JPS5948687B2 - Multilayer roll for sheet pile rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer roll for sheet pile rolling, in which a single roll can provide the necessary properties for each part of the groove, thereby extending the rolling life.

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

The rolling method is one row. There are two types of rolling mills: one is a double rolling mill in which rolling is performed using an upper roll and a lower roll each having a large number of holes, and the other is a method in which rolling is performed using upper and lower rolls in which one roll is provided with one hole.

In the latter case, as shown in FIG. 1, a roll may be used in which a sleeve 2 with 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 CO06~1
．． 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, the split sleeves 2a, 2b, 2
C, 2d, 2e... (Jikko Sho 53-462
62) or as shown in Fig. 4, the roll body 2A
Among the many hole shapes, the hole portion that requires crack resistance is constructed with a separate sleeve material 2B that has excellent crack resistance (Japanese Utility Model Publication No. 51-22133 and other Japanese Utility Model Application Publications No. 52-74336, Japanese Patent Publication No. 55-26921) has been proposed.

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

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

That is, the sheet pile rolling roll of the present invention has the fifth
As shown in the figure, the sleeve 2 has a three-layer structure made of different materials and metallurgically bonded, and the first outer layer 9 has a thickness that forms only the hole-shaped convex portion 4. The second outer layer 10 has a thickness that forms the four parts (bottom parts) 3 of the hole shape, and the inner layer 11 is a three-layer structure that forms a thick part inside the sleeve that is not directly subjected to rolling. It is characterized by being assembled around a sleeve.

In the multilayer roll having such a configuration, the first outer layer 9 constituting the convex portions 4 of the groove is formed of a material having the necessary wear resistance and crack resistance, and the four portions 3 of the groove are formed of a material having the necessary wear resistance and crack resistance. The second outer layer 10 is made of a material with the required wear resistance, and the inner layer 11 is made of a tough material that can withstand the stress generated by shrink fitting or other assembly methods. It is possible to satisfy the required characteristics for each part of the mold, and at the same time, it is possible to satisfy the necessary toughness for the sleeve 2, especially its inner surface, and the performance of this type of sleeve roll as a whole can be reasonably improved.

Regarding the specific materials of the first outer layer 9, second outer layer 10, and inner layer that meet the purpose of the present invention, special cast steel, graphite steel, etc. are suitable for the first outer layer, and for the second outer layer, These include graphite steel, special steel, and adamite materials.

Although ductile cast iron is suitable for the inner layer, other strong materials such as cast steel and graphite steel may also be used.

Note that specific examples of preferred materials for the first outer layer, second outer layer, and inner layer will be listed later.

Next, the necessary thicknesses of the first outer layer and the second outer layer in the multilayer roll according to the present invention will be explained.

As shown in Fig. 6, the diameter of the convex part of the hole in the new diameter is D and the diameter of the concave part is D4. The diameter is D2, and the diameter of the hole-shaped recess is D5.

Then, the first outer layer forming the hole-shaped convex portion is locally worn,
In order to prevent the occurrence of heat cracks, it is necessary to have a sufficient wall thickness even after disposal.

Therefore, the boundary diameter D3 between the first outer layer and the second outer layer must be at least D2>Da>D4.

However, in reality, it is not only the leading edge of the hole-shaped convex portion that requires wear resistance and crack resistance, but parts that are slightly more resistant also pose a problem.

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

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

Therefore, if the thickness of the first outer layer is 1, the boundary diameter D3 between the first outer layer and the second outer layer is (D2-50) >Da> (D4-20)
It is preferable to adjust so that

Next, the boundary diameter D6 between the second outer layer and the inner layer should be smaller than the diameter D5 of the hole-shaped recess after discarding.

However, in this case as well, it is desirable to have a margin of about 10 m for each piece + T1.

Therefore, the thickness of the second outer layer is preferably adjusted so that the boundary diameter D6 between the second outer layer and the inner layer satisfies (Ds 20) >D6.

The inner layer is preferably thicker in order to withstand fastening stress such as shrink fitting.

Note that it is desirable that the diameter D7 of the assembled portion by shrink fitting or the like be as small as possible, although it depends on the relationship with the shaft diameter.

As an example of the sleeve material used in the multilayer sleeve roll of the present invention, a combination of the first outer layer - special cast steel, the second outer layer - graphite steel, and the inner layer - ductile cast iron having the following chemical composition and hardness is suitable. It is preferable to inoculate the second outer layer with an inoculant containing 1 to 1.0% of Sin.

The chemical composition, hardness, and other characteristics of the special cast steel material for the first outer layer, the graphite steel material for the second outer layer, and the ductile cast steel material for the inner layer will be described in detail.

[First outer layer: special cast steel] i Chemical composition (wt%, remainder Fe and normal impurities) C: 0.6 to 1.5% If C is less than 0.6%, the material will be soft and have insufficient wear resistance. However, if it exceeds 1.5%, the amount of carbides increases and crack resistance decreases.

Si: 1.0% or less Si requires an appropriate content for deoxidation, but 1.0%
If it exceeds %, 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 exceeds 0.2%, it deteriorates the material.

P: 0.05% or less P is set to 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: 0.1-2.0% Ni has the effect of hardening the base and 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% (Mg 0.02-0.1) 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.

In addition, this special cast steel material for the outer layer also contains alloying elements such as (1) and Nb, as well as Ti, AI, and Z as molten metal processing agents.
There is no hindrance to adding a small amount of r or the like.

ii Hardness: Hs38-50 The outer layer needs to have a hardness of Hs38 or higher in order to improve the wear resistance of the hole-shaped convex portions.On the other hand, if the hardness exceeds Hs5Q, crack resistance cannot be maintained.

[Second outer layer: graphite steel] i Chemical composition (wt%, remaining Fe and normal impurities) C: 1.0 to 2.0% C is dissolved in the matrix and also appears as graphite (or a part of it is co-existence). (becomes crystalline 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: Q, 5-3.0% 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 Mn is less than 0.2%, 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 is suppressed to 0.1% or less in order to make the material brittle like P.

Ni: Q, 1-2.0% Ni retards the transformation of the material and is effective in improving toughness.

This effect is small when Nip 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 in order to ensure toughness, 0.1% or more is contained.

However, if the Cr content is too high, it will become chilled and brittle.
Furthermore, since the Cr content in the inner layer increases when mixed with the second 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.

The effect of containing MO 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 or FeSi is applied to reduce the Si content to zero immediately before casting.
．． Addition of 1 to 1% is more effective in improving toughness.

If the inoculation amount is less than 0.1%, it will not be effective, and it is not necessary to exceed 1.0%.

This inoculation effect 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: Hs40-55 The second outer layer must have a hardness of Hs40 or more 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 first outer layer, so the upper limit is set to Hs55.

[Inner layer: ductile cast iron]

i Chemical composition (wt%, remainder Fe and normal impurities) C: 2.8 to 3.8% As described later, this material is made of spheroidal graphite cast iron material.

Here, if C is less than 8%, chilling of the material progresses and toughness decreases.

On the other hand, if it exceeds 3.8%, graphitization will be excessive and strength will be insufficient.

Si: 1.5-3.2% Si is contained mainly for the purpose of controlling graphitization, but 1.
If it is less than 5%, graphitization will be insufficient, while if it exceeds 3.2%, graphitization will be excessive and Si dissolved in the ferrite will weaken the material.

Mn: 0.3-1.0% Mn usually combines with S and is effective in removing the adverse effects of S, but if it is less than 0.3, it has no effect;
If it exceeds 0%, the material becomes hard and brittle.

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

S: 0.03% or less S must be kept low in order to make the graphite spheroidal, and should be kept at 0.03% or less.

Ni: 2.0% or less Ni acts effectively on graphitization and strengthening the base, but 2.0%
If it exceeds 2.0%, the effect will be saturated, so from the economic point of view it should be 2.0% or less.

Cr: 3. Q% or less Cr has a stabilizing effect on cementite, but if it exceeds 3.0%, the material becomes chilled and becomes brittle.

Mo: 0.6% or less Mo has a reinforcing effect on the matrix, but if it exceeds 0.6%, this effect will be saturated and there will be a noticeable tendency to harden the material, so it should be kept at 0.6% or less.

Mg: 0.02 to 0.1% Mg is added to make graphite spheroidal, but 0.02% to 0.1%
．． If it is less than 0.02%, it has no effect, while if it exceeds 0.1%, it is not preferable because it tends to cause chilling effect of Mg and casting defects such as dross.

ii Hardness: Hs38-50 Since the inner layer needs to have toughness, it should be in the range of Hs38-50.

That is, if Hs is higher than 50, the toughness is insufficient and the sleeve cannot withstand stress during assembly or rolling, resulting in breakage.

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

. 〈Example〉 New roll dimensions Diameter of convex hole 1230φ Diameter of concave hole 1018φ Roll scrap size Diameter of convex hole 1114φ Diameter of concave hole 902φ For sheet pile rolling roll, first outer layer thickness 1
05mm (boundary diameter between the first outer layer and the second outer layer 1020φ)
, second outer layer thickness 78 mm (boundary diameter between second outer layer and inner layer 8
The first outer layer, the second outer layer, and the inner layer were each formed of the following materials under the following conditions: 64 φ), a shrink-fit portion diameter of 660 φ, and an inner layer thickness of 100 mm.

However, the second outer layer contains 0.5% Ca-3i as Si.
Inoculated.

The first outer layer, second outer layer, and inner layer of the above components were successively centrifugally cast, followed by high-temperature diffusion heat treatment, standardization, and tempering, and the hardness described above was obtained.

As a result, the first outer layer had the target structure of special cast steel, and the second outer layer had a graphite steel structure with graphite.

In addition, a strong ductile cast iron material was obtained for the inner layer.

Note that the boundary between the first outer layer and the second outer layer was sound, and had a continuous structure with no difference in surface roughness or wear even if the surfaces had the same hole shape.

As described above, the multilayer roll for sheet pile rolling of the present invention includes a first outer layer forming a groove-shaped convex portion, a second outer layer forming a groove-shaped recess, and an inner layer forming a thick portion not subjected to rolling. It is constructed by assembling a sleeve consisting of three layers around a shaft, so the sleeve as a whole can reasonably satisfy the properties required for each part of the groove at the same time, and its rolling life can be extended. be.

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

In addition, in the above explanation, we have described an example of a roll in which a multilayer sleeve is assembled onto the shaft by shrink fitting, etc., but one roll,
That is, after casting the first outer layer and the second outer layer, it is of course possible to form one roll by integrally casting the inner layer and the shaft with ductile cast iron (core material).

Note that the technical idea of the present invention is similarly applied to rolls having many hole shapes in one roll.

[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 the multilayer roll for sheet pile rolling of the present invention. FIG. 6 is a diagram for explaining the relationship between the thicknesses of the first outer layer, the second outer layer, and the inner layer of the sleeve. 1...Shaft, 2...Sleeve, 3...
... Hole-shaped concave portion, 4... Hole-shaped convex portion, 9...
...First outer layer, 10... Second outer layer, 11...
...inner layer.

Claims (1)

[Claims] 1. A first outer layer forming a groove-shaped convex portion, a second outer layer forming a groove-shaped recess, and an inner layer forming a thick portion not subjected to rolling are metallurgically bonded. A multilayer roll for sheet pile rolling, characterized in that the sleeve is assembled onto a shaft. 2 The new diameter of the hole-shaped concave part of the sleeve is D4, and the first outer layer and the second
The boundary diameter of the outer layer is D3, and the diameter of the hole-shaped convex part of the sleeve is D2.
, the diameter of the same-hole type recess is D5, and the boundary diameter between the second outer layer and the inner layer is D6, the thickness of the first outer layer and the second outer layer is (D
2-50) >D”> (D4+20), (D5-20
)>D6. 3 The first outer layer is CO06-1.5, Si1. Below O,
Mn002~1.0, P 0005 or less, SO,
05 or less, Ni001~2.0, Cr005~2.0,
MOo, 1 to 1.0% by weight, the balance being substantially Fe
and is made of special cast steel having a hardness of Hs38-50, and the second outer layer is C1,0-2.0.5iO06-
3.0, Mn0.2-1.0, P O01 or less, S O
01 or less, Ni0.1-2.0, Cr0.5-1.0,
MOo, 1 to 1.0% by weight, the balance being substantially Fe
The inner layer is C2,8-3,8, Si 1,5-3.2, M
Contains n0.3-1.0, P O01 or less, SO,03 or less, Ni2.0 or less, Cr3.0 or less, Mo0.6 or less, Mg O,02-0.1 in each vehicle amount%, the balance is real 3. The multilayer roll according to claim 1 or 2, which is made of ductile cast iron which is essentially made of Fe and has a hardness of Hs 38 to 50.