JPS644846B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rolling method in a Tristar roll rolling mill, specifically, a non-driven small-diameter central work roll and rolls arranged radially at approximately equal intervals (shifted by approximately 120°) around its outer circumference. Consisting of three peripheral work rolls, rolling is performed by wrapping the material to be rolled around approximately 2/3 of the circumference of the central work roll so that three rolling points are obtained between these four work rolls. The present invention relates to a method for performing stable rolling using a rolling mill (hereinafter referred to as a Tristar roll rolling mill).

The applicant previously proposed the TriStar roll rolling mill as a rolling mill to replace the conventional 4-high rolling mill, 6-high rolling mill, and continuous cold rolling mill in which rolling mills are arranged in tandem. -134058, Japanese Unexamined Patent Publication No. 1983-94706). FIG. 1 shows the basic principle of the TriStar roll rolling mill. As shown in the figure, three
The outer work rolls 2, 3, and 4 are arranged so that the angle formed by the line connecting the center of the center work roll 1 and the center of each outer work roll 2, 3, and 4 is approximately 120 degrees. . Rolled material (strip) 5
is inserted between the first outer circumference work roll 2 (hereinafter referred to as the entry side outer circumference work roll) and the center work roll 1, and then the second outer circumference work roll 3 is wound around the center work roll 1. (hereinafter referred to as the intermediate peripheral work roll) and the center work roll 1, and further passes between the third peripheral work roll 4 (hereinafter referred to as the output side peripheral work roll) and the center work roll 1. Boarded. The strip 5 is therefore wrapped around approximately two-thirds of the circumference of the central work roll 1 and is wound around three rolling points, namely the rolling points between the central work roll 1 and each of the peripheral work rolls 2, 3, 4. It will be rolled down simultaneously by A, B, and C.

In this tristar roll rolling mill, the central work roll 1 is non-driven and configured to have a diameter as small as possible, and the outer peripheral work rolls 2, 3, and 4 are driven, for example, at separate peripheral speeds, and the rolling mechanism is Work rolls 2, 3, and 4 are the main work roll 1
Since the rollers are arranged at approximately geometrically equiangular positions with respect to the rollers, it is sufficient to install them on any one peripheral work roll.

The advantages obtained by the above-mentioned Tristar roll rolling mill and its rolling method are as follows.

The center work roll can be geometrically reduced in diameter to about 1/6.46 of the outer work roll, and the equivalent roll diameter in terms of rolling mechanics, including the center work roll and the outer work roll, can be reduced to about 1/3.73. It is possible to reduce the length of the contact arc during rolling to approximately 1/1.93 compared to normal symmetrical rolling using two work rolls with the same diameter as the outer work roll, without considering roll flatness. Therefore, the rolling load can be significantly reduced.

In addition, since rolling is performed three times at the same time in one pass, it is possible to roll with a high reduction rate per stand, and conversely, rolling is possible with a high reduction rate per stand.
If an attempt is made to obtain the same reduction rate as rolling by a plate rolling mill, a significant reduction in rolling load will be achieved.

The circumferential speeds of the rolls on both sides of the strip at rolling points A and C are different, and the frictional forces received from the rolls are in opposite directions on both sides, so that the so-called friction hill disappears and the rolling force decreases.

By reducing the diameter of the work rolls and reducing the rolling load, the rolling mill equipment can be made more compact and the number of stands can be reduced.

The rolling reaction force can be reduced by the rational arrangement of the central work roll and three peripheral work rolls, making it easy and efficient to roll hard materials with high deformation resistance or thin strips that are difficult to roll. This makes it possible to do so.

However, when applying such a Tristar roll rolling mill to actual rolling work, the present inventors conducted further experimental research on a rolling method that would ensure stable rolling, and as a result, the Tristar roll rolling mill In order to elucidate the rolling process and perform stable rolling without strip sagging or surface flaws, it is necessary to investigate the different speed ratios of the inlet and outlet peripheral work rolls, the inlet plate speed of the material to be rolled, and the intermediate peripheral work rolls. The present invention was completed based on the knowledge that control of circumferential speed, etc., is an important factor.

The object of the present invention is to prevent rolling problems such as sagging and surface defects in the rolled material during the rolling process without impairing the advantages of the Tristar rolling mill described above, and also to prevent problems in terms of quality. It is an object of the present invention to provide a rolling method that can perform stable rolling operations without any of these inconveniences.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below, but prior to that, the principle of Tristar roll rolling confirmed by the present inventors will be described.

The tristar roll rolling shown in FIG. 1 can be replaced with the same tandem mill as shown in FIG. 2 if the rolling points A, B, and C are considered independently. 3 in tristar roll rolling
If the circumferential speeds of the driven peripheral work rolls 2, 3, and 4 are respectively v ₁ , v ₂ , and v ₃ , then the relationship is v ₁ < v ₂ < v ₃ , and the non-driven central work roll 1 is used for the peripheral work. It rotates while being restrained by the rolls, but its circumferential speed is the second
It almost coincides with the (intermediate) outer peripheral work roll 3. Therefore, in the model shown in Fig. 2, the first rolling point A
It can be seen that the rolling at the third rolling point C is different circumferential speed rolling, and the rolling at the second rolling point B is normal rolling although it is different diameter rolling.

Different circumferential speed rolling, also known as PV rolling, involves approximately 1/2 of the rolling speed of two work rolls of the same diameter.
This is a rolling method in which the sheet is wound around the circumference in opposite directions and rolled, and the thickness ratio (=reduction ratio) on the entry side and the exit side is determined by the different speed ratio of the two rolls. In this PV rolling, the inlet and outlet plate speeds match the inlet and outlet work roll circumferential speeds, respectively.
In addition, since there is no neutral point, friction hills disappear and the rolling force is reduced, and since the plate thickness ratio is determined only by the different speed ratio, it is not affected by changes in rolling force due to roll eccentricity, etc. There are advantages.

Even in tri-star roll rolling, if we take out only the first rolling point A and the third rolling point C (ignoring the second rolling point), we can think of it as different circumferential speed rolling. When the rolling point A and the third rolling point C are considered together, the deformation of different circumferential speed rolling with a floating roll (center work roll 1) interposed in between, that is, the first outer circumferential work roll 2 and the third outer circumferential work roll This can be said to be rolling in which the rolling reduction ratio is determined by the different speed ratio of the work rolls 4. However, in reality, in Tristar roll rolling, the rolling reduction rate is affected by fluctuations in the rolling force, similar to normal rolling.
Since there is a rolling point B, the above theory of PV rolling cannot be applied as is, but on the other hand, if the distribution of the rolling reduction at the second rolling point B is made as small as possible, PV rolling is not affected by the rolling force. It turns out that it is possible to get close to . Note that reducing the rolling reduction ratio at the second rolling point B is also necessary in order to perform stable tri-star roll rolling, as will be described later.

Further, in order to perform stable rolling in tri-star roll rolling, the settings of the peripheral speeds of the peripheral work rolls 2, 3, and 4 to be driven and their relationship to each other are important control elements. If the circumferential speeds of these outer peripheral work rolls cannot be grasped in a constant relationship, tristar roll rolling will not be stable, resulting in problems such as inability to roll, occurrence of sagging of the strip, and occurrence of strip flaws. Therefore, as mentioned above, in the first peripheral work roll and the third peripheral work roll in Tristar roll rolling,
If rolling similar to rolling is performed, these first
The roll circumferential speed of the third outer peripheral work roll can be set by the different speed ratio determined by the rolling reduction ratio. However, in actual tristar roll rolling, due to the existence of the second rolling point, the strip speed on the entry side does not always match the circumferential speed of the first peripheral work roll on the entry side, and the strip speed at the second rolling point at the second rolling point
Setting the circumferential speed of the outer circumferential work roll itself is also a problem.

The present invention proposes a tri-star roll rolling method that involves setting the roll circumferential speed of each of the peripheral work rolls. The actual practice of Tristar roll rolling and the specific content of the present invention will be described below based on the results of experiments conducted by the present inventors.

Figure 3 shows the material to be rolled (JIS SPHC,
2 is a chart showing the relationship between rolling force and cold rolling rate when rolling a plate (thickness: 2.0 mm x width: 160 mm) while varying the different speed rate. In addition, the different speed ratio (x) is the circumferential speed of the first outer circumferential work roll v ₁ and the circumferential speed of the third outer circumferential work roll v ₃
Then, it is expressed as follows.

x = v ₃ - _{v 1} / v ₃ As shown in Figure 3, the most remarkable point in Tristar roll rolling is that within a certain rolling reduction range, each curve has a nearly flat part in the middle. It is. If the different speed ratio (x) is increased, the cold rolling rate increases, but although this flat portion shifts laterally to some extent, its existence is not lost. Moreover,
When looked at in detail, the flat portion slightly slopes upward to the right as the rolling force increases, but it is recognized that it basically follows the line of the rolling ratio corresponding to the different speed ratios.
Furthermore, rolling is of course performed with a rolling force that deviates from this flat area, and the rolling reduction rate changes depending on the rolling force, but the strip becomes sagging and the occurrence of flaws is significant, making it impossible to maintain stable rolling. It was possible.

From the above, in Tristar roll rolling, as mentioned above, there are parts where the influence of different circumferential speed rolling is strong, and parts that are almost the same as normal rolling, especially as shown in Figure 3. If rolling is performed in a nearly flat area, the element of different circumferential speed rolling is strong and stable rolling can be performed. In other words, the shaded area shown in Fig. 3 can be said to be the stable rolling area, and if rolling is performed within this area, the plate thickness will be controlled by the speed ratio of the first and third peripheral work rolls without being affected by fluctuations in rolling force. It is fixed and there is no problem in terms of quality. In addition, although FIG. 3 shows the cold rolling ratio a at the second rolling point between the second peripheral work roll and the center work roll, the rolling ratio at the second rolling point in the stable rolling region is approximately 15% or less. .

Therefore, in the present invention, first, the different speed ratios of the input side peripheral work roll and the output side peripheral work roll are set so as to match the required rolling reduction ratio. In this case, the relationship between the peripheral work roll and the strip plate speed is that the exit peripheral work roll matches the strip speed, but the incoming peripheral work roll peripheral speed and the strip plate speed are due to the existence of the second rolling point. Therefore, they do not necessarily match. Figure 4 shows the different speed ratio (x)
The relationship between the rolling reduction and the cold rolling rate when set to 0.495 is shown in an enlarged manner, and the inlet plate speed (x mark) and the outlet plate speed (△ mark) are also shown. In addition, in Fig. 4, the rolled materials are the same as in Fig. 3, v ₁ : 3.18, v ₂ : 4.13,
_v3 : 6.30 (m/min).

As can be seen from Figure 4, the inlet plate speed corresponding to the stable rolling area (flat rolling area) is within ±10% of the peripheral speed of the first outer work roll (v ₁ = 3.18 m/min). I'm wandering. If the entrance plate speed deviates from the range of ±10% of the circumferential speed of the first outer circumferential work roll, it will be outside the stable rolling region and stable rolling will not be performed.

Next, when maintaining the inlet plate speed within the range of ±10% of the roll peripheral speed, the problem is how to set the peripheral speed of the second outer peripheral work roll. In the present invention, the speed of the second outer peripheral work roll is determined by detecting the speed of the center work roll and using this detected value as a reference.
That is, the circumferential speed of the second outer circumferential work roll is adjusted to the circumferential speed of the center work roll to prevent the center point from shifting.

A specific example of an apparatus for carrying out the method of the present invention is shown in FIG. 1 is the center work roll, 2,
3 and 4 are first, second, and third peripheral work rolls arranged radially around the central work roll 1; 5 is the central work roll 1 and each of the peripheral work rolls 2, 3,
This is a strip that passes through the 4 spaces. Further, 6 is a rewinding reel (rewinding tension applying device) for feeding the strip 5 through the entrance side deflector roll 7;
Reference numeral 8 denotes a take-up reel (winding tension applying device) for winding the rolled strip via the outlet deflector roll 9, 10 a drive device (speed controllable) for the first outer work roll 2, and 11 a first outer circumference. A circumferential speed measuring device for the work roll 2, 12 and 13 a drive device (speed controllable) and a circumferential speed measuring device for the second outer circumferential work roll 3, and 14 and 15 a drive device (speed controllable) for the third outer circumferential work roll 4 ) and peripheral speed measuring device, 16
is a peripheral speed measuring device for the central work roll 1.

Furthermore, 17 is a measuring device installed on the deflector roll 7 to measure the inlet strip speed;
21 is a measuring device provided on the deflector roll 8 for measuring the plate speed of the exit strip; 21 is a rolling force measuring device provided on the second outer peripheral work roll 3; and 22 is a rolling device. For both the above-mentioned driving device and measuring mechanism, publicly known methods may be adopted. Further, 23, 24, and 25 are circumferential speed control devices for the first outer circumferential roll, second outer circumferential roll, and third outer circumferential roll, respectively, 26 is a speed setting calculation device for the first and third outer circumferential rolls, and 27 is a target rolling reduction rate setting. 28 is a rolling reduction rate correction device based on the plate thickness on the inlet side or the outlet side, 29 is an inlet plate speed control device, 30 is an inlet plate speed range setting device based on tension conditions, 31 is a rolling reduction control device, 32
is a reduction force setting calculation device.

In the mechanism shown in FIG. 5, the strip 5 is passed along a predetermined path, and rolled by applying a desired tension with unwinding and take-up reels 6 and 8. The different speed rates of the roll 2 and the third outer peripheral work roll 4 may be set and driven so that the respective peripheral speeds match the target rolling reduction ratio. The plate thickness is controlled based on changes in the input plate thickness or the exit plate thickness during rolling.
This is done by controlling the peripheral speed of one of the outer peripheral work rolls. For example, a speed setting calculation device 26 that provides a reference signal to the roll circumferential speed control devices 23 and 25 of the first and third outer peripheral rolls is connected to a target reduction rate setting device 27 determined from the thickness of the material to be rolled and the thickness of the finished product during rolling. The circumferential speed ratio of the first and third outer circumferential rolls is determined by a signal from a device 28 that corrects the target rolling reduction rate based on changes in plate thickness on the inlet side or the outlet side.

On the other hand, the inlet plate speed is measured by the inlet plate speed measuring device 17, and this is maintained within a range of ±10% of the circumferential speed of the first outer peripheral work roll 2. The peripheral speed of the center work roll 1 in this state can be obtained by the measuring device 16, and this detected value is input to the control section of the second outer work roll 3, and the second outer work roll 3 is controlled by the center work roll 1. It is driven at a speed that matches the circumferential speed of No. 1. As a result, each of the outer circumferential work rolls 2, 3, and 4 is driven at a circumferential speed that enables the most stable tri-star roll rolling (that is, within the stable rolling region).

Note that the rolling control device 31 that controls the rolling device 22 is checked by the rolling force measuring device 21 below the second outer peripheral roll based on a signal from the device 32 that calculates the required rolling force from the rolling conditions. The entry side plate speed control device 29 is a device 30 that compares the values of the entry side plate speed measuring device 17 and the first outer circumferential roll circumferential speed measuring device 11 and sets an allowable range of the entry side plate speed of ±10% or less depending on the tension condition. The operation is controlled and a signal for changing the rolling force is given to the rolling control rolling point 31.

The circumferential speed, plate speed, rolling force, etc. of each roll may be appropriately controlled in consideration of the values detected by each measuring device, the rolling operation, the surface properties and shape of the strip, etc.

As explained above, according to the rolling method of the present invention, tri-star roll rolling can be stably performed and its practical application is possible, so its industrial significance is extremely large.

[Brief explanation of drawings]

Figure 1 is a roll arrangement diagram showing the basic configuration of the Tristar roll rolling mill, Figure 2 is an explanatory diagram showing the analytical model of Tristar roll rolling, and Figure 3 is the experimental results of Tristar roll rolling, showing the rolling force and Figure 4 is an enlarged chart showing the relationship between rolling force and cold rolling rate at one different speed ratio (0.5) and the entrance plate speed at that time. The figure is an explanatory diagram showing a specific example of an apparatus for carrying out the method of the present invention. 1... Center work roll, 2, 3, 4... Outer work roll, 5... Strip, 6... Rewinding reel, 7, 9... Deflector roll, 8... Winding reel, 10, 12, 14 ... Drive device, 11,
13, 15... Peripheral speed measuring device, 16... Center work roll circumferential speed measuring device, 17, 18... Plate speed measuring device, 2
1...Reduction force measuring device.

Claims (1)

[Scope of Claims] 1. Three driven work rolls are arranged radially at approximately equal intervals around the outer periphery of a non-driven small-diameter central work roll, and three rolling points are formed between the center work roll and three outer peripheral work rolls. In the rolling method in the Tristar roll rolling mill, in which the material to be rolled is wound around approximately 2/3 of the circumference of the central work roll and rolled, the outer peripheral work roll on the entry side and the outer peripheral work roll on the exit side are rolled. Set the different speed rate to match the required rolling rate, and detect the speed of the center work roll under the condition that the speed of the rolled material on the entry side is within ±10% of the circumferential speed of the peripheral work roll on the entry side. A method for stable rolling in a Tristar roll rolling mill, characterized in that the circumferential speed of the intermediate work roll is adjusted to the circumferential speed of the center work roll based on this detected value.