JPH0896940A - Ceramic heater - Google Patents

Abstract

PURPOSE: To provide a barrel-shaped ceramic heater which can perform equal heating even in case that the position of passage of a thread product deflects, and is fit for heat-treating a plurality of products at the same time. CONSTITUTION: This is a ceramic heater where a heating wire 2 is buried in spiral shape inside a ceramic barrel 1. This sectional form of the inner face of this barrel 1 is made elliptic or rectangular. Besides, it is desirable to set the value of the major axis minor axis of the inner face of the barrel 1 to 3/1 to 5/4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cylindrical ceramic heater.

[0002]

2. Description of the Related Art Ceramic heaters in which a heating wire is embedded in a ceramic base have been known for a long time. As one of them, a ceramic heater based on a ceramic cylindrical body has been proposed. Such a cylindrical ceramic heater is used to heat-treat a thread-shaped or wire-shaped product at a high speed while allowing the product to be heat-treated therein. Kaihei 6-20
There is one described in Japanese Patent No. 8885. However, since the ceramic cylindrical bodies used in the conventional cylindrical ceramic heater of this type are all cylindrical, there are the following two problems.

First, in order to equalize the temperature of thread-shaped or wire-shaped products, a ceramic heater is set so that these products pass through the center of a ceramic cylinder, but the speed and unit length of the product are set. If the weight per contact changes, the centrifugal force acting on the product (the product moves like a loop between rollers, centrifugal force acts) changes, and the product moves in a specific direction from the center of the ceramic cylinder. May swing to.
As a result, the product approaches one wall surface of the ceramic cylindrical body and separates from the opposite wall surface, so that only one surface of the product is strongly heated and uniform heating cannot be performed.

Secondly, when a plurality of products are to be heat-treated at the same time, a partition plate is inserted inside to prevent the products from contacting each other (for example,
(See Japanese Patent Application Laid-Open No. 6-208886, filed by the applicant of the present invention), the ceramic cylinder requires secondary processing, which increases the manufacturing cost of the ceramic heater. Moreover, since the diameter of the cylinder must be increased, the heater as a whole becomes large in size, which increases manufacturing cost and power consumption, resulting in increased running cost.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and can perform uniform heating even when the passing position of the product is shaken by centrifugal force or the like, and at the same time, a plurality of products The present invention has been made in order to provide a cylindrical ceramic heater capable of minimizing an increase in the manufacturing cost and running cost of the ceramic heater even when heat treatment is performed.

[0006]

The ceramic heater of the present invention, which has been made to solve the above-mentioned problems, is a ceramic heater in which a heating wire is embedded in a spiral shape inside a ceramic cylindrical body. The cross-sectional shape of the inner surface is oval or rectangular. In addition, the value of the major axis / minor axis of the inner surface of the above-mentioned cylinder is set to 3/1.
It is preferably set to 5/4.

[0007]

In the ceramic heater according to the present invention, the inner surface of the cylindrical body has an oval or rectangular cross section. Therefore, if the direction of the major axis is set in a direction in which the passing position of the product may be shaken by centrifugal force or the like. Even if the passing position of the thread-shaped or wire-shaped product is changed, it is possible to perform substantially uniform heating. In addition, when passing multiple thread-shaped or wire-shaped products in the direction of the major axis, it is possible to secure the distance between the products and it is cheaper than the conventional method of inserting a partition plate. Can be manufactured. Furthermore, since it is sufficient to increase the size only in the major axis direction, it is possible to suppress an increase in running cost.

[0008]

The present invention will be described below in more detail with reference to the illustrated embodiments. In FIGS. 1 and 2, reference numeral 1 is a ceramic cylindrical body, and 2 is a heating wire embedded therein in a spiral shape. In the embodiment, the heating wire 2 is wound around the groove on the outer circumference of the cylindrical body 1 and is embedded by covering the outer circumference with the slurry-like ceramic 3. Example cylinder 1
The material of the cordierite is the cordierite and the heating wire 2 is the nichrome wire, but these materials can be changed arbitrarily.

In the present invention, the inner surface of the ceramic cylinder 1 has an oval shape (including an elliptical shape, a track shape, etc.) or a rectangular shape. In this embodiment, as shown in FIG. 2, the cross section of the inner surface of the ceramic cylinder 1 is elliptical. If the cross-sectional shape of this inner surface approaches a perfect circle, the same drawbacks as the conventional product will occur. On the contrary, if it becomes too slender, the radiant heat from the long diameter side will be insufficient, and as with heating from two directions by two flat plates, Uniform heating from the circumference becomes difficult. Therefore, the value of the major axis / minor axis of the inner surface of the cylinder 1 is 3/1
It is preferable to be ~ 5/4, in the example, the major axis is 23 mm,
The minor axis is 13 mm and the major axis / minor axis values are almost 9/5.

One ceramic heater of this type is
50 to 1000 W is common. Also, the minor axis of its inner surface is
It is usually 10 to 80 mm and the length is 125 to 1000 mm. Both ends of the heating wire 2 are connected to a lead wire 5 covered with a bead insulator 4, as shown in FIG. And in the embodiment, the cylindrical body 1
The inner surface temperature is about 700 ℃.

The ceramic heater having the above-described structure is designed to uniformly heat the entire circumference of the ceramic heater while allowing the thread-shaped or wire-shaped product 10 to pass through the center of the ceramic heater at a high speed as shown in FIGS. used. At this time, as described above, the centrifugal force changes due to changes in the speed and weight per unit length of the product 10, and the passing position of the product 10 may fluctuate as shown in FIG. However, in the present invention, since the inner surface of the cylindrical body 1 has an oval or rectangular cross-sectional shape, even if the product 10 shakes as shown in FIG. 2, the distance from the surrounding wall surface does not change so much and almost uniform heating is achieved. It can be carried out.

Further, the ceramic heater thus constructed has a plurality of products 10, as shown in FIG.
These can be heated by passing them through 10 at the same time, but in this case as well, since the inner surface of the cylinder 1 has an oval or rectangular cross-sectional shape, it is possible to secure a sufficient interval between the plurality of products 10, 10. it can. Moreover, since it is not necessary to provide a partition plate inside the tubular body 1, the manufacturing is easy, and since the size of the tubular body 1 may be increased only in the major axis direction, an increase in manufacturing cost can be suppressed and running The cost can also be reduced.

[0013]

As described above, in the ceramic heater of the present invention, since the cross-sectional shape of the inner surface of the ceramic cylindrical body is oval or rectangular, the passing position of the product is different from the conventional product. There is an advantage that uniform heating can be performed even when shaken, and an increase in manufacturing cost and running cost of the ceramic heater can be suppressed to the minimum even when a plurality of products are heat-treated at the same time. Therefore, the present invention is highly valuable as a ceramic heater that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a usage state.

FIG. 3 is a cross-sectional view showing another usage state.

[Explanation of symbols]

1 Ceramic cylinder, 2 Heating wire, 3 Ceramic, 4 Bead insulator, 5 Lead wire, 10 Thread-shaped, wire-shaped product

Claims (2)

[Claims] 1. A ceramic heater in which a heating wire is embedded in a spiral shape in a ceramic cylindrical body, wherein the cross-sectional shape of the inner surface of the cylindrical body is oval or rectangular. 2. The value of the major axis / minor axis of the inner surface of the cylinder is 3/1 to 5 /
4. The ceramic heater according to claim 1, wherein