JPS5855522A - Conveying roll for reducing gas oven - Google Patents

Abstract

PURPOSE:To improve the durability of the titled roll while inhibiting the formation of scratches on the surface of a workpiece to be treated, by telescoping a carbon sleeve having the outer layer of silicon carbide formed by reaction with Si onto the peripheral surface of a main roll body. CONSTITUTION:Si-contg. gas such as the vapor of silicon halide is supplied to the peripheral surface of a carbon sleeve and reacted with it to form a double- layered sleeve 3 having the outer layer 4 of silicon carbide. Said sleeve 3 is telescoped onto the peripheral surface of a main roll body 2 to form the titled conveying roll for a reducing gas oven. The outer layer 4 of the conveying roll obtained in this way is hardly oxidized, rich in hardness and wear resistance and tough, so that it is not easily broken down even when being affected by impact.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conveying roll disposed in a reducing gas furnace.

Rolls for transporting products installed in a reducing gas furnace that heat-treats silicon steel sheets, etc. are exposed to a high-temperature atmosphere, so oxides tend to adhere to their surfaces. There is a problem of scratches on the product. As a countermeasure against this problem, as shown in FIG. 2, a conveying roll is used in which a so-called carbon sleeve (1), which is a hollow cylindrical body made of graphite, is fitted onto the outer peripheral surface of a roll body (2).

However, the carbon sleeve (1) is oxidized in the furnace and is a relatively soft material that is easily abraded, so it has the drawback of lacking durability. Further, as the surface becomes rough, it causes scratches on the surface of the article to be treated, and the original purpose of using the sleeve is quickly lost.

The present invention solves the above problem and provides a conveying roll in which a carbon sleeve having a layer of silicon carbide is fitted onto the outer circumferential surface of the roll body.

That is, in the conveying roll according to the present invention, as illustrated in FIG.
) has a concentric two-layer structure.

The above-mentioned two-layer carbon sleeve (hereinafter referred to as "two-layer sleeve") (3) is obtained by molding a graphite material (for example, an artificial graphite electrode may be used) that is used in the production of conventional carbon sleeves. It is manufactured by reacting the outer layer of a hollow cylindrical body (of course, a commercially available carbon sleeve may be used as is) with silicon to convert it into silicon carbide, and leaving the inner layer unreacted (graphitic). be able to.

In the reaction with silicon to form the silicon carbide outer layer (4), a silicon-containing gas, such as a silicon halide (SiC14, SiBr4, S
iI4, etc.), and the temperature is about 1300 to 24
This can be carried out by holding the temperature at 00°C for about 1 to 50 hours.

The outer peripheral surface of the thus obtained two-layer sleeve (3) is made of silicon carbide, which is highly hard and wear-resistant, and is resistant to oxidation.
Even when used repeatedly in a reducing gas furnace, there is little wear and tear and the surface is less likely to become rough. Moreover, the hard silicon carbide outer layer is bonded to the soft graphite inner layer, and the bonding force between the two layers is extremely strong, so it is strong and will not easily break even when subjected to impact.

The total thickness of the two-layer sleeve (3) is determined to avoid the conventional carpones, the disadvantage that the silicon carbide forming reaction requires a long time, and the peeling caused by the increase in the thickness of the silicon carbide layer. Generally, an upper limit of about 2 mm is appropriate.

In addition to the two-layer sleeve obtained by the reaction of a carbon sleeve and silicon as described above, for example, a mixed material obtained by adding an appropriate binder to silicon carbide powder and graphite powder may be used. It is also possible to use a sleeve obtained by molding two concentric layers using a suitable pressure molding machine.

Next, an example of the conveyance roll of the present invention will be described.

Example A commercially available carbon sleeve (length 2000 mm, wall thickness 30 mm) was reacted with a silicon-containing gas from its outer peripheral surface to form an unreacted silicon carbide outer layer with a layer thickness of 0.5 to 1.5 mm. A sleeve was obtained having two concentric layers consisting of a graphitic inner layer.

The above reaction conditions are as follows.

Silicon-containing gas: SiBr4/SiI4 (% ratio 2:
3 to 5:1), mixed gas pressure 50 to 10,000 degrees H7 reaction temperature: 1B00 to 2,400°C reaction time: 5 to 50 hours' It was fitted onto the outer peripheral surface of a 200 ONff length, and placed in a silicon steel plate heat treatment furnace (atmosphere: 275% N, 225% H; temperature: 850-900°C).

As a result, during repeated use, there is less wear and tear on the sleeve surface and less surface roughness than with conventional carbon sleeves (
The lifespan is about 1.5 times longer than that of a roll fitted with a roll (same as the one used in the production of the two-layer sleeve of the present invention),
Throughout the period of use, there was virtually no occurrence of flaws on the surface of the article to be treated due to surface roughness of the sleeve.

As described above, the conveying roll of the present invention is unlikely to cause deterioration of the sleeve, has excellent durability, prevents the occurrence of scratches on the surface of the processed article, and maintains good surface quality during long-term use. Guarantee.

The conveying roll of the present invention can be used not only in a silicon steel sheet heat treatment furnace but also in various other heat treatment furnaces to achieve the same effects as described above.

[Brief explanation of drawings]

FIG. 1 (1) is a schematic side cross-sectional view showing a specific example of the conveying roll of the present invention, (1) is a cross-sectional view taken along line A-A thereof, and FIG. 2 (1) is a schematic side cross-sectional view showing a conventional conveying roll. Figures 1 to (I) are sectional views taken along the line AA. (1)...carbon sleeve, (2)...roll body, (3)...two-layer sleeve, (4)...outer layer, (5)...inner layer. Patent applicant Kubota Tekko Co., Ltd. Agent Patent attorney Miyazaki Shinhachibe Figure 1 Figure 2 (n)

Claims (2)

[Claims] (1) A transport roll for a reducing gas furnace, characterized in that a carbon sleeve having a silicon carbide outer layer formed by reaction with silicon is fitted onto the outer peripheral surface of the roll body. (2) The transport roll for a reducing gas furnace as described in item 1 above, wherein the silicon carbide outer layer has a thickness of 2III or less.