JPH02129315A - Roll for conveying stainless steel - Google Patents

Abstract

PURPOSE:To convey a stainless steel plate in a high temp. treatment furnace without getting any flaw by fitting to a rotating shaft while laminating forming body composed of inorganic fiber and inorganic filling material and the specific metal plate as doughnut-like as a roll for conveying the stainless steel plate in the high temp. treatment furnace. CONSTITUTION:As the conveying roll used at the time of heat-treating the stainless steel plate while continuously passing through a heating furnace, the doughnut-like forming plate 3 formed so that bulk density comes to 1.0-1.6g/cm<3> by using organic binder of modified acrylic ester, etc., in mixed material of the inorganic fiber of alumina fiber, etc., and the inorganic filling material of alumina powder, etc., and the doughnut-like metal plate 4 having <=1mm thickness of mild steel, etc., softer than the stainless steel, are laminated on outer circumference of the water cooling type metal shaft 1 and after fastening with a metal-made collar 2, the collar 2 is welded 5 to the metal shaft 1. The stainless steel can be conveyed in the high temp. treatment furnace without getting any flaw.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a conveyor roll used in a heat treatment line (annealing line or annealing/bicking line) that continuously heats high-temperature stainless steel plates, etc. Among these, it particularly relates to conveying rolls used in heat treatment furnaces.

(Prior Art and its Problems) A heat treatment line that continuously heat-treats stainless steel plates and the like has a large number of rolls arranged perpendicular to the direction of movement of the steel plates for loading and unloading the sheets.

By the way, among the above-mentioned rolls, rolls that come into contact with a steel plate in a high temperature state are required to have heat resistance, abrasion resistance, smoothness, non-adherence to the steel plate, and non-face-to-face attack resistance against the steel plate. Taking advantage of the properties of natural asbestos fibers, the rolls are made by forming asbestos fibers into sheets using a rubber binder, cutting these sheets into donut shapes, and then compressing and laminating them onto a metal shaft. It was used as an asbestos day scroll with a surface finish.

However, asbestos fibers are natural magnesium silicate mineral fibers, and have large variations in fiber length, fiber diameter, chemical composition, etc., and contain water of crystallization, so they cannot be heated to 1000°C.
When used in a high temperature range exceeding
As a result of volumetric contraction due to variations in water and separation of crystallized water, cracks occur on the roll surface, and these cracks can damage the surface of the steel plate being conveyed, and the rack expands during use, causing the roll to crack. There was a problem that the metal shaft would fall off.

Furthermore, asbestos fibers have a typical composition of Si0. is 43 wL%, MgO is 50 wt%, and F as an impurity.
Contains 5 to 6 wt% of compounds such as e201, Cab, Na, ○, and K t O, so at high temperatures, scale (
FezO:+, Fe30a, F e O, Cr t03
etc.) reacts with any one or more of the above-mentioned Fe, O, CaO, Na, 0, K, 0, etc., and adheres to the surface of the asbestos roll, while at the same time reducing the load of the stainless steel strip being conveyed. This will cause it to bite into the surface of the asbestos roll.

Once scale has bitten into the surface of the asbestos roll, new scale that is generated on the surface of the continuously conveyed stainless steel strip will adhere to the bitten scale and form a two-layer structure, and at the same time it will be conveyed. It digs into the asbestos roll surface under the load of the stainless steel strip.

The phenomenon in which scale repeatedly develops in layers is generally called r.
The thickness of the scale layer is about 15 μm, and the layered build amplifier may have a diameter of 0.1 to 1 mm and a length of several mm to 15 mm.

When the build-up grows to a certain size, the build-up stops growing inside the roll due to the internal pressure of the roll, and conversely, the internal pressure causes the build-up to protrude onto the roll surface. The above phenomenon is generally referred to as ``big amp'', and when a ``big amp'' occurs, the surface of the stainless steel strip being conveyed will be indented and scratched, resulting in product defects.

Conventionally, for the pressing defect caused by the pink-up,
The basic countermeasures have not yet been resolved, and as a countermeasure, we have empirically determined that the bulk density of the asbestos roll is appropriately adjusted depending on the material, thickness, etc. of the stainless steel strip to be transported, and that the pick amplifier is・Use the strip so that it wears out. That is, a method is adopted in which the big up is removed at the same time as self-wear.

However, if the bulk density is adjusted by the method of preventing pick-up due to self-wear, the strength deteriorates, and falling off occurs during use, making it difficult to achieve both self-wear and strength.

In addition, since asbestos is a natural mineral, its quality (mainly chemical composition) is uneven, and after roll forming, impurities such as Fez○s, Cab, NagOlK, and 0 were present in a high concentration on a part of the surface. In some cases, the build amplifier formation is picked up faster than the amount of self-wear of the roll, which may result in scratches on the product.

That is, there is a drawback that long life and stable operation cannot be expected.

Furthermore, since conventional ashesto day scrolls use asbestos fibers, asbestos fibers are scattered not only from the roll manufacturing process but also from the equipment used, posing a risk of health problems.

In other words, in Japan, the International Cancer Law was signed in 1972, and domestically, the handling of asbestos has been regulated by various ministerial ordinances, but from April 1, 1970, [
Implemented the Regulations for Prevention of Hazards Due to Specified Chemical Substances, and
On March 30, 2017, the Labor Standards Act Enforcement Regulations were partially amended. Dermatoma J is designated.

This ministerial ordinance has brought the issue of asbestos pollution into the spotlight in our country as well.

In contrast, instead of asbestos and day scrolls, sheets are formed using inorganic fibers such as silica and alumina fibers, which are artificial heat-resistant fibers, inorganic fillers, and inorganic and organic binders added as necessary. A conveyor roll has been proposed in which materials are compressed and laminated onto a metal shaft and the surface is finished. The transport roll uses artificial heat-resistant fibers, so there is less variation in fiber length and fiber diameter than asbestos, and the chemical composition is extremely stable with very few impurities, and does not contain crystal water. Therefore, even when used at high temperatures exceeding 1000°C, the roll has little shrinkage and can be operated stably.

However, since inorganic fibers such as silica/alumina fibers are amorphous, they undergo mullite recrystallization at temperatures around 980° C., causing slight thermal contraction.

Therefore, in a heat treatment line for stainless steel sheets, the conveying roll is water-cooled in places with relatively low temperature conditions, such as the outlet and inlet sides of a heat treatment furnace, or the rolls between the furnaces of a split heat treatment furnace. However, if the ambient temperature is 1.
The furnace roll used in the soaking zone or heating zone of the heat treatment furnace, which reaches around 200'C, has a metal shaft that is water-cooled, but the temperature of the roll surface is almost equal to the ambient temperature. , fine racks may occur on the roll surface.

Since the width of the fine rack is very small, the crank itself will not leave any scratches on the surface of the stainless steel plate to which it is transported, but like asbestos day scrolls, the fine rack will roll during use. There was a problem in that the roll gradually expanded inward and reached the metal shaft, causing the roll to fall off the metal shaft and become unusable.

In addition, regarding the wear rate of day scrolls made with conventional conveyor rolls using artificial heat-resistant fibers and inorganic fillers, the bulk density of the day scroll is inversely proportional to the wear rate, so the optimum wear rate depends on the bulk density. However, due to the lack of load capacity, it would fall off, making it difficult to withstand long-term use.

That is, a stainless steel transport roll that has an appropriate wear rate, leaves no scratches on the transported object, and can sufficiently withstand the load of the transported object has not yet been known.

(Means and effects for solving the problems) The present invention aims to eliminate and solve the drawbacks of the above-mentioned prior art, and as a means for achieving this purpose, the stainless steel conveyor described in the claims is It provides rolls for use.

That is, the present invention provides a stainless steel conveying roll in which a large number of doughnut-shaped molded plates mainly made of anon-aqueous fibers and inorganic fillers are laminated on a metal shaft, wherein the assembled bulk density of the molded plates is 1. 0 to 1.6 g/cd, and a donut-shaped metal plate is sandwiched between arbitrary layers of the molded plate.''

Specifically, the stainless steel conveying roll of the present invention focuses on the particle size and content of the inorganic filler, and selectively uses the inorganic filler to achieve an appropriate wear rate, and also has a metal plate sandwiched therein. This added strength. This makes it possible to share appropriate self-wear and strength for long-term use without damaging the transported objects.

The doughnut-shaped molded plate of the present invention mainly made of inorganic fibers and an inorganic filler is made of inorganic fibers, an organic binder, and an inorganic binder added as necessary.

Next, the present invention will be explained in detail.

The assembled bulk density of the molded plate in the stainless steel conveying roll of the present invention is 1. It is desirable that it is 0 to 1.6 g/cm. The reason for this is that if it is smaller than 1.0g/c++1, the assembly strength as a molded plate will deteriorate, making it difficult to use it as a molded plate for day scrolls, and the strength can also be maintained by sandwiching metal plates, which will be described later. It is difficult to handle and cannot withstand long-term use. On the other hand, if it is larger than 1.6 g/cd, it will become too dense and will not be able to fully exhibit its own abrasion, and will also lose its compressive reducing power during use, which will likely cause it to fall off.

The stainless steel transport roll of the present invention requires a donut-shaped metal plate sandwiched between the eyebrows of the laminated molded plates. The reason for this is that the metal plate sandwiched between arbitrary layers of the molded plate prevents strength deterioration due to a decrease in the density of the molded plate, and the water cooling effect of the metal shaft is not only applied near the metal shaft, but also near the surface layer of the day scroll. Even in the soaking zone and heating zone of a heat treatment furnace where the ambient temperature reaches around 1200°C, it is possible to prevent the occurrence of cranks on the roll surface and falling off from the metal shaft, resulting in extremely durable rolls. This is because it has excellent effects.

According to the present invention, as the inorganic fiber, artificial heat-resistant fibers such as silica/alumina fiber, crystalline alumina fiber, zirconia fiber, silicon nitride fiber, etc. can be used, but the compressive strength when fitted to the metal shaft is Silica-alumina fibers are more desirable because of their strength and low cost.

According to the present invention, the inorganic filler includes A1.03,
ZrJ, Si, N4.5iAION, ZrBz, 3A
One or more of h(h.2SiO2, etc.) can be used, but among these, A1.0. is desirable.

Further, according to the present invention, the content of the inorganic filler is 60 wt%.
Less than is desirable. The reason is that the blended amount of inorganic filler is 60%.
If it exceeds wt%, the proportion of inorganic fibers decreases, making it impossible to withstand the load of the conveyed object.The reason why it is desirable that at least two types of inorganic fillers having different average particle sizes are blended in particle size. In order to obtain the desired density and strength, it is difficult to control the particle size distribution in a fine particle size range by classification etc. with only one type having a continuous particle size distribution. It is good to control the density by controlling the particle size and average particle size by blending. Of course, if the particle size distributions and average particle diameters of the two or more types are similar and have a continuous particle size distribution with a distribution as a result of blending, it cannot be said that particle size blending is performed and there is no effect. Preferably, those having a large average particle size are at least twice as large as those having a small average particle size, and each particle size distribution is also sharp.However, those having a sharp particle size distribution are relatively expensive. There are many.

An example of a case where two types of inorganic fillers are blended in particle size will be specifically explained for use in the roll of the present invention.

The inorganic filler used has an average particle size of 1 to 5 μm and 50 to 50 μm.
It is desirable to mix two types of particles with a particle size of 60 μm.The reason is that when particles with an average particle size of less than 1 μm are mixed, they become close packed, making it impossible to reduce the density of the roll and moderately increasing the degree of wear. Things become difficult. Furthermore, if particles with an average particle size larger than 60 μm are used, the shape of the particles may be transferred to the conveyed object, causing scratches.

Further, it is desirable that the blending ratio of the two types is such that particles having an average particle diameter of 1 to 5 μm account for 50 to 80 wL% of the inorganic filling amount. The reason for this is that particles of 1 to 5 μm alone will significantly reduce the wear rate of the roll, and the build-up generated on the roll surface cannot be removed while being worn away. Furthermore, if only particles of 50 to 60 μm are used, the wear rate will be extremely high and the roll life will be extremely short. Even more preferably, for those with an average particle diameter of 1 to 5 μm, the content of particles of 1 μm or less is less than 10 wt%, and for those with an average particle diameter of 50 to 60 μm, the content of particles of 20 μm or less is less than 5 wt%. .

According to the present invention, as the inorganic binder, inorganic coroitia represented by coroital silicate, clay minerals such as wooden tablet clay, and sintering aids such as frit can be used. However, if the use conditions are such that a relatively light strength is sufficient to withstand use in an atmosphere of 1200°C, the inorganic binder may not be used.

Further, as the organic binder, emulsion latexes such as NBR, SBR, and acrylic acid esters, paper strength enhancers typified by polyacrylamide, and the like can be used. Among these, it is preferable to use a combination of modified acrylic ester emulsion latex to provide wet strength when producing the doughnut-shaped molded plate, and polyacrylamide to provide strength after drying. Effective.

According to the present invention, the material of the metal plate needs to be a metal softer than the stainless steel being transported. The reason for this is that if the metal plate is exposed on the roll surface, it will not only cause scratches on the stainless steel plate being conveyed, but also cause the metal plate itself to become an oxide, and on top of this oxide, the oxides generated on the stainless steel surface will This causes build-up and build-up, which causes indentation scratches on the surface of the stainless steel sheet being transported.However, by making the material of the metal sheet a softer metal than the stainless steel being transported, the metal sheet can be formed on the surface of the roll. Even if the metal is exposed to water, the metal is softer than stainless steel, so it can be transported without causing self-wear and scratches on the stainless steel surface.

Additionally, even if metal oxides are generated on the surface due to oxidation of the metal plate itself, the softness of the metal acts as a buffer, making it possible to transport the stainless steel plate without indentation scratches on the surface. It is.

Furthermore, since the metal plate can be exposed to the surface of the day scroll, the cooling effect of the metal shaft can be made more effective.

According to the present invention, the thickness of the metal plate needs to be thinner than III+. The reason why the thickness of the metal plate is made thinner than 1 mm is that if the thickness is more than 1 mm, the weight of the roll will increase significantly, which will interfere with idle rotation, and also because the metal plate is sandwiched between layers of a doughnut-shaped molded plate made of inorganic fibers. When compressed and fitted onto a metal shaft, a significant difference occurs in the bulk density of the doughnut-shaped formed plate made of inorganic fibers between the roll surface layer without the metal plate and the inside of the roll where the metal plate is adjacent; This is because a significant difference in strength occurs at the interface at the outer periphery of the metal plate.

Note that the spacing between the narrowly arranged metal plates does not necessarily have to be equal, and the spacing may be changed as appropriate depending on the roll surface temperature distribution when the roll is used in an actual furnace. However, according to the present invention, the cooling effect can be sufficiently exhibited, and considering that the weight of the roll itself is increased, the distance between the metal plates that are narrowly arranged is 15 +
A value below am is appropriate. Particularly in high-temperature areas, it is preferable that the interval be smaller than 511 Ill.

Further, the metal plate used in the present invention may be (mild steel, brass, copper plate, etc.), but mild steel is more preferable from the viewpoint of heat resistance and cost.

The stainless steel transport roll according to the present invention has the following effects.

First of all, the area from the surface layer of the conveyor roll to the part where the metal plate is fitted will not react or fuse with the stainless steel plate or stainless steel oxides being conveyed under hot conditions around 1200°C. Because it has a suitable hardness, it will not scratch the stainless steel plate being transported. Furthermore, at least two types of inorganic fillers having different average particle diameters are blended, and the assembled bulk density of the molded plate is 1.0 to 1.
By setting an appropriate roll wear rate to 6g/C+6, the stainless steel plate will not be scratched and will have as long a life as possible.
It is possible to prevent indentation scratches on the stainless steel plate that is the object to be transported by the conveyor (or pickup). In addition, the metal plate sandwiched inside the conveyor roll reinforces the molded plate, and the water cooling effect of the metal shaft is effectively exerted to the vicinity of the roll surface, thereby preventing cracks that occur on the roll surface due to heat shrinkage. It is possible to prevent this.

The present invention will be explained by examples.

(Example 1) Commercially available silica/alumina fiber. The average particle size of alumina is 1.1 μm with 60 wt% of Ivar (trade name: Ibi Wool Bulk) and commercially available fine-grained low soda alumina (Showa Denko ■) (contains 10 wt% of particle size of 5 μm or more, less than 5% of particle size of 1 μm or less).
60wt%, alumina average particle size 55μm (containing 30wL% of 60μm or more, less than 5% of 20μm or less)
Alumina grains with a weight of 32 wt. After adding 1.5% by weight of the reinforcing agent, it was flocculated using sulfuric acid clay and a polyacrylamide polymer flocculant, and then cut to a width of 30 mm using an end machine.
A continuous wet sheet with a thickness of 181 mm and a thickness of 0 mm was made.

Then, the bulk density of the wet sheet after drying is 0.8 g.
/c4, dehydrated and pressed to a thickness of 3mm, inner diameter 1501111, outer diameter 265 in wet state
A molded plate for a day scroll was produced by punching out a donut shape of mm and drying it.

Next, a commercially available mild steel plate (thickness 0.29 mm) with an inner diameter of 150
゜05+m, punched into a donut shape with an outer diameter of 265mm,
Created a metal plate.

Next, three of the molded plates were fitted onto a metal shaft with an outer diameter of 150cm and a wall thickness of 211IIl, which had a metal collar welded to one side, and then one metal plate was fitted.This operation was repeated in sequence. After that, a metal collar was fitted and compression pressed, and then the metal collar was welded, and the outer diameter was 265 II 11 and the roll action surface length was 1800.
An, the roll had a bulk density of 1.4 g/cJ in the molded plate portion. Also, the spacing between the metal plates is approximately 4. It was hm. Furthermore,
The outer diameter of this roll was lathed to an outer diameter of 250 mm using a metal lathe to create a day scroll for a stainless steel catenary furnace. FIG. 1 shows an outline of the day scroll.

Further, the wear rate of the roll was measured by the method shown in FIG. As a result, the wear rate was 18.8 wt%. The wear test for measuring the wear rate was carried out using the testing machine shown in Fig. 2, using a roll baked at 800°C for 2 hours, and using a rotor plate (7) (sandpaper on a steel plate) rotating a forming roll (6). The abrasion weight loss rate of the forming roll was measured when the rotor plate was rotated at a rotational speed of 72r, p, m while applying a constant load (9) on the formed roll.

When the day scroll was used as a conveyor roll in a catenary furnace (ambient temperature 1200°C), it was approx.
00) When the stainless steel plate (SO5304) was heat treated, the outer diameter of the roll was about 7IIITl Pi! Despite wear, no cracks were observed on the roll surface, and no indentation flaws due to build-up (pink-up) were observed.

(Example 2) Same as the example, except that the alumina particles as an inorganic filler were used with an average particle size of 3. OtIm (contains 1 wt% ungrooved with a particle size of 5 μm or more, less than 10% of 1 μm or less) is 50 wt%, alumina average particle size is 55 μm (30 w% of alumina is 60 μm or more, 20 μm)
A roll having a bulk density of 1.5 g/cd in the molded plate portion was prepared by blending two types of 50 wt % f) containing less than 5% m or less. As a result of measuring the wear rate in the same manner as in Example 1, the wear rate was 33 wt%.

As in Example 1, when the day scroll was used as a conveyor roll in a catenary furnace (ambient temperature 1200°C), approximately 6000 tons of stainless steel plate (SUS
304), the outer diameter of the roll was 15111 mm.
Although the roll was worn to an extent of 11%, no cracks were observed on the roll surface, and no indentation flaws due to build up (pink-up) were observed.

(Comparative Example 1) Same as Example 1, except that the alumina particles as an inorganic filler had an average particle size of 3.0 μm (particle size of 5 μm or more and less than 1 wt%, 18 m or less and less than 10%) was 20 wt%, and alumina average Particle size 55 μm (60 μm or more 30 wt%, 20 μm
Contains less than 5%) at 80wt%,
A roll having a bulk density of 0.8 g/cd in the molded plate portion was created. As a result of measuring the wear rate in the same manner as in Example 1, the wear rate was 45 wL%.

As in Example 1, when the day scroll was used as a conveyor roll in a catenary furnace (ambient temperature 1200°C), a stainless steel plate (approximately 3000°C) was used.
304), the outer diameter of the roll was 30 mm.
There was some wear and cracks were observed on the roll surface.

(Comparative Example 2) Same as Example 1, except that 85 wt% of alumina particles with an average particle size of 3.0 μm (containing particle size of 5 μm or more and less than 1 wt%, and less than 10% of l/7m or less) were used as an inorganic filler. Average particle size 55 μm (60 μm or more 30 wt%, 20 μm
A roll having a bulk density of 2.0 g/cj in the molded plate portion was prepared by blending two types of 15 wt % of (containing less than 5% m or less). As a result of measuring the wear rate in the same manner as in Example 1, the wear rate was 7.5 wt%.

As in Example 1, when the day scroll was used as a conveyor roll in a catenary furnace (ambient temperature 1200'C), the stainless steel plate (SO5
304), the surface of the stainless steel plate being transported was left with scratches.

Note that the outer diameter of the roll was hardly worn.

(Comparative Example 3) Same as Example 2, but instead of the alumina average particle size of 55 μm (containing 30 wt% of 60 μm or more, less than 5% of 20 μm or less) used in Example 2, an average particle size of 75 μm (60 μm or less) was used.
80 wt% of μm or more, 0% of 20 μm or less)
The bulk density of the molded plate part is 0. 9g/co!
created a role.

As a result of measuring the wear rate in the same manner as in Example 1, the wear rate was 43w%.

When used in the same furnace as in the example, marks of indentations were left on the surface of the stainless steel plate being transported.

(Effects of the Invention) As described above, the stainless steel conveying roller according to the present invention has a disc plate in a non-asbestos day scroll conventionally used as an outer roll of a stainless steel catenary furnace and an inter-furnace roll of a split catenary furnace. By inserting a metal plate made of a material softer than stainless steel between the layers, the stainless steel plate being conveyed will not be damaged even when rolled in a furnace with a high ambient temperature, and there will be no cranking and there is no risk of it falling off the metal shaft. It is now possible to provide rolls with high durability without any scratches.

In addition, since no asbestos fibers are used, the production or use of the rolls is subject to the "Specified Chemical Substance Hazard Prevention Regulations."
It has become possible to provide a roller that is completely free from the risk of causing asbestos pollution as stipulated in .

[Brief explanation of the drawing]

FIG. 1 is a broken cross-sectional view of the roll of Example 1 of the present invention,
This is a schematic diagram of a metal plate fitted inside the roll. FIG. 2 is a perspective view of the abrasion tester used to measure the wear rate of the rolls. Explanation of symbols Water-cooled metal shaft 2. Metal color forming plate Metal plate Metal plate Welding part of metal collar to water-cooled metal shaft Roll support stand weight installation for testing Jig Load adjustment weight Figure 1 or above

Claims (1)

[Claims] In a stainless steel conveying roll in which a large number of doughnut-shaped molded plates mainly made of inorganic fibers and inorganic fillers are laminated on a metal shaft, the assembled bulk density of the molded plates is 1.0 to 1.0.
1.6 g/cm^3, and a donut-shaped metal plate is sandwiched between arbitrary layers of the molded plate.