JPS59225802A - Manufacture of metallic material having circular cross section - Google Patents

Abstract

PURPOSE:To make an installation, for rolling a metallic material having circular cross section, small in size and to improve the quality of products by using alternately the surfaces of both sides of the maximum diametral part of a barrel-type roll of skew mill for the purpose of skew-rolling a round bar material reversibly. CONSTITUTION:In a skew rolling mill for obtaining a metallic material having circular corss section by rolling a round bar material A1 heated to a prescribed temperature by a heating furnace, etc. with the aids of 3-4 skew rolls 21- installed around a pass line X-X; said skew roll 21 is formed into a barrel-type consisting of the reeling roll surfaces 21d, 21e whose diameters are gradually decreased to both sides of an edge part 21a with maximum diameter, located at the central part of an axial center line, and working roll surfaces 21b, 21c. Each of said rolls 21- revolved around the axial center line Y-Y, and the material A1 is first rolled at the side of working roll surface 21b and next, the material A1 is passed from the opposite side, to roll it at the side of working roll surface 21c by changing the inclination of roll 21, in order to obtain a metallic material having a circular cross section of prescribed shape by repeating said rollings alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a circular cross-section metal material such as a round steel bar using an inclined rolling mill.

Round steel bars are generally manufactured through a rolling process using caliber rolls, but methods using inclined rolling mills have been attempted for the purpose of reducing equipment costs.
The inclined roll rolling mill disclosed in Japanese Patent No. -43980 is famous as a high-workability rolling mill that can reduce a solid +4 to a high degree in one pass. The inventors of the present invention have already filed an application for an inclined rolling method that enables a reduction in area of 80 to 90% per pass and also enables high-deformation rolling that does not cause so-called Mannesmann fracture, which causes brittleness in the center. (Japanese Patent Application No. 57-114362). By the way, when manufacturing bars, for example, there is a limit to the size range that can be manufactured with an area reduction rate of about 80 to 90%, and an even larger area reduction rate is often required. If you try to do this, the rolling mill itself will become significantly larger and the equipment cost will increase, so usually multiple rolling mills are installed to perform rolling, but this method reduces the running cost.
There were also drawbacks such as high production efficiency and low production efficiency. Especially when dealing with difficult-to-process materials such as high alloys and titanium alloys, which have been developed in recent years, there are certain restrictions on the area reduction rate, so it is not possible to process them in one bath, and rolling is performed in several baths. However, since it takes a considerable amount of time to perform several baths of rolling using an inclined rolling mill, there are problems such as extremely difficult temperature control during this time.

The present invention has been made in view of the above circumstances, and its object is to include a so-called barrel-shaped roll having a maximum diameter part in the middle part and gradually decreasing in diameter from there toward both ends. A circular cross-section metal material capable of reducing the size of equipment and improving product quality by enabling reversible inclined rolling by alternately using the roll surfaces on both sides of the maximum diameter part of the roll in an inclined rolling mill. To provide a manufacturing method.

The method for producing a circular cross-section metal material according to the present invention uses an inclined rolling mill having a barrel-shaped roll having a maximum diameter part in the middle part and whose diameter is gradually reduced from there toward both ends. It is characterized by including a T culm that undergoes reversible rolling.

The method of the present invention will be specifically explained below based on the drawings showing its implementation state.

FIG. 1 is a schematic diagram showing the method of the present invention in the order of its steps,
First, as shown in Figure 1 (a), a round bar material Al having the required diameter is
(a round piece of steel may be used) is heated in a heating furnace 1 as shown in Fig. 1 (b).
After heating to the required temperature in the incline rolling mill 2, as shown in FIG. Switch the corner and roll the round bar A1 in the opposite direction, and if necessary, reheat it in the heating furnace 1 and repeat the rolling to achieve the required method specifications as shown in Figure 1 (E). A straightening machine 3 is used to straighten the bend, and a cutting machine 4 is used to cut the bar to a specified length to obtain a product bar A2, as shown in FIG. Heating furnace except for inclined rolling mill 2! , the straightening machine 3 and the cutting machine 4 are conventionally known per se. The inclined rolling mill 2 is constructed as shown in FIGS. 2(a), 2(b), and 2(c).

FIG. 2(A) is a schematic front view of the round bar A5 seen from the entry side showing the state in which the round bar A1 is being stretched and rolled in the inclined rolling mill 2, and FIG. FIG. 2(A) is a cross-sectional view taken along the Rollo line, and FIG. 2(C) is a side view taken along the Haver line in FIG. 2(A). It is provided with three (or four) inclined rolls (hereinafter simply referred to as rolls) 21, 21.21 arranged around the periphery. Each roll 21 has the same shape, and has a gorge portion 21a having the maximum diameter at the center of the axis, and a gorge portion 21a having the maximum diameter at one end in the axial direction with this gorge portion 21a as a boundary. The reeling roll surfaces 21d, 21e are generally truncated conical reeling roll surfaces 21d, 21e that are gradually reduced linearly or curved, and the working roll surfaces 21b, 21. It is equipped with c.

Each roll 21 is initially positioned with its working roll surface 2Ib side located upstream in the moving direction of the round bar A1, and at the intersection O( (hereinafter referred to as the roll setting center) are positioned on the same plane orthogonal to the pass line XX of the round bar A1, and are arranged at approximately equal intervals around the pass line XX, and the shaft portions 21f at both ends, 21g is supported by a bearing (not shown) and is driven to rotate around the axis Y-Y. The pass line XX of the round bar A1 and the axial center line Y=Y of the roll are as shown in FIG. They intersect at a required angle γ (hereinafter referred to as intersecting angle) so that they approach toward the round bar A1, and when viewed from the side, as shown in FIG. Required angle β toward the side
(hereinafter referred to as the inclination angle).

Each roll 21 is driven by a drive source (not shown) as shown in FIG.
As shown in b), the round bar /'z caught between these is driven to rotate in the direction of the arrow, and is rotated in the direction of its axis, while being moved in the direction of the pass line, so-called spiral movement. They are now being subjected to high-strength elongation rolling, which reduces the diameter while being processed.

Then, without pulling out the round bar Al from the rolls 21, each roll 21 is set as shown in FIGS. In this case, the rolling stock is sent toward the inclined rolling mill 2 from the opposite direction to the case in c). FIG. 3(a) is a schematic front view of the round bar material A1 seen from the entrance side without showing the state during reverse elongation rolling by the inclined rolling mill 2, and FIG. A) is a sectional view taken along the Rollo line, and FIG. 3C is a side view taken along the Haver line of FIG. , with the working roll surface 21b positioned on the downstream side, the pass line X-X of the round bar A+ and the axis Y-Y of the roll are as shown in FIG. 3 (b) in plan view. The front end, that is, the shaft end on the side of the working roll surface 2Ic is crossed by a crossing angle γ so that it approaches the pass line XX, and when viewed from the side, the working roll surface 2Ic is crossed as shown in FIG. 3(c). The shaft end on the 2Ic side is set to be inclined by an inclination angle β toward the same side in the circumferential direction of the round bar /'z.

Each roll 21 is driven to rotate in the direction of the arrow by a drive source (not shown), and is driven to rotate between the axes of the round bar Al inserted between these l''-rolls 21, while While moving the material in the longitudinal direction, it is subjected to elongation rolling to reduce the outer diameter with a high degree of processing while moving the material in a vertical direction.

The above-mentioned intersection angle γ and inclination angle β are both as follows (1)
It is set so as to satisfy the conditions of formula (3).

0 degree This is because if the end of the roll shaft located on the downstream side in the direction of movement approaches the pass line XX, shear stress will be concentrated at the center of the cross section, causing Mannesmann fracture. The reason why the lower limit of the inclination angle β is set to 3° is due to the structural reason that the drive shaft of the roll interferes with the round bar material when the angle is 10° or more. This is because it is not possible to reduce the shear deformation in the circumferential direction near the center and to obtain a sufficient porosity crimping effect in the continuously cast rolled material, and this is also the reason why the upper limit of β was set to 20°. The above is the structural reason for interference between the roll end face and the part closest to the pass line of the roll chock on the downstream side in the moving direction of the rolled material.Furthermore, the lower limit value of γ + β was set to 5°. However, it is not possible to ensure practical rolling efficiency (speed), and if the angle is less than 30°, the interference between the roll chock and the rolls will increase. This is due to the fact that it becomes difficult to keep the roll in place, and the structure that supports the roll on both sides cannot be maintained.

The above explanation is about a configuration in which the roll shaft ends are rotated in the same direction around the pass line and the rolls are rotated in the opposite direction when viewed from the input side of the rolled material when performing reversible rolling. Of course, it is also possible to adopt a configuration in which the roll shaft end is rotated in the opposite direction around the pass line and the rolls are rotated in the same direction when viewed from the input side of the material.

Next, examples of the method of the present invention will be described using specific numerical values.

Example 1 Diameter made of 545C: 10Qmm, length 7300mm
After heating the x-layer round bar material to 1200°C, the rolls of the inclined rolling mill are rolled in Figure 2 (A), (B), (C), and Figure 3 (A).
, (B) and (C), reversibly make two passes to reduce the outer diameter of the round bar from 100 inches to 55 mm, 55111
-30 fins are stretched and rolled, and the rolled round bar material is heated to 870℃ for 1 hour.
After heat treatment was performed for 45 minutes, a JISJ test piece was taken and its mechanical properties were examined. The cross angle γ of the rolls was 4°, and the inclination angle β was 3°.

5°, 7°, 9°, 11°, 13°, 15°, 17°
It was changed in 8 ways. The dimensions of the roll are shown in Table 1.

The results are shown in Figure 4. The graph shown in Figure 4 shows the inclination angle β on the horizontal axis, and the aperture ratio (%) on the vertical axis.
, elongation rate (%), tensile strength (kg/mm2) in the upper row
, 0.2% proof stress (kg/mm") is shown. The shaded areas in the graph indicate the mechanical properties of fW0 steel bars obtained by a general steel bar rolling mill using cover rolls. As is clear from this graph, the mechanical properties of all cases improve as the angle of inclination increases, and when the angle of inclination exceeds 7°, they are equivalent to or better than those using caliber rolls. On the other hand, it can be seen that when the inclination angle is 3° or less, both the reduction rate and the elongation rate are significantly lower than in the conventional method.

Further, the diameters of the 164 round bars obtained above with an inclination angle of 15° were measured at different positions in 8 directions on the cross section, and the roundness was measured according to the formula below.

The axis shows diameter roundness (%), and the vertical axis shows frequency. As is clear from this graph, the roundness is 0.0
54%, that is, the average outer diameter difference is 0.0211, which shows that extremely highly accurate rolling is performed.

Example 2 1 6A which is a typical titanium alloy 7! -4ν alloy diameter: 89. Fhm, length 30 (ln, composition shown in Table 2) An alloy rod was manufactured, and this was heated to 930°C, and the crossing angle γ was set to 4" and the inclination angle β was set to 15°. The samples were reversibly stretched and rolled according to the bus schedule shown in Table 3 using an inclined rolling mill as shown in Figures 3 and 3.

The roll material is SC old 40 gorge part diameter 200.
1■ was used. The obtained bar material was subjected to ultrasonic flaw detection, specimens were taken from each part, their mechanical properties were examined, and the notch stress loveture test was performed.
(Notch 5tress Rupture test) was conducted. Ultrasonic flaw detection was carried out using a water immersion flaw detector with an output of 5 MHz using a ll5IPII (Cloud Cramer type) flaw detector. The results were good and no defects were detected. On the other hand, the specimens for measuring mechanical properties such as 0.2% proof stress, tensile strength, elongation rate, and reduction ratio were taken from the center of the bar and from a position deviated by a radius of /2 from the center. 6th
A material processed to the dimensional specifications shown in Figure (a) was used, and a material taken from the same site 2 and processed as shown in Figure 6 (a) was used for the notch stress/loveture test. The length of the parallel part of the test piece for tensile tests, etc.: 2
ON, diameter: 4. Om, grip length: 12.5m,
The shoulder radius was 41 and the total length was 520. The test piece for the notch-stress-loveture test is an annular grooved test piece as shown in Figure 6 (B), and the opening angle of the groove is as shown in Figure 6 (B).
c) As shown in <60°±30', ■Groove bottom radius is 0.0
1±0.013 crane, other parallel parts, grip part dimensions, and shoulder radius are as shown.

The test pieces were all heat-treated by being held at 705°C (+10°C to -0°C) for 2 hours and then air-cooled.

In the tensile test, the strain rate is 0.2% and the yield strength is 0.5%.
/min (0.08n+/min), and 1 after 0.2% proof stress
It was set to 2.5%/min (2, On/min). In addition, in the Notsuchi Stress-Labture test, it was 170 Ksi (1
19 kg/*va2). The results are shown in Table 4.

As is clear from Table 4, it was possible to produce an alloy rod that satisfactorily satisfies the AMS4928H standard.

Figure 7 (a), (b), and (c) show the results of the method of the present invention. , I'm in agony 1j constant 91.

Table 4 Microstructure in longitudinal cross section of bar material obtained by xAMS4928HJ inspection,
Photos of the surface, radius/2 area, and center are shown at 500x magnification, respectively.

As is clear from this photograph, a titanium alloy rod having an equiaxed α+β structure could be manufactured.

Furthermore, the β transus (the temperature at which the two phases of α and β become the β-phase) of the titanium alloy rod obtained by the method of the present invention described above was measured and found to be 990°C.

As described above, in the method of the present invention, the inlet face of the roll in an inclined rolling mill equipped with barrel-type rolls.

Since the material is rolled reversibly using both sides of the outlet surface, production efficiency is extremely high, the entire equipment can be made more compact, the dimensional specification range that can be manufactured is wide, the cross section is uniform, and there are no surface defects. The present invention exhibits excellent effects, such as no generation, high machining accuracy especially for difficult-to-process materials such as titanium alloys, and a dramatic improvement in yield.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the method of the present invention in the order of its steps;
Figure (a) is a front view of the inclined rolling mill used for carrying out the method of the present invention, viewed from the material input side, Figure 2 (b) is a schematic sectional view taken along the rolling line of Figure 2 (a), and Figure 2 ( C) is a schematic side view taken from the harbor line of FIG. 2(B), FIG. ) is a schematic cross-sectional view taken by the Rollo line in FIG. 3(A), FIG. 3(C) is a schematic side view taken by the Haber line in FIG. The graph showing the mechanical properties of the obtained round steel, FIG. 5, is the same. The histogram of the outer diameter roundness (%) obtained in Example 1, FIG. Example 2 of the present invention
Figure 7 (a), (b), (
c) 4 years old It is a microstructure photograph of each part in the cross section of the titanium alloy rod obtained in Example 2. A I + A 2...Round bar material 1...Heating furnace 2
... Inclined rolling mill 3 ... Straightening machine 4 ... Cutting machine
21a... Gorge portion 21b... Working roll surface 2IC... Working CCl-roll surface 21d... Reeling roll surface 21e.
...Reeling roll surface 21f, 21g... At the shaft portions at both ends of the roll Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono 7 1 t Sonoki circular layer (Z) Fig. 5

Claims (1)

[Claims] 1. A step of reversibly rolling a material to be rolled using an inclined rolling mill having a barrel-type roll having a maximum diameter part in the middle part and having a diameter gradually reduced from there toward both ends. A method for manufacturing a circular cross-section metal material, the method comprising: 2. Three or four barrel-type rolls are arranged facing around the pass line and have a maximum surface I flea in the middle part, and the diameter is gradually reduced from there toward both ends. An inclined rolling mill is used in which the inclination angle β and crossing angle T of the rolls are set to satisfy 0°≦γ〈10′ 3°〈β〈20゜5°〈γ+β〈30゛ with respect to the moving direction. 1. A method for manufacturing a metal material with a circular cross section, the method comprising the step of reversibly rolling a material to be rolled.