JPS61253102A - Cross helical rolling mill - Google Patents

Abstract

PURPOSE:To improve the accuracy of a diametral size by setting the length in the reeling part of each cone type roll of a cross helical rolling mill by a mathematical expression thereby executing rolling while bringing each part of the axial direction of a rolling material into contact with the reeling part at a prescribed number of times or above. CONSTITUTION:The rolls 1, 2, 3 are rotated in arrow directions and while the rolling material 4 engaged between these rolls is rotated around the axial center thereof at hot, the material is moved in the axial longitudinal direction. The walking size l at the axial length of the reeling parts 1c, 2c, 3c of the rolls 1, 2, 3 is set under the conditions of the equation in such a manner that the respective parts of the material 4 in the longitudinal direction thereof contacts >=7 times in total with the reeling parts 1c, 2c, 3c of the rolls 1, 2, 3 in the process of passing between the rolls 1, 2, 3. In the equation, (d) is the set outside diameter, B is an angle of inclination and (m) is the number of the disposed rolls. The equation is set by determining the number of contacts at >=7 times and may be set by taking production efficiency into consideration as the accuracy of the diametral accuracy is improved up to the specified level but not above the same.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an inclined rolling mill for producing circular cross-section metal materials such as round IF steel and hollow steel bars.

[Prior art]

Round steel bars, hollow steel bars, etc. 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.

Conventionally, the inclined rolling mill used in the 7i method has three or four rolls facing around the pass line, whose axis is
Inclined so that the shaft ends on the same side face the same side in the circumferential direction,
In addition, the shaft ends on the same side can be inclined (crossed) so as to approach or move away from the pass line side, and the inclination angle and crossing angle of the rolls are set so as to satisfy predetermined conditions, respectively. (Japanese Unexamined Patent Publication No. 59-4902).

[Problems with conventional technology]

By the way, in the conventional inclined rolling mill as mentioned above, in the longitudinal direction of the rolled material! l! l! There were problems such as the formation of spiral scratches, which reduced the dimensional accuracy of the finished product.

[Means for solving problems]

The inventors of the present invention conducted experimental research on means for eliminating the spiral scratches as described above, and found that there is a close relationship with the reeling length of each cone type roll, and that the reeling length is a certain length or more. Then, in the process of the rolled material passing between the rolls of the inclined rolling mill, the rolled material rotates around its axial center edge and moves in the axial length direction, so-called spiral movement, which causes the axial length of the rolled material to change. Each part in the axial direction contacts each roll sequentially, but if the number of times the roll contacts the reeling part exceeds a predetermined value, the variation in the diameter of each part in the axial direction of the product will become extremely small. It is effective to increase the length of the beam-ring part as a roll condition to achieve this.If the ring part is made too long, spiral marks will occur due to a decrease in mill rigidity, so reeling There is an upper limit to the length of the part, and its setting is determined by the factors that influence the number of contacts, such as the inclination angle of the roll, the outside diameter of the rolled material set by the roll,
We found that it is necessary to set this by taking into consideration the number of rolls, etc. By the way, an example of roll dimension specifications for a 30-roll type inclined rolling mill using conventional cone-type rolls (diameter 20m)
The roll used to obtain m bars has a barrel length of 120
Crane, reeling length: 30m, gorge diameter: 1
2tas, and the number of times each part of the rolled material contacts the ring part in the longitudinal direction is about 4.5 times when the roll inclination angle is 12 degrees.

Table 1 shows the results of tests conducted by the present inventors to determine the relationship between roll conditions and diameter dimensional accuracy of finished products. The sample material is 50 cranes in diameter made of 345C.

Using a 60mm, 705m bar, it was heated to 1200℃.
The diameter of each part in the axial direction was detected by heating at a stretching ratio of 4 and detecting the diameter of each part in the axial direction.0 In the column showing the results in Table 1, the Q mark indicates that the diameter deviation of the finished product is within ±0.05ta, and the Δ mark indicates ±0. .05f
i is within ±0.10 m, and the X mark indicates ±0.10 mm or more.

Note that the number of times of contact at the reeling portion is a value obtained by measuring the axial velocity component and rotational velocity component of the rolled material during test rolling.

(Leaving space below) Table 1 As is clear from Table 1, among various conditions, the dimensional accuracy of the product is closely related to the number of times each part of the rolled material in the axial direction contacts the reeling part, and the number of contacts is 7. It can be seen from the above that the diameter dimensional accuracy of the finished product is extremely good.

The present invention has been made based on this knowledge, and its purpose is to set the length of the reeling part of the roll to a predetermined value or more, so that each part in the axial direction of the rolled material is set to a predetermined length with respect to the reeling part. It is an object of the present invention to provide an inclined rolling mill that can significantly improve diameter dimensional accuracy by making contact more than once.

The inclined rolling mill according to the present invention has three or four cone-shaped rolls facing around the pass line of the rolled material, the axis of which is inclined at a required angle of inclination and crossing angle with respect to the pass line. In an inclined rolling mill that performs elongation rolling by performing spiral movement, in which the rolled material is rotated along its axial center line and moved in the axial direction, the length of the roll glue-ring part is An inclined rolling mill characterized in that l is set to satisfy the following formula.

m where d: set outer diameter (outer diameter at the exit side of the rolling mill) β: angle of inclination m: number of cone-shaped rolls [Example] The present invention will be specifically described below based on drawings showing examples thereof. Fig. 1 is a front view showing the arrangement of rolls when the inclined rolling mill according to the present invention (hereinafter referred to as the product of the present invention) is used in a 30-mill type, and Fig. 2 is a cross section taken along the line ■-■ in Fig. 1. 3 are side views showing the positional relationship between the pass line and the rolls. In the figures, 1, 2 and 3 indicate cone-shaped rolls, and 4 indicates a solid rolled material. The three rolls 1, 2.3 have approximately the same shape, and have gorge portions 1a, 2a near the downstream end (referred to as the exit end) in the moving direction of the rolled material 4.

3a, with the gorge parts 1a+2a and 3a as boundaries, the diameter is gradually reduced toward the upstream end (referred to as the inlet end) in the moving direction of the rolled material 4, and the diameter is gradually expanded toward the outlet end. The entrance surfaces tb each have a truncated conical shape.

2b, 3b and exit surface (hereinafter referred to as reeling part) 1c
.

Equipped with 2c and 3c.

Both rolls L and 2.3 have their entrance surfaces 1b and 2b.

3b is positioned on the upstream side in the moving direction of the rolled material 4,
The intersection point between the axis Y-Y and the plane including the gorge portions 1a+2a and 3a, that is, the setting center 0, is set as the pass line X- of the rolled material 4.
They are arranged at approximately equal intervals around the bus line XX on the same plane perpendicular to the line X. Also each roll 1,
2.3 is the rolled material 4 whose axial center line Y-Y is around the setting center 0.
In relation to the pass line XX of the first . As shown in FIG. 3, the inlet end is inclined toward the same side in the circumferential direction of the rolled material 4 by an inclination angle β.

Incidentally, the inclination angle β and crossing angle γ of the rolls are 0°
It is set to satisfy the following conditions: γ<15°3°<β<20°5°<γ+β<30°.

Each of the rolls 1, 2, and 3 is connected to a drive source (not shown), and is driven to rotate in the same direction as shown by arrows in FIG. At this point, the shaft is rotated along its axis and moved in the longitudinal direction of the shaft, so-called spiral movement, while being subjected to high pressure that narrows the diameter.

The axial length walking dimension E of the reeling portions 1c, 2c, 3c of the rolls 1, 2.3 in the product of the present invention is determined by the length of the axial length walking dimension E of the reeling portions 1c, 2c, 3c of the rolls 1, 2.3 in the process in which each longitudinal portion of the rolled material 4 passes between the rolls 1, 2.3. The reeling parts 1c, 2c, and 3c of 2.3 are set as shown in the following formula (1) so as to come into contact with the reeling parts 1c, 2c, and 3c more than the total bear times.

17.6d tanβ β≧□ ...(1) where n is: d: Set outer diameter m: Number of installed rolls (3 or 4) The number of times of contact is 7 or more as shown in Table 1 mentioned above. This is based on the test results, and the upper limit is not particularly limited.However, since the diameter dimensional accuracy cannot be improved beyond a certain level, it may be set in consideration of production efficiency, etc.

FIG. 4 is an explanatory diagram showing another configuration of the roll in the product of the present invention, in which the reeling portion lie is configured to be concave in an arcuate cross-section from the gorge portion 11a to the outlet end. The radius of curvature of this reeling portion 11c is the bus line
- When the roll is placed on the X-ray surface, the reeling part 11
The distance between each part in the axial direction of c and the pass line XX is geometrically calculated to be approximately equal to the distance between the gorge portion 11a and the pass line XX.

By the way - as an example roll diameter: 150 m, roll crossing angle: 5°, roll inclination angle: 6°, 9°, 12°.

15°, rolling mill exit side setting diameter: 25 fl, the difference between the geometrically calculated optimum diameter of the ring section roll and the straight truncated conical roll diameter of the ring section roll (Tsuru:
(referred to as the outer diameter difference) and the roll axial direction ratio M (from the gorge part)
fi) is shown in FIG.

The induction process of the above formula (11) will be explained below.

Each part of the rolled material in the axial direction and the roll 1. 2. The number of times of contact with the reeling parts 1c, 2c, and 3c of No. 3 is calculated based on the axial velocity component VX of the rolled material 40 and the circumferential velocity component Vt of the rolled material 4. By the way, these axial longitudinal velocity components vx
, the rotational direction speed component vt is the axial advance rate η of the rolled material 4 in the gorge section, the rotational direction advance rate ζ, the axial speed component Vx of the roll in the gorge section, and the rotational direction speed component Vt of the roll in the rotational direction. The following f21.
(There is a relationship like equation 31.

1 + 77 = vx / Vx - (211+
ζ=vt/Vt (3) The speed component Vx of the roll in the axial direction of the rolled material in the gorge portion and the speed component Vt of the roll in the rotational direction of the rolled material can be expressed as in the following equations (4) and +51, respectively.

πND Vx = -sin β (Tsuru/sec) ・+41 πND Vt −-cos β (Tsuru/sec”) ・(51 However,
N: Roll rotation speed (r, p, a+,) D: Gorge diameter (Tsuru) Therefore, from equations (2) to (5), the axial speed component VX of the rolled material in the gorge and the rolling of the rolled material The material rotational direction velocity component vt can be expressed as shown below (Equations 61 and +71).

πND vx=Vx(1+η) = −sinβ(1+η)...
・(6) πND vt−Vt(1+ζ) = −cosβ(l+ζ)・・
・(n Now, the diameter of the exit side of the rolled material 4 is d: The number of rotations on the exit side is n(r, p
, a+, ), the rotational direction component vt of the rolled material at the gorge portion can be expressed as shown in equation (8) below.

πnd "vt-□...(8) Therefore, the following equation (9) is derived from equations (71 and (81).

D n = -cos β (1 + ζ) (9) On the other hand, if the number of times each part in the longitudinal direction of the rolled material contacts the reeling part is times, then k can be expressed as in the following α equation.

However, m: Number of rolls installed (usually 3 or 4) E: Length of the reeling part (fi) above +61. ((+1. From formula a1, k is as follows (11
) can be rewritten as the formula.

1+ζ Therefore, from equation (11), the axial length l of the glue ring part can be expressed as shown in equation (12) below, where k is the number of times the longitudinal direction of the rolled material contacts the reeling part of the roll.

By the way, in equation (12), there are 7 times as mentioned above, and f is expressed as a function as shown in equation (13) below, and it has been experimentally confirmed that 0.8≦f≦1.8. has been done.

f−f (β, a, α, EN, D/d2, ・
...) ... (13) However, α: Reduction surface angle of the roll on the input side of the rolled material El: Stretching ratio ((input diameter of the rolled material/output diameter of the rolled material) 2) D/d2: Gorge Substituting the lower limit value of 0.8 for f into the equation (12), l
The lower limit range of is given by equation (11).

In addition, in order to actually make the number of contacts at the beam-ring part seven times, the value of f that matches the pass schedule is set as (12).
By substituting into the formula, the appropriate value of l can be found.

Next, test results of the product of the present invention will be explained.

In the test, a 545C bar (50 mm in diameter) was stretched to a diameter of 25 m at a stretching ratio of 4.0 using three types of rolls with different sizes and shapes of reeling parts, and the diameter of each part in the axial direction was measured. did.

Type of roll (al) The length of the reeling part is 50 m, the reeling surface is a truncated cone, and the face angle is 095° (the number of contacts between each part in the longitudinal direction of the rolled material and the reeling part is 11.5 times) ) (bl The length of the reeling part is 50 fl, the reeling surface is in the shape of a truncated cone, and the circumference is a concave surface as shown in Fig. 4. The number of times the reeling part contacts each longitudinal part of the rolled material is 11. .5) (C) Length of reeling part 10
fi, the reeling surface was a truncated cone, and the circumference was a concave surface as shown in FIG. 4. The roll and other dimensions were as follows.

Roll gorge diameter: 150fi, intersection angle: 3°,
Inclination angle β: 15°, roll rotation speed: 100r, p,
Heating temperature: 71,100° C. The results are shown in FIGS. 6(a), (b), and (c). In each of FIGS. 6(a), (b), and (c), the horizontal axis represents the length (u) in the axial direction, and the vertical axis represents the diameter deviation. Figure 6 (a).

(b) shows the results for the product of the present invention, and FIG. 6 (c) shows the results for the comparative example. As is clear from this, when the product of the present invention is used, the diameter variation is within ±0.05m, and when the comparative example is used, the diameter variation is ±0.10.
It can be seen that the dimensional accuracy of the diameter is significantly improved compared to mm.

The cross-sectional shape of the rolled material is preferably circular, but it may also be a solid or hollow bar with a hexagonal or more polygonal shape.

This is because the material to be rolled is rolled while being rotated, and if the material has few corners, the impact on the rolling mill will be large, which is undesirable, and a rectangular cross section is unsuitable.

[Young fruit]

As described above, in the present invention, the length of the reeling part of the roll is set to a predetermined value, and each part in the axial direction of the rolled material can be brought into contact with the reeling part more than a predetermined number of times. The present invention has excellent effects, such as being able to significantly improve diameter dimensional accuracy.

[Brief explanation of drawings]

Fig. 1 is a front view showing how the rolls are arranged in the product of the present invention, Fig. 2 is a sectional view taken along line nn in Fig. 1, Fig. 3 is a side view showing the inclination angle of the rolls, and Fig. 4 is An explanatory diagram showing another configuration of the roll used in the product of the present invention, FIG. Figure 6 (a), (b). (c) is a graph showing the comparative test results of the products of the present invention. 1... Roll 1c... Reeling part 2... Roll 2c... Reeling part 3... Roll 3C.
... Reeling section 4 ... Rolled material patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono 1 Illustration 2 Illustrations 3 Diagram book 45fJ

Claims (1)

[Claims] 1. Three or four cone-shaped rolls are placed facing around the pass line of the rolled material, and their axes are inclined at a required angle of inclination and crossing angle with respect to the pass line. In an inclined rolling mill that performs elongation rolling by performing spiral movement, in which the rolled material is rotated around its axis and moved in the axial direction, the length l of the reeling part of the roll is An inclined rolling mill characterized by being set to satisfy the following formula. l≧(17.6d tanβ)/m where d: Set outer diameter (outer diameter at rolling mill exit side) β: Inclination angle m: Number of cone-shaped rolls