JP6489405B2 - Cemented carbide composite sleeve roll - Google Patents

Description

The present invention relates to a cemented carbide composite sleeve roll used for rolling metal materials such as wires and rods.

When rolling metal materials such as wires and rods, it is made of cemented carbide with an outer layer made of tungsten carbide (WC) cemented carbide with excellent wear resistance on the outer periphery of the inner layer made of metal material with excellent toughness A composite sleeve roll is used. The sleeve roll is fitted to the outer periphery of the roll shaft member and is detachably assembled by tightening or shrink fitting with a tightening member. As is well known, the WC cemented carbide is a sintered alloy in which WC is bonded with a metal element such as Co, Ni, or Cr.

  For example, in Patent Document 1, a cast iron ring having a thickness of 0.3 to 5 mm is press-fitted into the inner periphery of a ring-shaped cemented carbide having a predetermined effective thickness, and a cylinder or a cylinder is inserted into the inner periphery of the cast iron ring. The steel is cooled and fitted, and then treated in a reducing or neutral atmosphere or in a vacuum at a temperature that does not exceed the melting point of the cast iron, and the cast iron is bonded to the outer hard metal and the inner steel. A composite roll made of cemented carbide in which the three metals are integrated by diffusion is described. According to the invention described in Patent Document 1, a hard-working cemented carbide is used only for the required working surface of a roll, and the other is a steel material that is cheaper, lighter, more rigid, and easier to machine than cemented carbide. It is possible to reduce the processing cost and the material cost because it is light weight with few breakage.

  In Patent Document 2, in a rolling roll formed by fitting and fixing a ring to be rolled on the outer periphery of a shaft, the ring is made of an outer ring portion made of cemented carbide and a material other than cemented carbide such as steel. And a rolling roll formed with an inner ring portion fitted and fixed to the inner periphery of the outer ring portion, and forming a key portion that fits into the inner periphery of the inner ring portion and the outer periphery of the shaft. Have been described. According to the invention described in Patent Document 2, a slip accident can be reliably prevented without breaking the ring, and the manufacturing cost of the rolling roll can be reduced and the tightening operation of the ring can be reduced.

  Patent Document 3 describes a cylindrical ring base made of steel material with excellent toughness, and wear resistance of super steel material or high-speed steel filled in an annular concave groove formed on the outer peripheral surface of the base material. A high-alloy steel material powder excellent in the above is sintered by hot isostatic pressing, and a composite ring roll comprising a rolling ring that is diffusion-bonded to the inner surface of a groove is described. According to the invention described in Patent Document 3, the ring base is a steel material, although the portion in contact with the rolled material is formed of a WC-based cemented carbide material, etc., and has good workability, and is tough and welded. The effect is also good.

  Patent Document 4 discloses a composite roll for rolling in which an outer layer material made of a WC-based cemented carbide is substantially directly metal-bonded to the outer periphery of an inner layer material made of an iron-based alloy containing C: 0.5% by weight or more. In the bending test based on JIS R1601, a composite roll for rolling is described in which the bending strength of the bending test piece including the boundary joint portion between the outer layer material and the inner layer material is 600 MPa or more. According to the invention described in Patent Document 4, there is no fragile η phase at the boundary joint, and a highly reliable boundary joint can be obtained.

JP 58-68488 A Japanese Patent Laid-Open No. 60-24208 Japanese Patent Publication No. 5-55202 JP 2003-275809 A

Conventional cemented carbide composite sleeve rolls have the advantages that the outer layer made of cemented carbide is excellent in wear resistance, the inner layer made of steel is excellent in toughness and easy to machine. However, in Patent Document 1, after a cast iron ring is press-fitted into a ring-shaped cemented carbide, a cylindrical steel material is cooled and fitted into the inner periphery of the cast iron ring. Therefore, it is difficult to obtain a strong joint because the joint integration is complicated.

In Patent Document 2, since the outer ring portion made of cemented carbide and the inner ring portion made of steel are mechanically fitted and fixed, it cannot be said that the bonding between the outer ring portion and the inner ring portion is sufficiently strong. There was a risk that the outer and inner ring portions would move and shift relatively.

In Patent Document 3, the cemented carbide is diffusion-bonded to the outer peripheral surface of the ring base (inner layer) made of steel material, so that the bonding is strong. However, when the cemented carbide is diffusion-bonded to the outer peripheral surface of the steel material, the carbon activity is increased. Since carbon diffuses and moves from the outer layer to the inner layer of a high-hardness cemented carbide, the η phase appears at the joint boundary and the material becomes brittle. For this reason, there are cases where the bonding reliability between the outer layer and the inner layer is not sufficient, and there is a problem that the outer layer tends to peel from the bonded portion after bonding. Patent Document 4 has a problem that the inner layer is likely to break because the residual stress of the inner layer becomes too high.

  In view of the above problems, an object of the present invention is to provide a cemented carbide composite sleeve roll in which the bonding reliability between an inner layer made of an iron-based material having excellent toughness and an outer layer made of a cemented carbide is improved.

The composite sleeve roll made of cemented carbide according to the present invention is a composite sleeve made of cemented carbide in which an outer layer made of cemented carbide having a rolled formed part formed on the outer peripheral surface is metal-bonded to the outer periphery of a hollow inner layer made of iron-based material. In the roll, the inner layer is made of an iron-based material containing 0.65 to 1.2% by mass of C and 1.8 to 7.5% by mass of Ni.

  In the cemented carbide composite sleeve roll of the present invention, the inner layer preferably contains 3% by mass or less of Cr and 1.5% by mass or less of Mo.

In the cemented carbide composite sleeve roll of the present invention, the inner layer preferably contains 1.0% by mass or more in total of any one or more of Cr, Ni, Mo, V, W, Ti, and Nb.

In the cemented carbide composite sleeve roll of the present invention, the tensile strength at the boundary between the outer layer and the inner layer is preferably 600 MPa or more. The fatigue strength at the boundary between the outer layer and the inner layer is preferably 200 MPa or more.

  In the cemented carbide composite sleeve roll of the present invention, it is preferable that the outer layer made of the cemented carbide contains 70 to 88% by mass of WC.

  It is preferable that the roll is constituted by assembling the cemented carbide composite sleeve roll of the present invention detachably on the outer periphery of the roll shaft material.

  According to the cemented carbide composite sleeve roll in which the inner layer made of an iron-based material having excellent toughness and the outer layer made of a cemented carbide according to the present invention are joined, the super-improved joining reliability can be applied to long-term rolling. A hard alloy composite sleeve roll can be obtained.

It is a schematic sectional drawing of the composite sleeve roll made from the cemented carbide of this invention. It is a schematic sectional drawing which shows the example which assembled | attached the cemented carbide alloy composite sleeve roll of this invention to the shaft material. It is drawing for demonstrating the method to manufacture the cemented carbide composite sleeve roll of this invention by a diffusion bonding method. It is a schematic sectional drawing explaining the manufacturing method which joins the cemented carbide composite sleeve roll of this invention by HIP method. It is drawing explaining the joining method in Example 1 and Example 2 of this invention. It is drawing explaining the tensile test piece of Example 2 of this invention.

An embodiment for carrying out the present invention will be specifically described. The present invention is not limited to the following embodiments, and modifications and improvements are appropriately added to the following embodiments based on ordinary knowledge of those skilled in the art without departing from the technical idea of the present invention. Are also included within the scope of the present invention.

FIG. 1 is a schematic sectional view of a cemented carbide composite sleeve roll of the present invention. The cemented carbide composite sleeve roll 1 of the present invention is obtained by directly metal-bonding a cemented carbide outer layer 2 and a hollow inner layer 3 made of an iron-based material. On a part of the outer peripheral surface of the outer layer 2, a groove-shaped rolled forming portion 2a with which the material to be rolled comes into contact is formed. The inner layer 3 has a hollow portion 5. 3 a is the inner peripheral surface of the inner layer 3. Reference numeral 4 denotes a boundary portion where the outer layer 2 and the inner layer 3 are joined. Rolling is performed by passing a material to be rolled such as a bar wire made of a metal material between a pair of cemented carbide composite sleeve rolls.

(1) Outer layer The outer layer 2 made of cemented carbide of the cemented carbide composite sleeve roll of the present invention is a known material, and WC, which is a hard particle, is bonded to a metallic element such as Co, Ni, Cr, Fe, etc. As well as WC, it may contain carbides such as Ti, Ta, and Nb. From the viewpoint of achieving both wear resistance and mechanical strength of the outer layer, the average particle size of WC is preferably 3 to 10 μm, and the content of WC is preferably 70 to 88% by mass. The lower limit of the WC content is more preferably 72% by mass. The upper limit of the WC content is more preferably 85% by mass. The maximum thickness of the outer layer 1 is set in a range of 5 to 50 mm in consideration of gradual wear due to rolling.

(2) Inner layer The inner layer 3 of the cemented carbide composite sleeve roll of the present invention is an iron-based material containing 0.65 to 1.2% by mass of C (carbon) and 1.8 to 7.5% by mass of Ni.

When joining the outer layer made of cemented carbide and the inner layer made of iron-based material, due to the difference in carbon activity between the two, carbon diffuses and moves at the joining interface during sintering joining, and the carbon activity of the cemented carbide is reduced. It is known that when the ratio is higher, carbon diffuses from the cemented carbide near the bonding interface to the inner layer side, so that the carbon in the cemented carbide decreases. As a result, the η phase, which is a carbide having a low carbon composition, appears in this portion, and the mechanical strength of the cemented carbide may deteriorate.

As a result of earnestly conducting joint experiments between cemented carbide and iron-based alloys using an inner layer made of various iron-based materials, if the carbon content of the inner layer is 0.65% by weight or more, carbon diffusion from the cemented carbide is almost impossible. Thus, it was confirmed that the generation of η phase can be surely prevented. When the carbon content of the inner layer exceeds 1.2%, harmful graphite is generated at the boundary portion 4 between the outer layer 2 and the inner layer 3 to reduce the bonding strength. The lower limit of the carbon content of the inner layer is more preferably 0.7% by mass and even more preferably 0.75% by mass. The upper limit of the carbon content of the inner layer is preferably 1.0% by mass.

In addition, it was confirmed that the internal residual stress of the inner layer after joining can be controlled and the strength of the inner layer itself can be ensured by using an iron-based material in which the inner layer contains 1.8 to 7.5% by mass of Ni. This is because if the Ni content is less than 1.8% by mass, the residual stress of the inner layer becomes too high and the inner layer may be destroyed. Further, when Ni exceeds 7.5% by mass, the strength of the inner layer becomes low, and it becomes impossible to secure a tensile strength of 600 MPa at the boundary between the outer layer and the inner layer, which will be described later. The lower limit of the Ni content is more preferably 1.9% by mass, and further preferably 2% by mass. The upper limit of the Ni content is preferably 6% by mass, and more preferably 5% by mass.

As explained above, a cemented carbide composite sleeve roll having sufficient bonding strength by using an iron-based material containing 0.65 to 1.2 mass% of C (carbon) in the inner layer 3 and 1.8 to 7.5 mass% of Ni. Can be obtained.

The inner layer 3 preferably contains 3% by mass or less of Cr and 1.5% by mass or less of Mo. This is because if the Cr content exceeds 3% by mass, the hardness of the inner layer becomes too high and becomes brittle and the inner layer may be destroyed. The lower limit of the Cr content is preferably 0.01% by mass, and more preferably 0.03% by mass. The upper limit of the Cr content is more preferably 1.5% by mass. This is because if the Mo content exceeds 1.5% by mass, the hardness of the inner layer becomes too high and becomes brittle and the inner layer may be destroyed. The lower limit of the Mo content is preferably 0.01% by mass, and more preferably 0.05% by mass. The upper limit of the Mo content is more preferably 1% by mass.

Furthermore, the inner layer 3 preferably contains 0.5 to 2% by mass of Si and 0.1 to 0.9% by mass of Mn. Si in the inner layer 3 has a deoxidizing effect and has an effect of increasing quenching curability, so 0.5% by mass or more is preferable, but if it exceeds 2% by mass, the toughness may be deteriorated, so 2% by mass or less Is preferred. Similarly, Mn of the inner layer 3 has a deoxidizing effect and has an effect of increasing quenching curability, so 0.1% by mass or more is preferable, but if it exceeds 0.9% by mass, the toughness may be deteriorated. 0.9 mass% or less is preferable. Furthermore, the inner layer 3 may contain V, Nb, Co, W, Cu, etc. as inevitable impurities.

In the cemented carbide composite sleeve roll of the present invention, the tensile strength at the boundary between the outer layer and the inner layer is preferably 600 MPa or more. This is because if the tensile strength at the boundary between the outer layer and the inner layer is 600 MPa or more, it is possible to prevent the outer layer and the inner layer from peeling even when used for a long-term rolling. The tensile strength at the boundary between the outer layer and the inner layer is more preferably 700 MPa or more.

The fatigue strength at the boundary between the outer layer and the inner layer is preferably 200 MPa or more. This fatigue strength refers to tensile fatigue strength. This is because, if the fatigue strength at the boundary between the outer layer and the inner layer is 200 MPa or more, it is possible to prevent the outer layer and the inner layer from being separated after bonding. The fatigue strength at the boundary between the outer layer and the inner layer is more preferably 250 MPa or more.

(3) Bonding The composite sleeve roll made of cemented carbide according to the present invention has an outer layer made of cemented carbide and an inner layer made of an iron-based material containing 0.65 to 1.2% by mass of C and 1.8 to 7.5% by mass of Ni. This is the structure. Accordingly, it is sufficient that the interface between the outer layer and the inner layer is bonded without any gap, and bonding can be performed using a method such as a diffusion bonding method or an HIP method.

[Diffusion bonding method]
FIG. 3 is a drawing for explaining a method of manufacturing the cemented carbide composite sleeve roll of the present invention by a diffusion bonding method.

As shown in FIG. 3, a hollow cylindrical inner layer 3 is placed on a base 11. Separately prepared outer layer 2 made of cemented carbide is placed on cradle 12 and arranged and fitted on the outer peripheral side of inner layer 3. The outer layer 2 made of cemented carbide has a smaller thermal expansion coefficient than the inner layer 3 that is an iron-based material, so that an appropriate surface pressure acts on the interface between the outer layer 2 and the inner layer 3 when heated to the bonding temperature. A gap is formed at the time of placement at room temperature. After that, with the outer layer 2 and the inner layer 3 arranged as shown in FIG. 3, diffusion bonding is performed by heating in an atmosphere of any of inert gas, reducing gas, reduced pressure, and vacuum. A composite sleeve roll made of cemented carbide with diffusion bonded to is obtained. The bonding temperature of diffusion bonding is 1000 to 1320 ° C. As described above, the outer layer 2 made of cemented carbide has a smaller coefficient of thermal expansion than the inner layer 3 that is an iron-based material, so if the bonding temperature is less than 1000 ° C., the surface between the outer layer 2 and the inner layer 3 This is because sufficient pressure may not be obtained due to insufficient pressure, and when the bonding temperature exceeds 1320 ° C., the outer layer 2 made of cemented carbide may melt during bonding. A more preferable joining temperature is 1100 to 1300 ° C, and a further preferred joining temperature is 1200 to 1260 ° C.

The fitting between the outer layer 2 and the inner layer 3 is set in consideration of the thermal expansion coefficient and deformability of these members so that there is no gap between the members and the members are in close contact when heated to the joining temperature. If necessary, a restraining member 14 that restrains the thermal expansion of the inner layer by having a thermal expansion coefficient smaller than that of the inner layer 3 is disposed outside the outer layer 2. By disposing such a restraining member 14, diffusion bonding between the outer layer 2 and the inner layer 3 can be performed reliably. The restraining member 14 may be any material that has a smaller coefficient of thermal expansion than the outer layer 2 and the inner layer 3, has a certain strength at the joining temperature, and is difficult to plastically deform.For example, graphite, alumina, etc. can be used. Graphite is preferred because of its ease.

The cemented carbide composite sleeve roll 1 is manufactured by machining the rolled forming portion 2a and the like into a groove shape in a part of the outer peripheral surface of the outer layer 2 of the obtained composite sleeve roll body 9 made of cemented carbide. Here, FIG. 2 is a schematic sectional view showing an example in which the cemented carbide composite sleeve roll of the present invention is assembled to a shaft member. In FIG. 2, a fixing ring 7 is fitted and fixed to the outer periphery of the shaft member 6 provided with the flange portion 6a on one side so as to be in contact with the flange portion 6a. Next, a cemented carbide composite sleeve roll 1 is fitted to the outer periphery of the shaft member 6. Next, the cemented carbide composite sleeve roll 1 is fixed by inserting a fastening ring 8 for fixing on the outer periphery of the shaft member 6 and screw fastening, and the cemented carbide assembly roll 10 is assembled in a detachable manner. To fit the composite sleeve roll 1 made of cemented carbide on the outer periphery of the shaft 6, a key groove is provided on the inner peripheral surface of the inner layer 3 and the outer peripheral surface of the shaft 6 and fixed with a key. Also good.

[HIP method]
FIG. 4 is a schematic cross-sectional view for explaining a method when the cemented carbide composite sleeve roll of the present invention is manufactured by the HIP method. In FIG. 4, a hollow cylindrical inner layer 3 is arranged in the center of a cylindrical HIP can 15. In the gap formed between the outer surface of the inner layer 3 and the inner surface of the HIP can 15, a sleeve made of a cemented carbide sintered body or a temporary sintered body is disposed as the outer layer 2. The HIP can is hermetically sealed with a steel lid, deaerated with a vacuum pump, and then HIPed with a HIP device. The HIP treatment temperature is preferably 1100 to 1300 ° C. and the pressure is preferably 100 to 140 MPa. After cooling, the HIP can is removed by machining to obtain a cemented carbide composite sleeve roll body 9 in which the outer layer 2 made of cemented carbide is joined to the outer periphery of the inner layer 3. The outer layer can also be formed by filling the gap between the inner layer 3 and the inner surface of the HIP can 15 with cemented carbide powder.

In the same manner as described above, the composite sleeve roll 1 made of cemented carbide is manufactured by machining the rolled forming part 2a and the like into a groove shape on a part of the outer peripheral surface of the outer layer 2 of the obtained composite sleeve roll body 9 made of cemented carbide To do.

EXAMPLES Hereinafter, although it demonstrates in detail based on the Example of this invention, this invention is not limited to these Examples.

Example 1
A cylindrical outer layer material test piece 31 made of a cemented carbide having the characteristics shown in Table 1 and having an outer diameter of 20 mm and a thickness of 20 mm was prepared. On the other hand, five types (inner layers 1 to 5) of cylindrical inner layer material test pieces 32 made of an iron-based material having the composition shown in Table 2 and having an outer diameter of 30 mm and a length of 25 mm were prepared. The outer layer material test piece 31 and the inner layer material test piece 32 are stacked as shown in FIG. 5 and stored in a graphite jig 34, and then the pressure is applied to the stacked surface in a vacuum in Table 2. Bonding was performed under the conditions shown, and bonding test pieces 35 of Test Nos. 1 to 5 were produced. Thereafter, the bonding boundary of the obtained bonding test piece 35 was observed.

In the test specimens of Test No. 1 and Test No. 4, since the generation of η phase and graphite was suppressed at the joint boundary between the inner layer material test piece 32 and the outer layer material test piece 31, the joint strength was sufficiently high and the joint reliability Is expensive. In the joining test piece of Test No. 3, since the graphite was generated at the joining boundary between the inner layer material test piece 32 and the outer layer material test piece 31, it is assumed that the joining strength is low. Further, in the joining test pieces of Test No. 2 and Test No. 5, since the η phase was confirmed at the joining boundary between the inner layer material test piece 32 and the outer layer material test piece 31, it is assumed that the joining strength is low.

(Example 2)
Two types of test pieces of φ25 mm × 75 mm were prepared using the test piece of φ25 mm × 75 mm having the characteristics shown in Table 1 as the outer layer material and the inner layer 1 shown in Table 2 as the inner layer material. The outer layer material test piece 41 and the inner layer material test piece 42 were stored in a graphite jig, and the pressure was applied to the stacked surfaces in the same manner as shown in FIG. Joining was performed under the conditions shown to produce test specimens 45 of Test Nos. 6 and 7. A tensile test piece 46 as shown in FIG. 6 was produced from the obtained joint test piece 45. The tensile test piece 46 had a diameter of 6.3 mm and a gauge distance of 19 mm, and a boundary junction was present in the center between the gauge marks. Using the obtained tensile test piece 46, a tensile strength test and a fatigue strength (pulling pressure) test were performed.

The test results are shown in Table 3. In the tensile test piece 46 of test No. 6, both the tensile strength and the fatigue strength were higher than the tensile test piece 46 of test No. 7, the tensile strength was 600 MPa or more, and the fatigue strength was 200 MPa. .

(Example 3)
A hollow cylindrical outer layer 2 having the characteristics shown in Table 1 and having an outer diameter of 360 mm, an inner diameter of 313 mm, and a total length of 280 mm was prepared. Further, an inner layer 3 made of an iron-based alloy (inner layer 6) having the composition shown in Table 4 and having an outer diameter of 312 mm, an inner diameter of 245 mm, and an overall length of 320 mm was prepared. Further, a constraining member 14 made of graphite having a hollow cylindrical shape having an outer diameter of 600 mm, an inner diameter of 361.7 mm, and an overall length of 350 mm was prepared. As shown in FIG. 3, the outer layer 2 is disposed on the outer peripheral side of the cylindrical inner layer 3 disposed on the base 11 made of graphite, and each member is formed of hollow cylindrical graphite on the outer peripheral side of the outer layer 2. A restraining member 14 was arranged. With these members arranged as shown in FIG. 3, they were placed in a vacuum furnace and joined at a temperature of 1250 ° C. to produce a hard sleeve composite sleeve roll body 9 of Test No. 8. A cemented carbide composite sleeve roll 1 is obtained by machining a groove-shaped rolled forming portion 2a as shown in FIG. 1 on a part of the outer peripheral surface of the outer layer 2 of the obtained cemented carbide composite sleeve roll body 9. Was made.

After the bonding treatment, visual inspection of the outer layer and inner layer ends and penetration inspection of the entire bonded surface were performed. As a result, no boundary defect was observed over the entire bonding surface. Further, no peeling of the outer layer and the inner layer was observed.

1 Cemented carbide composite sleeve roll, 2 Outer layer, 2a Roll forming part, 3 Inner layer,
3a Inner surface of inner layer, 4 boundary part, 5 hollow part, 6 shaft material, 6a flange part,
7 fixing ring, 8 fastening ring, 9 cemented carbide composite sleeve roll body,
10 Cemented carbide assembly roll,
11 base, 12 cradle, 14 restraint member, 15 HIP can,
31, 41 Outer layer specimen, 32, 42 Inner layer specimen,
34 Graphite jig, 35, 45 Joined specimen, 46 Tensile specimen

Claims (5)

In a cemented carbide composite sleeve roll in which an outer layer made of cemented carbide having a rolled formed part formed on the outer circumferential surface is metal-bonded to the outer circumference of a hollow inner layer made of an iron-based material, the inner layer has a C content of 0.75 to 1.2 mass. Ni, 1.9 to 7.5% by mass, Cr 0.01 to 3% by mass, Mo 0.01 to 1.5% by mass, Si 0.5 to 2% by mass, Mn 0.1 to 0.9% by mass , balance iron and inevitable impurities Cemented carbide composite sleeve roll characterized by The composite sleeve roll made of cemented carbide according to claim 1 , wherein the tensile strength at the boundary between the outer layer and the inner layer is 600 MPa or more. 3. The cemented carbide composite sleeve roll according to claim 1, wherein a fatigue strength of a boundary portion between the outer layer and the inner layer is 200 MPa or more. The composite sleeve roll made of cemented carbide according to any one of claims 1 to 3 , wherein the outer layer made of the cemented carbide contains 70 to 88% by mass of WC. A cemented carbide composite sleeve roll according to any one of claims 1 to 4 , wherein the cemented carbide composite sleeve roll according to any one of claims 1 to 4 is detachably assembled to an outer periphery of a roll shaft member.