EP2671980A1

EP2671980A1 - Yarn twisting machine and method for starting up a drive motor

Info

Publication number: EP2671980A1
Application number: EP13166903.8A
Authority: EP
Inventors: Masaru Yamasaki; Hiroshi Yakushi; Kaname Sawanoi
Original assignee: Murata Machinery Ltd
Current assignee: Murata Machinery Ltd
Priority date: 2012-06-08
Filing date: 2013-05-07
Publication date: 2013-12-11
Also published as: CN103484988A; JP2013253355A

Abstract

A yarn twisting machine (100) includes a yarn twisting unit (50) having a plurality of yarn twisting sections (1), a power supply section (45), a plurality of changeover switches (40A~40E) respectively provided corresponding to a plurality of drive motors (14), and a main control device (2). The main control device (2) is adapted to control the changeover switches (40A~40E) corresponding to the drive motors (14) such that at the time of starting up the drive motor (14) an electric power supply to the drive motor (14) is interrupted from time to time.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a yarn twisting machine for adding twists to a yarn, and a method for starting up a drive motor provided in the yarn twisting machine.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2008-13860 , for example, discloses a yarn twisting machine adapted to add twists to a yarn. The yarn twisting machine includes a plurality of yarn twisting sections for adding the twists to the yarn. Each of the plurality of yarn twisting sections includes a rotor and a drive motor for rotating the rotor, and the twists are added to the yarn by rotation of the rotor. The yarn twisting machine is provided with one power supply section (an inverter) for supplying electric power to the plurality of drive motors. By supplying the electric power from the power supply section to the drive motors respectively provided in the plurality of yarn twisting sections, twisting process of the yarn is performed in each yarn twisting section.

SUMMARY OF THE INVENTION

As mentioned above, in a case that the yarn twisting machine is configured such that one power supply section provides the electric power to the plurality of drive motors, after stopping a drive motor of one yarn twisting section to exchange a package, when the drive motor is started up again, for example, the same electric power as supplied to another drive motor (a drive motor which is not stopped) is supplied to the relevant drive motor. Accordingly, a rotation speed of the drive motor which has been stopped, rapidly increases, and a rotor rapidly rotates at a high speed. Therefore, since behavior is not stable until a form of the yarn swung by the rotation of the rotor becomes balloon-like, yarn cut and the like may occur by a yarn making contact with a member provided on an axis of the rotor, or the like.
An object of the present invention is, at the time of starting up a predetermined drive motor in the yarn twisting machine provided with the plurality of drive motors, to provide a yarn twisting machine and a method for starting up the drive motor, that are capable of making more appropriate the form of the yarn swung by the rotor being rotated by the drive motor that has been started up.
A yarn twisting machine according to the present invention is a yarn twisting machine including a plurality of yarn twisting sections adapted to add twists to a yarn, a drive motor provided in every yarn twisting section and adapted to drive the yarn twisting section, a power supply section adapted to supply common electric power to each drive motor, and a switching section provided in every drive motor and adapted to switch between supply and interruption of the electric power supplied from the power supply section to the drive motor, the yarn twisting machine further includes a switching control section adapted to switch by operating the switching section to either of a state in which the electric power is supplied from the power supply section to the drive motor or a state in which the electric power supply is interrupted. The switching control section, at the time of starting up at least one of the yarn twisting sections (1) in a state that at least one yarn twisting section (1) of the other yarn twisting sections (1) is being driven, controls the switching sections (40A∼40E) such that the electric power supply to the drive motor (14) of the yarn twisting section (1) to be started up is interrupted from time to time.
A method for starting up a drive motor according to the present invention is a method for starting up a drive motor of a yarn twisting machine that includes a plurality of yarn twisting sections adapted to add twists to a yarn, a drive motor provided in every yarn twisting section and adapted to drive the yarn twisting section, a power supply section adapted to supply common electric power to each drive motor, and a switching section provided in every drive motor and adapted to switch between supply and interruption of the electric power supplied from the power supply section to the drive motor, and at the time of starting up at least one yarn twisting section (1) in a state that at least one yarn twisting section (1) of the other yarn twisting sections (1) is being driven, performs a process of supplying the electric power by operating the switching section from the power supply section to the drive motor to be started up, and a process of interrupting the electric power supply by operating the switching section from the power supply section to the drive motor to be started up.
According to these inventions, by controlling the switching section such that at the time of starting up the drive motor, the state is included in which the electric power supply to the drive motor is interrupted, the rotation speed of the drive motor at the time of starting up can be slowed down. In this manner, since the rotation speed of the drive motor can be prevented from rapidly rising, a form of the yarn swung by a rotor being rotated by the drive motor that has been started up can be more appropriate when starting up a predetermined drive motor. Furthermore, in a state that at least one yarn twisting section is being driven, when starting up any one yarn twisting section of the other yarn twisting sections, the rotation speed of the drive motor of the yarn twisting section, which is to be started up, at the time of starting up can be set to a predetermined speed. In this manner, regardless of a state of the yarn twisting sections other than of the yarn twisting section with the drive motor to be started up, increase of the rotation speed of the drive motor of the yarn twisting section, which is to be started up, at the time of starting up can be controlled.
The switching control section preferably controls the switching section such that in a process of increasing the rotation speed of the motor drive to a set rotation speed, a state is included a plurality of times in which the supply of the electric power to the drive motor to be started up is interrupted. In this manner, since the switching section is controlled so as interrupt the electric power for a plurality of times, the rotation speed of the drive motor at the time of starting up can be set to the predetermined speed. Accordingly, at the time of starting up the drive motor, the form of the yarn swung by the rotor being rotated by the drive motor that has been started up can be made even more appropriate.
The switching control section preferably controls the switching section such that the supply and interruption of the electric power are repeated at a same time interval until the rotation speed of the drive motor of the yarn twisting section to be started up reaches the set rotation speed. In this case, the drive motor can be favorably controlled by a simple control method until the drive motor reaches the set rotation speed.
The switching control section preferably controls the rotation speed of the drive motor by individually controlling each switching section such that at the time of starting up the drive motor, the electric power supply from the power supply section to the drive motor of the yarn twisting section to be started up is interrupted from time to time. In this manner, control of the rotation speed of the drive motor becomes possible merely by controlling the switching section so as to interrupt the electric power supply is interrupted.
According to the present invention, in the yarn twisting machine provided with the plurality of drive motors, when starting up the predetermined drive motor, the form of the yarn swung by the rotor being rotated by the drive motor that has been started up can be made more appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating a yarn twisting machine according to an embodiment of the present invention.
FIG. 2 is a view roughly illustrating a power supply system and a control configuration of a drive motor.
FIG. 3 is a view illustrating a rotation speed of one drive motor and a control state of a changeover switch in case of starting up one drive motor in a state wherein another drive motor is being driven.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A preferred embodiment of a yarn twisting machine and a method for starting up a drive motor according to the present invention will be hereinafter described in detail with reference to the drawings. The same reference numerals are used for on the same or corresponding elements throughout the drawings, and redundant description will be omitted.
FIG. 1 is a view schematically illustrating a yarn twisting machine according to the present embodiment. A yarn twisting machine 100 according to the present embodiment is configured including a yarn twisting unit 50, a main control device (switching control device) 2 adapted to control actuation of the yarn twisting unit 50. The yarn twisting unit 50 includes a plurality of yarn twisting sections 1 being arranged side by side. FIG. 1 represents in a front view only one yarn twisting section 1 of the plurality of yarn twisting sections 1 included in the yarn twisting unit 50.
The yarn twisting section 1 twists two yarns together. The yarn twisting section 1 includes an inner yarn supplying package supporting section 3 adapted to support a yarn supplying package (hereinafter referred to as an "inner yarn supplying package P1") for supplying one of two yarns to be twisted together (hereinafter referred to as an "inner yarn Y1"), an outer yarn supplying package supporting section 4 adapted to support a yarn supplying package (hereinafter referred to as an "outer yarn supplying package P2") for supplying the other yarn (hereinafter referred to as an "outer yarn Y2"), a tension applying device 5 adapted to apply tension to the outer yarn Y2, and a winding device 6 adapted to wind a doubled yarn Y as a yarn in which the inner yarn Y1 and the outer yarn Y2 are twisted together. Furthermore, the yarn twisting section 1 is provided with a balloon forming device 7 upstream the inner yarn supplying package supporting section 3, being on a same axis with the inner yarn supplying package supporting section 3. The balloon forming device 7 is adapted to form a balloon of the outer yarn Y2 in an outer periphery of the inner yarn supplying package supporting section 3.
First, a configuration of the yarn twisting section 1 will be described along a yarn path from where the outer yarn Y2 is fed from the outer yarn supplying package P2 to the winding device 6. The outer yarn Y2 unwound from the outer yarn supplying package P2 that is unrotatably supported by the outer yarn supplying package supporting section 4 is introduced to the tension applying device 5 orderly through a first yarn guide 8 having a function of applying some tension to the outer yarn Y2, a gate-type tensor 9 for applying a predetermined tension to the outer yarn Y2, and a second yarn guide 10. The outer yarn Y2 to which favorable tension has been applied by the tension applying device 5 is introduced to the balloon forming device 7 as if being sucked in a vertical direction orderly through a third yarn guide 11 and a fourth yarn guide 12.
The balloon forming device 7 is configured including a drive motor 14 of which output shaft is a spindle 13, and a disc (rotor) 15 fixed to the spindle 13. A yarn path where the outer yarn Y2 can pass through is formed in a shaft center of the spindle 13, and while the outer yarn Y2 that has been guided into the yarn path of the spindle 13 through the fourth yarn guide 12 is fed to outside the spindle, the outer yarn Y2 is swung whirling along a lower surface of the disc 15 since the disc 15 is rotated by the drive motor 14 through the spindle 13. The outer yarn Y2 fed from the spindle 13 is further guided to an outer periphery of the disc 15 crawling on the lower surface of the disc 15, and introduced to the winding device 6 while whirling and expanding around a package container 18 that accommodates the inner yarn supplying package P1.
A configuration of the inner yarn supplying package supporting section 3 will be described. The inner yarn supplying package supporting section 3 supports the inner yarn supplying package P1 and the package container 18 accommodating the inner yarn supplying package P1. The inner yarn supplying package supporting section 3 is rotatably supported to the spindle 13 through a bearing, and its rotation is regulated by magnetic coupling with a magnet being arranged on the outer periphery of the inner yarn supplying package supporting section 3. Accordingly, the inner yarn supplying package P1 and the package container 18 remain in a stationary state even when the spindle 13 is rotated. The package container 18 prevents the outer yarn Y2 fed from below from making contact with the inner yarn supplying package P1.
On the other hand, the inner yarn Y1 unwound from the inner yarn supplying package P1 is guided to a fifth yarn guide 20 after being guided to the center axis of the shaft by a sixth yarn guide 21.
Next, a configuration of the winding device 6 will be briefly described. The winding device 6 includes, in order along a yarn path of the doubled yarn Y, the fifth yarn guide 20 adapted to double the inner yarn Y1 and the outer yarn Y2, a yarn feeler 16 adapted to detect a state of a travelling doubled yarn Y, a tension relaxing section 22 adapted to lower tension of the doubled yarn Y by a predetermined amount, a traverse device 23 adapted to traverse the doubled yarn Y to a winding bobbin B, a cradle 24 adapted to rotatably support the winding bobbin B, and the winding drum 25 adapted to rotate the winding bobbin B being supported by the cradle 24.
In the present embodiment, the traverse device 23 is configured to traverse the doubled yarn Y to the winding bobbin B with reciprocating movement of a traverse guide that grips the doubled yarn Y. The traverse guide and the winding drum 25 are connected between the plurality of yarn twisting sections 1, and a traverse motor 26 adapted to reciprocate the traverse guides of all yarn twisting sections 1 and a winding drum motor 27 adapted to commonly rotate the winding drums 25 of all yarn twisting sections 1 are provided in one end of the yarn twisting unit 50.
The main control device 2 is connected to the drive motor 14, the yarn feeler 16, or the like that are provided in each of the plurality of yarn twisting sections 1, and the traverse motor 26, the winding drum motor 27, or the like that are commonly (singly) provided in the plurality of yarn twisting sections 1, and the main control device 2 is capable of controlling a rotation speed of the drive motor 14 and appropriately acquiring the state of the travelling doubled yarn Y by monitoring the yarn feeler 16 at a predetermined time interval such as an interval of 100 msec.
Next, actuation of the yarn twisting machine 100 will be described. When starting the operation of the yarn twisting machine 100, the outer yarn Y2 is threaded so as to form a yarn path illustrated by a solid line in FIG. 1 and guided from the outer yarn supplying package P2 to the winding bobbin B while the inner yarn Y1 is drawn from the inner yarn supplying package P1 and guided from the inner yarn supplying package P1 to the winding bobbin B. At this time, all of the traverse motor 26, the winding drum motor 27 and the drive motor 14 are kept in a stationary state.
Next, a worker inputs various operating conditions into the main control device 2 through an input means. As the various operation conditions, for example, there are a winding speed of the winding device 6, a traverse speed of the traverse device 23, the rotation speed of the spindle 13, a yarn type, a yarn thickness or the like.
The main control device 2 starts winding the doubled yarn Y by controlling the winding device 6 based on the above-described operating conditions, and accelerates the rotation of the spindle 13 by controlling the drive motor 14 until the rotation reaches an intended rotation speed. Accordingly, the outer yarn Y2, as illustrated by a one-dot chain line, moves away from an outer peripheral surface of the package container 18 and bulges out to the outer periphery of the package container 18 to form the balloon.
Since the outer yarn Y2 is swung around the outer periphery of the package container 18, the outer yarn Y2 is twisted together with the inner yarn Y1 just before reaching the fifth yarn guide 20, and the doubled yarn Y is formed. With a state of doubled yarn being maintained, tension is reduced by a predetermined amount in the tension relaxing section 22 while a state of the doubled yarn Y is being detected by the yarn feeler 16, and the doubled yarn Y is wound around the winding bobbin B while being traversed by the traverse device 23.
Next, a power supply system and a control configuration of the drive motor 14 provided in each of the plurality of the yarn twisting sections 1 will be described. FIG. 2 is a view roughly illustrating the power supply system and the control configuration of the drive motor. In FIG. 2, a part (five sections) of the plurality of the yarn twisting sections 1 is illustrated. For convenience sake, description will be made hereinafter provided that five yarn twisting sections 1 are arranged in the yarn twisting machine 100.
When the five yarn twisting sections 1 illustrated in FIG. 2 are required to be distinguished, description will be made by respectively referring to the five yarn twisting sections 1 as yarn twisting sections 1A, 1B, 1C, 1D, and 1E for convenience. Similarly, when the drive motors 14 that are respectively provided in the five yarn twisting sections 1 illustrated in FIG. 2 are required to be distinguished, description will be made by respectively referring to the five drive motors 14 as drive motors 14A, 14B, 14C, 14D, and 14E for convenience.
The main control device 2 for controlling an entire yarn twisting machine 100 is configured with a CPU (Central Processing Unit) which is an arithmetic processing device, a ROM (Read-Only Memory) for storing program to be performed by the CPU and data used for the program, a RAM (Random Access Memory) for temporarily storing data at the time of performing the program, or the like. The main control device 2 controls operation of each section of the yarn twisting machine 100 such as the traverse motor 26, the winding drum motor 27 in addition to the drive motor 14 of each yarn twisting section 1.
As illustrated in FIG. 2, the drive motors 14A∼14E are supplied with the electric power from the power supply section 45 provided in the yarn twisting machine 100 through each changeover switch (switching section) 40A∼40E. The drive motors 14A∼14E are connected in parallel to the power supply section 45. As the drive motor 14A∼14E, a three-phase induction motor may be used, for example. As the power supply section 45, a power supply source in which an inverter device is embedded may be used, for example.
Each changeover switch 40A∼40E functions as a switch for switching between supply and interruption of the electric power supplied to the drive motors 14A∼14E. As the changeover switch 40A∼40E, a magnet contactor may be used, for example. The control of the supply and interruption of the electric power in the changeover switches 40A∼40E is performed by the main control device 2.
The yarn twisting machine 100 is provided with operation switches 41A∼41E respectively corresponding to the yarn twisting sections 1A∼1E. The operation switches 41A∼41E are connected to the main control device 2. Each operation switch 41A∼41E is for instructing start and stop of driving the drive motors 14A∼14E. Therefore, the operation switches 41A∼41E are provided in an appropriate position for the worker to easily perform the operation.
Accordingly, in a state that all the drive motors 14A∼14E are being actuated, for example, the worker can stop only a specific drive motor 14A∼14E by operating any of the operation switches 41A∼41E. The worker can actuate the stopped drive motor 14A∼14E again by operating the operation switches 41A∼41E.
Next, control of the changeover switches 40A∼40E by the main control device 2 will be described in detail. The description will be made herein on the control at the time of starting up the drive motor 14E in a state that the drive motors 14A∼14D are being actuated and that only the drive motor 14E is being stopped. In FIG. 3, the rotation speed of one drive motor and a control state of a changeover switch in a case of starting up one drive motor in a state that another drive motor is being driven. The worker issues an instruction to start actuating the drive motor 14E by operating the operation switch 41E at the time of 0 illustrated in FIG. 3. In the present embodiment, starting up the drive motor 14E indicates a state in which the drive motor 14E is acceleratingly rotated to a rotation speed of steady operation from a stopped state. Driving the drive motor 14E indicates a state of rotating at a rotation speed of steady operation set by an operator.
As illustrated in FIG. 3, at the time of starting up the stopped drive motor 14E, the main control device 2 controls the changeover switch 40E such that in the process of increasing the rotation speed of the drive motor 14E to a predetermined set value (a set rotation speed), a state is included in which the electric power supply to the drive motor 14E is interrupted. Specifically, the main control device 2 controls the changeover switch 40E such that the supply of the electric power to the drive motor 14E and the interruption of the electric power (process of interrupting the electric power supply) are alternately repeated with the lapse of time.
Accordingly, the rotation speed of the drive motor 14E is increased between time 0 and time T1, between time T2 and T3, between time T4 and time T5, and between time T6 and time T7, in which the electric power is supplied in a process of supplying the electric power. The rotation speed of the drive motor 14E becomes the set value at time T7. On the other hand, the rotation speed of the drive motor 14E is not increased between time T1 and time T2, between time T3 and time T4, and between time T5 and time T6, in which the electric power supply is interrupted. In the present embodiment, a time interval of supplying the electric power and a time interval of interrupting the electric power supply are the same. However, this time interval is an example, and the time interval may be changed in accordance with a rotation state of the drive motor or the like.
Therefore, as illustrated by line X in FIG. 3, the rotation speed of the drive motor 14E is gradually increased between time 0 and time T7.
Description will be made on a change in the rotation speed of the drive motor 14E when the electric power supply is not interrupted by the changeover switch 40E in the process of increasing the rotation speed of the drive motor 14E from the stopped state of the drive motor to the predetermined set value. In this case, since the same electric power as the electric power supplied to the drive motors 14A∼14D is supplied to the drive motor 14E, as illustrated by line Z in FIG. 3, the rotation speed of the drive motor 14E is rapidly increased from time 0.
In this manner, by controlling the changeover switch 40E such that at the time of starting up the drive motor 14E, the electric power supply is interrupted from time to time, a time in which the rotation speed of the drive motor 14E becomes the set value is longer compared to a case of not interrupting the electric power supply (a case illustrated by the line Z in FIG. 3).
By adjusting by the changeover switch 40E a time width of the electric power supply, a time width of the electric power interruption, a frequency of interrupting the electric power, or the like, the rotation speed of the drive motor 14E can be slowly increased to an intended state.
Although the case of starting up the drive motor 14E is described above, also by starting up the other drive motors 14A∼14D in such manner as starting up the drive motor 14E, rotation speed at the time of starting up can be controlled.
The present embodiment is configured as described above, since the changeover switches 40A∼40E are controlled such that at the time of starting up one drive motor 14 in the state that the other drive motors 14 are being driven, the electric power supply to the one drive motor 14 is interrupted from time to time, the increase of the rotation speed at the time of starting up of the one drive motor 14 to the predetermined rotation speed can be slowed down.
In this manner, since the rotation speed of the drive motor 14 at the time of starting up can be prevented from rapidly rising, at the time of starting up the one drive motor 14 in the state that the other drive motors 14 are being driven, a form of the outer yarn Y2 swung by the disc 15 being rotated by the drive motor 14 can be more appropriate. Therefore, a failure such as a cut of the outer yarn Y2 can be prevented from occurring.
The main control device 2 controls the changeover switches 40A∼40E such that in the process of increasing the rotation speed of the drive motor 14, the state is included a plurality of times in which the electric power supply to the one drive motor 14 is interrupted. Accordingly, at the time of starting up the drive motor 14 in the state that the other drive motors 14 are being driven, the form of the outer yarn Y2 swung by the disc 15 being rotated by the one drive motor 14 can be made even more appropriate.
In the present embodiment, since the main control device 2 individually controls the rotation speed of the drive motors 14 at the time of starting up by controlling the changeover switches 40A∼40E, the rotation speed of the drive motor 14 of the yarn twisting section 1, which is to be started up, at the time of starting up can be controlled regardless of a state of the yarn twisting sections 1 other than the yarn twisting section 1, the drive motor 14 of which is to be started up.
The main control device 2 controls the changeover switches 40A∼40E such that the time interval of supplying the electric power becomes the same as the time interval of interrupting the electric power supply. In this case, the drive motor 14 can be favorably controlled by a simple control method until the rotation speed of the drive motor 14 reaches the predetermined set value.
Since the main control device 2 individually controls each changeover switch 40A∼40E such that the electric power supply to the drive motor 14 is interrupted from time to time, control of the rotation speed of the drive motor 14 becomes possible.
One embodiment of the present invention has been described thus far, however, the present invention is not limited to the above-described embodiment. In the yarn twisting machine 100, for example, various changes may be made to a part other than a configuration in which the rotation speed of the drive motor 14 is controlled.
In the above-described embodiment, a case of starting up the drive motor 14 of one yarn twisting section 1 is described as an example, however, the above-described control may be performed also when simultaneously starting up the drive motors 14 of all the yarn twisting sections 1, for example. Furthermore, the above-described control may be performed also when starting up a drive motor 14 of a predetermined yarn twisting section 1 in a state in which other yarn twisting sections 1 are being stopped.
In the above-described embodiment, description is made on a case of controlling the changeover switches 40A∼40E such that the electric power supply to the drive motor 14 is interrupted for the plurality of times, however, interrupting the electric power supply at least one time is sufficient.

Claims

A yarn twisting machine (100) comprising:
a plurality of yarn twisting sections (1) adapted to add twists to a yarn,

a drive motor (14) provided in every yarn twisting section (1) and adapted to drive the yarn twisting section (1),

a power supply section (45) adapted to supply common electric power to each drive motor (14), and

switching sections (40A∼40E) provided in every drive motor (14) and adapted to switch between supply and interruption of the electric power supplied from the power supply section (45) to the drive motor (14), the yarn twisting machine (100) further comprising a switching control section (2) adapted to switch by operating the switching sections (40A∼40E) to either of a state in which the electric power is supplied from the power supply section (45) to the drive motor (14) or a state in which the electric power supply is interrupted,
characterized in that the switching control section (2) controls the switching sections (40A∼40E) such that at the time of starting up at least one yarn twisting section (1) in a state that at least one yarn twisting section (1) of the other yarn twisting sections (1) is being driven, the state is included in which the electric power supply to the drive motor (14) of the yarn twisting section (1) to be started up is interrupted.
The yarn twisting machine (100) according to claim 1, characterized in that the switching control section (2) controls the switching sections (40A∼40E) such that in the process of increasing a rotation speed of the drive motor (14) to a set rotation speed, the electric power supply to the drive motor (14) to be started up is interrupted a plurality of times.
The yarn twisting machine (100) according to claim 2, characterized in that the switching control section (2) controls the switching sections (40A∼40E) such that the supply and interruption of the electric power are repeated at a same time interval until the rotation speed of the drive motor (14) of the yarn twisting section (1) to be started up reaches the set rotation speed.
The yarn twisting machine (100) according to any one of claims 1 to 3, characterized in that the switching control section (2) controls the rotation speed of the drive motor (14) by individually controlling each switching section (40A∼40E) such that at the time of starting up the drive motor (14), the electric power supply from the power supply section (45) to the drive motor (14) of the yarn twisting section (1) to be started up is interrupted from time to time.
A method for starting up a drive motor of a yarn twisting machine (100), which includes a plurality of yarn twisting sections (1) adapted to add twists to a yarn, a drive motor (14) provided in every yarn twisting section (1) and adapted to drive the yarn twisting section (1), a power supply section (45) adapted to supply common electric power to each of the drive motors, and switching sections (40A∼40E) provided in every drive motor (14) and adapted to switch between supply and interruption of electric power supplied from the power supply section (45) to the drive motor (14),
characterized in that a step of supplying the electric power by operating the switching sections (40A∼40E) from the power supplying section (45) to the drive motor (14) to be started up, and a step of interrupting the electric power supply by operating the switching section (40A∼40B) from the power supply section (45) to the drive motor (14) to be started up, are performed at the time of starting up at least one yarn twisting section (1) in a state that at least one yarn twisting section (1) of the other yarn twisting sections (1) is being driven.
The method according to claim 5, characterized in that the rotation speed of the drive motor (14) is controlled by individually controlling each switching section (40A∼40E) such that the electric power supply to the drive motor (14) of the yarn twisting section (1) to be started up is interrupted from time to time.