JPH029521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a reversing rolling mill with the aim of improving efficiency.

FIG. 1 is a block diagram showing a generally used reversible rolling mill. In the figure, 1 is a reversible rolling mill having rolling rolls 3 for rolling a rolled material 2 to a predetermined thickness; A drive motor that drives the rolling rolls 3 of the rolling mill 1, 5 a drive motor control device that controls this, 6 a rolling control device that controls the rolling position of the rolling rolls 3, 7 a rolling force measuring device, and 8 a rolling material. A table roller 9 is used to move the table roller 2, and a table roller drive control device 9 is used to drive the table roller 8.

In the reversible rolling mill having such a configuration, when rolling is performed, the rolling rolls 3 are first set to the initial rolling position by the rolling reduction control device 6. Next, the drive motor 4 is driven, and the table roller 8 is driven by the table roller drive control device 9, so that the rolled material 2 is rolled to a constant thickness and exits to the opposite side of the reversible rolling mill 1. Next, similar rolling is performed by setting the rolling roll 3 to the second rolling position and rotating the drive motor 4 and table roller 8 in opposite directions. By repeating this process, the rolled material 2 is rolled to a predetermined thickness.

Therefore, in order to perform rolling most efficiently in the past, the number of passes (rolling number) of the reversible rolling mill, the rolling position of the rolling rolls in each pass, and the rolling speed in each pass should be comprehensively considered, and the rolling material should be After reaching the reversible rolling mill, the rolling schedule setting that would achieve a predetermined plate thickness in the shortest time was determined manually or by a calculation setting machine.

However, considering the characteristics of the drive motor of a reversible rolling mill, this configuration repeatedly accelerates and decelerates,
Because the schedule is set to roll in the shortest possible time despite fluctuations in load, there is a problem in that rolling becomes impossible due to a rise in the temperature of the drive motor.
Furthermore, if the cumulative amount of power required for rolling each pass is calculated, rolling for the shortest time does not result in the minimum required power, so there is a problem in that extra power is consumed.

This invention was made in order to solve these problems, and it is possible to set a rolling schedule that satisfies both the allowable rolling power and the allowable rolling root mean square and also minimizes the rolling time by adjusting the no-load idle time (rolling roll idle time). Efficiency can be improved by controlling the rolling process using the above rolling schedule by calculating the time during which the table rollers placed before and after the table rollers are stopped even though the table rollers are rotating. The present invention provides a method for controlling a reversible rolling mill.

An embodiment of the present invention will be described below.

First, a method of setting a rolling schedule in the present invention will be described.

Rolling specifications such as the hardness of the rolled material, the temperature and thickness of the rolled material at the entrance of the rolling mill, and the target thickness at the exit of the rolling mill, as well as the maximum permissible rolling load, maximum permissible rolling torque, and maximum permissible rolling power of the rolling mill. Once the rolling mill specifications such as the maximum allowable rolling speed, standard rolling speed, and bite angle limit are determined, the minimum number of passes can be determined from the rolling power curve and equation (1) below.

Minimum number of passes = total required power / maximum allowable rolling power...(1
) Here, the required total power can be determined from the rolling power curve as shown in FIG. That is, the power value of the curve at the target plate thickness is approximated to the total power.

In this number of passes, the rolling speed and reverse rotation start timing that provide the shortest selectable rolling time are calculated. At this shortest rolling time, the root mean square value of the rolling power is It is expressed as Here, KW _Ri : Required power for rolling the i-th pass KW _Ii : Required power at no-load, that is, from the end of the i-pass rolling to the start of rolling for the (i+1) pass τ _Ri : Required time for rolling the i-th pass τ _Ii : i-th pass no-load idle time P: number of passes W _RMS : root mean square value of rolling power.

This value is determined and checked to see if it is within the tolerance range of the rolling mill. If it is within the tolerance range, the determined value is set as the optimum schedule value. Furthermore, if the value is outside the allowable range, as can be seen from equation (2), if the no-load idle time is increased, the root mean square value of the required rolling power will be lowered, so this time is changed and recalculated. At this time, from iPass (i+
1) Since the time until the start of the pass changes, the temperature of the material to be rolled will be different from the previous calculation due to the action of radiant heat, so the required rolling power will be different, and the rolling power, rolling speed, etc. will be changed again. Calculate and calculate the root mean square power required for rolling.

The rolling power, rolling speed, etc. are determined by known methods.
For example, you can find it like this:

As mentioned above, the minimum number of passes is determined from the rolling power curve, and the load distribution ratio of each pass, that is, the power distribution ratio, is given by the rolling specifications for this number of passes, so the total required power can be calculated using the following formula (3). Required power for i-pass = (distribution ratio of i-pass) × (total required power) ... (3) If the power is allocated according to the distribution ratio, the exit plate thickness of each pass can be determined as shown in Figure 2.

If the exit side plate thickness of each pass is determined, the inlet side plate thickness is the initial plate thickness.

Once this is determined, the rolling force F(i) for each pass is F(i)=f ₁ (H ₅ (i), h(i), V(i))...(4) Here, H(i): There is a relationship: i-pass entrance plate thickness h(i): i-pass exit plate thickness V(i): i-pass speed, so if i-pass speed V(i) is assumed, the rolling force F(i) of each pass is is found. Once this F(i) is found, the power PW(i) is found from the relationship PW(i)=f ₂ (F(i), V(i))...(5). The i-pass speed V(i) is determined by the rolling mill as V _MIN ≦V(i)≦V _MAX , so V(i) _M
Starting from _AX , it is sufficient to find V(i) when PW(i) becomes less than the maximum allowable power.

Once the outlet plate thickness h(i) and rolling force F(i) are determined, the setting position S(i) of the rolling mill can be determined from the following equation (6).

S(i)=f ₃ (F(i), h(i)) ...(6) By calculating as above, the rolling schedule can be obtained. By the way, there are various known functional formulas for the formulas (4), (5), and (6) described above, but they are omitted here because they are not particularly related to the new constituent features of the present invention.

Note that if the number of passes must be increased at this time than the previous time, the no-load idle time is again calculated as the shortest time.

FIG. 3 shows changes over time in the rolling speed and rolling mill rotation speed of a reversible rolling mill in which the method of the present invention was implemented. The arrow 31 indicates the start of the first pass of biting rolling, the arrow 32 indicates the start of acceleration, the arrow 33 indicates the maximum speed, that is, the rolling speed, the arrow 34 indicates the start of deceleration, the arrow 35 indicates disengagement and the end of rolling, and the arrow 36 indicates the start of reverse rotation.
The arrow 37 indicates the start of the second pass of biting and rolling. In this embodiment, the time from the end point 35 of the separation rolling to the start point 36 of the reverse rotation can be varied in, for example, three steps, and this time is the same for each pass and cannot be changed. Note that the relationship between the no-load idle time and the reverse rotation start timing (reverse rotation start point) will be explained here.

Typically, the rolling speed of a reversible rolling mill is determined by the joint operation of a rolling roll and table rollers placed before and after the rolling roll. For example, even if the rolling roll is rotating, the rolling speed will be zero if the table rollers placed before and after it are stopped.

The state of zero rolling speed as in this example is the no-load idle time, and this no-load idle time is
Theoretically, there is no special correlation between the timing of the start of reverse rotation due to the cooperative operation of the rolling roll and the table rollers placed before and after the rolling roll.

However, in the actual operation of a reversible rolling mill,
Since the stopping position of the rolled material for each pass is substantially constant, the delay time of the reverse rotation start timing becomes approximately the increase time of the no-load idle time. For example, in the example shown in FIG. 3, the time between the first pass's disengagement 35 and the second pass's engagement 37 is the no-load idle time.

The cumulative power curves for each of the three stages described above are approximately expressed as shown in FIG. Curve 41 is the case when the idle time is the shortest, and curves 42 and 43 are when it is lengthened by Δt and 2Δt. Plate thickness 44 is the initial plate thickness,
The plate thickness 45 is the target plate thickness, and the power value at the intersection of the line of the plate thickness 45 and each curve is approximated to the required total power. This determines the number of passes and the target thickness for each pass, and calculates the necessary rolling schedule.

Here, the method for determining the above-mentioned rolling schedule will be summarized. First, the hardness of the material to be rolled, the temperature and plate thickness of the material to be rolled on the inlet side of the rolling machine, the plate width, the plate length, the target plate thickness and target temperature on the outlet side of the rolling machine, the temperature of the roll cooling water, and the roll diameter. From the rolling specifications, the value of the total power required to roll from the initial plate thickness to the target plate thickness is determined. Note that the value of the total power value does not depend on all of the above rolling specifications, but also depends on the hardness of the material to be rolled, the temperature of the material to be rolled on the entry side of the rolling mill, the width and thickness of the material, and the target on the exit side of the rolling mill. Approximately determined by the plate thickness. This means that in Fig. 4, when the target plate thickness is 45,
The total power is determined as 46 from the rolling power curve 41 at the shortest no-load idle time.

The provisional minimum number of passes is determined from this total power value and the maximum allowable rolling power value determined by the specifications of the rolling mill. The rolling speed and reverse rotation start timing that result in the shortest rolling time for this minimum number of passes are calculated.

Next, the root mean square value of the required rolling power in the shortest rolling time is calculated from the required rolling power in each pass, the required power at times other than rolling (no load), the required rolling time, and the no-load idle time.
It is checked whether this root mean square value of power required for rolling is within the tolerance range of the rolling mill, and if it is within the tolerance range, that value is set as the value of the optimum schedule.

In this case, the initial value of the no-load idle time is the time from the start of rotation of the rolling rolls to the start of rolling. However, if this time is extremely longer than the no-load idle time during normal rolling operation,
It is also conceivable to give the average no-load idle time during normal rolling operation as a constant as an initial value.

If the root mean square power required for rolling is outside the tolerance range of the rolling mill, the value of the no-load idle time is increased, for example, by Δt, and the total power is recalculated. From the rolling power curve 42 in this case, the total power is determined as 47. Recalculate the minimum number of passes at this time,
If it is the same as the provisional minimum number of passes obtained last time,
The root mean square value of the required rolling power is calculated based on the value of this no-load idle time, and the above calculation is repeated until the root mean square value of the required rolling power falls within the tolerance range of the rolling mill. Then, set the value that falls within the allowable range.

If the minimum number of passes obtained by the recalculation becomes larger than the provisional minimum number of passes obtained last time, the rolling speed and reverse start timing that will result in the shortest rolling time for the recalculated minimum number of passes are recalculated. Calculate; repeat the calculation using the value of the no-load idle time based on the rolling speed that results in the shortest rolling time and the reverse rotation start timing until the root mean square value of the required rolling power falls within the allowable range.

Through the above calculation, a rolling schedule that satisfies both the allowable rolling power and the root mean square value of the allowable rolling power is determined.

FIG. 5 shows an example of an apparatus for carrying out the present invention, and parts given the same reference numerals as in FIG. 1 are the same parts as in FIG. 10 sets set values determined for each pass in the rolling down control device 6, the drive motor control device 5, and the roller table drive control device 9;
and a setting control machine that performs start-up control; 11 is a calculation device; the optimum rolling schedule is determined by the number of passes, load distribution, and various tolerance values of the rolling mill; these are calculated to determine the setting values for each pass; This is what we seek. This calculation is obtained by repeating the calculation so that each calculation value, that is, the root mean square of the rolling power, the rolling power, etc., is equal to or less than the allowable value.

As described above, the present invention calculates a rolling schedule that satisfies both the allowable rolling power and the root mean square of the allowable rolling power and minimizes the rolling time by varying the no-load idle time. Since the rolling process is controlled using , rolling can be performed most efficiently.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a conventional reversible rolling mill;
The figure is a rolling power curve diagram for explaining the method of setting the rolling schedule, Figure 3 is a speed time curve diagram in an embodiment of the present invention, and Figure 4 is a change in no-load idle time in an embodiment of the present invention. FIG. 5 is a diagram showing an example of a rolling power curve and a configuration diagram showing an example of an apparatus for carrying out the present invention. In the figure, 1 is a reversible rolling mill, 2 is a material to be rolled, 3 is a rolling roll, 4 is a drive motor, 5 is a drive motor control device, 6 is a rolling roll reduction control device, 7 is a rolling force measuring device, and 8 is a rolling force measuring device. 9 is a table roller drive control device, 10 is a setting controller, and 11 is a calculation device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. From the rolling specifications of the hardness of the material to be rolled, the temperature of the material to be rolled on the inlet side of the rolling machine, the width and thickness of the material, and the target thickness on the exit side of the rolling machine, the target thickness can be calculated from the initial thickness. Find the value of the total power required to perform rolling until Calculate the rolling speed and reversal start timing that result in the shortest rolling time; calculate the shortest rolling time from the required rolling power in each pass, the required power at times other than rolling (no load), the required rolling time, and the no-load idle time. Calculate the root mean square value of the required power for rolling; Check whether the root mean square value of the required power for rolling is within the tolerance range of the rolling mill; If it is within the tolerance range, set that value as the value of the optimal schedule. ; If the above-mentioned root mean square power required for rolling is outside the tolerance range of the rolling mill, increase the value of the no-load idle time and calculate the total power value based on that value; recalculate the minimum number of passes using the above calculation method. If it is the same as the provisional minimum number of passes obtained last time, calculate the root mean square value of the rolling power required based on the value of the no-load idle time; Repeat the above calculation until the number of passes is within the allowable range; If the minimum number of passes obtained by the recalculation is larger than the provisional minimum number of passes obtained last time, the shortest rolling time at the recalculated minimum number of passes Recalculate the rolling speed and reversal start timing that result in the shortest rolling time; Using the value of the no-load idle time based on the rolling speed that results in the shortest rolling time and the reversal start timing, repeat the above steps until the root mean square value of the required rolling power falls within the allowable range. A method for controlling a reversible rolling mill, comprising: repeating the calculation; and controlling a rolling process using a rolling schedule that satisfies both the allowable rolling power and the root mean square value of the allowable rolling power obtained as the above results.