JPS6393419A - Hot run table roller - Google Patents

Abstract

PURPOSE:To improve a corrosion resistance and wear resistance by constituting a ceramics outer layer with a first outer layer and a second layer impregnated with a metal and fixing plural composite sleeves with specified thickness ratio of each layer to a roll shaft. CONSTITUTION:Plural ceramics-metal composite sleeves 2 are fixed to the roller haft 7 at prescribed intervals to constitute a hot run table roller 1. The sleeve 2 consists of the ceramics outer layer 3 and the metal inner layer 6. The ceramics outer layer 3 is formed with the first outer layer part 4 sintered closely and the second outer layer part 5 impregnated with the metal in pores, the metal material impregnated in the second outer layer part 5 is connected with the metal inner layer 6 metallurgically. Furthermore, the conditions of <8.0 outer diameter/thickness of the outer layer 3, >1.5 thickness of ceramics outer layer 3/thickness of the metal inner layer 6 are satisfied. In this way, a crack of the ceramics outer layer 3 caused by a thermal expansion and construction is suppressed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a roller used in a hot run table of hot rolling equipment, and more specifically to a roller used in a cooling zone (wet zone) after a header after finish rolling. Regarding preferred rollers.

<Prior art> Conventional hot run table rollers are made of ordinary steel, ordinary cast iron, and Cr-Mo steel, and a long tube body obtained by casting molten metal of these materials using a centrifugal casting method is subjected to surface heat treatment. The sleeve was made into an integrally moving sleeve by applying various processes such as overlaying and overlaying, and this was fixed to the roller shaft to form the roller.

In addition, in recent years, with the aim of improving wear resistance, highly wear-resistant composite rollers having an outer layer made of a composite of metal and ceramic particles have been realized.

<Problems to be Solved by the Invention> The above-mentioned conventional metal hot run table rollers utilize the hardness of carbides, hardened Mi weave, etc. to improve wear resistance.\Ordinary steel, ordinary cast iron Although Cr-Jio steel has excellent wear resistance, both have poor corrosion resistance and are not resistant to corrosion when used in the wet zone where cooling water is used. It had problems such as poor corrosion and wear resistance.

In addition, since the roller has a long integrally moving sleeve fixed to the roller shaft, the motorcycle is large and requires a lot of driving energy, which is disadvantageous in terms of running costs.

Furthermore, the thickness of the one-piece sleeve cannot usually be made thick due to limitations on the roller diameter, and therefore, centrifugal force casting of a thin-walled long tubular body in the country of manufacture has been required.

Rollers whose outer layer is a composite of metal and ceramic particles have problems such as selective abrasion of the metal mixed with the ceramics and chipping of the ceramic particles, and when used in the wet zone, the metal parts corrosion is a problem. Of course, if the metal part uses a high-alloy type material that has both wear resistance and corrosion resistance, the problem will be solved, but this will create a new problem of high cost.

Means for Solving the Problems> The present invention has been made for the purpose of solving the above problems, and its technical means is a sleeve consisting of a ceramic outer layer and a metal inner layer, which The ceramic outer layer is composed of a dense first outer layer part and a second outer layer part whose pores are impregnated with metal, and the metal part A impregnated in the second outer layer part is metallurgically continuous with the metal inner layer. ,and,
A plurality of ceramic-metal composite sleeves satisfying the following conditions: outer diameter/ceramic outer layer thickness 8°0, ceramic outer layer thickness/metal inner layer thickness> 1.5 are fixed to the roller shaft at intervals. The point is that it consists of

<Example> Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a hot run table roller 1 of the present invention,
A plurality of ceramic-metal composite sleeves 2 are fixed to the roller shaft 7 at predetermined intervals.

The sleeve 2 is composed of a ceramic outer layer 3 and a metal inner layer 6, and the ceramic outer layer 3 includes a dense first outer layer portion 4 made of densely sintered ceramic particles;
and a second outer layer portion 5 formed by impregnating metal into the pores of a ceramic layer sintered continuously and having a certain degree of porosity. The metal material impregnated in 5 is metallurgically continuous with the metal inner layer 6.

Ceramics include metal oxides, silicides, nitrides,
There are metal carbides, borides, etc., and in forming the ceramic outer layer, that is, the cylindrical ceramic molded body, for example, during compaction of ceramic powder particles, a portion corresponding to the dense first outer layer is made of fine particles, and a second outer layer is formed of fine particles. For the corresponding part, adjust the mixing ratio of the thermoplastic binder mixed with the ceramic particles, increase the particle size of the ceramic particles,
Further, by compacting the powder by reducing the molding pressure and firing it, a molded body for the outer layer having a porosity sufficient to form a confidential surface layer can be obtained.

In this case, the confidential first outer layer has a suitable porosity of 0 to 5%, and since this ceramic layer is used, there is no reaction between water and metal, which is a cause of corrosion, and therefore there is no corrosion of the surface. There are no cracks in the crank, etc., and therefore, the cracks on the surface are likely to fall off, etc. 1? It shows great resistance to wear and tear.

Furthermore, because of its low thermal conductivity, it has high resistance to thermal shock from hot coils.

The porosity of the second outer layer impregnated with metal gradually increases from the surface layer and is preferably 40 to 60% at the interface with the inner layer, and by doing so, the pores are impregnated with metal. The ceramic outer layer not only maintains excellent heat insulation properties, but also has improved strength and toughness, and the gradual increase in the impregnated metal allows the material to change smoothly, thereby avoiding problems such as peeling.

However, even if the porosity increases discontinuously, there is no practical problem as long as the porosity does not exceed 40 to 60%.

Note that as a general method for manufacturing porous ceramic molded bodies, a method is known in which a urethane foam having a mesh skeleton is impregnated with a ceramic slurry, and then dried, and the dried molded body is fired. The same method can also be used to form . For example, a dense layer of ceramic powder is further formed on the outer surface of the cylindrical molded body in which the urethane foam is impregnated with a ceramic slurry and dried, and then fired.

Metal impregnation (penetration) into the thus obtained ceramic outer layer molded body and molding of the metal inner layer can be easily performed by centrifugal casting.

For example, as shown in FIG. 2, the ceramic outer layer molded body 3a is fixed in a centrifugal force casting mold 8 with a fire 9 and bands 10 and 10, and in this state, the mold 8 is rotated. 7. A casting material molten metal is poured into the ceramic outer layer molded body 3a using the pouring gutter 11 to permeate into the pores of the ceramic outer layer molded body.

At this time, it is desirable to provide spaces 12, 12 as much as possible so that both end surfaces of the molded body 3a come into contact with the cast molten metal. This is because the end face solidifies quickly when cooled, making it difficult to achieve the required penetration into the ceramics.

Further, as a means for aiding penetration, it is desirable to preheat the ceramic outer layer molded body 3a to 400 to 1200°C. At this time, preheating in an inert gas is also an effective means to prevent deterioration such as oxidation due to preheating. In addition, the preheating has the effect of preventing the ceramic outer layer molded body 3a from cracking due to thermal shock caused by casting, and from cracking due to the difference in shrinkage between the two after casting.

Regarding the mold rotation speed during centrifugal horn casting, GNl
The larger l and the higher the casting temperature promote penetration. Generally, GNII is around G20 to G200, but of course G
A value of 200 or more is also good because it increases penetration.

The molten metal for casting can be made of ordinary cast iron because the sleeve surface layer (first outer layer) is a dense ceramic layer and metal is not used directly, and from the viewpoint of strength and toughness, ductile cast iron, high-grade cast iron, You can choose cast steel, etc. High-grade cast iron is superior in terms of permeability. Of course, other ferrous or non-ferrous materials can also be used.

The amount of casting is sufficient to fill the pores of the second outer layer and form the inner layer, and of course the finishing allowance for the inner layer is taken into account.

By casting as described above, the metal material impregnated in the second outer layer portion and the metal inner layer become metallurgically continuous.

In addition, a material with good permeability, such as the above-mentioned high-grade cast iron, is first used as a second material.
The outer layer is impregnated or a little extra is cast, and then a strong material such as adamite, etc. is injected into the inner layer.
If graphite cast steel or the like is cast, easy penetration and mechanical strength can be easily achieved, and the inner metal layer and the impregnated metal material are metallurgically continuous.

Next, regarding the dimensional relationship of the sleeve according to the present invention, in the present invention, the outer diameter/ceramic outer layer thickness is limited to 8.0 and the ceramic outer layer thickness/metal inner layer thickness>1.5. By doing so, it is possible to suppress cracks caused by thermal expansion and contraction of the ceramic outer layer. The coefficient of thermal expansion of ceramics is 4 Xl0
-' 1 /'The coefficient of thermal expansion of C metal is approximately 12X10"'
1/'C, and the expansion of the ceramic during casting and impregnation with molten metal from the inner surface of the ceramic is approximately 1 Xl0-" (0
, 1%), but for ceramics with small plastic deformation and low thermal shock resistance, great care must be taken to prevent cracking during rapid heating. The same applies to the shrinkage process during solidification and cooling after impregnating the molten metal.

One way to do this is to make the thickness of the ceramic layer sufficiently larger than the metal layer pressure and at the same time increase the thickness of the ceramic layer relative to the outer diameter, thereby reducing the stress generated in the ceramic.

That is, when the outer diameter/ceramic thickness is greater than 8.0, the stress acting on the ceramic cross section increases, causing the problem of cracking.

Further, when the ceramic thickness/metal layer thickness is 1.5, the generated thermal stress becomes large, leading to the problem of cracking.

That is, consideration is given to safety against thermal expansion and contraction of the ceramic outer layer itself, and safety against the strong bonding between the ceramic outer layer and the metal inner layer, which has a significantly different coefficient of expansion.

The ceramic-metal composite sleeve has been described above, but as already mentioned, the present invention is to fix a plurality of the sleeves to the roller shaft by fixing means such as shrink fitting to form a hot runtable roller. Since it has a ceramic outer layer and the short sleeves are arranged at intervals, it has a small unit weight and requires less driving energy.

Next, specific examples of the present invention will be shown.

The manufactured product is a hot run table roller with a body diameter of 310φ and a body length of 18001 (ms), and a ceramic-metal composite sleeve with an outer diameter of 310φ, an inner diameter of 200φ, and an axial length of 2001<**> is made of 535C material of 200φ. Shrink-fitted onto the roller shaft.

fl) Molded body for ceramic outer layer Outer diameter 310 φ, inner diameter 230 φ, wall thickness 40t, length 2
A 50 J (mm) A e 203 molded body was used. The porosity of the molded body gradually increases from 3 to 50% from the surface to the inner surface.

(2) Casting A I! A 2 oz molded body was set on the inner surface of a centrifugal casting mold, and then the molded body was preheated. (800°C
) The above mold was rotated at 080°C, and in that state, 30kg of molten cast iron of the following table was impregnated into the second outer layer and the wall thickness was 20°C.
(equivalent to 1 m of metal inner layer molding) was cast at 1300°C.

-1% The balance is essentially Fe.

(3) Post-casting treatment After solidifying the metal inner layer, remove the sleeve from the mold and
The agricultural layer was cut.

(4) Shrink fit After cutting the inner surface of the above sleeve, the outer diameter is 200 φ and is 53 mm.
Four rollers were shrink fit onto a 5C roller shaft at a shrink fit ratio of 6/10000.

(5) Investigation Results The roller was disassembled and the cross section of the sleeve was investigated. As a result, the bond between the ceramic outer layer and the metal inner layer was good, and the metal impregnation state in the second outer layer of the ceramic was also substantial.

<Effects of the Invention> As described above, the hot run table roller of the present invention has excellent corrosion resistance and wear resistance because it has the first outer layer portion of the dense ceramic layer, and therefore has excellent fjt corrosion and wear resistance. In addition, it has excellent heat resistance and heat insulation properties, and has high resistance to thermal shock.Furthermore, the second outer layer of the ceramic outer layer is impregnated with metal to improve strength and toughness. , the diameter and thickness of the outer ceramic layer and the thickness of the inner metal layer are designed to ensure safety against thermal expansion and contraction, and by arranging short sleeves at intervals, weight is reduced and savings are achieved. This roller has a large energy effect and is extremely excellent as a roller used in the cooling zone of a hot run table, but it can also be used in other sectors, such as a slab transport roller before finish rolling, and the industrial value of the present invention is enormous. It is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of a hot runtable roller of the present invention, and FIG. 2 is a schematic sectional view showing a method for manufacturing a ceramic-metal composite sleeve related to the hot runtable roller of the present invention. . DESCRIPTION OF SYMBOLS 1...Hot runtable roller, 2...Ceramics-metal composite sleeve, 3...Ceramics outer layer,
3a... Ceramic outer layer molded body, 4... First outer layer part, 5... Second outer layer part, 6... Metal inner layer, 7...
・Roller axis. Patent applicant Kubota Iron Works Co., Ltd. Agent Patent attorney Yasu 1) Toshio, 1'...-□, J-Pami

Claims (1)

[Claims] (1) A sleeve consisting of a ceramic outer layer and a metal inner layer, wherein the ceramic outer layer is composed of a dense first outer layer portion and a second outer layer portion whose pores are impregnated with metal; The metal material impregnated with is metallurgically continuous with the metal inner layer, and has an outer diameter/ceramic outer layer thickness <8.0, ceramic outer layer thickness/metal inner layer thickness>
1. A hot runtable roller comprising a plurality of ceramic-metal composite sleeves that satisfy the condition 1.5 and are fixed to a roller shaft at intervals.