JPS6375120A - Production of carbon fiber - Google Patents

Abstract

PURPOSE:To efficiently control taking out tension of yarn with a simple appara tus, by providing a electromagnetic brake to each axis for mounting a bobbin, making up a number of electromagnetic brakes as one set, connecting the brakes to common controllers for each set and, controlling exciting currents. CONSTITUTION:An electromagnetic brake is provided to each axis for mounting a bobbin, when fiber bundles of a organic polymer are taken out from a number of bobbins, paralleled and sent out to the following process. Then, at least 50 electromagnetic brakes are made up as one set and one controller is provided for each set to regulate the exciting current of each electromagnetic brake. Thereby, taking out tension of yarn from plural bobbins is collectively con trolled.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an excellent fluff-free carbon fiber that can be used in a tension control method when sending a large number of organic polymer fiber bundles, which are raw materials for carbon fiber, to a firing process. The present invention relates to a method for producing carbon fiber that can be produced continuously and stably on an industrial scale.

(Prior Art) It is already well known to produce carbon fibers by firing polyacrylonitrile-based, cellulose-based, or pitch-based organic polymer fiber bundles. Since the production rate of the carbon fiber firing process is much slower than that of the organic polymer fiber bundle manufacturing process, the fiber bundle is usually wound in a fixed amount onto a bobbin, and the bobbin is attached to a creel during the firing process. ,
A method of manufacturing carbon fiber by continuously unwinding and firing is used.

(Problems to be Solved by the Invention) On an industrial scale, the number of bobbins is several hundred, and these fiber bundles must be unwound with appropriate tension. If the tension is too strong, the fiber bundles will get stuck in the bobbin, causing fluff. Even if fluff occurs in one fiber bundle, thread breakage will occur during the firing process, and this will cause the reaction to run out of control. This will result in a situation where the operation will have to be stopped.

In addition, if the tension is too weak, the fiber bundles may sag, get entangled with fiber bundles from other adjacent bobbins, causing fluff, or the tension during the firing process may fluctuate, resulting in a decrease in the mechanical properties of the carbon fibers. A problem arises.

In addition, as a method of controlling the unwinding tension of the bobbin, conventional methods have been used to attach a band brake to the bobbin shaft and use the force of a weight or a spring, but as the winding diameter of the bobbin decreases, Since the tension changes, it is necessary to manually change the number of weights or change the force of the spring. In particular, as the amount of winding of the bobbin is increased in order to improve productivity, the unwinding tension fluctuates more, so the tension must be adjusted more frequently. As mentioned above, the number of bobbins supplied to the firing process is in the hundreds, so
In reality, it was nearly impossible to manually adjust these one by one.

As a way to overcome this drawback, the conventional method was to
As shown in Japanese Patent No. 6982, a method has also been proposed in which a displacement detection roller is provided for each bobbin and the tension of a band brake is controlled according to the amount of displacement of the roller to keep the unwinding tension constant. This method also requires as many detection rollers as there are bobbins, making the equipment complicated and difficult to implement on an industrial scale.

Normally, the number of filaments in organic polymer fiber bundles used in the production of carbon fibers ranges from 1,000 to 15,000 filaments, so it is necessary to be able to change the unwinding tension by at least 15 times. Since the range of unwinding tension that can be adjusted with brakes is narrow, it is not possible to control the tension to an appropriate level, which causes problems such as frequent troubles during the firing process.

In order to solve the above-mentioned conventional problems, the present invention makes it possible to efficiently control the unwinding tension with simple equipment without requiring any human effort even when unwinding a large number of bobbins with a large winding amount. The present invention aims to provide a method for producing carbon fiber.

(Means and effects for solving the problem) Therefore, the present invention provides a method for producing carbon fibers by sending a large number of organic polymer fiber bundle bobbins to a firing process while continuously unwinding each bobbin. An electromagnetic brake is provided on the shaft, each set of 50 electromagnetic brakes is connected to one controller, and the excitation current of the electromagnetic brake is adjusted by the controller. This system allows the organic polymer fiber bundle to be sent to the firing process while controlling the unwinding tension of multiple bobbins all at once.
This is a means to solve problems.

This will be explained in more detail below.

FIG. 1 shows an example of an apparatus for carrying out the present invention.
A large number of organic polymer fiber bundle bobbins 2 are attached to a creel 1, and each fiber bundle is unwound by a take-up roll 3 via a guide bar or guide roll 4 and sent to a firing process.

FIG. 2 is a view of the creel shown in FIG. 1 viewed from the direction A, and an electromagnetic brake 6 is directly connected to one end of each bobbin mounting shaft 5. Since the bobbin mounting shaft is rotatably supported by the rolling bearing 7, the bobbin can be unwound with a slight unwinding tension when the electromagnetic brake is not operated. Although it is necessary that the fiber bundle bobbin and the bobbin mounting shaft rotate together, a simple fixing method such as fitting an elastic ring such as a leaf spring or an O-ring onto the bobbin mounting shaft is sufficient.

Further, as shown in Fig. 3, the electromagnetic brake 6 is connected to a controller 7, and by changing the excitation current of the electromagnetic brakes with the controller, the torque of all the electromagnetic brakes connected to the controller can be simultaneously controlled. Can be adjusted to the same torque. Normally, fiber bundle bobbins with the same winding volume are used to manufacture carbon fiber, so the winding diameter change during production is the same for each bobbin, and as mentioned above, one controller can change multiple electromagnetic brakes. There is no difference in tension between the bobbins. Number of electromagnetic brakes that can be controlled by one controller: Yes (any number is fine, but if the number is too large, the capacity of the controller becomes extremely large and is not economical, so 500 or less is preferable.

In the embodiment shown in Fig. 3, the unwinding tension is adjusted manually, but the firing speed is only a few m/min at most, and the change in the bobbin winding diameter is slow, so the excitation current is adjusted only once a day. You can do this once every few hours or once every few hours, but if there are many controllers, the work will be complicated, so one controller will require at least 50
It is necessary to control more than one electromagnetic brake.

By doing this, at most 10 or less controllers can be combined into one
Since the operation only needs to be performed once or several times a day, the unwinding tension of the bobbin can be easily controlled to an appropriate value without any manual effort.

FIG. 4 shows another embodiment in which an arithmetic unit 8 is connected to the controller 7. In this way, the excitation current can be automatically adjusted by determining the relationship between the winding diameter and the required voltage and the relationship between the firing speed and the change in the winding diameter, without requiring any manual intervention. , is more preferable because the unwinding tension of all bobbins can be kept constant.

The electromagnetic brake 6 used in the present invention can be of any type, such as an electromagnet or an electromagnetic powder, as long as it can electrically vary the torque. The present inventors investigated various changes in the number of filaments, the amount of winding, the type of organic polymer, etc. of the fiber bundle, and found that the appropriate unwinding tension should be in the range of 25 to 50 cm per denier. confirmed. Therefore, except in special cases, the torque of the electromagnetic brake can be as small as about 10 kg-cm, making it extremely compact and easy to use. Also, tension can be controlled accurately and easily even on fiber bundle bobbins with large winding diameters. can be done.

(Example) Single fiber denier 1.3 d and number of filaments 12,000 wound into a paper tube with an outer diameter of 100 mm and a winding diameter of 420 mm.
Polyacrylonitrile polymer fiber bundle bobbin consisting of book 3
00 pieces were attached to the creel 1 shown in Figs. 1 and 2, and the speed of the take-up roll 3 was set to 3.2 m/min, and the carbon fibers were continuously unwound and fired to produce carbon fibers. . The electromagnetic brake used was a commercially available one with a rated current of 0.4 A, a rated torque of 10 kg, and a power supply voltage of 24 V. The controller consisted of a transformer, a slider, and a rectifier, and one controller could handle 300 bobbins. were controlled all at once. The slider was operated manually every 10 hours so that the unwinding tension was approximately 32 cm/denier, and the total excitation current flowing to the 300 electromagnetic brakes was adjusted as shown in Figure 5. Figure 6 shows Electromagnetic brake - shows the relationship between the excitation current and brake torque per piece.The results of measuring the unwinding tension on 20 randomly selected bobbins immediately before and after adjusting the excitation current of the electromagnetic brake are shown. As shown in Table 1, the total unwinding tension during operation is ゛25~50■
/denier, almost no fluff was observed, and the operation could be completed without any trouble. Moreover, the obtained carbon fiber was free of fuzz and was of good quality.

Table 1 (Effects of the Invention) As explained in detail above, by using the present invention, it is possible not only to stably produce carbon fiber on an industrial scale, but also to obtain high-quality carbon fiber with little fuzz. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a view taken along arrow A in FIG. 1, FIGS. 3 and 4 are wiring system diagrams of the present invention, and FIG. FIG. 6 is a diagram showing the change in the total excitation current with the passage of operating time in the present invention, and FIG. 6 is a diagram showing the relationship between the excitation current and brake torque of the electromagnetic brake used in the present invention. Explanation of the main parts of the diagram 2... - Organic polymer fiber bundle bobbin 6 - Electromagnetic brake 7 - Controller Patent applicant Mitsubishi Rayon Co., Ltd. Figure 1 Figure 2 Figure 5 Operating time (Hr)

Claims (2)

[Claims] (1) In a method of manufacturing carbon fiber by continuously unwinding a large number of organic polymer fiber bundle bobbins and sending them to a firing process, each bobbin mounting shaft is provided with an electromagnetic brake, and at least 50 of the electromagnetic brakes are connected to each bobbin. By connecting each set as a set to one controller, and adjusting the excitation current of the electromagnetic brake by the controller, the unwinding tension of multiple bobbins can be controlled at once and the organic polymer fiber bundle can be processed. A method for producing carbon fiber, characterized by sending the carbon fiber to a firing process. (2) The method for manufacturing carbon fiber according to claim 1, wherein the excitation current adjustment of the electromagnetic brake is automatically performed by a computing unit.