JP2650774B2 - Roll for transporting high-temperature steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a roll for transporting high-temperature steel, and particularly to a proposal for a transport roll suitable as a roll installed in a heat treatment furnace for a stainless steel plate.

[Related Art] As a roll for transporting a high-temperature steel material, for example, a high-temperature stainless steel plate to be processed in a heat treatment line, a roll having a surface coated with a heat-resistant material is used.

By the way, such coated rolls for heat treatment furnaces, especially coated rolls for transport installed in a soaking zone where the temperature exceeds 1200 ° C., are because the material to be transported (stainless steel plate) is softened. It is important that even a slight change in the roll surface causes such a transport material (stainless steel plate) to have flaws easily, and therefore the surface condition is stable for a long period of time.

On the other hand, paying attention to the roll itself, the main body of the transport roll is used in a high-temperature atmosphere, so that the center of the roll is usually water-cooled. Therefore, the surface of the roll serving as the sheet passing surface is covered with a heat insulating material or the like, thereby preventing the temperature of the transport steel sheet from lowering. In addition, the covering material used for such a purpose needs to be a substance that is unlikely to be damaged as described above. For example, asbestos or silica / alumina fibers are typical coating materials.

Examples of the transporting covering roll as described above include those conventionally disclosed in JP-A-1-290712 and JP-A-1-301818. These conventional rolls are made by laminating a disc-shaped heat-resistant heat-insulating sheet around the roll axis in the axial direction to form a heat-insulating layer. By devising the structure of this heat-insulating layer, durability and build-up resistance are improved. This is to improve the characteristics.

[Problems to be solved by the invention]

However, the above-described conventional transport rolls have various problems as described below. That is, the coating layer of the heat-resistant heat-insulating member attached around the roll axis of the water-cooled roll is a doughnut-shaped one mainly composed of asbestos or heat-resistant inorganic fiber, and is fitted and laminated in the axial direction of the water-cooled roll, Further, it is formed by compressing and finishing to a predetermined outer diameter. However, the work of inserting such a donut-shaped sheet into a roll requires a great deal of labor and time. In addition, this conventional transport roll
According to the results used in an actual heat treatment furnace, the coating layer that forms the roll surface has a laminated structure of sheet-like materials, so the asbestos and inorganic fibers that are the coating components are severely deteriorated and hardened. A phenomenon of falling off from the roll was observed at some time, and there was a problem that the operation was stopped in a short time and the operation had to be stopped. Furthermore, in this conventional transport roll, the scale generated on the surface of the stainless steel plate adheres to the surface of the roll, and the scale attached to the roll surface damages the surface of the subsequent transport material (stainless steel plate). The problem that the evil effects of the build-up have not yet been solved remains.

Therefore, an object of the present invention is to form a transport roll coating layer easily, and the coating layer has high resistance to contamination and defects, and the roll surface properties are always stable for a long period of time. The purpose is to develop a transport roll that is difficult to build up.

[Means for solving the problem]

As a result of intensive studies to achieve the above-mentioned objects, the present inventors have found that the above-mentioned coating layer has been replaced with a conventional structure in which a sheet material mainly composed of inorganic fibers is laminated, It has been found that the application of the method can overcome the disadvantages of the prior art. That is, it has been found that the problem of the prior art can be solved by using a transporting roll having the surface of the roll sprayed with the following various spraying materials having the same effect as a coating layer.

As such a thermal spray coating layer, a cermet thermal spray coating layer having excellent heat resistance and heat insulating properties and having machinability is preferable. As such a cermet thermal spray coating layer, 4 to 10 wt.
Thermal spraying material composed of various heat-resistant alloys containing Ni, Cr, Fe, and Al, or a thermal sprayed material containing 15 to 30 wt% of calcined bentonite and the remainder composed of the same heat-resistant alloy is preferable. Layer thickness is 0.5-5mm
It can be said that it is preferable to make the layer thickness as follows.

 The details of the present invention will be described below.

The feature of the configuration of the stainless steel transfer (in-furnace) roll according to the present invention is that a cermet material having excellent heat resistance and heat insulation properties and excellent machinability is provided outside a heat-resistant steel roll having a hollow water-cooled structure. To provide a thermal spray coating layer having excellent machinability.

The machinability as used herein means that the coated thermal spray coating has a property of being easily worn away by a contacting material (transport material). Therefore, when the thermal spray coating having such characteristics is applied to the outer peripheral surface of the transport roll, the following effects are exhibited. That is, the oxide (scale) generated on the surface of the stainless steel sheet to be conveyed,
The build-up phenomenon caused by the transfer to the roll surface is gradually reduced by the action of the gradually eroding coating surface. As a result, even if the stainless steel sheet in the softened state comes in Since there is no up, there is no phenomenon that a press flaw is generated.

As a cermet material having excellent heat resistance and heat insulating properties and having machinability as described above, the present inventors have found from various experimental results that cermet of BN and an alloy such as Ni, Cr, Fe or Al, or It has been found that the cermet of the calcined bentonite and the heat-resistant alloy is effective.

The cermet of BN and the heat-resistant alloy has a BN content of 4
The intended purpose is achieved at ~ 10 wt%. This BN content is 4w
If it is less than t%, the machinability is reduced, and it is difficult to remove the build-up generated. On the other hand, if the BN content exceeds 10% by weight, the rolls are frequently exchanged because wear occurs early.

Further, according to the study of the present inventors, it has been found that a material composed of calcined bentonite and the heat-resistant alloy is effective as the cermet material. In this cermet, it is effective that the content of the calcined bentonite is 15 to 30% by weight. The content of this calcined bentonite is
If the amount is less than 15%, the machinability deteriorates and it becomes difficult to remove build-up generated on the roll surface. On the other hand, if the content of the calcined bentonite exceeds 30 wt%, the abrasion proceeds early and the rolls must be replaced frequently,
It is uneconomical.

The heat-resistant alloy constituting the cermet is, for example, Ni-Cr-Fe-Al alloy, Ni-Cr-Al alloy, or Ni or
Other ferrous and non-ferrous heat-resistant alloys including Cr are used.

Next, the thickness of the cermet sprayed coating layer formed on the surface of the water-cooled hollow roll base material, because the roll body is water-cooled by the water introduced into the hollow shaft portion, the temperature of the stainless steel sheet to be conveyed The insulation effect must be increased so as not to lower it. For this purpose, the thickness of the coating layer must be at least 0.5 mm. Also, as this layer thickness increases, the heat insulating effect increases, but on the contrary, the adhesiveness is reduced and peeling may occur. Therefore, it is necessary to avoid coating to a thickness exceeding 5 mm. Therefore, the thickness of the thermal spray coating layer is preferably 0.5 to 5 mm.

(Operation)

The cermet sprayed coating layer according to the present invention configured as described above has the following effects.

Such a thermal spray coating layer has a high surface smoothness unlike the conventional laminated structure of a sheet-like material, and therefore, the contact state between the stainless steel plate and the roll surface during the passing of the sheet becomes soft and smooth conveyance becomes possible. . In addition, since it is a sprayed coating layer of cermet with machinability, it gradually wears out,
There is no risk of product defects due to build-up on the transported stainless steel plate. Moreover, in such a coating layer, even if the roll main body is water-cooled, the outermost surface temperature of the roll can be maintained at the furnace temperature, and the temperature of the stainless steel sheet on the sheet passing surface does not decrease. That is, in the case of the coating layer according to the present invention, even if build-up occurs, the self-cleaning action works due to the machinability of the coating layer, and it can be easily removed. It is possible to prevent.

〔Example〕

A transfer roll formed according to the present invention as shown in FIG. 1 was applied to a heat treatment furnace exclusively for stainless steel having a production capacity of 24,000 tons / month, and a life test was mainly performed. The results are summarized in Table 1.

As compared with the conventional asbestos-coated roll (No. 1), asbestos covering the surface dropped off when the production amount reached 6000 tons. Also, the transport roll (No. 2) provided with a coating layer of silica-alumina fibers was removed at that time because build-up occurred at the stage of processing 6000 tons and there was a concern about flaws on the stainless steel plate.

Among the cermets of BN and heat-resistant alloy, the transport roll (No. 3) with a BN content of 2 wt% builds up when it processes 10,000 tons, and has a BN content of 12 wt%.
% Roll (No. 4) was worn out at the stage of processing 20,000 tons and was removed on the way, but nevertheless, the life was significantly extended compared to the conventional transport roll.

In contrast, the BN content was 4 wt% (No. 7) and 10 wt% (N
The rolls of o.8) were able to achieve a significant life extension of 100,000 tons and 80,000 tons, respectively. Especially 10% BN content
When the thickness of the coating layer is 5 mm (No. 9),
A longer service life was achieved.

Similarly, for transport rolls coated with fired bentonite and a cermet made of heat-resistant alloy, the life of transport rolls with fired bentonite contents of 10 wt% (No. 5) and 40 wt% (No. 6) is Although the product slightly exceeded the product, the content of calcined bentonite was 15wt% (No.10), 30wt%
In (No.11), the service life was greatly extended.

〔The invention's effect〕

As described above, the high-temperature steel material transfer roll according to the present invention automatically builds up and disappears, and has a smoother surface property than that of the laminated material. It can be used while maintaining a stable surface state for a long time without being attached, and in the initial state. As a result, it is possible to simultaneously improve the quality of the stainless steel sheet and extend the life of the roll.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a roll according to an embodiment of the present invention, schematically showing that a cermet material having excellent heat resistance and machinability is spray-coated on the roll surface. I have. 1 roll body 2 spray coating layer 3 cooling water

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-141819 (JP, A) JP-A-61-174318 (JP, A) JP-B-53-35885 (JP, B2) JP-B-51- 47405 (JP, B2)

Claims (1)

(57) [Claims] 1. A roll having a heat-resistant heat-insulating material coated on the outer peripheral surface of a water-cooled hollow roll, wherein the heat-resistant heat-insulating material has a coating layer having a thickness of 0.5 to 5 mm and a BN content of 4 to 10 wt%. A single-layer thermal spray coating that is either a machinable BN cermet with a balance of heat-resistant alloy or a burnt bentonite cermet with a calcinable bentonite of 15 to 30 wt% and a balance of heat-resistant alloy A roll for transporting high-temperature steel, comprising a layer.