JPH07185627A - Flying plate thickness changing method for continuous rolling machine - Google Patents

Abstract

PURPOSE:To improve precision by obtaining a draft position and roll speed more precisely in a flying plate thickness changing method which changes plate thickness without stopping a rolling mill in a tandem rolling mill consisting of plural stands. CONSTITUTION:Steps are provided setting a timing at which a flying plate thickness change point passes each stand as a boundary while the flying plate thickness, change point passes from a first stand through the final stand, and schedule calculation is performed at every step, and accurate draft position S and roll speed N for each stand are found at every step, and they are set on each stand as preset values. Rolling with high precision can be performed by performing the rolling of the flying plate thickness change point based on those preset values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem rolling mill having a plurality of stands, and relates to a running strip thickness changing method for changing the strip thickness without stopping the rolling mill.

[0002]

2. Description of the Related Art Conventionally, when rolling a strip-shaped rolled material,
In order to improve the rolling efficiency, it has become mainstream to adopt a method of welding and connecting the coils and continuously rolling without stopping rolling. At this time, since the target strip thickness at each stand is different between the front material coil portion and the next material coil portion with the welded portion (hereinafter, referred to as the run-out point) as a boundary, Each time the point passes through each stand, that is, each time the bite material shifts from the front material portion to the next material portion, it is necessary to sequentially change the rolling position and the roll speed of the stand.

At this time, as for the setting when the running inflection point passes between the stands, the rolling position is changed to the set value for the next material at the time when the running inflection point passes, and the roll speed runs. In the stand where the current material is flowing downstream from the turning point, the setting of the current material is kept, and in the stand where the next material flowing upstream from the running point is flowing,
In order to smoothly change the speed without causing tears or slack in the plate material, the speed ratio between the stands in the setting of the next material was changed one by one as it passed through each stand.

FIG. 13 shows, for example, Japanese Examined Patent Publication No. 53-39383.
It is a figure which shows the conventional rolling schedule change method shown by the gazette. Here, first, the roll speed of the i-th stand when the current material coil is flowing in all the stands in a state before the running inflection point is biting into the first stand is Si (i = 1,
2 ..., n). Finally, the roll speed of the i-th stand when the run-out point passes through the final n-th stand and the next material coil is flowing in all stands is defined as Si '.

When the running inflection point, which is the intermediate state between the above two, is biting into the kth stand, the roll speed of the kth stand is changed to the set value Sk 'of the next material, and the roll speed of the stand downstream from the kth stand is changed. Is the speed ratio of the actual material Sk + 1: Sk + 2: S
k + 3: ......: Speed change rate S of the k-th stand while maintaining Sn
It is set to a value obtained by multiplying k '/ Sk. For example, when the running inflection point bites into the second stand, the roll speed of the second stand is changed from the previous S2 to S2 ', and in the stands after the third stand, from the third stand to S3 respectively.
(S2 '/ S2), S4 (S2' / S2), ..., Sn (S2 '/
Change to S2).

[0006]

In such a conventional method, the schedule calculation using the model is usually
It is performed only for the final stage where the run-out point passes through the final stand and the next material coil is bitten in all the stands in order to obtain the set values of the rolling position and the roll speed for the next material. And at the intermediate stage where the current material is changed to the next material,
The set value in the intermediate state was calculated from the set value for the current material and the set value for the next material by the method described above. Here, the rolling-down position obtained by the schedule calculation for the next material is calculated by setting both the front and rear tensions to the tension set value for the next material.

[0007] Actually, when the running inflection point passes between the stands, the front tension of the stand in which the running inflection point bites is
In many cases, the tension that has been set for the current material is held so that tension fluctuations do not easily occur. Since the front tension in this case is different from the set value for the next material, it is not possible to accurately obtain the predetermined plate thickness, and in order to obtain the predetermined plate thickness accurately, it differs from the rolling position for the next material. I have to make one. In addition, since the rolling position and the front-rear tension change when passing through the running inflection point, the advance rate (the ratio of the roll speed to the difference between the delivery side plate speed and the roll speed) changes, but the conventional method was suitable for the change in the advance rate. Changes in roll speed were not taken into consideration.

The present invention has been made to solve the above-mentioned problems, and it is possible to obtain a more accurate rolling position and roll speed set value even when the running inflection point passes between the stands. It is an object of the present invention to provide a method for changing the running thickness. Moreover, it aims at correcting the amount of change of the roll speed corresponding to the change of the advance rate.

[0009]

[Means for Solving the Problems] Claim 1 according to the present invention
In the method for changing the running plate thickness, a tandem rolling mill consisting of a plurality of stands is used to change the running thickness without stopping the rolling mill. Dividing into a total of n steps with the timing of being bitten into each stand when biting from one stand to the final n-th stand as a boundary, and the exit side plate thickness of each stand (1 to n) every 1 to n steps, Schedule calculation is performed according to various target values such as plate speed and tension, set values of the rolling position and roll speed of each stand are obtained for each step, and these set values are set for each stand.

According to a second aspect of the present invention, there is provided a tandem rolling mill having a plurality of stands, which is a tandem rolling mill for changing the running thickness without stopping the rolling mill. In the above, when the running plate thickness change point is previously bitten from the first stand to the final n-th stand, it is divided into a total of n steps each time it is bitten into each stand, and each step of 1 to n is divided into Schedule calculation is performed according to various target values such as the outlet side plate thickness, plate speed, and tension of the stands (1 to n), and the set values of the rolling position and roll speed of each stand are obtained for each step, and the learning function is used. The schedule calculation is corrected based on the comparison between the set value and the actual measured value, the corrected set value is obtained, and the corrected set value is set in each stand.

According to a third aspect of the present invention, in the traveling plate thickness changing method, the schedule calculation is performed according to the first or second aspect, wherein the pivot stand whose plate speed before and after the plate thickness change is not changed is an arbitrary stand. It was done.

According to a fourth aspect of the present invention, there is provided a traveling plate thickness changing method according to any one of the first to third aspects, wherein an actually measured advance rate is obtained from an actually measured value of the sheet speed and the roll speed, and the actually measured advance rate is used. The schedule calculation is carried out.

According to a fifth aspect of the present invention, the running plate thickness changing method according to any one of the first to fourth aspects is characterized in that the running plate thickness changing point bites into the first stand and then schedule calculation is performed. The rolling position and roll speed of each stand are set for each step.

[0014]

According to the traveling plate thickness changing method of the first aspect of the present invention, the stand-out target plate thickness of each stand until the stand is bitten into a stand having a traveling plate thickness change point and before being caught in the next stand, Based on each stand inter-plate speed, target tension value, etc.
The schedule is calculated to find the optimum rolling position and roll speed setting value at that time. This schedule calculation is
Since the running thickness change point is changed according to the thickness, plate speed, and tension value that changes each time it is bitten into the stand, perform the same number of times as the number of stands including the schedule for the final next material, Each rolling position and roll speed setpoint is calculated.

According to a second aspect of the present invention, in the traveling plate thickness changing method, the schedule calculation is further corrected based on the comparison between the set value and the actually measured value by using the learning function, and the corrected set value is calculated. Ask.

In the traveling thickness changing method according to the third aspect of the present invention, the schedule is calculated by using the pivot stand as an arbitrary stand, so that the setting error can be easily selected.

According to a fourth aspect of the present invention, the method for changing the running plate thickness is such that the schedule is calculated by using the actually measured advance rate.
Reduce the setting error.

According to a fifth aspect of the present invention, the rolling plate thickness changing method does not set the rolling position and the roll speed of each stand in advance for each step, but the running plate thickness changing point is set to the first stand. Schedule is calculated after biting, and the rolling position and roll speed of each stand are set for each step.

[0019]

【Example】

Example 1. In the conventional schedule calculation, all the stands after the running inflection point has passed through the last stand were performed only for the situation where the next material is biting, but in this example, the running inflection point is set for each stand. Even when the vehicle is passing through, the rolling position and the roll speed setting value of the running plate thickness changing portion obtained by the schedule calculation are obtained.

An embodiment using the five stands will be described below as an embodiment of the present invention. 1 to 6, 1 is a current material portion, 2 is a next material portion, 3 is a running inflection point (running plate thickness change point), 4 is a first stand, 5 is a second stand,
6 is a third stand, 7 is a fourth stand, 8 is a fifth stand, and 9 is a tension reel.

From the position of the running inflection point 3, it is divided into six steps as shown in FIGS. Step A (FIG. 1) is a state in which the current material portion 1 is bitten in all the stands 4 to 8 and before the running inflection point 3 is bitten in the first first stand 4. In Step C ₁ (Fig. 2), the running point 3 is the first
It is in a state before it reaches the second stand 5 by being bitten into the stand 4, and the second to fifth stands 5 on the downstream side of the runoff point 3
In Nos. 8 to 8, the actual material portion 1 is engaged, while the upstream first stand 4 is engaged with the next material portion 2.

Similarly, steps Ci (i = 1 to 1)
4) means that the running inflection point 3 exists between the i-th stand and the (i + 1) th stand, and the current material portion 1 is located downstream of the running inflection point 3 from the i + 1th stand, and is located next to the upstream i-th stand. It shows a state in which the material portion 2 is biting. Finally, step B (FIG. 6) is a state in which the running inflection point 3 has passed through the final stand 8 and the next material portion 2 has been caught in all the stands 5-8.

In the figure, V _i ^Z is the i-th stand output side plate speed in step Z (where i = 0 is the first stand input side plate speed), and T _i ^Z is the i-th stand output side tension in step Z. (However, i = 0 is the tension at the first stand entry side)
^Where S _i ^z is the i-th stand rolling position in step Z, and N _i ^Z is the i-th stand roll speed in step Z.

In each step, the tension set value remains the same as the tension set value of the current material between the stands through which the current material portion 1 passes (T _i ^A ), while the stand through which the next material portion 2 passes. In between, the tension set value ( _Ti ^B ) of the next material is changed. In many cases, the setting value of the actual material is left as it is (T _i ^A ) so as to eliminate the tension fluctuation between the stands having the running inflection point 3.

In the case of this embodiment, the plate speed is the final 5th.
The stand 8 exit side plate speed (V ₅ ^A ) is set as a pivot so as to be constant (V ₅ ^A = V ₅ ^B ), and the plate speed on the upstream side of the final fifth stand 8 is a mass flow (plate thickness x The plate speed) is determined to be constant. However, run point 3
At a position between the i-th stand and the (i + 1) th stand, the plate velocity V _i ^A for the current material part 1 is obtained by the mass flow for the current material part 1 and the plate thickness on the i + 1th stand-in side, and the i-th stand is output. The plate thickness of the next material portion 2 on the side is multiplied to obtain the mass flow for the next material portion 2, and the plate speed on the upstream side from the i-th stand is sequentially calculated so that the mass flow becomes constant.
In this way, the predetermined plate thickness on the entrance and exit sides of each stand in each step, the tension set value, and the plate speed are determined.

Next, for each step, the rolling position and the roll speed for each stand are calculated by schedule calculation based on the above predetermined values. For example, by using the predetermined plate thickness, plate speed, and tension in the state of step C ₁ of FIG. 2 as input values, the schedule calculation C ₁ performs the optimum reduction position S ₁ ^{C1 of} each stand and the roll speed at this step C _1. Calculate the set value N ₁ ^C ₁ . Thereafter, in the same manner, the steps C ₂ , C ₃ , C ₄ and B 4
Schedule calculation is also performed for each step.

In this way, the schedule calculation for a total of 5 steps is performed, and each stand pressing position and roll speed set value for each step are calculated. FIG. 7 shows a list of rolling positions and roll speed setting values of each stand obtained by the schedule calculation according to this embodiment.

Regarding the rolling-down position, the i-th stand (i =
Regarding 1 to 4), the set value S _i ^A for the current material portion is held until the running inflection point 3 reaches the i-th stand. When the running inflection point 3 is bitten into the i-th stand, the front tension remains at the tension value T _i ^A for the current material portion, while the rear tension becomes the tension value T _i-1 ^B for the next material portion. It has been changed. The rolling position set value obtained by the schedule calculation Ci based on this state is S _i ^Ci , and this value becomes the tension values T _i ^B and T _i-1 ^B for the next material based on the front and rear tensions. The value is different from the rolling position S _i ^B obtained in the closed state. In the final fifth stand, the running inflection point 3 passes through the fifth stand and the front tension is also changed to the tension value T ₅ ^B for the next material, so the rolling position is also the set value S ₅ for the next material. Change to ^B at once.

With respect to the roll speed, the set value N _i ^A for the current material portion is held until the running point 3 reaches the i-th stand. After the running inflection point 3 is bitten into the i-th stand, the plate speed in the next material portion is sequentially changed every time the running inflection point 3 is sequentially bitten into the downstream stand. By N _i ^B , N _i ^C1 is changed to N _i ^C4 sequentially. In the schedule calculation, since the roll rate is calculated after calculating the advanced rate (the ratio of the roll speed to the difference between the outlet plate speed and the roll speed), the roll speed corresponding to the advanced rate for each step is obtained. Therefore,
It is possible to obtain an accurate roll speed that also incorporates the amount of change in the advance rate for each step. In this way, even for the stage where the running inflection point 3 sequentially passes through each stand, more accurate change in running plate thickness can be performed by obtaining the rolling reduction position and the roll speed by the schedule calculation.

FIG. 8 is a flow chart of the above-mentioned running plate thickness changing method. For step C _i , the target values of the changing plate thickness, tension, and plate speed before the i stand are calculated (Y
1). From the output target plate thickness, plate speed, tension, etc. for each stand, the rolling positions S _j ^Ci , S _j ^B , roll speeds N _j ^Ci , N _j ^B (j = 1 to i) of each stand at step C _i The set value of is calculated (Y2). The above calculation is repeated until i = n (final stand) (Y3), and the obtained schedule calculation result is set for each stand. The actual rolling is executed with this set value.

Example 2. Although the running thickness change method by schedule calculation has been described in the above embodiment, a running thickness change method with a learning function can also be applied to this. FIG. 9 is a block diagram of this embodiment. The schedule calculation function unit 10 has a learning function unit 11 and a result collection function unit 12 added thereto. The performance collecting function unit 12 has a function of collecting performance values such as the thickness, the rolling position, the roll speed, and the rolling force measured by the thickness gauge 13 and the sensors attached to the stands.

After the stand rolling position and the roll speed set values calculated by the schedule calculation function unit 10 are set for each stand, when the running plate thickness is actually changed, the result collection function unit 12 Collect actual values.
The learning function unit 11 compares the calculated value by the schedule calculation function unit 10 with the actual value collected for the calculated value, and the schedule calculation function is performed so that the schedule calculated value is closer to the actual value with high accuracy. Part 1
Modify the models that make up 0.

As an example, the learning coefficient C is calculated from the schedule calculation value X and the actual value X ^* for this X according to the following equation (1), and the calculation value X _n ^C according to the next model is calculated.
There is a learning method in which the learning coefficient C is reflected as in the expression (2) and the value is set as the set value X _n ^S. C = X ^* / X or ^{X * -X --- (1) X} n S = CX n C or ^{_{X n C + C --- (2}} ) In this way, the schedule calculation of the next-fly thickness change Can be made more precise and accurate.

FIG. 10 shows a flowchart of this embodiment. Steps Y1 to Y3 are the same as those in FIG. 8 of the first embodiment. When all the schedule calculation results are obtained, the results are corrected using the learning coefficient learned last time, and the correction result is set as a set value in each stand (Y
4). Next, actual rolling is performed, and the actual values measured by the sensor (sheet thickness, roll speed, rolling position, rolling force, etc.)
Is calculated (Y5), and the learning coefficient is updated based on the comparison between the schedule calculation value and the actual value by the learning function (Y6).
This updated learning coefficient is used in the next rolling.

Example 3. In Example 1, the pivot is used as the final stand, and the plate speed on the delivery side of the final stand is calculated so that it does not change from the current material to the next material. In this case, as shown in Fig. 7, the set value of each stand is not changed until the current material part passes, but the stand in which the next material part is bitten at the run-in point is Since the set value is changed every time the point passes through each stand in sequence, the accuracy of the leading part of the next material may deteriorate due to a setting error or the like.

In this embodiment, for example, even if the pivot is used as the second stand and the second stand output side plate speed is constant from the current material portion to the next material portion, the plate speed between the respective stands can be obtained. Similarly, the schedule calculation can be used to obtain the set value for the running distance change portion.

FIG. 11 shows a list of roll speed setting changes in this case. As you can see from this list,
The number of setting changes for the next material portion is reduced (in FIG. 7, the calculation of the roll speed is 15 times, and in FIG. 11, it is 13 times, which is reduced twice). Further, when the pivot of the first embodiment is the last stand, the roll speed setting change amount of the first stand is large, but when the second stand is the pivot as in this embodiment, the first stand setting change amount is extremely large. However, the amount of setting change of the fifth stand becomes the largest,
Compared with, the setting change amount for one stand is reduced.
Therefore, the accuracy is increased. In this way, even when the pivot is set to an arbitrary stand, the method for changing the running plate thickness by schedule calculation can be similarly applied.

Example 4. In the above examples, in order to obtain the set value of the roll speed by the schedule calculation, the advanced rate of each stand is predicted by the calculation of the model, and the roll speed setting is made from the target plate speed of each stand on the basis of the predicted value. Seeking a value. As another example,
If a major roll 15 capable of actually measuring the plate speed is installed on the exit side of the stand 14 as shown in FIG. 12, it is possible to measure the advanced rate from the measured values of both the exit-side plate speed and the roll speed. Although not shown, the major roll 15 measures the plate speed with an output according to the rotation of this roll. A more accurate roll speed can be obtained by correcting the calculated value of the advanced rate by the schedule calculation based on the measured advanced rate.

There are two cases in which the measured advanced rate can be applied. One of them is the case where the result of the measured advanced ratio is applied to the schedule calculation at the time of rolling of the next transition point to obtain a better calculation result. The other one is Example 6 described later.
As will be explained in Section 2, when the schedule calculation is not done in advance, but the sequential schedule calculation is performed while rolling and the result is sequentially set in the rolling mill, the result of this measured advanced rate is applied to the schedule calculation. The calculation result can be output with higher accuracy.

The stand 14 is a representative of the first to n-th stands, and in practice, the major roll 15 is best provided on the exit side of all the first to n-th stands. Also, it may be provided on any one stand,
Any plural number may be provided. If it is installed in one place, it is better to install it in the final stand.

Example 5. Although the tandem rolling mill including five stands has been described as an example in the first embodiment, it goes without saying that the running plate thickness changing method can be applied to a tandem rolling mill including a plurality of arbitrary numbers of stands.
If it consists of n stands, the step is step C
_{1 to} C _n-1 and step B are divided into a total of n steps, and the schedule calculation is performed n times.

Example 6. In Examples 1 to 3 described above, the schedule calculation was performed in advance and the rolling was carried out by setting the result in each stand. However, if the processing of the calculation function is fast, the schedule is successively applied during rolling. You may make it calculate and obtain a rolling position and a roll speed. In the future, online computing of schedules will be possible due to improvements in the capabilities of computing elements such as microprocessors.

This embodiment will be described with reference to FIG. 8. Step Y4 is moved between steps Y2 and Y3. In this way, the schedule calculation can be performed while actually rolling, and the calculation result can be sequentially set in the rolling mill and rolled.

Further, this embodiment will be described with reference to FIG. 10. Step Y is performed between step Y2 and step Y3.
Move 4 In this way, the schedule calculation can be performed while rolling, and the calculation result can be sequentially set in the rolling mill and rolled, and the rolling result can be reflected in the learning function in steps Y5 and Y6.

In FIG. 10, steps Y4, Y5 and Y6 may be moved between step Y2 and step Y3. In this case, for example, in step C ₁ of FIG. 2, the rolling result at the first stand can be learned in steps Y5 and Y6 and reflected in the next schedule calculation. Since this can reflect the sequential learning function even after step C _{2 in} FIG. 3, it can be immediately applied during rolling of the running thickness change point, and more accurate rolling can be performed.

[0046]

As described above, the first aspect of the present invention is provided.
According to the above, all the running plate thickness change settings in which the running plate thickness change points pass between the stands are also obtained by the schedule calculation, so the rolling force corresponding to the different front / rear tension is calculated for each step, Accurate reduction position according to the rolling force,
Since the roll speed can be calculated, it is possible to roll at an accurate rolling position and roll speed with respect to online thickness change.

According to the second aspect of the present invention, since the set value is corrected by using the learning function, a more accurate set value can be obtained.

According to the third aspect of the present invention, the schedule is calculated by using the pivot stand as an arbitrary stand, so that the selection for reducing the setting error becomes easy.

According to the fourth aspect of the present invention, since the schedule calculation is performed using the actually measured advance rate, the change in the advance rate due to the change in plate thickness or the change in tension due to the passage of the running plate thickness change point is also taken into consideration. Accurate roll speed setting calculation can be performed, and setting error is reduced.

According to the fifth aspect of the present invention, since the running plate thickness change point bites into the first stand, the schedule calculation is performed and the set value is set, so that the set value is not set in advance. It is possible to perform rolling of thickness change points while running online.

[Brief description of drawings]

FIG. 1 is a diagram showing step A in which an existing material coil is flowing according to a first embodiment of the present invention.

FIG. 2 is a diagram showing step C ₁ at the time of biting the first stand for running inflection point according to the first embodiment of the present invention.

FIG. 3 is a diagram showing step C ₂ when the second stand for running inflection point is engaged according to the first embodiment of the present invention.

FIG. 4 is a diagram showing step C ₃ at the time of engaging the third stand for running inflection point according to the first embodiment of the present invention.

FIG. 5 is a diagram showing step C ₄ when the running inflection point fourth stand is engaged according to the first embodiment of the present invention.

FIG. 6 is a diagram showing step B at the time of biting in the final running inflection point fifth stand according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a rolling position and a roll speed setting change value of each stand according to the schedule calculation of each step according to the first embodiment of the present invention.

FIG. 8 is a flowchart of the operation according to the first embodiment of the present invention.

FIG. 9 is a configuration diagram in which a learning function according to a second embodiment of the present invention is added.

FIG. 10 is a flowchart of an operation including a learning function according to the second embodiment of the present invention.

FIG. 11 is a diagram showing a roll speed setting change value of each stand according to the schedule calculation of each step according to the third embodiment of the present invention.

FIG. 12 is a schematic view of a stand to which a major roll is added according to Example 4 of the present invention.

FIG. 13 is a diagram showing a change in rolling schedule at each stand roll speed in the conventional change in running plate thickness.

[Explanation of symbols]

 1 Current material part Secondary material part 3 Runaway point (running plate thickness change point) 4 1st stand 5 2nd stand 6 3rd stand 7 4th stand 8 5th stand 9 Tension reel 10 Schedule calculation function part 11 Learning Functional part 12 Achievement collection functional part 13 Plate thickness gauge 14 Stand 15 Major roll

Claims (5)

[Claims] 1. A running strip thickness changing method for changing a strip thickness without stopping the rolling mill by a tandem rolling mill comprising a plurality of stands, wherein the running strip thickness change point is set in advance from the first stand. When biting into each final n-th stand, each stand is divided into a total of n steps, and each stand (1 to n) is divided into 1 to n steps.
The schedule calculation is performed according to various target values such as the delivery side plate thickness, plate speed, and tension, and the set values of the rolling position and roll speed of each stand are obtained for each step, and these set values are set for each stand. A method for changing the running plate thickness, which is characterized in that 2. A running strip thickness changing method for changing a strip thickness without stopping the rolling mill by a tandem rolling mill including a plurality of stands, wherein the running strip thickness change point is set in advance from the first stand. When biting into each final n-th stand, each stand is divided into a total of n steps, and each stand (1 to n) is divided into 1 to n steps.
The schedule calculation is performed according to various target values such as the delivery side plate thickness, plate speed, tension, etc., and the set value of the rolling position and the roll speed of each stand is obtained for each step, and the set value and the actual measured value are obtained using the learning function. A method for changing the running plate thickness, characterized in that the set value is corrected based on the comparison with, and the corrected set value is set for each stand. 3. The running plate thickness changing method according to claim 1 or 2, wherein the pivot stand whose plate speed before and after the plate thickness change does not change is set as an arbitrary stand for schedule calculation. How to change the running board thickness. 4. The running plate thickness changing method according to any one of claims 1 to 3, wherein a measured advance rate is obtained from measured values of the plate speed and roll speed, and the measured advance rate is used to schedule. A method for changing the running plate thickness, which is characterized in that calculation is performed. 5. The running plate thickness changing method according to any one of claims 1 to 4, wherein the schedule calculation is performed after the running plate thickness changing point is caught in the first stand, and each step is performed. The method for changing the running plate thickness is characterized in that the rolling position and roll speed of each stand are set.