JP6037995B2 - Estimation method of stand tension in strip rolling - Google Patents

Description

  The present invention relates to an estimation method for accurately estimating a stand tension in a bar rolling for rolling bar steel.

Conventionally, in steel bar rolling, which manufactures steel bars (steel bars) such as wire rods, bar bars, and steel bars, rolling is performed while measuring the tension between rolling stands that roll the rolled material that is the source of the bar bars (referred to as inter-stand tension). The material is rolled. In such bar rolling, there are techniques shown in Patent Documents 1 to 5 as techniques for obtaining tension between stands.
In Patent Document 1, the passage of the last end of the strip material (rolled material) in each stand is detected, and while the last end exists in the i-th stand through which the last end has passed and the next i + 1th stand, the strip material is present. The width dimension fluctuation value is obtained, and the tension is obtained from the width dimension fluctuation value and the influence coefficient of the width of the strip. That is, in Patent Document 1, the tension between the stands is estimated from the change in the width dimension of the rolled material when the rolled material falls out.

In Patent Literature 2, the tension between the stands at each time of the tip of the rolled material, the center of the rolled material, and the tail end of the rolled material is estimated from the amount of change in the load and torque of the rolling stand. In Patent Document 3, the tension between the stands is estimated from the load of the rolling stand when the rolled material falls out, the torque of the rolling stand, and the width of the rolled material.
Moreover, in patent document 4, the change of the electromagnetic characteristic by tension | tensile_strength is detected and the tension | tensile_strength between stands is estimated.

Moreover, in patent document 5, while calculating | requiring the change of rolling torque from the rolling load of a rolling stand, the voltage of a drive motor, and an electric current, tension | tensile_strength between stands is based on the change of rolling torque when a rolling material bites into a rolling stand. Estimated.
In other words, Patent Documents 1 to 5 include a method (Patent Document 1) for estimating the tension between the stands from the width dimension of the rolled material when the rolled material slips through, and a rolling model based on the rolling load and rolling torque. A method (Patent Documents 2, 3, and 5) for estimating the tension between the stands by using the method and a method (Patent Document 4) for estimating the tension between the stands by a change in electrical property due to the tension are disclosed.

Japanese Patent Publication No. 5-41334 Japanese Patent No. 2510090 Japanese Patent Publication No. 8-4813 JP-A-6-94547 Japanese Patent Publication No. 4-8124

  In rolling a steel sheet, when a certain amount of rolled material is rolled, the rolling roll is replaced for reasons such as roll wear and rough skin. On the other hand, in a rolling line for producing strip rolling, different from a rolling line that rolls steel sheets, etc., not only rolling rolls but also rolling stands are frequently exchanged depending on the size and shape of the rolled material. . For this reason, it is necessary to repeatedly remove, reattach, and adjust (calibrate) the load cell for measuring the rolling load with replacement of the rolling stand. In order to make the measurement with the load cell accurate, it is necessary to make adjustments and calibrations after the load cell has been attached. For this reason, it is difficult to measure the rolling load using a load cell and obtain the inter-stand tension from the obtained rolling load in the strip rolling line. In addition, for the same reason, it is difficult to accurately calculate the rolling torque from the measured value by the load cell and obtain the inter-stand tension from the obtained rolling torque.

In other words, Patent Documents 2, 3, and 5 disclose that the tension between stands is obtained using a rolling load and a rolling torque. However, obtaining the tension between stands using these techniques is an actual site. In many cases, it is extremely difficult.
On the other hand, Patent Document 1 discloses a technique of a residual tension estimation method for estimating a tension based on a width dimension of a rolled material when the rolled material slips through. However, in the upstream rolling stand in the actual steel bar rolling, the change in tension at the bottom does not significantly affect the change in the width dimension of the rolled material, and the width dimension of the rolled material as in the technique of Patent Document 1. It is difficult to obtain the tension between the upstream stands based on the above.

  Further, Patent Document 4 discloses that the tension between the stands is obtained by a change in electromagnetic characteristics, but the rolled material has a temperature unevenness (for example, a portion in contact with the skid is at a lower temperature than other portions). ), And the electromagnetic characteristics change due to the influence of this temperature unevenness. Therefore, even if the technique of Patent Document 4 is used, the tension between the stands cannot be obtained stably.

  Then, an object of this invention is to provide the estimation method of the stand tension | tensile_strength in the strip rolling which can obtain | require the stand-to-stand tension stably in view of the said problem.

In order to achieve the above object, the present invention takes the following technical means.
That is, the method of estimating the stand tension in the present invention is based on the motor current of the rolling stand when performing strip rolling while measuring the tension between the rolling stands by a rolling mill having a plurality of rolling stands driven by a motor. A low-pass filter process is performed, a difference current that is a change amount of the current value after the low-pass filter process is obtained, and a tension between the rolling stands is obtained using the obtained difference current and the rolling model . The i-th rolling before the rolling material bites into the i + 1-th rolling stand when determining the tension between the rolling stand and the i + 1-th rolling stand located downstream of the i-th rolling stand. Rolling material bites into the stand motor current that has been low-pass filtered and the i + 1th rolling stand. The difference current between the motor current of the i-th rolling stand after being subjected to low-pass filter processing is obtained, and the difference between the rolling stands is determined using the obtained difference current and the following rolling model. It is characterized by calculating | requiring the tension | tensile_strength .

Preferably, the period for obtaining the difference current is 0.5 seconds or less.
Preferably, the deformation resistance is estimated based on the motor current, and the tension between the stands is obtained based on the estimated deformation resistance.
Preferably, the cut-off frequency in the low-pass filter process is 0.2 to 1.0 Hz when the rolling material conveyance speed is 0 to 6 m / sec, and is 0 when the rolling material conveyance speed is 10 m / sec or more. When the feed rate of the rolled material is 6 to 10 m / sec, the cut-off frequency may be selected from the range of 0.2 to 1.0 Hz or 0.5 to 2.0 Hz.

Preferably, when the low-pass filter process is performed, the process may be performed so that the current value data is traced back to the past current value data.
Preferably, n = 2 / f _c point component with respect to the current value data after low-pass filtering (Note, f _c is the cutoff frequency) by using the data has proceeded only the phase, it may determine the difference current.
Preferably, a recursive filter is used as the low-pass filter process.

  According to the present invention, when performing strip rolling by a rolling mill having a plurality of rolling stands, the tension between the stands can be obtained stably at a very low cost without incurring a maintenance cost by the motor current of the motor that drives the rolling stand. .

It is a schematic diagram of the rolling line of a strip steel wire. It is a figure which shows the relationship between the biting condition of a rolling material, and a motor current. It is the figure which showed the time transition of the motor current. It is the figure which showed the detection result of the difference electric current between rolling stands, and the calculation result of tension | tensile_strength. It is the figure which showed performing the detection of the difference electric current between rolling stands after performing a filter process. It is the figure which showed the cutoff frequency and the electric current value before and behind a filter (linear velocity 0.52 m / sec). It is the figure which showed the cutoff frequency and the electric current value before and behind a filter (linear velocity 3.5m / sec).

Before describing embodiments of the present invention, reference embodiments will be described with reference to the drawings.
[Reference embodiment]
FIG. 1 shows an outline of a rolling mill (rolling line) for rolling bar steel (steel bar material) such as bar steel, wire rod, and shape steel.

  The rolling mill 1 rolls a rolled material (raw material) 3 transferred from a heating furnace 2 into a strip, and comprises a rough rolling mill 4, an intermediate rolling mill 5, a finish rolling mill (block mill) 6, a pinch roll 7 A winding machine (laying head) 8 or a cutting device (cold shear) and a cooling bed are provided. A rough rolling mill 4 is disposed on the downstream side of the heating furnace 2, and an intermediate rolling mill 5, a finish rolling mill 6, a pinch roll 7, and a winder 8 are sequentially disposed from the rough rolling mill 4 toward the downstream side. ing.

  Each rolling mill 4, 5, 6 includes a plurality of rolling stands 9. Each rolling stand 9 includes a rolling roll 10, and the rolling roll 10 is provided with a motor (not shown) that rotationally drives the rolling roll 10. The current (referred to as motor current) of the motor that rotationally drives each rolling roll 10 can be detected by current detection means 12 configured by an ammeter or the like, and the detected motor current is controlled by a control device 11 configured by a process controller. To be input.

The control device 11 includes tension calculation means 13 for obtaining the tension between the stands from the motor current, the motor voltage, the motor rotation number, and the like, and drives each rolling roll 10 with the tension between the stands obtained by the tension calculation means 13. The gap of the motor and the rolling roll 10 can be controlled.
In order to roll the rolled material 3 into a strip using such a rolling mill 1, first, the rolled material 3 such as a billet is heated in the heating furnace 2, and then the heated rolled material 3 is subjected to a roughing mill. 4. Introduced in the order of the intermediate rolling mill 5 and the finishing rolling mill 6, the cross section of the rolled material 3 is deformed in the order of square, oval, and round by a caliber provided on the rolling roll 10, and the rolled material 3 is formed in a desired shape. Use a cross-sectional shape. The rolled material that has become the long bar by the finish rolling mill 6 is wound around the winder 8. In this strip rolling, when the rolled material 3 is caught in the rolling stand 9, the inter-stand tension between the rolling stand 9 and the immediately preceding (one upstream side) of the rolling stand 9 is obtained. Control of bar rolling based on the inter tension.

Hereinafter, the tension estimation method performed by the tension calculation means 13 provided in the control device 11 will be described in detail.
FIG. 2 shows the relationship between the biting of the rolled material 3 and the motor current.
As shown in FIG. 2 (a), before the rolled material 3 bites into the i-th rolling stand 9, the motor current of the i-th rolling stand 9 is very close to zero. As shown in FIG. 2 (b), when the rolled material 3 bites into the i-th rolling stand 9, the motor current of the i-th rolling stand 9 increases rapidly. Then, as shown in FIG. 2 (c), the rolled material 3 is caught in the i + 1-th rolling stand 9 which is the next rolling stand 9, and between the i-th rolling stand 9 and the i + 1-th rolling stand 9. When the tension between the stands is generated, for example, the motor current of the i-th rolling stand 9 is further increased.

Thus, since the tension between the stands and the motor current are related, in the present invention, when the tension calculating means 13 obtains the tension between the stands, each motor current for driving each rolling stand is used. Yes.
In order to obtain the tension between the rolling stands, first, as shown in FIGS. 2B and 2C, after the rolled material 3 is bitten into the i-th rolling stand 9, before it is bitten into the i + 1-th rolling stand 9. The motor current in the i-th rolling stand 9 until is detected by the current detection means 12, and this motor current is sequentially stored. For convenience of explanation, the motor current detected after the rolled material 3 “after biting into the i-th rolling stand 9 and before biting into the i + 1-th rolling stand 9” is referred to as “pre-motor current”.

  Next, as shown in FIG. 2 (c), after the rolled material 3 has bitten into the (i + 1) -th rolling stand 9, the motor current of the i-th rolling stand 9 is similarly detected by the current detection means 12. The motor current is stored sequentially. For convenience of explanation, the motor current detected after the rolling material 3 “after biting into the i-th rolling stand 9 and after biting into the (i + 1) -th rolling stand 9” is referred to as “post-motor current”. That's it.

Then, the tension calculation means 13 provided in the control device 11 obtains a difference current that is a difference between the front motor current and the rear motor current. Then, the obtained differential current is applied to the rolling model, and the stand tension between the i-th rolling stand 9 and the i + 1-th rolling stand 9 is obtained.
Hereinafter, the calculation of the tension between the stands will be described in detail using three rolling stands as an example with reference to FIG.

  FIG. 3 (a) shows the change in motor current of the first rolling stand 9, and FIG. 3 (b) shows the change in motor current of the second rolling stand 9. FIG. 3C shows a change in motor current of the third rolling stand 9. For convenience of explanation, the first rolling stand 9 is called a first rolling stand, the second rolling stand 9 is called a second rolling stand, and the third rolling stand 9 is called a third rolling stand.

  When the rolling of the rolled material 3 starts, the motor currents in the first to third rolling stands 9 are measured by the current detection means 12, and each motor current is input to the control device 11. When each motor current exceeds a predetermined threshold, rolling is started. For example, as shown in FIG. 3A, in the first rolling stand 9, since the motor current suddenly increases at the point A and exceeds the threshold value, the control device 11 has the first rolling stand 9 at the point A. It is detected that rolling has started. Similarly, the start of rolling of the second rolling stand 9 is detected at point B, and the start of rolling of the third rolling stand 9 is detected at point C.

Next, the tension calculating means 13 proceeds to a process for obtaining a difference current between the motor currents.
First, as shown in FIG. 3A, after the rolling of the first rolling stand 9 is started, the previous motor current in the first rolling stand 9 is sequentially changed every sampling time until the second rolling stand 9 starts rolling. Remember. Then, after the second rolling stand 9 starts rolling (point B at which the rolled material 3 is caught in the second rolling stand 9), the first rolling stand is kept until the rolled material 3 is caught in the third rolling stand 9. The post motor current at 9 is sequentially stored every sampling time.

That is, the motor current before and after the point B where the rolling material 3 is bitten into the second rolling stand 9, that is, the motor current before the first rolling stand 9 and the motor current after the first rolling stand 9 are expressed. Remember.
When the storage of the front motor current and the rear motor current of the first rolling stand 9 is completed, the tension calculating means 13 calls the data of the front motor current in the first rolling stand 9 and starts from the point B for a few seconds (for example, 2 The previous motor current which is stable in the data traced back in seconds) is set as the first current value Ib for calculating the difference current. Similarly, the tension calculating means 13 calls the post-motor current of the first rolling stand 9 and sets the post-motor current that is stable in the data advanced for several seconds (for example, 2 seconds) from the point B to the differential current. Is a second current Ia for calculating. In other words, a current value that is stable in a section retroactive for a few seconds from point B in the previous motor current is adopted as the first current value Ib, and a few seconds from point B in the rear motor current is advanced. A current value that is stable in the section is adopted as the second current value Ia.

Then, a difference current of the first rolling stand 9 is obtained by subtracting the first current value Ib from the second current value Ia (difference current = Ia−Ib).
When the rolled material 3 is caught in the rolling stand 9, a large current fluctuation (impact) occurs. As described above, when the difference current is obtained, the motor is several seconds before and after the point B (for example, 2 seconds). Since the current is used, the difference current in a portion excluding a large current fluctuation (impact) can be obtained.

  In addition, when calculating | requiring a difference electric current, when the rolling speed is slow, the 1st current value Ib and the 2nd current value Ia which are employ | adopted are good also as an average value of about 0.5 to 1 second in a motor current, and rolling speed If this is early, an average value of about 0.1 to 0.5 seconds in the motor current may be used. For this reason, in each rolling stand 9, the period for obtaining the difference current is preferably 0.5 seconds or less.

  As described above, in obtaining the inter-stand tension between the first rolling stand 9 and the second rolling stand 9, first, the first rolling stand 9 before and after the rolling material 3 bites into the second rolling stand 9. Difference current (= Ia−Ib). Similarly, in obtaining the inter-stand tension between the second rolling stand 9 and the third rolling stand 9, the difference current of the second rolling stand 9 before and after the rolling material 3 bites into the third rolling stand 9 is obtained. I am going to do that.

Then, the inter-stand tension Δσ _F is calculated by the equation (1) based on the obtained difference current ΔA.

The motor torque G used in equation (1) may be calculated by equation (2).
In the case of this embodiment, the deformation resistance kfm used in the calculation of the expression (2) is determined by a person skilled in the art from the actual values of the roll rotation speed N and the motor load (motor current A × motor voltage V) in a state where no tension is applied. This is estimated using a law deformation resistance model (for example, Equations (3) to (5)). That is, the deformation resistance kfm is estimated based on the motor current A, and the tension between the stands is obtained based on the estimated deformation resistance kfm.

Now, the derivation method of the above-described formula (1) is as follows.
First, the relationship among the torque G, voltage V, and current A acting on the motor is expressed as shown in Equation (6).

  When this equation (6) is modified, equations (7) and (8) are obtained.

By using the equations (7) and (8), the inter-stand tension can be obtained by obtaining the difference current (current change amount) when the inter-stand tension is applied. Where σ _F is the front tension and σ _B is the rear tension.
Here, even if a forward tension is generated in the rolling stand, the rear tension is kept constant (even if the rolling material 3 is caught, it does not affect the tension between the already-held stands, that is, Δρ _B = 0) Assuming that the roll gap does not change even when the rolling load changes due to the generation of tension between the stands, that is, assuming that Δh = 0, equations (7) and (8) for obtaining the tension between the stands ) Can be transformed into equation (1).

By calculating the forward tension Δσ _F from the difference current ΔA using the formula (1) thus obtained, the inter-stand tension can be obtained.
FIG. 4 is a diagram showing a result of detecting a difference current between rolling stands and calculating a tension.
In FIG. 4, the i-th rolling stand is represented by “# 1 stand” and the i + 1-th rolling stand is represented by “# 1 + 1 stand”.

As shown in FIG. 4, when the rolled material 3 bites into the i-th rolling stand 9, the motor current of the i-th rolling stand 9 rapidly increases. When the rolled material 3 bites into the (i + 1) -th rolling stand 9, the motor current of the i-th rolling stand 9 slightly increases. Then, when the difference current is detected and the inter-stand tension is obtained when the time exceeds 20 seconds, the inter-stand tension is 0.5 kg / mm ² . In addition, after the rolling material 3 slips through and the first rolling (one pass) is completed, in the second rolling (two passes), when the rolling material 3 bites into the i-th rolling stand 9 (the next material is # 1 stand biting), the tension between the stands (0.15 kg / mm ² ) when the next material is rolled in the vicinity of 75 seconds can be obtained.

As described above, by determining the tension between the rolling stands using the difference in motor current between the adjacent rolling stands and the rolling model, the tension between the stands can be determined stably and accurately.
Embodiment of the present invention
Based on the reference embodiment described above, an embodiment of the present invention will be described below with reference to the drawings.

As described in the reference embodiment, when rolling the steel bar while measuring the tension between the rolling stands 9 by the rolling mill 1 having a plurality of rolling stands 9 driven by a motor, the amount of change in the motor current of the rolling stand 9 is By obtaining the tension between the rolling stands 9 and 9 using a certain difference current and a rolling model, it becomes possible to obtain the tension between the stands stably at a very low cost without incurring a maintenance cost.

However, it has been found that when the technique of the reference embodiment is actually applied to the field, some problems as described below occur.
That is, the actual measured value of the motor current in the field is as shown in FIG. 4A described above. For example, the current measured by the current detecting means 11 has various noises. When a current difference is detected using the measured current (raw current value), a situation occurs in which the tension cannot be detected correctly.

  Therefore, in the present embodiment, the time series data of the measured motor current is subjected to filtering, and is superposed on the time series data of the motor current due to motor resonance, temperature fluctuation of the hot steel, crop cut, and the like. Try to remove various noises. The method disclosed in the reference embodiment is applied to the current value data after filtering, that is, the current data after noise removal, to calculate the inter-stand tension. Such processing is performed by the tension calculating means 13.

  The filter used in the filter processing is a low-pass filter, and various types of filters can be adopted. In this embodiment, a recursive filter is used. The recursive filter used is shown in [Formula 6].

The data used for the filtering process is time series data of 40 to 250 continuous motor current values. The data sampling period is 0.5 seconds or less, preferably 0.1 seconds or less.
Cut-off frequency _{f c} of the Le Car inclusive filter (low pass filter), the conveying speed of the rolled material 3 (linear velocity) is when the 0~6m / sec 0.2~1.0Hz, preferably to 0.5 Hz. When the linear velocity is 10 m / sec or more, it is set to 0.5 to 2.0 Hz, preferably 2.0 Hz. When the linear velocity is between the two, either the cutoff frequency value adopted when the linear velocity is 0 to 6 m / sec or the cutoff frequency value adopted when the linear velocity is 10 m / sec or more. To use.

It is preferable that the cut-off frequency f _c and the above-mentioned range, end the present inventors have conducted intensive studies, be one obtained by finding, sampling period targeting ordinary long products mill 0.1~1sec under the conditions of the above cut-off frequency f _c is an appropriate value.
For example, as shown in (a portion that indicated by circles in particular the drawing) 6, the conveying speed of the rolled material 3 (linear velocity) is in the case of the order of 0.5 m / s, the value f _c of the cut-off frequency Consider a case where a current value is taken in by a rolling stand located on the downstream side at 0.2 Hz to 1.0 Hz. If step-like change of about 100A occurs to the current value 500A had been at around the cut-off frequency f _c is greater than 1 Hz, as step change is gentle on can not be sufficiently remove noise Become. However, the influence of noise is reduced when reducing the cut-off frequency f _c to 0.5 Hz, the cutoff frequency f _c to be sufficiently remove noise when reduced to 0.2 Hz, accurately detectable the stepwise current change It is confirmed that

Further, as shown in FIG. 7 (particularly, the part indicated by a circle in the drawing), when the conveyance speed (linear speed) of the rolled material 3 is about 3.5 m / s, the value f _{c of the} cutoff frequency is set. Consider a case where a current value is taken in by a rolling stand located on the downstream side at 0.2 Hz to 1.0 Hz. If 100A approximately stepwise variation of the current value which has been at around 400A occurs, the cut-off when the frequency f _c is smaller and 0.2 Hz, stepwise changes are Masa Do current value after filtering Variations are no longer measured. However, almost steps when the cut-off frequency f _c to 0.5Hz variation in the current value after the filtering process is to be measured, the current value after filtering by increasing the cutoff frequency f _c until 1.0Hz It has been confirmed that it is possible to confirm changes in the state.

Also, if the i-th rolling stand 9 it is linear velocity (front stand) from the (i + 1) th roll stand 9 (subsequent stand) is fast, taking small cut-off frequency f _c, in (i + 1) th roll stand 9 The applicants of the present application have found that the difference in current cannot be correctly evaluated by “smoothing” the step-like current change accompanying the generation of the tension between the stands due to the biting. In that case, the i + 1 th roll stand 9, it is preferable to set a large cut-off frequency f _c from the i-th rolling stand 9.

  It should be noted that if the cut-off frequency is too high (too high), noise superimposed on the measured current value cannot be completely removed. On the contrary, if the cut-off frequency is too low, the current value (measured current value) that changes stepwise by the rolling material 3 biting into the next stand becomes a gentle change, and the current difference cannot be detected. That is, it is preferable to select a cut-off frequency as high as possible within a range where noise can be removed.

  In FIG. 5 (a), the actual measurement data of the current value in the rolling stand 9 is shown by a graph with a mark (graph before the filter). As shown in this graph, when the current reference area before the next stand biting is seen, it can be seen that the motor current value is about 700A. On the other hand, looking at the current reference area after the next stand bites, the motor current value varies from about 950 A to 800 A, and when the difference current is obtained, it is about 250 A to 100 A, and accurate tension measurement is impossible. It has become a situation.

Therefore, the filter processing using the above-mentioned recursive filter is performed on the measured motor current value. The result is a smooth curve (graph after filtering) in FIG. If the current value after the filter is used, the difference current ΔA is calculated to be about 200 A, and it is possible to obtain an accurate tension by using the equations (1) and (2).
By the way, when performing the above-described filter processing, it is preferable to execute the filter processing so that the current data is placed at the head and the data is traced back to the past data in the order of A0, A1, A2,. In addition,
A0: Current current value A1: Current value one sampling period before the present A2: Current value two sampling periods before the present An: Current value n sampling periods before the present

The reason for performing such processing is that in the case of a recursive filter, since the first few points of the data string are rising, there is a possibility that the true data cannot be reproduced. Therefore, if new data that has little influence on detection of the current difference is filtered at the head, an appropriate filtering process can be realized.
In addition, when the filter processing described above is performed, a phase delay occurs in the data (time series data of motor current values). Therefore, it is very preferable to correct this phase delay. Specifically, the cut-off frequency as _{f c, n = 2 / f} c point fraction, may advance the phase of the data after filtering.

FIG 5 (b) smooth curve definitive, to the measured motor current values, performs a filtering process of applying Les car Shiv filter described above, then, n = 2 / f _c point only advanced phase Is. By using time-series data that has been filtered and phase-shifted in this way, the current difference can be reliably detected with reference to the biting timing of the stand and the next stand, and accurate tension can be calculated. It becomes.

  As described above, when rolling the steel bar while measuring the tension between the rolling stands 9 and 9 by the rolling mill 1 having a plurality of rolling stands 9 driven by a motor, the motor current of the rolling stand 9 is low-pass. Applying filter processing, obtaining the difference current that is the amount of change in the current value after the low-pass filter processing, and obtaining the tension between the rolling stands 9 using the obtained difference current and the rolling model, stably and accurately The tension between the stands can be obtained. As a result, false detection of tension between stands and tension hunting can be reduced, which can contribute to improvement in reliability of tension detection.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. In particular, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. Instead, values that can be easily assumed by those skilled in the art are employed.

1 Rolling mill (rolling line)
2 Heating furnace 3 Rolled material 4 Rough rolling mill 5 Intermediate rolling mill 6 Finishing rolling mill 7 Pinch roll 8 Winding machine 9 Rolling stand 10 Rolling roll 11 Current detection means 12 Controller 13 Tension calculation means

Claims (7)

When performing strip rolling while measuring the tension between the rolling stands by a rolling mill having a plurality of rolling stands driven by a motor,
Low-pass filter processing is performed on the motor current of the rolling stand, a difference current that is the amount of change in the current value after the low-pass filter processing is obtained, and the tension between the rolling stands is determined using the obtained difference current and the rolling model. What we want ,
When determining the tension between the rolling stands between the i-th rolling stand and the (i + 1) -th rolling stand located on the downstream side of the i-th rolling stand, i before the rolling material bites into the i + 1-th rolling stand. The low-pass filter processing was applied to the motor current of the i-th rolling stand after the rolling material bites into the i + 1-th rolling stand. Find the difference current that is the difference from the thing,
A method for estimating stand tension in strip rolling, wherein the tension between the rolling stands is obtained using the obtained difference current and the following rolling model .

The method for estimating a stand tension in strip rolling according to claim 1 , wherein a period for obtaining the difference current is 0.5 seconds or less. The method according to claim 1 or 2 , wherein a deformation resistance is estimated based on the motor current, and a tension between the stands is obtained based on the estimated deformation resistance. Cut-off frequency f _c of the lowpass filter process,
When the conveyance speed of the rolled material is 0 to 6 m / sec, 0.2 to 1.0 Hz,
When the conveyance speed of the rolled material is 10 m / sec or more, 0.5 to 2.0 Hz,
Wherein when the conveyance speed of the rolled material is 6~10m / sec, the claims 1-3, characterized by selecting a cut-off frequency in the range of 0.2~1.0Hz or 0.5~2.0Hz The stand tension estimating method in the bar rolling according to any one of the above. The method for estimating the stand tension in the strip rolling according to any one of claims 1 to 4 , wherein when performing the low-pass filter process, the process is performed so as to go back to the past current value data from the current current value data. . N = 2 / f _c point component with respect to the current value data after low-pass filtering (Note, f _c is the cutoff frequency) by using the data has proceeded only the phase, claims, characterized in that for obtaining a difference current The estimation method of the stand tension | tensile_strength in the bar rolling in any one of 1-5 . A recursive filter is used as the low-pass filter process, The stand tension estimating method in the steel bar rolling according to any one of claims 1 to 6 .

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