewing control section and before the needle pierces the fabric for the second time.

4. Sewing machine as in claim 1 or 2,

the sewing part is provided with a thread take-up lever (51) which lifts the upper thread by moving up and down synchronously with the up and down movement of the needle bar,

the thread adjusting control part has a judging part for judging whether the take-up lever is lifting the upper thread,

the thread take-up control section moves the upper thread when the judgment section judges that the thread take-up lever is lifting up the upper thread.

5. Sewing machine as in claim 1 or 2,

the sewing machine has a needle number input part (47) for inputting the number of needles for limiting the sewing by the control of the sewing control part,

the thread take-up control section moves the upper thread by the predetermined amount within the needle count input by the needle count input section.

6. Sewing machine as in claim 1 or 2,

the sewing machine has a timing input part for inputting the timing of the upper thread moving by the thread take-up control part,

the thread retracting control section moves the upper thread in the retracting direction at the timing input by the timing input section.

7. Sewing machine as in claim 1 or 2,

the sewing machine has a movement amount input part, which can input the specified amount,

the thread retraction control unit moves the upper thread by the predetermined amount input by the movement amount input unit.

8. Sewing machine as in claim 1 or 2,

the thread adjusting control part has a thread supplying control part which makes the upper thread move to the supplying direction before the thread withdrawing control part makes the upper thread move and before the needle penetrates the cloth for the first time,

the thread take-up control section moves the upper thread by the predetermined amount after the needle pierces the fabric for the first time.