JPS5831898Y2 - Continuous graphitization equipment for carbon fiber - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an apparatus for continuous graphitization of carbon fibers.

Graphite fibers are produced by heat-treating fibers obtained from polymers or copolymers such as recycled cellulose, polyacrylonitrile, polyvinyl alcohol, or organic materials such as pitch and lignin under specific temperatures, atmospheres, and processing times. be done.

This heat treatment generally consists of three stages. For example, when polyacrylonitrile fibers are used as raw materials, the first stage is a process to obtain flame-resistant fibers.
A flame-retardant process in which the flame-resistant fibers are heat-treated in an oxygen-containing atmosphere at 0 to 300°C.The second stage is a process to obtain carbon fibers, and carbonization is a process in which the flame-resistant fibers are heat-treated in an inert gas atmosphere at 1,000 to 2,000°C. Step 9, the third step, is a step for obtaining graphite fibers, which is avoided from the graphitization step in which carbon fibers are heat-treated in an inert atmosphere at 2000 to 3000°C.

Of these, the graphitization process is an extremely high temperature process, so
An apparatus as shown in FIG. 1 is used which uses a carbonaceous material as a heating element.

In FIG. 1, reference numeral 1 denotes a carbonaceous tubular heating element provided with an inert gas introduction pipe 2 and an air seal plug 3, and is supported by a metal furnace wall 4.

The tubular heating element 1 is energized by a current terminal 5 to generate resistance heat, and the heating portion is heat-insulatingly coated with carbon black 7 or the like filled in the furnace body 6.

The carbon fibers 8 to be treated are transferred from an introduction roller 9 to a tubular heating element 1
After being subjected to graphitization treatment, it is drawn out by a drawing roller 10.

However, the graphitization apparatus having such a structure has the disadvantage that the heating element 1 burns out and has a short life.

As a result of extensive investigation into the cause of this, the inventors of the present invention have determined that this burnout is due to abnormal heat generation in the portion of the heating element 1 supported by the metal furnace wall 4.

In a directly energized heating element that uses a large current, such as a graphitization device, the action of the large current generates a very large magnetic field, which magnetizes the metal furnace wall in the vicinity.

The magnetized metal furnace wall generates a magnetic flux proportional to its magnetic susceptibility, which in turn acts on the heating element.

Because the effect of this magnetic flux is large in the area where the heating element is supported by the metal furnace wall, impedance locally increases,
Abnormal heat generation is caused by the interaction with large currents.

Based on this knowledge, the present invention aims to eliminate the shortcomings of conventional devices, especially abnormal heat generation, and to extend the life of the heating element.

That is, the present invention is a continuous carbon fiber consisting of a tubular heating element made of a carbonaceous material, a metal furnace wall that supports both ends of the tubular heating element, and a current-carrying terminal for supplying electricity to the tubular heating element. The graphitization apparatus is characterized in that the tubular heating element is supported by a metal furnace wall via a copper ring.

Hereinafter, the device of the present invention will be specifically explained based on the drawings.

FIG. 2 is a longitudinal cross-sectional view showing one embodiment of the present invention, with reference numeral 1
10 are the same as in FIG.

The feature of the present invention lies in the copper ring 11 provided between the tubular heating element 1 and the metal furnace wall 4.

When the tubular heating element 1 is energized, a very large magnetic field is generated due to the action of a large current, which magnetizes the copper ring 11. However, since copper has a low magnetic susceptibility, the magnetic flux acting on the annular heating element 1 is small, preventing abnormal heat generation. That's what I do.

Further, the tubular heating element 1 is also affected by the magnetic flux generated from the metal furnace wall 4, but since the effect is via the copper ring 11 with low resistance, local heat generation can be prevented.

The length and thickness of the copper ring 11 cannot be determined unconditionally depending on the magnitude of the current, the thickness of the metal furnace wall 4, the size of the tubular heating element, etc., but it is usually determined by the thickness of the metal furnace wall 4. A length of 2 to 4 times and a thickness of 0.5 to 5 mm is sufficient.

According to the device of the present invention, it is possible to prevent abnormal heat generation of the heating element and extend the life of the heating element to more than three times that of the conventional one.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a conventional graphitization apparatus, and FIG. 2 is a longitudinal sectional view showing a graphitization apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Tubular heating element, 2... Inert gas introduction pipe, 3... Seal plug, 4... Metal furnace wall, 5... ...Electricity terminal, 6...Furnace body, 7...Carbon black, 8...
・Carbon fiber, 9...Introduction roller, 10...
... Lead-out roller, 11... Copper ring.

Claims (1)

[Scope of utility model registration request] In a continuous graphitization device for carbon fiber, which comprises a tubular heating element made of a carbonaceous material, a metal furnace wall that supports both ends of the tubular heating element, and an energizing terminal for supplying electricity to the tubular heating element. . An apparatus for continuous graphitization of carbon fibers, characterized in that the tubular heating element is supported by a metal furnace wall via a copper ring.