JPH0623402A - Method and mill for rolling - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rolling apparatus with a low probability of breaking a roll without changing the characteristics of the rolled material. [Structure] Heating devices 17 and 18 for heating the rolling rolls are provided near the rolling rolls 7 and 12, respectively. [Effects] By raising the temperature of the rolling rolls 7 and 12 by the heating devices 17 ..., 18 ..., The temperature can be made approximately the same as the temperature of the rolling member, and the temperature difference between the rolling roll and the rolled material The resulting thermal stress does not occur in the rolling roll, and damage to the rolling roll can be prevented. Also,
The characteristics of the rolled material are not changed without causing variations in dimensions, characteristics, etc. of the rolled material between the first rolling treatment and the second and subsequent rolling treatments.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling method and a rolling apparatus for rolling a member to be rolled such as a wire rod or a plate material, and more particularly to a method and an apparatus capable of reducing the probability that a rolling roll is damaged.

[0002]

2. Description of the Related Art As an example of a conventional rolling mill, a two-stage rolling mill as shown in FIG. 2 is known.

This figure shows a state in which a member to be rolled such as a plate material is rolled into a rolled material 1 having a thickness T. Reference numeral 2 in the drawing denotes an upper part of the housing of the rolling mill, and the upper part 2 of the housing is provided with rods 3a and 3b which can be expanded and contracted in the vertical direction by hydraulic means or the like. Upper chocks 4 and 5 are fixed to the tips of the rods 3a and 3b, and an upper roll 7 rotatably fixed to a shaft 6 is attached between the upper chocks 4 and 5. Further, lower chocks 9 and 10 are fixed to the lower portion of the housing shown by reference numeral 8, and a lower roll 12 rotatably fixed to a shaft 11 is attached between the lower chocks.

In order to perform a rolling operation using the rolling apparatus having the above-mentioned structure, first, the rods 3a and 3b are moved downward to hang down the upper roll 7, and then between the upper roll 7 and the lower roll 12. The rolled material 1 having a predetermined thickness T is formed by continuously moving the member to be rolled and performing the rolling process.

At this time, the pressure during rolling is adjusted by changing the moving positions of the rods 3a and 3b and adjusting the position of the upper roll 7.

[0006]

The member to be rolled in the above apparatus is heated by a heating furnace or the like to a temperature of about 800 to 1200 ° C., and the upper roll 7 and the lower roll 12 are rolled. Although it is conveyed in the meantime, if the first rolling is performed under this condition, the rolling roll may be damaged.

It has been found that most of this damage occurs in the first rolling treatment step, and almost no damage occurs after passing the member to be rolled several times between the rolling rolls.

For this reason, it is also practiced to prevent the roll from being damaged by performing the first rolling step under a light pressure. But,
In this case, the dimensions of the rolled material during the first and subsequent rollings,
There may be variations in characteristics and the like.

Therefore, as a result of detailed examination of the cause of roll damage, the present inventors found that this damage was caused by thermal stress caused by the difference between the surface temperature of the rolling roll and the central temperature of the rolling roll. It was

That is, in the first rolling step, the temperature of the member to be rolled is about 800 to 1200 ° C.
Since the temperature of the rolling roll is room temperature, the difference between the roll surface temperature and the central temperature during rolling is very large, and the rolling stress is damaged by the thermal stress generated by this temperature difference, causing cracks. However, after passing the member to be rolled between rolling rolls several times, the heat of the member to be rolled is transferred to the rolling roll and the temperature of the rolling roll rises to about 150 to 300 ° C., so that the temperature of the surface and the central portion is increased. It has been found that the difference is small and the thermal stress generated is small and cracks are less likely to occur.

[0011]

The present invention has been made based on the above-mentioned findings, that is, in the rolling method according to claim 1, the rolling roll is set to a predetermined rolling length at the time of the first rolling or prior to the first rolling. Heating to temperature was the means for solving the problem.

In the rolling apparatus according to the second aspect, a means for solving the problem is that a heating device for heating the rolling roll is provided in the vicinity of the rolling roll.

[0013]

When the rolling device is heated by the heating device at the time of the first rolling or before the first rolling by the rolling device provided with the heating device in the vicinity of the rolling roll, the temperature (central portion) of the rolling roll and the member to be rolled Since it is possible to reduce the difference in the temperature (roll surface temperature) of the rolling roll, a large thermal stress due to the temperature difference between the rolling roll (central portion) and the member to be rolled (surface) may occur in the rolling roll. Absent.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rolling method and rolling apparatus of the present invention will be described in detail below with reference to the drawings. The same components as those of the conventional example are designated by the same reference numerals to simplify the description.

FIG. 1 is a schematic diagram showing an embodiment of the rolling apparatus of the present invention. This drawing shows a state in which a member to be rolled such as a plate material is rolled into a rolled material 1 having a thickness t, and the housing upper portion 2 can be vertically expanded and contracted by hydraulic means (not shown) or the like. Lower rods 9a and 10b are fixed to the lower portion 8 of the housing and the lower rod 8 of the housing, and a lower roll 12 rotatably fixed to a shaft 11 is mounted between the lower chocks. This is the same as the conventional device.

In the apparatus of this embodiment, upper chocks 15, 16 connected to each other by a connecting portion 13 are further fixed to the tips of the rods 3a, 3b. An upper roll 7 rotatably fixed to the shaft 6 is attached between the tip portions of the upper chocks 15 and 16. The burner 1 for heating the upper roll 7 is provided on the upper roll 7 side of the connecting portion 13.
7 ... are provided.

Burners 18 for heating the lower roll 12 are attached to the lower portion 8 of the housing.

The burners 17, ..., 18 ... Are connected to an ignition device and a heat power adjusting device (not shown) so that they can be freely ignited from the outside and the amount of the flame 19 can be adjusted.

Although the number of burners 17 and 18 is four in FIG. 1, it is needless to say that the number is not limited to this number.

In order to perform the rolling operation by the rolling apparatus having the above-mentioned structure, first, the upper rolls 7 and the lower rolls 12 are heated to predetermined temperatures by the burners 17 ..., 18 ... And the rods 3a, 3b are moved downward. Then, the upper roll 7 is hung down, and then the material to be rolled is moved between the upper roll 7 and the lower roll 12 to perform a rolling treatment, whereby the rolled material 1 having a predetermined thickness t is formed.

When the first rolling of the rolled material 1 is completed, the ignition device (not shown) is turned off to extinguish the flame 19, the heating of the rolling roll is terminated, and the material to be rolled is continuously moved to perform the rolling treatment. .

By performing the first rolling treatment while heating as described above, it is possible to reduce the temperature difference between the material to be rolled (roll surface) and the rolling roll (central portion). It is possible to prevent the occurrence of thermal stress due to, and to reduce the amount of cracks generated in the rolling roll.

In the method of the present embodiment, the heating of the rolling roll was completed in the second and subsequent rolling treatments. However, the temperature of the rolling roll was lowered by adjusting the ignition device to reduce the amount of flame. You can go. Further, the rolling roll may be preheated before the first rolling treatment. In this case, the temperature of the rolling roll can be lowered when the rolling roll reaches a predetermined temperature.

(Experimental example) As shown in Table 1, when the material of the roll, the heating temperature of the roll by the burner, and the temperature of the material to be rolled were set, the presence or absence of cracks in the rolled material was examined. As a method for evaluating the presence or absence of cracks, the surface was polished with emery paper # 800, the surface was etched with an acid solution, and then the surface crack was measured with a magnifying glass, and the crack length was 0.5.
None if less than mm, medium 2 m if 0.5-2 mm
When it exceeded m, it was considered large.

The results are shown in Table 2. As a comparative example, the results when not heated with a burner are also shown. Margin below

[0026]

[Table 1]

[0027]

[Table 2]

From the above results, it was found that the generation of cracks can be suppressed by heating the roll with a burner to reduce the temperature difference between the surface and the central portion of the rolling roll.

[0029]

As described above, the rolling method of the present invention is characterized in that the rolling roll is heated to a predetermined temperature during the initial rolling or prior to the initial rolling. Since it is possible to reduce the difference in temperature (surface) between the central portion) and the member to be rolled, thermal stress due to the temperature difference between the surface of the rolling roll and the central portion does not occur in the rolling roll.

Therefore, according to the rolling method of the present invention, the rolled material can be made uniform without changing the dimensions, characteristics, etc. of the rolled material between the first time and the second time and thereafter without changing the characteristics of the rolled material. The probability of damaging the can be reduced.

Further, in the rolling apparatus of the present invention, since the heating apparatus for heating the rolling roll is provided in the vicinity of the rolling roll, the temperature of the rolling roll is increased and the temperature difference with the rolling member is reduced. Can be made smaller.

Therefore, when the rolling treatment is carried out using the rolling apparatus of the present invention, the thermal stress caused by the temperature difference between the surface of the rolling roll and the central portion does not occur in the rolling roll, and the rolling roll is prevented from being damaged. can do.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a rolling device of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional rolling apparatus.

[Explanation of symbols]

 1 Rolled material (rolled member) 7 Upper roll (rolling roll) 12 Lower roll (rolling roll) 17 Burner (heating device) 18 Burner (heating device)

Claims (2)

[Claims] 1. A rolling method comprising heating a rolling roll to a predetermined temperature at the time of first rolling or prior to the first rolling. 2. A rolling device comprising a heating device for heating the rolling roll in the vicinity of the rolling roll.