JPH05123854A - Manufacture of composite roll - Google Patents

Abstract

PURPOSE:To satisfactorily perform roll-bending, absorb the impact force of an accident such as over drawing reduction during rolling, reduce the compressive load on the outer layer and prevent the generation of a crack in the outer layer by using a DCI material for a shaft member of a composite roll. CONSTITUTION:The shaft member 2 is concentrically and continuously lowered in a cylindrical mold, a molten metal for the outer layer is continuously poured into the clearance between the mold and the shaft member 2 and solidified at the lower part of the mold. The outer layer 3 is integrally welded and formed on the outer peripheral surface of the shaft member. In the method of manufacturing the composite roll, a DCI material is used for the shaft member 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite roll by the so-called continuous overlay welding method.

[0002]

2. Description of the Related Art As shown in FIG. 1, a so-called continuous build-up welding method is a suitable manufacturing method of a composite roll 1 in which an outer layer 3 which is a rolling layer is integrally formed by welding on an outer peripheral surface of a shaft member 2. is there. This method is disclosed in JP-B-44-4903, and as shown in FIG. 2, an annular water-cooling mold 16 through which cooling water flows in the direction of the arrow in the figure, and an annular ring made of graphite-based refractory material. A buffer mold 15 formed, and a high-frequency conductive heating coil 21 is built-in, and a heating mold 13 formed in an annular shape with a refractory material is concentrically connected upward in this order to form a cylindrical mold 12. Provided, the shaft member 11 is inserted concentrically with respect to the mold 12, the molten metal 18 of the outer layer material is continuously injected into the gap between the mold 12 and the shaft member 11, and the shaft member 11 is continuously lowered. This is a method for producing a composite roll by solidifying the molten metal 18 with a buffer mold 15 and a water cooling mold 16 and continuously overlaying the outer layer 17 on the outer peripheral surface of the shaft member 11. In the figure, numeral 20 is a shaft member for preventing the poured molten metal from flowing out by being positioned at the lower end opening of the heating mold 13 before the molten metal is poured
11 A steel support plate that is provided on the outer peripheral surface. 19 is a flux that covers the surface of the molten metal to prevent oxidation and keep it warm.
Reference numeral 14 is a steel plate for blocking induction heating of the high-frequency induction heating coil 21 from reaching the buffer type, 22 is a water passage for cooling water of the coil, and 23 is a preheating coil for the shaft member.

By adopting the above-mentioned continuous build-up welding method, the outer layer can be easily welded to the outer periphery of the shaft member, and the toughness of the shaft member is not impaired at the time of welding. Occurrence of cracks and breakage has been suppressed. The material of the shaft member is graphite cast steel (C: 1-2 wt%), which has excellent toughness, and cast steel.
(C: 1.0 wt% or less), forged steel, carbon steel for machine structure, low alloy steel for machine structure (SCM material, SNCM material, etc.).

[0004]

Since the shaft member used in the continuous build-up welding method is a steel material, the Young's modulus is 20000 to
It is as high as 23000 kg / mm ² , so the composite roll manufactured by the above method has less absorption of impact force in the shaft member against abnormal load during rolling use, so-called narrowing accident, and in some cases cracks occur in the outer layer. There was a problem.
In addition, it is not necessary to have toughness (a tensile strength of 60 kg / mm ² or more can easily be obtained with steel) to the extent that it must be steel as the shaft member of the current rolling rolls, and tensile strength of about 40 kg / mm ² is required. It is practically sufficient if it has strength.

Further, in carrying out the continuous build-up welding method, it is necessary to preheat the shaft member to 600 ° C. or higher in order to make the welding of the outer layer sound. Further, during continuous build-up welding, the shaft member is also heated to a high temperature. Therefore, an oxide film is formed on the surface of the shaft member, and the soundness of the welded portion is hindered.
In order to prevent the formation of an oxide film, an attempt was made to coat the outer peripheral surface of the shaft member with a flux, but the shaft member is easily peeled off during handling or heating, and the sufficient effect is not obtained.

The present invention has been made in view of the above problems, and when the composite roll is used for rolling, the material of the shaft member is DC.
By setting I, the impact force at the time of narrowing down is absorbed,
Aiming to provide a composite roll that does not generate cracks in the outer layer, further, during continuous build-up welding, it is difficult for an oxide film to be formed on the outer peripheral surface of the shaft member, and sound welding of the outer layer can be obtained. It is an object of the present invention to provide a method for producing a composite roll.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention continuously lowers a shaft member concentrically in a cylindrical mold, and continuously melts an outer layer material in a gap between the mold and the shaft member. In a method of manufacturing a composite roll in which the outer layer is welded and integrally formed on the outer peripheral surface of the shaft member by pouring and solidifying at the lower part of the mold, the shaft member is made of a DCI material, and further on the outer peripheral side surface of the shaft member. This is a method of applying Ni plating in advance.

[0008]

[Function] Young's modulus of DCI material is 15000 to 18000 kg / mm ²
Since it is lower than the steel material, the composite roll having the shaft member made of the DCI material as the inner layer works well with the roll bender, and at the same time, the shaft member absorbs the impact force at the time of a narrowing accident during the rolling operation, thereby compressing the outer layer. The load is reduced so that no cracks occur in the outer layer.

Ni is a material having excellent oxidation resistance.
1100 ° C because the plating layer covers the outer peripheral surface of the shaft member
To a certain extent, the surface oxidation of the shaft member can be prevented.
The Ni plating layer has considerably higher strength than the flux layer and has excellent bonding strength, so there is no risk of peeling during handling up to continuous build-up work, and corrosion prevention and contamination even during long-term storage of shaft members. It is effective in prevention.

[0010]

EXAMPLES Material of shaft member used in the present invention, that is, D
The CI has a known chemical composition (wt%, the balance being substantially Fe). ○ DCI material C: 2.8 to 3.8%, Si: 0.8 to 3.0%, Mn:
0.1 to 1.0%, P: 0.1% or less, S: 0.03% or less, Ni:
3.0% or less, Cr: 1.0% or less, Mo: 1.0% or less, Mg:
0.01 to 0.1%, and the thickness of the Ni plating layer formed on the outer peripheral surface of the shaft member may be about 2 μm or more, and 10 to 20 μm is sufficient. If the thickness is made thicker than that, there is no particular problem in terms of effect, but the plating cost becomes high and it is not economical. As a plating method, electrochemical plating (wet plating) is generally used, but dry plating such as spray coating or vacuum deposition may be used. The plating layer may be formed on the outer peripheral surface of the shaft member on which at least the outer layer is welded.

Various roll materials are used as the material of the outer layer material. For example, a high Cr cast iron material and a high C high speed steel material can be exemplified. High C high speed steel has excellent wear resistance,
It is a suitable material that does not easily chip. A typical chemical composition (wt%, balance substantially Fe) is shown below. ○ High Cr cast iron material C: 1.0 to 3.2%, Si: 0.3 to 1.5%, Mn:
0.5 to 2.0%, P: 0.1% or less, S: 0.1% or less, Ni:
0.2 to 4.0%, Cr: 5 to 25%, Mo: 0.1 to 4.0% ○ High C high speed steel C: 1.5 to 2.5%, Si: 0.2 to 1.0%, Mn:
1.5% or less, P: 0.1% or less, S: 0.1% or less, Ni:
2.0% or less, Cr: 3 to 8%, Mo: 1 to 10% and W: 1 to 10%, V: 3 to 10%, Co:
1-10%, Nb: 1-5%, and 1 or 2 or more types.

During continuous build-up welding of the outer layer, the Ni plating layer dissolves in the outer layer molten metal, but the amount of dissolution is very small and there is no risk of deteriorating the material properties of the outer layer. Hereinafter, specific manufacturing examples will be described. (1) Machine the outer circumference of the DCI bar (Table 1) to give an outer diameter of φ30
A shaft member of 0 mm was manufactured. Then, a Ni plating layer having a thickness of 15 μm was formed on the outer peripheral surface by electroplating. (2) Using the apparatus shown in FIG. 2, the preheating coil was first moved in the axial direction of the shaft member to preheat the entire shaft member to about 600 ° C. Next, the output of the preheating coil was increased so that the surface temperature became about 1000 ° C., and the receiving plate protruding from the shaft member was lowered while preheating so that it came to a position where it closed the lower end opening of the heating die. (3) Molten metal having the chemical composition shown in Table 1 below was poured into the gap between the shaft member and the heating die, and the molten metal surface was covered with flux. At this time, the molten metal temperature was 1480 ° C.

In order to prevent the poured molten metal from solidifying in the heating mold, it was heated and stirred by the high frequency induction heating coil in the mold.

[0014]

[Table 1]

(4) Immediately after the molten metal is poured, the shaft member is moved to 30 mm /
The mold was lowered at a speed of a minute, the molten metal was solidified by a buffer mold and a water-cooled mold, the outer layer was overlay-molded, and the outer peripheral surface of the shaft portion was welded and integrated. On the other hand, since the surface of the molten metal in the heating mold also descends simultaneously with the lowering of the shaft member, the molten metal was continuously injected and the molten metal surface was held at a fixed position of the heating mold. (5) After pouring a predetermined amount of the molten metal, the pouring of the molten metal was stopped and the shaft member was extracted below the mold to obtain a roll material having an outer layer formed on the outer peripheral surface of the shaft member. (6) When the roll material was subjected to an ultrasonic flaw detection test, it was confirmed that the outer peripheral surface of the shaft member and the outer layer were welded over the entire surface. Further, when the cross section was subjected to a fracture examination, the soundness of the welded portion was confirmed.

[0016]

As described above, according to the method of manufacturing a composite roll of the first aspect of the present invention, firstly, as the shaft member, D
Since CI material is used, the roll bender works well,
The shaft member well absorbs impact force such as a narrowing accident during rolling use, and the compressive load of the outer layer is reduced, so that the problem that cracks occur in the outer layer can be reduced. Also, since DCI is cheaper, a composite roll can be provided at a lower cost. Further, in the conventional steel shaft member, since the coupling is made of steel, seizure and galling of the uobula portion are likely to occur, but in the present invention, since the shaft member is DCI,
There are no such drawbacks.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the following effect is exhibited. That is, when the outer layer is formed by continuous build-up welding, the outer peripheral surface of the shaft member is preliminarily plated with Ni, so that N having excellent oxidation resistance is obtained.
The i-plated layer prevents surface oxidation of the shaft member and ensures the soundness of the welded portion. Further, since the Ni plating layer has high strength and is difficult to peel off, it is easy to handle.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a composite roll.

FIG. 2 is a cross-sectional explanatory view of a continuous overlay welding device for carrying out the present invention.

[Explanation of symbols]

 2 Shaft member 3 Outer layer 11 Shaft member 17 Outer layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Kimura 64, Nishimukaijima-cho, Amagasaki City, Hyogo Prefecture Kubota Amagasaki Factory (72) Inventor Kei Shikata, Kubota Amagasaki Factory 64 Nishimukojima-cho, Amagasaki City, Hyogo Prefecture Within

Claims (2)

[Claims] 1. An outer peripheral surface of a shaft member, in which a shaft member is continuously and concentrically lowered in a cylindrical mold, and a molten outer layer material is continuously injected into a gap between the mold and the shaft member and solidified at a lower part of the mold. A method of manufacturing a composite roll, wherein an outer layer is integrally formed by welding, wherein the shaft member is made of a DCI material. 2. The method of manufacturing a composite roll according to claim 1, wherein the outer peripheral side surface of the shaft member is previously plated with Ni.