JPS6231042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for manufacturing a water-cooled roll using a hot isostatic pressing method (hereinafter referred to as HIP method), which is particularly easy to manufacture, and has uniform wear characteristics on the roll surface.
The present invention relates to a method for producing water-cooled rolls that are less prone to damage even during long-term operation.

Conventionally, commonly used water-cooled rolls are manufactured by first manufacturing a roll shaft, forming a water channel on its surface by cutting, etc., and then shrink-fitting a sleeve to form the roll surface on the outside. However, this method requires a large number of steps, and in particular, the operation of fitting and forming the outer sleeve requires consideration of compatibility with the roll axis.
It is extremely complicated, and the joining of the roll shaft and sleeve is troublesome, and the surface properties of the outer roll include the following various problems, similar to conventional hot rolling rolls.

In other words, in the case of general-purpose hot rolling rolls, there are many that are made as ingots from molds, or that are forged into roll shapes after ingot making, and then machined and heat treated. Because hot rolling rolls need to ensure wear resistance in hot conditions,
Since high carbon steel containing 14 to 2.4% C and 0.5 to 3% Cr is used, eutectic carbides are likely to crystallize, and even if they are rapidly cooled after ingot formation, they will reach deep from the roll surface. As the cooling rate slows down, the eutectic carbides produced during solidification gradually become coarser.
Coarse eutectic carbides formed in this way cannot be made finer by forging or heat treatment, so if these carbides are exposed to the surface layer after re-grinding, they will be removed from the surface. This leads to the problem that unevenness is formed on the roll surface and is transferred as a scratch on the product.

In addition, in conventional forged rolls, the primary structure formed during solidification is large, and the boundaries thereof cause large fire cracks during use of the roll, resulting in even greater damage to the product.

The boundary between the eutectic carbide and the matrix is also considered to be a cause of fire cracks.

The above is a case of a general-purpose hot rolling roll, but the same applies to the sleeve of a conventional water-cooled roll, and the formation of unevenness on the roll surface and the occurrence of product scratches are major problems that must be solved. .

The present invention has focused on the above-mentioned actual situation, and has developed a water cooling system that is capable of producing a uniform cooling effect without causing unevenness or cracks even when a relatively deep layer is exposed to the surface due to re-cutting, etc. The first purpose is to provide a roll, and the second purpose is to provide such a water-cooled roll by simple means, and as a means to achieve that purpose, the roll surface layer is
This project establishes a method for forming powder metal sintered bodies using the HIP method.

A method of forming a roll surface layer by the HIP method has already been proposed in Japanese Patent Application Laid-Open No. 47-2851 prior to the filing of this application, but this method covers the entire roll with a metal capsule to form the roll surface layer. The roll is filled with a predetermined metal powder, and then the entire roll is loaded into a HIP furnace and subjected to HIP treatment, which has the following problems in practical use. In other words, since the entire roll is charged into the HIP furnace, in the case of large rolls, it takes up a corresponding amount of space inside the large HIP furnace.
Since the HIP treatment section is only the surface layer of the roll body, the HIP treatment efficiency is extremely poor, and the energy cost and atmospheric gas cost per unit weight of the required HIP treatment section are extremely high, making it impractical. Therefore, the rolls that can be manufactured by this method are limited to extremely small rolls. In addition, the roll support part supported by the roll bearings is usually made of heat-treated low alloy steel with high toughness;
When subjected to HIP treatment, the crystal grains become coarser, resulting in a significant decrease in toughness, and recovery from this is extremely difficult. Especially for recycled rolls, the dimensions of the roll support part are already the specified dimensions, and HIP
Since cutting cannot be performed on the supporting portion after processing, there is no way to correct the deformation of the supporting portion that inevitably occurs due to HIP processing, and therefore it cannot be applied to recycled rolls. .

Thus, the present invention eliminates the drawbacks of the conventional roll manufacturing method using the HIP method, and provides a roll manufacturing method using the HIP method that has high HIP processing efficiency, does not reduce the toughness of the roll support part, and can be applied to recycled rolls. The second purpose is to do this, and as a means to achieve this purpose, the roll is divided into the main body part that requires HIP treatment and the roll support part that does not require HIP treatment, and after HIPing only the roll body part, The idea is to integrate the two by welding.

Therefore, the feature of the present invention is that the part of the outer circumferential surface of the solid roll core where the metal powder sintered layer is formed has a layer that is continuous in the longitudinal direction of the roll core.
The above cooling water pipe is arranged, a metal capsule is attached to the outer periphery of the solid roll core material so as to form an annular space serving as a metal powder filled layer, and the inside of the cooling water pipe is communicated with the outside of the metal capsule,
Subsequently, the space is filled with metal powder and sealed without being degassed or degassed, and then hot statically in a high-temperature, high-pressure gas atmosphere with the inside of the cooling water pipe communicating with the atmosphere. Hydraulic press treatment is applied,
The metal powder is densely sintered and integrated with the solid roll core material 1, and if necessary, roll supporting members are bonded and integrated on both sides thereof.

Hereinafter, the present invention will be further explained in detail with reference to the accompanying drawings.

FIG. 1 shows one embodiment of the method of the present invention, in which a required length is provided in the metal powder sintered layer forming portion to form a cooling channel parallel to the axial direction on the outer circumferential surface of a solid roll core material 1. A concave groove 8 is formed throughout the roll core material 1, and the concave groove 8 communicates with communication holes 9, 9' drilled from both ends of the roll core material 1 through the interior of the core material 1. are arranged in the grooves 8 to form a cooling water channel system within the roll.

Note that the number of grooves 8 parallel to the axial direction provided on the outer periphery of the roll core material 1 is not necessarily one;
In view of the efficiency of water-cooled rolls, it is normal that the number of grooves 8 is one or more, and if there are a plurality of grooves 8, they are arranged at appropriate intervals on the outer periphery of the roll core material 1.
Both ends of the plurality of grooves 8 are connected to the inner ends of the holes 9 and 9' from both ends via radial portions, respectively.
Both ends of a cooling water pipe 10 disposed in the groove 8 are inserted and fixed in an airtight manner into the holes 9, 9'.

Thus, a cylindrical metal capsule 3 is attached to the outer periphery of the solid roll core material 1 that forms the cooling water channel system within the roll so as to form an annular space 2 that will become a metal powder filled layer, thereby forming an outer roll layer. However, the capsule 3 is integrally fixed to the roll core material 1 by appropriate welding or the like, and thereby the annular space 2 is filled with a predetermined metal powder 4, and the subsequent
Preparations will be made to enter the HIP process.

The capsule 3 is assembled to the roll core material 1 by first filling the capsule bottom 3a and body 3b with the metal powder 4 while fixing them to the roll core material 1, and then fixing the lid 3c. When the space is filled with powder at a packing density of about 60 to 75% of the true density ratio in this way, the annular space 2 is
Evacuate residual air inside or seal without evacuating. In addition, even in the case of sealing without degassing, the gas generated when welding the lid 3c to the body 3b and the roll core material 1 is released to the outside, and there is no welding such as pits or blowholes in the welded part. In order to prevent defects from occurring, the degassing pipe 1
2 is necessary.

On the other hand, the solid roll core material 1 has a roll body portion 1a.
roll support part 1 that supports the roll.
Since both portions b and 1b' are not integrated, its length is slightly longer than the length of the metal powder coating layer. However, the roll support part 1
It is necessary to provide b and 1b' on both sides of the solid roll core material 1 in order to support the roll, and therefore,
The solid roll core material is divided into a roll body portion 1a and roll support portions 1b, 1b', and only the roll body portion is assembled and loaded into a HIP furnace and subjected to a predetermined HIP treatment. At this time, the holes 9, 9' and the cooling water pipe 10 are placed in a high-temperature, high-pressure gas atmosphere while being in communication with each other, so it goes without saying that the HIP process is performed while in communication with the atmosphere.

Furthermore, since the assembly does not include a roll support portion as described above, the HIP furnace space can be utilized more effectively, and large rolls can be HIPed in a relatively small furnace.

The powder packed bed that has been subjected to HIP processing becomes a dense sintered body with a medium-thin shape with a higher deformation rate toward the outer diameter of the roll, unlike a general HIP-treated body that shrinks approximately similar to its original shape. It is very different. For this reason,
A large tensile stress acts on the joints 6 and 7 of the metal capsule with the roll core material, and during the HIP process, some test materials were observed to break at the weld 7, but the capsule If the wall thickness of the attachment part 6 to the roll core material is made thicker than other parts so that the leg length of the welded part 7 can be increased, breakage at this part will not be recognized and it will be effective to prevent breakage. There was found.

In addition, the shape of the sintered layer becomes shorter toward the outer diameter, and therefore the effective length of the roll becomes shorter. By making the shape of the body 3c or the bottom 3a tapered outward toward the outer diameter, both ends of the sintered body after HIP treatment can be made to be substantially perpendicular to the roll core material. I can do it.

In addition, when using a capsule shaped like the one shown in Figure 1, the central part of the sintered layer tends to be medium-thin, and as a result, the amount of outer surface cutting increases after HIP treatment, resulting in a thinner effective sintered layer thickness. However, in order to prevent this, the shape of the capsule body 3b is made into a medium-thick barrel shape in consideration of the large amount of deformation in the central part. , it can be made almost flat, the amount of cutting after HIP can be reduced, and the effective sintered layer can be increased.

When the HIP process is completed, the object to be processed is taken out of the furnace, and the metal capsule covering the metal powder sintered layer is removed by cutting, acid dissolution, or other appropriate means, and the sintered layer surface is polished, quenched, or tempered. Perform predetermined processing and heat treatment such as.

Next, roll support parts 1b, 1b', which have been formed in advance, are metallurgically or mechanically joined to both ends of the roll core material 1.

As a metallurgical joining method, electroslag welding or electrogas welding is a typical method, and as a mechanical joining method, a flange is attached to each joining end of the solid roll core material 1 and the support members 1b and 1b'. Any method can be adopted, such as forming the flange and fixing the flange part with bolts and nuts, or forming a shape that allows both to fit together and connecting them with a key pin, etc., but the load on the rollers should be taken into consideration. What is necessary is to select an appropriate joining means.

Note that during the above joining, the roll support portion 1
b, 1b' are provided with supply/drainage holes 5, 5' that penetrate in the longitudinal direction and communicate with the holes 9, 9' in the roll body, and connecting pipes 1 are connected to the supply/drainage holes 5, 5'.
1 and 11' so that they protrude, and the protruding parts
After being inserted into the holes 9 and 9' formed at both ends of the HIP-treated roll body part 1a, the roll body part 1a and the roll support parts 1b and 1b' are integrally joined.

Next, FIG. 2 shows a case in which a spiral waterway is formed, whereas the straight waterway is shown in FIG. Further, holes 9 and 9' are bored from both ends of the roll core material through the inside of the core material to communicate with both ends of the spiral groove, and a cooling water pipe 10 is placed in the groove 8. At the same time, both ends of the roll are hermetically inserted and fixed into the holes 9 and 9' to form a cooling water channel system, and the roll is rolled in exactly the same manner as described above, except that it prepares for the formation of the outer metal powder sintered layer by the subsequent HIP treatment. Water-cooled rolls can be manufactured that have spiral channels inside.

Further, the same applies even when the cooling water channel has a shape other than the above straight or spiral shape, and it is possible to manufacture a water cooling roll having a water channel according to the requirements.

Note that the above explanation does not include the roll support part in the assembly before HIP processing, and only the annular space formed on the outer periphery of the roll body of the roll core material is filled with metal powder, and the roll is preformed. support part
After the HIP process is completed, the roll supporting parts 1b and 1b' are connected to both ends of the roll core material, and the roll support parts 1b and 1b' can be made using the small diameter roll core material and the metal capsule, respectively, either separately from the roll core material 1 or integrally. Similarly to the above, it is also possible to fill the annular space with metal powder, perform HIP treatment, and provide this at both ends of the roll core material 1, which is included in the present invention.

Next, FIG. 3 shows an example in which grooves are not formed on the outer surface of the solid roll core material 1, whereas in FIGS. 1 and 2, grooves are not formed on the outer surface of the solid roll core material 1. A plurality of cooling water pipes 10 are arranged in the section, and both ends thereof are connected to connecting pipes 16, 16', and are formed by metal capsules 3 arranged on the outer peripheral surface of the solid roll core material 1. The annular space 2 has an airtight structure.

The connecting pipes 16, 16' perform the same functions as the connecting pipes 11, 11' in FIG. 1, and the rest of the structure is the same as the embodiment shown in FIGS. 1 and 2.

As described above, the method of the present invention simplifies the production of conventional water-cooled rolls, and has the effect of easily providing required water-cooled rolls without being constrained by the shape of the cooling water channel system inside the roll. The properties of the rolls also have various characteristics as described below.

(1) Since the roll surface layer is formed from metal powder using the HIP method, there are no coarse eutectic carbides on the roll surface, and there is less chipping due to thermal and mechanical stimulation, and it can be used for a long time. It is durable and does not damage the product surface.

(2) Since the structure of the metal powder sintered layer is uniform, even if the surface layer is ground during repair, coarse eutectic carbides will not be exposed, and even a repaired roll will have the same performance as a new roll. keeping.

(3) Fire cracks are small, making the effects of (1) and (2) above even more pronounced.

(4) Since the roll is divided into the main body part that requires HIP treatment and the roll support part that does not require HIP treatment, only the main body part is subjected to HIP treatment.
The space inside the HIP processing furnace can be used effectively, and costs can therefore be significantly reduced compared to the case where the entire roll is charged into the HIP processing furnace.

(5) Since the roll support portion is not subjected to HIP treatment, the properties of the support portion that require toughness are prevented from deteriorating.

(6) If a method of mechanically joining the roll supporting part and the main body part is adopted, when recycling a used roll with a worn surface, the main part and the supporting part are separated and the main part is sintered with metal powder. Since the layers can be formed and the support parts can be joined again, the present invention can also be applied to the regeneration of rolls.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of the method of the present invention, Fig. 2 is a schematic diagram showing a modified embodiment of the cooling water channel, and Fig. 3 is a schematic diagram of main parts showing another embodiment of the cooling water pipe installation. . DESCRIPTION OF SYMBOLS 1... Solid roll core material, 1a... Roll body part, 1b, 1b'... Roll support part, 2... Annular space, 3... Metal capsule, 4... Metal powder,
5, 5'... Supply/drain hole, 8... Concave groove, 9, 9'...
...Communication hole, 10...Cooling water pipe, 11, 11', 1
6,16'...connecting pipe.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a water-cooled roll having a roll made of a sintered metal powder layer on the outer circumferential surface of the solid roll core material 1 and having a cooling water channel in the roll, in which: 1. One or more cooling water pipes 10 continuous in the longitudinal direction of the roll core material 1 are arranged in a portion of the outer peripheral surface where the metal powder sintered layer is to be formed, and a metal powder filled layer is formed on the outer peripheral portion of the solid roll core material 1. A metal capsule 3 is attached to form an annular space 2, and the inside of the cooling water pipe 10 is communicated with the outside of the metal capsule. Subsequently, the space 2 is filled with metal powder 4, and the metal powder 4 is degassed or deaerated. After that, the cooling water pipe 10 is sealed under a high temperature and high pressure gas atmosphere.
A method for producing a water-cooled roll, characterized in that the metal powder is sintered densely and integrated with the solid roll core material 1 by hot isostatic pressing while the inside thereof is in communication with the atmosphere. . 2. One or more concave grooves 8 continuous in the longitudinal direction of the roll core material are formed in the portion of the outer peripheral surface of the solid roll core material 1 where the metal powder sintered layer is to be formed, and the core material is further formed from both ends of the roll core material. Holes 9 and 9' communicating with the groove 8 were bored through the interior, and a cooling water pipe 10 was placed in the groove 8, and both ends of the pipe were airtightly connected to the communication holes 9 and 9'. 2. The method of manufacturing a water-cooled roll according to claim 1, wherein a metal capsule 3 is subsequently attached to the outer periphery of the solid roll core material 1 so as to form an annular space 2 that becomes a metal powder-filled layer. 3. The solid roll core material 1 is divided into a roll body portion 1a and roll support portions 1b, 1b' having supply and drain holes 5, 5' extending in the longitudinal direction and communicating with the cooling water pipe 10 of the body portion. , roll body portion 1a
A method of manufacturing a water-cooled roll according to claim 1 or 2, wherein the metal powder sintered layer is formed on the metal powder sintered layer, and then the roll support portions 1b, 1b' are integrally joined to both sides of the metal powder sintered layer. 4 Roll support portions 1b, 1b supply and drainage holes 5,
Connecting pipes 11, 11' are attached to the holes 9, 9' of the roll main body portion 1a so as to protrude from the connecting pipes 11, 11'.
4. The method of manufacturing a water-cooled roll according to claim 3, wherein the roll body portion 1a and the roll support portions 1b, 1b' are joined and integrated after being inserted into the water-cooled roll.