Twisting method and twisting frame

The invention relates to twisting yarn in general, and in particular to a twisting method and a twisting frame for such a twisting method.

In conventional processes of picking a single yarn and applying a twist to it, or in the conventional process twisting two or more yarns together (a so-called throwing process), cam mechanisms and/or computers are used in order to create irregularities in the yarn. When such a yarn has been processed into woven goods or knit goods, colour density variations appear in the dyeing process which result in the appearance of uneven dyeing. In such a twisting method, ring twisters, two-for-one twisters, Italy twisters, covering machines or false twisters can be used.

Methods using a conventional twisting machine produce a yarn with an irregular feel by varying the twist of the yarn at random. This randomness produces an artificial texture with very little natural feel, and accordingly it is not very comfortable for the wearer.

The German patent publication DE-C-37 147 14 discloses a device for controlling the twisting of three yarns to perform a roving. The three yarns are provided by separate supply means operating at different speeds, the length of each yarn in the twisted roving being different. The twisting onto a spindle is controlled by a predetermined operation program. The slowest running supply means for the shortest yarn to be twisted is taken as the control parameter for determining the length of the yarn.

The object underlying the present invention is to provide a twisting method and a twisting frame capable of producing yarns having a natural feeling of comfort to human beings.

According to the present invention, a twisting method and a twisting frame are provided as defined in claims 1 and 2. Yarn can be manufactured on an industrial scale wherein the twist of the yarn does not vary randomly. Rather, the variations have a distribution in particular a 1/f fluctuation resulting in the effect that the yarn will have a natural feeling of unevenness. In the present application, the expression "1/f fluctuation" is defined and understood as a power spectrum with a frequency component f, and it is proportional to 1/f^k, wherein k is approximately 1.

In such a twisting method, a twist is applied to a single yarn or a plurality of yarns, wherein the twist is applied to the yarn or the yarns by setting the twist count to correspond to the strengths of serial signals having a 1/f fluctuation.

In the twisting frame according to the invention, which twists a single yarn or a plurality of yarns, there are provided a feed roller that draws the yarn or the yarns, and a spindle that receives the yarn or the yarns fed from the feed roller. Then, a twist count having a 1/f fluctuation is applied to the yarn or the yarns by setting the rotational speed of the feed roller or the spindle to correspond to the strengths of serial signals having a 1/f fluctuation.

In an embodiment of the twisting frame, the twist count having a 1/f fluctuation is applied to the yarn or the yarns by setting the rotational speed of both the feed roller and the spindle to correspond to the strengths of serial signals having a 1/f fluctuation.

By means of the twisting method and the twisting frame according to the invention, the twist of the yarn manufactured thereby does not change randomly, rather the change has a specific distribution with a 1/f fluctuation imparting a special feeling of comfort and aesthetic beauty to the wearer.

Accordingly, woven goods or knit goods using such a yarn also have a 1/f fluctuation. It is due to this 1/f fluctuation in the twist that the goods are characterized by a particularly comfortable feel and, subsequent to dyeing, by colour density variations, which again impart a special feeling of comfort and aesthetic beauty to the wearer.

The invention will be explained in more detail below by means of preferred embodiments and with reference to the accompanying drawings, wherein

Fig. 1

shows an overview diagram of the principal components of a twisting frame according to an embodiment; and

Fig. 2

is a block diagram of the drive system for motors used in the twisting frame.

In the method of twisting a yarn or a plurality of yarns, when applying a twist to a yarn 11, changes are imparted having a 1/f fluctuation to the twist resulting in that the twist of the yarn 11 has a 1/f fluctuation. Accordingly, the twist of the yarn 11 will vary with a correlation having a 1/f fluctuation making it possible to manufacture - in large quantities using mechanical equipment - a yarn having a feel similar to yarn spun by hand. Furthermore, spun yarn and/or filaments may be used as a yarn 11.

Twisting Frame

A twisting frame 1 as shown in the embodiment of Fig. 1 is a device to twist yarn by applying a twist to a single yarn or a plurality of yarns 11.

The twisting frame 1 is provided with a plurality of motors, for example a feed motor 21 and a spindle motor 22 each of which can be controlled independently.

In the twisting frame 1 according to Fig. 1, the feed motor 21 is used to drive feed rollers 31. The rotational speed of feed rollers 31 can be determined, for example, by imparting a prescribed rotational speed to the feed roller or feed rollers 31 via belts and/or gears (not shown in detail), and adjusting the size and number of gears. Also, an arbitrary rotational speed can be imparted to a spindle or spindles 41 by rotating a tin roller 32 by means of the spindle motor 22. These motors 21 and 22 can also be used in common, where necessary, and the rotational speed of the rollers 31 and 32 can be adjusted using converters, such as belts and/or gears.

Feed Rollers

The feed roller or the feed rollers 31 have a prescribed rotational speed, and they draw out a single yarn or a plurality of yarns 11 together. The yarn 11 is drawn out by being pinched and rotated by the feed roller or rollers 31. The drawing speed of the yarn 11 is determined by the diameter and the rotational speed of the respective feed roller 31.

Spindles

The rotation of the respective spindle imparts a twist to the yarn 11 fed from the feed roller 31, and subsequently the yarn 11 is wound onto bobbins. In reality, the degree of twist is set for the yarn to be able to withstand downstream processes, generally weaving or knitting and to affect the hand of finished woven fabrics or knitted goods. The degree of twist can be expressed by a twist coefficient as indicated in the following equation (1):$$\text{K =}\frac{\text{T}}{\sqrt{\text{Ne}}}$$ wherein

K =

twist coefficient

T

= twist count and

Ne

= yarn count.

For yarns of the same yarn count, the twist count increases as the twist coefficient increases, forming yarn with a hard hand, and the twist count decreases as the twist coefficient decreases, forming a bulky yarn with soft hand.

In a typical case, the twist coefficient will be 2,5 to 4,5. To obtain yarns of the same hand, but with different yarn counts, the twist coefficient is set to be constant, and the twist count is set to correspond to the yarn count. The twist is determined by the length of the yarn fed from the feed roller 31 and by the number of twists imparted over the length. Therefore, the twist can be modified by keeping either parameter constant and varying the other. To increase the twist at the same yarn count, the feed from the feed roller 31 can be kept constant while increasing the rotation of the spindle 41. On the other hand, the rotation of the spindle 41 can be kept constant while reducing the feed from the feed roller 31. The same result will be achieved in either case.

1/f Fluctuation

The present inventor has discovered that a 1/f fluctuation would impart a particularly comfortable feel to human beings. The results were published in a paper entitled "Bioinformation and 1/f Fluctuation", Applied Physics, 1985, pp. 429 to 435, and in another-paper entitled "Biocontrol and 1/f Fluctuation", Journal of Japan. Soc. of Precision Machinery, Vol. 50, No. 6, 1984, pp. 109-114. The abstract of these papers reads as follows: "The 1/f fluctuation provides a comfortable feeling to human beings; the reason is that the variations in the basic rhythm of the human body have a 1/f spectrum. From another perspective, the human body eventually becomes tired of a constant stimulation from the same source, but conversely, the body feels uncomfortable if the stimulations were to change too suddenly. Therefore, a 1/f fluctuation is a fluctuation of the right proportion between these two extremes."

In addition, an excerpt from "The World of Fluctuations" by Brubachs, published by Kodansha, reads as follows: "For example, the rhythms exhibited by the human body, such as heart beats, hand-clapping to music, impulse-release period of neurons, and alpha rhythms observed in the brain, are all basically 1/f fluctuations, and it has been shown experimentally that if a body is stimulated by a fluctuation like these biorhythmic 1/f fluctuations, it would feel comfortable."

Fluctuations or variations exist in various forms throughout the natural world. The gurgling of a stream, a soft and gentle breeze, and other phenomena that impart a comfortable feeling to human beings have a 1/f fluctuation, whereas typhoons and other strong winds that impart uneasiness do not have a 1/f fluctuation.

Motor Control

Fig. 2 is a block diagram in order to illustrate the motor control. A controller 6 receives signals from a feed motor setter and spindle-motor setter 61, a 1/f-fluctuation signal generator 62 and a twist count setter 63. These signals are processed by the controller 6 which is connected to drivers 64 which control the respective motors, namely the feed motor 21 and the spindle motor 22. Also, the feed motor 21 and the spindle motor 22 are provided with a corresponding speed detector 25 from which feedback signals are supplied to the corresponding drivers 64 allowing the respective rotational speed to be controlled.

The feed motor setter and spindle motor setter 61 set the speed of each motor 21 and 22, respectively, to a prescribed value. By determining a 1/f fluctuation signal from the 1/f fluctuation signal generator 62 based upon these prescribed speed values, a 1/f fluctuation can be imparted to the rotational speed of the respective motors 21 and 22. In addition, when the number of twists of the yarn 11 is set by using the twist count setter 63 of the yarn 11, a yarn 11 having a 1/f fluctuation based on this twist count will be spun.

1/f Fluctuation Signal

The 1/f fluctuation signal is determind from y₁, y₂, y₃, ... formed by calculating n coefficients a₁, a₂, a₃, ... an in a sequence of random numbers x₁, x₂, x₃, ... . Here, y_j can be expressed by equation (2) indicated below. It should be noted that the sequence of numerical values forming y₁, y₂, y₃, ... has a 1/f spectrum. For further details, reference is made to Seitai shingô (Biological Signaling), chapter 10, "Biological Rhythms and Fluctuations", published by Corona Publishers, Ltd..

1/f Fluctuation Signal Generator

The 1/f fluctuation signal generator 62 shown in Fig. 2 operates as follows. In a first step, a sequence-of random numbers is generated using, for example, a computer. In a second step, this sequence of random numbers is stored in a storage device, wherein a certain number n of coefficients a is successively calculated, and then a sequence of numerical values y is obtained by a linear transformation.

This numerical sequence has a 1/f spectrum; hence it is converted into an electrical signal as a 1/f fluctuation signal and output as a motor control signal. For example, large values in the numerical sequence can be set to correspond to a high electric potential to increase the speed of the respective motor, thereby creating a larger number of twists. Other methods can also be employed, such as a numerical control to control the rotational frequency of the respective motors using values from the numerical sequence. If the inertia of the motors and other components of the control system of the twisting frame 1 is large, the twist can also be applied by reducing the level of the 1/f fluctuation control signal, as necessary.

Twist Control

As a method of imparting a 1/f fluctuation to the yarn 11, the twist can be made to vary by setting the rotation of the spindle 41 to be constant and controlling the feed motor 21 which drives the respective speed roller 31. For example, if a 1/f fluctuation is imparted to the speed at which the yarn 11 is taken up by the feed roller 31, the twist of the yarn 11 will vary between tight and loose, and this variation will have the characteristics of 1/f fluctuation. The take-up speed of this feed roller 31 can be adjusted by controlling the rotational speed of the feed motor 21. Therefore, by applying a 1/f fluctuation signal to the rotational speed of the feed motor 21 and using the rotation of the spindle 41 to change the twist of the yarn 11, a 1/f fluctuation is applied to the twist of the yarn 11.

On the other hand, a twist varying with a 1/f fluctuation can also be applied to the yarn 11 by keeping the rotation of the feed motor 21 and therefore the rotation of the feed roller 31 constant and applying a 1/f fluctuation signal to the rotational control of the spindle motor 22 which in turn drives the tin roller 32 and therefore controls the rotation of the spindles 41. In another embodiment of the invention, it is also possible to apply a 1/f fluctuation signal to both the feed motor 21 and the spindle motor 22 so that both of the motors are controlled by a 1/f fluctuation signal concurrently.