JPS594905A - Production of hollow bar material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing a hollow bar. Note that the term "hollow bar" herein refers collectively to ultra-thick hollow bar-like bodies produced in general steel bar rolling mills. To give an example of the dimensions, the wall thickness/outer diameter ratio (hereinafter simply referred to as T/D) is 26 to 306 or more (outer diameter itself is This type of hollow rod is conventionally manufactured by the following process as shown in Figure 6. My friend. FIG. 6 is a schematic diagram showing the conventional manufacturing process for hollow bars. First, as shown in FIG. A hole is made in the center of this square billet B2 using a tri/l/32 as shown in Fig. 6(b) to form a square hollow material B3, and then manganese is inserted into this as shown in Fig. 6(b). A steel core bar 33 is inserted and heated in this state to a required temperature in a heating furnace 34 as shown in Fig. 6).
The hollow material B3 is finished by passing it through a continuous steel bar rolling machine [35] consisting of more than 10 stand rows, so that its outer diameter and wall thickness match the target values, and the core bar 3 is rolled as shown in FIG.
3 and cut it to a regular length, then Fig. 6 (G)
As shown in Figure 1, curve 9 straightening is performed in straightening 11136 to obtain a hollow bar B4 as a finished product. However, such conventional manufacturing methods have the following problems. That is, (1) Rolling is carried out with the core metal 33 running through the inner surface regulating tool inserted into the hollow material B3, but since the core metal 33 itself is also plastically deformed, the roundness of the finished product is poor and uneven thickness is avoided. (2) There is a large variation in the inner diameter, which naturally results in variation in the wall thickness, and the overall dimensional accuracy is low; (3) The core metal 33 is plastically deformed and is therefore disposable. The cost is high and uneconomical, etc. Among the problems with such conventional methods, a method for manufacturing hollow bars such as the conventional method has been proposed in an attempt to solve the drawback that the tool consumption rate is high due to the use of a cored metal. That is, first, a press piercing mill is used to perforate the bloom, and then this hollow material is passed through a continuous rolling mill in which oval round hole rolls are arranged horizontally and vertically alternately, without using a core bar as an inner surface regulating tool. This is a method of rolling (Japanese Patent Application Laid-Open No. 114407/1986).

However, according to experiments conducted by the present inventors, it has been confirmed that it is extremely difficult to ensure sufficient roundness using the two-roll type rolling mill row using slotted rolls. In addition, in a three-way roll type rolling mill row using the same hole type row p, the roundness is better compared to a two-roll type rolling mill row, but
It was also confirmed that there are certain limits to this.

The present invention was made in view of the above circumstances, and its purpose is to reduce both the outer diameter and wall thickness of a hollow material using an inclined rolling mill having three or four cone-shaped rolls. To provide a method for manufacturing a hollow bar that does not require the use of an inner surface regulating tool and can significantly improve dimensional accuracy in both outer diameter and wall thickness by performing elongation rolling.

The method for producing a hollow bar according to the present invention is to produce a hollow material obtained by drilling a round bar by machining or plastic processing to a target finished outer diameter without using an inner surface regulating tool such as a plug or a mandrel. , the intersection angle and inclination angle were adjusted according to the wall thickness 3
It is characterized by including a ground rolling process in which the material is passed through a cross-type inclined rolling mill having one or four cone-shaped rolls, and the outer diameter and wall thickness are reduced to the respective target values.

Although the technical content of the present invention is completely different from that of the present invention as described above, it is related to an invention by one of the inventors of the present invention as a method in which the processing target areas are close to each other, and has already been proposed by the present applicant. There is a method for manufacturing seamless pipes for which an application has been filed (patent application filed in 1973).
6-22540), we will touch on the basic technical differences between this method and the method of the present invention. The gist of the invention of this previously filed application is that three or four four wheels are arranged facing around the pass line, and the axis lines thereof are inclined so that the shaft ends on the same side face the same side in the circumferential direction. By using a cross-type inclined rolling mill, in which the shaft ends on the same side can be inclined (crossed) so as to approach or move away from the pass line side, the blank tube can be rolled without using an inner surface regulating tool. A method of manufacturing a seamless metal pipe is characterized in that it includes a step of applying a drawing process to the outer diameter.

In other words, when the outer diameter of the raw pipe is reduced to increase its wall thickness, if there is uneven thickness in the raw pipe, the rate of increase in wall thickness is greater in the thinner parts than in the thicker parts. However, according to the experiments of the present inventors, the range in which the above-mentioned correction effect can be obtained is T/D.
is within the range of 26 to 30 -, and beyond this range, it is physically impossible to increase the wall thickness by drawing the outer diameter even if the conventional sheet metal technology 11 is applied. It is confirmed that it is good. This means that the applied technology of the existing application is naturally applicable to T/D = 25 to 30 liters or less. On the other hand, the present invention is applicable to T/I), which can reduce both the outer diameter and wall thickness! 5～
The method of the present invention applies not only the outer diameter but also the wall thickness. Since the so-called stretching and rolling process is applied to reduce this, it can be seen that the technical contents of the two are completely different.0 The present invention will be specifically explained below based on drawings showing its implementation state. . FIG. 1 shows a method for manufacturing a hollow bar according to the present invention (
1 (hereinafter referred to as the method of the present invention) in the order of its steps, first, a round bar material A (
Prepare a round steel piece (which may be a round piece of steel) and drill it by machining using a drill 1 as shown in Fig. 1 (b) to form a hollow material A2. The round bar material A is heated to a required temperature as shown in (c), and then stretched and rolled using an inclined rolling mill 4 as shown in (c) of the first FA.
First, the round bar material s is heated in a heating furnace 2 to a required temperature suitable for plastic working as shown in FIG. A hole is formed in the center using a hollow material A2, and the hole shown in Figure 1 above is formed.
As shown in FIG. 2, the product is stretched and rolled using an inclined rolling mill 4 and then cut into regular lengths to obtain a hollow bar A3. Inclined rolling mill 4 is shown in figure g2 (
It is constructed as shown in (a), (b), and (b).

FIG. 2 P) is a schematic front view seen from the entrance side of the hollow material A2 showing the state in which the hollow material A2 is being stretched and rolled in the inclined rolling mill 4;
FIG. 2(b) is a cross-sectional view taken along the Rolo line in FIG. 2(a), and FIG. 2(c) is a side view taken along the Haber line in FIG. 2(a). l:ts I:l- Each A/4t has a gorge part 41a near one end in the axial direction, and the diameter is gradually reduced toward the axial end on the one end side in the axial direction with this gorge part 41 as a border, and the diameter is gradually reduced toward the axial end. is configured as a cone having an inlet surface 41b and an outlet surface 410 each having a truncated cone shape whose diameter is gradually enlarged toward the shaft end. Each row/I/41 is in a state where its entrance surface 41b side is located upstream in the moving direction of the hollow material A2, and at the intersection of the axis Y-Y and the plane containing the gorge portion 41L, respectively. O (hereinafter referred to as the roll setting center) is located on the same plane orthogonal to the pass line XX of the hollow material A2, and the shaft portions 41d are arranged at approximately equal intervals around the pass line XX and are located at both ends. , 41e is supported by a bearing (not shown), and its axis Y-Y is centered on the setting center O, and the hollow material A2
In relation to the pass line X-X, the required angle γ (hereinafter referred to as the intersection angle ), and as shown in Fig. 2 C → in side view, the front shaft end is inclined by a required angle β (hereinafter referred to as the inclination angle) toward the same side in the circumferential direction of the hollow material A2. It is placed under strict conditions.

Each row/L' 41 is connected to a drive source (not shown) and rotated in the direction of the arrow as shown in FIG. ! While being rotationally driven by the transverse axis 9 and moved in the pass line direction, so-called spiral movement, the material is elongated and rolled under high pressure while reducing the outer diameter and wall thickness at the same time. Figure 3 (a),
(B) and (C) show another configuration of the elongation rolling process used in the present invention and the inclined rolling mill used therein], and FIG. 3 (A) is a schematic front view thereof as seen from the exit side of the rolling mill. , FIG. 3(b) is a schematic cross-sectional view taken along the Rollo line in FIG. 3(a), and FIG. 3(c) is a schematic side view taken along the Haber line in FIG. 3(b). Both indicate rolling rolls.

The configuration of the Low/l151 itself is shown in Figure 2 (A) and (
B).

(c) It is substantially the same as the embodiment shown in K, but the attitude of the hollow material 2 with respect to the direction of movement is opposite. That is, each row/I/61 has a gorge portion 41& near one end in the axial direction, and the diameter is gradually reduced toward the axial end on the circumferential side of the gorge portion 51a. The other end side is configured as a cone having an exit surface 51S and an entrance surface 51b having a truncated cone shape whose diameter is gradually enlarged toward the shaft end.

Each roll 51 has its entrance surface 5ib side positioned upstream in the moving direction of the hollow material A2, and the row setting center O is positioned on the same plane orthogonal to the pass line XX of the hollow material A2. and are arranged at approximately equal intervals around the pass line XX. And the axis Y- of each row A151
Y is centered on the setting center O, and the intersection angle γ is set so that the rear end is separated from the pass line X-X in plan view as shown in Figure 3 (b), The shaft ends are arranged so as to be inclined by an inclination angle β toward the same side of the hollow material A2 in the same direction.

Note that the intersection angle r of the row/L'51 of the inclined rolling mill shown in Fig. 3 (a), (b), and (c) is the pass line X-X of the hollow material A2, as is clear from Fig. 2 (b). Since the angle with respect to the pass line XX of the hollow material A2 shown in FIG.
〉O), and the latter case is taken as negative (γ 0).

The above-mentioned intersecting angle and inclination angle have a close relationship with the inner diameter of the hollow bar that is the product.If the relationship between the intersecting angle and inclination angle and the inner diameter is determined in advance and the setting is controlled appropriately according to the target value, good. There are no particular limitations on the means for setting the crossing angle and inclination angle, and the configurations conventionally used may be used.
Alternatively, appropriate improvements may be made to increase the setting range. An example of the relationship between the cross angle, the inclination angle, and the hole diameter is shown in FIGS. 4(a), (b), and (c).

Figures 4 (a), (b), and (g) all show the hole diameter (am) of the hollow material before rolling on the horizontal axis, and the hole diameter (IIIm) after rolling on the vertical axis. The intersection angle γ is 9° in Figure 4 (a) and 0 in Figure 4 (b).
For 6% Fig. 4 (c), it was set to -9°, while the inclination angle was changed in six steps: 8', 56, 7°, 9°, 11'', and 18°. Inclined rolling mill The rolls were all of the 80mm type with a cone roll, the roll material was 80M, and the gorge diameter was 205mm.The test material used was 8450 carbon steel. , diameter 7
0 mrnb length 800 pieces are used, and each of these is
Diameter 8+nm 510mm in the center, 1211111%14
mm, 16 mm to 118 mm holes are machined to create a hollow material, and the intersecting angle and inclination angle are adjusted according to the predetermined target outer diameter and wall thickness without using inner surface regulating workers such as core metal. was elongated and rolled at a heating temperature of 1200° C. in a controlled 80-mill cross-y, yoke-type inclined rolling mill, and the hole diameters before and after rolling were detected.

As is clear from this graph, when comparing the hollow material and the rolled material in °C, both the outer diameter and wall thickness have been reduced, and the intersection angles are at their values r-9°, 0', - 9
Although the effect of reducing the pore size can be seen in both degrees,
The reduction effect is maximum at f-9°, and the hole diameter changes even when the inclination angle is changed while keeping the intersecting angle constant. It is understood that the pore diameter can be controlled by controlling the settings.

Next, the results of a comparative test between the method of the present invention and the conventional method will be explained.

Here, the method of the present invention is shown in Figure 2 (a).
As shown in (b) and (c), a method of manufacturing a hollow bar by elongation rolling using an 80 mm cross-type inclined rolling mill is used. A hole is drilled into the hollow material, a manganese steel core is charged into the hollow material, and this is rolled by a continuous steel bar rolling mill with oval round hole type rolls arranged horizontally and vertically alternately. A method of obtaining bar stock was used.

The hollow material used was one with an outer diameter of 110 mm+ and an inner diameter of 80 mm+, and this was rolled with an outer diameter of 88 mm as the target value.
The outer diameter, inner diameter, roundness, and uneven thickness of the hollow bar after rolling were detected. The results are shown in Table 1. The cross section of the hollow bar obtained by the method of the present invention is shown in Figure 145 (A), and the cross section of the hollow bar obtained by the conventional method is shown in Figure 2 (B).

Table 1 As is clear from Table 1 and Figures 5 (a) and (b), when the method of the present invention is used, both the outer diameter and wall thickness are dramatically improved compared to the conventional method. I understand.

As described above, in the method of the present invention, the intersecting angle of the hollow material is adjusted according to the target value without using an inner surface regulating device.

Stretch rolling is performed in an inclined rolling mill with 8 or 4 cone-shaped rolls with adjusted inclination angles to reduce both the outer diameter and wall thickness, resulting in less variation in outer diameter and wall thickness, resulting in a finished product. The dimensional accuracy has been significantly improved, and the tool consumption is low because no inner surface regulating tool is used.
The present invention has excellent effects, such as being able to control the inner diameter over a wide range by manipulating the inclination angle, and the overall equipment cost being low.

In addition, although the above-mentioned embodiment is a case in which the housing is fixed and the material rotates, the same effect can be obtained by applying it to a structure in which the housing rotates and the material does not rotate. That's what you get.

[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 schematic front view of an inclined rolling mill used for carrying out the method of the present invention, Figure 2 (Hd) is a schematic sectional view taken along the row line of Figure 2 (A), and Figure 2 (C) is a ζ 32 (o) is a schematic side view taken from the harbor line, No. 8 n 8(a) is a schematic sectional view taken along the line a, FIG. 8(c) is a schematic side view taken along the harbor line of FIG. 8(b), and FIGS. c) is a graph showing the relationship between the intersection angle, inclination angle, and the hole diameter of the hollow bar;
b) is a cross-sectional view of a hollow bar obtained by the method of the present invention;
Figure (b) is a cross-sectional view of a hollow bar obtained by the conventional method.
FIG. 6 is a schematic diagram showing the conventional method in the order of its steps. 1... Drill 2... Heating furnace 8... Extruder 4.
... Inclined rolling mill 41 ... Roll 41a ... Gorge part 41b ... Inlet surface 410 ... Outlet surface 51
...Roll 51a...Gorge portion 510...Entrance surface 510...Exit surface Patent applicant: Sumitomo Metal Industries, Ltd. Patent attorney Noboru Kono (0') (d) Tail 1 Figure (c) 'nno1j (Hon whistle Figure 4 (A) Whistle 4 Figure (B)

Claims (1)

[Claims] 1. The intersecting angle and inclination angle can be adjusted according to the target finished outer diameter and wall thickness of the hollow material obtained by machining or plastic processing multiple holes on a round bar material without using an inner surface regulating tool. Production of a hollow bar, characterized by including an elongation rolling process in which the bar is passed through a cross-type inclined rolling mill having three or four cone-shaped rolls to reduce both its outer diameter and wall thickness to a target value. Method.