JPH0569155U - Roller bearing device in molten metal plating bath - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a bearing device for a roll in a molten metal plating bath, which is capable of prolonging the life of the bearing device and constantly plating a steel plate with a constant thickness. [Structure] A lower build-up layer 2a of a Co-based alloy is formed on the surface of the shaft portion 2 of the roll, and a Co-based alloy + Cr ₃ C ₂ is formed on top of this.
The upper buildup layer 2b is formed and the bearing device 1 in contact with the upper buildup layer 2b is made of ceramic such as Si ₃ N ₄ . [Effect] It is possible to significantly reduce the wear of the shaft portion of the roll and the bearing member, maintain the roll mounting accuracy before immersion for a long period after immersion in the plating bath, and prolong the service life of the bearing device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to, for example, a bearing device that rotatably supports a roll that is immersed and placed in a molten metal plating bath in a continuous hot-dip galvanized steel sheet manufacturing facility.

[0002]

[Prior Art]

 As is well known, hot-dip galvanized steel sheet represented by hot-dip galvanized steel sheet is a sink roll that is immersed and placed in a hot-dip galvanizing bath after the surface of the steel sheet is cleaned and activated. Then, it is manufactured by changing the traveling direction and pulling it up and controlling the amount of metal deposited on the surface of the steel sheet by a gas wiping method or the like so that the plating thickness on the steel sheet becomes a predetermined thickness.

Here, in a manufacturing facility for manufacturing this hot-dip galvanized steel sheet, a hot-dip metal sheet is fed into the hot-dip galvanizing bath 11, for example, as shown in FIG. A non-driving sink roll 13 for changing the traveling direction of 12 and a purpose of correcting the warp of the steel plate 12 that occurs when passing through the sink roll 13 and preventing the vibration of the steel plate 12 at the gas wiping nozzle 15. Thus, the drive support roll 14 is soaked and arranged.

By the way, conventionally, a bearing device for rotatably supporting the above-mentioned roll, which is immersed in a molten metal plating bath, is shown in plan view as shown in FIGS. 2 (a) and 2 (b). Has a structure in which a bearing member 16 made of heat-resistant steel or the like having an arcuate inner peripheral surface is held by a housing 17, and the shaft portion a of the roll A is supported by the arcuate portion 16a of the bearing member 16. ing.

The bearing device having the above structure is usually assembled before being immersed in the molten metal plating bath 11, and the shaft portion a of the roll A and the arcuate portion 16a of the bearing member 16 are in contact with each other. Determined at the time of assembly.

In FIG. 2A, the radius R of the arcuate portion 16a of the bearing member 16 is set to be larger than the radius r of the shaft portion a of the roll A. Even if the shaft portion a of the roll A and the bearing member 16 supporting the roll A are displaced due to thermal deformation in the molten metal plating bath, the roll A can be rotatably supported. It is because of consideration.

[0007]

[Problems to be solved by the device]

 However, in the bearing device according to the above-mentioned configuration, in the hot-dip molten metal plating bath, due to thermal deformation, the contact position between the shaft portion a of the roll A and the bearing member 16 is “shifted” as compared with that before the immersion. Is generated, the roll A can rotate, but a slight deviation occurs in the relative positional relationship between the sink roll 13 and the support roll 14 having the arrangement relationship shown in FIG. Even if the roll A is rotated in this state, good rotation cannot be obtained, and the steel sheet cannot be run in the bath in a stable state.

Further, as shown in FIG. 2, the gap due to the difference in diameter between the shaft portion a of the roll A and the bearing member 16 is large, and the shaft portion a of the roll A in the molten metal plating bath is large. Since the bearing member 16 cannot cope with thermal deformation, the surface pressure generated between the shaft part a of the roll A and the bearing member 16 becomes high, and further, it is used in a corrosive environment such as in a molten metal plating bath. However, significant wear occurred and the life of the bearing itself was short.

As described above, in the conventional sliding bearing structure, it is difficult to maintain the mounting accuracy of the shaft portion a of the roll A and the bearing member 16 before and after the bearing device is immersed in the molten metal plating bath. Since the wear between the shaft part a of the roll A and the bearing member 16 is remarkable, a slight deviation occurs in the relative positional relationship with other rolls, and the steel plate 12 shown in FIG. 3 is in a very unstable state. When the hot-dip galvanized steel sheet is manufactured in such a state, the plating thickness of the product becomes non-uniform and the commercial value is significantly reduced.

Further, since the frictional resistance between the shaft portion a of the roll A and the arcuate portion 16a of the bearing member 16 becomes large, the bearing member 16 is easily worn, and therefore the life of the bearing itself is short and the replacement cycle is long. Since it becomes quicker, there is an inconvenience that the labor required for replacing the bearing device significantly reduces the production efficiency of the plated steel sheet.

Further, in order to solve the above-mentioned inconvenience, for example, in Japanese Utility Model Laid-Open No. 61-90852, a rolling bearing made of a ceramic material is proposed, but even if the bearing itself is made of a ceramic material. However, since the housing that supports this is made of metal, it is extremely fragile against cracking problems due to the difference in coefficient of thermal expansion and overload caused by momentary concentration, and the structure is complicated. There is.

The present invention has been made in view of the above problems, and an object thereof is to provide a bearing device for a roll in a molten metal plating bath that can be used in a stable state for a long period of time.

[0013]

[Means for Solving the Problems]

 In order to achieve the above object, in the present invention, in a bearing device for rotatably supporting a roll arranged in a molten metal plating bath, the surface of the shaft portion of the roll is made of a carbide of a Co-based alloy as a base. In addition to forming the heap layer, the bearing member that is in contact with the surface of the shaft of the roll is made of ceramic.

In the above structure, preferably, a build-up layer of a carbide containing a Co-based alloy as a base is formed on the surface of the shaft of the roll by a powder plasma welding method. A Co-based alloy containing Cr ₃ C ₂ or W ₂ C is used, and the ceramic constituting the bearing member is a ceramic containing Si ₃ N ₄ as a main component.

Further, in the above configuration, the build-up layer formed on the surface of the shaft portion of the roll is composed of one or two build-up layers, and in the case of one layer, as described above, Carbide based on a Co base alloy is overlaid, and in the case of two layers, the lower overlay layer is a Co base alloy with a thickness of 1 to 5 mm and the upper overlay layer is a Co base alloy with a thickness of 2 to 10 mm. Of Cr ₃ C ₂ or W ₂ C.

[0016]

[Action]

 According to the bearing device for the roll in the molten metal plating bath according to the present invention, since the build-up layer of carbide based on Co-based alloy is formed on the surface of the roll shaft, and the bearing member is made of ceramic, The wear of the shaft surface and bearing member side can be significantly reduced, so that the life of the bearing device can be extended, and the mounting accuracy of the shaft and the bearing member of the roll does not decrease, so the steel plate Can be run stably, and the plating thickness of the product can be made uniform.

Further, since the build-up layer of carbide based on Co-based alloy formed on the shaft surface of the roll is applied by the powder plasma welding method, the build-up layer and the roll shaft surface are Since the adhesion is high and the Co-based alloy is used as a base, the carbide can be uniformly dispersed in the overlay layer, and the hardness of the overlay layer can be made uniform.

If the buildup layer applied to the surface of the roll shaft is divided into upper and lower layers and the upper buildup layer is formed via the lower buildup layer, the surface of the roll shaft and the upper buildup layer are formed. Since the layers can be blocked and the difference in thermal expansion between the roll shaft and the upper buildup layer can be absorbed, the hardness of the roll shaft surface can be maintained and cracks can be generated. It is possible to maintain the mounting accuracy of the bearing device before and after immersion in the molten metal plating bath.

When the build-up layer has two layers, the reason why the thickness of the lower build-up is preferably 1 to 5 mm is that when the thickness is less than 1 mm, the roll shaft and the upper meat formed on the surface of the shaft are This is because it is not sufficient to shield from the build-up layer, and the difference in thermal expansion between the two cannot be absorbed, and the effect of the lower build-up layer does not change even if it exceeds 5 mm.

Further, the reason why the thickness of the upper buildup layer is desirably set to 2 to 10 mm is that it is unsatisfactory for long-term use when it is less than 2 mm, and if it exceeds 10 mm, cracks may occur in the buildup layer. This is because it easily occurs, and suitable wear resistance is imparted within the range of 2 to 10 mm.

Further, desirably, when chromium carbide is used as the carbide to be built up on the surface of the shaft of the roll, it can be dissolved in the matrix and uniformly dispersed, and Cr ₃ C ₂ can be contained in other materials. Compared to carbides (Cr ₇ C ₃ , Cr ₂₃ C _6, etc.), it has a large carbon content and can be dispersed in the built-up layer in a large amount.

When tungsten carbide (W ₂ C) is used as the upper buildup layer, it is present in the buildup layer in an undissolved state. In particular, W ₂ C has a higher hardness than WC, It has excellent wear resistance.

Further, when a build-up layer of a Co-based alloy Cr ₃ C ₂ is formed on the surface of the shaft of the roll and the bearing member is made of a ceramic containing Si ₃ N ₄ as a main component, those Due to the difference in hardness, the surface of the shaft of the roll is worn and the bearing member is not worn, so that the amount of wear on the surface of the shaft of the roll can be reduced to one-tenth or less of the conventional amount.

Further, when a W ₂ C buildup layer of a Co-based alloy is formed on the surface of the shaft of the roll and the bearing member is made of ceramics containing Si ₃ N ₄ as a main component, the surface of the shaft of the roll is Although the bearing member also wears, the amount of wear of the bearing as a whole can be reduced to 1/10 or less of the conventional amount.

[0025]

【Example】

 Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a sectional view of a bearing device for a roll in a molten metal plating bath according to the present invention. Fig. 1 (a) shows a cross section in the axial direction of the roll, and Fig. 1 (b) shows Fig. 1 (a). 2 is a cross-sectional view taken along line XX of FIG. Needless to say, the structure of the bearing device having the above-described configuration is applied to the bearing device for supporting the sink roll and the support roll immersed in the molten metal plating bath shown in FIG.

In the figure, 1 is a bearing member, 2 is a shaft portion of a roll, and the shaft portion 2 of the roll has a lower buildup layer 2 a formed of, for example, a Co-based alloy and a Co-based alloy on the surface of the shaft 2. The upper buildup layer 2b made of alloy + Cr ₃ C ₂ is sequentially formed, and the bearing member 1 is made of, for example, ceramic containing Si ₃ N ₄ as a main component.

The components of the above Co-based alloy were Cr = 27%, C = 1%, Co = residual, and the mixing ratio of Cr ₃ C ₂ used in the upper buildup layer 2b was 50%.

Further, the radius of the bearing member 1 was 70 mm, the radius of the shaft portion 2 of the roll was 59.5 mm, and the contact length between them was 100 mm.

As a result of employing the bearing device having the above-mentioned configuration in a hot dip galvanized steel sheet manufacturing facility and continuously operating for 10 days, the amount of wear on the shaft portion of the roll was 0.6 mm, but the amount of wear on the bearing member side was Since the rolls rotate smoothly, it was possible to stably run the steel sheet in the plating bath and perform plating with a uniform thickness on the steel sheet surface.

Example 2 In Example 1 above, on the surface of the shaft portion 2 of the roll, for example, a lower buildup layer 2a made of a Co-based alloy and an upper buildup layer 2b made of a Co-based alloy + Cr ₃ C ₂ were used. An example of the case where the bearing member 1 is made of ceramics containing Si ₃ N ₄ as a main component has been described, but the lower buildup layer of the Co-based alloy and the Co-based alloy + W is formed on the shaft surface of the roll. _{As in} the case of Example 1, the bearing member 1 was made of a ceramic containing Si ₃ N ₄ as a main component by applying a ₂ C upper buildup layer.

The main components of the above Co-based alloy are Cr = 27%, C = 0.2%, Co = residual, and the mixing ratio of W ₂ C used in the upper buildup layer 2b is 40%. The half diameter of the bearing member, the radius of the roll shaft portion 2, and the contact length between the roll shaft portion 2 and the bearing member 1 were exactly the same as in Example 1.

As a result of adopting the bearing device having the above-mentioned configuration in a facility for manufacturing hot-dip galvanized steel sheet and continuously operating for 10 days, the amount of wear on the shaft portion of the roll was 0.2 mm and the amount of wear on the bearing member side was 0. The wear was 1 mm, which was extremely small, and did not hinder the smooth rotation of the roll.

In each of Examples 1 and 2 described above, the wear amount of the conventional bearing was one-tenth or less, and the condition of the wear surface was extremely smooth, and the streaks in the circumferential direction seen in the conventional bearing were observed. No wear was observed.Therefore, the steel strip to be plated using the hot-dip galvanized steel sheet manufacturing equipment that uses this bearing device should always have a uniform thickness without changing the bearing device. It became possible to plate with.

[0034]

[Effect of the device]

 As described above, according to the bearing device of the present invention, the wear of the roll shaft and the bearing member side can be significantly reduced, the life of the bearing device can be extended, and the mounting accuracy can be improved. Since it is extremely good, there is an effect that the steel sheet can be run in a stable state and a product having a uniform plating thickness can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a bearing device according to the present invention, in which FIG. 1 (a) shows a cross section perpendicular to the axial direction of a roll shaft portion, and FIG. ) Is a sectional view taken along line X-X.

FIG. 2 is a view showing a conventional bearing device, and FIG.
Is a front view, and FIG. 6B is a side view with a partial cross section.

FIG. 3 is a schematic diagram showing a facility for manufacturing a general hot-dip galvanized steel sheet.

[Explanation of symbols]

 1 Bearing member 2 Roll shaft 2a Lower buildup layer 2b Upper buildup layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomio Kondo 1850 Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Steel Works (72) Inventor Yoshihiro Tatsumi 1-9-1, Jokoji, Amagasaki, Hyogo Osaka Fuji Kogyo Within the corporation

Claims (1)

[Scope of utility model registration request] 1. A bearing device for rotatably supporting a roll immersed in a molten metal plating bath, wherein a build-up layer of carbide based on a Co-based alloy is formed on the surface of the shaft of the roll, and A bearing device for a roll in a molten metal plating bath, characterized in that a bearing member in contact with the surface of the shaft of the roll is made of ceramic.