JP2693364B2 - Ceramic rotating jig - 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, a conveying roller, used in a hot rolling apparatus for iron, iron alloys, etc.
The present invention relates to a ceramic rotating jig such as a plain bearing.

[0002]

2. Description of the Related Art Conventionally, metal jigs have mainly been used as rotary jigs for guide rollers, conveying rollers, sliding bearings and the like used in hot rolling apparatus for iron, iron alloys and the like.
However, the metal rotating jig has a problem that it is liable to wear and has a short life and has insufficient heat resistance, so that it easily contacts with the material to be rolled and causes seizure. Furthermore,
Since the jig itself is heavy, it was not easy to install or replace it. For this reason, in recent years, research and development have been actively conducted on ceramic rotary jigs that utilize the excellent wear resistance, heat resistance, and lightness of ceramic materials.

[0003]

However, since ceramics is a brittle material, when a rotating jig is constructed by attaching a metal shaft to a ceramic roller having a bearing hole by loose fitting, stress is not generated during operation. There is a problem that cracks are likely to occur at the contact end portion of the bearing hole where the metal is concentrated with the metal shaft, and the crack causes the jig to break in a relatively short period of use. As with the ceramic roller 1 shown in FIG. 4, attempts have been made to reduce the stress by applying C removal to the contact end of the bearing hole 2 with the metal shaft, but the actual improvement effect has not been obtained. Is. The present invention has been made in view of the above-mentioned problems of the conventional technology, and an object thereof is to prevent occurrence of cracks at a contact end of a bearing hole with a metal shaft and damage due to the occurrence of cracks. , To provide a rotating jig made of ceramic that can be stably used for a long period of time.

[0004]

In order to achieve the above object, according to the present invention, a ceramic rotary jig comprising a ceramic roller having a bearing hole and a metal shaft mounted in the bearing hole by a clearance fit. The bearing hole and the metal shaft are in contact with each other by a clearance fit at the inner diameter straight portion of the bearing hole with a clearance δ and a contact length L.
When touched, the distance between the bearing hole and the metal shaft smoothly increases at a portion having a length l outside the contact end.
A shape, the length 1 is equal to the clearance δ and
There is provided a ceramic rotating jig defined by a contact length L and satisfying the following expression .

(Equation 1) 0.0006 ≦ l · δ / L ≦ 0.006

[0005]

FIG. 1A is a sectional view showing an example of the present invention.
FIG. 1B is an enlarged view of the main part. The present invention will be described below with reference to these figures. The ceramic rotating jig of the present invention includes a metal shaft 3 of a bearing hole 2 of a ceramic roller 1.
Since the separation distance between the bearing hole 2 and the metal shaft 3 is smoothly increased at a portion outside the contact end portion with the contact stress, the stress at the contact end portion is relieved, and cracks are generated and caused. The jig is prevented from being damaged.

[0006] In the present invention, the bearing hole 2 and the metal length l of the outer portion from the contact end which is adapted distance increases smoothly with the shaft 3, the plow between fitting clearance δ and the bearing hole 2 Is defined by the contact length L between the metal shaft 3 and the metal shaft 3, and it is important that the following formula 1 is satisfied.
You .

## EQU1 ## 0.0006 ≦ l · δ / L ≦ 0.006

In the ceramic rotary jig having a shape satisfying such a relationship, the contact end portion between the bearing hole and the metal shaft is not subjected to any treatment, and the end portion of the bearing hole is C-cut. It was confirmed that the service life was significantly improved compared to the applied one. When l · δ / L is less than 0.0006, the contact surface pressure between the metal shaft and the bearing hole at the edge portion becomes high, so that cracks easily occur at the end portion of the bearing hole due to repeated fatigue during operation. On the other hand, when l · δ / L exceeds 0.006, the clearance δ between the metal shaft and the bearing hole increases or the contact length L decreases, so that the vibration of the jig during operation increases and the bearing It may lead to damage such as, and may adversely affect the finish accuracy of the product. Further, in the present invention, it is more preferable to set the length l so as to satisfy the following expression 2.

[Formula 2] 0.001 ≦ l · δ / L ≦ 0.003

Specifically, as shown in FIG. 1, the jig shape as described above is, as shown in FIG. 1, a bearing hole 2 at a portion having a length l outside the contact end between the bearing hole 2 and the metal shaft 3. Has a shape that smoothly spreads from the straight portion of the inner diameter of the bearing hole 2, or, as shown in FIG. 2, at a portion having a length l outside the contact end between the bearing hole 2 and the metal shaft 3, the metal shaft 3 is formed by forming a shape in which the straight portion of the metal shaft 3 is smoothly narrowed and narrowed. Further, both the bearing hole shape and the metal shaft shape may be the above shape.

[0009] In the present invention, d _e (diameter of the open end) diameter of the end portion of the bearing hole 2 is more than 0.5mm than the inner diameter d _i of the bearing hole 2, preferably be greater than 1 mm, preferably on the production . Further, the surface roughness of the inner surface of the bearing hole 2 can be used without any particular problem if the maximum surface roughness is 6.3 μm or less, but considering the influence on accuracy, cost, strength, etc., 1.
Most preferably, it is about 6 to 3.2 μm. As the material of the roller portion of the ceramic rotating jig of the present invention, silicon nitride is most preferable, but even a roller or the like used for a material other than the hot rolling device, such as alumina, zirconia, silicon carbide, or sialon. The same effect can be expected.

Ceramic rotating jigs used in the apparatus for hot rolling include ceramic rollers such as guide rollers and conveying rollers. When the present invention is applied to these ceramic rollers, the method for connecting the bearing hole and the metal shaft is as follows. In addition to the method of supporting only with a metal shaft,
A method of arranging the bearings 4 on both sides of the roller 1 and supporting them through the metal shaft 3 can also be used.
Furthermore, the present invention is characterized in that the roller and the shaft are made of metal,
It can also be applied to a ceramic bearing which is mounted on the metal shaft by a loose fit.

[0011]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Prototype No. 1: After a predetermined binder was added to and mixed with the silicon nitride raw material powder, the mixed raw material was filled in a molding die made of a metal mold and a rubber mold, and sealed. This was pressed with a hydrostatic press at a pressure of 3 t / cm ² and molded. The obtained molded body was attached to an NC lathe, processed into a predetermined shape, calcined at 1000 ° C. for 4 hours, and then at 1600 ° C. for 1 hour.
It was calcined for hours and sintered. Outer diameter of the obtained sintered body is 60 mm after being processed with a diamond on a cylindrical grinder.
C. A ceramic roller shape having a length of 50 mm and a caliber curvature of 30 mm was finished. Subsequently, the bearing hole portion was ground by an inner surface grinder to finish the bearing hole inner diameter to 20.03 mm. The surface roughness of the inner surface of the bearing hole was finished with a # 600 diamond grindstone so that the maximum height R _max was 3.2 μm or less. Further, the shape of the end of the bearing hole is such that the length l from the end contacting with the metal shaft to the end surface of the roller is 0.
5 mm, and the inner diameter of the open end was 22 mm, and grinding was performed to a flared shape that spreads smoothly from the inner diameter straight portion. Thus, a set of two ceramic rollers was produced.

Bearings were arranged on both sides of the ceramic roller, a metal shaft made of SKD having a diameter of 19.97 mm was attached, and then, it was attached as a guide roller to a finishing stand of a hot rolling mill of SCM type steel bar. A rolling test was conducted in which a bar of 2 t each having a finished diameter of 60 mm was continuously passed through the hot rolling mill. The results of this rolling test are shown as the length from the contact end with the metal shaft to the end face of the roller (the length of the diverging part) l, the contact length L between the bearing hole and the metal shaft, the clearance fit clearances δ and l. It is shown in Table 1 together with δ / L.

Prototype No. 2-9: the above prototype No. In the same manufacturing procedure as in No. 1, various ceramic rollers were manufactured by changing the length l from the contact end with the metal shaft to the roller end face within the range of 0.8 to 10.0 mm.
A rolling test was conducted in the same manner as in 1. The results of this rolling test are shown as the length from the contact end with the metal shaft to the end face of the roller (the length of the diverging part) l, the contact length L between the bearing hole and the metal shaft, the clearance fit clearances δ and l. The results are shown in Table 1 together with δ / L.

Prototype No. 10 to 16: Prototype No. 1
In the same manufacturing procedure as above, the length l from the contact end with the metal shaft to the roller end face, the contact length L between the bearing hole and the metal shaft, the clearance fit clearance δ and l · δ / L
Were produced to have the values shown in Table 1, respectively, and the trial production No. A rolling test was conducted in the same manner as in 1. The results of this rolling test are shown in Table 1.

Prototype No. 17: except that the end portion of the bearing hole was machined by 1.0 mm from the roller end surface to form a C shape,
The above prototype No. A ceramic roller was manufactured in the same manufacturing procedure as in No. 1, and the trial manufacture No. 1 was manufactured. A rolling test was conducted in the same manner as in 1. The results of this rolling test are shown as the length from the contact end with the metal shaft to the end face of the roller (the length of the C-cut portion) l, the contact length L between the bearing hole and the metal shaft, the clearance fit clearances δ and l. -It is shown in Table 1 together with δ / L.

Prototype No. 18 and 19: Prototype N except that the lengths of the C-cut portions were 3.0 mm and 5.0 mm, respectively.
o. A ceramic roller was manufactured in the same manner as in No. 17, and the trial manufacture No. A rolling test was conducted in the same manner as in 1. The results of this rolling test are shown as the length from the contact end with the metal shaft to the end face of the roller (the length of the C-cut portion) l, the contact length L between the bearing hole and the metal shaft, the clearances δ and l for the clearance fit. -It is shown in Table 1 together with δ / L.

[0018]

[Table 1]

As shown in Table 1, the end portion of the bearing hole is a divergent shape that smoothly spreads from the inner diameter straight portion, and N that satisfies 0.0006 ≦ l · δ / L ≦ 0.006 is satisfied.
o. 3-12, 14-16 ceramic roller is 1
Even after a rolling treatment of 000 tons, good results were obtained without cracking. Further, after the rolling treatment, the roller was removed, and the inner surface of the bearing hole was inspected by a fluorescence penetration flaw detection test, and it was found that N satisfying 0.001 ≦ l · δ / L ≦ 0.003
o. No abnormalities were observed for 4 to 7, 10, 11, 14, and 15, showing particularly excellent results. l · δ / L
Of which the value of 0.006 ≦ l · δ / L ≦ 0.006 has a lower limit value. 3 has some contact marks, and l ・
The value of δ / L has an upper limit value of 0.0006 ≦ l · δ / L ≦ 0.006. Although No. 9 and No. 12 have no abnormalities in the roller itself, the bearings are seriously damaged, and therefore are not suitable for use in the supporting method in which the bearings are arranged on both sides of the roller as in this embodiment. Be done. l
If the value of δ / L becomes larger than the range of the present invention, the bearing will be more seriously damaged, and the finished precision of the product will be adversely affected.

On the other hand, No. 1 having l · δ / L of less than 0.0006. It was confirmed that the ceramic rollers 1, 2, and 13 were broken by a relatively small amount of rolling, or that cracks were generated in a fluorescent penetrant flaw detection test. Bearing hole end shape is C
No. which is the shape. The ceramic rollers 17-19 are
In each case, a small amount of rolling treatment caused early fracture, and when the fragments were analyzed, cracks were found at the C end of the bearing hole, and it was presumed that the roller was fractured as a result. .

In the above embodiment, the end portion of the bearing hole is formed so as to spread smoothly from the inner diameter straight portion, so that the distance between the bearing hole and the metal shaft at the outer side from the contact end portion is small. Although it is configured to smoothly increase, as described above, a shape in which the metal shaft is smoothly and narrowly drawn from the straight portion of the metal shaft at a portion outside the contact end between the bearing hole and the metal shaft. It has been confirmed that the same effect can be obtained even if the distance between the bearing hole shape and the metal shaft shape is made to be the above shape so that the distance between them can be smoothly increased.

[0022]

As described above, in the ceramic rotary jig of the present invention, the distance between the bearing hole and the metal shaft smoothly increases at the portion outside the contact end between the bearing hole and the metal shaft. By doing so, the stress in such a portion is significantly relieved, and stable use can be achieved for a long period of time without the occurrence of cracks and the resulting breakage.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a ceramic rotating jig according to the present invention and an enlarged sectional view of a main part.

FIG. 2 is an enlarged sectional view of an essential part showing another example of the ceramic rotating jig according to the present invention.

FIG. 3 is a cross-sectional view showing a method of supporting a jig having bearings arranged on both sides.

FIG. 4 is a cross-sectional view showing an example of a conventional ceramic rotary jig in which a contact end of a bearing hole with a metal shaft is C-cut, and an enlarged cross-sectional view of an essential part.

[Explanation of symbols]

1 ... Ceramic roller, 2 ... Bearing hole, 3 ... Metal shaft, 4 ... Bearing

Continued on the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B65H 27/00 B65H 27/00 A

Claims (3)

(57) [Claims] 1. A ceramic rotating jig comprising a ceramic roller having a bearing hole and a metal shaft mounted in the bearing hole by a clearance fit, wherein the bearing hole and the metal shaft are straight inner diameters of the bearing hole. click in part
Contact with clearance fit with clearance δ and contact length L,
With a shape in which the distance between the bearing hole and the metal shaft increases smoothly at a portion having a length l outside the contact end.
And the length 1 is the clearance δ and the contact length.
A ceramic rotating jig defined by L and satisfying the following formula . ## EQU1 ## 0.0006 ≦ l · δ / L ≦ 0.006 2. The bearing hole has a shape that smoothly spreads from the inner diameter straight portion of the bearing hole at a portion having a length l outside the contact end between the bearing hole and the metal shaft. The ceramic rotating jig described in 1 . 3. The metal shaft has a shape which is smoothly and narrowly drawn from a straight portion of the metal shaft at a portion having a length l outside the contact end between the bearing hole and the metal shaft. The ceramic rotating jig according to claim 1 .