JPH0428442B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a rolling mill that rolls a wide metal plate using work rolls made of ceramics. [Background of the Invention] It has already been proposed to use ceramics for the work rolls of rolling mills, taking advantage of the high hardness and high abrasion properties that ceramics inherently have. For example, US Pat. No. 3,577,619 describes that the work roll of a rolling mill for rolling a wide metal plate is a composite roll consisting of a core and a sleeve, and the sleeve is made of ceramics. However, in general, increasing the bonding strength at the interface between metal and ceramics involves technical difficulties, and when the core is made of iron alloy, depending on the material of the ceramic, it is difficult to increase the bonding strength between ordinary ceramics and iron alloy. Since the difference in their respective coefficients of thermal expansion is too large, peeling at the interface is likely to occur due to thermal history etc. when the work roll is used. On the other hand, when the entire work roll is made of ceramics, ceramics are generally strong against compressive stress but weak against tensile stress, so depending on the rolling conditions, the roll may break due to the bending load acting on the roll shaft. There are things to do. Additionally, the shaft of a work roll generally requires machining such as screws and keyways, but ceramics is a hard material that is difficult to machine, so machining may be impossible or possible. As time went on, processing costs remained extremely high. A similar technology in which ceramics are used for wire rod rolling is disclosed in, for example, Japanese Patent Application Laid-Open No. 1986-
There are those described in Publication No. 21413, West German Patent DT2449874, and document "Sumitomo Electric" No. 129, pages 107 to 113. In these examples, ceramics are made into a hollow ring shape, which is fixed using a metal shaft and a stopper.
constitutes a role. The reason for this is the aforementioned Japanese Unexamined Patent Publication No. 59
As described in Japanese Patent No. 21413, ceramics are much more brittle than tool steel, so it is technically difficult to obtain the toughness required for the roll shaft. In other words, even when ceramics were used for rolling rolls, they were made into a ring shape and combined with a central metal shaft. In addition, since the wire rod rolling roll using the above-mentioned ceramics has a recess in the part where the wire comes into contact, it is of course impossible to roll a wide metal plate. There are many disadvantages in rolling a wide metal plate as a roll surface, and it is difficult to put it into practical use. First, rolling a wide metal plate requires an extremely high rolling load compared to wire rod rolling, but under such a high load, the rolling rolls become curved, making rolling difficult. It is virtually impossible to roll wide and thin metal sheets that require rolling loads. Furthermore, when reinforcing rolls are used to prevent the rolls from curving, the rolls are subjected to a large compressive load in the radial direction during rolling. In this case, the ring-shaped ceramics used for the rolling rolls are easily destroyed. This is because the metal central shaft that makes up the rolling roll and the ring-shaped ceramic are not completely connected.
This is because the ring-shaped ceramics easily deform and break when subjected to a load. Additionally, if this gap is not provided, the difference in thermal expansion coefficients between the metal (center shaft) and ceramics (ring) will cause large tensile stress to occur in the ceramic ring when the temperature rises during rolling, causing the ring to break. It becomes easier to do. As mentioned above, there are examples of ceramics being used as rolls for rolling wire rods, but this is because a metal with high toughness is used for the central shaft, and the entire roll must be made of brittle ceramics. Due to the fact that it is difficult to roll a wide metal plate with a ceramic roll, and because it is difficult to use a conventional wire rod rolling roll using ceramics to roll a wide metal plate, it is difficult to roll a wide metal plate with a ceramic roll. It is considered difficult to realize even by experts, and there has never been an example of ceramic work rolls being used for rolling wide metal sheets. [Object of the Invention] The object of the present invention is to provide a rolling mill that allows easy machining of ceramics, obtains a work roll with high reliability in terms of strength, and prevents the work roll from bending in the rolling direction. It is to provide. [Summary of the Invention] The present invention breaks away from conventional thinking and uses a new idea to realize the world's first wide metal plate rolling mill that uses ceramics for work rolls. The present invention provides a rolling mill in which a work roll is rotated sub-rotated by the rotational drive of an intermediate roll or a reinforcing roll to roll a wide metal plate, and the work roll is made of silicon carbide, silicon nitride, or sialon in the shape of a long round bar. , alumina, zirconia, or a composite of these materials, and a bearing is provided in contact with each end surface of the work roll to restrain the axial movement of the work roll. In addition, the rolling mill is characterized in that support rolls are disposed in contact with the work rolls before and after the work rolls in the rolling direction to restrain movement of the work rolls in the rolling direction. Ceramics is a difficult-to-process material, but since the ceramic roll used in the present invention has a simple round bar shape, machining of the body and end faces of the roll is easy, and the precision machining finish allows for a smooth surface. can do. The ceramic material is preferably one with high strength, such as silicon carbide, silicon nitride, sialon, alumina, zirconia, or a composite material thereof. Cermet or cemented carbide may also be used as the roll material, but these all have a microstructure of ceramic particles bonded with metal, so
The metal tends to adhere to the rolled material during rolling, and the surface gloss of the resulting rolled material is inferior to that of ceramic rolls. Especially in hot rolling,
As stated in Publication No. 21413, the metal part of the roll softens or oxidizes, which significantly reduces its effectiveness as a binder, causing ceramic particles to fall off, making the roll surface rough, and accelerating wear. Become. When the work roll is rotated by the rotational drive of the intermediate roll or reinforcing roll, the work roll is pressed against the reinforcing roll or the intermediate roll, so the force acting on the work roll is mainly compressive stress, and the force acting on the work roll is mainly compressive stress. The stress is negligible, and the characteristics of ceramics, which are strong against compressive stress, can be effectively used, and the strength can be highly reliable. Further, the work roll of the present invention is round bar-shaped,
Since there are no stress-concentrating parts such as screws or keyways, the shape can be highly reliable. In the present invention, the work roll is supported so as to restrict movement of the work roll in the axial direction and rolling direction. To restrain movement in the axial direction, bearings are disposed in contact with each end surface of the work roll. In order to restrain movement in the rolling direction, support rolls are disposed in contact with the work rolls at the front and rear of the work rolls in the rolling direction so as to sandwich the work rolls. The support roll is essential for positioning the work roll, but the support roll prevents the work roll from bending in the rolling direction during rolling. Next, it is generally known that in a rolling mill, when the rolling load increases, the rolls bend, and the thickness of the rolled plate at the center of its width increases. Therefore, as a means of preventing this and producing a rolled material with a uniform thickness, it is common practice to reduce the diameter toward the end of the body of the roll, that is, to provide a crown. Also in the rolling mill of the present invention, it is desirable to provide a crown on at least one of the intermediate roll, reinforcing roll, work roll, and support roll. Note that by providing a crown on the support roll that supports the work roll, it is possible to prevent the work roll from bending in the rolling direction. [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described based on the drawings. Figures 1 and 2 show an embodiment of the present invention, and 1 is a work roll made of high-strength sialon with a bending strength of 80 kgf/mm ² , and is a round bar-shaped roll with a diameter of 20 mm and a length of 100 mm. are doing. This work roll 1
is manufactured by machining a round bar-shaped material with a diamond grindstone. The dimensional accuracy and surface accuracy of the work roll 1 are equivalent to those of a metal roll. A reinforcing roll 2 consisting of a shaft and a body is pressed against the work roll 1, and the work roll 1 is rotated by rotation of the reinforcing roll 2. The shaft portion of the reinforcing roll 2 is rotationally driven by an electric motor (not shown) via a universal joint (not shown) and a reduction gear (not shown). In addition, the shaft of the reinforcing roll 2 is equipped with a bearing (not shown) equipped with a rolling reaction force on the shaft.
is being communicated to. A steel ball 6 is arranged on each end surface of the work roll 1 so as to be in contact with the center of the end surface, and the steel ball 6 is rotatably supported by a steel ball support 7. Therefore, the movement of the work roll 1 in the axial direction is restricted. Furthermore, the sliding speed between the work roll 1 and the steel balls 6 is reduced to prevent seizure or the like from occurring. A support roll 3a is disposed in contact with the work roll 1 before and after the work roll 1 in the rolling direction, and another support roll 3b is further disposed in contact with the support roll 3a. Another support roll 3b serves to reinforce support roll 3a. Support roll 3a and another support roll 3b are supported by bearings 5. The bearing 5 is housed in a bearing box 4. Since support rolls 3a are disposed in contact with the work roll 1 before and after the work roll 1 in the rolling direction, movement of the work roll 1 in the rolling direction is restrained. 8 is a rolled material rolled by the work roll 1, which has a width of 50 mm and a thickness of 50 mm.
A 0.5mm mild steel plate is used. As a result of conducting a rolling experiment while rotating the reinforcing roll 2 at a speed of 30 revolutions per minute, the rolled material 8 was sufficiently rolled. That is, by repeating rolling, a rolled material with a thickness of 5 mm could be rolled to a thickness of 0.1 mm. In this case, a rolled material with good gloss could be obtained without damaging the ceramic work roll 1. A second rolling example using the rolling mill of the present invention shown in FIGS. 1 and 2 will be described. However, work roll 1 has a bending strength of 50 kg instead of Sialon.
A ceramic roll made of silicon carbide of f/mm ² was used, and the surface roughness was ground to 0.2 μm or less, and a work roll made of die steel was also prepared for comparison, with the same surface as the silicon carbide roll described above. It was used after being ground to a rough finish. Width 28mm for rolled material,
Using mild steel with a thickness of 0.4 mm, the same material was repeatedly rolled at a rolling speed of 3 m/min without applying tension to the plate, using 10% water-soluble oil dissolved in water as a lubricating coolant. The minimum possible plate thickness was determined. The results are shown in Table 1. A rolling mill using the silicon carbide of the present invention for work rolls was able to reduce the plate thickness to 13 μm. When die steel was used for the work roll, the thickness could be reduced to 26 μm.

[Table] With the rolling mill of the present invention, it was possible to obtain a mild steel plate with a thickness approximately 1/2 that of the conventional method (using die steel). Note that the minimum thickness that can be rolled is the limit thickness beyond which it cannot be made thinner.If the roll diameter is the same, the higher the Young's modulus of the roll material, the smaller the flattening deformation of the roll during rolling. You can get thin plates. The Young's modulus of silicon carbide used here is
It was 40,000 Kgf/mm ² , which is higher than the 21,000 Kgf/mm ² of die steel, and therefore, the rolling mill of the present invention was able to obtain a thinner plate. In the third example described below, a roll having a bending strength of 70 mm is used as a round bar with a diameter of 40 mm and a length of 350 mm.
Kgf/mm ² made of sialon and die steel were prepared. The surface roughness of the roll was finished by grinding to 0.15 μm or less. This roll was installed as a work roll in a Sendzimir rolling mill, and stainless steel was rolled. Originally, the Sendzimir rolling mill was not even supposed to incorporate ceramic work rolls, but the work rolls were shaped like round bars, and multiple rolls were arranged around the work rolls.
The rolling mill of the present invention can be constructed by using high-strength ceramics for the work rolls because of the structure in which the movement of the work rolls in the rolling direction can be restrained and thrust bearings are also arranged to support the end faces of the work rolls. Note that the rolling mill of the present invention can also be configured for a lawn type 20-high rolling mill or the like by replacing the work rolls with high-strength ceramics. The prepared stainless steel to be rolled is austenitic with an initial thickness of 1.20 mm, width of 125 mm, and length of 500 mm.
It is wound into a coil shape of m. This material to be rolled was rolled 10 times at a rolling speed of 10 m/sec while applying tension, and was finally thinned to a thickness of 0.4 mm. The rolling results are shown in Table 2. With the rolling mill of the present invention that uses Sialon work rolls, the gloss of the rolled product (final rolled product) is 58%, which is approximately 29% higher than when conventional die steel work rolls are used. did. This is because Sialon rolls are hard to wear, so the surface roughness of the rolls remains smooth and almost unchanged from the beginning, and Sialon does not easily adhere to the stainless steel material to be rolled. There are two reasons for this. On the other hand, with the die steel roll, wear progressed during rolling, and eventually the roll surface lost its gloss and became noticeably cloudy.

〔Effect of the invention〕

As described above, the present invention uses a roll made of a long round bar-shaped high-strength ceramic as a work roll, and a bearing is disposed in contact with each end face of the work roll to restrain the axial movement of the work roll. In addition, the movement of the work rolls in the rolling direction is restrained by placing instruction rolls in contact with the work rolls before and after the work rolls in the rolling direction, resulting in a shape that is easy to machine and highly reliable in terms of strength. It is now possible to use a rolling mill for wide metal plates equipped with ceramic work rolls, which reduces wear on the work rolls, improves the surface gloss of rolled products, and reduces the thickness of products that can be rolled. There is.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the arrangement of rolls of a rolling mill according to an embodiment of the present invention, and FIG.
It is a sectional view taken along the line A. 1... Work roll, 2... Reinforcement roll, 3a,
3b...Support roll, 4...Bearing box, 5...Bearing, 6...Steel ball, 7...Steel ball support.

Claims (1)

[Scope of Claims] 1. A rolling mill in which a work roll is rotated sub-rotated by the rotational drive of an intermediate roll or a reinforcing roll to roll a wide metal plate, and the work roll is made of silicon carbide or silicon nitride in the shape of a long round bar. A roll made of single high-strength ceramic, such as ceramic, sialon, alumina, zirconia, or a composite material thereof, is used, and bearings are disposed in contact with each end surface of the work roll, and the roll is rotated in the axial direction of the work roll. A rolling mill characterized in that the movement of the work roll in the rolling direction is restrained by disposing support rolls in contact with the work roll before and after the work roll in the rolling direction. 2. The rolling mill according to claim 1, wherein at least one of the intermediate roll, reinforcing roll, work roll, and support roll is provided with a crown.