JPS5886951A - Controlling method of centering roll of ring rolling mill - Google Patents

Abstract

PURPOSE:To prevent generation of flapping and a multi-angle component, by specifying an angle against the mill center line by a line connecting the center of a centering roll and the center of a ring blank, extending from the rolling initial stage and the rolling middle stage to the end stage, respectively. CONSTITUTION:A part of a ring blank A is pinch-held in the radial direction by a main roll B and a mandrel roll C, the mandrel C is moved, the ring blank A is thinned by gradually narrowing a space against the main roll B, and its outside diameter is made large. In this case, at the rolling first stage, a centering roll E is supported at position where an angle made against the mill center line by a line connecting its center and the center of the ring blank A becomes 90 degrees. Also, in case of the rolling middle stage through its end stage, it is moved so as to make an angle between 72 degrees and 90 degrees, or 90 degrees and 120 degrees (provided that 72 degrees, 90 degrees and 120 degrees are not included).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling centering rolls in a ring rolling mill.

As shown in Figure 1, a ring rolling mill is used to press a thick ring blank A between a main roll B and a mandrel roll C, drive the main roll B to rotate, and move the mandrel roll C to the next fan. A predetermined completed ring A is obtained by bringing the ring blank A closer to the main roll B and increasing its diameter by thinning the ring blank A. However, simply moving the mandrel roll C closer to the main roll B may cause cracks to occur at the start of rolling, the smooth progress of rolling to be hindered in the middle and late stages of rolling, and polygonal components to occur. A pair of centering rolls E are provided to prevent this.

In other words, the centering roll E, which is moved while being in contact with the outer peripheral surface of the ring blank A whose diameter grows, suppresses the flapping caused by the thickness and deformation of the ring blank A in the early stage of rolling, and rolls the ring blank A as quickly and smoothly as possible. It acts to make it into a rolled state. If the support provided by the centering roll E is not strong enough, the ring will continue to flutter, and depending on the conditions, it may become impossible to roll the ring.

In addition, the centering roll E allows the ring to be located approximately at the center of the mill even if there is some disturbance during the diameter growth period of the ring A, helping to perform smooth rolling. However, the contact position to ring A must not be such that it promotes polygonal components of the ring. In addition, there are some machines in which the center position of ring A is controlled by the number of revolutions of a tapered roll for seven-cow shear rolling, that is, a centering roll that has almost no force for correcting the ring center position, but the above situation does not occur. The same applies to such types.

At the final stage of ring rolling, the centering roll E is firmly fixed at an ideal position commensurate with the ring diameter at that time, and corrects polygonal components generated during the diameter growth stage.

The centering roll is required to have such a complex function, but in the prior art, no centering method was known that could fully meet this requirement. That is, for example, in the centering method disclosed in Japanese Patent Publication No. 52-36957, a line connecting the initial center point of the centering roll and the center point of the ring material before rolling;
It is also claimed that the line connecting the center point at the end of the movement of the centering roll and the theoretical center point of the ring material after rolling is parallel to each other. However, no mention is made of the size of the angle that each of the above lines makes with the mill center a (the line connecting the center of the main roll and the center of the mandrel roll). Furthermore, there is no explanation as to why it is desirable for rolling to have both wires parallel to each other. However, as will be explained later, these are very important requirements for performing good rolling, and if their selection is inappropriate, the above-mentioned fluttering phenomenon will easily occur or polygonal components will be promoted. That will happen. For example, selecting α-90° and keeping this angle constant during rolling is preferable at the beginning of rolling, but becomes unfavorable for the roundness of the ring at the end of rolling.

Based on such a technical background, the present invention firmly supports the ring blank in the early stage of rolling to suppress the fluttering that occurs therein, rolls the ring smoothly at least during the diameter growth stage, and further The purpose of this invention is to provide a centering roll control method that can correct the polygonal components of the ring at the end of rolling.

Below, we will first consider the requirements of the centering roll at the initial stage and from the middle to the final stage of rolling.

1) Regarding the contact position of the centering roll with the ring blank at the initial stage of rolling: In Fig. 2, the force F applied to the ring blank A by the centering roll E
Therefore, the torque T applied to the rotation of the contact point G between the main roll B and the ring blank A is determined by the line connecting the outer diameter of the ring blank A and the center point of the ring blank A and the center point of the centering roll E. If the angle that the minute makes with the mill center line is α, then T ” F sin α・几.

In order to firmly hold the ring blank A, a larger torque T is effective, and in order to satisfy this condition, it is desirable that α=90°.

2) Regarding the contact position of the centering roll with the ring from the middle stage to the final stage of rolling: As shown in Figure 3, the main support point H1 and the secondary support points I and I' are in contact with the ring for successive perfect circles with average diameters. Assume that there exists a contact point. At this time, if the ring with polygonal components is in a state where it can come into contact with the three points (H, I, I',) shown in the figure without any resistance, this ring will not be affected by the support of these three points. Polygonal components will not be corrected. Furthermore, if the ring could continue to rotate while maintaining this state, there is a risk that this polygonal component would not be corrected but would even be exacerbated. The above-mentioned situation may also occur when the ring is supported by the main roll and centering roll of a ring rolling mill.

Hereinafter, in ring processing using a ring rolling mill, the ring support position by the centering roll that satisfies the above-mentioned conditions will be determined for a polygonal component that is a practical problem.

Here, in a ring having one polygonal component, the distance hole from the virtual center of the ring to a point on the outer periphery is approximately expressed as R" Ro + an sin (nθ + ψn).

However, 几0: Average radius when ring A is a perfect circle an: Amplitude of the polygonal component n: Number of angles of the polygonal component ψn: Initial phase θ Elevation angle from the two reference positions to the point of consideration The model shown in Figure 4 In the figure, 0 is the virtual center when the ring A (not shown) in which the polygonal components occur is made into a perfect circle, and 01
is the virtual center of ring AI that has moved only in the horizontal direction due to strain, the fixed point of ring A by main roll B, and I and I' are the support points of ring A by centering roll E. In this case, by rotating the ring A° around the fixed point H, its contour changes to I
, a ring A''(0'') that coincides with point I'
) exists, this is a state in which the above-mentioned polygonal component cannot be corrected.

Here, if the distance between the virtual center 0 and O゛ is δ0, then δ0; 几lJL.

2aH"Slnψn becomes.

The intersection J of the extension of the line segment OI that forms an angle α with the line segment OH and the ring A1 around the virtual center 01, and ol
If the distance from 1 to a perfect circle with radius Ro centered on is δ(α), then /JO'H-α, so δ(α)=几(α)-R.

=anILSIn(nα+ψn) becomes.

Similarly, the line segment OI' that makes an angle (-α) with the line segment OH and the ring A1 of the virtual center o1
If we set the distance between the intersection J1 and 1 in a perfect circle with radius Ro centered on 01 as δ(-α), /J'O
'H--α, so δ(-α)=几(-α)-几〇=an*sin((-nα)×ψn).

Next, the support point I of the ring by the centering roll E
, I' and the above intersections J and J' are respectively δ1(α) and δ+(-α), then δ゛(α)
is δ°(α)-几′(α)-几〇#I't(α)-δcosα--b = δ(α)-δo”cosα = an* 5in(nθ+ψn) a n@5i
n9) no CoSθ, and the other δ1(-α) is δ 1(-α)=a no sin ((-nα)+ψ
n j an @5In(pn@cos α).

Here, if δ (α) + δ1 (-α) = 0, it is possible to bring the ring Arc into the state shown at All (centered on OII) without applying any force that would deform it. can. In other words, if the centering roll E is on the ideal circumference equal to the average outer diameter of the ringer, then δ
'(α) + δ1(-α) = 0, the real center of ring A moves freely, and the force that corrects the polygonal component does not act on the ring, but on the contrary, the geometric There is a possibility of self-encouragement.

When determining the position where the above self-excitation occurs for the 2-5 angle profit, which is a practical problem, Jl (α) + δ1 (-α) =
2an*sjnψn((os(r+α)−cosα), and in order to always have δ°(α)+δ′(−α)=0, the angle α must satisfy cos(nα)−cosα=0. In other words, the angle α is as follows.When considering 0°≦α and 180°, n =
2 When α=0°, 120° When n=3 α=0', 90°, 180° When n=4 α=0°, 72°, 120°, 144° When n=゛5 α =0°, 60°, 90°, 120°, and 180°, there is a risk that self-excitation will occur.

However, Jin's theory is only an approximation for small polygonal strain components, and may not hold true if the polygonal strain components exceed 10% of the diameter. However, in actual ring rolling, the polygonal strain component that occurs is only about a few percent of the diameter, so this theory holds true.

In the present invention, from among the above-mentioned angles, 72[deg.] x 90[deg.] or 90[deg.] x 120[deg.]t- is adopted. For example, α=60
This is because if the angle α is 72° while changing the angle α from 90° to 60°, polygonal components may occur. The same holds true for α=144° and so on. That is, in the method for controlling the centering roll according to the present invention, the centering roll is placed at a position perpendicular to the mill center line at the beginning of rolling, and from 72 degrees to the mill center line from the middle to the end of rolling. 120
It is characterized by being placed at a position forming any angle within the range of 90° (excluding 90°).

As long as this condition is met, the angle that the straight line connecting the centers of the centering roll E and the ring makes with the mill center line at the end of rolling is smaller than 90° as shown in Figure 5(a). (for example, 80 degrees), or as shown in the same figure, it may be larger than 90 degrees (for example, 110 degrees). However, in the latter case, it is inevitable that the travel distance will be longer than in the former case.

In addition, the movement trajectory and speed are arbitrary in the eye that satisfies this requirement, since the centering roll should retreat while contacting the outer circumferential surface of the ring whose diameter grows, and be within the above angle range at the final office. The trajectory can be either a straight line or a curved line.

Further, the moving speed is determined in relation to the diameter growth speed of the ring.

Next, a rolling mill for carrying out the above control method will be explained based on the drawings.

As shown in FIG. 6 and the off-line diagram, a main roll B is mounted on a base 1 so as to be rotationally driven by a drive mechanism (not shown) via a bearing 2, and a mandrel carriage 3 is hydraulically driven. It is mounted so as to be movable in the left and right direction by a cylinder 4. This carriage 3 has a box shape, and a mandrel roll C is rotatably attached to the open end via a bearing 5.

The main roll B is designed not to obstruct movement of the carriage 3.

A seven-axis carriage 11 is also placed on the base 1 so as to be moved in the left-right direction by a hydraulic cylinder 12, and the amount of relative movement of this carriage 11 with respect to the base 1 is measured by an encoder 17. ing.

And the carriage 11 has a pair of 7xial rolls 15.
a + 15 b is provided to regulate the height of ring A. Roll 13 on one side (lower in the off view)
'a is fixed to the carriage 11, while the other roll 13b is fixed to the hydraulic cylinder 14 fixed on the carriage 11.
The roller 15a is moved toward or away from the roll 15a by the action of the roller 15a.

The centering roll E is fixed to the end of a small screw rod 22 of a hydraulic cylinder 21. Jin's hydraulic cylinder 2
1 is fixed to an inclined surface 24 of a pair of mounting members 23 fixed to the carriage 11, and the movement of the rod 22, that is, the centering roll E, is measured by an encoder 26 fixed to the mounting member 25. ing.

At one end of a rod 31 movably mounted on the base 1, a ring blank A is moved by a cylinder 36.
A roller 32 that comes into contact with the outer circumferential surface of the ring blank A is mounted, and the movement of the roller 32, that is, the growth of the diameter of the ring blank A, is measured by an encoder 33. Each hydraulic cylinder 12.21 and encoder 17
, 26.65 are connected to the control device 35.

Next, to explain the operation of this embodiment, a part of the ring blank A is held in the radial direction by the main roll B and the mandrel roll C, and the opposing part is held in the height direction by a pair of axial rolls 13a and 15b. to hold. Next, the carriage 3, that is, the mandrel roll C, is moved by the hydraulic cylinder 4, and the distance between it and the main roll B is narrowed to the next level, so that the ring blank becomes thinner and its outer diameter increases.

At this time, the centering roll E is retracted while keeping in contact with the outer circumferential surface of the ring A whose diameter increases, but its trajectory is due to the movement of the carriage 11 by the hydraulic cylinder 12 and the movement of the piston rod 22 by the hydraulic cylinder 21. Determined by combination. In short, it is sufficient to satisfy the above conditions at the initial stage and at the final stage of rolling. Also, the outer diameter of the ring A whose diameter grows is measured by the encoder 33.
l When the outer diameter of the ring reaches a predetermined value, the rolling is finished.

These controls are performed by a control device 35. It goes without saying that the rolling in the height direction is performed within the radial rolling schedule period in coordination with the radial direction.

Next, the movement of the centering roll will be explained based on a specific example. FIG. 8 shows the positional relationship between the ring A and the centering roll E at the initial, middle, and final stages of rolling. This figure shows that when the axial carriage 11 is retreated while keeping the theoretical tapered tips of the axial rolls 15a and 15b positioned at the virtual center of the ring A, 4), and the diameter-growing ring A is replaced with a concentric circle. Oo, Om and Of are the center of the centering roll E at the beginning, middle and end of rolling, respectively, and Ro.

R and Rf are the radius of ring A, α□.

α is the angle that the center of the centering roll E in the middle and final stages of rolling makes with the line segment PQK:, β is the angle that the center of the centering roll B in the final stage of rolling makes with the line segment 0°Q, then the initial center of the roll It is expressed by the length of the line segment connecting O and Om.

In this formula, for example, R6-+50111. R-f=20
By substituting 0111, ro=75sn, and β=24°, x''=146 Im.

According to the prior art, as shown in Fig. 9, the completed ring A
However, according to this embodiment, such polygonal components do not occur and a completed ring with high roundness can be obtained.

Note that the angle that the line segment connecting the centering roll E and the center of the ring A makes with the mill center line at the end of rolling is 72 degrees α, 90 degrees, or 90 degrees, α
It can be arbitrarily selected within a range of 120 degrees, and the locus of movement of the roll is not limited to a straight line.

In addition, although the centering roll E was designed to move integrally with the axial carriage 3 in the embodiment shown in FIG. The means may be independent of the seven-axis carriage 3.

As described above, according to the centering roll control method and control device according to the present invention, it is possible to reliably suppress the fluttering of the ring blank in the early stage of rolling, and the rolling control can be performed based on the ring reverse signal. The timing can be advanced, and a ring with sufficient precision can be obtained even when the total reduction lid is small.

Further, from the middle to the final stage of rolling, polygonal components in the ring are not promoted, and if polygonal components occur, they can be corrected to obtain a practical perfect round ring.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for explaining the basic concept of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the ring and the centering roll at the initial stage of rolling, and Fig. 3 is an explanatory diagram for explaining the general theory. Fig. 4 is an explanatory diagram showing the deformation of the ring from the middle to the final stage of rolling, and Figs.
! Figure 16 and off view are respectively a plan view and a front sectional view showing the BAt family 4 filter plate 4 of the present invention, and Figure 8 is a diagram showing the movement of the centering roll in the above embodiment. FIG. 9 is a diagram showing the roundness of a completed ring obtained by the prior art. [Explanation of symbols of main parts] Ring blank (ring) −=−==−−−−−−=
A main roll - + - + + - + + - + + + + + + - + - +
＋＋＋＋＋＋＋−＋ B mandrail roll−−−−
----------------
1------E base------------
−−−−−−−−−m−−−−−−−−−−−−−−
-1 Mandrel carriage---------
------
7 External roller ----------------
---15a, 15b hydraulic cylinder --------
-1----------12, 14, 21 5
Figure (α) (6)

Claims (1)

[Claims] A ring roll that obtains a predetermined ring by gradually moving a mandrel roll closer to the main roll, rolling down the ring blank in the radial direction, and bringing a pair of centering rolls into contact with the outer circumferential surface of the link whose diameter is growing. A method for controlling movement of a centering roll in a ring mill, the method comprising:
At the beginning of rolling, the ring blank is supported at a position where the line connecting its center and the center of the ring blank makes an angle of 90° with the mill center line, and from 72° to 90° or 90° from the middle to the end of rolling. and 120° (however, 72°, 900° and 120° are not included).