JPS58125301A - Rolling method of bar and wire rod - Google Patents

Abstract

PURPOSE:To make the holding of materials sure and to form products which are free from generation of flaws and have excellent surface characteristics in the stage of roling square or round materials and obtaining bar and wire rods by repeating substantially flat rolling and caliber rolling. CONSTITUTION:A square material 1 or a round material 1' is used as a blank, and is first rolled with flat rolls 10, whereby materials 1A, 1'A of which the free surfaces are round and bulged sufficiently are obtained. The materials are rolled with round caliber rolls 20, whereby a round material 2A is obtained. Thereafter, the material is passed successively through passes wherein the rolls 10 and the rolls 20 are disposed alternately, whereby the round blank 25A of the No.25 pass and the oval material 26A of the No.26 pass are obtained. Finally, the material is passed through the No.27 pass and the final product 27A is obtained. Thus the original units of the rolls and the labor for changing the rolls are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling rods or wires (hereinafter referred to as rods or wires in some cases), and particularly to a method for rolling rods or wires in which a pass schedule is devised.

When rolling rods and wire rods, selecting a pass schedule is extremely important from the perspective of preventing surface defects, as well as the design of the groove itself. In the same figure shown in FIG. 1, only changes in shape are shown, ignoring changes in cross-sectional dimensions. The material is provided, for example, as a square or round material with a diameter of 125 mm. For this, Nnl −! by the square diamond method. '! The rough row of t8, 19 to N [Li2 is the square oval method, the relationship between -15 and depression 16 is the intermediate row by the round-oval method, and the finishing row of 17 to %22 is prepared by the round-oval method. nru. By arranging the grooved rolls in this manner, a round bar wire having a predetermined shape is obtained.

Other pass schedules include the box-oval method and the less effective diamond-diamond method.

In any case, the conventional method basically uses grooved rolls in all passes.

However, when rolling the oval material 50 with the round hole-type holes 51, 51, as shown in FIG. 2, for example,
The oval material 50 tends to fall over from the top and bottom (indicated by reference numeral 50') particularly at the entrance of the hole, and when this happens, the rolled material 52 has protruding parts 52a, 52.
a occurs, and when it is brought to the next oval hole type roll, it buckles and is compressed, resulting in leaving flaws on the surface of n1. In addition, by the square oval method shown in FIGS.
1, there is a problem in that a gap 62 is formed between the innermost part of the hole of the roll 61 and the end surface 60a of the oval material 60, and seam flaws occur in a portion corresponding to the rolling rear end surface 60a. In order to prevent the occurrence of these defects, various proposals and attempts have been made to use deformed hole shapes instead of simple hole shapes, but no fundamental solution has been achieved.

Another major problem is the increase in roll consumption of grooved rolls. Generally, the seven-flange gap of a grooved roll is small, and if the groove is worn, the flanges of the rolls will come into contact with each other, making it impossible to continue rolling.If the flange gap is provided with a margin, seam defects as described above will occur. Furthermore, when modifying the roll, the amount of modification to the roll must be increased relative to the depth of wear, resulting in a significant consumption of cutting tools. Then, if a certain groove becomes worn out and becomes unusable, it becomes necessary to change the roll even if another groove on the same roll is still usable.

In addition, as shown in Figure 5, multiple holes are usually machined in a 10-hole, but a minimum flange length F is required between the holes to prevent interference and damage. There is a limit to the number of holes per barrel length, and the entire roll barrel length cannot be used effectively. Moreover, as mentioned above, in anticipation of the wear and the amount of modification of the groove, rolls are usually manufactured with a considerable amount of initial roll, so the depth of the groove is at least equal to that of the flat roll according to the present invention, which will be described later. Large diameter rolls are required.

For the above reasons, the roll consumption rate has been forced to increase.

For these methods, the so-called flat rolling method described in Japanese Patent Publication No. 54-37582 is known. According to this method, at least various problems associated with roll wear can be solved. However, when the present inventors actually tried rolling by applying this method, the results shown in FIG. 10 were obtained.

In the figure, (a) shows the cross-sectional shape of rolled iron, and (b) shows the cross-sectional shape of rolled lead. Also, before the final pass, an oval hole type pass is used. As can be seen from Figure 10, it is not very noticeable in the case of iron (Figure (a)), but it becomes clear in the case of lead (Figure (b)), which is normally a regular rectangular cross section. However, it actually shows a collapsed parallelogram shape.

Even if a round bar is obtained using this method, not only will it not be possible to obtain a regular round bar, but if guides 71 and 71 are provided to hold the material 70 as shown in FIG. If the material 70 falls over as shown in the figure, part of the corner of the material 70 will scrape the guide surface of the guide 71, leaving scratches on the product. Therefore, it has not been put into practical use.

The present invention has been proposed to address the problems of the prior art.
The purpose is to provide a rolling method that can improve the stability of material retention, prevent the occurrence of scratches, and obtain beautiful surface textures, with the main purpose being to reduce the roll consumption rate. 0 To achieve this objective, the present invention provides a method for rolling a bar or wire rod to obtain a rolled product of a desired size from a raw material.
In other words, the present invention is configured to perform rolling with a pass schedule in which flat rolling and groove rolling are alternately repeated for most of the passes.
Not due to flat-flat rolling, but substantially
This is done by flat single-hole rolling.

FIG. 7 shows a specific example of the present invention. The material used is a square material 1 or a round material 1', but other shapes may be used if necessary. First, for this material, Rolling is performed using flat rolls 10, 10. As a result, the pressing blade penetrates into the inside, and the free surface is rounded and fully protrudes. Therefore, since rolling is carried out without strain, surface flaws do not occur. Here, compared to the oval-shaped material IA obtained when the square material 1 is used as the material, the material 1'A obtained when the round material 1' is used has a more rounded free surface. It tends to be large. Then, in the N12 pass, the material is rolled by round hole type rolls 20°20 to obtain two round materials. After that, while sequentially passing the alternately arranged passes of flat rolls 10, 10 and 2 and land hole type rolls 20 and 20, the round material 25A of N1125 pass is followed by the %26 pass of the bud-pal material 26At=4*after , finally N1
The final product 27A is obtained through 27 passes.

Here, when the flat material 1a is rolled by the round hole die 20a, the cross-sectional shape changes as shown in FIG. At this time, the free surface of the flat material 1a has a roundness similar to that of the round hole shape in the previous pass, so even if it is rolled upwards and downwards, the free surface maintains the hole shape stably. The occurrence of scratches caused by falling, falling, and the like is prevented.

Regarding the self-retention of the material due to the groove shape, on the one hand, by selecting the axial dimension ratio during flat rolling,
On the other hand, by selecting the round hole shape, the optimum design can be achieved.Incidentally, the shaft dimension ratio b/
a is preferably 1.7 to 2.7, particularly preferably 2.0 to 2.5.

In addition, when rolling was actually performed using the method of the present invention,
The cross-sectional shape shown in FIG. 11 was obtained, and not only was the shape free from distortion in each pass, but also no defects were observed in the obtained product.

By the way, in the above example ', the reason why flat rolling was not performed in the pass before the final pass and an oval hole type was used was to improve the roundness. However, it is not impossible even by flat rolling.

On the other hand, the reason why a round hole type was used as the child mold in the above example is because, for example, an oval hole type has some difficulty in stably holding the material, but it is not necessarily limited to a round hole type. By using a flat roll as in the method of the present invention, not only can smooth rolling be achieved without the occurrence of defects, but the amount of modification relative to the amount of wear can be reduced compared to the case of a groove type. Since only a small amount is required, long-term use is possible without changing rolls.Furthermore, in flat rolling, the J-roll gap is equal to the material thickness on the exit side of the rolls, so the roll diameter can be made small. Furthermore, flat rolls enable adjacent rolling with almost no flange portion, as shown in FIG. 9, so that the length of the roll barrel can be utilized to the maximum extent possible. Therefore, the roll consumption rate can be reduced. The roll consumption rate is expressed as n.

In the conventional method, the roll consumption rate is 0.15 to 0.2 kg/l
However, when the method of the present invention is used, the number of passes is reduced by about 20 times, which corresponds to the number of passes in place of the flat roll.

As described above, since the present invention uses flat rolling and single-hole rolling in combination, it is possible to reduce the roll consumption and the time and effort required to change rolls, and the material is reliably held and the surface is free from scratches. There are advantages such as being able to obtain a product with excellent properties.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional shape change diagram showing an example of a conventional bus and schedule; Fig. 2 is a diagram of overturning and bite occurrence in oval-round hole rolling; Fig. 3 is a diagram of the positional relationship of rolls; Fig. 4 Fig. 3 shows the state of oval-square rolling while showing the groove shapes corresponding to the positions ■ and ■, Fig. 5 shows an example of the flange portion, and Fig. 6 shows the flat-square rolling.
FIG. 7 is an explanatory diagram showing an example of a pass schedule according to the present invention; FIG. 8 is a diagram of the state during round rolling of a flat material; FIG. 9 is an example of adjacent flat rolling. Figure 10 (&), (b) are flat-
FIG. 11 is a diagram illustrating an example of cross-sectional change in the case of flat rolling. l, 1'...Material IA~27A, 1'A...Material 10
...Fran Troll 20...Round hole roll No. 1, Fig. 2, Fig. 4, Fig. 5, Fig. Ajie 8 Uta ■ o & 8 Ki & Ki, ~

Claims (1)

[Claims] (1) A method for rolling a bar or wire rod to obtain a rolled product of a desired size from a raw material, characterized by rolling with a pass schedule consisting of alternating flat rolling and slotted rolling for most of the passes. Rolling method for rods and wire rods 0