JPH08225248A - Method and device for buffering vibration of brake disk of thread tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the vibration or flattering of a brake disk caused by a thread defect. SOLUTION: The acceleration of at least one brake disk 2 being axially moved in a direction away from a thread 11 is detected, and in a direction opposite that of the acceleration of the brake disk, a force 20 proportional to this acceleration is applied on at least one brake disk 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention consists of two braking discs located opposite one another, the braking of at least one of which is carried out when a yarn having a defect as an abnormally thick spot passes between these two braking discs. The invention relates to a method for damping vibrations acting on at least one braking disk of a thread tensioner of the type in which the disk is arranged axially displaceable, and a device for carrying out this method.

[0002]

2. Description of the Prior Art Winders with winding speeds far exceeding 1000 m / min at present and up to 2000 m / min for certain yarns have yarn defects as abnormally thick spots, such as knots, nep and The fluff carried by the yarn causes a trouble in the yarn running. This obstacle consists in particular of two braking discs located opposite one another, at least one of which is displaceably arranged with respect to the other and at least one of the displaceably arranged braking discs. This is especially true of yarn tensioners of the type in which the discs are pressed against the braking discs located oppositely by the action of force.

When the above-mentioned yarn defect passes at high speed between both braking discs of the yarn tensioner, both braking discs are impulsively pressed in the separating direction. Both braking discs lose contact with each other in a short period of time, and the yarn to which the braking force is applied in order to produce the proper yarn tension passes unbridled between the two braking discs. In that case, only the ballooning tension is applied to the yarn. Therefore, the yarn tension sensor, which is in contact with the yarn and should control the crimping force of the braking disk via the registered yarn tension, may cause erroneous control because the yarn tension does not occur.

Due to the restoring force acting on the braking discs, the braking discs abut each other at high speed, and when the kinetic energy is high, the elastic disc impact causes the braking discs abutting each other to vibrate. If the brake disc of 1 again separates from the other brake disc, another obstacle occurs. This vibration or flutter of the braking disc causes a constant and repeated interruption of the braking force acting on the yarn, which is a significant obstacle to winder operation. Repeated impacts on the yarn result in yarn breakage, or the yarn forms a yarn loop, passes through the yarn tensioner and reaches the take-up bobbin, causing a take-up defect at that location.

For example, German Patent Publication No. 412
No. 9803, it is known to measure the yarn tension variation of the yarn to be wound up and to control the crimping force of the braking disk of the yarn tensioner on the basis of this, but this known device does not rewind the yarn. The above-mentioned deficiencies of time cannot be avoided.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to improve the known thread tensioners so as to avoid the abovementioned obstacles significantly.

[0007]

SUMMARY OF THE INVENTION The method of the present invention, which has solved the above-mentioned problems, detects the acceleration of a braking disc as at least one movable braking disc moves axially in a direction away from the thread. The braking disk is characterized in that a force proportional to this acceleration is applied in the direction opposite to the axial movement direction. The device according to the invention for carrying out this method comprises two braking discs located next to one another, at least one of which is arranged axially displaceable with respect to the other of the at least one disc. In a yarn tensioner of the type in which a force generator that generates a braking force is provided on an axially movable braking disc, in order to determine the acceleration of the braking disc when passing a yarn having a defect as an abnormal thick portion A sensor is provided for detecting the acceleration of the at least one movable braking disc moving in the opening direction, the sensor cooperating with the control device, and the control device comprising:
It is characterized in that it is connected to a means for generating a force proportional to the acceleration in a direction opposite to the acceleration direction of the braking disk.

In the thread tensioner, the braking disk is abnormally thick as a thread defect, for example, a nep, a loop or a node is impulsively pressed in directions away from each other and at least one axially movable braking disk is significantly accelerated. If so, the acceleration of this braking disc is detected according to the invention. If both braking discs are movably arranged and movable relative to one another, the acceleration is detected from any one of the braking discs. According to the invention, it is avoided that the braking disc is vibrated or flutters due to yarn defects. If acceleration of one or both braking discs occurs, a force proportional to this acceleration is applied to one or both braking discs. Based on the law that force is equal to the product of mass and acceleration, the force acting on the braking disc must be increased in proportion to the increase in acceleration in order to avoid mutual separation of the braking discs. The mass of the braking disc is a constant. In this way, the braking disc that is moved by the abnormal yarn defect is immediately braked. When the acceleration has disappeared, the force to be exerted on the yarn in order to apply the desired yarn tension is reapplied fully. This causes the braking disc to contact the thread.

The force acting on the braking disc is generated according to the invention by a magnet mechanism. Pneumatic or hydraulic mechanisms can be used as well. The magnet mechanism has a compact structure and does not require a connection for the supply of pressure medium. This advantageously saves space.

The at least one movable braking disk comprises a moving coil, which is immersed in a coaxial ring coil. The controller controls the current flowing in the moving coil and thus the force acting on the braking disc. It is also possible to use a magnet mechanism in which the magnet surrounding the moving coil is a permanent magnet. Furthermore, it is possible to equip the braking disc with permanent magnets immersed in a ring coil which is capable of controlling the coil current for the generation of a magnetic field. If a magnet mechanism is already present which produces the braking force to be applied to the braking disc, this magnet mechanism can be used. In that case, it is only necessary to provide a control circuit for monitoring the acceleration of the braking disc or discs.

Accelerometers can be used to detect the acceleration of the braking disc or discs. However, it is also possible to evaluate the voltage induced in the magnet arrangement by a moving coil or by a permanent magnet arranged on the braking disc. Monitoring of the acceleration of the braking disc or discs, which requires its own sensor, is not necessary according to the last-mentioned evaluation mechanism.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the illustrated principle drawings.

Only the parts necessary for understanding the present invention are shown in the drawings. The thread tensioner 1 comprises two braking discs 2, 3, which are located with their end faces 2a, 3a facing each other. Axis 4
The bearing of the braking disc 3 with is not shown here. The braking disc 3 itself is brought into contact with the other braking disc 2 by a crimping mechanism (not shown).
The braking disc can also be rotatably mounted.

Embodiments for bearing the brake discs are known in the art, for example German patent DE 293064.
No. 1 or German Federal Republic of Germany No. 2,954,571. According to DE-A-4129803, there is a magnetic coupling between the two braking discs, so that the braking disc to be driven is placed opposite the other braking disc. A thread tensioner is known in which a disk is attracted by a magnet mechanism and its rotational motion is transmitted to the other braking disk by magnetic force.

Since a mechanism for applying the force necessary for generating the thread tension to the braking disc is likewise known from the above-mentioned document,
It will not be described in detail here.

A shaft 5 is connected to the braking disk 2, which penetrates a magnet mechanism 6. The magnet mechanism 6 is composed of a ring magnet 7 having a moving coil 9. The ring magnet 7 can be composed of an electromagnet or a permanent magnet. The yoke 8 of the magnet is formed in a capsule shape. In the inner chamber 8a of the yoke 8, the moving coil 9 arranged on the braking disc 2 is immersed. The shaft 5 of the braking disc 2 penetrates through the bottom portion 8b of the capsule-shaped yoke 8 and projects therefrom. The end 5a of the shaft 5 projects into the sensor 10, and the acceleration of the braking disk 2 is detected by this sensor. Accelerometers are commercially available and are known in the art. However, for example, the acceleration of the braking disc may be monitored by a sensor that operates on the basis of light intensity fluctuations. In that case, the increase in shadow per unit time is a measure for the acceleration of the braking disc 2.

In this embodiment, the thread 11 is pulled through both braking discs 2, 3 in the direction indicated by the arrow 12. The drawing shows the moment when a yarn defect 13, in this case an abnormally thick spot, is pulled through between both braking discs 2, 3. This suddenly-thickened thick portion pushes at least one movable braking disc 2 away from the other braking disc 3 in the direction indicated by arrow 14 with a large acceleration. At this time, the end 5 a of the shaft 5 of the braking disc 2 moves inside the sensor 10. In this sensor as an optical sensor, the shadows that occur per unit time are detected.
The acceleration signal is supplied to the control device 15 via the signal line 10a. An acceleration limit value 16 can be preset in the control device 15. When an acceleration signal that exceeds this acceleration limit value is generated, a damping of vibrations that may occur in the braking disk when an abnormal yarn defect is passed is introduced. The control signal is applied to the amplifier 18 via the signal line 17. The amplified signal is guided via the control line 19 to the moving coil 9, which produces a magnetic force proportional to the acceleration in response to a corresponding current, which causes the braking disc 2 to move. This force acts in the opposite direction to the direction of movement of the braking disc 2 indicated by arrow 14, as indicated by arrow 20.

When the acceleration is reduced to zero, the braking force required to generate the yarn tension is fully applied to the braking disks 2 and 3. As a result, the braking disc 2 is returned to its initial position and presses the thread 11. However, in that case, if the braking disc 2 is accelerated significantly, the braking disc 2 may collide with the other braking disc 3 and may be separated from the braking disc 3 again.

By generating a force proportional to the acceleration of the braking disc 2 and in the direction opposite to its direction of motion, vibrations of the braking disc which adversely affect the yarn quality can be advantageously prevented.

In order to generate the braking force necessary to generate the yarn tension, the yarn tension is first detected and then another control circuit is provided which controls the crimping force of the braking disc by means of the yarn tension, even if provided. A magnet mechanism can be used. For that purpose, a sensor capable of detecting the thread tension is required. A sensor capable of this and the control circuit required for the determination of the thread tension are known, for example, from DE-A-4129803. In the embodiment shown in FIG. 2 of this known document, the coupling between the tension sensor and the thread tensioner is shown as a principle diagram.

[0021]

As described above, according to the present invention,
It is avoided that the braking disc is vibrated or flutters due to yarn defects.

[Brief description of drawings]

FIG. 1 is a principle circuit diagram of the present invention.

[Explanation of symbols]

1 thread tensioner, 2,3 braking disc, 2a,
3a end face, 4,5 axis, 5a end part, 6 magnet mechanism, 7 ring magnet, 8 yoke, 8b
Bottom part, 9 moving coil, 10 sensor, 1
0a signal line, 11 thread, 12 arrow, 13
Yarn defect, 14 arrow, 15 control device, 16
Acceleration limit value, 17 signal line, 18 amplifier,
19 control lines, 20 arrows

Claims (7)

[Claims] 1. At least one of the braking discs in the axial direction is formed by two yarns which are located opposite one another and which have a defect as an abnormally thick spot between the two braking discs. Method for damping vibrations acting on at least one braking disc of a thread tensioner of the displaceably arranged type, the braking disc being provided with at least one movable braking disc axially moving away from the yarn Is detected, and a force proportional to this acceleration is applied to the braking disk in the direction opposite to the axial movement direction, and the vibration of the braking disk of the yarn tensioner is damped. 2. A method according to claim 1, wherein a force proportional to the acceleration of the braking disc is generated by a magnet mechanism. 3. The method according to claim 1, wherein a magnet mechanism provided for generating a normal braking force is used to generate a force proportional to the acceleration of the braking disk. 4. The method according to claim 1, wherein the acceleration of the at least one axially displaceable braking disc is detected via an acceleration sensor. 5. The acceleration of at least one axially displaceable braking disc is detected via an evaluation of the voltage induced in the magnet arrangement by the movement of the braking disc.
4. The method according to any one of 1 to 3. 6. To carry out the method according to any one of claims 1 to 5, it is provided with two braking discs located next to one another, at least one braking disc relative to the other braking disc. In a yarn tensioner of a type in which a force generator that generates a braking force is provided on at least one axially movable braking disk, the defect as an abnormal thick portion ( A sensor (10) for detecting the acceleration of at least one movable braking disc (2) moving in the opening direction (14) is provided to determine the acceleration of the braking disc upon passage of the yarn with 13). The sensor (10) cooperates with a control device (15), and the control device applies a force (20) proportional to the acceleration to the acceleration of the braking disc (2). Direction (14)
A yarn tensioner characterized in that it is connected to a means (6) for generating in the opposite direction. 7. Thread tensioner according to claim 5, wherein the means for generating a force (20) proportional to the acceleration of the braking disc (2) comprises a magnet mechanism (6).