JPH03128103A - Cold rolling method for titanium - Google Patents

Abstract

PURPOSE:To obtain titanium whose gloss is excellent by using a work roll whose material is made in a specified value at the component ratio of WC, a specified value at the component ratio of Co and whose Young's modulus is made in a specified value, and rolling it with the rolling reduction rate per one pass being less than the specified value. CONSTITUTION:Rolling is executed by using a work roll 1 with the rolling material of the work roll 1 being at 70-85% the component ratio of WC, 15-30% the component ratio of Co and 39000-50000KGf/mm<-2> Young's modulus, and with the rolling reduction rate per one pass being at less than 35%. The preven tion from the roll coating of titanium stuck to the working roll 1 during rolling is possible, in the case of cold rolling of the metal strip of titanium and espe cially the metal strip of titanium excellent in the surface gloss can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cold rolling titanium, and particularly to a method for cold rolling a titanium metal strip with excellent surface gloss.

(Prior Art) Roll coating is a problem when cold rolling titanium, which has excellent surface gloss. Roll coating in cold rolling of titanium is a white titanium oxide formed by the material titanium baked onto the work roll during rolling. When roll coating occurs, the surface roughness of the work roll increases and the surface gloss of the rolled plate deteriorates. Further, due to the occurrence of roll coating, the rolling load increases and the rolling reduction per bath decreases, so the number of rolling baths required to roll the sheet to the target thickness increases, leading to a decrease in productivity. Further, such a change in rolling G1 speed also has a negative effect on the shape of the plate. As described above, when titanium is cold-rolled, roll coating occurs, making it difficult to produce high-gloss products such as stainless steel.

As a way to prevent such roll coating,
■A method for developing a rolling lubrication part for cold rolling of titanium, as shown in Japanese Patent Application Laid-Open No. 54-145349;
■ A method of forming a pre-coat film on the surface of titanium before rolling, as shown in JP-A-54-88858; A method of selecting the work roll diameter based on the average crystal grain size has already been reported.

(Problem to be Solved by the Invention) Usually, a cluster type rolling mill with a work roll diameter of about 60 m1, such as the Sendzimir rolling mill, is used as a rolling mill for rolling titanium, and stainless steel is also rolled at the same time. There are many. Under such circumstances, it is extremely difficult to switch the rolling lubricating oil between rolling stainless steel and rolling titanium. Also,
The method of forming a pre-coat film on the surface of titanium in advance increases costs. Furthermore, in a cluster type rolling mill, it is difficult to change the work roll diameter too much due to the structure of the rolling mill.

The present invention solves the above-mentioned problems, and provides a rolling method that prevents roll coating in which titanium burns onto the work roll during cold rolling when titanium metal strip is rolled. It is an object of the present invention to provide a cold rolling method for easily manufacturing titanium metal strip.

(Means for Solving the Problems) In order to achieve the above object, the titanium cold rolling method of the present invention uses a roll material made of WC and Co as a work roll. That is, this roll material is WC
The component ratio of Co is 70 to 85%, and the component ratio of Co is 15 to 3.
0%, Young's modulus of 39,000 to 50,000 kgf-mm
-2. Then, using a work roll made of such a material, cold rolling is performed at a rolling reduction rate of 35% or less per bath.

The present invention will be explained in detail below.

In the present invention, the material of the work roll is WC and C.
The reason why we chose the roll material made of O is that it is difficult to seize against titanium, and experiments have shown that it is not as brittle as SiAlON and is relatively inexpensive. be.

In addition, the reason why the Co component ratio was set to 15% to 30% was because Co
is less than 15%, the Young's modulus of the roll is 50,000
This is because if the rolling capacity exceeds kg f -mm-', the shape of the plate during rolling deteriorates and breakage of the plate due to drawing occurs frequently.

In addition, the reason why the component ratio of Co was set to 30% or less was to reduce the wear resistance and seizure resistance of the roll, and because the Young's modulus of the roll was less than 39,000 kg f・mu−2. This is because the effect of reducing the rolling load due to the increase in is reduced. In addition, the rolling reduction rate per bath is 3
The reason why it is set at 5% or less is that the seizure resistance of the roll is lost if the rolling reduction exceeds 35%.

(Function) When the work roll according to the present invention is used when cold rolling a titanium metal strip, it is possible to prevent the roll coating in which titanium burns onto the work roll during rolling, and in particular, it is possible to prevent the roll coating of titanium from burning onto the work roll during rolling. A titanium metal strip with excellent luster can be easily produced.

(Example) FIG. 1 shows an embodiment of a rolling mill.

The rolling mill used has a work roll 1 with a diameter of 50 mm and a body length of 4.
00mm 12-high cluster rolling mill. This work roll has a WC component ratio of 87.5%, a CO component ratio of 12.5%, and a Young's modulus of 47000 kg f -m+
s-2 roll and was manufactured using the CIP process.

Further, the surface of the work roll is finished by lapping to have a surface roughness of 0.015-Ra.

The intermediate roll 2 has a roll material equivalent to SUJ 2,
The roll diameter is φ75ffi11. Further, this rolling mill drives four intermediate rolls 2. The central backup roll 3 has a roll diameter of 150 mm and is divided into four parts in the lengthwise direction of the body. Further, the side-divided backup roll 4 has a roll diameter of 150 mm and is divided into five parts in the body length direction.

The material 5 used for rolling is a second type titanium sintered and degreased coil, and the plate thickness is 100-1 and the plate width is 100 mm.

The surface roughness of this titanium coil is 0.105 as an average value in the L-C direction. csRa and glossiness are 347% as an average value in the LC direction at 0345 degrees. Reduction rate is 2-40% per bath, forward tension is 35kg f-mm-2
The rolling was carried out at a rear tension of 30 kg f*mm-2 and a rolling speed of 3 m-ff1 in-'. For rolling lubrication, commercially available mineral-based rolling lubricating oil was used at a temperature of 40° C. and 21-ton lubrication.

Further, in order to compare the effects of the present invention, rolling was performed using forged steel, high speed steel, sialon, and carbide as work roll materials. Note that the roll roughness of these work rolls is 0.
It is within 0.019-0.032 um Ra.

In order to investigate the influence of roll coating, a rolling experiment was conducted immediately after changing the rolls, and after rolling a length of 200 m at a rolling rate of 30%, a rolling experiment was conducted again.
The influence of roll coating was investigated.

FIG. 2 shows the effect of roll coating on rolling load. From FIG. 2, it can be seen that the rolling load of high speed steel, forged steel, and cemented carbide increases due to the influence of roll coating. In the case of carbide, the plate frequently broke due to poor shape during rolling.

Figure 3 shows the effect of roll coating on surface gloss. From FIG. 3, it can be seen that even when roll coating occurs, the gloss level does not decrease in the rolls of carbide, sialon, and the present invention.

Figure 4 shows the rolling reduction rate of 10.20°2 using the roll of the present invention.
5, 30, 35, and 40%, showing changes in gloss when rolling a rolling length of 50 m in descending order of rolling reduction.

As is clear from FIG. 4, it was found that the surface gloss decreased when the rolling reduction exceeded 35%.

Therefore, in the present invention, it is necessary to suppress the rolling reduction rate per bath to 35% or less.

(Effects of the Invention) As described above, in the present invention, when cold-rolling a titanium metal strip, it is possible to prevent roll coating in which titanium burns onto the work roll during rolling, and in particular, it is possible to prevent roll coating where titanium burns onto the work roll. A titanium metal strip with excellent luster can be easily produced.

[Brief explanation of the drawing]

Figure 1 shows an example of this experiment. Schematic diagrams, Figures 2 a) and b) show the influence of roll coating on rolling load, Figure 3 a) and b) show the influence of roll coating on surface gloss, and Figure 4 The figure is a diagram showing the applicable range of the rolling reduction rate per pass of the present invention. 1: Work roll 2: Intermediate roll 3: Central backup roll 4: Side backup roll 5 Ni-titanium coil

Claims (1)

[Claims] When rolling a titanium metal strip using a rolling mill with a pair of work rolls, the roll material of the work rolls is set such that the WC component ratio is 70 to 85%, the Co component ratio is 15 to 30%, and the Young's modulus is 39000~50000kg
Using a work roll with f・mm^-^2, and 1
A method for cold rolling titanium, characterized by rolling at a reduction rate of 35% or less per pass.