JPS6018485B2 - Composite cemented carbide hot rolling roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot rolling roll made of a composite cemented carbide made of cemented carbide and steel or cast iron.

Conventionally, cemented carbide represented by WC-Co, WC-TIC-Co, etc. has been widely used for cutting tools, wear-resistant parts, impact-resistant tools, etc., but it is especially used as wear-resistant parts for hot rolling rolls and wires. In drawing dies, etc., the rutting resistance of cemented carbide is lower than that of steel, so if solid carbide is used, the dimensions are made larger than necessary to increase the safety factor.

However, cemented carbide contains WC and TIC as the main components.
, TaC is expensive, making the product extremely expensive, and there are also problems in terms of resource conservation. To solve this problem, cemented carbide is usually used only in parts that require wear resistance, and is used as a composite part with steel or cast iron.

To manufacture this composite member, a casting is joined to the inner surface of a cemented carbide ring by coin casting, and a steel ring is joined to the inside using cold iron casting, or a cemented carbide and steel member is manufactured. Put a brazing material such as Ag in between and make the whole 600~900
There is one in which both are brazed together by heating with oo. However, with the former method, the workability of casting coins is poor (the processing method is inferior), and the strength of the joint surface is insufficient. In addition, since the latter is manufactured by heating the entire body at high temperatures, the coefficient of thermal expansion of cemented carbide is approximately 1/2 that of steel, so thermal stress remains on the brazed surface and may cause it to crack during use. There were some problems, such as difficulty. The problem of thermal stress is similar in the former case. In addition, in the brazing method, the brazed layer has poor fatigue strength at high temperatures and is subject to phenomena such as brazing coming off during use, resulting in poor heat resistance. The present invention is to provide a composite super-iso alloy for use in hot rolling rolls, in particular, as a bonded wear-resistant member that does not generate thermal stress and has high heat resistance, as described above, by improving the joining method of cemented carbide and steel materials. This makes it possible to manufacture large parts that were previously impossible.

As a result of extensive research, the present inventors have found that when joining steel materials and hard alloys, complete joining is possible by melting the joint surfaces in one or two fences, and it is possible to achieve complete joining without providing an intermediate layer on the joint surfaces. It has been found that composite members made by this method have superior performance compared to conventional ones.

In addition, as a method of dissolving the joint surface in one or two legs,
There are various methods such as arc welding and TIC welding, but if high energy beams such as electron beams and laser beams are used, the steel side of the bale surface will be melted tipwise due to thermal conductivity, and the cemented carbide It was discovered that the side surface of the bale hardly dissolves.

The use of electron beams as a method for joining metals is already known, as seen in Hakamakai No. 56-45288, etc., but as described above, It is characterized by the fact that it is carried out by irradiating electron beams to melt the joints, or by melting and joining both abutting surfaces.

However, in the case of cemented carbide and steel, even if the electron beam is irradiated only on the contact surface on the cemented carbide side, the melting will be incomplete, and if the electron beam is irradiated only on the contact surface on the steel material side, the melting will be wider. Since there is no heating on the hard metal side, the joint strength is significantly reduced.

In the present invention, it is necessary to irradiate a high-energy beam such as an electron beam so that it hits both the contact surfaces of the cemented carbide and the steel material, thereby creating a heating effect on the cemented carbide side and moderate melting on the steel material side. High-strength bonding is possible only when the inside is obtained. Therefore, it is also important that the surface of the bale to be irradiated be irradiated by heating, cold ironing, pressurizing, etc. so that it is brought into sufficient contact with the bale surface. Since the composite hot rolling roll according to the present invention does not raise the entire body to a high temperature, no stress is generated due to the difference in coefficient of thermal expansion, so there is no deformation or cracking during use, and there is no need to heat the composite hot rolling roll to a high temperature. Since it is a direct bond, the fatigue strength is high and the compression strength is also high.

Another feature is that the melted layer occurs only in the steel material, and the cemented carbide is not completely melted, so no verticalized layer Fe8W3C is generated due to the reaction between the cemented carbide and the steel Fe. Next, embodiments of the present invention will be described. When the cemented carbide and the steel material are relatively small, that is, the joining surface is 4 mm, the steel material side is melted in the 1st or 2nd side over the entire surface of the supporting surface as shown in Fig. 1. In the case of large wear-resistant parts such as hot rolling rolls (Morgan rolls, etc.), it has been found through various experiments that it is sufficient to melt the melt to a depth of 2 m or less of the joint end surface. In normal cases, welding surfaces on the 5th to 15th sides are sufficient. FIG. 2 is a sectional view showing an embodiment of a hot rolling roll, in which a steel ring 6 such as SCM 21 is iron-bonded to the inside of a cemented carbide ring 5 by cold ironing, and the end of the rear surface A of both is iron-bonded. The super-alloy ring 5 and the steel ring 6 are joined by irradiating an electron beam 3 on the steel ring 5 to form a molten layer 7 on the steel bale side surface. In this way, the center part, where the stress is most applied, is a direct bond between the cemented carbide and the steel material, and there is no worry of the bonding layer causing snapping, and the fatigue strength as a whole is increased. In addition, as for the steel parts to be joined, the joint surface with the cemented carbide is better in terms of adhesion and strain absorption, and it is desirable to use steel with a carbon content of 0.5% by weight or less. Increasing the hardness and wear resistance by carburizing and quenching gave preferable results in the case of rolling rolls and the like.

This is because the welding surface can be prevented from increasing hardness and forming arms due to rapid cooling, while when used as a tool, wear resistance is required and the HRc can be maintained at about 50 to 60.

Next, when the joint surface is irradiated with a high-energy beam to partially melt the supporting surface, the steel material may melt and the carbon and oxygen in the steel material may react and generate gas. It is effective to provide degassing grooves when processing the steel parts in advance, and it is possible to remove blowholes in the bonding layer.

Figure 3 is an external view of the steel member in the case of the above-mentioned rolling roll, and a partially enlarged sectional view of the steel member, where 8 is the groove located at the tip of the welding beam, and 9 and 9' are inside the bonded molten layer. This is a gas vent groove for discharging gas generated from the gas to the outside. The present invention is also effective when a cemented carbide member and a plurality of steel members are combined.

The melted and fixed depth of 5 ~ at both ends in the thickness direction of the mating surface
It is undesirable to have two capes because if the number is less than five, the joint strength will be weak, and if the number exceeds two, the energy beam will become thicker at the end of the joint surface. In addition, the amount of bound metal is 1
If it is less than 45% by weight, the strength of the cemented carbide is insufficient;
If it exceeds this, the wear resistance will decrease. The carbon content of steel members is 0.
If the content is less than 0.01% by weight, the strength of the steel will be insufficient, and if it exceeds 0.5% by weight, competitive cracking will occur during welding. Also,
The coefficient of thermal expansion is 4 x lower than that of cemented carbide, which means that the coefficient of thermal expansion is 4 x lower than that of 3 x lo-6, and the difference between the outer steel ring and the outer steel ring is large, and a large stress is generated between the outer ring and the inner ring. occur between Furthermore, when the coefficient of thermal expansion becomes larger than 10 x 10-6, large stress occurs at the interface between the cemented carbide and the steel inner ring, causing the joint to separate or cracking in the cemented carbide ring.The elastic modulus is 50 kg. If the welding stress exceeds that point, welding stress will be applied to the carbide ring, causing cracks in the carbide ring. If pure Ni or pure Co fillers are used, bondability will be further improved and stress relaxation will be effective. In the case of rolling rolls and slitters, a composite member is often required in which a different type of steel ring or cast iron ring is interposed between a cemented carbide ring and a steel ring. One of them is that the inside of the cemented carbide ring has a thermal expansion coefficient of 3 to 10 x 10-300℃.
6 skin/℃ Iron-nickel alloy materials are joined, and a steel ring with higher wear resistance than the steel ring is joined inside the iron-nickel alloy ring. In this case, a cast iron ring that is relatively soft and has an elastic limit of 50k9/Iso or less that can absorb thermal expansion is joined to the inside, and a steel ring is joined to the inside of the cast iron, but in either case, the cemented carbide part As a result of applying the above-described method of the present invention to the joining of steel rings or cast iron rings to be joined at the center and the middle, a product having a longer life than a three-layer composite roll or slitter produced by the conventional method was obtained. The material having the above-mentioned specific coefficient of thermal expansion may be Ni, Co, Fe--Ni alloy, Kovar, or the like. This is particularly useful under conditions of use that are susceptible to heat. The high-energy beam irradiated to the twill surface is preferably an electron beam or a laser beam in terms of joining accuracy, and a non-oxidizing atmosphere or vacuum is required to prevent oxidation of steel materials and cemented carbide, especially for degassing. From this point of view, it is preferable to use a vacuum.

Example 1 Willow with an outer diameter of 159 mm and an inner diameter of 87 mm? In a Morgan roll with a thickness of 7 mm as shown in Fig. 2, the cemented carbide part was processed to have an outer diameter of 159 ribs and an inner diameter of 123 ribs, and the steel material SC
M21 was machined to have an outer diameter of 123 mm and an inner diameter of 87 mm.

Only the outer circumferential surface of this steel ring is protected from charring, and the inner periphery and upper and lower surfaces are quenched, and the steel surface is HRc.
It was set at 55. In addition, the steel ring is heated in the third stage before being quenched with horse mackerel charcoal.
As shown in the figure, grooves and gas vent grooves were provided. Next, the cemented carbide ring and the charcoal-quenched steel ring were bonded together with zero side joining distance.
．． The 015 side was cooled and iron plated, and both were brought into close contact with the bale.
An electron beam is applied to the circumference of the end surface of this bale surface A at a voltage of 6 plates V.
The beam was irradiated under the conditions of a current of 90 A, a speed of 800 sides/min, and a vacuum so that the beam hit the cemented carbide side and the supporting surface of the steel side. A weld layer with a depth of 15 ribs on the 1.0 to 1.5 side was observed on the steel side of the roll obtained, and the supporting surface on the hard metal side did not melt at all and the two were completely joined. Ta. Next, the ring strength of this roll was measured and found to be 51.3 tons. Note that the radial crushing strength of a composite roll of the same size manufactured by the conventional brazing method was 27 tons, which was about twice the strength. As described above, according to the present invention, a wear-resistant member with strong adhesion strength and no stress after joining can be manufactured with high precision and at low cost. Example 2 In a Morgan roll having the same dimensions as Example 1, the cemented carbide part (FIG. 4) was machined to have an outer diameter of 159 and an inner diameter of 126, and a steel material SCM445 with an outer diameter of 126 and an inner diameter of 87.
The steel ring 12 was machined to have a hardness HRc44 by quenching.

Ni rings 13 (outer diameter 126 side × inner diameter 106 sides, thickness 1 inch) are placed on the upper and lower outer peripheries of the steel ring as shown in Fig. 4.
It was ironclad. The supporting surface B was ground so that the iron alloy thickness was 0.03, and the carbide ring and the steel ring were integrated by cold cutting. The electron beam was applied at a voltage of 15 V, a current of 1 hA, and a speed of 500 m/m so that only the Ni portion of support surface B was welded.
In, irradiation was carried out under vacuum at 104 Ton. In FIG. 4, a portion 14 was welded to join the cemented carbide and the Ni ring, and a portion 15 was welded to join the Ni ring and the steel ring. This composite roll was then finished to a predetermined size. When this roll was used as a wire rod rolling roll under rolling conditions of a bran material temperature of 900 qo and a linear speed of 60/sec, it exhibited a life of 500 Ton/KAL, which was exactly the same performance as a conventional solid cemented carbide roll. Furthermore, it was found that the roll could be used many times after recutting, and could be used up to a cemented carbide thickness of 5, and its fracture resistance was superior to that of a solid carbide roll. Example 3 Similar to Example 2, a carbide ring and a steel ring were prepared, and the Fe-Nj40 ring had an outer diameter of 12 mm on the outer periphery of the steel ring.
It was made of 6 willows, with an inner diameter of 106 ribs and a width of 7 ribs.

The three layers of the carbide ring, Fe-40Ni ring, and steel ring were assembled as shown in FIG. 5, and after welding the section 18 in the figure with an electron beam, the section 19 was welded. No sharpness caused by welding was observed at all. Examples 1 and 2 when this roll was used as a hot rolling roll.
Similarly, it had a long life and better cracking resistance than solid carbide rolls. Example 4 A carbide ring and a steel ring were prepared in the same manner as in Example 3, and a Fe-40Ni ring having a small coefficient of thermal expansion was placed around the outer periphery of the steel ring.

Is the ring of the Fe-4 state i an outer diameter of 126mm? , inner diameter 106
Side facing, width 70 side. The carbide ring, the Fe-40Nj ring, and the steel ring were assembled in three layers as shown in FIG. 5, and after welding the section 18 in the figure with a laser beam, the section 19 was welded.

No sharpness caused by welding was observed at all.

When this roll was used as a hot rolling roll, it had a long life comparable to that of Examples 1 and 2, and had better cracking inertia than the solid carbide roll.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a composite member of a cemented carbide cylinder and a steel cylinder to explain the principle of the present invention, Fig. 2 is a sectional view of a composite roll showing one of the embodiments of the invention, and Fig. 3 is a sectional view of a composite member of a cemented carbide cylinder and a steel cylinder. 2 is an external view of the steel ring in the embodiment of the present invention of the same machine and a partial cross-sectional view thereof; FIG. 4 and 5 are cross-sectional views of hot rolling rolls of other embodiments. 1, 5, 11, 15... Cemented carbide club village,
2, 6, 6', 12, 16... Steel member, 3.
...High energy beam, 4,7...Welding surface, 8,8',9,9'...Groove, 10...
・Welding interface, A, B, C... Back surface, 13...Ni
Ring, 14, 15, 1 8, 1 9... Welded part, 17... Fe-40M ring. Bar figure Juice 2 figure Juice 3 figure Bar 4 figure Power 5 figure

Claims (1)

[Claims] 1. A steel ring is brought into contact with the inside of a cemented carbide ring, and the contact surfaces of the steel ring of 5 mm or more and 20 mm or less at both ends in the thickness direction of the surface are slit-shaped by a high-energy beam. 1. A hot rolling roll made of a composite cemented carbide, characterized in that it is melt-solidified and the surface that contacts the cemented carbide is melted and fixed. 2 The cemented carbide has WC as its main component and the amount of combined metal is 10% by weight or more and 45% by weight or less, and the steel member that comes into contact with the cemented carbide has a carbon content of 0.01% by weight or more and 0.5% by weight or less. Claim 1, characterized in that the parts other than the contact surface are carburized and quenched to impart high hardness and wear resistance.
A hot rolling roll made of a composite cemented carbide as described in 2. 3 The inside of the cemented carbide ring has a thermal expansion coefficient of 3~10x up to 300℃.
An iron-nickel alloy ring with a temperature of 10^-^6cm/°C, a cast iron ring with an elastic limit of 50kg/mm^2 or less, or pure metals such as Ni and Co are brought into direct contact with the inside of the steel ring or cast iron ring. A highly wear-resistant steel ring is in direct contact with the steel ring, and part or all of the steel side of the contact surface between the cemented carbide and the outer steel ring is melted and solidified using a high-energy beam to form a slit. A hot rolling roll made of composite cemented carbide, characterized in that the contact surfaces of the outer and inner rings are also welded by high-energy beams. 4. The composite cemented carbide hot rolling roll according to claim 1 or 3, wherein the high-energy beam is an electron beam or a laser beam.