JP2529846B2 - Cavity rolling method for clad wire rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a hole rolling method for a clad wire rod.

[Prior Art] Conventionally, in continuous rolling of a wire rod material by a hole type, rolling is performed by appropriately combining the rolling methods shown in FIGS. 10 to 12 depending on the shape of the material or the cross section of the product. . 10 to 12, 1 is a rolling element, 2 is a hole type roll, FIG. 10 is a square-diamond rolling, FIG. 11 is a round-oval rolling, and FIG. 12 is a square-oval rolling. ing.

In such hole rolling of wire rod material, since the width and thickness of the rolled material are approximately the same, the width of the rolled material during rolling is large and the vertical dimension of the rolled material is reduced. The oval dimension of the material increases from the original dimension, resulting in a flat rolled material. Therefore, in the case of the hole type rolling of the wire rod, it is usually performed (for example, in the Steel Manual
The plate on page 865 (Fig. 10.4), the size of the rolled material rolled in the preceding pass is reduced in the oval direction in the next pass, and the rolling is repeated in multiple passes with these two passes as one unit. That is, the rolled material is flattened by the reduction in the preceding pass, but in the subsequent rolling in the next pass, it is usually returned to a shape having the same width and thickness in order to secure the stability of rolling.

Therefore, according to the conventional hole-rolling method for wire rods, as shown in FIG. 2, the rolling material is alternately rolled down in each of two directions orthogonal to each other, so that horizontal rolling mills and vertical rolling mills are alternately arranged. However, a mill arrangement that changes the rolling direction for each pass is common. When the horizontal rolling mills are continuously arranged, the flat-shaped rolling material is twisted by 90 degrees with a twister and engaged with the horizontal rolling mill of the next stand. Is also a rolling process in which the directions are alternately changed.

[Problems to be Solved by the Invention] However, in the above-described conventional wire rod rod-shaped rolling method, when the rolling material is alternately rolled from two directions orthogonal to each other, the cross-sectional shape of the rolling material is reduced. However, since one side has a flat shape in the rolling direction, but the other rolling direction does not have a flat shape, the metal flow inside the rolled material is not uniform in both rolling directions. Therefore, for example, as in the clad material 10 shown in FIG.
Considering rolling a material in which the inner layer portion 11 has a circular shape and the outer layer portion 12 has a square shape, the inner layer portion 11 after finishing rolling has a flat shape, and a uniform outer layer thickness in the circumferential direction of the cross section of the clad material 10. Cannot be obtained (see FIG. 4 (B)).

It should be noted that if an extruding process is applied to the clad material instead of rolling, a uniform deformed state of the inner layer portion can be obtained, but the extruding process is completely disadvantageous compared to the rolling method in terms of productivity and the like. is there.

An object of the present invention is to make it possible to uniformize the strain in the inner layer portion in the hole rolling of the clad wire rod material including the inner layer portion and the outer layer portion.

[Means for Solving the Problems] The present invention relates to a method for rolling a clad wire rod rod, comprising rolling the clad wire rod rod including an inner layer portion and an outer layer portion in a plurality of passes in each of two directions orthogonal to each other. The width-to-thickness ratio on the exit side of each rolling pass is 1.
The number of times of reduction passes that results in a flat shape exceeding 1 time and the number of times of reduction passes that results in a flat shape in which the ratio of the thickness of the material to be rolled to the width exceeds 1.1 times are made approximately equal.

[Operation] In a clad wire rod hole rolling method of rolling a rolled material of a clad wire rod composed of an inner layer portion and an outer layer portion from each of two directions orthogonal to each other, not only in one rolling direction but also in the other rolling direction. If the rolled material is flattened even in the rolling direction, it is considered that the metal flow in the inner layer portion of the rolled material can be made uniform.

That is, as shown in FIG. 1, the clad wire rod material roll rolling method of the present invention allows the rolling material to be flattened in a flattening direction by continuously rolling the rolling material in the same direction twice, for example, as shown in FIG. The rolling material is flattened in both two directions orthogonal to each other by varying the degree of change so that the metal flow in the inner layer portion of the rolling material can be made uniform.

Therefore, according to the present invention, even in the clad material 10 shown in FIG. 3, for example, the internal strain caused by rolling is made uniform, and the cross-sectional shape of the inner layer portion 11 after rolling is as shown in FIG. 4 (A). It can be rounded.

The following method is conceivable as a specific method for flattening the rolled material in both directions orthogonal to each other.

When the horizontal and vertical rolling mills are arranged alternately, like the diamond-to-diamond rolling or the oval-to-oval rolling, the square rolling is omitted in the former and the round rolling is omitted in the latter, and flattened in one direction. A method is conceivable in which the formed material is flattened in the other direction in one pass of the next pass. However, in this case, the processing amount becomes very large,
There are some problems in terms of rolling stability, rolling material defects, and equipment load.

In addition, when existing horizontal rolling mills and vertical rolling mills are alternately arranged, a specific stand is used as a dummy pass to perform rolling in the same direction twice in succession, thereby facilitating the direction of flattening the rolling material. You can change 90 degrees. However,
The reduction rate of the rolled material to be rolled down by the dummy pass stand needs to be transferred to another stand, so that the rolling down schedule needs to be changed.

Further, when a new rolling mill is installed, if the rolling mill is arranged so that the combination of the horizontal reduction pass-horizontal reduction pass or the vertical reduction pass-vertical reduction pass can be continuously performed at least once, the above-mentioned configuration is performed. This eliminates the need for a special dummy path and reduces the distance between stands.

By the above-mentioned method, it is possible to flatten the rolled material of the clad wire rod consisting of the inner layer portion and the outer layer portion in both directions of two directions orthogonal to each other. It is necessary to give the same degree of flatness to. In the final process of continuous rolling of wire rod material, a light reduction of 5% or less is applied to improve dimensional accuracy. However, at this reduction, only the dimensions of the surface layer change and the metal flow inside the material is reduced. Can't bring up. In the present invention, since the main object is a flat shape that gives a certain reduction or higher that causes metal flow, 5% in the reduction direction,
Considering the case where a dimensional change of 5% occurs in the width direction, 1.
The number of passes that gives a flattened shape ratio of more than 1 times is approximately equal between the rolling passes in the two directions.

The reasons for limiting "above 1.1 times" are as follows. That is, in a certain pass, when a material having a length × width of 1 × 1 is pressed down by 5% in the lengthwise direction, and as a result, a width spread of 5% occurs in the widthwise direction, the aspect ratio becomes 0.95 × 1.05. Therefore, the flat shape ratio becomes 1.05 / 0.95 = 1.105, and the flat shape ratio exceeds 1.1 times.

Also. The technical meaning of setting the above-mentioned "pass counts to be approximately equal" is as follows. That is, the present invention is based on the idea that the internal metal flow is made uniform by applying the same degree of reduction in the length and width of the material.
Therefore, ideally, the ratio of the width to the thickness of the material to be rolled on the exit side of the reduction pass (BD / AC in Fig. 5) is a flat shape that exceeds 1.1 times (a horizontal pass), and The most uniform metal flow is obtained when the number of both passes of the flat shape (longitudinal pass) in which the ratio of the thickness to the width of the material (AC / BD in Fig. 5) exceeds 1.1 times is completely the same. To be However, it is possible that the number of both passes cannot be the same depending on the number of rolling stands, the arrangement of the stands, or the required number of passes determined from the required reduction amount. However, as shown in FIG. 5 or FIG. 6, in the process of repeatedly rolling 20 or more passes, even if the number of vertically long passes and the number of horizontally long passes are not completely the same, the metal flow is uniform. It doesn't make it worse.
The point is that the present invention focuses on making the flattening directions substantially the same number of times in the vertical and horizontal directions instead of flattening them in the same direction as in the conventional case.

[Example] (Example 1) Fig. 6 shows a flat shape on the exit side of each pass of a rolled material (cladding material) according to a conventional method. As for the flat shape, assuming that the rolled material does not twist, the horizontal and vertical dimensions of the material on the exit side of each pass were taken, and the flatness was indicated by the ratio (flatness) of the former and the latter. Square-diamond rolling, 7-
Round-oval rolling is performed on the intermediate stand row of No. 18 and the finishing stand row of Nos. 19 to 28.

FIG. 5 shows the flat shape on the delivery side of each pass of the rolled material (cladding material) according to the method of the present invention. In the rough stand row, because there is enough mill motor power, diamond-to-diamond rolling is performed without inserting a dummy path to flatten alternately in each direction. Further, in the middle to finishing stand rows, the flattening direction was changed by inserting a dummy pass once each. The reduction rate that should be shared by these dummy passes was covered by using up to 28 stands that are not normally used.

In FIG. 5 and FIG. 6 described above, a 145 mm square billet was used for rolling, and 24 passes (4 dummy passes) were rolled to a diameter of 15 mm. Inner layer of rolled material is TK-15, outer layer is SF
It was confirmed in advance that the inner layer part consisting of 45 AY and having a 145 mm square billet stage had a diameter of 80 mm and was close to a substantially circular shape.
The continuous rolling was carried out with the goal of no tension, but there is a possibility that the influence of tension fluctuations may be observed at the front and rear ends, so samples were taken from the center in the longitudinal direction after rolling. The above TK
The components of −15 are C 0.16%, Si 0.25%, Mn 0.51%, P 0.01
8%, S 0.010%, Al 0.001%, SF45AY contains C
0.31%, Si 0.30%, Mn 1.05%, P 0.015%, S 0.007
%, Al 0.035%.

Example 2 Next, FIG. 4 (B) shows a C cross section of a rolled material (clad material) rolled by the conventional method, and FIG. 4 (A) shows a rolled material (rolled material rolled by the method of the present invention ( C of clad material)
3 shows a cross section. The shape of the inner layer portion after rolling by the conventional method in FIG. 4 (B) is flat and extends in the oval direction of the last path, and the ratio of the maximum diameter to the minimum diameter of the inner layer portion is 1.35. On the other hand, the shape of the inner layer portion after rolling according to the method of the present invention in FIG. 4 (A) is close to a nearly perfect circle, and the ratio of the maximum diameter to the minimum diameter is 1.06. (Uniformization) is clearly recognized.

(Example 3) Further, FIG. 8 shows [inner layer radius / outer layer radius] in the circumferential direction of the rolled material (cladding material) obtained by the conventional method.
7 shows the change in [inner layer radius / outer layer radius] in the circumferential direction of the rolled material (cladding material) obtained by the method of the present invention. FIG. 9 is a schematic diagram showing the inner layer radius and the outer layer radius of the rolled material. According to FIGS. 7 and 8, it is recognized that the shape of the inner layer portion is rounded by the method of the present invention.

[Effect of the Invention] As described above, according to the present invention, in the clad wire rod rolling comprising the inner layer portion and the outer layer portion, the rolled material is flattened in two directions orthogonal to each other. The strain in the inner layer of the rolled material can be made uniform.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a rolling method according to the present invention, FIG. 2 is a schematic diagram showing a conventional rolling method, FIG. 3 is an end view showing a clad material, and FIG. 4 (A) is a method of the present invention. Fig. 4 (B) is a sectional view showing the clad material rolled by the conventional method, and Fig. 5 is a diagram showing the flatness on the exit side of each pass according to the method of the present invention. FIG. 6 is a diagram showing the flatness on the exit side of each pass according to the conventional method, FIG. 7 is a diagram showing the circumferential shape of the clad material according to the method of the present invention, and FIG. 8 is a diagram showing the clad material according to the conventional method. A diagram showing the shape in the circumferential direction, FIG. 9 is a schematic diagram showing the inner layer radius and outer layer radius of the clad material, FIG. 10 is a schematic diagram showing the hole rolling method, and FIG.
FIG. 12 is a schematic diagram showing a channel rolling method, and FIG. 12 is a schematic diagram showing a channel rolling method.

Claims (1)

(57) [Claims] 1. A method of rolling a clad wire rod comprising an inner layer portion and an outer layer portion in a plurality of passes in each of two directions orthogonal to each other. The ratio of width to thickness of rolled material is 1.
A clad wire rod characterized in that the number of times of reduction passes that result in a flat shape exceeding 1 time and the number of times of reduction passes that result in a flat shape in which the thickness-to-width ratio of the material to be rolled exceeds 1.1 times are approximately equal. Method for rolling a strip.