JP2009142378A - Thread tension guide of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread tension guide of a sewing machine capable of always obtaining a stable tension of thread. <P>SOLUTION: The thread tension guide 1 of the sewing machine has a thrust inverting means provided between a driving rod 4 and a thrust transmission rod 20. A weight of a movable part on the side of a thread tension device composed of a disc holder 7 and the driving rod 4, and a weight of a movable part on the side of a driving means composed of the driving means and the thrust transmission rod 20 are approximately equal. A force generated by acceleration of vibration is applied to the movable parts (on the sides of thread tension guide and on the side of the driving means) due to vibration of a head part MFAH of the sewing machine while sewing. The force is compensated by inverting a direction of the force through the thrust transmission means so that the force is prevented from acting as a pressing force (a forward disc pressing force) of the disc holder 7 for pressing the thread tension disc 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thread tension device for a sewing machine that applies tension to a thread.

  Conventionally, the sewing machine has been provided with a thread tension device that applies tension to the thread. As a kind of thread tension device of this sewing machine, a thread tensioner having a pair of thread tension plates and a plate presser capable of pinching the yarn, and a driving means for applying power for pressing the plate presser to the thread tension plate to the drive rod There is known a thread tension device for a sewing machine including: FIG. 3 is a longitudinal sectional view of a conventional thread tension device of a sewing machine viewed from the thickness direction. In such a thread tension device for a sewing machine, the pressing force applied to the thread tension tray is adjusted by the thrust of a linearly driven actuator as a driving means to control the tension applied to the thread (Patent Document 1). ).

  Hereinafter, the configuration of the conventional thread tension device 1 for a sewing machine will be described with reference to FIGS.

  As shown in FIG. 4, the sewing machine frame MF of the sewing machine M provided with the conventional thread tension device 1 has a bed portion (not shown) arranged at the lower portion and an arm extending in parallel with the bed portion (not shown) at the upper portion. The part MFA is arranged. The bed part (not shown) and the arm part MFA are connected by an arm support part MFC disposed on the base end side shown on the right side of the bed part (not shown) in FIG. Yes. The thread tension device 1 is disposed on the sewing machine head MFAH located on the free end side shown on the left side of the arm portion MFA in FIG. 4, and tensions the upper thread (not shown) on the upper thread supply source side from the balance 2. It comes to grant. As shown in FIG. 4, the thread tension device 1 is arranged at the lower right of the balance 2 and is configured so that an upper thread (not shown) from the thread tension device 1 is directly supplied to the balance 2. Therefore, the thread tension device 1 is disposed at a position that is susceptible to the vibration of the sewing machine head MFAH during sewing by a needle bar vertical driving means (not shown) provided in the sewing machine head MFAH.

  As shown in FIG. 3, the conventional thread tension device 1 includes a thread tension device 3 and driving means that applies power to the drive rod 4 to press the plate presser 7 constituting the thread tension device 3 against one thread tension plate 6 </ b> A. And the actuator 5 as described above.

  The thread tensioner 3 is a pair formed in an annular shape in which one thread tension tray 6A can be brought into contact with and separated from the other thread tension tray 6B, and an upper thread (not shown) between the thread tension trays can be held and released. Thread tension tray 6 (reference numeral 6 collectively refers to a pair of thread tension trays 6A and 6B), a plate presser 7 that is attached to the drive rod 4 and presses one thread tension tray 6A, and a plate presser 7 for positioning. A counter presser positioning nut 8 screwed into a male thread at the tip of the drive rod 4, a thread tension bar 9 for supporting the drive rod 4 with the thread tensioner 3, and a thread tension for holding the thread tensioner 3. A pole base 10 is provided.

  FIG. 5 shows an exploded perspective view of the conventional thread tensioner 3. As shown in FIG. 5, the thread tension tray 6 is inserted into the thread tension rod 9 with respective tray inner holes 6 a and 6 b formed so as to penetrate through the center of each thread tension tray 6 in the thickness direction. Thus, the thread tension bar 9 is attached so as to be movable and rotatable in the axial direction. The plate presser 7 has three claw portions 7a as contact projections formed in a substantially flat plate shape and arranged so as to be spaced from each other at an equal angle. The drive rod 4 is supported in the inner hole of the thread tension rod 9 so as to be reciprocally movable in the axial direction. The drive rod 4 penetrates both side walls (the right side wall RW and the left side wall LW) of the sewing machine head MFAH of the sewing machine M in the left-right direction and is slidably disposed in the penetration direction. A thread take-up spring 11 made of a coil spring is mounted on the thread tension bar 9 and the thread tension bar base 10. The thread tension bar 9 is provided with a detent 12 formed in a substantially cylindrical shape. On the outer peripheral surface of the rotation stopper 12, three claw locking grooves 12a extending in the axial direction are arranged at an equal angle from the center. The stopper 12 is fixed to the thread tension bar 9 by bringing the tip of a set screw (not shown) screwed into the bottom of the claw locking groove 12 a into contact with the outer peripheral surface of the thread tension bar 9. A spring mounting groove 12b is formed in the right end surface of the rotation stopper 12 so as to form an annular shape as a whole, and a plate presser holding spring 13 made of a compression spring is mounted in the spring mounting groove 12b. In addition, the opening side of the protective cover 14 formed in a substantially bottomed cylindrical shape is attached to the outer peripheral surface of the rotation stopper 12 by a set screw (not shown), and is arranged on the right side of the rotation stopper 12 and the rotation stopper 12. Covers the part.

  The actuator 5 as the driving means of the conventional thread tension device 1 uses, in particular, a voice coil motor in which the movable part side is a field magnet 15 and the stator side is a coil 16. As shown in FIG. 3, the actuator 5 houses a cylindrical winding bobbin 17 around which a coil 16 is wound, a magnet 15 for constituting a mover magnetic circuit of a voice coil motor, and a winding bobbin 17. And a cylindrical case 18 for constituting a magnetic circuit, and a mover rod 19. A drive rod 4 of the thread tensioner 3 is inserted and fixed to the mover rod 19, and the drive rod 4 is a bearing formed on the case 18 of the actuator 5 at both ends of the mover rod 19. It is supported by 26A. Further, a magnet 15 is fixed to the mover rod 19 by a fixing member such as an adhesive, and the magnet 15, the mover rod 19 and the drive rod 4 slide together. A resin material is used for the winding bobbin 17, and a ferromagnetic material is used for the case 18 and the mover rod 19 in order to form a magnetic circuit. The drive rod 4 is made of a non-magnetic material such as stainless steel in order to prevent magnetic flux generated by the magnetic circuit of the magnet 15 of the actuator 5 from leaking toward the thread tensioner 3.

Japanese Patent Laid-Open No. 2003-181182

  However, the conventional thread tension device 1 of the sewing machine having the above-described configuration has a problem that the yarn tension value varies due to the vibration of the sewing machine head MFAH during sewing.

  That is, in such a thread tension device 1, thrust by the actuator 5 is applied to the left end of the drive rod 4 inserted through the thread tensioner 3 and the actuator 5, and the thread tension plate 6 is applied to the right end of the drive rod 4. Is transmitted as a presser force of the plate presser 7 that presses. Accordingly, the direction of the presser force of the plate presser 7 (the positive direction of the plate presser force indicated by the white arrow B in FIG. 3) and the direction of the thrust generation of the actuator 5 (the actuator thrust indicated by the white arrow A in FIG. 3) The positive direction is the same direction. In such a configuration, the influence of the vibration due to the force generated by the acceleration of the vibration of the sewing machine head during sewing is supported by the case 18 of the actuator 5 and is disposed through both side walls of the sewing machine head MFAH. This is different from the actuator thrust which is a set value of the load control device applied to the driving rod 4 and applied to the thread tension plate 6. Further, since the load due to vibration varies depending on the acceleration of vibration, the yarn tension value varies.

  SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a thread tension device for a sewing machine that can always obtain a stable yarn tension.

  In order to achieve the above-mentioned object, the thread tension device of the sewing machine of the present invention according to claim 1 of the present invention is characterized in that it extends in parallel with the drive rod and can be advanced and retracted in the extending direction by the drive means. And a thrust reversing means for connecting the drive rod and the thrust transmission rod, and for reversing the thrust of the thrust transmission rod applied from the drive means in the opposite direction and transmitting the thrust to the drive rod. It is in the point. By adopting such a configuration, the direction of the force generated by the acceleration of the vibration of the head of the sewing machine can be reversed and canceled between the drive rod and the thrust transmission rod by the thrust transmission means. Therefore, the force generated by the acceleration of the vibration can be absorbed in the thread tension device without acting as a presser force of the presser foot that presses the thread tension plate (positive plate presser force).

  Further, the thread tension device of the sewing machine according to claim 2 of the present invention is characterized in that in the thrust reversing means, the weight of the thread tensioner side movable part composed of the plate presser and the drive rod, the drive means and the thrust transmission. The driving means side movable part composed of the rod is configured to have the same weight. By adopting such a configuration, the force generated by the acceleration of the vibration applied to the sewing machine movable portion can be more reliably absorbed in the thread tension device.

  As described above, according to the thread tension device of the sewing machine of the present invention according to claims 1 and 2, the thread is always stable without being affected by the thread tension due to the vibration of the sewing machine head during sewing. The tension value can be controlled, and further, it is possible to control a lower thread tension value that is more easily affected by the vibration of the sewing machine head as compared with a strong thread tension value.

  The thread tension device 1 of the present invention has a rear end portion connected to a thread tension device 3 having a drive rod 4 and a mover rod 19 of an actuator 5 as a drive means, and extends parallel to the drive rod 4. A thrust transmission rod 20 capable of moving back and forth in the extending direction, and a thrust reversing means for reversing the thrust of the thrust transmission rod 20 applied from the actuator 5 in the opposite direction and transmitting the thrust to the drive rod 4. Composed. In the present invention, the configurations of the actuator 5 and the thread tensioner 3 are the same as those of the conventional configuration described above, and the description thereof is omitted.

  FIG. 1 is a cut front view of the thread tension device 1 of the first embodiment of the present invention as seen from the thickness direction of the machine head MFAH.

  The thrust reversing means in the thread tension device 1 of the first embodiment of the present invention includes a rack gear 21A disposed at the rear end (leftward in FIG. 1) of the drive rod 4 and the tip of the thrust transmission rod 20. And a rack gear 21B disposed in the section (rightward in FIG. 1). Both rack gears 21A and 21B (symbol 21 is a generic name for a pair of rack gears) similarly constitute thrust reversing means, and are not shown with a gear 22 pivotally supported by a shaft 22A disposed in a case (not shown) so as to be freely rotatable. In a state where the gear teeth are engaged with each other, they are arranged to face each other (vertical direction in FIG. 1). The thrust transmission rod 20 is disposed so as to extend in parallel with the drive rod 4, that is, the pan presser 7 and the drive with the gear 22 supported via the shaft 22 </ b> A sandwiched between cases (not shown). A thread tensioner side movable part composed of a rod 4 and a drive means side movable part composed of an actuator 5 and a thrust transmission rod 20 are arranged, and the drive rod 4 and the thrust transmission rod 20 are different via the gear 22. It is configured to move forward and backward in the direction. In addition, it is preferable that the weight of the thread tensioner side movable portion and the driving means side movable portion are configured to be equal.

  In the first embodiment, the actuator 5 and the thrust reversing means are housed in a case (not shown), and the entirety or a part of the actuator 5 and the thrust reversing means are rear side of the sewing machine head MFAH according to the arrangement of the thread tension plate 6 of the thread tensioner 3 It is arranged.

  Next, the operation | movement about the thread tension apparatus 1 of 1st embodiment of this invention is demonstrated.

  When the actuator 5 is energized by an actuator drive circuit (not shown), a current flows through the connected coil 16. According to Fleming's left hand rule, the magnetic field of the magnet 15 on the mover side causes the current of the coil 16 to be parallel to the thrust transmission rod 20 (by changing the polarity of the current flowing through the coil 16 to the right or left in FIG. Is generated). For example, the thrust generated in the right direction (hereinafter, the right direction and the left direction indicate directions in FIG. 1) is disposed on the driving means side movable portion including the actuator 5 and the thrust transmission rod 20 and the thrust transmission rod 20. The rack gear 21B has a rightward thrust (positive actuator thrust indicated by a white arrow A in FIG. 1). The thrust in the right direction of the rack gear 21B is converted into a counterclockwise rotational torque via the gear 22, and the counterclockwise rotational torque is converted into the rack gear 21A and the plate presser 7 and the drive rod 4 arranged on the drive rod 4. It is reversed to the leftward thrust of the thread tensioner side movable part. Further, the leftward thrust transmitted to the plate presser 7 is the positive force of the plate presser 7 that presses one thread tension plate 6A that is in contact with the plate presser 7 (indicated by a white arrow B in FIG. 1). One thread tension tray 6A is pressed against the other opposite thread tension tray 6B, and an upper thread (not shown) between the pair of thread tension trays 6 is narrowed at a predetermined pressure. Be held.

  In addition, since the actuator thrust of the actuator 5 can be changed by changing the current value supplied to the coil 16, the pressure at which the upper thread (not shown) is held can be changed. At the time of sewing of the sewing machine, as the upper thread (not shown) is consumed, the upper thread (not shown) is fed from the thread tensioner 3, and thread tension is generated at this time. Therefore, even during the sewing cycle of the sewing machine, the thread tension value during the sewing cycle can be made variable by changing the value of the current supplied to the coil 16 when the upper thread (not shown) is fed.

  Next, the operation and effect of the thread tension device 1 according to the first embodiment of the present invention will be described.

  According to the thread tension device 1 of the sewing machine according to the first embodiment of the present invention, the vibration of the sewing machine head MFAH during sewing accelerates the vibration to the sewing machine movable part including the thread tensioner side movable part and the drive means side movable part. Even if the force generated by the above is applied, a thrust reversing means is provided, and further, the weight of the thread tensioner side movable part consisting of the plate presser 7 and the driving rod 4 and the weight of the driving means side movable part consisting of the driving means and the thrust transmission rod 20 are reduced. By configuring to be substantially equal, the force generated by the acceleration of vibration can be absorbed in the thread tension device.

  For example, when a rightward force due to acceleration of vibration is applied to the driving means side movable portion due to vibration of the sewing machine head MFAH, this force becomes a rightward thrust of the rack gear 21 </ b> B disposed on the thrust transmission rod 20. . The thrust in the right direction of the rack gear 21B is converted into a counterclockwise rotational torque through the gear 22. Further, the counterclockwise rotational torque is reversed to the leftward thrust of the drive rod 4 on which the rack gear 21A is disposed.

  When a rightward force due to acceleration of vibration is applied to the driving means side movable portion due to vibration of the sewing machine head MFAH, at the same time, also to the thread tensioner side movable portion in the right direction due to acceleration of vibration. Power is added.

  This force becomes a rightward thrust of the rack gear 21A disposed on the drive rod 4, and the rightward thrust of the rack gear 21A is converted into a clockwise rotational torque via the gear 22. Then, the clockwise rotational torque is reversed to the leftward thrust of the thrust transmission rod 20 provided with the rack gear 21B.

  Therefore, the rightward force applied to the drive means side movable part and the thread tensioner side movable part generated by the acceleration of vibration is simultaneously transmitted to the drive means side movable part and the thread tensioner side movable part via the gear 22. Will be offset by the force that is applied. Therefore, even if a rightward force due to the acceleration of the vibration of the sewing machine head MFAH is generated, the force is canceled as a whole, so that the presser force of the presser foot 7 that presses the thread tension tray 6 (forward presser force). It is absorbed inside the thread tension device 1 without acting. In particular, as in the present embodiment, when the weights of the driving means side movable portion and the thread tensioner side movable portion are configured to be approximately equal, the acceleration force caused by the vibration is also approximately equal, so that it can be reliably canceled out. Can be made. Even when a leftward force is applied to the driving unit side movable portion due to acceleration of the vibration of the sewing machine head MFAH, the same mechanism is used to absorb the force in the thread tension device 1.

  Therefore, according to the thread tension device 1 of the second embodiment of the present invention, it is possible to always control the thread tension value stably without being affected by the thread tension caused by the vibration of the sewing machine head MFAH during sewing. . It is also possible to control the thread tension value to a lower value that is more susceptible to the vibration of the machine head MFAH than the strong thread tension value.

  FIG. 2 is a cut front view of the thread tension device 1 of the second embodiment of the present invention as seen from the thickness direction of the machine head MFAH. Hereinafter, a second embodiment of the thread tension device 1 for a sewing machine according to the present invention will be described focusing on differences from the first embodiment.

  The thrust reversing means in the thread tension device 1 according to the second embodiment of the present invention includes a pair of pulleys 23 that are rotatably supported by a shaft 23A disposed in a case (not shown) and an outer periphery of the pair of pulleys 23. The belt 24 is wound and stretched, and a pair of fixing brackets 25A and 25B. The ends of the thrust transmission rod 20 and the drive rod 4 are respectively attached to the opposing positions (vertical position in FIG. 2) of the belt 24 wound and stretched between a pair of pulleys via fixing brackets 25A and 25B. Yes. The thrust transmission rod 20 is arranged so as to extend in parallel with the drive rod 4. Therefore, on the basis of the pair of pulleys 23 supported by the sewing machine head MFAH, the thread tensioner side movable part composed of the plate presser 7 and the drive rod 4 and the drive means side movable part composed of the drive means and the thrust transmission rod 20 The two places move. The thread tensioner side movable part and the driving means side movable part are configured to have the same weight.

  In the second embodiment of the thread tension device 1 of the present invention, as in the first embodiment, the actuator 5 and the thrust reversing means are housed in a case (not shown) and the thread tension tray 6 of the thread tensioner 3 is Depending on the arrangement, the whole or a part of the sewing machine head MFAH is arranged on the back surface.

  Next, the operation of the thread tension device 1 according to the second embodiment of the present invention will be described.

  When the actuator 5 is energized by an actuator drive circuit (not shown), a current flows through the connected coil 16. According to Fleming's left-hand rule, the magnetic field of the magnet 15 on the mover side causes the current of the coil 16 to be parallel to the thrust transmission rod 20 (by changing the position of the current flowing through the coil 16 to the right or left in FIG. Is generated). For example, the electromagnetic force generated in the right direction (hereinafter, the right direction and the left direction indicate directions in FIG. 2) is arranged on the driving means side movable portion including the actuator 5 and the thrust transmission rod 20 and the thrust transmission rod 20. This is the rightward thrust (positive actuator thrust indicated by white arrow A in FIG. 2) of the fixed metal fitting 25A. The thrust in the right direction of the fixing bracket 25A is converted into a counterclockwise rotational torque via the belt 24, and this counterclockwise rotational torque is driven by the fixing bracket 25B and the plate presser 7 disposed on the drive rod 4. The thrust is reversed to the leftward thrust of the thread tensioner side movable portion formed of the rod 4. Further, the leftward thrust transmitted to the plate presser 7 is a positive force of the plate presser 7 that presses one thread tension plate 6A that is in contact with the plate presser 7 (indicated by a white arrow B in FIG. 2). One thread tension tray 6A is brought into contact with the other opposite thread tension tray 6B, and an upper thread (not shown) between the pair of thread tension trays 6 is at a predetermined pressure. Pinched.

  In the present embodiment as well, the actuator thrust of the actuator 5 can be changed by changing the value of the current supplied to the coil 16, so the pressure (dish presser force) that holds the upper thread (not shown) is also changed. Is possible.

  Next, the operation and effect of the thread tension device 1 according to the second embodiment of the present invention will be described.

  According to the thread tension device 1 of the sewing machine according to the second embodiment of the present invention, the vibration of the sewing machine head MFAH during sewing accelerates the vibration to the sewing machine movable part including the thread tensioner side movable part and the drive means side movable part. Even if force is applied, a thrust reversing means is provided, and the weight of the thread tensioner side movable part comprising the plate presser 7 and the drive rod 4 is substantially equal to the weight of the drive means side movable part comprising the drive means and the thrust transmission rod 20. With this configuration, the force generated by the acceleration of vibration can be absorbed in the thread tension device.

  For example, when a rightward force due to acceleration of vibration is applied to the driving unit side movable portion due to vibration of the sewing machine head MFAH, this force becomes a rightward thrust of the fixing bracket 25 </ b> A connected to the thrust transmission rod 20. . The thrust in the right direction of the fixing bracket 25 </ b> A is converted into clockwise rotation torque via the belt 24. Further, the clockwise rotational torque is reversed to the thrust in the left direction of the thread tension side movable portion including the fixing bracket 25 </ b> B and the drive rod 4.

  When the rightward force due to the acceleration of vibration is applied to the driving means side movable portion by the vibration of the sewing machine head MFAH, the rightward direction due to the acceleration of vibration is also applied to the thread tensioner side movable portion at the same time. Power is added.

  This force becomes a thrust in the right direction of the fixing bracket 25B coupled to the drive rod 4, and the thrust in the right direction of the fixing bracket 25B is converted into a counterclockwise rotational torque via the belt 24. Then, the counterclockwise rotational torque is reversed to the leftward thrust of the driving means side movable portion including the fixing bracket 25 </ b> A and the thrust transmission rod 20.

  Therefore, the force in the right direction applied to the driving means side movable portion and the thread tensioner side movable portion generated by the acceleration of vibration is transmitted via the belt 24 to the thread tensioner side movable portion and the driving means side movable portion. The force transmitted to is offset with each other. Therefore, even if a rightward force due to the acceleration of the vibration of the sewing machine head MFAH is generated, the force is canceled as a whole, so that the presser force of the presser foot 7 that presses the thread tension tray 6 (forward presser force). It is absorbed inside the thread tension device 1 without acting. In particular, as in the present embodiment, when the weights of the driving means side movable portion and the thread tensioner side movable portion are configured to be approximately equal, the acceleration force caused by the vibration is also approximately equal, so that they are reliably offset. be able to. Even when a leftward force is applied to the driving unit side movable portion due to acceleration of the vibration of the sewing machine head MFAH, the same mechanism is used to absorb the force in the thread tension device 1.

  Therefore, according to the thread tension device 1 of the second embodiment of the present invention, it is possible to always control the thread tension value stably without being affected by the thread tension caused by the vibration of the sewing machine head MFAH during sewing. . It is also possible to control the thread tension value to a lower value that is more susceptible to the vibration of the machine head MFAH than the strong thread tension value.

  In addition, this invention is not limited to the said embodiment, It shall change variously as needed.

The longitudinal cross-sectional view of the thread tension device of the sewing machine which concerns on 1st embodiment of this invention Longitudinal sectional view of a thread tension device for a sewing machine according to a second embodiment of the present invention A longitudinal sectional view of a conventional thread tension device of a sewing machine The enlarged perspective view which shows the principal part of the vicinity of the sewing machine head of the conventional sewing machine Exploded perspective view of a conventional thread tensioner

Explanation of symbols

1 Thread tension device 2 Balance 3 Thread tension device 4 Drive rod 5 Actuator (voice coil motor)
6, 6A, 6B Thread tension plate 6a, b Plate inner hole 7 Plate presser 7a Claw part 8 Counter presser positioning nut 9 Thread tension bar 10 Thread tension bar base 11 Thread take-up spring 12 Detent 12a Claw locking groove 12b Spring mounting groove 13 Countersink holding spring 14 Protective cover 15 Magnet 16 Coil 17 Winding bobbin 18 Case 19 Mover rod
20 Thrust transmission rod 21, 21A, 21B Rack gear 22 Gear
22A shaft 23 pulley 23A shaft 24 belt 25, 25A, 25B fixing bracket 26A, 26B bearing M sewing machine MF sewing machine frame MFA arm part MFAH sewing machine head MFC sewing machine support part RW right side wall LW left side wall

Claims (2)

A pair of thread tension plates capable of pinching the thread, a thread tensioner attached to a drive rod and having a plate presser capable of pressing one of the thread tension plates; and In a thread tension device of a sewing machine provided with driving means for applying power to press the thread tension tray,
A thrust transmission rod that extends in parallel with the drive rod and that can be advanced and retracted in the extending direction by the drive means, and connects the drive rod and the thrust transmission rod, and is applied from the drive means. A thread tension device for a sewing machine, comprising thrust reversing means for reversing the thrust of the thrust transmission rod in the opposite direction and transmitting the thrust to the drive rod.   2. The sewing machine according to claim 1, wherein the weight of the thread tensioner side movable part composed of the plate presser and the drive rod is made equal to the weight of the drive means side movable part composed of the drive means and the thrust transmission rod. Thread tension device.

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