JP2019166039A - sewing machine - Google Patents

Abstract

To provide a sewing machine capable of setting a tensile force of a needle thread at a necessary tensile force compared with the conventional one.SOLUTION: A sewing machine includes: a sewing part having a needle bar on which a needle is mounted and which can move vertically, and a balance which moves vertically synchronized with the vertical movement of the needle bar and raises the needle thread, and for forming seams on a cloth by the needle; a thread tension mechanism for imparting a tensile force to the needle thread; a drive part for driving the thread tension mechanism; and a control part for performing drive control of the sewing part and the drive part. The control part forms seams on a cloth by performing drive control of the sewing part (S10). During the drive control of the sewing part in S10 and since the time when the needle bar is located at a lower dead point in the vertical movement range until the time when the balance is located at an upper dead point in the vertical movement range, the control part performs drive control of the drive part and controls the supply of the needle thread (S11: YES or S13: YES), and moves the needle thread in a recovery direction opposite from the supply direction (S12, S14).SELECTED DRAWING: Figure 8

Description

  The present invention relates to a sewing machine.

  A sewing machine that controls the tension of the upper thread during sewing with a pulse motor is known. For example, the sewing machine disclosed in Patent Document 1 includes a thread tension plate, a pulse motor, an encoder, an operation panel, and a sewing machine motor. The pulse motor has an output shaft. The sewing machine controls driving of the pulse motor by inputting a driving pulse to the pulse motor driving unit. The thread tension plate is fixed to the output shaft. Upper thread is wound around the thread tension plate. The encoder detects the rotational position of the output shaft. The operator inputs the upper thread tension to the sewing machine via the operation panel. When the sewing machine motor is driven, the sewing machine moves the needle bar up and down and executes a sewing operation. When the sewing machine motor is driven, the sewing machine drives and controls the pulse motor based on the detection result of the encoder so that the tension of the upper thread becomes the inputted tension.

JP 2009-89823 A

  Depending on the material of the cloth to be sewn, the operator may want to change the tension of the upper thread at a predetermined timing in the cycle in which the needle bar moves up and down. The sewing machine drives and controls the pulse motor so that the tension of the upper thread is maintained when the sewing machine motor is driven. Therefore, there are times when the upper thread tension does not become the required tension in the above-mentioned sewing machine, and the stitches are not stable and sewing failure may occur.

  An object of the present invention is to provide a sewing machine capable of setting the upper thread tension to a necessary tension as compared with the prior art.

  A sewing machine according to an aspect of the present invention has a needle bar that can be moved up and down to attach a sewing needle, and a balance that moves up and down in synchronization with the vertical movement of the needle bar to pull up an upper thread. In a sewing machine comprising: a sewing part that forms an eye; a thread tension mechanism that applies tension to the upper thread; a drive part that drives the thread tension mechanism; and a control part that drives and controls the sewing part and the drive part. The control unit includes a sewing control unit that drives and controls the sewing unit to form the stitches on the cloth, and the needle bar is in a vertical movement range during the drive control of the sewing unit by the sewing control unit. From the time when the balance is positioned at the bottom dead center to the time when the balance is positioned at the top dead center of the vertical movement range, the drive unit is driven to control the supply of the upper thread, and the upper thread is supplied in the supply direction. It functions as a thread tension control unit that moves in the recovery direction opposite to the above.

  The sewing machine of this aspect controls the supply of the upper thread by controlling the driving unit during sewing, and can move the upper thread supplied to the balance side from the thread tension mechanism in the direction opposite to the supply direction. By moving the upper thread, the sewing machine can apply an appropriate tension to the upper thread when the balance is pulled up, and can reliably apply the necessary tension to the upper thread as compared with a conventional sewing machine. Therefore, in the sewing machine, the stitches are stabilized when sewing as compared with the conventional sewing machine, and poor sewing can be suppressed.

  The sewing machine of this aspect includes a thread tension plate around which the upper thread is wound, a motor that is the drive unit having an output shaft that rotatably supports the thread tension plate, and an encoder that detects a rotation angle of the output shaft. The thread tension control unit rotates and controls the motor in a direction opposite to the rotation direction for supplying the upper thread during the drive control of the sewing unit by the sewing control unit. Good. The sewing machine can drive and control the motor to rotate the thread tension plate in the direction opposite to the direction in which the upper thread is supplied, thereby moving the upper thread supplied to the balance side from the thread tension plate in the collecting direction.

  The sewing machine of this aspect includes a hook having a sword tip that captures the loop of the upper thread inserted through the sewing needle, a hook mechanism that rotates the hook in conjunction with the vertical movement of the sewing needle, and the thread tension control unit When the hook is rotated by the hook mechanism, the drive unit is moved during a hook removal period from when the loop of the upper thread captured by the sword tip comes out of the hook until the tension is applied to the upper thread by lifting the balance. Drive control may be performed. The sewing machine can move the upper thread in the collecting direction by driving and controlling the motor during the hook removal period. The sewing machine moves the upper thread supplied excessively between the thread tension plate and the seam in the collecting direction, so that an appropriate tension can be applied to the upper thread when lifting the balance, which is due to insufficient tension of the upper thread during sewing. Sewing defects can be suppressed.

  The sewing machine according to this aspect further includes a first input unit that inputs a first rotation amount that the thread tension control unit drives and controls the motor to rotate in the opposite direction during the hook removal period, and the control unit includes: It further functions as a first acquisition unit that acquires the first rotation amount input by the first input unit, and the thread tension control unit drives and controls the motor during the hook pull-out period to control the thread tension plate. The first rotation amount may be rotated in the opposite direction. In conventional sewing machines, when adjusting the tension of the upper thread, the thread take-up spring is adjusted according to the operator's intuition. When adjusting the tension of the upper thread, the sewing machine of this aspect can quantify the variable (first rotation amount) for adjusting the tension of the upper thread. Therefore, the sewing machine can improve the reproducibility of adjusting the upper thread tension during the hook removal period compared with the conventional sewing machine. The operator can easily adjust the needle thread tension during the hook removal period compared to the conventional case.

  The thread tension control unit of the sewing machine according to the aspect of the present invention is configured so that when the hook is rotated by the hook mechanism, the loop of the upper thread captured by the sword from the encounter where the knives catch the upper thread is removed from the hook. During the hook catching period, the motor may be driven to rotate the thread tension plate in the opposite direction. The sewing machine can apply the necessary tension to the upper thread during the hook catching period.

  The sewing machine according to this aspect further includes a detection unit that outputs an output value corresponding to an upper thread supply amount that is a supply amount of the upper thread in the supply direction to the control unit, and the control unit includes the yarn tension control unit. In the hook catching period, the upper thread supply during the period until the loop of the upper thread caught by the sword is pulled out of the hook after the motor is driven and controlled to rotate the thread tension plate in the opposite direction. You may further function as an output value acquisition part which acquires the output value according to quantity, and a judgment part which judges whether skipping occurred according to the output value which the output value acquisition part acquired. The sewing machine can accurately determine the presence or absence of stitch skipping in the period until the upper thread loop captured by the sword is pulled out of the hook.

  The sewing machine according to this aspect further includes a second input unit that inputs a second rotation amount by which the thread tension control unit drives and controls the motor to rotate the thread tension plate in the opposite direction during the hook capturing period. The control unit further functions as a second acquisition unit that acquires the second rotation amount input by the second input unit, and the thread tension control unit drives and controls the motor during the hook capturing period, The thread tension plate may be rotated in the opposite direction by the second rotation amount. In conventional sewing machines, when adjusting the tension of the upper thread, the thread take-up spring is adjusted according to the operator's intuition. When adjusting the tension of the upper thread, the sewing machine of this aspect can quantify the variable (second rotation amount) for adjusting the tension of the upper thread. Therefore, the sewing machine can improve the reproducibility of adjusting the upper thread tension during the hook catching period as compared with the conventional sewing machine. The operator can easily adjust the needle thread tension during the hook catching period compared to the conventional case.

The perspective view of the sewing machine 1. FIG. Sectional drawing of the thread tension mechanism 60. FIG. The conceptual diagram of the output shaft 18 and the coil 33 of the thread tension motor 16. FIG. FIG. 2 is an electric block diagram of the sewing machine 1. The graph which shows a 1st relational expression and a 2nd relational expression. Explanatory drawing which shows the flow in which the rotary hook 39 catches the upper thread 6. FIG. 4 is an explanatory diagram showing a needle bar movement curve of the needle bar 11, a balance thread amount curve of the balance 51, a hook thread amount curve of the rotary hook 39, and a supply amount of the upper thread 6. The flowchart of a sewing process. Flow chart of normal processing.

  Embodiments of the present invention will be described below. In the following description, left, right, front, back, and top and bottom indicated by arrows in the figure are used. The sewing machine 1 shown in FIG. 1 is a tacking sewing machine that forms tacking stitches on the cloth 99.

  The schematic structure of the sewing machine 1 will be described with reference to FIGS. The sewing machine 1 includes a bed 2, a pedestal 3, and an arm 4. The bed 2 is a base of the sewing machine 1 and is installed on a work table extending horizontally. The bed portion 2 includes a bed main body portion 7 and a cylinder bed portion 8. The bed main body 7 is substantially box-shaped. The cylinder bed portion 8 extends forward from the bed main body portion 7. The inside of the bed main body portion 7 and the inside of the cylinder bed portion 8 communicate with each other. The cylinder bed portion 8 includes a needle plate 26 on the upper surface of the front end portion. The operator places the cloth 99 on the needle plate 26. The needle plate 26 has a needle hole. The pedestal part 3 extends upward from the rear part of the bed main body part 7. The arm part 4 extends forward from the upper part of the columnar part 3 and faces the bed part 2. A front end portion of the arm portion 4 is a tip portion 5. The tip 5 includes a right wall 5A and a through hole 5B (see FIG. 2). The right wall portion 5 </ b> A is a wall portion on the right side of the tip portion 5. The through hole 5B penetrates the right wall portion 5A in the left-right direction.

  As shown in FIG. 4, the sewing machine 1 includes a control device 30, an operation unit 46, and a pedal 38. The control device 30 is fixed to the lower surface of the work table. The control device 30 controls the operation of the sewing machine 1. The operation unit 46 is fixed to the upper surface of the work table. The operation unit 46 includes a display unit 48 and operation buttons 47. The display unit 48 displays various information. The operation button 47 detects various information input by the operator. The operation button 47 includes a power button.

  As shown in FIG. 1, the sewing machine 1 includes a sewing mechanism 12. As shown in FIGS. 1 and 6, the sewing mechanism 12 has a needle bar 11 that can be moved up and down with a sewing needle 10, and the sewing needle 10 forms a seam 98 on the cloth 99. The sewing mechanism 12 includes a main motor 27 (see FIG. 4), an upper shaft 15, a linkage, a balance mechanism, a needle bar vertical movement mechanism, a shuttle mechanism 40, and a cloth feeding device 20. The main motor 27 is supported at the rear part of the arm part 4. The upper shaft 15 extends in the front-rear direction inside the arm portion 4. The rear end portion of the upper shaft 15 is connected to the output shaft of the main motor 27 through a joint. The upper shaft 15 is rotated by driving the main motor 27. The front end portion and the rear end portion of the upper shaft 15 are coaxial with each other. The upper shaft 15 includes a crank portion in the vicinity of the rear end portion. The crank portion is a curved portion that is curved at a position deviated from the axis of the front end portion and the rear end portion of the upper shaft 15. The linkage extends in the vertical direction inside the pedestal 3. The upper end portion of the linkage is connected to the crank portion so as to be rotatable.

  The balance mechanism and the needle bar up-and-down moving mechanism are supported by the tip 5. The balance mechanism includes a balance crank and a balance 51. The balance crank is connected to the front end portion of the upper shaft 15. The balance 51 is provided on the balance crank. As the balance crank rotates together with the upper shaft 15, the balance 51 moves up and down in conjunction with the up and down movement of the needle bar 11. The balance 51 has an upper thread insertion hole. The balance 51 holds the upper thread 6 inserted into the upper thread insertion hole. The upper thread 6 (see FIG. 6) is fed from a thread supply source, and reaches the upper thread insertion hole of the balance 51 via a thread tension mechanism 60 described later.

  The needle bar vertical movement mechanism includes a needle bar crank rod, a needle bar 11 and the like. The needle bar crank rod is pivotally connected to the balance crank and extends in the vertical direction. The needle bar 11 extends in the vertical direction and is connected to the needle bar crank rod. A sewing needle 10 is attached to the lower end of the needle bar 11. The sewing needle 10 has a hole at the lower end. The sewing needle 10 inserts and holds the upper thread 6 through the upper thread insertion hole of the balance 51 through the eye hole. The needle bar 11 moves up and down together with the sewing needle 10 as the needle bar crank rod reciprocates as the balance crank rotates.

  The shuttle mechanism 40 is provided inside the bed portion 2. The shuttle mechanism 40 includes a rotation shaft, an arm portion, a lower shaft, and a rotary shuttle 39. The rotation shaft is rotatably supported by the bed main body 7 and extends in the front-rear direction inside the bed main body 7. The arm portion is fixed to the rotation shaft and protrudes rightward from the rotation shaft. The tip of the arm is pivotably connected to the lower end of the linkage. As the linkage reciprocates as the upper shaft 15 rotates, the arm reciprocates around the rotation shaft. The lower shaft extends in the front-rear direction inside the bed main body portion 7 and the cylinder bed portion 8 and can rotate. The lower shaft is below the upper shaft 15 and to the left of the rotation shaft. The lower shaft is connected to the rotating shaft through a connecting portion. The lower shaft reciprocates in conjunction with the rotation shaft.

As shown in FIG. 6, the rotary hook 39 is provided at the front end of the lower shaft and is below the needle hole. The rotary hook 39 can rotate around the lower shaft. The rotary hook 39 includes a sword tip 36 (see FIG. 6). The sword tip 36 is a part of the outer peripheral portion of the rotary hook 39 and protrudes toward the front view clockwise with the lower shaft as the center.
The rotary hook 39 can be fitted with a bobbin case 32. The bobbin case 32 accommodates the bobbin around which the lower thread 9 is wound. The bobbin case 32 includes a drawer portion 34. The drawing portion 34 pulls the lower thread 9 drawn out from the bobbin to the outside.

  As shown in FIGS. 1 and 4, the cloth feed device 20 includes a movable body 31, a swing shaft, a feed base 37, a swing motor 41, a feed plate, a rack shaft 22, a moving motor 42, a presser arm 23, and a presser foot motor 43. Is provided. The movable body 31 is provided so as to be movable back and forth within the bed main body 7. The swing shaft is a shaft that is fixed to the movable body 31 and extends in the vertical direction, and protrudes upward from the bed main body portion 7. The feed base 37 is connected to the movable body 31 inside the bed main body 7 and is provided on the swing shaft so as to be swingable. Therefore, the feed base 37 can move back and forth with the movable body 31 and can swing in the left-right direction around the swing axis. The swing motor 41 is connected to the feed base 37. When the swing motor 41 is driven, the feed base 37 swings around the swing shaft. The feed plate is disposed on the upper surface of the bed portion 2. The feed plate supports the cloth 99. The feed plate moves back and forth integrally with the feed base 37 and swings. The feed plate has a hole at the front end. The sewing needle 10 that moves up and down passes through the hole in the feed plate and reaches the needle hole in the needle plate 26.

  The rack shaft 22 extends in the front-rear direction above the bed main body 7 and can move back and forth. The front end portion of the rack shaft 22 is connected to the upper end portion of the swing shaft. The rear end portion of the rack shaft 22 is disposed inside the pedestal 3. The moving motor 42 is provided inside the pillar 3. The moving motor 42 moves back and forth on the rack shaft 22. At this time, the feed base 37, the feed plate, the swing shaft, and the movable body 31 move back and forth integrally with the rack shaft 22.

  The presser arm 23 extends upward from the feed base 37 and extends forward above the bed portion 2. The presser arm 23 can move back and forth and swing together with the feed base 37. The presser arm 23 includes a presser foot 24, a shaft portion 29, and a lever portion 25. The presser foot 24 is provided at the front end of the presser arm 23 so as to be movable up and down. The presser foot 24 is disposed above the needle plate 26. The shaft portion 29 is provided at a substantially central portion in the front-rear direction of the presser arm 23 with the left-right direction being the axial direction. The lever portion 25 is provided on each of the left surface and the right surface of the presser arm 23 and can rotate around the shaft portion 29. The front end portion of the lever portion 25 is connected to the presser foot 24. The presser foot motor 43 is provided inside the pedestal 3. The presser foot motor 43 is connected to the rear end portion of the lever portion 25 via a link mechanism provided inside the arm portion 4. The presser foot 24 moves up and down as the lever portion 25 rotates about the shaft portion 29 as the cloth presser motor 43 is driven. The presser foot 24 can press the cloth 99 with the feed plate.

  As shown in FIGS. 1 and 2, the sewing machine 1 includes a thread tension mechanism 60 on the right wall portion 5 </ b> A of the distal end portion 5. The thread tension mechanism 60 includes a thread tension case 62, a thread tension base 63, a thread take-up spring 65, a thread tension motor 16, a thread tension tray 69, and an encoder 21 (see FIG. 4). The thread tension mechanism 60 supplies the thread between the thread tension tray 69 and the seam 98 with the power of the thread tension motor 16. The thread tension case 62 is an annular member fixed with a fastening member inside the through hole 5B of the right wall portion 5A. The thread tension base 63 is an annular member fixed to the inside of the thread tension case 62 with the screw 14. The thread take-up spring 65 is fixed to the outer surface of the thread tension base 63 and is wound between the thread tension base 63 and the thread tension case 62. One end of the thread take-up spring 65 is exposed to the right from the right wall 5A. The thread tension motor 16 is fixed to the inside of the arm portion 4 with a bolt 17. An output shaft 18 (described later) of the thread tension motor 16 protrudes to the right of the right wall portion 5A through the center hole of the thread tension base 63. The thread tension plate 69 is fixed to the right end portion of the output shaft 18 with a screw 28. The upper thread 6 is wound around the thread tension plate 69 about once or twice.

  The thread tension motor 16 has an output shaft 18 that rotatably supports the thread tension tray 69, and applies tension to the upper thread 6 by rotating the thread tension tray 69 via the output shaft 18. The thread tension motor 16 is a two-phase bipolar pulse motor. The thread tension motor 16 includes an output shaft 18 and a plurality of coils 33 (see FIG. 3). The output shaft 18 can rotate with the left-right direction as the axial direction. The right end portion of the output shaft 18 supports the thread tension plate 69 on the right side of the arm portion 4. In the present embodiment, the output shaft 18 is directly connected to the thread tension tray 69. A plurality of coils 33 are arranged along the rotation direction of the output shaft 18. The number of the coils 33 of this embodiment is four. The sewing machine 1 can supply current to each coil 33 in both directions. The sewing machine 1 controls the phase difference of the output shaft 18 by electromagnetic force generated by the energized coils 33. The encoder 21 detects the rotation angle (rotation position) of the output shaft 18. The left end portion of the output shaft 18 fixes the disk of the encoder 21 inside the arm portion 4.

  The electrical configuration of the sewing machine 1 will be described with reference to FIG. The control device 30 of the sewing machine 1 includes a CPU 91. The CPU 91 controls the operation of the sewing machine 1 including the sewing mechanism 12 and the thread tension motor 16. The CPU 91 is connected to the ROM 92, RAM 93, storage device 94, and I / O interface (hereinafter referred to as I / O) 45. The ROM 92 stores programs for executing various processes such as a sewing process (see FIG. 8) described later. The RAM 93 temporarily stores various values. The storage device 94 is nonvolatile. The storage device 94 stores sewing data for forming the seam 98 on the cloth 99. The storage device 94 stores first and second relational expressions described later.

  The sewing period is a period during which sewing is performed for one stitch of the sewing machine 1, that is, a period for one rotation of the upper shaft 15. As shown in FIG. 7, the needle bar movement curve of the needle bar 11, the hook yarn amount curve of the rotary hook 39, and the balance yarn amount curve of the balance 51, the top dead center where the balance 51 is the upper end of the movable range in the sewing machine 1 of this embodiment. The period from the bottom dead center at the lower end of the movable range to the return to the top dead center is the sewing period for one stitch of the sewing machine 1. That is, in the sewing period of the present embodiment, 60 to 420 degrees of the rotation angle of the upper shaft 15 substantially matches the sewing period of one stitch. The hook removal period T1 is a period from when the upper thread 6 comes out of the rotary hook 39 until the tension is applied to the upper thread 6 by lifting the balance 51. The hook catching period T <b> 2 is a period during which the rotary hook 39 catches the upper thread 6 with the sword tip 36. The hook catching period T2 is a period from “hook on the hook” where the sword tip 36 meets the sewing needle 10 and hooks the upper thread 6 to “missing upper thread from the hook” where the upper thread 6 comes off from the rotary hook 39. The detection period H is a period for monitoring the occurrence of skipping. The detection period H is provided immediately before the upper thread loop is released. The detection period H in this example is a period from “hook on the hook” to the top dead center of the needle bar, and includes the balance dead center and the top dead center of the needle bar. The CPU 91 sets the hook removal timing (first time) provided during the hook removal period T1, the hook capture timing (second time) provided during the hook capture period T2, and the detection period H as the rotation angle of the upper shaft 15 based on the detection result of the encoder 27A. Judgment by. The hook catching timing in this example is provided within a period T3 on the “hook upper hook” side of the detection period H.

  The first and second relational expressions use the thread tension motor 16 during drive control. The first relational expression is an expression that relates the A-phase current flowing in the A-phase that is one phase of the thread tension motor 16 and the electrical angle. The second relational expression is an expression that relates the B-phase current flowing in the B-phase that is the other phase and the electrical angle. As shown in FIG. 5, the graph representing the A-phase current and the B-phase current shows two sine curves whose phases are shifted from each other by 90 degrees. The electrical angle of 360 degrees in this embodiment corresponds to a mechanical angle of 7.2 degrees. The CPU 91 drives and controls the thread tension motor 16 so that the phase difference of the output shaft 18 becomes a target value.

  The I / O 45 is connected to the drive circuits 81-86. The drive circuit 81 is connected to the main motor 27. The main motor 27 is a DC brushless motor. The drive circuit 82 is connected to the swing motor 41. The drive circuit 83 is connected to the movement motor 42. The drive circuit 84 is connected to the presser foot motor 43. The swing motor 41, the movement motor 42, and the cloth presser motor 43 are pulse motors. The output shafts of the main motor 27, the swing motor 41, the moving motor 42, and the presser foot motor 43 are provided with encoders 27A, 41A, 42A, and 43A, respectively. The encoders 27A, 41A, 42A, and 43A detect the rotational positions of the output shafts of the main motor 27, the swing motor 41, the moving motor 42, and the presser foot motor 43, respectively, and output them to the CPU 91 via the I / O 45. CPU91 acquires the detection result of encoder 27A, 41A, 42A, 43A, and transmits a control signal to the drive circuits 81-84. Therefore, the CPU 91 drives and controls the main motor 27, the swing motor 41, the moving motor 42, and the presser foot motor 43. Hereinafter, the main motor 27, the swing motor 41, and the moving motor 42 are collectively referred to as a drive motor.

  The drive circuit 85 is connected to the thread tension motor 16. The encoder 21 outputs the rotational position of the output shaft 18 of the thread tension motor 16 to the CPU 91 as a detection result. The CPU 91 controls the thread tension motor 16 by transmitting a control signal to the drive circuit 86. A control method executed by the CPU 91 for the thread tension motor 16 will be described later.

  The drive circuit 86 is connected to the display unit 48 of the operation unit 46. The CPU 91 displays various information on the display unit 48 by transmitting a control signal to the drive circuit 86. The operation button 47 of the operation unit 46 outputs the detected various information to the CPU 91 via the I / O 45. The pedal 38 outputs the detection result to the CPU 91 via the I / O 45. The CPU 91 acquires the operation direction and the operation amount of the pedal 38 indicated by the detection result of the pedal 38.

  The operation outline of the sewing machine 1 will be described with reference to FIG. The cloth 99 is placed on the feed plate and the needle plate 26. When the cloth presser motor 43 is driven, the presser foot 24 descends and presses the cloth 99 with the feed plate. The main motor 27, the moving motor 42, and the swing motor 41 are driven in synchronization with each other. The presser arm 23 and the feed plate move back and forth as the moving motor 42 is driven, and swing back and forth in the left-right direction as the swing motor 41 is driven. Therefore, the cloth feeding device 20 moves the cloth 99 back and forth and swings back and forth in the left-right direction. When the main motor 27 is driven synchronously with the moving motor 42 and the swing motor 41, the upper shaft 15 rotates. The needle bar vertical movement mechanism, the balance mechanism, and the rotary hook 39 are driven in conjunction with each other. The sewing needle 10 descending together with the needle bar 11 passes through the cloth 99 and passes through the needle hole. The upper thread 6 in the vicinity of the eye hole lowered to the lower side of the needle hole becomes a loop shape (see FIG. 6A). When the rotary hook 39 rotates clockwise in front view, the sword tip 36 captures the loop-shaped upper thread 6 (see FIG. 6B). The sewing needle 10 rises toward the upper side of the cloth 99, and the rotary hook 39 further rotates clockwise as viewed from the front. The sword tip 36 pulls the loop-shaped upper thread 6 in the rotating direction, and the loop-shaped upper thread 6 expands in diameter. When the looped upper thread 6 passes through the rotary hook 39 (see FIG. 6C), the upper thread 6 is entangled with the lower thread 9. The rotating direction of the rotary hook 39 is switched counterclockwise when viewed from the front, and the balance 51 pulls up the upper thread 6 entangled with the lower thread 9 (see FIG. 6D). The looped upper thread 6 is reduced in diameter, and the sewing machine 1 completes the sewing of the first stitch. In the present embodiment, every time the upper shaft 15 rotates 360 degrees, the sewing machine 1 executes sewing for one stitch. The sewing machine 1 forms the seam 98 on the cloth 99 by repeating the above operation.

  The sewing process will be described with reference to FIG. The sewing process is a process in which the sewing machine 1 sews the cloth 99. For example, when the operator operates the operation button 47 to start supplying power to the sewing machine 1, the CPU 91 reads a program from the ROM 92 to the RAM 93 and executes a sewing process.

  As shown in FIG. 8, the CPU 91 executes an initialization process (S1). For example, the CPU 91 reads various setting values from the storage device 94 into the RAM 93. The CPU 91 acquires the rotation angle of the output shaft 18 of the thread tension motor 16 based on the detection result of the encoder 21 (S2). CPU91 acquires the 1st and 2nd movement amount which operation button 47 inputs (S3). The first movement amount is greater than that of the thread tension mechanism 60 by rotating the thread tension tray 69 in the direction opposite to the rotation direction in which the upper thread 6 is supplied (counterclockwise as viewed from the right side) at the hook removal timing (first timing). This is the amount by which the upper thread 6 supplied to the balance 51 is moved in the collection direction. The collection direction is closer to the yarn supply unit (for example, the thread spool) than the thread tension mechanism 60. The second moving amount is an amount by which the upper thread 6 supplied to the balance 51 side from the thread tension mechanism 60 is moved in the collection direction by rotating the thread tension plate 69 in the opposite direction at the hook catching timing (second time). It is. The first and second movement amounts may be absolute amounts representing the length of the upper thread 6 moving in the collection direction, or may be relative amounts. For example, when the operator operates the operation button 47 and inputs a specific numerical value as the first movement amount, the CPU 91 acquires the input first movement amount. When the operator operates the operation button 47 and inputs a specific numerical value as the second movement amount, the CPU 91 acquires the input second movement amount. The CPU 91 may acquire the predetermined value as the first and second movement amounts. The first and second rotation amounts may be the same or different from each other.

  The CPU 91 calculates a target value corresponding to the predetermined tension acquired in S2 (S4). The torque generated by the thread tension motor 16 and the needle thread tension are correlated with each other. The target value is the phase difference of the output shaft 18 when the needle thread tension value calculated based on the correlation stored in the storage device 94 becomes a predetermined tension. The predetermined tension may be a value input by an operator or a predetermined value. The CPU 91 calculates the first and second rotation amounts from the first and second movement amounts acquired in S3, depending on the correlation between the rewinding amount and the thread tension motor 16 (S5). The first rotation amount is the rotation amount in the opposite direction of the output shaft 18 of the thread tension motor 16 at the hook removal timing. The second rotation amount is the rotation amount in the opposite direction of the output shaft 18 of the thread tension motor 16 at the hook catching timing.

  The CPU 91 determines whether or not a sewing start instruction that is an instruction to start the sewing operation of the sewing machine 1 has been detected (S6). The sewing start instruction is an instruction that the operator inputs by operating the operation button 47 or the pedal 38. The CPU 91 stands by until a sewing start instruction is detected (S6: NO). The operator places the cloth 99 on the needle plate 26 and the feeding plate while the CPU 91 is on standby. When the operator inputs a sewing start instruction after placing the cloth 99 (S6: YES), the CPU 91 drives and controls the cloth presser motor 43 to lower the presser foot 24 (S7). The presser foot 24 sandwiches the cloth 99 with the feed plate. CPU91 specifies the electricity supply pattern with respect to each of the some coil 33 (S8). The CPU 91 specifies the energization pattern including the A-phase current and the B-phase current based on the rotation angle of the output shaft 18 acquired in S2, the target value calculated in S4, the first relational expression, and the second relational expression.

  The CPU 91 drives and controls the drive motor and drives and controls the sewing mechanism 12 to form the stitches 98 on the cloth 99 (S10). The needle bar 11, the rotary hook 39, and the feed base 37 operate in synchronization with each other. The CPU 91 determines whether it is the first time based on the output value of the encoder 27A (S11). When it is the first time (S11: YES), the CPU 91 controls the drive circuit 85, and the first rotation amount calculated in S5 for the output shaft 18 of the thread tension motor 16 according to the output value of the encoder 21 is in the opposite direction (right side surface). It rotates counterclockwise (S12). The CPU 91 drives and controls the thread tension motor 16 until the rotation amount of the output shaft 18 of the thread tension motor 16 reaches the first rotation amount in the opposite direction by the encoder 21. When it is not the first time (S11: NO), the CPU 91 determines whether it is the second time based on the output value of the encoder 27A (S13). At the second time (S13: YES), the CPU 91 controls the drive circuit 85 to rotate the output shaft 18 of the thread tension motor 16 in the direction opposite to the second rotation amount calculated in S5 according to the output value of the encoder 21. (S14). The CPU 91 drives and controls the thread tension motor 16 until the rotation amount of the output shaft 18 of the thread tension motor 16 reaches the second rotation amount in the opposite direction by the encoder 21. After S12 or S14, the CPU 91 performs S22 described later.

  When it is not the second time (S13: NO), the CPU 91 executes normal processing (S15). In the normal processing, the upper thread tension applied to the upper thread 6 by the thread tension tray 69 is controlled to be a predetermined tension. As shown in FIG. 9, the rotation angle of the output shaft 18 of the thread tension motor 16 is acquired (S31). CPU91 judges whether a comparison value is larger than a threshold (S32). The comparison value is an absolute value obtained by subtracting the target value acquired in S4 from the phase difference of the output shaft 18. The CPU 91 calculates a comparison value using the phase difference of the output shaft 18 calculated based on the rotation angle of the output shaft 18 acquired in S21 and the current energization pattern. The threshold value is a number larger than 0 determined in consideration of the target value. At the start of the sewing operation by the sewing machine 1, the comparison value is theoretically 0 (S32: NO). At this time, the CPU 91 ends the normal process as described above, and returns the process to the sewing process of FIG.

  For example, in the normal process after a predetermined number of times from the start of the sewing process (S15), it is assumed that the comparison value exceeds the threshold (S32: YES). CPU91 specifies the electricity supply pattern with respect to the some coil 33 (S33). For example, the CPU 91 identifies the energization pattern for eliminating the difference between the phase difference of the output shaft 18 acquired in S32 and the target value based on the rotation angle of the output shaft 18 acquired in S31, the first relational expression, and the second relational expression. (S33). The CPU 91 switches the energization pattern being executed for the plurality of coils 33 to the energization pattern specified in S33 (S34). The upper thread tension returns to the predetermined tension acquired in S2. The CPU 91 ends the normal process. Each time the CPU 91 executes S33, the energization pattern is specified by calculation control based on the detection result of the encoder 21 (S33), and the energization pattern for the plurality of coils 33 is switched (S34). When the CPU 91 repeatedly executes S15, the sewing machine 1 maintains the upper thread tension at a predetermined tension corresponding to the target value acquired in S4.

  The CPU 91 determines whether the detection period is H or not based on the output value of the encoder 27A (S17). When it is not the detection period H (S16: NO), the CPU 91 performs S22 described later. When it is the detection period H (S16: YES), the CPU 91 acquires the output value of the encoder 21 as an output value corresponding to the hook pull-in amount of the upper thread 6 (S17). The hook pull-in amount is an upper thread supply amount by which the upper thread 6 moves in the supply direction when the upper thread 6 is pulled by the rotary hook 39. The CPU 91 determines whether a skip has occurred depending on the output value acquired in S17 (S18). The detection period H includes a period in which the upper thread 6 moves in the supply direction when the upper thread 6 is pulled by the rotary hook 39. The thread tension plate 69 rotates in accordance with the hook pull-in amount of the upper thread 6 when the rotary hook 39 pulls in the upper thread 6. The CPU 91 of this example detects the skipping from the upper thread supply amount based on the output value of the encoder 21 in the detection period H. As shown in the lower part of FIG. 7, for example, when the CPU 91 determines that the upper thread 6 is not supplied during the detection period H based on the output value of the encoder 21 as shown in the legend V4, the rotary hook 39 does not pull the upper thread 6 in. Therefore, skipping is detected (S18: YES). At this time, the CPU 91 notifies the occurrence of an error (S19). For example, the CPU 91 controls the drive circuit 86 to display the error message “A skip was detected” on the display unit 48. The CPU 91 determines whether or not to stop driving the drive motor (S20). This determination is made according to the setting contents stored in advance in the storage device 94. When the drive motor is not stopped (S20: NO), the CPU 91 performs S22 described later. When driving the drive motor is stopped (S20: YES), the CPU 91 stops driving the drive motor (S21) and ends the sewing process.

  As indicated by the legend V3 in the middle of FIG. 7, when the CPU 91 determines that the upper thread 6 is supplied during the detection period H, the skip is not detected (S18: NO). When skipping is not detected (S18: NO), the CPU 91 determines based on the detection result of the operation button 47 whether or not a sewing end instruction, which is an instruction to end the sewing operation of the sewing machine 1, has been detected (S22). The sewing end instruction is an instruction indicating that the operator has stopped operating the pedal 38 or has finished sewing based on the sewing data. The CPU 91 continues the sewing operation until the sewing end instruction is detected (S22: NO). The CPU 91 stops driving the drive motor when the sewing end instruction is detected (S22: YES) (S23). The needle bar 11, the rotary hook 39, and the feed base 37 stop operating. The CPU 91 drives and controls the presser foot motor 43 to raise the presser foot 24 (S24), and then ends the sewing process. The cloth 99 can be taken out from the sewing machine 1.

  In the above embodiment, the sewing machine 1, the needle bar 11, the sewing mechanism 12, the thread tension mechanism 60, the thread tension plate 69, the thread tension motor 16, the output shaft 18, the encoder 21, the blade tip 36, the rotary hook 39, the hook mechanism 40, the encoder. 21, the control device 30 is an example of the sewing machine, needle bar, sewing unit, thread tension mechanism, thread tension plate, drive unit (motor), output shaft, encoder, blade tip, shuttle, shuttle mechanism, detection unit, and control unit of the present invention. It is. The operation button 47 is an example of a first input unit and a second input unit of the present invention. CPU91 which performs S10 is an example of the sewing control part of the present invention. CPU91 which performs S12 and S14 is an example of the thread tension control part of the present invention. CPU91 which performs S3 and S5 is an example of the 1st acquisition part of the present invention. The CPU 91 that executes S17 is an example of the output value acquisition unit of the present invention. CPU91 which performs S18 is an example of the judgment part of the present invention. CPU91 which performs S3 and S5 is an example of the 2nd acquisition part of the present invention.

  The sewing machine 1 of the above embodiment controls the supply of the upper thread 6 by controlling the thread tension motor 16 during sewing, and moves the upper thread 6 supplied to the balance 51 side from the thread tension mechanism 60 in the direction opposite to the supply direction. it can. By moving the upper thread 6, the sewing machine 1 can apply an appropriate tension to the upper thread 6 when the balance 51 is pulled up, and can reliably apply the necessary tension to the upper thread 6 as compared with the conventional sewing machine. Therefore, the sewing machine 1 has a stable seam during sewing as compared with the conventional sewing machine, and can suppress poor sewing.

  The sewing machine 1 includes a thread tension tray 69 around which the upper thread 6 is wound, a thread tension motor 16 that is a drive unit having an output shaft 18 that rotatably supports the thread tension tray 69, and an encoder that detects the rotation angle of the output shaft 18. 21 is provided. During the driving control of the sewing mechanism 12, the CPU 91 controls the thread tension motor 16 to rotate the thread tension tray 69 counterclockwise as viewed from the right side (S12, S14). The sewing machine 1 drives and controls the thread tension motor 16 to rotate the thread tension tray 69 in the direction opposite to the rotation direction in which the upper thread 6 is supplied, so that the upper thread 6 supplied to the balance 51 side from the thread tension tray 69 is supplied. It can move to the yarn supply part (for example, thread spool) side from the thread tension plate 69.

  The sewing machine 1 includes a rotary hook 39 having a sword tip 36 that captures a loop of the upper thread 6 inserted through the sewing needle 10, and a hook mechanism 40 that rotates the rotary hook 39 in conjunction with the vertical movement of the sewing needle 10. When the rotary hook 39 is rotated by the hook mechanism 40, the control unit removes the hook from the loop of the upper thread 6 captured by the sword tip 36 from the rotary hook 39 until the tension is applied to the upper thread 6 by lifting the balance 51. The thread tension motor 16 is driven and controlled at T1. Specifically, the sewing machine 1 drives and controls the thread tension motor 16 at the hook removal timing provided in the hook removal period T1 to move the upper thread 6 in the collecting direction. The sewing machine 1 can apply an appropriate tension to the upper thread 6 when the balance 51 is pulled up by moving the upper thread 6 supplied excessively between the thread tension plate 69 and the seam 98 in the recovery direction during the hook pull-out period T1. Sewing failure due to insufficient tension of the upper thread 6 during sewing can be suppressed.

  The sewing machine 1 is provided with an operation button 47 for driving and controlling the thread tension motor 16 to input a first rotation amount that rotates in the opposite direction during the hook pull-out period T1. CPU91 acquires the 1st rotation amount which operation button 47 inputs (S3, S5). The CPU 91 drives and controls the thread tension motor 16 during the hook pull-out period T1, and rotates the thread tension tray 69 in the opposite direction by the first rotation amount calculated in S5 (S12). In conventional sewing machines, when adjusting the tension of the upper thread, the thread take-up spring is adjusted according to the operator's intuition. When the sewing machine 1 adjusts the tension of the upper thread 6, the variable (first rotation amount) for adjusting the tension of the upper thread 6 can be quantified. Therefore, the sewing machine 1 can improve the reproducibility of adjusting the upper thread tension of the hook pull-out period T1 as compared with the conventional sewing machine. The operator can adjust the needle thread tension more easily than in the past.

  When the rotary hook 39 is rotated by the hook mechanism 40, the sewing machine 1 has a hook catching period T <b> 2 from when the tip 36 catches the upper thread 6 until the loop of the upper thread 6 caught by the blade tip 36 comes out of the rotary hook 39. The thread tension motor 16 is driven and controlled to rotate the thread tension plate 69 in the opposite direction. The sewing machine 1 can apply the necessary tension to the upper thread 6 during the hook catching period T2.

  The sewing machine 1 includes an encoder 21 that outputs an output value corresponding to the upper thread supply amount, which is the amount of movement of the upper thread 6 in the supply direction, to the control device 30. The CPU 91 controls the thread tension motor 16 during the hook catching period T2 to rotate the thread tension tray 69 in the opposite direction, and then the detection period provided until the loop of the upper thread 6 captured by the sword tip 36 comes out of the rotary hook 39. An output value corresponding to the upper thread supply amount of the upper thread 6 of H is acquired (S17). The CPU 91 determines whether or not skipping has occurred according to the output value acquired in S17 (S18). In the detection period H provided until the loop of the upper thread 6 captured by the sword tip 36 is removed from the rotary hook 39, the sewing machine 1 can accurately determine the presence or absence of skipping. Since the conventional sewing machine does not rotate the thread tension plate 69 in the opposite direction by driving and controlling the thread tension motor 16 during the hook catching period T2, the normal upper thread supply amount is, for example, the legend V1 shown in the lower part of FIG. When a jump occurs, the legend V2 shown in the lower part of FIG. The difference in the upper thread supply amount in the detection period H between the legend V3 and the legend V4 of the sewing machine 1 is larger than the difference in the upper thread supply amount in the detection period H between the legend V1 and the legend V2. Therefore, compared with the conventional sewing machine, the sewing machine 1 can accurately determine the presence or absence of skipping based on the upper thread supply amount of the detection period H.

  The sewing machine 1 is provided with an operation button 47 for driving and controlling the thread tension motor 16 and inputting a second rotation amount for rotating the thread tension plate 69 in the opposite direction during the hook catching period T2. CPU91 acquires the 2nd rotation amount which operation button 47 inputs (S3, S5). The CPU 91 drives and controls the thread tension motor 16 during the hook catching period T2, and rotates the thread tension tray 69 in the opposite direction by the second rotation amount. In conventional sewing machines, when adjusting the tension of the upper thread, the thread take-up spring is adjusted according to the operator's intuition. When the sewing machine 1 adjusts the tension of the upper thread 6, the variable (second rotation amount) for adjusting the tension of the upper thread 6 can be quantified. Therefore, the sewing machine 1 can improve the reproducibility of the upper thread tension adjustment of the hook catching period T2 as compared with the conventional sewing machine. The operator can adjust the needle thread tension as compared with the conventional case.

<Modification>
The present invention is not limited to the above embodiment. The type of sewing machine may be changed as appropriate, such as a lockstitch sewing machine or a boring machine. The sewing machine may be a household sewing machine or an embroidery sewing machine. The sewing machine may be a sewing machine in which a hook mechanism such as a chain stitch sewing machine is omitted. The thread tension mechanism may be a mechanism for feeding the upper thread. For example, the mechanism may be a known mechanism that controls the tension when the upper thread is fed. The collection direction may be changed according to the configuration of the thread tension mechanism. Depending on the configuration of the thread tension mechanism, the driving unit may be a single-phase motor, a motor having three or more phases, various electric motors such as a DC motor and a coreless motor, a solenoid, an air cylinder, and the like. The sewing machine may omit the first and second input portions. The first and second input units may have other configurations such as a dial input unit and a touch panel. The sewing machine may include a detection unit that outputs an output value corresponding to the upper thread supply amount to the control unit, in addition to the encoder that detects the rotation angle of the output shaft of the thread tension motor.

  The program for executing the sewing process of FIG. 8 may be stored in a storage device provided in the sewing machine before the sewing machine executes the program. Each of the program acquisition method, the acquisition route, and the device storing the program may be changed as appropriate. The sewing machine may receive a program executed by the processor from another device via a cable or wireless communication and store the program in a storage device. Other devices include, for example, a PC and a server connected via a network. The storage device provided in the sewing machine may be a storage device such as an HDD or an SSD.

  Each step of the sewing process of FIG. 8 is not limited to the example executed by the CPU 91, and another electronic device (for example, ASIC) may execute a part or all of the process. Each step of the above process may be distributed by a plurality of electronic devices (for example, a plurality of CPUs). Each step of the sewing process of the above embodiment can be changed in order, omitted or added as necessary. The present invention also includes a mode in which an OS or the like operating on the position specifying device performs part or all of the actual processing according to a command from the control unit of the sewing machine to realize the functions of the above embodiments.

  The sewing machine may not perform normal processing and may adjust the needle thread tension with a thread take-up spring. The sewing machine may omit S17 and S18. You may change the detection period of S16 suitably. The sewing machine may continue to drive the drive motor when skipping is detected (S18: YES). The notification method of S20 may be voice output or the like according to the configuration of the notification unit. The sewing machine may control the supply of the upper thread by controlling the drive unit at least one of the hook catching period and the hook removal period, and move the upper thread in the collecting direction opposite to the supply direction. The sewing machine may control the supply of the upper thread by controlling the drive unit at two or more timings in at least one of the hook catching period and the hook pull-out period, and may move the upper thread in the collecting direction opposite to the supply direction. .

DESCRIPTION OF SYMBOLS 1 Sewing machine 6 Upper thread 10 Sewing needle 11 Needle bar 12 Sewing mechanism 16 Thread tension motor 18 Output shaft 21 Encoder 26 Needle plate 27 Main motor 30 Control device 36 Blade tip 39 Rotary hook 40 Hook mechanism 47 Operation button 51 Balance 60 Thread tension mechanism 69 Thread Conditioning plate 91 CPU
94 Storage Device 98 Seam 99 Cloth

Claims (7)

A needle bar that can be moved up and down to attach a sewing needle and a scale that moves up and down in synchronization with the vertical movement of the needle bar and pulls up the upper thread, and forms a seam on the cloth with the sewing needle;
A thread tension mechanism for applying tension to the upper thread;
A drive unit for driving the thread tension mechanism;
In a sewing machine comprising the sewing unit and a control unit that drives and controls the drive unit,
The controller is
A sewing control unit that drives and controls the sewing unit to form the stitches on the cloth;
During the drive control of the sewing unit by the sewing control unit, from when the needle bar is positioned at the bottom dead center of the vertical movement range to when the balance is positioned at the top dead center of the vertical movement range. A sewing machine that functions as a thread tension control unit that drives and controls a drive unit to control the supply of the upper thread and moves the upper thread in a collecting direction opposite to the supply direction. A thread tension plate around which the upper thread is wound;
A motor that is the drive unit having an output shaft that rotatably supports the thread tension plate;
An encoder that detects a rotation angle of the output shaft;
The thread tension control unit drives and controls the motor to rotate the thread tension plate in a direction opposite to a rotation direction for supplying the upper thread during the drive control of the sewing unit by the sewing control unit. The sewing machine according to claim 1. A hook having a sword that captures the loop of the upper thread inserted through the sewing needle, and a hook mechanism that rotates the hook in conjunction with the vertical movement of the sewing needle;
The thread tension control unit is configured such that when the hook is rotated by the hook mechanism, a hook pull-out period from when the upper thread loop captured by the sword tip comes out of the hook until tension is applied to the upper thread by lifting the balance. The sewing machine according to claim 2, wherein the drive unit is driven and controlled. The thread tension control unit further includes a first input unit configured to input a first rotation amount for driving and controlling the motor to rotate in the opposite direction during the hook removal period,
The controller is
It further functions as a first acquisition unit that acquires the first rotation amount input by the first input unit,
The sewing machine according to claim 3, wherein the thread tension control unit drives and controls the motor during the hook removal period to rotate the thread tension tray in the opposite direction by the first rotation amount.   The thread tension control unit, during the rotation of the hook by the hook mechanism, during the hook catching period until the loop of the upper thread captured by the sword tip from the encounter where the sword tip catches the upper thread, comes out of the hook. The sewing machine according to claim 3 or 4, wherein the motor is driven and controlled to rotate the thread tension plate in the opposite direction. A detection unit that outputs to the control unit an output value corresponding to an upper thread supply amount that is a supply amount of the upper thread in the supply direction;
The controller is
The period until the loop of the upper thread captured by the sword tip is pulled out of the hook after the thread tension control unit drives and controls the motor to rotate the thread tension plate in the opposite direction during the hook capturing period. An output value acquisition unit that acquires the output value according to the upper thread supply amount;
The sewing machine according to claim 5, further functioning as a determination unit that determines whether or not a skip has occurred according to the output value acquired by the output value acquisition unit. The thread tension control unit further includes a second input unit that inputs a second rotation amount for driving and controlling the motor to rotate the thread tension plate in the opposite direction during the hook capturing period.
The controller is
Further functioning as a second acquisition unit for acquiring the second rotation amount input by the second input unit;
The sewing machine according to claim 6, wherein the thread tension control unit drives and controls the motor during the hook capturing period to rotate the thread tension tray in the opposite direction by the second rotation amount.

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