JP3765482B2 - Roll for multi-high mill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a roll for a multi-high rolling mill used for rolling a thin strip, and particularly to a roll for a multi-high rolling mill in which an outer layer made of a cemented carbide is formed on the outer periphery of a shaft made of a ferrous material having excellent toughness.
[0002]
[Prior art]
Tungsten carbide (WC) cemented carbide with excellent wear resistance, rough skin resistance, etc., to meet the demands for higher quality such as improved dimensional accuracy, reduced surface flaws, and improved surface gloss. It is applied to rolling rolls such as wire rods, bar steels and flat steels. 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, and Fe, and often contains carbides such as Ti, Ta, and Nb in addition to WC.
[0003]
For example, Japanese Examined Patent Publication No. 58-39906 describes a wire-rolling roll made of a WC-Co-Ni-Cr WC cemented carbide. This wire rolling roll is a small sleeve roll obtained by sintering a cemented carbide single body, and is fitted to a steel roll shaft material with excellent toughness at a shrinkage fit of about 0.1 / 1000. The roll side is pressed and fixed by a fixing ring, a spacer ring or the like, and mechanically assembled.
[0004]
In the case of this type of roll, many members such as a fixing ring and a spacer ring are required, the assembly structure is complicated, and high assembly accuracy is required. Moreover, since it fixes from a side surface, a sleeve is easy to slip in a rotation direction during rolling. Furthermore, there is a disadvantage that the portion occupied by the cemented carbide, that is, the portion that can be used for rolling is less than half of the roll body length, which is not efficient.
[0005]
In the cold rolling of stainless steel strips, cluster type multi-stage rolling mills such as Sendzimer mill are used. FIG. 5 shows a roll layout of a 20-stage Sendimer mill, which is a type of multi-high rolling mill. In FIG. 5, rolling is performed through a thin strip 18 between an upper roll 11 a and a lower roll 11 b which are rolls for a multi-high rolling mill that is a subject of the present invention.
[0006]
FIG. 4 shows a view of the Sendzimer mill of FIG. 5 as viewed from the exit side. In FIG. 4, a thrust load due to rolling always acts on the upper roll 11a and the lower roll 11b during rolling. Therefore, in order to receive this thrust load, the operation-side thrust bearing 16a and the drive-side thrust bearing 16b are disposed at a position several mm away from the rolls 11a and 11b.
[0007]
With such a configuration, when a thrust load due to rolling is applied, the end surfaces of the rolls 11a and 11b repeat line contact with the end surfaces of the thrust bearings 16a and 16b. At this time, the linear pressure at the contact portion becomes considerably high and sometimes reaches about 2 GPa due to Hertz stress. Therefore, the contact portion must have sufficient hardness to withstand this linear pressure. When the linear pressure at the contact portion is about 2 GPa due to Hertz stress, the hardness of the contact portion needs to be about Hs80.
[0008]
FIG. 3 shows a cross-sectional view of a conventional roll for a multi-high mill. In FIG. 3, the roll 11 for a multi-high rolling mill is composed of a roll main body 12 made of cemented carbide and a cap 13 made of an iron-based material. In order to polish the surface of the roll main body 12, the roll 11 for a multi-stage rolling mill needs to be provided with a center hole for centering the polishing machine at the shaft end of the roll. However, since the roll main body 12 is a cemented carbide, it is difficult to process a center hole in the end surface of its own shaft. Accordingly, caps 13 having a concave cross section made of an iron-based material having better machinability than cemented carbide are shrink-fitted on the outer surfaces of both shaft portions of the roll body portion 12, and the center hole 15 is formed in the end surface 14 of the cap 13. Provided. These caps 13 receive a thrust load due to rolling.
[0009]
[Problems to be solved by the invention]
In the conventional roll for the multi-high rolling mill, when the roll temperature rises during rolling, the shrinkage allowance is reduced due to the difference in the linear expansion coefficient between the roll main body 12 and the cap 13, and the roll main body 12 and the cap 13. There is a high possibility that the axial center of the will shift. Therefore, if the roll 11 is polished in a state where the roll body 12 and the cap 13 are misaligned, the roundness of the roll 11 cannot be ensured.
[0010]
Rolled material rolled by a cluster type multi-high rolling mill is often the final product. Therefore, in order to maintain product quality, the roundness of the roll must be strictly controlled. From this point, the conventional roll for a multi-high mill has a problem because the roll axis is easily displaced during roll polishing and it is difficult to secure the roundness of the roll.
[0011]
Therefore, the present invention provides a roll for a multi-stage rolling mill capable of stably securing the roundness of the roll during polishing of the roll while making use of the wear resistance and surface glossiness which are the characteristics of the cemented carbide. For the purpose.
[0012]
[Means for Solving the Problems]
The roll for a multi-high rolling mill according to the present invention forms an outer layer made of cemented carbide on the outer periphery of the shaft portion made of iron-based material and attaches a ring for receiving a thrust load to the outer periphery of the shaft portion of the shaft material. The center hole is provided in the end surface of the shaft portion of the shaft member.
[0013]
In the present invention, the end surface of the ring protrudes from the end surface of the shaft portion of the shaft member. Further, the ring is harder than the shaft member. Furthermore, the ring is fixed by shrink fitting or screwing.
[0014]
[Action]
The roll for the multi-high rolling mill of the present invention is formed by metal-bonding the outer layer of the cemented carbide to the outer periphery of the shaft of the shaft material made of an iron-based material having excellent toughness. The surface gloss is improved and the outer layer does not slip during rolling.
[0015]
Since the shaft material is an iron-based material, it has good machinability, and a center hole can be easily machined in the end surface of the shaft portion of the shaft material. By directly drilling the center hole in the shaft portion of the roll shaft material, the roll shaft and the center axis of the center hole always coincide with each other, and the roundness of the roll can be stably secured during roll polishing. Further, since there is no difficulty in processing the shaft portion of the shaft member, the degree of freedom in selecting a ring fixing method such as shrink fitting a hollow ring for receiving a thrust load and screw fastening is improved.
[0016]
Since the thrust load due to rolling is received by the ring provided on the outer periphery of the shaft portion of the shaft member, it is better to project the end surface of the ring from the shaft end surface of the shaft member so that the thrust bearing does not directly contact the shaft member of the roll. The protrusion length is preferably 0.1 to 5 mm.
[0017]
Moreover, a high linear pressure acts on the ring which receives the thrust load of rolling due to the line contact with the thrust bearing. Since the thrust bearing normally uses tool steel such as SKD material or SUJ material, the material of the ring needs to have a corresponding hardness. Therefore, the hardness of the contact surface of the ring with the thrust bearing is desirably Hs 60 to 95. On the other hand, the hardness of the end face of the shaft portion of the shaft material is sufficient if it is necessary for the center hole for roll polishing, and is preferably Hs25-60.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic cross-sectional view of a roll for a multi-high mill according to an embodiment of the present invention. In FIG. 1, a roll 1 for a multi-high rolling mill according to the present invention is formed by forming an outer layer 5 made of a cemented carbide on the outer periphery of a trunk portion 3 of a shaft member 2 made of SNCM439 steel by metal bonding and a shaft portion 4 of the shaft member 2. A center hole 7 is provided in the end face 6 of the first. And the ring 8 which consists of a hollow cylindrical iron-type material for receiving a thrust load was fitted to the outer periphery of both shaft parts 4 of the shaft material 2 by shrink fitting. In addition, it fixed so that the end surface 9 of the ring 8 might protrude 2 mm outside from the end surface 6 of the shaft part 4 of the shaft member 2.
[0019]
The cemented carbide forming the outer layer 5 is prepared with WC powder having an average particle diameter of 6 μm, 1 μm Co powder, 1 μm Ni powder, and 1 μm Cr powder, and WC 85%, Co 9.3%, Ni 4 by weight%. 7% and Cr 1% in proportion, wet mixed in a ball mill for 20 hours, and then dried mixed powder is sintered.
[0020]
Since the roll 1 for multi-high rolling mills of the present invention has the center hole 7 directly provided in the shaft portion 4 of the shaft member 2, the shaft core 2 and the center hole 7 always coincide with each other. Therefore, when the roll 1 is polished, the problem of misalignment does not occur as in the prior art, and the roundness of the roll can be secured stably.
[0021]
FIG. 2 shows a schematic cross-sectional view of a roll for a multi-high mill according to another embodiment of the present invention. In FIG. 2, the roll 1 for a multi-high rolling mill is made of an iron-based material for processing a screw portion 10 on the outer periphery of a shaft portion 4 of a shaft material 2 made of an iron-based material and receiving a thrust load on the screw portion 10. The ring 8 was screwed and fastened. A center hole 7 is provided in the end surface 6 of the shaft portion 4 of the shaft member 2. Since the processing of the shaft portion 4 of the shaft member 2 is easy, a method for fixing the shaft member 2 and the ring 8 can be widely selected.
[0022]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the precision of the roundness of roll grinding | polishing can be improved and the roll made from a cemented carbide alloy which can be applied and expanded also for a highly accurate rolling use can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a roll for a multi-high rolling mill according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a roll for a multi-high mill according to another embodiment of the present invention.
FIG. 3 shows a cross-sectional view of a conventional roll for a multi-high mill.
4 shows a view of the Sendzimer mill of FIG. 5 as viewed from the exit side.
FIG. 5 shows a roll layout of a 20-stage Sendimer mill, which is a kind of multi-high rolling mill.
[Explanation of symbols]
1 Roll for multi-high rolling mill, 2 shaft material, 3 trunk, 4 shaft, 5 outer layer,
6 End face of shaft part, 7 Center hole, 8 ring, 9 End face of ring,
10 thread part, 11 roll for multi-high rolling mill, 12 roll body part,
13 cap, 14 end face of cap, 15 center hole,
11a upper roll, 11b lower roll, 16a operation side thrust bearing,
16b Drive side thrust bearing, 18 ribbon

Claims (4)

An outer layer made of cemented carbide is formed on the outer periphery of the shaft part made of iron-based material, a ring for receiving a thrust load is attached to the outer periphery of the shaft part of the shaft material, and a center hole is formed in the end face of the shaft part A roll for a multi-high rolling mill characterized by comprising: The roll for a multi-high mill according to claim 1, wherein an end surface of the ring protrudes from an end surface of the shaft portion of the shaft member. The roll for a multi-stage rolling mill according to claim 1 or 2, wherein the ring is harder than the shaft member. The roll for a multi-stage rolling mill according to any one of claims 1 to 3, wherein the ring is fixed by shrink fitting or screwing.

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