JP2004066242A - Composite roll made of sintered hard alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite roll made of a sintered hard alloy, in which the outer layer used for rolling is formed from the sintered hard alloy and the performance can be exhibited in accordance with the service conditions of respective calibers even in the case a plurality of kinds of the calibers different in the sevice condition in rolling are arranged. <P>SOLUTION: This composite roll made of the sintered hard alloy in which the outer layer consisting of the sintered hard alloy is metallically joined on the outer peripheral surface of the inner layer consisting of steel or iron base material and the outer layer consists of at least two or more of different materials in the axial direction. The caliber is provided on the surface of the outer layer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite roll used for rolling bars, wires, flat materials, and the like made of metal such as iron and steel, in which an outer layer made of a cemented carbide is metal-bonded to the outer periphery of an inner layer made of a steel or iron material. .
[0002]
[Prior art]
In the rolling of bars, wires, flats, etc. made of metal such as iron and steel, several to more than a dozen cavities are used to form rolled products in the axial direction of the roll body from the intermediate stand to the finishing stand. Carbide rolls provided with excellent abrasion resistance and skin abrasion resistance are widely used.
[0003]
For example, Japanese Patent Publication No. 58-39906 describes a roll for rolling a wire made of a WC cemented carbide of WC-Co-Ni-Cr. This roll for wire rod rolling is a small-sized sleeve roll obtained by sintering a cemented carbide alone, and is fitted to a steel roll shaft having excellent toughness at a shrink fitting ratio of about 0.1 / 1000. The rolls are mechanically assembled by pressing and fixing the side surfaces of the rolls with a fixing ring, a spacer ring, or the like. The dimensions of this type of cemented carbide sleeve roll are relatively short with an outer diameter of 100 to 500 mm and a length in the direction of the rotation axis of about 10 to 300 mm.
[0004]
In the case of a roll in which a cemented carbide sleeve is fitted to a roll shaft in this way, a large number of members such as fixing rings, spacer rings, disc springs, and nuts are required, the assembly structure is complicated, and high assembly accuracy is required. Since it is required, there is a problem that man-hours and costs related to assembly are required. In addition, there is a problem that the portion occupied by the cemented carbide, that is, the portion that can be used for rolling is less than half the length of the roll body, which is not efficient.
[0005]
Furthermore, since the cemented carbide has a high thermal conductivity, the temperature of the cemented carbide tends to increase during rolling use, the heat is easily transmitted to the steel roll shaft, and the roll shaft expands significantly. Therefore, since the thermal expansion coefficient of the cemented carbide is smaller than that of steel, a tensile stress is applied to the cemented carbide sleeve in the radial direction and the axial direction. In the case where the interference at the time of shrink fitting is large, if the tensile stress in the radial direction becomes too high, there is a possibility that a crack may be caused from the inner surface of the cemented carbide sleeve. On the other hand, when the interference at the time of shrink fitting is so small that there is a concern about such cracking, the cemented carbide sleeve may slip during rolling.
[0006]
In addition, the cemented carbide alone has a problem that a large and long sleeve roll cannot be manufactured because the compact is easily deformed by the influence of its own weight during sintering.
[0007]
In order to overcome the drawbacks of the assembling type super hard roll, for example, Japanese Patent Application Laid-Open No. 10-8212 proposes a composite roll in which a super hard alloy and a steel material are metallically joined. This means that at least one or two or more of hard particles of carbides, nitrides and carbonitrides of elements IVa to VIa of the periodic table are added to the outer periphery of the sleeve forming the inner layer made of steel at 60 to 90% by weight. And a cemented carbide outer layer formed by sintering a mixed powder consisting essentially of at least one or two or more metal powders of Fe, Ni, Co, Cr, Mo and W and simultaneously diffusion-bonding the mixed powder. A composite sleeve in which a circumferential compressive residual stress of 100 MPa or more is applied to the outer layer surface is fitted and fixed to a roll shaft. JP-A-10-8213 also proposes a composite roll having a solid structure in which a cemented carbide and a solid shaft made of steel are metallically joined.
[0008]
[Problems to be solved by the invention]
This type of cemented carbide composite roll eliminates the need for fixing rings, disc springs, nuts, etc. in conventional assembling cemented carbide rolls, and can be used for rolling because the entire surface of the roll body length is composed of an outer layer. Can be expanded. For this reason, a larger number of calipers can be provided on the surface of the roll body than in the conventional case, and there is no restriction on the location.
[0009]
Therefore, various types of calipers can be provided on the same roll body surface in accordance with the rolling amount and operating conditions, but in practice, the load conditions such as rolling temperature and rolling speed differ depending on the type of calipers, The optimum roll material corresponding to this also differs. However, in the conventional cemented carbide composite roll, since the entire cemented carbide part forming the outer layer used for rolling is made of one type of material, it is not possible to use an optimum material for each caliber. There is a problem that it is not suitable for use in which a caliber is arranged.
[0010]
Therefore, an object of the present invention is to form the outer layer used for rolling with a cemented carbide, and even when arranging a plurality of types of calipers having different rolling use conditions, sufficient performance according to the use conditions of each caliber. An object of the present invention is to provide a composite roll made of a cemented carbide which can be used.
[0011]
[Means for Solving the Problems]
The cemented carbide composite roll of the present invention has an outer layer made of a cemented carbide metal-bonded to the outer periphery of an inner layer made of a steel or iron material, and the outer layer is made of at least two or more different materials in the roll axis direction. It is characterized by becoming. The composite roll of the present invention is characterized in that a caliber is provided on the surface of the outer layer.
[0012]
[Action]
According to the present invention, the outer layer made of a cemented carbide is metal-bonded to the outer periphery of the inner layer made of a steel or iron-based material, so that the roll body, that is, the entire outer layer can be used for rolling. Not only can it be removed, but it can be provided at any position with no restriction on the arrangement position.
[0013]
In addition, since the cemented carbide forming the outer layer of the roll is configured to differ by at least two types in the roll axis direction, when the caliber is provided, the caliber can be formed of an optimum material for each rolling use condition. In other words, different stand calipers are provided in the roll axis direction, and can be used as a roll for multiple stands. Therefore, according to the present invention, the possible rolling amount per roll can be increased, the number of rolls held can be reduced, and assets can be compressed and the roll storage space can be reduced.
[0014]
In the present invention, when metal bonding between the outer layer made of a cemented carbide and the inner layer made of a steel or iron-based material, in order to secure the bonding strength between the two, a cemented carbide or metal is placed between the outer layer and the inner layer. May be joined by interposing at least one or more intermediate layers made of.
[0015]
The method of manufacturing the cemented carbide as the outer layer with a different material in the roll axis direction is to install an inner layer made of a steel or iron-based material in a HIP can made of steel, and have a target composition of each target between the two. After the sintering, the cemented carbide powder is sequentially filled so as to be at a predetermined position, the HIP can is sealed by welding, and then sintered and integrated by HIP processing. Further, as another method, a plurality of hollow compacts of a cemented carbide having respective target compositions are prepared in advance with a predetermined length, and these are stacked so as to be fitted around an inner layer made of a steel or iron material. After that, it may be sintered and integrated, or the whole may be sealed in a HIP can and integrated by HIP processing.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
A HIP can composed of steel having an outer diameter of 380 mm and a length of 600 mm is set around a hollow cylindrical forged steel inner layer having an outer diameter of 300 mm, an inner diameter of 180 mm and a length of 700 mm, and the outer surface of the inner layer and the inner surface of the HIP can First, 150 kg of a mixed powder of 85% of WC powder having an average particle size of 5 μm and 15% of Co powder having an average particle size of 2 μm as a cemented carbide powder for the first outer layer in a void formed between Filled. Next, from above the filled hard metal powder for the first outer layer, 75% of WC powder having an average particle diameter of 7 μm and Co having an average particle diameter of 2 μm 150 kg of a mixed powder of 25% of the powder was filled. In other words, the first outer layer cemented carbide powder and the second outer layer cemented carbide powder are adjacent to each other in the roll axis direction.
[0017]
After filling, the HIP can was welded and sealed with a steel lid, and then deaerated with a vacuum pump at 700 ° C. After confirming that no leak occurred in the HIP can, HIP treatment was performed at 1300 ° C. and 1000 atm. After cooling, the HIP can was processed and removed, and ultrasonic inspection was performed to confirm that the bonding between the outer layer composed of the first outer layer and the second outer layer and the inner layer was sound. The structure of the outer layer of the roll was examined, and it was confirmed that the first outer layer and the second outer layer were soundly joined in the roll axis direction.
[0018]
FIG. 1 shows the sleeve roll of the present invention thus obtained. In FIG. 1, 1 is a first outer layer, 2 is a second outer layer, and 3 is an inner layer. In the roll axis direction, the first outer layer 1 and the second outer layer 2 are joined. In addition, for convenience, the joining boundary between the first outer layer 1 and the second outer layer 2 is drawn, but a clear line does not appear in an actual roll.
[0019]
Then, the inner diameter of the sleeve roll of the present invention is processed and shrink-fitted to a chromium molybdenum steel shaft. The first outer layer is an oval caliber for a stand before finishing, and the second outer layer is an oval caliber for an intermediate stand. A plurality of each were machined and provided to complete the cemented carbide composite roll of the present invention.
[0020]
(Example 2)
First, a hollow sleeve having an outer diameter of 358 mm, an inner diameter of 256 mm, and a length of 350 mm made of a sintered body of a cemented carbide having a composition of 85% by weight of WC and 15% by weight of Co was used for the first outer layer. As a result, a hollow sleeve having an outer diameter of 358 mm, an inner diameter of 256 mm, and a length of 350 mm made of a sintered body of a cemented carbide having a composition of WC 75% by weight and Co 25% by weight was produced.
[0021]
Next, a HIP can composed of steel having an outer diameter of 360 mm and a length of 700 mm is placed around a hollow cylindrical forged steel inner layer having an outer diameter of 250 mm, an inner diameter of 150 mm, and a length of 730 mm. The hollow sleeve for the first outer layer was inserted into the space formed between the inner sleeve and the inner surface of the first outer layer, and the hollow sleeve for the second outer layer was stacked and inserted immediately above the first outer sleeve.
[0022]
Thereafter, the HIP can was welded and sealed with a steel lid, and then deaerated by a vacuum pump at 700 ° C. After confirming that no leak occurred in the HIP can, HIP treatment was performed at 1300 ° C. and 1000 atm. After cooling, the HIP can was processed and removed, and ultrasonic inspection was performed to confirm that the bonding between the outer layer composed of the first outer layer and the second outer layer and the inner layer was sound. The structure of the outer layer of the roll was examined, and it was confirmed that the first outer layer and the second outer layer were soundly joined in the roll axis direction.
[0023]
The inner diameter of the sleeve roll of the present invention thus obtained is processed and shrink-fitted to a chromium molybdenum steel shaft. The first outer layer is an oval caliber for a stand before finishing, and the second outer layer is an intermediate stand. A plurality of oval calipers were provided and machined, respectively, to complete a cemented carbide alloy roll of the present invention.
[0024]
(Example 3)
First, for the first outer layer, a 380 mm in outer diameter, 300 mm in inner diameter, and 270 mm in length made of a pre-sintered body of a cemented carbide having a composition of 85% by weight of WC and 15% by weight of Co (pre-sintered at 900 ° C.). The hollow sleeve is used for the second outer layer, and has an outer diameter of 380 mm, an inner diameter of 300 mm, and a length of a pre-sintered body of a cemented carbide having a composition of 75 wt% WC and 25 wt% Co (pre-sintered at 900 ° C.). A hollow sleeve having a length of 270 mm is further used as a third outer layer, and has an outer diameter of 380 mm and an inner diameter of a cemented carbide pre-sintered body (temporarily sintered at 900 ° C.) having a composition of WC 70 wt% and Co 30 wt%. A hollow sleeve having a length of 300 mm and a length of 270 mm was produced.
[0025]
A hollow sleeve for a first outer layer is fitted and inserted into the outer periphery of a hollow cylindrical inner layer of forged steel having an outer diameter of 250 mm, an inner diameter of 150 mm, and a length of 730 mm. The second outer layer hollow sleeve is inserted and stacked, and the third outer layer hollow sleeve is inserted immediately above the second outer layer hollow sleeve and stacked, and then fired at 1320 ° C. in a vacuum sintering furnace. Tied.
[0026]
After cooling, it was confirmed by ultrasonic inspection that the bonding between the outer layer composed of the first outer layer, the second outer layer, and the third outer layer, and the inner layer was sound. Further, the structure of the outer layer of the roll was examined, and it was confirmed that the first outer layer, the second outer layer, and the third outer layer were soundly joined in the roll axis direction.
[0027]
The inner diameter of the sleeve roll of the present invention thus obtained is worked and shrink-fitted to a chromium molybdenum steel shaft. The first outer layer is an oval caliber for a stand before finishing, and the second outer layer is an intermediate stand. A plurality of oval calipers for the intermediate stand are provided on the third outer layer, and a composite roll made of a cemented carbide of the present invention is completed.
[0028]
【The invention's effect】
Since the cemented carbide forming the outer layer of the roll is configured to differ by at least two types in the roll axis direction, when the caliber is provided, the caliber can be formed of an optimum material for each rolling use condition. Therefore, the possible rolling amount per roll can be increased, the number of rolls held can be reduced, and the assets can be compressed and the roll storage space can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a sleeve roll of the present invention.
[Explanation of symbols]
1 first outer layer, 2 second outer layer, 3 inner layer

Claims (2)

A cemented carbide composite, wherein an outer layer made of a cemented carbide is metal-bonded to the outer periphery of an inner layer made of a steel or iron-based material, and the outer layer is made of at least two or more different materials in the roll axis direction. roll. The cemented carbide composite roll according to claim 1, wherein the outer layer is a roll provided with a caliber on a surface thereof.

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