JPH01301841A - Electrifying roll for continuous electrogalvanizing for metallic strip and its production - Google Patents

Abstract

PURPOSE:To prevent local corrosion, etc., at the surface and to prolong the service life of a roll by fitting an internal cylinder composed of a steel in which respective contents of Cr, Mo, and Ni are specified in an external cylinder composed of an Ni steel in which respective contents of Cr and Mo are specified and then subjecting the above to heating under the prescribed conditions and to accelerated cooling. CONSTITUTION:An internal cylinder 6 is formed of a stainless steel having a composition consisting of, by weight, 15-26% Cr, 1-4% Mo, 8-18% Ni, and the balance Fe. Further, an external cylinder 7 is cast by means of centrifugal casting by using a high-Ni alloy steel having a composition consisting of 15-25% Cr, 5-20% Mo, and the balance Ni. The above internal cylinder 6 is fitted in this external cylinder 7, which is inserted into a high-pressure vessel 12. Subsequently, this vessel 12 is filled with inert gas and then held under 500-2,000kgf/cm<3> pressure, at 700-1,200 deg.C, for a prescribed period. After the above procedure, accelerated cooling is applied to the above to carry out integral adhesion forming.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a current-carrying roll used as a cathode in an apparatus for continuously electroplating metal strips such as steel strips, and a method for manufacturing the same.

[Prior Art] As shown in Fig. 2, a normal electroplating line is arranged above and below a steel strip through which a cathode electrode 1 is passed, and a plating solution is supplied from nozzles 2. It is a roll that rotates in contact with the copper strip.

4 is an auxiliary roll that supports the standard roll 3, and 5 is a tank that receives the plating solution.

As shown in Fig. 2, the structure of this energizing roll 3 is that an outer cylinder 7 made of high Ni alloy is inserted into the surface of an inner cylinder 6 made of stainless steel, and after inserting a sleeve 8 into this double cylindrical shell. , fixed by welding. 9 in the figure indicates a cooling water pipe for cooling the rolls.

The current-carrying roll with the structure shown in Figure 3 usually has a hydrogen ion concentration of 1.
．． Since it is used in contact with a plating solution of 0 to 1.2, the surface becomes rough due to corrosion and wear is severe due to wear. The number of days that online equipment can be used is extremely short, ranging from 10 to 25 days depending on the conditions of use, and the materials themselves are expensive, which is a major factor in increasing maintenance costs.

Conventionally, the method for manufacturing the energized roll shown in Fig. 3 is to form the outer cylinder 7 in the figure into a cylinder by centrifugal casting, etc., finish the inner surface to a high degree of roughness by machining, and then mold the outer cylinder 7 in the figure into a cylinder with a high precision outer surface made of stainless steel. A method has been adopted in which the bonding cloth 9 is inserted into the inner cylinder 6 of the fabric and tightly fixed by shrink fitting.

Furthermore, as disclosed in Japanese Patent Laid-Open No. 56-87608, a method has been proposed in which an alloy powder prepared to have the chemical composition of a sintering energizing roll is sintered and formed using a high-temperature and high-pressure apparatus.

[Problems to be Solved by the Invention] When the outer cylinder 7 is formed by centrifugal casting, there are casting defects or pores inside, although these are small, and these assist the penetration and diffusion of the plating solution, resulting in the formation of localized parts. This corrosion causes pin-like or "pock-like" flaws, which is the main cause of replacement in the electrolytic galvanizing line where the present inventors work.

In addition, the metal structure itself becomes coarse, which is typical of casting, and the crystals become larger. As a way to alleviate this,
Generally, grains are made finer by heat treatment, but
The effect of molding is also inferior in terms of performance such as mechanical properties when rolled or forged. In addition, in the case of casting, segregation of molybdenum, etc. is noticeable. The present inventors have discovered that if the plating solution penetrates into this segregated area and exists as an electrolyte,
It is believed that a local battery forms in that area and accelerates corrosion.

As a method to solve these problems of casting, there are two methods: using rolled material and using forged material.If rolled material is used for the outer cylinder 7, it is formed into a cylinder by bending and then welded. It is necessary to join the ends.

In this case, since the corrosion rates of the rolled base material and the weld metal part are different, a linear pattern is generated in the width direction of the roll along the welded part, and this pattern is transferred to the copper strip. In addition, when manufacturing by forging, generally a steel ingot or an extremely thick cylindrical ingot is machined down to roll dimensions after forging, resulting in poor yields.
Its cost is high.

When manufacturing by the sintering method as in JP-A No. 56-87608, the alloy powder is expensive, and a sealing process called canning is used during molding, which complicates the process due to stiffness and increases processing costs. increases.

When the shrink fit method is adopted as a method for joining the inner cylinder 6 and the outer cylinder 7, the machining cost is extremely high because the inner and outer surfaces of each are machined to a finishing precision close to that of polishing. . If the adhesion of this bonding cloth 9 is not sufficient, problems may occur such as an increase in electrical resistance during energization or a decrease in heat transfer efficiency when the cooling water passing through the cooling water pipe 10 cools the outer cylinder 7. .

Therefore, the inventors of the present invention have provided a current-carrying roll that has excellent durability, particularly strength and corrosion resistance, without impairing electrical resistance during energization compared to conventional current-carrying rolls. In particular, the method of the present invention is excellent as a method for increasing the adhesion between the energized roll (inner cylinder) and the outer cylinder, and is suitable for high-speed, continuous processing of metal strips.

[Means to solve the problem] The gist of the present invention is as follows.

11% by weight, Cr: 15-2H+, Mo1l-4
%, Ni: 8 to 18 tons, balance Fe and unavoidable impurities, and a high Ni alloy consisting of Cr: 15 to 25 J, Mo: 5 to 20 tons, balance Ni and unavoidable impurities, in weight %. 1. An energizing roll for continuous electrogalvanizing of a metal strip, comprising: a steel outer cylinder; and the outer cylinder is inserted into the outer periphery of the inner cylinder and integrally molded in close contact with the inner cylinder.

2. In a method for manufacturing a current-carrying roll for electrogalvanizing, which involves inserting an outer cylinder in contact with a metal strip into the surface of the current-carrying roll and integrally molding this, the chemical composition of the current-carrying roll is Cr: 15 to 15% by weight. 26%
, Mn: 1~4!1; , Mi: 8~+89
6. The outer cylinder is made of stainless steel with the remainder being Fe and unavoidable impurities, and the outer cylinder is cylindrically formed by centrifugal casting, and the chemical composition is as follows: Gr: 15-25%, Mo: 5% by weight.
High Nj consisting of ~20t, balance Ni and unavoidable impurities
As an alloy steel, the energized roll is charged into a pressurized container,
Internal pressure 500-2000K after filling with inert gas
1. A method for producing a current-carrying roll for continuous electrogalvanizing of a metal strip, which comprises heating to 700 to 1200° C. at a temperature of 700 to 1200° C. and then cooling it at an accelerated rate.

[Function] In the energized roll of the present invention, the inner tube and the outer tube have a composition within a predetermined range of ingredients and are in close contact with each other, so the internal structure is dense and the mechanical properties are comparable to those of rolled or forged materials. improves. Furthermore, the electrical resistance when energized does not increase. On the other hand, according to the method of the present invention, the above-mentioned energized roll can be manufactured efficiently, casting defects and pores during centrifugal casting can be significantly improved, and the bonding surface between the inner cylinder and the outer cylinder can also be mutually diffused. This allows complete contact in the same phase. In addition, the segregation of elements such as molybdenum is diffused relatively uniformly, and can be prevented to some extent from being unevenly distributed in the peripheral portion.

In addition, in the method of the present invention, the heating temperature is 700 to 1200°C.
The reason for this limitation is that below this temperature, alloying elements such as molybdenum cannot be redissolved and diffused smoothly, and above this temperature, energy is consumed but the effect is small.

In addition, the reason why the pressure is limited to 500 to 2000 kgf/cm2 is that below this value, the effect of improving casting defects, pores, and mechanical properties is small, and if it is above this value, equipment costs will increase and manufacturing costs will increase significantly. This is to do so.

Furthermore, accelerated cooling, such as rapid cooling (by water cooling method), before the temperature drops after high temperature and high pressure treatment is a measure to prevent the crystal grains of the nickel alloy from becoming coarser due to slow cooling. Accelerated cooling here refers to a method of rapidly cooling the inner and outer cylinders by inserting them into a water tank filled with room-temperature water while still in a high temperature state (700 to 1200°C) so that the inner and outer cylinders are completely immersed. desirable.

[Example] The chemical compositions of the inner cylinder 6 and outer cylinder 7 of the current-carrying roll shown in FIG. 3 were as shown in Table 1. After forming this outer cylinder 7 into a cylinder close to the finished size of the roll using a centrifugal casting method, it is inserted into a stainless steel inner cylinder 6, and the circumference of the cylinder end at the joint surface of the inner and outer cylinders is welded to form a seal 11. , the double-layered state is charged into the high-pressure container 12 shown in FIG.
The pressure is increased within the range of 0 kgf/mm2. At this time, the internal temperature is heated to 700 to 1200°C using the heater 15, and this state is maintained for a certain period of time. After that, it was poured into cooling water and rapidly cooled. In addition, in FIG. 1, 16 in the figure is the lid of the charging section, 1
Reference numeral 7 indicates a screw-in portion of the lid, 18 indicates a heat insulating material, 19 indicates a roll stand, and 20 indicates a high pressure gas introduction pipe.

Table 1 (% by weight) Table 2 shows the results of measuring the mechanical properties of the cylindrical shelf manufactured according to the present invention, the conventional centrifugal casting method only, the forged shell, and the rolled plate shell. In the conventional manufacturing method, an outer cylinder made of the materials shown in Table 1 is manufactured by centrifugal casting.

As a result, the tensile strength and Shore hardness of the product obtained by the production method of the present invention were significantly improved compared to the conventional product.

Table 2 also shows the corrosion resistance of 50 at the boiling point temperature of sulfuric acid and in the immersion state. In the weight loss test per unit surface area per number of days in the forest, the conventional method of centrifugal ZJi construction using the outer cylinder materials shown in Table 1 resulted in a loss of 0.0.
The production method according to the present invention improves the rlJ from 5 g/cm 2 ·day to 0.005 g/cm 2 .

Table 3 shows the wear amount of the roll outer diameter per unit of days when the roll according to the present invention is actually used in the actual machine shown in Table 2. Its consumption is definitely decreasing. In addition, the amount of wear on the outer diameter is the average value of 18 N rolls, which is calculated by subtracting the outer diameter after use from the outer diameter before use at the center of the roll in the 1] direction, and dividing by the number of days the roll is used. .

Table 3 [Effects of the Invention] The current-carrying roll according to the present invention can significantly reduce the occurrence of surface flaws, greatly improve roll life, improve mechanical performance, and reduce wear caused by metal strips. Also, since significant segregation of molybdenum and other substances is eliminated, corrosion or roughening of the surrounding area can be reduced.

Further, according to the manufacturing method of the present invention, the above-mentioned roll can be manufactured reliably, and even if it is formed into a cylinder by centrifugal casting, casting defects and pores can be improved to the same degree as rolled or forged materials. The occurrence of pinpoint flaws, pock-like flaws, etc. can be prevented. In addition, conventionally the inner cylinder 6 and the outer cylinder 7 were shrink-fitted by a processing process similar to polishing, but by performing the process of the present invention, the joining surfaces 8 are solidified and completely joined, making it possible to use Loosening due to internal rotational force and thermal expansion differences can be prevented, and the electrical resistance and thermal resistance of the joint surfaces are also almost eliminated. According to the present invention, processing to obtain these excellent properties can be done at a lower cost than with conventional forging methods.
Moreover, since the heat treatment process after forging (or rolling material welding) is simplified, the manufacturing period can also be shortened.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of the method of the present invention (example device). Second
FIG. 1 is an explanatory diagram showing an example of application of the energizing roll. FIG. 3 shows the structure of a conventional energizing roll. 1... Anode electrode plate, 2... Plating solution nozzle, 3...
・Electrification roll, 4... Auxiliary roll, 5... Tank,
6... Roll inner cylinder, 7... Roll outer cylinder, 8... Shaft, 9... Joint surface, IO... Cooling water pipe, 11... Seal welded part, 12... High pressure customer 13...Internal filling inert gas, 14...Compressor, 15...Heater,
+6...;1. +7...screw, 18...insulating material, 19...roll mounting stand, 20...high pressure gas introduction pipe.

Claims (1)

[Claims] 1. In weight%, Cr: 15-26%, Mo: 1-4%,
An inner cylinder made of stainless steel consisting of Ni: 8 to 18%, balance Fe and unavoidable impurities; An energizing roll for continuous electrogalvanizing of a metal strip, comprising: an outer cylinder made of Ni alloy steel; and the outer cylinder is inserted into the outer periphery of the inner cylinder and integrally molded in close contact with the outer cylinder. 2. In a method for manufacturing a current-carrying roll for electrogalvanizing, which involves inserting an outer cylinder in contact with a metal strip into the surface of the current-carrying roll and integrally molding this, the chemical composition of the current-carrying roll is Cr: 15 to 15% by weight. 26%,
As a stainless steel consisting of Mn: 1 to 4%, Mi: 8 to 18%, and the remainder Fe and unavoidable impurities, the outer cylinder was formed into a cylinder by centrifugal casting, and the chemical composition is C in weight%.
As a high Ni alloy steel consisting of r: 15-25%, Mo: 5-20%, balance Ni and inevitable impurities, the energized roll is placed in a pressurized container and filled with inert gas,
700~ at internal pressure 500~2000Kgf/cm^2
A method for producing a current-carrying roll for continuous electrogalvanizing of a metal strip, which comprises heating to 1200°C and then accelerated cooling.