JP2693372B2 - Ceramic roller for rolling line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide roller and a rolling roll used in a hot rolling line for producing a wire rod such as a steel strip and a steel pipe. More specifically, the present invention relates to a guide roller and a rolling roll which are not easily damaged during rolling and have improved durability. Ceramic guide roller and rolling roll.

[0002]

2. Description of the Related Art Conventionally, a guide roller or a rolling roll (hereinafter, both the guide roller and the rolling roll are abbreviated as "roller") used in a hot rolling line for manufacturing a steel strip, a steel pipe or the like is made of metal. Have been widely used. However, such a metal roller is liable to wear in such a hot rolling and has a short life, and since the heat resistance is insufficient, it is likely to cause seizure in contact with the material to be rolled, and further, Due to the heavy weight of the roller itself, it was not easy to install or replace it.

Therefore, in recent years, a ceramic roller utilizing the excellent wear resistance, heat resistance, and lightness of ceramics has attracted attention and various studies have been conducted. Here, an example of a conventional ceramic roller is shown in FIG.
In the figure, the ceramic roller 1 is configured by providing a roller main body 10 with a bearing loading portion 12 and a spacer loading portion 14. Then, as shown in FIG. 6, such a ceramics roller 1 has a bearing loading portion 12 and a bearing 2
0, the spacer 30 is loaded in the spacer loading unit 14, is attached to the shaft 40 via the bearing 20, and is installed in a part of the rolling line.

[0004]

However, in such a conventional ceramics roller, as shown in FIG. 3, the bottom peripheral edge portion 12e of the bearing loading portion 12 remains in an acute angle shape (see FIG. 7). Therefore, when such a roller 1 is attached to a rolling line as shown in FIG. 6, the bottom peripheral edge portion 12e is apt to crack due to an impact load by the material to be rolled (steel material), and the roller 1 is broken in some cases. There was a problem to be done. The present invention has been made in view of the above problems of the prior art, its main purpose is to resist the impact load of the material to be rolled, hard to break, durability It is to provide an excellent ceramic roller. It has also been found that when manufacturing the ceramic roller as described above, it takes time and labor to process the roller, which may damage the grinding tool. Therefore, another object of the present invention is to provide a ceramic roller which is easy to process and which is unlikely to damage a grinding tool or the like.

[0005]

As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by forming the above-mentioned bottom peripheral portion into a specific shape, and the present invention has been completed. Came to do. Therefore, the ceramic roller of the present invention is a ceramic roller used in a hot rolling line, in which a bearing is loaded in the bearing loading portion, and the bottom peripheral edge of the bearing loading portion has a radius of curvature of 0.5 mm or more. It is characterized by having.

[0006]

In the present invention, the bottom peripheral edge portion of the bearing loading portion of the roller body is formed so that the radius of curvature is 0.5 mm or more. Therefore, the stress due to the impact load of the material to be rolled is unlikely to concentrate on the bottom peripheral edge, and the bottom peripheral edge is unlikely to be damaged.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 is a partially enlarged cross-sectional view of a ceramic roller showing an embodiment of the present invention, and shows the same portion as FIG. In the figure, the bottom peripheral edge portion 12a of the bearing loading portion 12 is formed to have a radius of curvature of 0.5 mm or more. Therefore, even if this ceramic roller is installed in a rolling line as shown in FIG. 6 and rolling is performed, the stress due to the impact load of the material to be rolled such as steel material is hard to concentrate on the bottom peripheral edge portion 12a, and the bottom peripheral edge portion 12a. Can be prevented from being damaged.

The radius of curvature of the bottom peripheral edge portion 12a is 0.5.
It is sufficient that the thickness is 1 mm or more, but 1 mm or more is preferable. If the thickness is less than 0.5 mm, cracks originating from the peripheral edge of the bottom may occur during use, or the roller may be damaged, which is not preferable.

Next, another embodiment of the present invention is shown in FIG.
In the figure, in the bottom peripheral edge portion 12b , the recessed portion 1
Has a 2b ', the direction of the recessed, as shown in FIG. 3 is a partially enlarged view of FIG. 1, the curved processed bottom periphery 1
It is the direction of the normal line A in the most recessed part of 2a. by the way,
In the bottom peripheral edge portion 12a, there are innumerable normals as shown by arrows A ₁ , A ₂ and A ₃ , but the concave direction of the bottom peripheral edge portion is defined by the normals A ₁ and A at the inflection point. _The direction indicated by any normal existing between ₂ and can be adopted. Therefore , the recessed portion 12 in the bottom peripheral portion 12b
As a modified example of b ′ , the one shown in FIG. 4 (a) or FIG. 4 (b) can also be mentioned. However, the bottom peripheral portion 1
It is more preferable that the groove 2b is provided in the direction A in order to avoid the stress concentration most effectively.

Further, as the ceramic material constituting the ceramic roller of the present invention, silicon nitride, silicon carbide,
Examples include sialon, alumina, zirconia,
Of these, silicon nitride is preferable, and particularly, the Vickers hardness at room temperature is 1100 to 1600, preferably 1200 to 140.
800-1,400 at 0, 800 ° C, preferably 900-
1200, and the four-point bending strength defined by JIS R 1601 is 700 to 1200M at room temperature to 800 ° C.
More preferred is silicon nitride, which is Pa. If the Vickers hardness is less than 1100, the roller wear becomes large,
If it exceeds 600, the steel material is likely to be scratched, and if the 4-point bending strength is less than 700 MPa, the roller cannot withstand the impact force of the steel material and is easily broken, which is not preferable.

The roller body 10 made of ceramics can be manufactured by a conventionally known method using a predetermined raw material. Further, the shape of the roller body 10 may be given by grinding after sintering, but such grinding after sintering takes time due to the hardness of the ceramics and the like, and the grinding tool is damaged. The roller body 10 is formed into a predetermined shape before firing in consideration of firing shrinkage of the body.
It is preferable to give the final shape to. This means that it is preferable that the roller main body 10 is constituted by an as-fired surface (hereinafter referred to as a "fired surface") that is not subjected to grinding after firing.

In particular, the inner surface of the roller body 10, that is, the bearing loading portion 12 and the spacer loading portion 14 are preferably given a predetermined shape before firing as described above, and the bottom peripheral edge portions 12a and 12b are also provided with this shape. As described above, it is more preferable to give a predetermined shape and configure the firing surface. That is, the curved surface processing of the bottom peripheral edge portions 12a and 12b can also be performed by grinding using an R-shaped grindstone after firing, but the bottom peripheral edge portion is processed by grinding processing after sintering in this way. In this case, since plunge processing (processing in which a grindstone is pressed against the same portion) is required, processing scratches due to the grindstone are likely to occur on the bottom peripheral edge portion, which may rather reduce the strength, which is not preferable. Therefore, in consideration of the shrinkage of the molded body (in this case, the bottom peripheral edge portion), the bottom peripheral edge portion is formed into a predetermined shape before firing, and after firing, the portion where dimensional accuracy is strictly required (other than the bottom peripheral edge portion) It is preferable to grind only a portion, for example, the inner diameter portion of the bearing loading portion.
At this time, the bottom peripheral edge portion 12b is configured by recessing and curved surface processing as described above in the processing before firing, and in the grinding processing after firing, the bottom peripheral edge portion is prevented from hitting the grindstone. According to this method, the processing scratches generated on the bottom peripheral edge portion by the pre-baking processing are erased (healed) by the baking, and the processing scratches are not introduced on the bottom peripheral edge portion even in the processing after the baking.
A roller with higher reliability can be obtained.

As a method for imparting a shape to the bottom peripheral edge portions 12a and 12b before firing, after molding, the molded body is 400-50.
A method of calcination at 0 ° C. to remove the binder and then lathing can be mentioned. At this time, the surface roughness of the calcined body is Rmax of 10 μm or less, preferably 6 μm.
It is desirable to control as follows. Further, since the ceramic shrinks about 10 to 30% in volume during firing, it is desirable that the radius of curvature of the bottom peripheral edge portion be 0.6 mm or more, preferably 1.2 mm or more in the pre-firing process. . In addition, although a full-scale tool can be used for curved surface processing of the bottom peripheral edge, NC processing with a normal edge-shaped tool reduces chipping of the processed surface, scratches, etc., and has reproducibility. Since it is also excellent, processing by such an edge-shaped cutting tool is preferable.

(Example 1) 5% by weight of MgO as a sintering aid, 5% by weight of CeO ₂ , and 2% by weight of silicon nitride raw material were used as a sintering aid.
SrO and a predetermined amount of binder were added, mixed with a mixer, and then dried and granulated with a spray dryer. The obtained granulation raw material was filled in a mold composed of a mold for molding a central hole and a rubber mold for molding outside, and was molded at a pressure of 3.0 t / cm ² by a hydrostatic pressing machine. Individual molded bodies were produced. Next, these compacts were processed into a predetermined shape with an NC lathe, calcined at 400 ° C. in the air to remove the binder, and then calcined at 1700 ° C. for 1 hour in a nitrogen atmosphere under atmospheric pressure to obtain a sintered body. .

The obtained sintered body was roughly processed with a # 140 metal bond diamond grindstone, and using a # 240 metal bond diamond grindstone, an outer diameter of 80 × an inner diameter of 40 × a length of 6
The finish was 0 mm and the curvature of the caliber portion was 50 mm. Then, at this time, the bearing loading portion was finished with a # 240 metal bond diamond grindstone having six kinds of curvatures whose edge portions were 0.1 to 2.0 mm. By grinding as described above, two silicon nitride rollers each having six types of curvatures were produced at the bottom peripheral edge of the bearing loading portion, for a total of 12 rollers.

When the surface roughness (maximum height defined in JIS B 0401) of the bearing loading portion of each roller thus obtained was measured, the average values at five points on the inner surface of the bearing loading portion were 2.8 to 3. It was 2 μm, while the average value at 5 points on the bottom edge was 3.4 to 4.2 μm, respectively.
Met. Further, the curvature of the bottom peripheral edge portion measured by the shape measuring machine was 0.10 to 2.05 mm, respectively. An angular type cylindrical roller bearing is loaded in the bearing loading portion of each roller, and it is attached as an inlet roller guide of an SCM alloy hot rolling line intermediate rolling mill (roller caliber diameter 50 mm).
An SCM alloy having a final wire diameter of 10 mm was rolled. The roller was removed at every rolling amount of 500 tons, and the presence or absence of damage was confirmed by fluorescence penetration flaw detection. Table 1 shows the obtained results.

Example 2 Twelve molded bodies were prepared in the same manner as in Example 1, each was processed into a predetermined shape by an NC lathe, and then calcined in the air at 400 ° C. to remove the binder. The bearing loading portion of the obtained calcined body was processed by an NC lathe, and the radius of the bearing loading portion was 0.13 to 2.48 m at the bottom peripheral edge portion.
A curvature of m was formed. Next, these calcined bodies were fired at 1700 ° C. for 1 hour in a nitrogen atmosphere at atmospheric pressure to obtain sintered bodies.
The obtained sintered body was roughly processed with a # 140 metal bond diamond grindstone, and subsequently using a # 240 metal bond diamond grindstone, the outer diameter was 80 mm, the inner diameter was 40 mm, the length was 60 mm, and the curvature of the caliber portion was 50 mm. Finished so that As described above, the bottom peripheral portion of the bearing loading portion was composed of the calcined surface, and two rollers of each of 6 types having different curvatures were manufactured, 12 rollers in total.

With respect to each of the obtained rollers, the surface roughness and the curvature of the bottom peripheral portion were measured in the same manner as in Example 1. The average value of the surface roughness at the five locations on the inner surface of the bearing loading part was 2.8 to 3.2 μm, and the average value of the surface roughness at the bottom peripheral portion was 3.8 to 5.4 μm, respectively. Moreover, the curvature of the bottom peripheral portion was 0.10 to 2.0 mm, respectively. As in Example 1, the roller was attached to a rolling line and the performance of each roller was evaluated. Table 1 shows the obtained results.

(Comparative Example) The same operation as in Example 1 was carried out,
A silicon nitride sintered body was obtained, and the obtained silicon nitride sintered body was roughly processed and finished with a diamond grindstone. However, the bottom peripheral edge of the bearing loading portion was finished with a normal diamond grindstone having no curvature on the edge. For each of the obtained rollers, the surface roughness and the curvature of the bottom peripheral portion were measured in the same manner as in Example 1. The average value of the surface roughness at the five points on the inner surface of the bearing loading portion is 2.6 to 3.0 μm, and the average value of the surface roughness at the bottom peripheral edge portion is 3.5 to 4.3, respectively.
μm. The curvature of the bottom peripheral edge is 0.0
It was 3 to 0.05 mm. As in Example 1, the roller was attached to a rolling line and the performance of each roller was evaluated. Table 1 shows the obtained results.

[0020]

[Table 1]

As is clear from Table 1, the ceramic roller having a radius of curvature of the bottom peripheral portion of the bearing loading portion of less than 0.5 mm is damaged by the rolling amount of several hundreds to several thousand tons or the bottom peripheral portion is damaged. While a crack occurred,
A roller with a curvature of 0.5 mm or more at the bottom edge is 10,000
Even if the steel material of t was rolled, no abnormality occurred at all.

[0022]

As described above, according to the present invention,
Since the bottom peripheral edge portion of the bearing loading portion has a specific shape, it is possible to provide a ceramic roller that is resistant to the impact load of the material to be rolled, is not easily broken, and has excellent durability.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of a ceramic roller of the present invention.

FIG. 2 is a partial cross-sectional view showing another embodiment of the ceramic roller of the present invention.

3 is a partial enlarged sectional view of FIG.

FIG. 4 is a partial sectional view showing still another embodiment of the ceramic roller of the present invention.

FIG. 5 is a sectional view showing an example of a conventional ceramic roller.

6 is a cross-sectional explanatory view showing a state in which the roller shown in FIG. 5 is attached.

FIG. 7 is a partially enlarged sectional view of the roller shown in FIG.

[Explanation of symbols]

1 ceramic roller, 10 roller body, 1
2 bearing loading part, 12a, 12b, 12e bottom peripheral edge part, 14 spacer loading part, 20 bearing, 30
Spacer, 40 axis

Claims (4)

(57) [Claims] 1. A ceramic roller for use in a hot rolling line, comprising a bearing loading portion for loading a bearing, and a bottom peripheral edge portion of the bearing loading portion has a radius of curvature of 0.5 mm or more. Ceramic roller. 2. The ceramic roller according to claim 1, wherein the bottom peripheral edge portion is constituted by a fired surface. 3. A said bottom peripheral edge, according to claim 1 or 2 ceramic roller, wherein Rukoto that have a recessed portion which is recessed in any direction normal to the bottom periphery. 4. The cell according to any one of claims 1 to 3.
Be sure to equip the bearing loading part of the Ramix roller with a bearing.
Characteristic ceramic roller with bearing .