JPH0790245B2 - Thickness control method for rolled rolled material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a laminated rolling (packing for producing wide and thin materials of non-ferrous metal such as pure Ti and alloy Ti and high alloy steel by hot rolling. (Rolling) plate thickness control method.

[Prior Art] Generally, in non-ferrous metals such as pure Ti and alloy Ti, and high alloy steels, there are many so-called difficult-to-machine materials such as insufficient ductility in hot work and high deformation resistance, and these thin plates are manufactured. There are many problems to be solved. Therefore, a laminated rolling (pack rolling) method has been conventionally known as the thin plate rolling technique.

FIG. 1 shows an explanatory view of the pack shape in pack rolling.

The present pack rolling method is a method in which a desired material is used as a core material 1, the upper and lower sides and four peripheral portions thereof are covered with a cover material 2 and a spacer 3, and the surroundings are welded 4 and the assembled pack material is hot-rolled. It is a method of manufacturing a thin plate of core material by dismantling the material.

However, there is no systematic research on this method, and there is no knowledge of the dimensions of the cover material, core material, spacers, cover material for the core material, spacer material, etc., and it relies on the manufacturer's intuition. However, the following problems have occurred.

[Problems to be Solved by the Invention] In the above-mentioned pack rolling, since the deformation resistances of the cover material and the core material are different, the respective rolling reductions are different, and the laminated plate thickness defined by the ratio of the core material and the pack material is different. Since the ratio changes before and after rolling, it is difficult to obtain an accurate product thickness of the core material without considering the deformation resistance values of the cover material and core material during rolling.

Normally, it is assumed that the laminated plate thickness ratio does not change, and the core material thickness is predicted from the total finished thickness (gauge meter thickness), so the difference from the actual core material thickness becomes large. Therefore, the finishing accuracy becomes poor, which causes a decrease in yield.

The present invention, when manufacturing a thin material of non-ferrous metal such as pure Ti and alloy Ti and high alloy steel by hot rolling, the core material thickness in the pack rolling can be accurately predicted, and the core material finishing accuracy is improved. It is an object of the present invention to provide a method for controlling the plate thickness of rolled rolled material.

[Means for Solving the Problems] The present invention provides a method for hot rolling a pack-rolled material that is assembled by covering the top and bottom of a core material with a cover material, surrounding the area with a spacer, and welding the core material and the cover. Select a core material with a ratio of deformation resistance value of 1 or more, and calculate the length of the core material by the change of rolling load or the output change of gamma-ray plate thickness gauge.
This is a plate thickness control method for a packed rolled material, characterized in that the thickness is obtained from the law of constant volume of the core material.

[Operation] FIG. 1 shows a pack shape in pack rolling.
Reference numeral 1 is a core material, 2 is a cover material, 3 is a spacer, 4 is a welded portion, and 5 is a gap.

Here, the core material 1 is a plate made of a material to be thinned, and one or more sheets each having a surface coated with a release agent are stacked.

The release agent prevents the core materials from adhering to each other and the cover material by rolling, and any release agent may be used as long as it satisfies this requirement.

The upper and lower sides of the core material 1 are sandwiched by the cover materials 2, and the periphery thereof is surrounded by spacers. The cover material 2 and the spacers 3 are welded over the entire circumference to prevent the cover material 2 from peeling off during rolling and breaking of the laminated rolled material.

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

As a result of research on laminated rolling, the inventors have found that when a laminated rolled material configured as described above is hot-rolled, the deformation resistance value of the core material is larger than that of the cover material in the pack material. It was found that the reduction ratio of the cover material is different and the laminated plate thickness ratio before and after rolling is different.

Since only the total thickness of the pack material is known during rolling,
The core material thickness is obtained from the total thickness and the laminated plate thickness ratio, but since the laminated plate thickness ratio is changed by rolling as described above, the core material thickness cannot be accurately obtained and the core material finishing accuracy deteriorates.

Where: Laminated plate thickness ratio Core material / Pack material total thickness = γ Roll rotation speed Vr Advanced rate fs Plate passing speed V Core length during rolling l Core thickness during rolling h Core length before rolling L ₀ Thickness of core material before rolling H ₀ Total thickness of pack material h ₀ Core rolling time t.

In that case, (1) Before rolling, the core material length L ₀ and the core material thickness H ₀ are measured.

(2) The length 1 of the core material is measured when rolling is performed for several passes.

(3) The width expansion of the core material is restrained by the spacers on both sides, so it is very small and can be ignored.

Therefore, the core material thickness is obtained from h = L ₀ H ₀ / l.

(4) If the core material thickness h is within the tolerance of the target plate thickness, rolling is completed.

If it is thicker than the target plate thickness, the rolling amount for the next pass is set and rolling is performed.

The thickness of the finished core material is controlled by performing the steps (2) to (4) at least once.

The details will be described below.

(1) Before rolling, the core length L ₀ and thickness H ₀ can be easily measured during pack assembly.

(2) When the deformation resistance value of the core material is larger than that of the cover material, the elongation of the cover material 2 is larger than that of the core material 1, and as shown in FIG.

When such a material is rolled, the rolling load decreases when the gap 5 is rolled, and the rolling load changes as shown in FIG.

Since A, B, and C in FIG. 3 correspond to the time when A, B, and C in FIG. 2 are rolled, the time t during which the core material is rolled can be known from the load change in FIG. The core material length 1 can be obtained from the roll rotation speed Vr and the advanced rate fs.

l = Vr × (1 + fs) × t As another method, a γ-ray plate thickness gauge is installed on the rolling line and the core material length l in the pack material is determined from the output change of the γ-ray plate thickness meter shown in FIG. You can ask.

From the time t at which the output changes at the front and rear ends of the pack material and the passing speed V of the pack material, 1 = Vt 1 can be obtained.

The output change of the gamma ray plate thickness meter is proportional to the plate thickness and density of the material to be measured.

When the pack material passes points A, B and C in FIG. 4, the thickness and the material of the pack material change.

That is, in A, the output corresponding to the total thickness of the cover material and the spacers, in B, the output corresponding to the upper and lower cover material thicknesses, and in C, the cover material upper and lower 2
The output is equivalent to the number of sheets and the core material.

(3) As described above, the core material width spread is constrained by the spacers on both sides, so it can be ignored, and h = L ₀ . It becomes H ₀ / l, and the core material thickness is obtained.

(4) If the core material thickness h is within the target plate thickness tolerance, the rolling may be finished.

When the core material thickness h is thicker than the target plate thickness, the reduction amount of the next pass is set. At this time, since the total thickness h of the pack material is obtained from the gauge meter, the laminated plate thickness ratio γ is obtained. This laminated plate thickness ratio,
Determine the exit side thickness of the next pass from the total thickness of the pack material. As a method, for example, assuming that the laminated plate thickness ratio γ does not change and the core target thickness is h and the total outgoing thickness at that time is h ₀ ′, h ₀ ′ = h ′ / γ The total thickness can be determined.

However, in this method, the accuracy is not so high because the laminated plate thickness ratio actually changes, but the accuracy can be improved by increasing the number of passes.

The accuracy of the delivery-side total thickness h can be increased by obtaining the relationship between the rolling reduction and the laminated plate thickness ratio in order to compensate for the above-mentioned drawbacks.

The flowchart of (2) to (4) is shown in FIG.

Next, examples of the present invention will be described.

[Example] In order to manufacture a thin plate of Ti-6Al-4V alloy, as shown in Table 1, three Ti-6Al-4V alloy plates were prepared as core materials, and the upper and lower parts and four peripheral parts thereof were covered with mild steel. After covering with material and spacer and welding the surroundings, the inside of the pack material is evacuated to 0.01 torr to create the pack material, heating time 9 hours, heating temperature
After heating at 850 ℃, reverse rolling is performed with a thick plate mill,
Hot rolling was performed by dividing the rolling pass schedule into the conventional method and the method of the present invention.

In addition, in order to facilitate the peeling of the core materials after rolling and between the core materials and the cover material, a release agent shown in Table 2 is applied between the core materials.
And applied between the core material and the cover material.

The rolling method in which the target thickness for the three core materials after the rolling was 8.6 mm was compared by the conventional method and the invention method.

(1) Conventional method Assuming that the rolling resistance values of the cover material and core material are the same, rolling was carried out according to the 10-pass pass schedule shown in the third hail.

In this case, the thickness ratio between the core material and the material is 8.6 / 8.9 × 3 = 0.322, so the thickness of the pack material after 10 passes is 71.65 × 0.322 = 23.08 (mm).

The target of the thickness of the pack material after 10 passes was 23.08 mm, and the distribution of the reduction ratio of each pass was taken as shown in Table 3 and rolled.

After rolling, the product was disassembled and peeled off, and the thickness of three core materials was measured to be 8.9 mm, which was 0.3 mm off from the target thickness of 8.6.

This is due to the difference in rolling resistance between the cover material and the core material.

(2) Inventive method Rolling was performed from 1 pass to 7 passes with the same reduction ratio distribution of each pass as in the conventional method, and from the 7th pass to the 10th pass, the γ-ray plate thickness gauge shown in FIG. 4 was used. The elongation length of the core material was measured, and rolling was performed after 8 passes.

The core material length after 7 passes is 4060 mm in the gamma ray plate thickness gauge, and the thickness is 11.9 mm according to the law of constant volume.

Since the target thickness of the core material after rolling is 8.6 mm, the length is 5620 mm according to the law of constant volume.

Therefore, the changes in length of the core material after 7 passes and the target length after 10 passes were distributed to 8, 9, and 10 passes as shown in Table 4, and rolled.

After rolling, the product was disassembled and peeled off, and the thickness of three core materials was measured to be 8.65 mm, which was only 0.05 m from the target thickness of 8.6 mm.
It was an error of m.

[Effects of the Invention] According to the method of the present invention, the following effects are exhibited.

(1) The core material thickness finishing accuracy is improved and the yield is improved.

(2) In the refining process after rolling, machining for adjusting the finished thickness is not required, which improves production efficiency and reduces cost.

[Brief description of drawings]

FIG. 1 is an explanatory view of the pack shape in pack rolling, and FIG.
The figure is an explanatory view showing the difference in elongation between the core material and the cover material, FIGS. 3 and 4 are explanatory views showing the relationship between time, rolling load and γ-ray output, and FIG. 5 is a flowchart of the present invention. . In the figure, 1: core material, 2: cover material, 3: spacer, 4: welded part, 5: gap are shown.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ariizumi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Toshinori Matsuo 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Pipe Co., Ltd. (72) Inventor Junzo Tamai 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) Reference JP-A-48-86762 (JP, A) JP-A-59 -42102 (JP, A)

Claims (1)

[Claims] 1. A method of hot rolling a pack rolling material, which is constructed by covering a core material with a cover material on the upper and lower sides, surrounding the core material with a spacer, and welding the pack material. The core material is selected as described above, the length of the core material is determined by the change in rolling load or the output change of the gamma ray plate thickness gauge, and the thickness is determined by the volume constant rule of the core material. Plate thickness control method.