WO2004016841A1

WO2004016841A1 - Manufacturing process of drawn anti-felting worsted yarn, drawn anti-felting worsted yarn and low speed drawing machine

Info

Publication number: WO2004016841A1
Application number: PCT/KR2002/001293
Authority: WO
Inventors: Ok-Kyo Seo; Seung-Jin Kim; Soo-Hyun Park; Dae-Hoon Lee
Original assignee: Ok-Kyo Seo; Seung-Jin Kim; Soo-Hyun Park; Dae-Hoon Lee
Priority date: 2002-07-09
Filing date: 2002-07-09
Publication date: 2004-02-26
Also published as: KR20050021449A; CN1630745A; KR100740012B1; AU2002318490A1; CN1308517C

Abstract

Disclosed herein is a method for manufacturing a fine count non-shrinkable worsted yarn which comprises the steps of loading a worsted yarn in a hank form, spraying a reducing agent, temperature-elevating, low-speed drawing, relaxing, setting, and suddenly cooling and cleaning. Further disclosed are a non-shrinkable drawn worsted yarn manufactured by the method and a low-speed drawing machine for implementing the method.

Description

MANUFACTURING PROCESS OF DRAWN ANTI-FELTING WORSTED YARN, DRAWN ANTI-FELTING WORSTED YARN AND LOW SPEED DRAWING MACHINE.

Technical Field

The present invention relates to a method for manufacturing a non- shrinkable drawn worsted yarn, a non-shrinkable drawn worsted yarn manufactured by the method, and a drawing machine for implementing the method. More particularly, the present invention relates to a method for artificially making a worsted yarn into filaments and imparting shrink resistance to the drawn worsted yarn by low-speed drawing a worsted yarn in a hank form, followed by setting, a non-shrinkable drawn worsted yarn manufactured by the method, and a low-speed drawing machine for effectively implementing the method.

Background Art

Since wool fibers have excellent flexibility, spinning performance, heat insulation capacity, moisture absorption capacity, etc., they have been recognized as the highest quality fiber materials. However, they are limited in the applications to wool products due to the following problems which do not correspond to the needs of consumers.

First, since wool fibers have scales on their surface, they are likely to shrink due to a felting phenomenon upon washing. For this reason, the wool fibers generally have poor water washability and therefore must be subjected to dry- cleaning.

A great deal of research and development for preventing the wool fibers from shrinking has been made. For example, scales formed on the surface are chemically treated to remove and coat them. Indeed, it is known that this shrink resistance treatment is excellent in terms of shrink resistant effects.

However, many methods developed hitherto including chemical treatment have their respective problems.

For example, there is a method comprising chlorinating a wool fiber in a top state to remove scales and coating the chlorinated wool fiber with a polymer. This method is excellent in terms of shrink resistant effects, but the wool top thus treated has poor workability upon spinning and contaminates the spinning machine. Further, the absorption rate of a dye is too high to obtain uniform dyeing. In the case that top dyeing is carried out to prevent the non-uniform dyeing, the need for small lot production cannot be satisfied, and further there are many manufacturing problems. Accordingly, special management is required for the method.

On the other hand, since wool products are made of sheep wool as a natural raw material, there is no step for controlling the denier of a wool fiber, unlike synthetic fibers. Accordingly, the denier and quality of a wool fiber are determined by the variety, habitat and regimen of sheep. For these reasons, relatively thin and high-quality raw wool used to manufacture fine count wool products is very expensive, resulting in the increase in the manufacturing costs of fine count wool products.

Accordingly, it is expected that development of a method for thinning the size of a fiber during a spinning process at low cost can greatly contribute to the reduction in the manufacturing costs of fine count wool products.

However, industrial studies on methods for drawing natural or synthetic fibers in a spun yarn form are not being actively undertaken. Thus, some researchers including the present inventors have conducted intensive research to develop methods for drawing spun yarns, and as a result, introduced methods for drawing synthetic fibers, e.g., nylons and acryl-based spun yarns and natural fiber yarns, e.g., wool yarns.

For example, methods for manufacturing fine count yarns by quickly drawing acrylic spun yarns near a softening temperature to 2~3 times its original length are disclosed in Korean Patent Publication Nos. 1983-2699, 1987-1050 and 2002-329487. However, since these methods are limited to synthetic fiber yarns such as acrylic spun yarns, they are unsuitable for the application to natural fiber yarns such as wool yarns.

On the other hand, as a trial to improve physical properties of a natural fiber such as wool by drawing the fiber, Korean Patent Publication No. 1987-1340 discloses a method for processing wool which comprises loading a worsted yarn or wool blended yarn in a hank form on a pair of drawing rollers placed inside a pressure-resistant tank, drawing the yarn to a critical drawing point while maintaining an optimum drawing temperature, shrinking the drawn yarn to an original length under no tension, and wet-relaxing. At this time, since some scales of the wool fiber are destroyed by drawing, the wool yam exhibits shrink resistance. In addition, the shrinkage and wet relaxation impart a bulky feeling to the wool yam. However, since the worsted yarn is quickly drawn, the worsted yam shrinks due to the restoring force after drawing and therefore a fine count wool yarn cannot be manufactured. Further, the shrink resistant effects of the wool yam thus manufactured are insufficient.

On the other hand, a heat drawing machine for implementing the drawing methods discussed above is disclosed in Korean Patent Publication No. 1987-1049 and an improved drawing machine thereof is disclosed in Korean Patent Publication No. 2002-327824, which was filed by the present inventors. According to the latter publication, the drawing machine comprises a pressure-resistant tank compartment for providing drawing conditions such as tensile force, temperature and pressure to a spun yam and a feed cylinder compartment for providing feed force/operation force to the pressure-resistant tank compartment.

Using the feed cylinder compartment including a hydraulic cylinder, a hydraulic pipe and a compressor, quick drawing of an acrylic spun yam can be performed without any problem. However, since a means for controlling the hydraulic pressure between the hydraulic cylinder and the compressor is not provided, the compressive force generated from the compressor can be provided to the hydraulic cylinder at one time and thus low-speed drawing for manufacturing a drawn wool yarn having excellent shrink resistant effects cannot be realized. In a relaxing step and subsequent steps for maintaining the state after drawing, a hydraulic oil inside the hydraulic cylinder may flow backward to the compressor due to the restoring force of the wool fiber, resulting in hydraulic pressure loss. Accordingly, there is a problem that the relaxing step, which is an indispensable step for performing the low-speed drawing method of the present invention, is incompletely carried out.

Disclosure of the Invention

Therefore, the present invention has been made in view of the above problems of prior arts for drawing wool fibers, and it is an object of the present invention to provide a method for manufacturing a fine count non-shrinkable worsted yam from a medium count or coarse medium worsted yam without any shrinkage due to a felting phenomenon, which is the largest problem of wool products. It is another object of the present invention to provide a non-shrinkable drawn worsted yam manufactured by the above method.

It is another object of the present invention to provide a drawing machine for implementing the above method. In order to accomplish the above objects of the present invention, there is provided a method for manufacturing a non-shrinkable drawn worsted yam, comprising the steps of: loading a worsted yarn in a hank form on a pair of drawing rollers placed inside a pressure-resistant tank and closing the pressure-resistant tank; spraying a reducing agent on the worsted yam; supplying steam to the pressure-resistant tank and raising the internal temperature of the pressure-resistant tank to a drawing temperature; low-speed drawing the worsted yam for 30~300 seconds to 1.3~2 times its original length; relaxing the tension of the worsted yam; setting the relaxed worsted yam; and adding clean water or a mixture of an oxidant and clean water to the set worsted yam to suddenly cool, neutralize and clean it.

In the method for manufacturing a non-shrinkable drawn worsted yam of the present invention, as the worsted yam loaded on a pair of drawing rollers, a hard twisted yam is used. Since the hard twisted yarn has strong binding and frictional force between fibers, slip can be prevented during drawing and a high drawing rate can be obtained.

In a preferred embodiment according to the method for manufacturing a non-shrinkable drawn worsted yam of the present invention, pre-evacuation is preferably carried out to previously reduce the internal pressure of the pressure- resistant tank prior to supplying steam to the pressure-resistant tank. The pre- evacuation can prevent the over-pressure of the pressure-resistant tank when the tank is heated to 100 ^°C or higher by steaming. In the method for manufacturing a non-shrinkable drawn worsted yam of the present invention, the worsted yarn in a hank form may be immersed in a reducing agent solution instead of spraying a reducing agent, prior to loading on the roller.

According to the present invention, there is provided a non-shrinkable drawn worsted yam manufactured by the above method. The non-shrinkable drawn worsted yarn has more counts than prior to drawing, and no or few shrinkage problems due to a felting phenomenon upon washing.

According to the present invention, there is provided a drawing machine for low-speed drawing a worsted yarn, comprising: a pressure-resistant tank compartment including a pressure-resistant tank, a steam feed pipe for feeding steam into the pressure-resistant tank, a steam discharge pipe for discharging steam from • the pressure-resistant tank, a cooling water spray nozzle, a pair of rotary rollers and an opening door for supplying a raw yarn to the pressure-resistant tank; and a feed cylinder compartment for providing a feed force to the pressure-resistant tank compartment including a compressor, a hydraulic cylinder and a hydraulic pipe wherein the hydraulic pipe of the feed cylinder compartment includes a flow rate control valve for controlling the hydraulic pressure provided to the hydraulic cylinder and a bidirectional check valve for preventing the backflow of hydraulic pressure, thereby controlling the drawing speed of the raw yam and stably controlling relaxing of the yam and maintaining the state.

Brief Description the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a side cross-sectional view showing the overall structure of a machine for low-speed drawing a worsted yarn according to one embodiment of the present invention; and Fig. 2 is a side cross-sectional view showing the operation of the machine for low-speed drawing a worsted yam of Fig. 1.

Best Mode for Carrying Out the Invention

Manufacture of non-shrinkable drawn worsted yarn

Hereinafter, a method for manufacturing a non-shrinkable drawn worsted yarn according to the present invention will be explained in more detail based on the respective steps.

Preparation of raw yarn First, a worsted yarn used in the method of the present invention as a raw material is explained.

The worsted yarn used in the present invention includes pure wool and wool-blended yams, but is not limited thereto. In particular, using the method of the present invention, a high quality fine count worsted yam can be manufactured from an inexpensive medium or coarse worsted yarn, which is economically advantageous.

Since spinning of the worsted yam used in the present invention can be carried out by a worsted yarn spinning process known in the art and a commercially available worsted yam can be used in the present invention, details concerning the spinning of the worsted yarn are omitted.

The use of a less twisted yarn as the worsted yam drawn in accordance with the method of the present invention is not preferred since slip may occur during drawing, which makes drawing impossible, due to poor binding and frictional force between fibers. Accordingly, the worsted yarn usable in the present invention is preferably a hard twisted yarn which is hard-twisted by 10-50% compared to typical worsted yarns. A commercially available hard twisted yarn can be used as it is or after further twisting.

Since excessive twisting of a yam may weaken the tenacity of the yarn, appropriate twisting is determined considering drawing rate and twist number of a product to be manufactured.

After a commercially available raw yam is further twisted, steam-setting is carried out at 85 ^°C to fix the twisted yarn.

If the steam-setting is not carried out after twisting, the state is unstable and thus the yam is not formed into a hank. In addition, the yam is likely to shrink by 15-30%.

Loading

The wool yam is wound in the form of a hank having a predetermined size, and loaded on a pair of drawing rollers placed horizontally inside a pressure- resistant tank. The raw yam wound in a hank form may be immersed in a reducing agent solution and then loaded on the rollers. Reducing agent spraying

After the raw yam is loaded in the pressure-resistant tank, a reducing agent is sprayed thereon. As the reducing agent, an aqueous solution of sodium bisulfite or acidic sulfite soda is preferably used. Since the treatment with the reducing agent cleaves the cystine bonds of keratin to form thiol groups, the state modified by drawing is easily fixed and thus drawing and shrink resistance can be improved.

Temperature elevation After swelling is completed, steam is supplied to the pressure-resistant tank to raise the intemal temperature of the pressure-resistant tank to 100-150 ^°C, which is the optimum drawing temperature range.

At this step, pre-evacuation is preferably carried out to previously reduce the internal pressure of the pressure-resistant tank to 60~80%> prior to supplying steam to the pressure-resistant tank. Since the pre-evacuation can prevent the overpressure of the pressure-resistant tank, the tank is easily heated by steaming.

If steam is supplied to the pressure-resistant tank to raise the temperature to 100°C without pre-evacuation, the pressure of the pressure-resistant tank is increased to 2kg/cm² or higher, which makes the temperature elevation difficult. In addition, there is a problem in that a tank capable of resisting high pressure must be used. Since the intemal pressure of the pressure-resistant tank is just lkg/cm² at 100°C in a state where the degree of the pre-evacuation is 60%, it is preferred in terms of safety.

Accordingly, it is preferred that pre-evacuation is carried out to previously reduce the intemal pressure of the pressure-resistant tank prior to supplying steam to the pressure-resistant tank, and then the internal temperature is raised to the optimum drawing temperature.

Low-speed drawing

While maintaining the optimum drawing temperature, the rollers are rotated at a low-speed so as to uniformly draw the wool yam.

At this step, it is very important to carry out the drawing at a low speed for a drawing time of 30-300 seconds. If the wool yam is quickly drawn, tenacity is reduced and cutoffs are generated due to slipping, which makes drawing difficult. Further, since the wool yam may shrink after drawing, a fine count drawn worsted yam intended in the present invention cannot be manufactured.

Relaxing

Following drawing, the worsted yam is relaxed by 0-30% for a predetermined time to relax the tension imparted during drawing. Setting After relaxing, the drawn worsted yam is set at a temperature of 80-120 ^°C to fix the worsted yam into a drawn state. If the setting is not carried out, the worsted yarn shrinks by about 15-30%). The set wool yam does not shrink upon washing.

Sudden cooling and cleaning Following the setting step, a solution containing an oxidant such as hydrogen peroxide or sodium perborate or cleaning water at 5-10^°C is sprayed on the worsted yarn to suddenly cool the worsted yarn, neutralize the reducing agent and remove various contaminants remaining on the fiber. If the sudden cooling is not carried out, the worsted yam is shrunk by about 5—10% and thus a desired drawing rate cannot be attained.

The neutralization with the oxidant solution removes the reducing agent remaining on the fiber and thus dimension stability and shrink resistance can be effectively improved. Following neutralization and cleaning with the oxidant solution, cleaning water is preferably sprayed on the worsted yarn to remove residual oxidant.

Low-speed drawing machine

Hereinafter, the low-speed drawing machine according to the present invention is explained in more detail with reference to the accompanying drawings.

Fig. 1 is a side cross-sectional view showing the overall structure of the machine for low-speed drawing a worsted yarn according to one embodiment of the present invention. As shown in Fig. 1, the low-speed drawing machine comprises a pressure-resistant tank compartment 10 for providing drawing conditions such as tensile force, temperature and pressure to a worsted yarn to be drawn and a feed cylinder compartment 20 for providing feed force/operation force to the pressure- resistant tank compartment 10.

The pressure-resistant tank compartment 10 includes a tank 11 capable of resisting high pressure, an opening door 12 and a conveying rail 12a installed at one side of the tank compartment 10, a carriage 13 equipped with rotary rollers 13a for providing tensile force to the worsted yam, and a movable rail 13b for moving the carriage 13 backward and drawing the worsted yarn.

Cooling water spray nozzles 14a are installed on the upper or side part of the carriage 13 to cool the drawn yam. Cleaning water, reducing agent, oxidant, etc., can be sprayed through the spray nozzles 14a.

In the embodiment of the present invention, a feed pipe 14b of a pump 14 communicating with the spray nozzles 14a is connected to a cleaning water storage tank 14c and a mixing tank 14d. A check valve 14e for controlling oil flow is installed on the feed pipe 14b. Chemical substances such as a reducing agent or cleaning water are selectively supplied to the pressure-resistant tank through the feed pipe 14b. On the other hand, in order to provide appropriate drawing conditions such as drawing temperature and pressure to the pressure-resistant tank 11, a steam feed pipe 15a for supplying high temperature steam to the pressure-resistant tank 11 and a steam discharge pipe 15b for exhausting the supplied steam are installed on the lower and upper parts of the pressure-resistant tank 11, respectively. A vacuum pump 16 connected to a suction pipe 16a evacuates the pressure-resistant tank 11 and facilitates the supply of steam through the steam feed pipe 15 a.

The feed cylinder compartment 20 connected to the opening door 12 of the pressure-resistant tank compartment 10 provides feed/operation force to the pressure-resistant tank compartment 10. The feed cylinder compartment 20 includes a compressor 21 for generating a compressive force, a hydraulic cylinder 23 for providing the feed/operation force through the compressive force generated from the compressor to the carriage 13 and the opening door 12 of the pressure-resistant tank compartment 10, a hydraulic pipe 22 for connecting the compressor 21 and the hydraulic cylinder 23, a flow rate control valve 24 and a bidirectional check valve 25 being installed on the hydraulic pipe 22.

In particular, the low-speed drawing machine of the present invention further comprises the flow rate control valve for slowly providing a constant flow rate to the hydraulic cylinder 23 through the compressor 21 and the bidirectional check valve 25 for preventing the hydraulic loss due to the backflow of a hydraulic oil supplied to the hydraulic cylinder 23 toward the compressor 21. The flow rate control valve 24 and the bidirectional check valve 25 are installed on the hydraulic pipe 22.

The flow rate control valve 24 and the bidirectional check valve 25 include mechanical/electronic type valves known in the art. Considering the weight of the carriage and opening door and tensile force provided to the worsted yarn for drawing, it is possible for a person skilled in the art to make various modifications including altering total number/capacity of the valves. It is to be understood that all these modifications belong to the scope of the present invention.

On the other hand, Fig. 2 is a side cross-sectional view showing the operation of the machine for low-speed drawing a worsted yam according to the present invention. The operation of the low-speed drawing machine according to the present invention will be specifically explained in more detail with reference to Fig. 2.

The hydraulic cylinder 23 is moved backwards to open the opening door 12 and load a worsted yarn in the form of a hank on the rollers 13a placed inside the pressure-resistant tank 11. The forward movement of the hydraulic cylinder 23 closes the door 12.

After the pressure-resistant tank 11 is closed, a reducing agent contained in the mixing tank 14d is sprayed through the spray nozzles 14d. Next, the vacuum pump 16 is operated to evacuate the pressure-resistant tank 11 so as to easily introduce steam into the pressure-resistant tank 11. At this time, the degree of vacuum in the pressure-resistant tank 11 is preferably 60~80%>. High temperature steam is fed into the evacuated pressure-resistant tank 11 through the steam feed pipe 15a to raise the intemal temperature of the pressure-resistant tank 11 to the optimum temperature required for drawing the yam.

After raising the intemal temperature of the pressure-resistant tank 11 to the optimum temperature required for drawing the yam, the compressor 21 is operated to feed a hydraulic oil to the hydraulic cylinder 23. At this time, the flow rate control valve 24 slowly provides a constant flow rate of the hydraulic oil to the hydraulic cylinder 23 to draw the yam.

When the drawn yam is left for a long period of time, the hydraulic oil in the hydraulic cylinder flows backward to the compressor 21 due to the restoring force of the yarn, and as a result, the drawn yam shrinks. For this reason, in the low-speed drawing machine of the present, after the drawing is completed, the compressor 21 is stopped and subsequently the bidirectional check valve 24 is closed to prevent the backward flow of the hydraulic oil supplied to the hydraulic cylinder 23 and reduce the hydraulic loss due to the restoring force of the yam.

Then, relaxation is carried out for a predetermined time to remove the restoring force of the yam. At this time, the bidirectional check valve 25 is opened and the compressor 21 is reciprocally operated to move the hydraulic cylinder 23 backward.

Steam is further supplied to the relaxed yam to set it, and then exhausted through the steam discharge pipe 15b. Since the supply and exhaust of steam are as discussed above, details are omitted. After setting, the oxidant contained in the mixing tank 14d is sprayed through the spray nozzles 14a installed on the upper part of the pressure-resistant tank 11 to cool the drawn yam and neutralize and remove residual reducing agent. Then, cleaning water is further sprayed to wash the remaining oxidant. Finally, the drawn yam is taken out from the opening door 12. Hereinafter, the method for manufacturing a fine count non-shrinkable worsted yarn according to the present invention will be described in more detail with reference to the following examples.

Example 1 A wool fiber having a denier of 21.7μm was spun to produce a l/40TStm worsted yarn of 100% wool. After the worsted yam was double-twisted, it was twisted with S950 TPM and subjected to vacuum-setting at 98 ^°C .

The set worsted yam was reeled in the form of a hank having a size of

12cm, and then loaded on a pair of drawing rollers placed horizontally inside a pressure-resistant tank. After the pressure-resistant tank was closed, 2.0g/l aqueous sodium bisulfite solution was sufficiently sprayed on the worsted yam while rolling for 5 minutes.

Thereafter, after the pressure-resistant tank was evacuated to 70%, steam was supplied to the pressure-resistant tank to raise the intemal temperature to 110 ^°C . The temperature was maintained for 10 minutes to uniformly maintain the wool yam. The worsted yam was slowly drawn for 30-300 seconds to 1.7 times its original length, and relaxed by 15%.

The relaxed drawn yarn was set at 98 ^°C for 30 minutes. The steam was exhausted through a collection pipe. By spraying a 0.5g/l aqueous hydrogen peroxide solution on the drawn worsted yarn for sudden cooling, the remaining sodium bisulfite and impurities were sufficiently neutralized and cleaned. Clean water was further sprayed on the drawn yam to remove remaining hydrogen peroxide.

After the drawn worsted yam in a hank form was taken out, it was hot-air dried and unwound. The denier of the drawn worsted yam was 20μm. The twist number of the yam was shown to be 2/60Nm, which demonstrates that a fine count drawn worsted yam was manufactured.

Examples 2~3 Two wool fibers having a denier of 20.5μm were spun to produce the respective 1/60 Nm worsted yams. After the worsted yams were double-twisted, they were twisted with SI 20 TPM. Subsequently, low-speed drawing of the worsted yarns was carried out in the same manner as in Example 1. At this time, the drawing rate of the worsted yarns was 135% (Example 2) and 150% (Example 3), and relaxing was carried out by 0%> (Example 2) and 5% (Example 3).

The physical properties of the drawn worsted yarns were measured. The results are summarized in Table 1 below.

Table 1

Example 4

A sweater was knitted using the drawn worsted yarn manufactured in Example 3. After the sweater was mechanically washed in accordance with the standard method described in KS K 0432, the change in the size of the sweater was measured. The results are shown in Table 2 below.

Table 2

As shown in Table 2, the sizes of the sweaters were changed within 3%>. Accordingly, the fine count non-shrinkable worsted yam manufactured in accordance with the method of the present invention was water- washable.

Example 5 The drawn worsted yarn manufactured in Example 2 was woven to produce a plain-woven woolen fabric having a waφ and weft density of 64*62, a weight of 6.4oz/yd and a width of 65 inches. The woolen fabric was processed to manufacture a wrap in accordance with the following dyeing processes. (Processing steps) Presetting -> Scouring -> Drying -> Piece Dyeing -> Drying -> Dry processing -> Sponging -> Open blowing

After the wrap thus manufactured was subjected to mechanical washing at 105°F for 8 minutes, change in the size of the wrap was measured.

As a result, the size of the wrap was changed by -0.2% and -0.4% in the warp and weft directions, respectively. That is, little change was observed. In conclusion, the woolen fabric woven using the drawn worsted yam of the present invention exhibited excellent shrink resistant effects.

Industrial Applicability

As apparent from the above description, according to the drawing method and machine of the present invention, a fine count non-shrinkable worsted yam can be manufactured by weaving a medium count or coarse medium worsted yarn or wool-blended yarn from a low-grade wool raw material, low-speed drawing the woven yarn and setting the drawn yam. Therefore, the present invention can greatly reduce costs required for manufacturing fine count non-shrinkable worsted yams. In addition, since non-shrinkable and washable wool products can be produced by the drawing method and machine, the present invention greatly contributes to the utilization of wool products. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

Claims:

1. A method for manufacturing a non-shrinkable drawn worsted yarn, comprising the steps of: loading a worsted yam in a hank form on a pair of drawing rollers placed inside a pressure-resistant tank and closing the pressure-resistant tank; spraying a reducing agent on the worsted yam; supplying steam to the pressure-resistant tank and raising the intemal temperature of the pressure-resistant tank to a drawing temperature; low-speed drawing the worsted yarn for 30-300 seconds to 1.3-2 times its original length; relaxing the tension of the worsted yam; setting the relaxed worsted yarn; and adding clean water or a mixture of an oxidant and clean water to the set worsted yarn to suddenly cool, neutralize and clean it.

2. The method for manufacturing a non-shrinkable drawn worsted yam according to claim 1, wherein the worsted yam loaded on a pair of drawing rollers is a hard twisted yam.

3. The method for manufacturing a non-shrinkable drawn worsted yam according to claim 1, wherein the pressure-resistant tank is evacuated, prior to supplying steam to the pressure-resistant tank.

4. The method for manufacturing a non-shrinkable drawn worsted yam according to any one of claims 1 to 3, wherein the worsted yam in a hank form is immersed in a reducing agent solution instead of spraying a reducing agent, prior to loading on the roller.

5. A non-shrinkable drawn worsted yam manufactured by the method according to any one of claims 1 to 4.

6. A drawing machine for low-speed drawing a worsted yam, comprising: a pressure-resistant tank compartment including a pressure-resistant tank, a steam feed pipe for feeding steam into the pressure-resistant tank, a steam discharge pipe for discharging steam from the pressure-resistant tank, a cooling water spray nozzle, a pair of rotary rollers and an opening door for supplying a raw yarn to the pressure-resistant tank; and a feed cylinder compartment for providing a feed force to the pressure- resistant tank compartment including a compressor, a hydraulic cylinder and a hydraulic pipe, wherein the hydraulic pipe of the feed cylinder compartment includes a flow rate control valve for controlling the hydraulic pressure provided to the hydraulic cylinder and a bidirectional check valve for preventing the backflow of hydraulic pressure.