JPH07108402B2 - Heat rolling method for multi-layer pack rolling material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a multi-layer pack for producing thin materials (5 mm or less) of non-ferrous metals such as pure Ti and alloy Ti and high alloy steel by hot rolling. The present invention relates to a method for heating and rolling a laminated rolled material.

[Conventional technology]

The laminating and rolling method (pack rolling method) is usually used for manufacturing wide and thin materials such as pure Ti and alloy Ti.

This is because several layers of core material Ti are coated with a release agent and the whole material is wrapped in mild steel or pure iron.The material is hot rolled and then cooled. This is a method of peeling the plates one by one to obtain a thin plate.

When a large number of core materials are laminated, a temperature difference occurs between the core materials, which causes a difference in the deformation resistance of each core material. This difference in deformation resistance causes variations in the finished plate thickness of the core material, resulting in poor plate thickness accuracy. In order to compensate for this variation, the target plate thickness is set to be thicker, which causes a problem such as a decrease in yield.

[Problems to be solved by the invention] In the present invention, in producing a wide thin material (5 mm or less) of a special metal such as pure Ti or alloy Ti by hot rolling, it is possible to improve the thickness accuracy of the core material. An object of the present invention is to provide a method for heating and rolling a multi-layer pack rolling material which improves yield and reduces core length defects.

[Means for solving problems]

The present invention is a core material obtained by stacking three or more layers of core material having a release agent applied on the surface, covering the top and bottom of the core material with a cover material, enclosing the surroundings with spacers, and assembling them by hot rolling to obtain a core material. In the laminated rolling for manufacturing the thin material, the temperature of the outer core material is preheated to be higher than the temperature of the inner core material, and the temperature distribution due to cooling during rolling is corrected to reduce the variation in temperature between core materials. It is a characteristic method for heating and rolling a multi-layer pack rolling material.

[Action]

FIG. 1 shows the structure of the laminated rolled material in cross section. In the figure, 1,1 ': core material, 2: cover material, 3: spacer, 4: welded part.

The names of laminated rolled materials used below are as shown in FIG.

Here, there are three or more core materials, and a release agent is applied to the surface of the core material to prevent the core materials from sticking to each other and the core material and the cover material from adhering by rolling.

It is sandwiched between the cover materials 2 above and below the core materials 1 and 1 ′, and the periphery thereof is surrounded by the spacer 3 of the same material of the cover material 2. Cover material 2
The spacer 3 is welded over the entire circumference to prevent the cover material 2 from peeling off during rolling and the laminated rolled material from breaking.

The laminated rolled material is filled with air or other gas, or in a vacuum atmosphere.

Consider the effect of the number of core materials 1,1 'on the thickness accuracy of such laminated rolled materials.

When stacking three or more core materials, the laminated core material cools from the outside during rolling, so the outer core material 1 cools more than the inner core material 1.

FIG. 2 shows a temperature change when a laminated rolling material in which three core materials are stacked is rolled. As shown in FIG. 2, such a temperature difference occurs in any laminated rolled material.

Since the deformation resistance changes depending on the temperature as shown in FIG. 3, the deformation resistances of the inner core material and the outer core material differ by the temperature difference generated in the core material.

Due to this deformation resistance difference, the rolling reduction of the inner core material becomes larger than the rolling reduction of the outer core material, and the finished plate thickness of the inner core material becomes smaller than the finished plate thickness of the outer core material.

Therefore, in order to prevent variations in the finishing thickness of the core material during laminated rolling, the temperature of the outer core material is set higher than the temperature of the inner core material in advance, and the material is gradually cooled from the outside during rolling, and the core material is subjected to the entire rolling process. By minimizing the variation in temperature between them, it is possible to minimize the difference in elongation and the difference in rolling reduction between core materials, and the variation in plate thickness is minimized.

However, any method may be used as the method of making the temperature difference in advance.

Next, examples of the present invention will be described.

〔Example〕

As shown in Fig. 1, 8.9 ^t mm3 Ti-6Al was used as the core material 1.
A laminated rolling material was formed by using SS41 of -4V and 22.4tmm as the cover material 2, and hot rolling was performed under the following experimental conditions.

Heating conditions (1) 950 ° C soaking and heating (2) 750 ° C soaking, then 1200 to make temperature difference
Heated at 0 ° C for 7 minutes.

Rolling conditions 71.5 ^t mm → 21.5 ^t mm, roll diameter 1200 mm Rolling with 10 passes Figure 4 shows the temperatures of the outer and inner core materials and cover material under heating condition (2).

It should be noted that 90 seconds from extraction to the start of rolling “●” 〃 180 seconds “○” From this Fig. 4, it can be seen that at 90 seconds, the outer core temperature is high at the beginning and reverses in the middle.

Due to this effect, the variation in plate thickness between core materials is reduced as compared with the case of 180 seconds.

However, even in the case of 180 seconds, the plate thickness variation between the core materials is small as compared with the soaking and heating material. The results are shown in Table 1.

The time indicates the time from the heating furnace extraction to the start of rolling.

From the results shown in Table 1, in order to make the effect of the present invention even greater, heating was performed in consideration of the time distribution from the furnace extraction to rolling and the temperature distribution of each core material during rolling determined by the pass schedule. You have to decide how.

〔The invention's effect〕

According to the heating and rolling method of the multilayer pack rolling material of the present invention,
Variations in the plate thickness of the core material can be prevented, and the yield is improved accordingly, and the accuracy and precision are reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a laminated rolling material structure of the present invention,
FIG. 2 is an explanatory view showing a temperature change when a laminated rolling material in which three core materials are stacked is rolled, and FIG. 3 is Ti-6Al-4V.
FIG. 4 is a graph showing the relationship between the deformation resistance and the rolling temperature, and FIG. In the figure, 1,1 ': core material, 2: cover material, 3: spacer, 4: welded part. . In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Arizumi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Makoto Yamada 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) References JP-A-48-86762 (JP, A)

Claims (1)

[Claims] 1. A laminated rolling material obtained by laminating three or more layers of a core material coated with a release agent on the surface, covering the upper and lower sides thereof with a cover material, enclosing a periphery with a spacer and welding and assembling, and hot rolling.
In laminated rolling for manufacturing thin core materials, the outer core material temperature is preheated to be higher than the inner core material temperature, the temperature distribution due to cooling during rolling is corrected, and variations in core material temperature are reduced. A method for heating and rolling a multi-layer pack rolling material, which is characterized in that.