JPS6018251B2 - Rolling roll with strong neck part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a roll having a new structure that is most suitable for a rolling roll having an elongated neck shape, a special shape requiring particularly strong plowing properties at the neck end, and usage characteristics. Regarding.

Generally, rolling rolls are composed of a body and a neck.
The body portion is formed of a Tsukioka outer shell portion and a body core portion which is integrally cast concentrically with the same outer shell portion, and the neck portion is formed with eight concentric portions on both sides of the eight concentric portions. It is formed of a bearing part that is integrally cast and neck parts that are integrally cast on both sides of the bearing part.

In recent years, in hot strip mills for rolling steel plates, new types of rolling rolls with neck shapes and operating conditions different from conventional ones have been researched and developed in order to control the shape of steel plates. In other words, these methods are used to shift (move) work rolls in the axial direction, to forcibly suspend a work call, or to cross two work rolls with respect to the axis of a backup roll. It is. However, work rolls used in these rolling methods tend to have smaller diameters.

Furthermore, due to the type of rolling mill, the length of the neck must be longer than that of the follower roll, and the diameter of the neck must also be smaller. In addition, in this type of roll, greater stress is generated in the neck portion than in the past, and particularly strength 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. .

ZN and NノZB DN
and N/DN DB conventional roll shape 10
00~1400 0.52~0.75 340~5
00 2.0~3.6 650~840 Special Ro
Roll shape 1500~2000 0.80~1.
20 130~330 3.8~13.0 50
0~760mm N: Neck length B: Torso
DN: Neck end diameter (length) DB: Body diameter. ) As mentioned above, in the rolls used for this new rolling method,
Generally, the ratio of neck length to torso length IN/18 is 0.8 to 1.2,
Or the ratio IN/DN of neck length and neck diameter is 3.8 to 13.
．． It is characterized by having an elongated neck shape in which one or both of the neck weave portions are made smaller than the bearing portion.

By the way, the required characteristics of the neck portion of such a specially shaped rolling roll differ depending on its axial direction, and the bearing portion 2 near the body portion 1 is required to have wear resistance and toughness against friction with the bearing. On the other hand, the neck end 3 remote from the chest 1 is elongated in shape and requires particularly strong rut resistance because it needs to withstand large stresses.

In addition, in this specially shaped roll, as shown in FIGS. 2 and 3, there is a part of the neck weave 3 that is longer in diameter than the neck end fleas DN, and depending on the rolling method, for example, on the work side W. Particularly strong toughness is required in this part because a large thrust stress is generated and a large rubbing stress is generated on the driving side D.

In this way, the present invention has a neck length to torso length ratio IN/IB of 0.
．． 8 to 1.2, or the ratio of neck length to neck diameter IN/DN
Intended for special rolling rolls that have an elongated neck shape with a diameter of 3.8 to 13.0 and generate large stress at the neck end, the body and bearing parts are It is integrally formed of adamite material, and one or both of the neck ends are formed of particularly strong graphite mirror steel, which is a different material from the above-mentioned 8 parts and the bearing part, and the two are welded together to form a new roll structure. This is what we offer.

Single-cast Adamite rolls having the chemical compositions listed below are generally used for work roll middle and front stands conventionally used in hot strip mill finishing stands. Chemical component (Wt*) C Si Mn P S
NiCrMoVN
bl. 5) 2.0 0.3~1.0 0.5~1.
5 0.05 or less 0.05 or less 0.2-2.0
0.5) 3.0 0.2-1.0 2.0 or less
2.0 or less This single Adamite roll is intended to provide poor skin roughness resistance, abrasion resistance, and crack resistance to the body, and has a hardness of Hs 45 to 65.

Furthermore, in conventional rolling mills, the neck length IN is not very long and the neck diameter DN is quite large, so even if the neck part is integrally made of the same material as mentioned above, which is aimed at the use characteristics of the body part, there is no problem in terms of strength. It didn't happen. Incidentally, the neck strength of this type of single roll is as follows. Tensile strength of the neck end of a single Adamite roll: 40-5
5k9/fence elongation 0.3 to 1.5% However, as a result of intensive research by the present inventors, when a conventional roll is applied as it is to a roll for the shape intended by the present invention, the neck end It was found that due to insufficient strength in part 3, it could not withstand use at all.

In other words, the conventional technical means of forming the roll neck portion from the same material cannot be an effective means of manufacturing the intended roll. In addition, since the rolling roll according to the present invention has a long and narrow neck, if the entire body is integrally cast like a single Adamite roll, a deep shrinkage cavity-like defect will occur at the neck end along the roll axis. It was difficult to manufacture. Therefore, the present invention, as shown in FIG.
The same part 1 and the bearing part 2 are integrally formed on the same machine with the above-mentioned adamite material as in the case of a conventional single roll, while one or both of the neck end part 3, which requires further toughness,
This is separately formed from strong graphite steel, and the eight parts 1 and bearing part 2 of this different material and the neck end part 3 are welded and integrated to form a roll.

The strong sardine material forming the neck end 3 here is superior in strength, elongation, etc., at least to the conventional single adamite roll described above.

That is, it has a hardness of about 30 to 48 Hs, and a tensile strength of at least 55k9/hs and 1.5
% or more. An example of a strong material suitable for this purpose is:
So-called graphite mirror steel materials with the following chemical components are listed.

Chemical component (Wt-rich) C Si M
n P S Ni Cr
Mo BoZI. 0~1.8 1.2~
1.8 0.3 to 1.0 0.05 or less 0.05 or less 1.0 or less 0.2 to 0.8 0.5 or less Fe and impurities Here, component limitation of the above material forming the neck end 3 I will explain the reason.

This is because if C is less than 1.0%, castability is poor, and although toughness is good, hardness becomes too low and graphitization becomes insufficient.

On the other hand, if it exceeds 1.8%, the rutting property will be insufficient. In relation to the amount of C, 1.2% or more of Si is necessary to promote graphitization, but if it is 1.8% or more, there will be too much graphite or too much carbide, resulting in a brittle material. It is desirable that Mn be contained in an amount of 0.3% or more for deoxidizing the molten metal, and if it is 1.0% or more, toughness will be insufficient.

It is desirable that P and S be as small as impurities, 0.05%.
The reason for this is that the plowability is inhibited.

This is because if Ni is 1.0% or more, it hardens the material base and reduces toughness. Cr adjusts the amount of graphite and carbide by balancing with the amount of C and Si. This is because if it is less than 0.2%, there will be too much graphite and the hardness will be low, while if it is more than 0.8%, there will be a lot of carbides and it will become brittle.

This is because Mo content of 0.5% or more causes hardness and a decrease in toughness.

55kg is required for graphite steel material with specific components as mentioned above.
It is suitable as a strong rutting material for the intended purpose, as it can satisfy both the tensile strength of 1.5% or more and the elongation of 1.5% or more, and has good adhesion to the body part 1 and bearing part 2. It is something.

Regarding the hardness of the tough material forming the neck end 3, it is better not to be too high in order to ensure toughness, but on the other hand, there is also the problem of rotational wear, so it is better to have a hardness of S30 to 4. Appropriate. The hardness of the above-mentioned graphite steel generally falls within this hardness range. The so-called high C adamite material forming the chest 1 and the bearing part 2 has a relatively large amount of alloy, so it can be heat-treated to have a hardness of Hs 45 to 60.
Needless to say, the desired properties such as wear resistance can be easily achieved. Next, a method for manufacturing the present invention (three rolls) will be briefly explained.

In casting the roll of the present invention, the body part 1 and the bearing part 2 are cast in the same manner as in the case of manufacturing a conventional single Adamite roll.
It is convenient to simultaneously cast the neck end 3 in one piece and then use a separate molten graphite mirror steel to cover the neck end 3. Conversely, after placing the neck end 3 on the lower mold side and pre-casting it,
The body part 1 and the bearing part 2 may be cast together so that they are joined together. In any case, if both the left and right neck ends 3, 3 are made of graphite cast steel, which are different materials, they are attached to the body part 1 and the bearing part 2, respectively, and integrated, and only one neck end part 3 is made of graphite cast steel. In the case of forming steel, only one of them is attached to the chest 1 and the bearing part 2, and the other is attached to the body part 1 and the bearing part 2.
It is sufficient to integrally cast the same material. As shown in this figure, in the present invention, the bearing part 1, the bearing part 2, and the neck end part 3 are separately cast and integrated, so that the deep shrinkage that occurs at the neck end part 3 when these are integrally cast is avoided. Nested 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 integrally cast with the end face of the bearing part 2, weldability will be extremely good. After the neck part is integrally cast with different materials in the axial direction, the entire roll of the same machine is conventionally subjected to a diffusion heat treatment, and then the body part 1 is subjected to a quenching heat treatment or a quenching heat treatment, and finally a strain relief heat treatment is performed.

The neck end portion 3, which is made of a strong material, is separately heat treated to improve its toughness while taking care not to introduce any hardening effects. The present invention will be described with reference to specific embodiments.

(Example) Body flea DB6500, body length IB17001, neck diameter DN219, neck length IN18001, that is, IN
/IB = 1.06, IN / DN = 8.37, a roll having the shape shown in Fig. 4 was made with graphite steel made of a different material at only one neck end, and the following chemical composition was prepared. It was cast using the following materials. Chemical composition (Wt%) C Si Mn P
S Ni Cr Mo same part and bearing part and 1.82 o. 54 o. 97
o. o31 0.012 0.67 1.24
0.58 One neck end Other neck end 1
．． 51 1.56 0.47 0.030 0
．． 021 0.43 0.24 0.06After casting, continue with diffusion heat treatment-8Akatsuki semi-heat treatment is applied only to the same part,
After that, heat treatment for strain relief was performed.

As a result, the roll body is made of a material with a hardness of Hs 52 to 54 and excellent roughening resistance, while one neck end has a hardness of Hs 38 to 41 and a tensile strength of 60.7 to 65.7k.
9/Ground, with an elongation of 2.4 to 3.2% and excellent strong sea bream properties. Figure 5 shows the microscopic tissue of the chest.
Figure 6 shows the microscopic structure of the highly rutted neck end. It should be noted that the coin pockets of both were completely metallurgically connected and were sound with no defects. As described above, the present invention forms a roll by integrally forming the 8 okabe and the bearing part from adamite material, forming one or both of the neck oribe from a different strong graphite steel, and welding and integrating the two. Therefore, even for new types of rolls with elongated necks and large stress generated at the neck ends, which could not be handled by single rolls with attached shafts, the body and bearings are While satisfying each required property, the neck end can be given sufficient strength to meet the usage conditions. In addition, since the Tsukioka part, the bearing part, and the neck end part are separated and integrally cast, even if the neck part is long and thin, deep shrinkage cavities will not occur at the neck end part, and the bearing part will not be formed at the neck end part. Since the rolling roll is thicker and has a large heat capacity, the rolling roll according to the present invention, in which the neck end is integrally cast on the end face of the bearing part, has the neck end very well settled and integrated with the bearing part.

[Brief explanation of the drawing]

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. 5 and 6 are micrographs showing the metallographic structure of an example of a composite roll according to the present invention, in which FIG. 5 shows the body part and FIG. 6 shows the neck end part. 1...Body part, 2...Bearing part, 3...
...Neck Oribe. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. A trunk section is formed of a trunk core part that is integrally cast concentrically with the trunk outer shell part, and bearing parts are integrally cast with the trunk core parts on both sides of the trunk core part. and neck end portions integrally cast on both sides of the bearing portion, the ratio l_N/l_B of neck length l_N to body length l_B 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 13.0.
In addition, one or both of the neck ends have a smaller diameter than the bearing part, the body part and the bearing part are integrally cast from adamite material, and one or both of the neck ends have a hardness of Hs30.
~48, tensile strength 55kg/mm^2 or more, elongation 1.5
% or more of tough graphite cast steel. 2. The tough graphite cast steel that forms the neck end has a C:1.
0-1.8% S: 0.05% or less Si: 1.2-1.8
%Ni: 1.0% or less Mn: 0.3-1.0% Cr: 0
．． 2-0.8% P: 0.05% or less Mo: 0.5% or less by weight, with the remainder being Fe and impurities.