JPH02125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a speed control device for a rolling mill that rolls multiple strands of steel bars or wire rods.

[Background technology and its problems]

Steel bars and wire rods are continuously rolled by a plurality of rolling mills equipped with slotted rolls.

Generally, when rolling steel bars and wire rods, tandem mills are used which are configured with a variety of hole shapes. Typical types of hole type rolls include diamond hole type, square hole type, hex hole type, oval hole type,
and round hole types are known, and the billet as a raw material is continuously rolled by successively passing through these holes to form the final product, such as a steel bar or wire rod. Rolling with grooved rolls mainly involves three-dimensional deformation.

On the other hand, in the case of plate rolling, two-dimensional deformation is the main factor in the calculation formula (hole type rolling theoretical formula) for calculating various rolling characteristic values.

When comparing the two, the theoretical consideration of three-dimensional deformation is still insufficient compared to the case of two-dimensional deformation, and it is necessary to improve the rolling design calculation and control in the future. There is.

In normal rolling of steel bars and wire rods, only one unrolled material is used, and in this case, a well-known method is employed to control the tension of the unrolled material. For example, current memory method,
The rolling torque memory method, the rolling load/rolling torque memory method, etc. are used, and these methods have achieved a certain degree of effectiveness in improving the range of quality accuracy allowed for current steel bars and wire rods.

However, it cannot be denied that, although the plastic deformation mechanism is more complex, it is still technically inferior to quality assurance technology based on rolling control of plate materials. In this way, in the rolling of steel bars and wire rods, although the precision is lower than that of plate rolling, in order to improve productivity, two or more non-rolled materials are rolled simultaneously with one rolling roll. Rolling may be performed.

In such multi-strand rolling, 2 strands per strand.
A rolling roll with more than one groove is used.
Although such multi-strand rolling is useful for improving productivity, the factors that influence rolling are complex and control uncertainties are added, making it inferior in terms of quality compared to rolling only one strand of material. It is inevitable that quality will deteriorate.

[Purpose of the invention]

An object of the present invention is to provide a speed control device for a continuous rolling mill that can improve the quality of rolled products by rolling other strands, and in particular, the tension between the stands at the time when rolling is started on a stand with a trailing material. It is an object of the present invention to provide a speed control device having a mechanism for detecting a change and correcting the speed of a rolling roll.

[Summary of the invention]

In order to achieve the above object, the present invention includes a roll speed control device that controls the rotational speed of the rolling roll of each stand, a rotational speed detector that detects the rotational speed of the rolling roll, and a tension force between the stands that is adjusted to a desired value. a tension setting device for setting the tension setting device to a value of In a speed control device for a multi-strand continuous rolling mill that rolls materials to be rolled in parallel with the same rolling roll, rolling of the subsequent material to be rolled starts at the i-th stand (i is an integer), thereby causing a difference between the i-th stand and the upstream. The rolling torque change of the i-th stand corresponding to the tension change between the i-th stand and the i-th stand
means for calculating a roll speed correction value ΔNi for the rolling roll of the i-th stand by calculating based on the output of the rotational speed detector provided in the first stand and multiplying this calculated value by the proportional control gain of the i-th stand; , the rotational speed at which the i+1st stand is provided with a rolling torque change of the i+1st stand corresponding to a change in tension between the ith stand and the downstream i+1st stand due to the rolling of the trailing rolled material being started at the ith stand. The i-th stand and the i+1-th stand are calculated based on the output of the detector, multiplied by the proportional control gain of the i+1st stand, and further calculated from the roll speed correction value ΔNi and the detection value of the rotational speed detector. Stand rolling roll rotation speed Ni,
By adding the correction value calculated from Ni+1, the i-th
Means for calculating a roll speed correction value +1 for one stand of rolling rolls is provided in the calculator, and both roll speed correction values ΔNi, +1 are added to the control signal and output.

The present invention will be described in detail below based on examples.

[Embodiments of the invention]

First, the basic rolling characteristics when rolling of the trailing material is started in multi-stand rolling will be described.

FIG. 1 schematically shows an example of two-strand rolling in which two rolled materials 1 and 2 are rolled at the same time. In Fig. 1A, the preceding material 1 among the materials to be rolled is #
This figure shows a state in which rolling is performed continuously across the i stand and the #i+1 stand, and rolling of the trailing material 2 among the rolled materials has not yet started by the #i stand.

In Fig. 1B, time has passed since Fig. 1A, and the trailing material 2 has reached the #i stand, and the leading material 1 and the trailing material 2 are being rolled at the same time by the slotted roll Ri of the #i stand. The state is schematically shown.

Here, Gi and Gi+1 shown in the figure are #i and #i before the trailing material 2 does not reach the #i stand, respectively.
It shows the rolling torque of +1 stand.
Further, Ti is the inter-stand tension between the #i stand and the #i+1 stand. FIG. 1C shows a chart measured by a pen recorder, showing changes in rolling torque and inter-stand tension with respect to time. ti on the horizontal axis indicating time is #i of the trailing material 2
Indicates the time to start rolling on the stand. Trailing material 2
starts rolling at stand #i, the rolling torque at stand #i+1, which is the downstream stand of stand #i, changes from Gi+1 to Gi+1+ΔGi+1, and #
The inter-stand tension Ti between the i stand and the #i+1 stand is Ti+ΔTi.

In other words, at the time when rolling of trailing material 2 starts on #i stand, backward tension is applied to #i+1 stand even though only preceding material 1 is being rolled.
Ti changes by ΔTi, and rolling torque also changes by ΔGi+1.

At this time, the #i stand changed from the 1-strand rolling state to the 2-strand rolling state, so the rolling torque changed from Gi to Gi+ΔGi. This ΔGi also includes the effect of changing the number of rolled materials from one to two.

At this time, the tension between stand #i-1 and stand #i, which are adjacent upstream stands of stand #i, also changes. In this way, in two-strand rolling, the rolling torque and tension of the stands upstream and downstream of the stand change simultaneously when the trailing material 2 reaches the stand (stand #i in Figure 1). be.

The above explanation is not limited only to the case of two-strand rolling, and the preceding material 1 and the succeeding material 2
If it is determined that not only one strand but two or more strands of material to be rolled have already been rolled, the method is similarly applicable to the case of multi-strand rolling of 3 or more strands.

Next, based on the characteristics of the multi-strand rolling explained above, the basic principle for controlling the tension between the stands when rolling of the trailing material 2 is started will be explained.

Figure 2 shows #i of the rolling mill group for steel bar and wire rod mills.
It is a schematic diagram showing the rolling pattern in three stands of -1, #i, and #i+1. Figure 2 A shows the preceding material 1
is in stand #i+1, trailing material 2 is still #i
This shows a state where the stand has not been reached, and the rolling torques of the stands #i-1, #i, and #i+1 at this time are Gi-1, Gi, and Gi+1.

FIG. 2B shows a state in which the trailing material 2 has started rolling on stand #i, and at this time, #i-1,
The rolling torque of each stand #i and #i+1 is G′i
−1, G′i, and G′i+1.

Here, the reason why the torque changes between A and B in Figure 2 is that the trailing material 2 reaches stand #i and the rolling torque
This is because the tension between stands #i-1 and #i and between stands #i and #i+1 changes simultaneously when Gi becomes G'i. # Trailing material 2 to i stand
The rolling torque change ΔGi+1 of the #i+1 stand due to the tension change between the #i stand and the #i+1 stand caused by the reaching of is ΔGi+1=Gi+1−G′i+1 (1). The tension between the #i stand and the #i+1 stand is the rolling roll Ri+1 of the #i+1 stand.
It is controlled by changing the rotational speed Ni+1 by ΔNi+1. That is, ΔNi+1=gi+1・ΔGi+1 (2) holds true. Here, gi+1 indicates the proportional control gain of #i+1 stand.

Next, the rolling torque change of #i stand is the following material 2
This is the sum of the increase in the rolling torque of the #i stand due to the start of rolling and the change in the front and rear tension of the #i stand due to the rolling start of the trailing material 2.
The rolling torque change ΔGi (i-1) of the #i stand corresponding to the tension change between the #i-1 stand and the #i stand that caused the rolling torque change ΔGi+1 of the #i-1 stand is ΔGi (i-1) , wi+ΔGi-1・wi-1=0 (3). Here, wi and wi-1 are the angular velocities of rolling rolls Ri and Ri-1 of stand #i and stand #i-1, respectively. Here, ΔGi−1=Gi−1−G′i−1 (4) holds, so from equations (3) and (4), ΔGi(i−1)=−wi−1/wi(Gi− 1−G′i−1) (5) is derived. The tension between stand #i and stand #i-1 is controlled by changing the rotation speed Ni of stand #i by ΔNi. That is, ΔNi=gi・ΔGi(i−1) (6) holds true. Here, gi is the proportional control gain of #i stand.

In the case of multi-strand rolling, when the trailing material 2 reaches the stand #i, the longitudinal tension of the stand changes simultaneously. Tension control in multi-strand rolling should be performed based on this basic characteristic, and equations (2) and (6) should be considered simultaneously at the minimum.

Next, specific embodiments based on the basic principle explained above will be explained. FIG. 3 is a block diagram showing an embodiment of a speed control device for a multi-strand continuous rolling mill according to the present invention. In the configuration diagram of Figure 3, #i
Only the −1, #i, and #i+1 stand portions are shown. # The rolling torque Gi at i-stand can be calculated using the following formula.

Gi=βV-IR/NiI-γdNi/dt-δ (7) Here, V is the drive motor 3 that drives the rolling roll.
, I is the motor current, R is the armature resistance, and β, γ, and δ are constants, respectively. The first term on the right side of equation (7) indicates motor torque, the second term indicates acceleration/deceleration torque, and the third term indicates loss torque.

Although a speed reducer is not shown in the configuration diagram of FIG. 3, even if a speed reducer is present, the rolling torque and motor torque required for rolling the material to be rolled can be easily determined.

In this case, both can be converted from the reduction gear specifications (reduction ratio). There is also a certain relationship between the roll angular velocity wi and the motor rotation speed Ni described above. In the configuration diagram of FIG. 3, rolling roll R (Ri-
1, Ri, Ri+1) to drive motor 3 (3i-1,
3i, 3i+1) are driven, and the voltage and current of this drive motor 3 are controlled by a speed control device 7 (7i-
1, 7i, 7i+1),
On the other hand, the rotation speed and voltage, which are the output values of the drive motor 3,
The current value is detected by the speed detector 4 and is as described above.
The calculator 5 calculates the rolling torque of each stand using equation (7), and controls the rotational speed of the drive motor 3 via the angular velocity controller 7 so that the inter-stand tension value is set in advance by the tension setting device 6. It is composed of

Next, speed control will be explained in more detail.
The rolling torque Gi−1, Gi, Gi+1, G′i−1, of each stand before and after the trailing material 2 reaches #i stand,
G′i and G′i+1 are each calculated by the computer 5 according to equation (7) and stored.

Also, ΔNi+1 is obtained from equations (1) and (2), and from equation (5),
ΔNi is calculated by the calculator 5 from equation (6). In multi-strand rolling, the front and rear tensions of the stand (#i stand) where the trailing material 2 starts rolling change simultaneously, and therefore, in multi-strand rolling, it is necessary to control the front and rear tensions at the same time. . In order to control this longitudinal tension, the relevant stand (#i stand) and the downstream stand (i
+1 stand) rotation speed control.

Here, the rotational speed control amount of #i stand is ΔNi calculated by equation (6), and the rotational speed control amount of #i+1 stand is ΔNi + calculated by equation (2).
1 plus the rotational speed control amount ΔNi of the #i stand, which is the total control amount +1. This total control amount +1 is expressed as +1=ΔNi+1+ΔNi/NiNi+1 (8).

At this time # i+1 stand adjacent downstream stand #
The amount of change ΔNi+2 in the rotational speed of the rolling roll of stand i+2 is as follows: ΔNi+2=ΔNi+1/Ni+1Ni+2 (9). Here, Ni+2 is the rolling speed of the #i+2 stand. Furthermore, the downstream stands #i+3 and below are similarly controlled.

FIG. 4 is a diagram showing the internal configuration of the computer 5 shown in FIG. 3. Based on the output value from the speed detector 4 according to the calculation formulas (1) to (8), #
Roll speed correction values ΔNi and ΔNi+1 for the speed control devices 7 provided at the i+1 stand and the #i stand are calculated.

The two roll speed correction values ΔNi and +1 calculated in this way are added to a control signal predetermined by the tension setting device 6, and the result is given to the speed control device 7.

By performing such control, fluctuations in the longitudinal tension that occur when the trailing material reaches the stand (#i stand) are compensated for.

〔Effect of the invention〕

As described above in detail based on the embodiments, in the present invention, when rolling of a trailing material starts on the stand and the rolling state changes during continuous rolling of multiple strands of steel bars or wire rods, the stand and its downstream stand Since the rotation speed of the rolling rolls is controlled simultaneously, the tension applied to the rolled material can be controlled with high precision regardless of whether it is the preceding material or the following material, so the dimensions and roundness of the steel bar or wire rod can be controlled with high precision. It has the advantage of being uniform.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 are diagrams for explaining the basic characteristics of multi-strand rolling, Fig. 3 is a configuration diagram of a speed control device showing an embodiment of the present invention, and Fig. 4 is a diagram for explaining the basic characteristics of multi-strand rolling. It is a diagram showing the internal configuration of a computer. DESCRIPTION OF SYMBOLS 1... Leading material, 2... Following material, 4... Speed detector, 5... Calculator, 6... Tension setting device, 7... Roll speed control device.

Claims (1)

[Claims] 1. A roll speed control device that controls the rotational speed of the rolling rolls of each stand, a rotational speed detector that detects the rotational speed of the rolling rolls, and a tension setting device that sets the tension between the stands to a desired value. a computer that sends a control signal to the roll speed control device in response to the outputs of the rotational speed detector and the tension setting device, and a plurality of rolled materials stretched between the stands are controlled by the same rolling roll. In the speed control device of a multi-strand continuous rolling mill that rolls in parallel, the tension between the i-th stand and the upstream i-1 stand due to the rolling of the trailing rolled material starting at the i-th stand (i is an integer) The rolling torque change of the i-th stand corresponding to the change is calculated based on the output of the rotational speed detector provided in the i-th stand and the i-1 stand, and this calculated value is multiplied by the proportional control gain of the i-th stand. means for calculating a roll speed correction value ΔNi for the rolling roll of the i-th stand, and a means for calculating a roll speed correction value ΔNi for the rolling roll of the i-th stand;
Calculating the rolling torque change of the i+1th stand corresponding to the tension change between one stand based on the output of the rotation speed detector provided in the i+1th stand,
The rolling roll rotation speed Ni of the i-th stand and the i+1-th stand is calculated by multiplying this calculated value by the proportional control gain of the i+1-th stand and further calculating from the roll speed correction value ΔNi and the detected value of the rotation speed detector, Ni+1 and a means for calculating a roll speed correction value +1 for the rolling roll of the i+1st stand by adding the correction value calculated from Ni+1, and the both roll speed correction value ΔNi,
A speed control device for a multi-strand continuous rolling mill, characterized in that ΔNi+1 is added to the control signal and output.