JPH0510161B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a technology for a continuous rolling mill with different circumferential speeds that can achieve a large rolling reduction amount with a small number of rolling mills. [Background of the Invention] In recent years, there has been a strong desire to convert the manufacturing process in rolling mills from the conventional individual-independent method to a series of continuous lines with the aim of saving labor and energy. The cold rolling mill, cleaning, annealing and temper rolling have already been completed.
Although a specialized equipment has been realized, the line speed in this case is mainly controlled by the speed of continuous annealing. In general, the rolling speed of a cold rolling mill is economically 3 to 5 times higher than the annealing speed, and therefore, the disadvantage is that the rolling speed is kept to an uneconomical low rolling speed by integrating them. To compensate for this, it is necessary to reduce the number of rolling mill groups, that is, reduce the number of tandem mill stands to satisfy economic efficiency. Figure 1 shows a 4-high rolling mill (hereinafter referred to as 4H mill), which is a typical conventional rolling mill. This 4H mill has upper and lower work rolls 1 and 2.
2 are supported by reinforcing rolls 4 and 5, respectively, and rolling is performed between upper and lower work rolls 1 and 2. Although not shown, the 4H mill also includes other components that account for a large portion of the cost, such as a roll stand, a rolling device, and a roll drive device. Therefore, as shown in FIG. 2, if rolling can be carried out twice at the same time by simply adding one more work roll, the effect would be great. However, in normal rolling, 1
The peripheral speed of the set of work rolls 1, 2 or 2, 3 is kept the same, and the speed is approximately equal to the exit speed of the rolled material, and the inlet speed of the rolled material is slower than the roll peripheral speed by approximately the reduction rate γ. Become. By the way, in rolling as shown in FIG. 2, the circumferential speeds v ₁ ,
Since v ₂ and v ₃ are respectively equal, v ₁ = v ₂ , v ₃ = v _3. Therefore, v ₁ = v ₂ = v ₃ , and work rolls 1 and 2
The speed v _S2 of the rolled material 10 that has passed through is v _S2 ≒ v ₂ = v ₃ ≒ v _S3 Also, the speed v _S2 ′ of the rolled material 10 guided to the work rolls 2 and 3 is v _S2 ′≒ v _S3 (1−γ) =v _S2 (1-γ) That is, v _S2 ′<v _S2 , and slack is created in the rolled material 10 on the exit side of the work rolls 1 and 2. Therefore, a loop force 6 is required to absorb the slack of the rolled material. Now, suppose the speed of the rolled material after passing through work rolls 2 and 3
Assuming that v _S3 is v _S3 = 500 m/min and rolling reduction rate γ = 30% by work rolls 2 and 3, loop force 6 is V = v _S2 − v _S2 ′/2 = 1/2 {v _S2 − v _S3 (1-γ)} =1/2v _S3 {1-(1-γ)}=1/2v _S3 γ=500/
It is necessary to move at a speed of 75 m/min (2 x 0.3 = 75 (m/min)) during rolling, which makes it especially impossible to apply to a continuous line. Therefore, to prevent such a situation, v _S2 =
The condition v _S2 ' must be satisfied, and for that purpose, it is necessary to hold at least the relationship v ₃ > v ₂ or v ₂ > v ₁ . This is already called different circumferential speed rolling (PV).
It is known as. Before proceeding with the discussion, I will provide an overview of different circumferential speed rolling. In Figure 3, a is normal constant speed rolling (NR)
The neutral angle φ, which is the point where the circumferential speed of the roll and the speed of the rolled material match, is equal for the upper and lower rolls, and if the neutral angle of the upper roll is φ ₁ and the neutral angle of the lower roll is φ ₂ , then θ<φ ₁ =φ ₂ <0. In this case, the drive torque F of the roll is applied to the material as a tangential force due to the friction between the roll and the rolled material, but the force F is maximum when φ ₁ = φ ₂ = 0, and this is set as F ₀ , when φ ₁ = φ ₂ > 0, if the rolling pressure p and the friction coefficient μ between the roll and the material are approximated as constant over the contact length, then F=F ₀ (θ−φ ₁ )−φ ₁ +(θ− φ ₂ )−φ ₂ /2θ=F
₀ θ−(φ ₁ +φ ₂ )/θ…(1) If φ ₁ =φ ₂ =φ, then F=F ₀ θ−2φ/θ=F ₀ (1−2φ/θ)…(2). In PV rolling shown as b in Fig. 3, φ ₁ = θ,
Inserting φ ₂ =0 into equation (1), F=F ₀ θ−(θ+0)/θ=0 (3), and the upper and lower rolls cannot apply a tangential force to the material in total. That is, the energy necessary for rolling cannot be supplied from the rolls, and instead, the difference in tension between the rolled material on the input and exit sides of the rolled material is used. The relationship is generally expressed by the following equation. σ _d −σ _e =Sln1/1−γ …(4) where σ _d , σ _e Tension of rolled material on exit/input side Kg/mm ² S Average deformation resistance of rolled material Kg/mm ² γ Reduction rate For example, if rolling is performed at a rolling reduction of 50%, σ _d −
σ _e =0.69S, which is extremely high and there is a risk of plate breakage. However, this rolling method has the effect of significantly reducing the rolling load because shear force in addition to vertical pressure acts on the rolled material and the peak of rolling pressure called friction hill that occurs in NR does not occur. A method that slightly sacrifices the advantages of this PV rolling method and compensates for its disadvantages is an intermediate method between NR rolling and PV rolling, which is called NPV and is shown in Figure 3c. In this case, since φ ₂ ≒0, the tangential force F is F=F ₀ θ−φ ₁ /θ from equation (1), so that θ<φ ₁ and therefore F>0. According to this method, the effect of reducing the rolling load can be expected, and rolling at different circumferential speeds can be performed without increasing the strip tension excessively. Now, if rolling at different circumferential speeds can be performed, continuous rolling can be performed twice with the same roll without causing a loop as shown in FIG. The state of continuous rolling is shown in FIG. In the figure, a rolled material 10 is sequentially rolled by rolls 1, 2, 3, and 4, and after rolling, it is wound around rolls 2 and 3, respectively, for the next rolling. In this case, the rolling method
PV rolling method and NPV rolling method can be applied. As mentioned above, NR rolling cannot be performed. PV and
The first step is to simplify the characteristics of the continuous rolling method using NPV.
Shown in the table.

【table】

Claims (1)

[Scope of Claims] 1. In a continuous rolling mill that has one roll that rolls at two or more points simultaneously, and that rolls a material to be rolled continuously by the rolls, the rolls adjacent to the rolls are mutually The material to be rolled is rolled at different circumferential speeds, and the material to be rolled is rolled at different circumferential speeds, and the material to be rolled, which has passed through the first rolling point of the roll and is separated from the surface of the roll, is guided to the second rolling point of the roll. A tension difference applying device consisting of a roller and a drive device that rotationally drives the roller is installed to apply a tension difference to the rolled material, and the tension difference applying device is installed between the first rolling point exit side and the second rolling point exit side of the rolled material.
A continuous rolling mill with different circumferential speeds, characterized in that a tension difference is generated between the inlet side of the rolling point and the inlet side of the rolling point. 2. In claim 1, the tension difference adding device applies tension to the rolled material from the first rolling point exit side of the roll to the tension difference adding device,
A different circumferential speed continuous rolling mill characterized in that a tension difference is applied to the material to be rolled from the tension difference adding device to the inlet side of the second rolling point by reducing the tension. 3. In claim 1, the tension difference adding device is equipped with a tension detection device for the rolled material, and the tension value in the tension difference adding device is determined according to the detected value from the tension detector. A continuous rolling mill with different circumferential speeds, characterized in that it is controlled. 4. According to claim 1, the roller of the tension difference adding device is equipped with a speed detector, and the roll is controlled in accordance with a detected value from the speed detector. rolling machine. 5. In claim 1, a plurality of the rolls are provided, and the tension difference is applied along the route of the rolled material from the first rolling point to the second rolling point of each of the plurality of rolls. A continuous rolling mill with different circumferential speeds, which is characterized by the installation of a device.