JPH08267192A - Mold roll for twin roll type strip continuous casting and production thereof - Google Patents

Abstract

PURPOSE: To provide a mold roll for twin roll type strip continuous casting, in which the welded parts in a roll producing section can be reduced and the repair at the job site can easily be executed, and a producing method of the mold roll for twin roll type strip continuous casting, in which the melting depth can be uniformized and the necessary toughness is secured without executing heat treatment for removing the stress. CONSTITUTION: After fixing a roll base material 20 and a roll shaft part 10 separately produced, an erosion resistant alloy 28 is formed on the roll surface of the roll body part 20 with a build-up welding. End part members 30 are fixed and roll body side plates 40 are fixed freely attachably/detachably to the end parts of the roll body part 20 with the welding. Communicating passages 48, 49, water supplying passage 31 and water draining passage 35 are formed while reducing the welding positions at both end parts of the roll, and a baffle plate 45 is arranged in the communicating passage 48.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thin steel plate having a thickness of 2 mm to 6 mm directly cast from a molten metal and subjected to direct cold rolling without a hot rolling process to form a thin steel plate having a thickness of about 0.3 mm to 0.5 mm. The present invention relates to a mold roll for twin-roll thin plate continuous casting used for manufacturing, and a method for manufacturing the mold roll.

[0002]

2. Description of the Related Art For example, a thin steel plate having a thickness of about 0.3 mm to 0.5 mm is usually processed by a slab continuous casting machine from a slab material having a thickness of 100 mm to 150 mm through hot rolling and cold rolling. Manufactured. According to this method, not only the number of steps is large, but also the once cooled slab material needs to be heated again for hot rolling. for that reason,
A twin roll type thin plate continuous casting machine, which directly casts steel plates from the molten metal, is used.

The thickness of the slab cast by the conventional twin roll type thin plate continuous casting machine is as thin as 2 to 6 mm, and if the slab is cooled unevenly, it may cause cracking of the slab. In order to solve this, conventionally, for example, mold rolls found in Japanese Patent Laid-Open Nos. 3-210944 and 4-118250 have been provided.

That is, in the former mold roll disclosed in Japanese Patent Laid-Open No. 3-210944, a ridge is formed on the inner peripheral surface of a roll cylinder which is externally fitted and fixed to the roll main body, and the ridges are formed from the center to both ends. A continuous spiral cooling groove is provided, a cooling water supply passage communicating with the inner end of the cooling groove is provided at the center of the roll body, and both ends of the roll body are provided at the outer end of the cooling groove. A cooling water drainage channel communicating with each other is provided, and each ridge of the roll cylinder is fixed to the outer periphery of the roll body. And fixing the roll body and the roll cylinder,
The fixing of the roll main body and the end support plate, the fixing of the end support plate and the roll core, and the fixing of the water supply pipe and the drain pipe are all performed by welding.

The latter mold roll, which is disclosed in Japanese Utility Model Laid-Open No. 4-118250, has a plurality of cooling water passages along the axial direction formed in the roll body at predetermined intervals in the circumferential direction. The heat transfer surface on the front surface side is formed in a cross-sectional shape substantially parallel to the roll surface. And fixing of each part,
Like the former, everything is done by welding.

Further, conventionally, the mold roll used in the twin roll type thin plate continuous casting machine uses the base metal of the roll base material made of copper or copper alloy having good thermal conductivity and the iron base alloy having high strength. It is roughly divided when using.

Of these, when copper or a copper alloy is used for the roll base material, it is intended to prevent the surface of the roll having a low wear strength from being worn, and because the roll base material has a high thermal conductivity. Since the cooling rate during the initial solidification is higher than necessary and solidification may occur in a structure other than the target metal structure, the cooling rate must be adjusted. Then, in order to adjust the cooling rate, nickel or nickel-chromium alloy (Ni-Cr alloy) is coated on the roll surface. The coating method is generally plating. When an iron-based alloy is used as the base metal, the coating for adjusting the thermal conductivity of the roll surface is not required because the base metal has a low thermal conductivity.

[0008]

With the conventional configuration described above,
The mold rolls found in Japanese Unexamined Patent Publication No. 3-210944 and Japanese Unexamined Utility Model Publication No. 4-118250 have been improved in that the slab is cooled uniformly, but in both types, all parts are fixed by welding. That is, since there are many welded parts in the roll manufacturing part, there is a problem that the manufacturing time and cost increase.

When copper or a copper alloy is used as the roll base material, nickel or nickel-chromium alloy is plated and coated on the surface of the roll, but since thermal stress is not applied during coating, stress is not applied after plating and coating. It has the advantage of not requiring a heat treatment for removal, but repairs to remove wear or any scratches during use and restore it to a usable state are either impossible in the field, or are extremely necessary during the repair plating process. It takes a long time.

Further, when copper or a copper alloy is used as the roll base material, it is difficult to build up the weld. Therefore, in order to enable welding, steel plates are explosion-bonded or diffusion-bonded to the roll base material, and This explosion-bonded or diffusion-bonded steel plate must be coated with nickel or nickel-chromium alloy. When coating in this way, weld overlay is possible, but the thickness of the steel plate must be large enough to guarantee the depth of penetration during welding, so the effect of good heat conduction of the roll base material is achieved. Or the need for copper or copper alloy as the roll base material is eliminated.

On the other hand, when an iron-based alloy is used as the base metal, a coating for adjusting the thermal conductivity of the roll surface is not required because the base metal has a low thermal conductivity, but high temperature oxidation resistance is not required. Excellent materials are expensive and roll costs are high.If a material that does not have high temperature oxidation resistance is used for the roll base material, the surface should be resistant to high temperature oxidation such as stainless steel to prevent high temperature oxidation. Must be protected with good material. As the coating method, since a weld overlay is possible, a weld overlay method, which is a simple processing method, is used.

This welding build-up method has the advantages that the construction period is short and that cutting removal, additional build-up, and repair build-up are easy at the site of use, but on the other hand, it is based on welding. The penetration depth changes depending on the welding conditions (the penetration depth varies), and it is difficult to achieve a constant penetration depth. Variations in the penetration depth cause uneven cooling of the slab and cause cracks in the slab. In addition, since the iron-based alloy base material hardens due to the heat applied during welding overlay, it is necessary to perform heat treatment for stress relief after welding overlay to secure the required toughness, etc. Has the drawback of.

In the case of performing stress relief heat treatment, no matter how much heat treatment is performed only on the welded portion, it takes some time for the temperature to rise, and the internal temperature of the roll base material rises during this time. It is not possible to adopt a roll structure which is disadvantageous when the temperature rises. That is, the mold roll is a part of the roll surface (sleeve) that is in contact with the molten metal,
It is composed of the shaft part that rotates the mold roll,
It is most economical to use a shrink fit structure for the connection between the shaft and the sleeve part, but this structure is used because the welding heat treatment far exceeding the shrink fit temperature is performed immediately before the final processing. Was impossible. It is possible to build up the sleeve body before shrink-fitting and shrink-fit it to the shaft after heat treatment, but keep the sleeve shape sound as it causes thermal deformation during heat treatment. Is not realistic.

The object of the present invention is to reduce the number of welded parts in the roll manufacturing part and to easily perform on-site repairs. A twin roll type thin plate continuous casting mold roll and a uniform penetration depth. Another object of the present invention is to provide a method for producing a mold roll for twin-roll type thin plate continuous casting that can obtain the required toughness without performing heat treatment for stress relief.

[0015]

In order to achieve the above object, the first aspect of the present invention supplies molten metal to a space formed by a pair of rolls facing each other and rotates in a direction sandwiching the rolls facing each other. In a mold roll used in a twin roll type thin plate continuous casting machine for producing a thin plate from a molten metal by pressure bonding a metal solidification layer generated on the roll surface,
Inside the vicinity of the roll surface, a plurality of cooling water channels along the roll axis direction are formed at predetermined intervals in the circumferential direction, and the ends of the cooling water channel group communicate with the roll shaft side water channels at the ends of the roll body. The cooling water distribution path is formed, and the baffle located in the cooling water distribution path is provided.

Further, according to the second aspect of the present invention, while supplying the molten metal to the space formed by a pair of rolls facing each other, the metal solidified layer formed on the roll surface by rotating in the direction in which the rolls facing each other are rotated. In a mold roll used in a twin roll type thin plate continuous casting machine for producing a thin plate from molten metal by pressure bonding, a cylindrical roll base material is externally fitted and fixed to a roll shaft, and this roll base material is a roll surface. While forming a corrosion-resistant alloy by overlay, in the vicinity of the roll surface, a plurality of cooling water channels along the roll axial direction are formed at predetermined intervals in the circumferential direction, and end members are provided at both ends of the roll base material. By fixing, between the end surface of the roll base material and the inner surface of the end member, a water supply channel or a drain channel communicating with the cooling water channel group is formed, and the roll main body side plate extends between the end member and the roll shaft. Detachable It is provided with a baffle plate positioned communication passages communicating with the water supply passage or drain passage and the roll axis side waterways.

The third aspect of the present invention is the mold roll for twin-roll type thin plate continuous casting according to the first or second aspect of the present invention, wherein two locations are provided in the cooling water distribution path from the roll axis side water passage to the cooling water passage group. The above baffles are provided.

Further, in the fourth invention, in the mold roll for twin-roll type thin plate continuous casting according to the above-mentioned second invention, the roll shaft and the roll base material are made of ordinary carbon steel or low alloy steel, and the roll shaft is manufactured. A cylindrical roll base material is externally fitted and fixed by shrink fitting, and a groove is provided at the end of the shrink fitting portion.

Further, in the fifth invention, in the twin roll type thin plate continuous casting mold roll according to the first or second invention, the inside of the cooling water channel group is plated. In order to achieve the above object, the sixth aspect of the present invention is to solidify a metal generated on a roll surface by supplying molten metal to a space formed by a pair of rolls facing each other and rotating the rolls facing each other in a direction in which the rolls face each other. In a manufacturing method of a twin roll type thin plate continuous casting mold roll for manufacturing a thin plate from a molten metal by crimping a layer, after externally fitting and fixing a cylindrical roll base material to a roll shaft by shrink fitting, the roll A corrosion resistant alloy is formed on the surface of a base material by overlaying, and the overlayed corrosion resistant alloy is processed.

The seventh invention is the method for producing a mold roll for twin roll type thin plate continuous casting according to the sixth invention, wherein a low alloy steel is used as a roll base material and a corrosion resistant alloy is used on the surface thereof. It is formed by a weld overlay of multiple layers of more than one layer.

The eighth aspect of the present invention is the method for producing a mold roll for twin-roll type thin plate continuous casting according to the seventh aspect, wherein the iron component of the overlay material is more than the target component during the welding overlay of the first layer. In addition, the weld overlay is performed with a predetermined component material when overlaying the second layer or more.

The ninth aspect of the present invention is the method for producing a mold roll for twin-roll type thin plate continuous casting according to the seventh aspect, wherein the welding overlay of the first layer is a reverse polarity soft plasma overlay method or similar. The small heat input welding overlay method of
Then, the welding overlay of the second layer or more is performed by the powder plasma overlay method or the high heat input welding overlay method, and at the same time, the welding tempering is performed by the powder plasma overlay or the high heat input welding overlay. .

[0023]

According to the structure of the first aspect of the present invention described above, when the cooling water flows from the roll shaft side water passage to the cooling water distribution passage, the cooling water can be diffused and mixed by the baffle plate to be uniformized, and the cooling water can be evenly distributed in each cooling water passage. Can be supplied.

According to the structure of the second aspect of the present invention, the separately manufactured roll shaft and the roll base material are externally fitted and fixed, and then the corrosion resistant alloy is formed on the roll surface of the roll base material by overlaying, , The roll body side plate is detachably fixed.
Thereby, the communication passage, the water supply passage, and the drainage passage can be formed at both ends of the roll with a reduced number of welding points, and the baffle plate can be arranged in the communication passage.

According to the structure of the third aspect of the present invention, when the cooling water flows through the cooling water distribution path, the cooling water can be diffused and mixed by the baffle plates at a plurality of positions so as to be uniform, and can be evenly supplied to each cooling water passage. .

Further, according to the structure of the fourth aspect of the present invention, by integrating the roll shaft and the roll base material by shrink fitting,
The cost can be reduced, and the roll base material that has finished the hole drilling of the cooling water channel can be easily mounted on the long roll shaft. Also, due to the groove, excessive heat deformation stress is concentrated on the shrink fit part when the roll is used. Therefore, it is possible to prevent the roll core material from being damaged due to an excessive stress applied to the roll shaft core portion due to the thermal deformation of the roll base material.

Moreover, according to the structure of the fifth aspect of the present invention, it is possible to prevent the inner surface of the cooling water passage from being oxidized by the plating treatment, and to easily perform on-site repair. According to the configuration of the sixth invention described above, a mold roll having abrasion resistance and low thermal conductivity can be easily obtained at low cost, and can be used by removing abrasion or any scratch during use. Repairs to return to the state can be performed easily and quickly on site.

According to the structure of the seventh aspect of the present invention, the low alloy steel is formed by a multi-layered structure having two or more layers, whereby the roll base material is welded and tempered to recover the toughness of the roll base material. With this, the weld surfacing can be performed on the roll surface without the stress relief heat treatment of the weld surfacing.

According to the structure of the eighth aspect of the invention, the phenomenon of component dilution in the build-up layer, which occurs due to the difference between the base material component and the build-up component, is utilized, that is, the main component of the roll base material, iron, is diluted. In the case of overlaying the first layer, iron is removed from the components of the weld overlay material or reduced to below the specified component to become a predetermined component during overlay welding, and when overlaying the second layer or more, By using the welding material of the build-up component, the whole build-up layer becomes a predetermined component target.

Furthermore, according to the ninth aspect of the present invention, the weld overlay of the first layer can be carried out while preventing deep penetration, and the penetration depth can be made uniform so that the physical properties of the mold roll surface can be made uniform. And, the weld overlay of the second layer and above is
A roll base material made of an iron-based alloy by shortening the welding build-up time and making the weld build-up defect less prone to perform deep penetration, and at the same time, by utilizing the welding tempering by the high heat input welding build-up. It is possible to recover the toughness of the portion, and thus it is possible to perform the weld overlay on the roll surface that does not require the stress relief heat treatment after the completion of the weld overlay.

[0031]

An embodiment of the present invention will be described below with reference to the drawings. The body of the mold roll 9 comprises a roll shaft 10 and a roll base material 20 made of ordinary carbon steel or low alloy steel.
And a corrosion resistant alloy 28. Here, the mold roll 9 is used in a twin roll type thin plate continuous casting machine. That is, while supplying the molten metal to the space formed by the pair of mold rolls 9 facing each other, by rotating the mold rolls 9 facing each other in a direction in which the mold rolls 9 are sandwiched, the metal coagulation layer generated on the roll surface is pressure-bonded. It is used in a twin-roll type thin plate continuous casting machine for producing thin plates from molten metal.

The roll shaft 10 comprises a shaft main body 11 and a shaft support 12 extending outward from both ends of the shaft main body 11, and both shaft support 12 are supported by the bearing device 1. A cooling water supply passage 13 and a cooling water discharge passage 16 are formed in one of the shaft support portions 12 and in the other on the roll shaft center 9A, respectively. A plurality of supply side distribution passages 14 (six in the embodiment) are formed in the radial direction at one end of the shaft main body portion 11 and the inner end of the shaft main body portion 11 communicates with the cooling water supply passage 13. A roll shaft side water supply channel (roll shaft side water channel) 15 is formed by 13 and the supply side distribution channel 14.

At the other end of the shaft body 11, a plurality of discharge side collecting passages 17 (6 in the embodiment) are formed in the radial direction, the discharge side collecting passages 17 having inner ends communicating with the cooling water discharge passages 16. Cooling water discharge channel
A roll shaft side drainage channel (roll shaft side water channel) 18 is formed by 16 and the discharge side collecting channel 17. A cooling water supply pipe 2 is connected to the cooling water supply passage 13, and a drainage pipe 3 is connected to the cooling water discharge passage 16.

The roll base material 20 has a cylindrical shape, and is fitted and fixed to the shaft body 11 of the roll shaft 10 by shrink fitting. Grooves 22 are provided in a recessed annular shape at both ends of the shrink fit portion 21. Inside the roll base material 20 in the vicinity of the roll surface, there is a cooling water passage 23 along the direction of the roll axis 9A.
Are formed at predetermined intervals in the circumferential direction. The inside of these cooling water channels 23 is plated, and both ends are closed by blind plugs 24. Further, at both ends of the roll base material 20, a supply-side communication passage 25 or a discharge-side communication passage 26, which are connected to the blind plugs 24 at both ends of each cooling water passage 23, are formed in the radial direction.

The roll base material 20 has a corrosion resistant alloy 28 formed by overlaying on the roll surface. This corrosion resistant alloy 28 is
It is formed by a weld overlay of two or more multi-layer overlays. Here, the weld overlay first layer 28 formed on the roll surface is used.
A weld overlay second layer 28B is formed on A.

At both ends of the roll base material 20, end members 30 are provided.
Are fixed by welding 31. These end members 30 are ring-shaped and are fixed to the roll base material 20 by welding 31 via the outer peripheral edge thereof. The end member 30 is integrally formed with a cylindrical outer baffle plate 32 extending inwardly from the inner peripheral edge thereof, and the inner end of the outer baffle plate 32 is welded 33 to both ends of the roll base material 20. It is fixed. And the outer baffle 32
A plurality of outer water passage holes 34 are formed at predetermined intervals in the circumferential direction on the inner end side. With the above configuration, the roll base material 20
A water supply channel 35 or a drainage channel 36 communicating with the cooling water channel group 23 is formed between the end surface of the cooling water channel 23 and the inner surface of the end member 30.

A roll body side plate 40 is detachably provided over the end surface of the shaft body 11 of the roll shaft 10 and the outer surface of the end member 30 on the inner edge side. These roll body side plates 40 are ring-shaped and have a large number of bolts inside and outside.
It is detachably provided via 41 and 42, and a pair of inner and outer seal members 43 and 44 are interposed. A cylindrical inner baffle plate 45 extending inward at a right angle from the middle portion thereof is integrally connected to the roll body side plate 40 by welding 46, and the inner ends of the inner baffle plate 45 are at both ends of the roll base material 20. Is abutted against. On the outer end side of the inner baffle plate 45, a plurality of inner water passage holes 47 are formed at predetermined intervals in the circumferential direction. Here, the inner water passage holes 47 are arranged so as to be out of phase with the outer water passage holes 34 in the circumferential direction.

With the above configuration, one roll body side plate
A water supply side communication passage 48 that connects the roll shaft side water supply passage (roll shaft side water passage) 15 and the water supply passage 35 is formed inside 40, and inside the other roll main body side plate 40, the roll shaft side drainage passage ( Drain side communication passage that connects the roll shaft side water channel 18 and the drainage channel 36
49 is formed, and the roll main body side plate 40 is provided with the inner baffle plate 45 located in the water supply side communication passage 48 and the drain side communication passage 49.

Further, the water supply side communication passage 48 and the water supply passage 35 form a cooling water distribution passage 50 from the roll shaft side water supply passage 15 to the cooling water passage 23 group, and in the middle of the cooling water distribution passage 50,
Two or more baffles, that is, an inner baffle 45 and an outer baffle 32 are provided. Further, the drainage channel 36 and the drainage side communication channel 49 form a cooling water collecting path 51 from the cooling water channel 23 group to the roll shaft side drainage channel 18, and two or more obstacles are provided in the middle of the cooling water collecting path 51. Plates, an inner baffle 45 and an outer baffle 32, are provided.

The operation of the above embodiment will be described below.
When forming the mold roll 9, the roll shaft 10 and the roll base material are used in order to reduce the welded portion and reduce the cost.
It is manufactured separately from 20 by forging, and both 10,
After shrink-fitting 20, the corrosion-resistant alloy 28 made of, for example, nickel-chromium alloy is overlay welded on the roll surface of the roll base material 20. After that, the end member 30 is fixed to the end of the roll base material 20 by welding 31, 33, and the roll body side plate 40
Are fixed by bolts 41 and 42. As a result, the cooling water distribution path 50 and the cooling water collecting path 51 are formed with a reduced number of welding points, and the baffle plates 32,
45 is placed. After that, blind plug for 23 groups of cooling water channels
24 is installed.

The mold roll for the thin plate continuous casting machine is in contact with the molten steel and directly takes heat to solidify the molten steel.
Since the temperature rise of the mold roll is excessive, it is important to prevent its thermal deformation. Although it is effective to make the mold roll a solid structure to prevent thermal deformation,
It is not economical to make the entire mold roll from a forged product into a unitary structure. That is, as shown in this embodiment, the roll shaft 10 of the mold roll 9 and the roll base material 20
It is desirable to use and in separate configurations, and to use each in combination with an appropriate material and structure including economical efficiency.

As a method of integrating the roll shaft 10 and the roll base material 20, there are welding, casting and casting, and shrink fitting, but the cost is high in welding, and in the casting and casting, the roll base material 20 is cooled to the cooling water passage. It is difficult to control the inclusions that cause the deviation of the processed holes when cutting out the 23 holes. On the other hand, the shrink-fitting method has a low cost, and the roll base material 20 on which the holes have been formed in the cooling water passage 23 can be easily mounted on the long roll shaft 10.

Here, when the roll is used, a heat load is applied to the surface of the roll, and excessive heat deformation stress is concentrated on the shrink fit portion. However, by providing the groove 22 at the shrink fit end of the roll base material 20, Concentration of thermal deformation stress can be eliminated, and it is possible to prevent damage to the shaft core portion due to excessive stress applied to the roll shaft core portion due to thermal deformation of the roll base material 20.

A large cooling capacity is required for the cooling system of the mold used for casting. In particular, if the inside of the cooling water channel is oxidized, the cooling capacity will be significantly lower than the designed cooling capacity. Therefore,
It is conceivable to perform a treatment for preventing oxidation inside the cooling water channel group 23.

As an example, an example in which the inside of the cooling water passage 23 is plated with nickel will be shown. Construction is performed by plating the inner surface of the round hole of the roll base material 20 in which the cooling water channel 23 has been drilled, and then,
The necessary parts are machined. The reason why we did not plate the entire cooling water channel inside the cooling water channel 23 was that it was difficult to visually check the plated area when plating after manufacturing and assembly was completed, beyond the cost problem. In order to remove the influence of the plating layer when some kind of welding repair is required, it is necessary to remove the plating layer over a wide area, and practically, the round hole near the roll surface is cooled. This is because the function is important and the other part is in charge of supplying cooling water, and plating is not necessarily required.

When the mold roll 9 thus constructed is used, the cooling water flows through the following paths. That is, it flows from the water supply pipe 2 to the cooling water supply passage 13, is distributed by the supply side distribution passage 14, and then flows to the cooling water distribution passage 50. When flowing through the cooling water distribution path 50, the cooling water is diffused and mixed by the two baffle plates 45 and 32 to be uniformized, and is evenly supplied to each cooling water path 23 through each supply side communication path 25. To be done. Next, the cooling water flows through each cooling water passage 23 to cool the surface side of the roll base material 20,
Then, it is discharged to the cooling water collecting path 51 via each discharge side communication path 26. After that, the cooling water flows from the discharge side collecting passage 17 to the cooling water discharge passage 16 and is drained through the drainage pipe 3.

In the above embodiment, the cooling water passage 23 has an inner diameter of 15
128 mm round holes are drilled at a position of 30 mm below the surface of the roll. In this case, each cooling water channel 23
It is necessary to supply cooling water evenly. But,
It is not realistic to supply 128 pieces of cooling water from the cooling water supply passage 13 on the roll shaft core 9A. In the embodiment, the cooling water is distributed evenly to both ends of the roll by distributing the cooling water from the cooling water supply path 13 through the six supply side distribution paths (pipes) 14. And, for the six supply side distribution passages 14, the inner baffle plate
Cooling water is evenly supplied to 128 cooling water channels 23 by providing 24 water channel partitions with 45, and by providing 24 water channel partitions with the outer baffle plate 32 in front of the 128 cooling water channels 23. are doing.

Table 1 shows the difference in the overlaying method of the weld overlay first layer 28A and the difference in the penetration depth.

[0049]

[Table 1]

That is, as shown in Table 1, in the usual arc welding overlay method, the average overlay thickness is 3.8 mm,
The maximum value is 4.49 mm, and the minimum value is 3.09 mm, which is a large difference, and the thermal conductivity of the roll base material 20 and the overlay material is high in this mold roll 9 which requires a uniform temperature distribution on the roll surface. In the case of a large difference, this difference between the indentation depths leads to uneven solidification of the obtained slab.

On the other hand, in the reverse polarity soft plasma welding overlay which is the proposed welding overlay method, the average overlay thickness is 3.0 mm, the maximum value is 3.22 mm, and the minimum value is 2.73 mm. The variation in the melt depth is small, and it is suitable as a surface coating method for the mold roll 9. It should be noted that these values show the thickness of the build-up layer and do not show the absolute value of the penetration depth, but the smaller the variation of the penetration depth is, the more suitable for the mold roll 9. Is clearly desirable.

Table 2 shows changes in the hardness (hardness) of the heat-affected zone of the roll base material 20 due to the weld overlay proposed in the present invention at the time of 3-layer overlay.

[0053]

[Table 2]

That is, as shown in Table 2, the first layer (No.
1) is a weld overlay using the reverse polarity soft plasma method, which has a shallow depth of penetration and is evenly melted. Second layer (N
o.2) and the third layer (No.3) were welded with powder plasma (PTA), but they were welded with a large current and had a deep melting depth and sufficient melting. Therefore, if it easily occurs at the time of welding, defects such as insufficient indentation do not occur. Furthermore, the welding tempering that occurs during welding is positively used, and the welding heat affected zone of the roll base material 20 whose Vickers hardness was 580 during the first layer weld overlay (No. 1) , 500 when the second layer is built up (No.2), 500 when the third layer is built up (N
It was 360 in o.3), and it is clear that the part where the toughness had decreased due to hardening during the first layer buildup was recovered.

For reference, the hardness (No. 4) of the portion of the member, which was built up under the same conditions until the third layer, was heat treated according to the conventional heat treatment condition after welding. The heat treatment conditions are set in consideration of the toughness recovery of the heat-affected zone of the roll base material 20 and the softening temperature of the base material. By this heat treatment, the hardness became 320, and some toughness was recovered, but it can be said that it is practically equivalent to the case where heat treatment is not performed.

From the above, the welding tempering generated by welding the second and third layers with a large current is positively utilized to recover the toughness of the roll base material 20 which is lowered during welding. No heat treatment is required. Furthermore, the residual stress of the weld overlay is the maximum at the weld surface, and heat treatment to remove the residual stress after welding cannot be omitted for normal welding or hard overlay when used in the as-welded shape. However, in the build-up of the mold roll 9, the weld build-up is performed to a thickness greater than the required thickness, and the use of welding tempering can be used in combination to remove unnecessary portions.
It is possible to omit the heat treatment after welding.

That is, in the present embodiment, the required weld overlay thickness is 4 mm, and by setting the cutting removal overlay thickness to 3 mm, the maximum weld residual stress is cut by machining after overlaying. By removing it, the heat treatment for the purpose of removing stress in the residual maximum stress portion can be omitted.

Table 3 shows the chemical composition of the members in the weld overlay.

[0059]

[Table 3] That is, as shown in Table 3, when the overlay welding is performed with the welding material of the target composition which is the conventional welding method, the overlay portion is the nickel-based alloy and the roll base material is the iron-based alloy. However, there is a dilution of the components from the roll base material, and especially the iron component fluctuates greatly. On the other hand, by adjusting the welding material and not including the iron component, in the case of the embodiment, it is possible to obtain the overlay layer having the composition that matches the target component.

[0060]

According to the first aspect of the present invention having the above-described structure, the cooling water can be made uniform by diffusing and mixing by the baffle when flowing through the cooling water distribution passage from the roll shaft side water passage, and evenly distributed to each cooling water passage. Can be supplied to.

Further, according to the second aspect of the present invention, the communication passage, the water supply passage, and the drainage passage can be formed at both ends of the roll with a reduced number of welding points, and the baffle plate can be arranged in the communication passage.
As a result, it is possible to reduce the manufacturing cost of the roll main body and to uniformly cool the slab.

According to the third aspect of the present invention having the above-described structure, when flowing through the cooling water distribution passage, the cooling water can be diffused and mixed by a plurality of baffle plates to be uniformized, and the cooling water is evenly supplied to each cooling water passage. be able to.

Further, according to the fourth aspect of the present invention having the above-mentioned structure, the roll shaft and the roll base material are integrated by shrink-fitting, so that the cost can be reduced and the roll base material which has been subjected to the drilling of the cooling water passage can be manufactured. It can be easily mounted on a long roll shaft, and the groove prevents excessive heat deformation stress from concentrating on the shrink-fitted portion when the roll is used, and heat deformation of the roll base material causes excessive heat deformation on the roll shaft core. It is possible to prevent stress from damaging the shaft core.

Moreover, according to the fifth aspect of the present invention having the above-mentioned structure, it is possible to prevent the inner surface of the cooling water passage from being oxidized by the plating treatment and to easily perform on-site repair. According to the sixth aspect of the present invention having the above-described structure, a mold roll having abrasion resistance and low thermal conductivity can be easily obtained at low cost, and can be used by removing abrasion or any scratch during use. Repair to return to the state,
It can be done easily and quickly on site.

Further, according to the seventh aspect of the present invention having the above-mentioned structure, the low alloy steel is formed by a multi-layered structure of two or more layers, thereby causing welding tempering in the roll base material and recovering the toughness of the roll base material. As a result, it is possible to perform the weld overlay on the roll surface, which does not require the stress relief heat treatment of the weld overlay.

According to the eighth aspect of the present invention having the above-mentioned structure, the phenomenon of component dilution in the overlay layer, which occurs due to the difference between the base material component and the overlay component, is utilized. By utilizing dilution, iron can be removed from the components of the weld overlay material during the overlay of the first layer or reduced to a specified component or less to achieve a predetermined target component during overlay overlay, and the meat of the second layer or above By using a welding material having a predetermined build-up component during the build-up, the entire build-up layer can be made to have a predetermined component target, and the reliability of the material components after the welding dilution can be improved.

Further, according to the ninth aspect of the present invention having the above-mentioned structure, the weld overlay of the first layer can be carried out while preventing deep penetration, and the penetration depth can be made uniform so that the physical properties of the mold roll surface can be improved. Can be made uniform, and the welding build-up of the second layer or more can be performed while shortening the welding build-up time and making the weld build-up defect less likely to occur, and at the same time deep penetration can be performed, and at the same time, By using the welding tempering with high heat input welding overlay, the toughness of the roll base material made of iron-based alloy can be restored, and the stress relief heat treatment after the completion of the overlay welding is not necessary. It is possible to do the prime.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a mold roll for twin-roll thin plate continuous casting according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the mold roll for continuous casting of the twin roll type thin plate.

FIG. 3 is a vertical cross-sectional front view of a main part of the same twin roll type mold roll for continuous casting of thin plates.

[Explanation of symbols]

 1 Bearing device 9 Mold roll 9A Roll axis 10 Roll axis 13 Cooling water supply path 14 Supply side distribution path 15 Roll axis side water supply path (roll axis side water path) 16 Cooling water discharge path 17 Discharge side collection path 18 Roll axis side drainage Channel (roll channel side) 20 Roll base material 21 Shrink fit section 22 Groove 23 Cooling channel 28 Corrosion resistant alloy 28A Weld buildup first layer 28B Weld buildup second layer 30 End member 32 Outer baffle plate 35 Water supply channel 36 Drainage channel 40 Roll body side plate 45 Inner baffle plate 48 Water supply side communication channel 49 Drain side communication channel 50 Cooling water distribution path 51 Cooling water collecting path

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B23K 35/30 340 B23K 35/30 340D

Claims (9)

[Claims] 1. A molten metal is supplied to a space formed by a pair of rolls facing each other, and the metal solidified layer formed on the roll surface is pressure-bonded by rotating in a direction in which the rolls facing each other are sandwiched to melt the molten metal. In a mold roll used in a twin roll type thin plate continuous casting machine for manufacturing a thin plate, in the vicinity of the roll surface, a plurality of cooling water channels along the roll axis direction are formed at predetermined circumferential intervals, A cooling water distribution path that connects the end of the cooling water path group and the roll shaft side water path is formed at the end of the roll body, and a baffle plate located inside the cooling water distribution path is provided. Twin roll type mold roll for continuous casting of thin plates. 2. The molten metal is supplied to a space formed by a pair of rolls facing each other, and the metal coagulation layer formed on the roll surface is pressure-bonded by rotating in a direction in which the rolls facing each other are sandwiched to melt the molten metal from the melt. In a mold roll used in a twin roll type thin plate continuous casting machine for producing thin plates, a cylindrical roll base material is externally fitted and fixed on the roll shaft, and this roll base material is made of a corrosion resistant alloy on the roll surface. In addition to forming by a heap, inside the vicinity of the roll surface, a plurality of cooling water channels along the roll axial direction are formed at predetermined circumferential intervals,
By fixing the end member to both ends of the roll base material, between the end surface of the roll base material and the inner surface of the end member, a water supply passage or a drain passage communicating with the cooling water passage group is formed, and the end portion is formed. A roll body side plate is detachably provided across the member and the roll shaft,
A twin roll type thin plate continuous casting mold roll, wherein a baffle plate is provided in a communication passage that connects the roll shaft side water passage and a water supply passage or a drainage passage. 3. A twin roll type thin plate continuous casting according to claim 1, wherein two or more baffle plates are provided in the cooling water distribution path from the roll shaft side water passage to the cooling water passage group. Mold roll. 4. The roll shaft and the roll base material are made of ordinary carbon steel or low alloy steel, and the cylindrical roll base material is externally fitted and fixed to the roll shaft by shrink fitting, and the end of the shrink fitting portion is formed. The twin roll type continuous casting mold roll according to claim 2, wherein a groove is provided in the portion. 5. The twin roll-type thin plate continuous casting mold roll according to claim 1, wherein the inside of the cooling water channel group is plated. 6. The molten metal is supplied to a space formed by a pair of rolls facing each other, and the metal solidified layer formed on the roll surface is pressure-bonded by rotating in a direction in which the rolls facing each other are sandwiched from the melt. In the method of manufacturing a mold roll for twin-roll type thin plate continuous casting for manufacturing a thin plate, a cylindrical roll base material is externally fitted and fixed to the roll shaft by shrink fitting, and then a corrosion-resistant alloy is applied to the surface of the roll base material. A method for producing a mold roll for continuous casting of twin roll type thin plates, characterized in that the above-mentioned corrosion-resistant alloy is processed by forming the above. 7. The twin roll type thin plate continuous according to claim 6, wherein a low alloy steel is used as a roll base material, and a corrosion resistant alloy is formed on the surface of the roll base material by a weld overlay of two or more layers. Manufacturing method of casting mold roll. 8. The weld overlay of the first layer is made smaller than the target component when the overlay is welded, and the overlay of the predetermined component material is performed when the overlay of the second layer or more is provided. Item 8. A method for manufacturing a mold roll for twin-roll thin plate continuous casting according to Item 7. 9. The welding overlay of the first layer is performed by a reverse polarity soft plasma overlaying method or a similar small heat input welding overlaying method,
Then, the welding overlay of the second layer or more is performed by the powder plasma overlay method or the high heat input welding overlay method, and at the same time, the welding tempering is performed by the powder plasma overlay or the high heat input welding overlay. The method for producing a mold roll for twin-roll thin plate continuous casting according to claim 7.