JPS5881920A - Fused silica roll for heat-treating furnace - Google Patents

Abstract

PURPOSE:To project inhibiting the formation of build-up, by grooving the outer surface of a ceramic roll obtained by forming and sintering silica particles. CONSTITUTION:The titled roll is formed by comprising a ceramic roll obtained by sintering and bonding silica particles as a main component and having an outer surface on which grooves are formed by mechanical engraving. The grooves 5 of the roll do not come in contact with a strip, but the flat surfaces of crowns 4 only come in contact with the strip and effectively work to suppress build-up. Consequently, the formation of build-up is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roll surface profile that reduces and prevents build-up in a fused silica roll for continuously heat treating metal strip.

Rolls for continuous heat treatment of strips such as silicon steel plates, stainless steel plates, galvanized iron plates, etc. are rolls made of heat-resistant alloy or those whose surfaces are thermally spray coated, asbestos rolls with asbestos laminates crimped around the shaft, or Car around axis 1 as shown in Figure 1? There are ceramics, crawlers, etc. equipped with a ceramic sleeve 2 made of silica or fused silica. The usage conditions such as temperature and atmosphere vary depending on the material and purpose of the heat-treated object, and they are used depending on these conditions, but at present there is still no product with fully satisfactory characteristics. be.

Compared to the other rolls mentioned above, fused silica rolls have higher heat resistance and
Excellent wear resistance and thermal expansion coefficient of 0.04% at 1000℃
Because of its extremely small size, it has great spool resistance and has the ability to withstand temperature changes caused by rapid loading and unloading of rolls into the furnace. It also has superior build-up resistance, which is the most important property for rolls, compared to others.

However, this does not mean that there will be no adhesion from metal strips or pools or build-up under all conditions, and some adhesion will occur. In most cases, the degree of adhesion is small, and once the adhesion has progressed to a certain extent, it is easily removed by friction with the next strip, but there are cases where the surface condition of the roll is not suitable. This invention provides a fused silica roll for heat treatment furnaces that reduces and prevents build-up.

The inventors focused on the fact that fused silica rolls have low reactivity and wettability with deposits from IJ, and once the deposits have progressed to a certain extent, they peel off due to the frictional force with the next strip. , the shape of the roll surface that most efficiently removes deposits, that is, the cross section parallel to the axial direction has an uneven shape, the recesses (hereinafter referred to as grooves 5) do not contact the strip, and the protrusions (contributors) It has been found that a shape in which only the flat surface of the strip (referred to as ``falling mountain 4'') is in contact with the strip is extremely effective in suppressing pill door and zo.

However, in this case, the maximum effect will be achieved if the following conditions are satisfied. .

1) Width of one mountain in contact with the strip is 0.5-3m
(A in Figure 2).

2) The distance between the ends of the peaks on both sides of one groove is 1 to 5 cm (II in Figure 2). 3) The depth of the groove is 0.1- or more (Second Figure C).

Such grooves are mechanically processed to exhibit fine, periodic, or irregular irregularities within the above conditions.

Examples of the present invention will be described below.

The outer surface of a fused silica roll with an outer diameter of 150 cm, an inner diameter of 100 cm, and a length of 1500 cm was grooved, and the width of the ridges was A x 2 ms, the distance between the ridges B = 2 cm, and the depth of the grooves was C-1-. . The surface roughness of the flat part of the mende is! , 10 μRs (L z 16
wm )・The physical properties of the roll are as follows: apparent porosity 10.57. Bulk specific gravity 194. The compressive strength was tosoky/aJ. Therefore, it was tested at 500°C or higher in a heat treatment test furnace. A roll manufactured under the same conditions but not grooved was placed at the same time for comparison.The latter grooved roll had a brownish-brown color in its entirety in contact with the strip after 10 days of use. There was a lot of deposits attached, and the accumulation progressed with the passage of days, and some build-up occurred after 3 months. On the other hand, in the case of the former grooved roll, similar deposits were found adhering to the flat surface of the mountain after 10 days, but no buildup was observed after that, and there was no change even after 6 months, and no build-up occurred at all. Moreover, there was no adhesion at all in the groove portion. Although the above is just one example, tests were repeated using the same method on rolls with different groove shapes.

When the conditions are not severe, for example when the heat treatment temperature is low, there is no significant difference between the grooved and non-grooved ones, and both have good results, but when the heat treatment temperature exceeds 800℃, The more severe the conditions, the more noticeable the difference becomes.

The width of the mountain is large J) The effect decreases when it exceeds 5m0
This is because the connected area of the deposits that have adhered and accumulated on the roll surface becomes large, which causes them to easily peel off and become difficult to be removed by friction with the next strip. Furthermore, if the width of the ridges is made too small, the ridges will wear out in a short period of time, and the effect of the grooves will essentially become weaker. □ If the distance (B) between the peaks on both sides of one groove is too large, it is not preferable because it causes partial deformation of the strip in the case of a thin strip. Also B is 1111
The following is difficult to manufacture and process, and is naturally limited.

If the depth Q of the groove is less than 0.1 II, it will not be effective as a groove. Therefore, the depth should be 0.111 or more and should be appropriately determined by the dimensions A and B, taking into consideration the strength of the silol material.

Further, the cross-sectional shape of the groove may be determined as appropriate in consideration of the processing method and the strength of the roll material.

In addition, FIG. 3 shows another embodiment in which appropriate radii are provided in the concave and convex portions.

As described above, by forming the roll surface into a grooved shape according to the present invention, it has become possible to reduce and prevent the occurrence of build-up.

The roll material is A/205 fused silica.

ZrO”StO* ZrO2s CaO* MgOa
Cr2O5 Part 2 It is natural that materials to which other components are added have similar effects, as long as their chemical and physical properties are similar to those of fused silica stone.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a roll for a heat treatment furnace, FIG. 2 is an enlarged view of the main part showing a fused silica roll for a heat treatment furnace in an embodiment of the present invention, and FIG. 3 is a heat treatment in another embodiment of the present invention. FIG. 2 is an enlarged view of the main parts of a fused silica roll for a furnace. 1... Shaft, 2... Fused silica roll, 3... CI
-/l/outer surface, 4...mountain, 5...groove. Applicant's agent Patent attorney Takehiko Suzue Figure 2 85

Claims (1)

[Claims] A fused siliceous roll for a heat treatment furnace 0, characterized in that mechanically processed grooves are carved on the outer surface of the roll mainly composed of sintered and bonded fused silica.