JPH02182301A - Method for rolling - Google Patents

Abstract

PURPOSE:To prevent a stock from lapping by bringing an idle roll in the downstream side to be movable in a nearly orthogonal direction to the stock passing plane, pushing the roll below the stock passing plane by a pushing amount based on a rolling condition, and winding the stock onto a rolling roll over a prescribed angle range. CONSTITUTION:A rolled stock deforms into a V shape between a rolling roll and an idle roll in the upstream side and is pushed over a wide region of the peripheral surface of the rolling roll by pushing a downstream side idle roll 2b onto the stock. By this, waviness of the stock caused by insufficient flatness of the stock is absorbed in that region and the stock is prevented from meandering and lapping. A winding angle necessary to prevent lapping varies with rolling conditions, such as a stock size and a rolling speed. Lapping is completely prevented by giving a push-in amount according to rolling conditions to the idle roll in the downstream side. Hence, damage to the stock and equipments, such as the rolling roll is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rolling method for preventing material squeezing into rolling rolls.

[Prior Art] Hot-rolled steel sheets manufactured by hot rolling are affected by uneven rolling reduction in the width direction of the sheet, uneven cooling after rolling, etc., and therefore have low flatness. Therefore, it is customary for hot rolled steel sheets to be lightly rolled down by cold skin pass rolling after hot rolling to improve flatness.

In this skin pass rolling, narrowing down of the material to the rolling rolls has traditionally been a problem. This is a phenomenon in which the material is folded and bitten by the rolling rolls, and is caused by meandering and waving that occur when rolling a material with low flatness, and the faster the rolling speed, the more likely it is to occur. When this squeezing occurs, not only the material is damaged and becomes scrap, but also rolling equipment such as rolling rolls is damaged, and recovery thereof requires a great deal of expense. Therefore, prevention of squeezing is considered one of the most important issues in skin pass rolling.

To prevent squeezing during skin bath rolling,
As shown in Fig. 4, an idle roll 2 called a crimp roll is provided below the material passing surface on the inlet side of the rolling roll 1, and is positioned above the normal material passing surface level to apply tension to the material 3. It is common practice to add

(Problems to be Solved by the Invention) According to this squeezing prevention measure, it is possible to prevent the material from meandering, but it is not possible to prevent the material from waving, and therefore squeezing cannot be completely prevented. It is essential to perform a so-called leveling operation in which a worker on the side constantly monitors the running status of the material and adjusts the amount of rolling left and right of the rolling rolls depending on the running status.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling method that completely prevents narrowing, which is a problem in skin pass rolling, etc., by mechanical means, and makes it unnecessary to monitor the material at the entrance of the rolling mill.

[Means for Solving the Problems] The rolling method of the present invention includes arranging idle rolls in two stages in the rolling direction so as to contact the material surface from different sides on the entry side of the rolls, and idle rolls on the downstream side. The idle roll is movable in a direction approximately perpendicular to the material passing surface, and by pushing the downstream idle roll through the normal material passing surface with a pushing amount based on rolling conditions, the material is moved at a predetermined angle on the rolling roll circumferential surface. This is to prevent the material from being squeezed by wrapping it around the area.

(Sakukawa) By pushing the downstream idle roll beyond the normal material passing surface, the material is deformed into a V-shape between the rolling roll and the upstream idle roll, and the material wraps around the rolling roll. In this way, the material is pressed against a wide range of the circumference of the roll.As a result, waving caused by poor flatness of the material is absorbed in this area, and meandering of the material is also prevented by the friction between the rolling roll and the material. As a result, narrowing down can be prevented.

The winding angle at which the material is wound around the circumferential surface of the rolling roll is determined by the amount of pushing of the idle roll on the downstream side. In addition, it has been found from research by the present inventors that the winding angle required to prevent squeezing changes depending on rolling conditions such as material dimensions and rolling speed. Therefore, squeezing can be completely prevented by applying a pushing amount to the downstream idle roll according to the rolling conditions.

〔Example〕

The present invention will be explained in more detail below based on the drawings.

FIG. 1 is a schematic diagram showing the basic concept of the rolling method of the present invention. Upper and lower set of rolling rolls 1. Two idle rolls 2a and 2b are arranged in two stages in the rolling direction on the entry side of the roll roll 1. Roll roll 1. The idle roller 2a on the upstream side away from t is fixed and located below the material passing surface, and its upper edge is brought down to the normal level of the material passing surface. Rolling loaf 1 Idle roller 2 on the downstream side located on the el side
b is located above the material passing surface and is configured to be movable in the vertical direction.

By pushing the idle roll 2b on the downstream side below the regular material passing surface, the material is transferred between the rolling roll and the idle roll 2a on the upstream side. 43 is deformed into a ■ shape, and the material 3 is wrapped around the peripheral surface of the lower rolling roll 1.

At this time, if the pushing amount S from the normal material passing surface of the downstream idle roll 2b is increased, the material wrapping angle θ around the roll circumferential surface becomes larger. The degree of influence of the pushing ls on the winding angle θ increases as the idle roll 2b on the downstream side is brought closer to the rolling roll 1. Therefore, the idle roll 2b and the rolling roll 1. It is best to make the distance between the two shafts as small as possible without interference between the two. Usually, the diameter of the rolling roll 1.1 is D, the diameter of the downstream idle roll 2b is d, and (D + d )
/2≦L≦D+d.

The distance between the axes of the idle rolls 2a and 2b is usually desired to be within the range of d to 4d for the purpose of restraining the material.

The diameters of the idle rolls 2a and 2b are not particularly determined as long as their strength can be ensured.

Figure 2 shows the occurrence of squeezing when skin-pass rolling a material with a width of 1250 ma+ and a thickness of 1.6 tm, and the wrapping angle θ and rolling speed when the material is wrapped around the circumferential surface of the rolling roll using the above method. This is a chart showing the relationship between The rolling roll diameter is 600 mm, the idle roll diameter d is 200 m11 for each roll, the distance between the rolling rolls and the idle roll on the downstream side is 600 ai, the distance between the shafts between the downstream idle roll and the upstream idle roll. is set to 550■.

When the rolling speed is 100 mρm, squeezing is prevented when the wrap angle θ is about 10 degrees or more, and when the rolling speed is 250 mpm, squeezing is prevented when the wrap angle θ is about 20 degrees or more. The critical value of the wrap angle θ at which squeezing can be prevented increases as the rolling speed increases, and the relationship between the two is uniquely determined by material dimensions, roll dimensions, positional relationship of the rolls, and the like.

In the rolling method of the present invention, this relationship is determined in advance for various rolling conditions from past operating results (.

Then, from among them, the relationship regarding the rolling conditions to be performed is extracted, and the indentation IS of the idle roll on the downstream side is determined so that the above-mentioned critical value shown in the relationship is secured, and rolling is performed. . By doing so, the squeezing of material into the rolling rolls, which is a problem in skin pass rolling, etc., is completely eliminated. As described above, prevention of this squeezing is achieved by preventing the material from meandering by wrapping the material over a wide range around the circumferential surface of the rolling roll, and by absorbing undulation.

In FIG. 1, the upstream idle roller 2a is located below the material passing surface, and the downstream idle roller 2b is located above the material passing surface.
may be located above the material passing surface, and the downstream idle roller 2b may be located below the material passing surface. In that case, the downstream idle roller 2b is pushed above the regular material passing surface, and the upper Roll roll! Material 3 will be wrapped around it.

A well-known structure can be adopted as the means for pushing the idle roll 2b on the downstream side, and the specific structure is not limited. FIG. 3 shows an example of a pushing structure for pushing the idle roll 2b upward. The idle roll 2b is attached to the tip of a single-work arm 52 which is pivotally supported by a pin 51 on the frame at an intermediate portion. 1! The base end of the movable arm 52 comes into contact with a roll height adjustment jack 53 from above. (The tip of the two-motion arm 52 is connected to the cylinder 5.
4, the idle roll 2b is pushed upwards from the normal material passing surface, and the two moving arms 5
It is fixed at the place where the base end of 2 abuts against the jack 53.

Note that the method of the present invention is not limited to skin pass rolling, and can be applied to other types of rolling where there is a risk of reduction.

〔Effect of the invention〕

The rolling method of the present invention completely prevents squeezing, which is a big problem in skin pass rolling, etc., by mechanical means.

Therefore, not only damage to the material due to squeezing and damage to equipment such as rolling rolls is prevented, but also material monitoring at the entrance of the rolling mill is no longer required, streamlining the rolling operation, and the combined effect of these efforts reduces rolling costs. Significant savings are achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic concept of the rolling method of the present invention, FIG. 2 is a chart showing the degree of influence of the winding angle and rolling speed on squeezing, and FIG. 3 is a side view showing the idle roll pushing structure. FIG. 4 is a schematic diagram showing a conventional narrowing down measure. In the figure, 1: rolling roll, 2: idle roll, 3: material. Figure Figure

Claims (1)

[Claims] 1. Idle rolls are arranged in two stages in the rolling direction so as to contact the material surface from different sides on the entry side of the rolling rolls, and the idle rolls on the downstream side are arranged against the material passing surface. By pushing the idle roll on the downstream side from the regular material passing surface with a pushing amount based on the rolling conditions, the material is wrapped around a predetermined angular range on the circumference of the rolling roll and narrowed down. A rolling method characterized by preventing. 2. The rolling method according to claim 1, characterized in that the pushing amount of the idle roll on the downstream side is determined based on the relationship between the material wrapping angle and the occurrence of squeezing determined from past actual operation results. .