JPS5948686B2 - Composite roll for sheet pile rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite roll for rolling sheet piles, which has the necessary characteristics in each part of its groove in a single roll, has a long service life, and is economical.

Among the rolls for rolling shaped steel, those especially for rolling sheet piles (steel sheet piles) have a hole shape as shown in FIG.

Two rolling methods are used: a double rolling mill that rolls with an upper roll and a lower roll, each roll having a large number of grooves, and a double rolling mill, which rolls with upper and lower rolls each having one groove. There is a method to do this.

In the latter case, as shown in FIG. 1, a roll may be used in which a sleeve 2 having a hole formed in a shaft 1 is assembled by shrink fitting or the like.

The hole shape for this sheet pile generally has a deep recess 3 and a protrusion 4 due to the shape of the product, and the protrusion 4 surrounded by the product 5 has local wear 6 and an axial direction as shown in FIG. Fine cracks 7 are likely to occur, while local wear 8 is likely to occur in the concave portions 3.

By the way, conventional sleeve materials of this type include C1,0~1
．． Graphite steel roll material containing 8% or CO・6~1
．． Special cast steel materials containing 2% have been mainly used.

However, as described above, the convex portions and concave portions of the hole mold have different required characteristics, and if the entire hole mold is made of the single material described above, it is not possible to satisfy the requirements of each portion of the hole mold.

Therefore, as a solution to the problem of rolls for rolling shaped steel, as shown in FIG. 3, split sleeves 2a, 2b, 2
b, 2d, 2e-...
62) or as shown in Fig. 4, the roll body 2A
Among the many hole shapes, the hole portion that requires durability is constructed with a sleeve material 2B that has excellent crack resistance (Utility Model Publication No. 51-22133, and other Japanese Utility Model Applications No. 52-74336). (Japanese Patent Publication No. 55-26921) have been proposed.

However, such a structure cannot be an effective solution to the problem that different characteristics are required for the convex portion and the four portions of one hole.

The present invention provides a composite roll for sheet pile rolling having a new structure that can solve the above problems.

By the way, as a rolling machine of this type, a structure as shown in FIG. 5 has been conventionally used.

That is, the sleeve 2 has two layers 9' and 10', an inner and outer layer, and the outer layer 9' covers the entire hole shape from the new diameter (indicated by the solid outline line in the figure) to the waste diameter (indicated by the broken line in the figure). The inner layer 10', which is a portion not subjected to direct rolling, is formed to the desired thickness to withstand stress during assembly to the shaft 1.
The outer layer 9' is made of a different material.

However, even in this case, the hole surface is still formed of the same outer layer material.

On the other hand, the present invention provides two layers 9, 10 of the sleeve 2, which are made of different materials and metallurgically combined, as shown in the sixth section.
The outer layer 9 has a thickness that forms only the convex portions 4 of the hole, while the inner layer 10 has the recess 3 of the hole and the inner thick portion 1 not subjected to rolling, i.e., the hole. The recess 3 of the mold and the thick part of the inner layer 10' of the conventional composite roll are made of the same material.

In the composite roll having such a configuration, the outer layer 9 forming the groove-shaped convex portions 4 is formed of a material having the necessary wear resistance and crack resistance, while the inner layer 10 forms the groove-shaped concave portions. By forming the sleeve 2 with a material that has the wear resistance required for 3 and the toughness to withstand the shrink fit stress generated on the inner surface of the sleeve 2, it is possible to satisfy the characteristics required for each part of the hole. , especially on the inner surface of sleeve 2 (
1 can satisfy the required toughness and can improve the performance of this type of composite roll as a whole.

The outer layer 9 and the inner layer 10 that meet the purpose of the present invention as described above
Regarding the specific materials, combination examples such as special cast steel and graphite steel, special cast steel and ductile cast iron, graphite steel and special cast steel, and graphite steel and ductile cast iron can be proposed.

Specific examples of preferable materials for the outer layer 9 and the inner layer 10 will be listed later.

Next, the required thickness of the outer layer in the composite roll according to the present invention will be explained.

As shown in Fig. 7, the new diameter (the diameter of the hole-shaped convex part is Dl, the diameter of the hole-shaped concave part is D4, the diameter of the hole-shaped convex part after discarding is D2, and the diameter of the hole-shaped concave part is D1). Let the diameter be D5.

The outer layer needs to have a sufficient thickness even after discarding in order to prevent local abrasion and heat cracking of the hole-shaped convex parts, so the diameter D3 of the boundary between the outer layer and the inner layer is at least D2>
Must be D3>D4.

However, in reality, not only the leading edge of the hole-shaped convex portion requires wear resistance and crack resistance, but also the portion slightly lower than that requires a problem.

Therefore, it is desirable that the actual boundary diameter D3 satisfies (D2-50)>D3 with a margin of about 25 mm on each side.

On the other hand, for the hole-shaped recess, a margin of about 10 mm is required, and it is desirable that D3>(D4+20).

Therefore, the thickness of the outer layer is the boundary diameter D3 of the inner and outer layers, (D2
-50)>D,>(D4+20) It is preferable to adjust the value as follows.

Note that the inner diameter D6 of the sleeve must naturally be smaller than the diameter D5 of the recess at the time of disposal, but in order to withstand the stress on the inner surface of the sleeve due to assembly, it must be as small as possible in relation to the diameter of the shaft. .

As an example of the sleeve outer layer material and inner layer material used in the composite roll of the present invention, a combination of an outer layer of special cast steel and an inner layer of graphite steel having the following chemical composition and hardness is suitable.

In addition, the above inner layer is made of SiO, 1 to 1.0% with an inoculant.
It is preferable to inoculate in portions.

Regarding the above special cast steel material for the outer layer and graphite steel material for the inner layer,
The chemical composition, hardness, and other characteristics of each will be explained in detail.

[Outer layer: special cast steel]

i Chemical composition (wt%, remainder Fe and normal impurities) C: 0.6-1.5% If C is less than 0.6%, the material will be soft and wear resistance will be insufficient; If it exceeds this amount, carbides will increase and crack resistance will decrease.

Si: L, Q% or less Si requires an appropriate content for deoxidation, but 1.
If it exceeds 0%, the material becomes brittle.

Mn: 0.2-1.0% Mn combines with S and is effective in removing the adverse effects of S, but if it is less than 0.2%, this effect is insufficient;
If it exceeds 0%, the material will deteriorate.

P: 0.05% or less P is set at 0.05% or less because it makes the material brittle.

S: 0.05% or less S also makes the material brittle, so it should be kept at 0.05% or less.

Ni: Q, 1-2.0% Ni hardens the base and is effective in improving toughness and wear resistance, but less than 0.1% is insufficiently effective, while 2.0%
There is no need to exceed.

Furthermore, if the Ni content is too large, the seizability will decrease and seize-like wear will be accelerated.

Cr: 0.5-2.0% Cr is effective in stabilizing cementite and is effective in improving wear resistance at high temperatures.

If it is less than 0.5%, this effect is insufficient, and if it exceeds 2.0%, it is not necessary.

Mo: 0.1-1.0% Mo, like Ni, is an element necessary for improving toughness, but if it is less than 0.1%, its effect is insufficient; on the other hand, 1.
If it exceeds 0%, it becomes hard and crack resistance deteriorates.

It should be noted that this special cast steel material for the outer layer may be added with other alloying elements such as V and Nb, or may contain a small amount of Ti, Al, Zr, etc. as a molten metal processing agent.

ii Hardness: Hs38-50 The outer layer needs to have a hardness of Hs38 or higher in order to improve the abrasion resistance of the hole-shaped convex portion, while if it exceeds Hs50, crack resistance cannot be maintained.

[Inner layer: graphite steel]

i Chemical composition (wt%, balance Fe and normal impurities) C:1. O~2.0% C is dissolved in the matrix and appears as graphite (or a portion becomes eutectic cementite).

However, if C is less than 1.0%, the melting and casting temperatures will be high, resulting in an increase in cost, while if it exceeds 2.0%, the graphite will tend to lose its spherical shape, resulting in a decrease in toughness.

Si: 0.6-3.0% Si has a close relationship with the crystallization of graphite, and if it is less than 0.6%, it becomes almost difficult to crystallize graphite.

However, if the content exceeds 3.0%, Si dissolved in the matrix tends to significantly deteriorate the toughness of the material.

Mn: 0.2-1.0% Mn combines with S and is effective in removing the adverse effects of S.

If MnO is less than 2%, there is no effect, while if it exceeds 1.0%, the toughness of the material deteriorates.

P: 0.1% or less P increases the fluidity of the molten metal, but it makes the material brittle.
Keep it below 1%.

S: 0.1% or less S, like P, weakens the material, so it is suppressed to 0.1% or less.

Ni: 0.1 to 2.0% Ni delays the transformation of the material and is effective in improving toughness.

This effect is small when NiQ is less than 1%, and there is no need to exceed 2.0%.

Cr: 0.1-3.0% Cr is effective for toughening and stabilizing cementite, and is contained in an amount of 0.1% or more to ensure toughness.

However, if the Cr content is too high, it will become chilled and brittle.
Moreover, since the Cr content in the inner layer increases as it mixes with the outer layer, it is desirable to keep it low.

The upper limit for graphite crystallization is set at 3.0% or less.

Mo: 0.1 to 1.0% Like Ni, Mo is an important element in ensuring toughness.

This effect of Mo content cannot be achieved if it is less than 0.1%.

However, if it exceeds 1.0%, it becomes hard and rather brittle.

ii. Inoculation In order to promote graphitization, inoculation is generally known to give good results.

For this material as well, by applying inoculation technology, an inoculant such as CaSi, FeSi, etc. is applied to the material immediately before casting, and the Si content is reduced to 0.
．． Addition of 1 to 1% is more effective in improving toughness.

There is no effect if the inoculation amount is less than 0.1%, and there is no need to exceed 1.0%.

The effect of this inoculation is particularly effective when the Cr content increases.

Note that the Si content after inoculation is adjusted to stay within the above range of 0.6 to 3.0%.

iii Hardness: H840-55 The inner layer must have Hs40 or higher to ensure wear resistance of the hole-shaped recesses.

However, if the hardness is too high, there will be too much difference in the structure and wear resistance at the boundary with the outer layer, so the upper limit is set to Hs
55.

Next, specific examples of the composite roll according to the present invention will be described.

<Example> New roll dimensions Diameter of the convex hole 1230φ Diameter of the concave hole 1018φ Dimensions at roll disposal Diameter of the convex hole 1114φ Diameter of the concave hole 902φ For a roll for sheet pile rolling, the outer layer thickness is 110
The outer and inner layers of the sleeve were formed of the following materials under the following conditions: mm (boundary diameter between outer layer and inner layer: 1010 φ), shrink-fit portion diameter: 660 mm, and inner layer depth: 175 mm.

However, the inner layer was inoculated with 0.5% Ca-5i as Si.

After the outer and inner layers of the above components were centrifugally cast, they were subjected to diffusion heat treatment, standardization, and tempering heat treatment.

As a result, the outer layer of the sleeve is made of a material with excellent wear resistance and crack resistance required for the groove-shaped convex part, while the inner layer has the wear resistance required for the groove-shaped concave part and the toughness required for the inner surface of the sleeve. A graphite steel material with excellent properties was obtained.

As described above, the composite roll for sheet pile rolling of the present invention is centered around a sleeve consisting of two layers: an outer layer forming a groove-shaped convex portion and an inner layer forming a groove-shaped recess and a thick portion not subjected to rolling. Since it is constructed by assembling, it is possible to simultaneously satisfy the properties required for each part of the hole mold, and its useful life can be extended.

Furthermore, in the sleeve according to the present invention, since the hole-shaped recess and the thick inner wall portion of the sleeve that is not subjected to rolling are formed of the same material, two types of materials can be used to manufacture one sleeve. Well, it's also economical in this respect.

The composite roll of the present invention can be applied not only to the original sheet pile rolling but also to rail and channel rolling.

Furthermore, in the above explanation, an example of a roll was described in which a sleeve is assembled onto a shaft by shrink fitting, etc., but the technical idea of the present invention is a roll in which the inner layer of the sleeve and a shaft portion are integrated, and a roll with many holes in one roll. Applicable to rolls with molds.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view showing an example of the structure of a sheet pile rolling roll, and FIG. 2 is an upper half side view showing how the roll is damaged during use. FIGS. 3 and 4 are sectional views of essential parts showing an example of an improved structure of a sheet pile rolling roll. FIG. 5 is an upper half sectional side view showing a conventional composite roll for sheet pile rolling. FIG. 6 is an upper half sectional side view showing the composite roll for sheet pile rolling of the present invention. FIG. 7 is a diagram for explaining the thickness relationship between the outer layer and the inner layer of the sleeve. 1...shaft, 2...sleeve, total...
... Hole-shaped concave portion, 4... Hole-shaped convex portion, 9...
・Outer layer, 10... Inner layer.

Claims (1)

[Scope of Claims] 1. A sleeve formed by metallurgically bonding an outer layer forming a convex portion of a hole and an inner layer forming a recess of a hole and a thick portion not subjected to rolling, is assembled on a shaft. A composite roll for sheet pile rolling, which is characterized by: 2 When the new diameter of the hole-shaped concave part of the sleeve is D4, the boundary diameter of the inner and outer layers is D3, and the discarded diameter of the hole-shaped convex part of the sleeve is D2,
Outer layer thickness is (D2 50) >D3> (D4+20)
A composite roll according to claim 1, which satisfies the following. 3 Outer layer is C006~1.5, Si1.0 or less, Mn
002~1.0, Po, 05 or less, So, 05 or less,
NiQ, 1-2.0, Cr005-2.0, MOo, 1
~1.0% by weight, the remainder substantially consisting of Fe,
It is made of special cast steel with hardness Hs38~50, while the inner layer is C1,0~2.0.5iO16~3.0,
MnQ, 2-1.0, PO01 or less, So, 1 or less, Nip, 1-2.0, Cr005-1.0, MOo
, 1 to 1.0% by weight, the remainder substantially consisting of Fe, and having a hardness of Hs 40 to 55.