JPS6018484B2 - A rolling roll with a strong neck part and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composite roll having a new structure that is most suitable for a rolling roll having a special shape and usage characteristics, such as an elongated neck shape and particularly requiring strong rut resistance at the neck end. and the provision of its manufacturing method.

The rolling roll is composed of a body part and a neck part, and the body part is formed of eight outer shell parts and a core part which is integrally cast concentrically with the outer shell parts, and The neck portion is formed by a bearing portion integrally cast with the torso core portion on both sides of the torso core portion, and a neck end portion integrally cast on both sides of the bearing portion. Because the properties required for rolling are different, composite rolls in which the outer shell, core, and neck are made of different materials are often used; however, in recent years, hot strip mills for rolling steel plates have been developed to Therefore, new formats are being researched and developed.

In other words, these are works. These methods include a method of shifting (moving) a roll in the axial direction, a method of forcibly suspending a work roll, and a method of crossing two work rolls with respect to a back-up roll. Therefore, work rolls used in these rolling methods tend to have smaller body diameters. Furthermore, due to the type of rolling mill, the length of the neck needs to be longer than that of the follower roll, and the diameter of the neck is also made smaller. In addition, in this type of roll, greater stress is generated in the neck portion than in the past, and particularly strong rutting resistance is required. The conventional general shape roll is shown in Figure 1, and the special shape roll used for the above new rolling method is shown in Figure 2 in comparison, and the specific differences in shape and dimensions are summarized as follows. . Buddha N nefu-necessary B DN
Mutsushin NDB conventional loo.

1400 0.52~〇. 75 34o~5oo
2. o~3.6 650~840 roll shape characteristics
Special ・500 to 2000 0.80 to 1.2o
13o~33o 3.8~130 500~760
Roll shape N: Neck length (skin) B: Neck length (skin) DN: Neck end diameter (skin) DB: Body diameter (skin) As mentioned above, the roll used for this new rolling method has the following properties:
Generally, the neck length to body length ratio IN/IB is 0.8 to 1.2, or the neck length to neck diameter ratio IN/DN is 3.8 to 13.
It is characterized by having an elongated neck shape in which one or both of the neck ends has a smaller diameter than the bearing part.

By the way, the usage characteristics of the ear portion and the neck portion as a whole are also different for such specially shaped rolling rolls, and as shown in Fig. 3, the ear portion 1 in contact with the rolled material has wear resistance. , roughness resistance, crack resistance, etc. are required.
On the other hand, the characteristics required for the neck part differ depending on the part in the rutting direction.The bearing part 2, which is close to the body part 1, requires wear resistance and toughness against friction with the bearing, while the neck part, which is far from the body part 1, requires abrasion resistance and toughness. Part 3 is elongated in shape and requires particularly strong balling properties since it needs to withstand large stress. In addition, in this specially shaped roll, as shown in FIGS. 2 and 3, there is a part of the neck end 3 that is longer in diameter than the neck end DN, and depending on the rolling method, for example, the working side W A large thrust stress is generated on the drive side D, and a large shift stress is generated on the drive side D, so this part requires particularly strong strength. The present invention thus provides an elongated neck shape in which the neck length to body length ratio IN/]B is 0.8 to 1.2 or the neck length to neck diameter ratio IN/ON is 3.8 to 13.0. The outer shell is made of adamite or alloyed cast iron, 8 concentric parts, and bearings are used for special rolling rolls in which large stress occurs at the neck end. The present invention provides a composite roll having a new roll structure in which the neck end is made of spheroidal graphite cast iron and one or both of the neck ends are made of high-grade steel and the three parts are welded together. This provides a suitable manufacturing method.

Among the composite work rolls conventionally used in hot strip mill finishing stands, those for the front stand are:
Generally, Adamite material and high chromium material are used for the outer shell of the body.

In addition, high-alloy grain material is generally used for the latter stage. On the other hand, high-grade cast iron or ductile cast iron is used for the core of these subordinate rolls. The chemical components and properties of conventional composite roll materials are listed below. Chemical components (wt mass) C Si Mn Ni Cr M.

Mg Hardness Tensile Strength Elongation (Hs) (Ktafoam. (Outer shell) Adamite material 1.2~2.8 0.3~
1.0 0.5"1.5 2.0 or less 0.5"3.0
0.2~1.0 - 45/65 station chromium material 2
．． 0 and 3.2 0.5 to 1.5 0.5'' 1.5 0.
5~2.0 10・25 0.2~3.0 -
60~80 High Alloy Clearance Material 2.8" 3.5 0.5~
1.5 0.5・12 3.5~5.0 1.0・2.
5 0.2~0.6 - 70~85 (core material) High grade cast iron 2.8" 3.7 0.5~1.5 0.
4~1.2 03''15 0.3・1.0 0.2 or less ・-40~50 20''30 0.1~0.3
Tactile cast iron 3.0・3.8 1.5~2.5 0
．． 4-1.0 2.0 or less 0.4-1.0 0.2 or less 0.03 or more 40-50 40・50 0.5-
1.0 However, as a result of intensive research by the present inventors, when the subordinate composite roll is applied as it is to the roll for the shape intended by the present invention, the strength at the neck end is insufficient and the result is that However, it was found that it was not usable.

That is, in the case of high-grade cast iron, it clearly lacks strength as shown in the table above, and even in the case of ductile cast iron, it still lacks strength when used for necks with long and narrow special shapes. In addition, since the neck portion of the rolling roll according to the present invention is long and narrow, after performing far-D force casting of the body outer shell portion as in the conventional method, the centrifugal force casting mold is made into a static folding mold, and the body core portion and the neck portion are cast into a centrifugal force casting mold. In the method of integrally casting the end portion, deep shrinkage cavity-like defects occur at the neck end portion along the roll melt, making manufacturing difficult. Therefore, in the present invention, as shown in FIG. 4, the outer shell portion la is formed of an alloy cast iron material such as the above-mentioned adamite material or Ni grain material, as in the case of the conventional composite roll. The body core part lb and bearing part 2, which require strong balling properties and wear resistance, are made of a specific spheroidal graphite cast iron, and one or both of the neck end parts 3, which require particularly strong toughness, are made of a specific spheroidal graphite cast iron. This is formed from a strong steel material different from that which forms the 8 concentric parts lb and the bearing part 2, and the trunk outer shell part la, the trunk core part lb, the bearing part 2, and the neck are made of different materials. The three end portions 3 are welded and integrated to form a composite roll.

The materials used to form the trunk core part lb, the bearing part 2, and the neck end part 3 are those that are superior in hardness, strength, elongation, etc. to conventional high-grade cast iron, high-grade cast iron, or ductile cast iron.

In other words, the bearing part 2 must also have wear resistance.
A material with higher hardness and strength than conventional high-grade cast iron is required, with a hardness of Hs 40-50 and a tensile strength of 40-55.
K9/rib, made of ductile cast iron material that satisfies elongation of 0.5 to 1.5%. On the other hand, for the neck end 3, strong rutting resistance, especially ballability, is required rather than wear resistance, so the hardness should not be too high, but on the other hand, rotational wear must also be taken into consideration, so Hs30~ It needs to be 45. The tensile strength should be 55k9/m or more, more preferably 65k9/m or more, and elongation 1.5.
% or more. As a material for forming the eight concentric portions lb and the bearing portion 2 that are suitable for such purposes, ductile cast iron having the following chemical components is cited as a suitable material.

Chemical components (wt large) C Si Mn Ni Cr M.

Mg Hardness Tensile Strength Elongation (Hs) Gourd Taiwei) (Omitted) Rishin Sei and Rin 31 Skin/Ship.

-Side 2-Skin. - That is, this ductile cast iron material is well suited to the usage conditions and requirements of the bearing section 2.

Here, the reasons for limiting the components of the ductile cast iron material forming the trunk core lb and the bearing 2 will be described.

The amount of graphite and carbide of C is determined by the balance with the amount of Sj, and if it is less than 3.0%, graphitization will be insufficient, and if it is more than 3.8%, it will be excessively graphitized, resulting in a brittle material.

If Si is less than 1.5%, graphitization will be insufficient;
This is because if it exceeds Z%, excessive graphitization will occur, which is undesirable. In addition, since the shell outer shell material is generally made of a material with low Si content, if the inner surface is remelted and mixed into the core, the Si content will be lower than that of the moat component. It is necessary to consider that. Mn affects the matrix and carbide state, and if the content is too large, it will harden and become insufficient in strength, so the upper limit is set at 1.0% or less.

Although it is preferable to keep it to 0.4% or less, it may be contained in an amount of 0.4% or more based on the scales for adjusting the melted components. Ni mainly plays a role in hardening the matrix, but in the case of the main material, Ni is also mixed in from the high-alloy grain material that forms the outer shell of the body.
．． 0% or less is necessary and sufficient. Cr is a carbide-forming element, and if it exceeds 1.0%, it becomes hard and lacks sardine properties;
% or less, the hardness of the bearing portion decreases too much.

Although Mo does not originally need to be included, it is included by being mixed in from the outer shell of the body.

This is because if it exceeds 0.2%, the material becomes hard and the ballability becomes insufficient.

Mg is required in an amount of 0.03% or more for graphite spheroidization.

On the other hand, the steel material forming the neck end portion 3 is one that has at least a strong rut resistance that exceeds that of the high-grade cast iron used in the subordinate structure, that is, as mentioned above, the hardness is relatively low at Hs30 to 4.
5, but especially regarding tensile strength and elongation, it is 55k.
It is required that the content satisfies the content of 1.5% or more and preferably 65k9/iso or more. As a specific example of something that meets this purpose, for example, in S4,
Examples include using various carbon steel materials such as S4 or SF5. Moreover, if economic efficiency is not considered, SCM
Alloy steel materials such as steel may also be used. The composite roll of the present invention partially made of different materials as described above will be further explained with reference to FIG.

First, the material and hardness of the shell outer shell portion la that comes into contact with the rolled material is selected as appropriate in order to provide rolling performance depending on its intended use. In addition, regarding the trunk core part lb and the bearing part 2, the twilling properties with the outer shell part la, the required strength as a bearing part,
It is made of the above-mentioned ductile cast iron due to its hardness. On the other hand, for the neck end portion 3 where particularly strong rolling properties are required, one or both of the working side W and the driving side D of the roll is formed of the above-mentioned appropriate steel material.

In the embodiment shown in FIG. 4, which corresponds to the roll having the shape shown in FIG. The neck end 3 on the side W is made of steel. In this case, it is of course possible to form the neck end (not shown) on the drive side D from steel. Also, the bearing part 2
(relatively large in diameter) and the neck end 3 made of steel material, the neck end 3 must be wrapped around the bearing 2 at the boundary between the two, where the outer diameter suddenly becomes thinner. .

It is important that the bearing part 2 and the steel material that is surrounded by the insert/rust are completely welded together, but even if the welding is partially incomplete, it is still possible to withstand the bending stress that occurs at the boundary. In order to withstand the stress generated in the axial direction, the steel material to be wrapped around the key must be wrapped in the bearing part 2 with an appropriate length dimension 1, as shown in the figure, and at the same time, it is necessary to fit the key into the bearing part 2, as shown in the figure. It is necessary that the size of the AA is not too large compared to the diameter d of the bearing portion 2. That is, if d is larger than d, the welding will be insufficient and the strength of the bearing portion 2 will be insufficient due to the decrease in the wall thickness. On the other hand, in order to increase the tensile strength in the ball direction at the welded joint between the two, it is effective to provide a step S on the outer surface of the steel material as shown in the figure, but this is not always necessary if the welding is complete. Next, a method for manufacturing a composite roll according to the present invention will be explained.

This objective composite roll is preferably manufactured as follows by improving the conventional manufacturing technology of far zero force casting. In other words, as with the sub-chassis, the outer shell part l is first cast using a remote zero force casting machine.
After casting a, a centrifugal casting mold (mold) 4 containing this body outer shell part la, a lower mold 5 and an upper mold 6 prepared separately, and necessary injection weir needles 7, etc. are placed vertically. A mold for Seireki casting is constructed by assembling and connecting the mold, and a composite roll is cast by pouring the Shinmura molten metal into the mold.
As shown in the figure, the steel material 3 is charged in advance at a position corresponding to the neck end in the lower die 5 with the steel material 3 protruding upward by an appropriate dimension. Thus, by injecting the core material molten metal into this mold, the steel material 3 forms the core 3 forming the body core part lb and the bearing part 2.
Welded and wrapped in molten metal, arm outer shell part la, torso core part lb
It is possible to cast the desired composite roll in which the parts of different materials of the bearing part 2 and neck end part 3 are welded and integrated. In the embodiment shown in FIG. 5, sand mold parts 8 are provided on the inner surfaces of both ends of the far zero force casting mold 4, and the bearing part 2 is cast in these parts. Further, in this case, the casting steel material may be inserted into the insert for casting the steel material 3 on the upper mold 6 side from the upper part at an appropriate timing after pouring the core molten metal. In this way, in the present invention, the trunk core part lb, the bearing part 2, and the neck end part 3 are separated and integrated, so that the deep shrinkage cavity that occurs at the neck end part 3 when these are integrally cast is avoided. Defects can be reliably prevented, and since the bearing part 2 is thicker and has a larger heat capacity than the neck end part 3, if the neck end part 3 is integrated with the end face of the bearing part 2, portability becomes extremely good. In order to improve the weldability between the steel material forming the neck end portion 3 and the bearing portion 2, the following points should be kept in mind during manufacturing. First of all, it is important to sufficiently remove rust from the surface of the protruding part of the coin purse steel material 3 and keep it clean, and to keep it hot in order to promote settling. Surface treatments such as mountain surface treatment, shelf sand flux coating, or plating are also effective in improving weldability. On the other hand, regarding the sand mold part 8 for casting the bearing part 2,
In order to improve weldability, it is best to make the part thicker to increase the heat capacity of that part, or to use a sand mold with a high heat retention effect. 0 Regarding the centrifugal force casting method of the trunk outer shell portion la, in addition to the usual horizontal type, any of the oblique type and vertical type can be applied.

The as-cast roll finally cast by the above manufacturing method is
Normally, heat treatment is applied to each material in order to improve the properties of the body, but in the case of the present invention, only the neck end is required to make the properties of the steel material excellent in its original toughness. It is desirable to carry out partial heat treatment depending on the situation.

The present invention will be described with reference to specific embodiments.

0 (Example) Body diameter ○B6000, body length IB17001, neck diameter DN
2150, neck length IN18001, i.e. IN/IB=
Rolls of 1.00 1N/DN=8.37 in the shape shown in FIG. 4 were integrally welded and cast by centrifugal force casting using materials having the following chemical components.

Chemical composition (wt association) *Steel material S45C As can be seen from the test results in the table above, each part of the neck has the required properties, and in particular, the neck end has sufficient strong axial properties.

However, the above test results are based on measurements after optimal heat treatment has been applied to the outer shell. Further, as a result of observing the boundary between the bearing portion and the neck end portion, it was found that the two were well welded and integrated. As described above, the present invention forms one or both of the torso outer shell, the chest core, the bearing, and the neck end from the aforementioned different specific materials, and welds and integrates the three into a roll. Because of its structure, it satisfies the required properties in all parts, even for new types of rolls with long and narrow necks and large stress generated at the neck ends, which were not compatible with conventional composite rolls. Compound that can be forced.

It can provide a wide range of elasticity, and is fully compatible with intended uses that require strong sardine properties, particularly elongation, at the neck end. In addition, the body core, bearing, and neck machine are separated and integrated with lacquer, so even if the neck is long and slender, deep shrinkage cavities will not occur at the end of the neck. Since the roll is thicker than the end portion and has a larger heat capacity, the rolling roll according to the present invention in which the neck end portion is welded and integrated with the bearing portion end face is extremely well welded and integrated with the bearing portion. It should be noted that the present invention can be similarly applied to the neck end 3' of a single roll 9 whose body and bearing are integrally formed of the same material, as shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an example of the shape of a conventional rolling roll, and FIG. 2 is a side view showing an example of the shape of a rolling roll to which the present invention is applied.

FIG. 3 is a partially enlarged side view of a rolling roll to which the present invention is applied, and FIG. 4 is a half-sectional side view showing an example of the structure of the rolling roll according to the present invention. FIG. 5 is a sectional view of a mold schematically showing the method for manufacturing a composite roll according to the present invention. FIG. 6 is a sectional view of a single roll showing an application example of the present invention. 1...Chest, la...Arm outer shell, lb...Chest core, 2...Bearing part, 3...Neck end (steel material), 4...Centrifugal Power casting mold, 5, 6...
・Lower mold, upper mold.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. The body is formed of an outer shell made of adamite material or alloyed cast iron, and a core part that is integrally cast concentrically with the outer shell, and In a rolling roll in which a neck portion is formed by a bearing portion integrally cast with the body core portion on both sides of the body core portion and a neck end portion integrally welded on both sides of the bearing portion, the neck length l_N and body length l_B
The ratio l_N/l_B between l_N and the neck end diameter D_N is 0.8 to 1.2, or the ratio l_N/D_N between l_N and the neck end diameter D_N is 3.8 to 1.
3.0, and one or both of the neck ends have a smaller diameter than the bearing, and the body core and bearing have a hardness of 40.
~50, tensile strength 40~55kg/mm^2, elongation 0.
It is made of spheroidal graphite cast iron material with a hardness of 5 to 1.5%, and one or both of the neck ends has a hardness of H_s30 to 45 and a tensile strength of 5.
A rolling roll having a strong neck part, characterized in that it is made of a steel material having a tensile strength of 5 kg/mm^2 or more and an elongation of 1.5% or more. 2 The spheroidal graphite cast iron forming the core part and bearing part is C
:3.0~3.8% Cr:0.1~1.0% Si:
1.5-2.5% Mo: 0.2% or less Mn: 0.4
~1.0% Mg: 0.03% or more, Ni: 2.0% or less, respectively, by weight, and the balance is Fe and impurities. The rolling roll having a strong neck portion according to claim 1. 3 After centrifugally casting the shell outer shell, a mold containing the shell outer shell is connected to a separately prepared lower mold and an upper mold to form a stationary casting mold, and In a method of casting a composite roll by pouring a core material molten metal into a core material, a steel material is charged in advance at a position corresponding to the neck end in the lower mold, and the steel material is poured into a core material molten metal material that forms a body core part and a bearing part. A method for manufacturing rolling rolls with strong neck parts, characterized by welding and casting.