JPH04279204A - Sleeve roll with caliber for three roll mill which has large effective diameter using for rolling - Google Patents

Abstract

PURPOSE:To reduce the number of reserved rolls and frequency of roll change and to improve the productivity by providing hardness difference that the hardness on outer peripheral side of sleeve layer is higher and making the effective diameter using for rolling larger in a sleeve roll with caliber for three roll mill. CONSTITUTION:This roll is a step-type sleeve roll 7 which the interior of sleeve 8 layer of the sleeve roll 7 with caliber for three roll mill is made of the layer of high harness 1, medium harness 2 and low hardness 3 in the order from the outer peripheral side and made into a structure which is provided with hardness difference in the sleeve layer. And it is used adjusting to proper hardness while grinding it to a fine diameter for the material of high hardness 1, to a large diameter for the material of low hardness 3 and to a intermediate diameter of wire for the material of medium hardness 2. Thus, the range that continuous rolling without changing roll is possible with a three roll mill is extended by using a roll which has a large effective using range for rolling, so productivity is improved by reducing the number of reserved rolls and decreasing the frequency of roll change.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grooved sleeve roll for a three-roll rolling mill for rods and wire rods.

0002

BACKGROUND OF THE INVENTION Rolling of rods and wire rods is carried out in horizontal and vertical rolling mills using a pair of rolls provided with a caliber.
P. of the 50th Small and Medium Size Subcommittee Special Lecture [On Trends in Rolls for Long Steel Rolling] of the Japan Iron and Steel Institute. 66 “Table 15 - Trends in Rolls for Rolling Long Steel” and “Chijinshokan Japan Iron and Steel Institute Edited Edition Steel Technology Course Volume 2 Steel Manufacturing Methods”
P. 168(e), the roll material and roll hardness are classified according to rolling characteristics, rolling material temperature, rolling speed, and rolling material steel type.

[0003]Recently, in order to cope with higher rolling speeds, lower temperatures of rolled materials, and high-load rolling, in rolling rolls for finishing mill groups, even within the same finishing rolling mill group, finishing upstream rolling mills have been used. The materials used for the rolls are selected separately for the rolling mill rolls, the rolling rolls for the finishing midstream rolling mill, and the rolls for the finishing downstream rolling mill. For example, even with the same rolling roll for a finishing mill, if the rolled material is a small diameter material of 20 mm or less and the rolling speed is high, alloy chilled rolls or superalloy W
When a C roll is used and the rolling speed is relatively slow, such as when the material to be rolled has a diameter of 60 mm or less, ductile cast iron rolls are used to differentiate the roll material used even in the same finishing mill. In addition, the classification of roll materials, etc. in this finishing rolling mill group is the same when rolling rods and wire rods in a 3-roll rolling mill, and the roll materials for the 3-way rolling mill are also used depending on the finishing rolling size. The material of the roll is classified.

[0004] As described above, the optimum roll material to be used is limited depending on the rolling conditions, so each rolling roll is used in a limited rolling mill in the bar and wire rod production line, and the next rolling use after the rolling is completed. Even in roll turning for rolling stock, turning is carried out into a roll caliber shape that is compatible with the roll material.

[0005] Regarding the roll structure, a method for manufacturing a composite sleeve for a mill roll with grooves was proposed in Japanese Patent Publication No. 61-5.
No. 4087 and Japanese Patent Publication No. 61-54088 disclose a method of forming a roll into a composite structure of a surface layer and an inner layer in order to prevent cracks caused by shrink fitting when the rolls are fastened. There is no description or suggestion of changing the hardness by changing the material of the surface layer and inner layer of the roll structure based on the rolling characteristics of the target rolled material.

[0006]

[Problems to be Solved by the Invention] As mentioned above, in the case of rolling rolls for two-roll rolling mills and rolling mills for three-roll rolling mills for rods and wire rods, the number of rolls used depends on the rolling mill position and rolling conditions. Because it is necessary to use different roll materials and roll hardness, a large number of rolls, including spare rolls, must be prepared for each rolling mill, depending on the type of caliber shape to be rolled by that rolling mill. Not only that, but where to store the roll when not in use is also a problem.

In the case of two-roll rolling mills for rods and wire rods, most rolling mills can adjust the rolling positions of the rolls 4 and 5 as shown in (a) of FIG. Even if the size is smaller, it is possible to roll the same rolled material size as shown in FIG. 2(b). On the other hand, in the case of a three-roll rolling mill as shown in Fig. 3, it does not have a mechanism for adjusting the rolling position of the rolls that can greatly adjust the amount of movement equivalent to that of two rolls. It is not possible to adjust or change the distance significantly, and the size of the rolled material that can be rolled is limited depending on the roll diameter. The diameter of the roll must be prepared accordingly.

On the other hand, from the viewpoint of the rollable effective diameter of the roll, the material and hardness of conventional rolls do not change significantly from the surface layer to the bottom layer within a single roll, so as shown in FIG. The rolling roll cannot be used in a range other than the roll diameter of the rolling region A to which the roll material is suitable, and the rollable effective diameter of the roll becomes a very small range. In this way, in a three-roll rolling mill, it is customary to mill the rolls without removing them, but if it is not suitable for the material to be rolled, it is necessary to replace it with another roll, and the roll In addition to the increase in the number of machines in stock, the increase in roll changeover time also has a large impact on productivity.

[0009]

[Means and effects for solving the problems] The present invention has been made in view of the above problems, and its gist is to provide a grooved sleeve for a three-roll rolling mill in the hot rolling process of rods and wires. In the roll, the sleeve roll has a grooved sleeve roll for use in a three-roll rolling mill with a large effective diameter for rolling, which has a structure in which the inner hardness of the sleeve layer of the sleeve roll is higher toward the outer circumferential side of the roll.

That is, in a rolling roll for a three-roll rolling mill for rods and wire rods, when the roll diameter is large, the roll material is made of a roll material suitable for rolling small diameter materials, and the roll hardness is set in the large diameter region of the roll effective diameter, and when the roll diameter is small, the roll material is made of a material suitable for rolling small diameter materials. The roll material is made to be suitable for rolling materials.The roll hardness is set in the small diameter area of the roll effective diameter, and the roll material in the middle area is made to be suitable for rolling small diameter materials.The roll hardness is made to be suitable for rolling large diameter materials. This rolling roll is characterized by having a hardness distribution that shifts to roll hardness.

In this way, the present invention replaces the use of rolls classified by roll material and so-called hardness according to the rolled wire diameter as described above, by imparting hardness differences within the sleeve layer of one roll itself. The effective rolling diameter has been increased, and the number of rolls that were conventionally required can be significantly reduced.

FIG. 1 schematically shows an embodiment of the present invention. The diagram in (a) of the same figure shows that the inner layer of the sleeve 8 is made of a material whose hardness gradually decreases from the outer circumferential side, for example, a hardness gradient type in which a cast iron roll is made of a chilled material with high hardness and a grain material with low hardness. It is a sleeve roll,
The hardness distribution image at that time is shown in the figure (b). In addition, the diagram (c) in the same figure shows a step-type sleeve roll in which 8 layers of the sleeve are stacked in layers for each material of each hardness, with high hardness 1, medium hardness 2, and low hardness 3 from the outer peripheral side, For example, a cast iron roll has a structure in which hardness differences are given within the sleeve layer by using a chilled material for high hardness, a grain material for medium hardness, and a ductile material for low hardness. The hardness distribution image at that time is shown in the figure (d). (b), (
In the high hardness part 1 in figure d), small diameter material (e.g. 20mmφ) is used.
(below), the low hardness part of 3 is a large diameter material (e.g. around 60mmφ), and the medium hardness part of 2 is a material with an intermediate diameter (e.g. 35mm).
These are the respective ranges that are used depending on the appropriate hardness while machining the material (around mmφ).

[0013] The relationship between the diameter of the rolled material and the roll hardness (material) is determined by rolling characteristics such as the steel type, rolling temperature, and rolling speed of the rolled material, but as a general tendency, Rolls are suitable for small-diameter materials because they have good surface quality, and rolls made of low-hardness materials have an advantage in heat cracking resistance, so they are used for large-diameter materials that require high rolling temperatures. is customary.

[0014]

[Example] Two 3-roll rolling mills shown in Fig. 3 were installed in the well-known steel bar hot rolling process, and only the finish rolling mill group was used to process materials equivalent to the JIS S45C standard using the slotted sleeve rolls of the present invention. 10mmφ, 30mmφ, 40mmφ, 70
Steel bars of mmφ were rolled, and the amount of rolling at each rolling size was investigated. The limit of the amount of rolling for each size is the dimensional tolerance range for each size specified in JIS, and when the tolerance is reached, the material is turned to the hole size of the next rolled material size on the line without removing the roll. The grooved sleeve roll of the present invention used is shown in FIG. 1 (a
) is a cast steel roll made of a material with a gradient type of hardness change within the sleeve layer, and its composition is shown in Table 1.
As shown in The table also shows the finish rolling temperature for each rolling size.

[0015]

[Table 1]

The results of the investigation are also shown in Table 1. With one type of roll of the present invention, it was possible to roll a steel bar for a total of 960T, from 200T at 10 mmφ to 300T at a final diameter of 70 mm. This amount of rolling is comparable to conventional rolls, but if this implementation condition is carried out using conventional rolls, four types of rolls for each rolling size must be used, which increases the number of roll changes and reduces production efficiency. I will invite you.

[0017]

Effects of the Invention: The rolls of the present invention, which have a large rolling range, have expanded the range in which continuous rolling can be performed in a three-roll rolling mill without having to rearrange the rolls, which has led to a reduction in the number of rolls in stock and the number of roll rearrangements. This greatly contributes to improving productivity by reducing

[Brief explanation of the drawing]

FIG. 1 schematically shows an example of the structure of the material inside the sleeve layer of the sleeve roll for a three-roll rolling mill according to the present invention, and (a) in the same figure is a structural diagram of the material in which the hardness difference is graded. (
(b) is an image diagram of the hardness distribution of the slope type, (c) of the figure is a structural diagram of the material with the hardness difference as a staircase type, and (d) is an image diagram of the hardness distribution of the staircase type.

FIG. 2 is a diagram illustrating the roll diameter and rolling reduction adjustment in a two-roll rolling mill.
b) is a diagram showing the position of each roll when the roll diameter is small.

FIG. 3 is a schematic diagram showing an example of the structure of a three-roll rolling mill.

FIG. 4 is a diagram illustrating a conventional sleeve roll for a three-roll rolling mill.

[Explanation of symbols]

1 High hardness part of small diameter rolled material 2 Medium hardness part of medium diameter rolled material 3 Low hardness part of large diameter rolled material 4 2nd roll upper work roll 5 2-roll lower work roll 6 Rolled material 7 3-roll rolling roll 8 Sleeve

Claims (1)

[Claims] 1. A slotted sleeve roll of a three-roll rolling mill used in the hot rolling process of rods and wires, wherein the hardness within the sleeve layer of the sleeve roll has a hardness difference that is higher toward the outer periphery of the roll. Sleeve roll with hole pattern for 3-roll rolling mill with large effective rolling diameter.