JPS5947602B2 - Strip steel rolling method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cold rolling steel strips and an improvement in its equipment.

Hereinafter, a method for skin pass rolling of a thin steel plate (0.3 mm or less), particularly an original plate for a surface-treated steel plate such as tinplate or tin-free steel (hereinafter referred to as TFS), will be described as an example.

The original plate for surface-treated steel sheets such as tinplate and TF8 is JIS G.
The classification standard is divided into 12 levels as specified in 3303 and Al5I.

In order to obtain raw sheets with various degrees of heat treatment, the contents of carbon, nitrogen, phosphorus, manganese, etc. are adjusted in the steelmaking process, the hot rolling finishing temperature and coiling temperature are controlled, and the cold rolling In the subsequent annealing process, the temperature and time relationship are adjusted, and means for controlling the growth of crystal viscosity and the amount of solid solute carbon and nitrogen are performed singly or in combination, and this material is temper-rolled to produce various properties. An original plate with a heat treatment degree of .

However, when temper rolling is used in this way, the composition adjustment at the steelmaking stage and the temperature control during rolling and annealing are complex and diverse, resulting in decreased productivity and increased production costs, making production management extremely difficult. There is a problem that it becomes difficult.

Generally, temper rolling is performed for the following purposes.

That is, the four items are (a), concealment of yield point elongation (stretcher strain) (b), shape correction (e), adjustment of surface roughness (d), and adjustment of surface hardness.

Among these, (b) shape correction and (ω) adjustment of the surface hardness are the most important issues for tin plate blanks, (a) concealment of yield point elongation and (e) adjustment of surface roughness are the most important issues. A normal two-stand skin pass rolling mill as shown in Fig. 1 is in almost satisfactory condition.

In other words, the yield point elongation can be eliminated by adding a rolling reduction of about 1 inch, and the surface roughness can be arbitrarily adjusted by selecting the roughness of the work roll.

Figure 1 shows a conventional 4-high, 2-stand temper rolling mill, where 8 is a payoff reel, 9 is an entry tension pry roll, 9' is an exit tension pry roll, 10 is a tension reel, 3 is a steel strip, 11 , 11' is a stand.

The tension at the rear of the steel strip 30 entrance stand is adjusted by the entrance tension pry roll 9, and the tension at the front of the exit stand is adjusted by the exit tension pry roll 9'.

In this way, the tension pry rolls 9, 9' apply only tension to the steel strip 3.

The steel strip 3 is then rolled while being subjected to tension between the stands 11 and 11', and wound onto the tension reel 10.

Figure 2 is an example showing the relationship between temper rolling reduction and hardness after punch furnace annealing of 0.242 mm thick rimmed steel.As the rolling reduction increases, the hardness after plating also increases in proportion. It can be seen that it increases almost linearly.

Therefore, if the skin pass rolling reduction ratio can be arbitrarily selected and the desired hardness can be stably ensured, the troublesome management during the above-mentioned production process can be considerably simplified.

However, since the thickness of tin plate and TFS is thinner than that of ordinary cold-rolled thin sheets, dry rolling without the use of ordinary lubricants or roll cooling water, such as the one shown in Fig. 1 with a work roll diameter of When dry rolling is performed in a two-stand temper rolling mill, the actual situation is that despite the high intermediate tension, roll flattening is large, so that only a reduction of about 1.5 rounds can be applied.

In this current dry skin pass rolling method, the control range of surface hardness is extremely small and a desired value cannot be obtained, making it impractical.

Therefore, in order to obtain a large reduction in cold rolling, it is important to interpose a lubricant between the roll surface and the thin steel sheet surface to reduce the friction between the two surfaces. It is called and has been practiced for a long time.

Therefore, it may be possible to apply this method to tinplate or TFS, but in this case the following problems arise.

When performing wet rolling at a desired rolling reduction ratio during temper rolling, the material is extremely thin and annealed with a large elongation at yield point, so it can withstand slight fluctuations in rolling pressure and tension.
A so-called jumping phenomenon occurs in which the rolling reduction ratio changes rapidly in the range of 1 to 6 inches, making it difficult to stably secure an arbitrary rolling reduction ratio.

Furthermore, due to this jumping phenomenon, the reduction rate is 1 to 6.
In this range, it was not possible to adjust the rolling reduction ratio, and it was not possible to continuously obtain a desired rolling reduction ratio.

In view of the above facts, this invention was made for the purpose of increasing the range of reduction in skin pass rolling and expanding the range of hardness adjustment. By configuring the speed and relative position thereof to be variable and performing tension bending rolling in this priddle roll, the degree of tempering is controlled and the shape is corrected.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

As shown in FIG. 3, the lower roll 2 is rotated by a roll speed control device (not shown) at a circumferential speed vl higher than the circumferential speed Vo of the upper roll 1, and the steel strip 3 is rotated in the circle of the lower roll on the exit side. It is wound around the upper and lower rolls 1 and 2 so that the circumferential velocity vl is equal to the circumferential velocity Vo of ten rolls on the entry side.

Therefore, by passing between the pair of rolls, the steel strip 3 is extended from the circumferential speed Vo of the upper roll to the circumferential speed vl of the lower roll.

In other words, - during this period, the plate thickness changes from the inlet side plate thickness ho to the outlet side plate thickness h
The thickness is reduced to 1 = ho-VO/Vl.

At this time, the desired exit plate thickness is freely adjusted by a roll speed control device and a roll position variable device (not shown).

In this rolling state, the so-called neutral points of rolling are located at the inlet and outlet of the roll bite, making it possible to escape from pressure increases due to frictional force between the rolls and the rolled material.

As a result, compared to normal rolling, it becomes possible to obtain a large elongation with a small rolling load, and at the same time, the shape of the steel strip becomes very good due to the tensile bending effect, which is the same as that of a tension reel.

If such tension bending rolling is applied to the tension prydle rolls 9 and 9' shown in Fig. 1, the elongation of the tension prydle rolls will be added to the elongation of the conventional rolling mill, expanding the control range of surface hardness and improving the soil strength. Process management becomes much easier.

For example, the prydle rolls 4, 4' of the present invention as shown in FIG. 4A are installed at the front and rear of the conventional cold reverse rolling mill shown in FIG.
If tension bending rolling is carried out, rolling will be performed three times in one pass, and instead of the usual 5 to 6 passes from a hot-rolled coil to a cold-rolled coil, it will be completed in just 2 passes. , greatly improving efficiency.

Further, FIG. 5 shows an application example of a 30-roll tension pry roll, and FIG. Proximity points A and B to left and right rolls 6.7
This shows a state in which the steel strip 3 is subjected to tension bending rolling using a rolling blade.

Furthermore, the invention is not limited to rolling lines, but can also be applied to, for example, plidle rolls on tension level lines.

For example, the main purpose of tension reels is usually shape correction, but if tension leveling is performed directly on annealed material, surface defects called chilimen marks will occur, so temper rolling is required as a pre-process to eliminate elongation at yield point. Met.

Therefore, if this invention is applied to the entry side priddle roll of a tension reel, the yield point elongation will be eliminated by tension bending rolling on the input side priddle roll, and it will be possible to directly tension level the annealed material, which is not possible with the conventional adjustment method. The quality rolling process can be omitted.

Although the present invention has been explained by taking as an example the temper rolling of ultra-thin tinplate and TFS original plates, it goes without saying that it is not limited to this and can be applied to the rolling of any metal.

As mentioned above, this invention applies tension bending rolling using tension pry rolls to impart plastic elongation to the steel strip and at the same time allows for shape modification.This invention simplifies complex production management and improves productivity. It is possible to improve the performance and reduce production costs.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional 4-stage 2-stand temper rolling mill, Fig. 2 is a chart showing the relationship between temper rolling reduction and hardness, and Fig. 3 is a diagram showing the relationship between the temper rolling reduction ratio and hardness. Explanatory drawings showing the principle. Fig. 4 a is a schematic diagram showing a normal cold reverse rolling mill, b is a schematic diagram showing the installation of the priddle roll capable of tension bending rolling of the present invention, and Fig. 5 a is a schematic diagram showing a normal cold reverse rolling mill. Fig. 3 is an explanatory diagram showing a 30-ru roll of a tension pry roll, and b is an explanatory diagram showing a 30-ru roll of tension bending rolling according to the present invention. 1...Top roll, 2...Bottom roll, 3
... Steel strip, 4 ... Prydle roll of this invention, 5 ... Intermediate roll, 6.7 ...
...Roll, 8...--Payoff reel, 9...
・・・Entrance side tension pry roll, 9′...
・・Exit side tension pry roll, 10・・・・
・Tension reel, 11...Stand, VO
......Top roll circumferential speed, vl...Bottom roll circumferential speed, ho...Enter side plate thickness, h
...Exit side plate thickness, A. B... Proximity point.

Claims (1)

[Scope of Claims] 1. In a strip steel rolling line having tension prydle rolls, the rotational speed and relative position of each of the prydle rolls are made variable, and the rotational speed and rolling reduction of the prydle rolls are controlled. 1. A method of rolling a steel strip, characterized by carrying out tension bending rolling. 2. In a strip steel rolling line having tension prydle rolls, a roll speed control device that can freely change the rotational speed of each of the prydle rolls, and a roll position variable device that can freely change the relative position of each of the prydle rolls, A strip steel rolling device characterized by controlling the reduction of a priddle roll and performing tension bending rolling with the priddle roll.