JP5942386B2 - Cold rolling method and metal plate manufacturing method - Google Patents

Description

  The present invention provides, as a rolling oil supply system for supplying rolling oil to a rolling stand of a cold tandem rolling mill, a first rolling oil supply system that circulates and supplies emulsion rolling oil stored in a circulation tank, and the first rolling oil supply. A cold rolling method for rolling using a cold tandem rolling mill provided with a second rolling oil supply system that supplies emulsion rolling oil having a higher concentration than emulsion rolling oil in the system, and metal using the cold rolling method The present invention relates to a method for manufacturing a plate.

  When cold rolling a steel sheet as a rolling material, a lubricating oil (rolling oil) is used as a lubricant for reducing friction generated between the steel sheet being rolled and a roll. The lubricating oil also has a role as a coolant for cooling the roll and the steel plate that have become high temperature due to frictional heat generated during rolling and heat generated by processing. In ordinary cold rolling, emulsion rolling oil (hereinafter also simply referred to as “emulsion”) is used as the lubricating oil. The emulsion refers to a mixed liquid in which rolling oil particles are stably suspended in water. The emulsion is characterized by its concentration and average particle size. The concentration of the emulsion is the ratio of the oil mass in the total mass of the emulsion. An average particle diameter is an average particle diameter of the rolling oil in an emulsion. In addition, a surfactant is added to prepare an emulsion. The addition amount of the surfactant is a predetermined amount indicated by a mass concentration with respect to the rolling oil amount (oil concentration). And after addition of surfactant, the average particle diameter of an emulsion is adjusted by adding the shear with a stirrer and a pump.

The emulsion rolling oil supply method during cold rolling includes a direct oil supply method that does not use the emulsion rolling oil in a circulating manner (direct method) and a circulating oil supply method that performs lubrication and cooling while circulating the emulsion rolling oil (recirculation). Method).
Here, the circulating oil supply system refers to a system in which emulsion rolling oil is used in a circulating manner. In addition, this emulsion rolling oil is usually an emulsion rolling oil in an O / W emulsion state in which the rolling oil is diluted to a concentration of about 1 to 5% by mass and the oil is dispersed in water using a surfactant. This circulating oil supply system includes a supply means for supplying rolling oil for lubrication on the roll bite entry side of each rolling stand and a supply means for supplying the rolling oil for cooling to the rolling roll. The above-mentioned lubrication and cooling are performed with the same emulsion rolling oil.

  On the other hand, in recent years, with the growing global environmental problems and diversifying user needs, cold rolled products are becoming increasingly stronger and thinner (gauge down). In particular, high-speed rolling at 2000 mpm or more is directed to a thin material having a rolled thickness of 0.3 mm or less, which tends to reduce the rolling weight per unit time. However, in this case, lubrication is insufficient in the conventional circulating oil supply system, and the roll called chattering and the torsional vibration of its drive system are an obstacle.

  Conventionally, as a means for eliminating chattering in a high-speed rolling region due to insufficient lubrication, the friction coefficient of a hybrid lubrication system as shown in Patent Document 1 and an adjacent rolling stand as shown in Patent Document 2 is controlled within an appropriate range. The method is known. In the hybrid lubrication method, the direct lubrication method is adopted in parallel with the circulating lubrication method.

Japanese Patent No. 4654724 Japanese Patent No. 3368841

  In the above prior art, the second emulsion rolling oil is supplied from a second system different from the first emulsion rolling oil supplied by the circulating oil supply method, and the supply flow rate of the second emulsion rolling oil is adjusted. This is a technique for adjusting the lubrication state in the downstream and adjacent rolling stands. However, as described in the above prior art, when the flow rate of the second emulsion rolling oil is feedback-controlled so as to obtain the target lubrication state, the control response and flow rate are reflected until the desired lubrication state is reflected. Dead time associated with valve opening response occurs. In particular, in the latter rolling stand where the rolling speed is high, the influence of the response delay due to the dead time becomes significant, so that the occurrence of chattering cannot always be sufficiently eliminated.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a cold rolling technique capable of supporting high-speed rolling in cold tandem rolling provided with a hybrid lubrication system. .

The present inventors diligently studied a technique for suppressing chattering associated with a delay in flow rate control of the second emulsion rolling oil during high-speed rolling using the hybrid lubrication system as described above.
Based on the knowledge that it is necessary to appropriately maintain the balance of the lubrication state in the final rolling stand of the tandem rolling mill that is the source of chattering and the adjacent rolling stand that affects the tension between the rolling stands. The present inventors have concluded that by controlling the supply amount of the second emulsion rolling oil as follows, the balance of the friction coefficient in the two adjacent rolling stands can be appropriately maintained and chattering can be suppressed. It was.

  That is, in one aspect of the present invention, rolling adjacent from the rolling performance in the rolling stand adjacent to the final rolling stand and the supply amount of emulsion rolling oil supplied from the second rolling oil supply system provided on the rolling stand entrance side. The coefficient of friction at the stand and the steel plate surface roughness after rolling are calculated in reverse, and the steel plate surface roughness after rolling is predicted as the supply condition of the second emulsion rolling oil supplied to the final rolling stand entry side. Moreover, the target friction coefficient in the final rolling stand is set from the friction coefficient difference between the preset final rolling stand and the adjacent rolling stand. And the steel sheet surface roughness as a condition for supplying the second emulsion rolling oil supplied from the second rolling oil supply system on the final rolling stand entry side so that the friction coefficient at the final rolling stand becomes the target friction coefficient Based on the above, the feed-forward control of the supply amount of the second emulsion rolling oil is performed.

And in order to solve the said subject, the invention described in Claim 1 in this invention is stored in the circulation tank as a rolling oil supply system which supplies rolling oil to the rolling stand of a cold tandem rolling mill. A first rolling oil supply system that circulates and supplies the emulsion rolling oil; and a second rolling oil supply system that supplies a second emulsion rolling oil having a higher concentration than the first emulsion rolling oil.
From the friction coefficient in the upstream rolling stand located upstream of the final rolling stand and the supply condition of the second emulsion rolling oil supplied to the upstream rolling stand entrance side, the first supplied to the final rolling stand entrance side Predict the supply conditions of the rolling emulsion oil of No. 2,
The second emulsion rolling oil supplied to the final rolling stand entry side so that the friction coefficient of the final rolling stand calculated from the predicted supply condition of the second emulsion rolling oil becomes the set target friction coefficient. Feed-forward control of the supply amount of
The predicted supply condition of the second emulsion rolling oil includes the surface roughness of the rolled material after rolling in the upstream rolling stand as a variable, and the target friction coefficient is a friction coefficient in the upstream rolling stand. Set based on
From the friction coefficient at the upstream rolling stand and the supply flow rate of the second emulsion rolling oil supplied to the inlet side of the upstream rolling stand, the surface roughness of the rolled material after rolling at the upstream rolling stand. The friction coefficient of the final rolling stand is estimated from the estimated surface roughness after rolling.

Next, in the invention described in claim 2 , when the rolling material is caught in the final rolling stand with respect to the configuration described in claim 1 , the friction coefficient at the final rolling stand is estimated, and the estimated final rolling stand is The control amount of feedback control is obtained from the friction coefficient, and the control amount of the feedforward control is corrected by the obtained control amount of feedback control.

Next, in the invention described in claim 3 , in the configuration described in claim 1 or 2 , the target friction coefficient is a friction coefficient between a friction coefficient of the upstream rolling stand and a friction coefficient of the final rolling stand. The absolute value of the difference is set to be 0 or more and 0.01 or less.
Next, invention of Claim 4 manufactures a metal plate by cold-rolling the rolling material used as a metal plate by the cold rolling method of any one of Claims 1-3. The present invention provides a method for manufacturing a metal plate.

According to the first aspect of the present invention, the flow rate control of the second emulsion rolling oil with respect to the final rolling stand entry side is controlled by the friction coefficient at the upstream rolling stand and the second supplied to the upstream rolling stand entry side. Feed forward control is performed based on the supply conditions of the emulsion rolling oil. As a result, the dead time associated with the flow rate control, which has occurred in the feedback control based on the friction coefficient obtained from the state of the final rolling stand, is eliminated, and the balance of the friction coefficient can be adjusted one by one even in the high-speed rolling zone. Become.

As a result, according to the present invention, it is possible to continue to secure an appropriate lubrication state required even when high-speed rolling is performed by a tandem rolling mill having a hybrid lubrication system.
According to the second aspect of the invention, after the rolling material is caught in the final rolling stand and rolling is started, the feedback control and feedforward of the second emulsion rolling oil based on the coefficient of friction at the final rolling stand are performed. By using the control together, chattering can be prevented with higher accuracy.

According to the invention of claim 3 , it is possible to optimize the balance between the friction coefficient at the upstream rolling stand and the friction coefficient at the final rolling stand more reliably.

It is the figure which showed schematic structure of the cold rolling equipment which concerns on embodiment of this invention. It is a figure explaining the structure of the supply control part which concerns on embodiment of this invention. It is a figure explaining the optimal range of the friction coefficient difference which concerns on embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(Constitution)
First, the cold rolling equipment and other configurations will be described.
FIG. 1 is a schematic configuration diagram for explaining a cold tandem rolling mill having a plurality of rolling stands in an embodiment of the present invention. In the present embodiment, a steel plate is taken as an example of the rolled material. The rolled material can be applied to an aluminum plate or other strip.

  The cold tandem rolling mill shown in FIG. 1 rolls five rolling stands from the first rolling stand to the fifth rolling stand (# 1STD to # 5STD) in order from the entry side (left side in FIG. 1) of the rolled material (steel plate) 1. The case of a cold tandem rolling mill having a mill is shown. In this cold tandem rolling mill, tension rolls and deflores (not shown) are appropriately installed between adjacent rolling stands. A rolling stand, a steel plate conveyance device, and the like are not particularly limited.

  Moreover, in this embodiment, two systems, the 1st rolling oil supply system 2 and the 2nd rolling oil supply system 12, are provided as a rolling oil supply system which supplies rolling oil to the rolling stand and steel plate of a cold tandem rolling mill. The first rolling oil supply system 2 circulates and supplies the emulsion rolling oil (first emulsion rolling oil) stored in the circulation tank. On the other hand, the second rolling oil supply system 12 is a direct oil supply system that supplies a second emulsion rolling oil having a higher concentration than the first emulsion rolling oil.

  The first rolling oil supply system 2 is configured by disposing a lubricating coolant header 3 on the entrance side of the rolling stand and a cooling coolant header 4 on the exit side of the rolling stand for each rolling stand. The lubricating coolant header 3 and the cooling coolant header 4 are connected to a circulating rolling oil supply tank 5 via a rolling oil supply line 7. A pump 6 is interposed in the middle of the rolling oil supply line 7. The circulating rolling oil supply tank 5 stores emulsion rolling oil (first emulsion rolling oil) 11 that is used in a circulating manner. Then, the first emulsion rolling oil 11 stored in the circulating rolling oil supply tank 5 is pumped by the pump 6 to the coolant headers 3 and 4 disposed in the rolling stands through the rolling oil supply line 7. Supplied. The first emulsion rolling oil 11 that is circulated is supplied from spray nozzles provided in the respective coolant coolant headers 3 and coolant coolant headers 4.

As described above, the first emulsion rolling oil 11 pumped from the circulating rolling oil supply tank 5 through the rolling oil supply line 7 by the pump 6 is rolled from the lubricating coolant header 3 arranged in each rolling stand. And is supplied from the cooling coolant header 4 toward the work roll.
The supplied first emulsion rolling oil 11 is recovered by a recovery oil pan 8 except for what is taken out of the system by the steel plate 1 or lost by evaporation, and is supplied with circulating rolling oil through a return pipe 9. Returned to the tank 5.

As described above, the first rolling oil supply system 2 includes a circulating rolling oil supply tank 5, a pump 6, a rolling oil supply line 7, a coolant coolant header 3, a coolant coolant header 4, a recovered oil pan 8, and a return pipe 9. The first emulsion rolling oil 11 constituted and supplied by the above is circulated and used.
In addition, it is preferable that the supply to each coolant header 3 and 4 of the 1st emulsion rolling oil 11 using the 1st rolling oil supply system 2 is implemented from the time of the rolling start of a rolling material. As a result, a predetermined rolling oil is supplied to each roll and the steel plate 1.

  Here, the said 1st emulsion rolling oil 11 is formed by mixing the hot water (dilution water) accommodated in the circulation type rolling oil supply tank 5, and rolling oil stock solution. The hot water and the rolling oil stock solution to be mixed are adjusted by adjusting the rotation speed of the stirring blade of the stirrer 10, that is, by adjusting the degree of stirring, so that the first emulsion rolling oil having a desired average particle diameter is obtained. 11.

  As the rolling oil constituting the first emulsion rolling oil 11, those used in normal cold rolling can be applied. That is, as the rolling oil, for example, a base oil made of any of natural fats and oils, fatty acid esters, and hydrocarbon-based synthetic lubricating oils can be used. Furthermore, you may add the additive used for normal cold rolling oil, such as an oil improvement agent, an extreme pressure additive, antioxidant, to these rolling oil.

In addition, as the surfactant added to the rolling oil, either ionic or non-ionic surfactants may be used, as long as those used in a normal circulating coolant system (circulating rolling oil supply system) are used. Good.
And as the first emulsion rolling oil 11, the rolling oil as described above is preferably diluted to a concentration of about 1 to 5% by mass, more preferably about 1.2 to 3.0% by mass. An O / W emulsion in which oil is dispersed in water using such a surfactant is used. The average particle diameter is preferably 15 μm or less, more preferably about 7 to 10 μm.

In the present embodiment, as described above, the second rolling oil supply system 12 is provided separately from the first rolling oil supply system 2. The second rolling oil supply system 12 includes a lubrication nozzle header 23, a flow control valve 22, a supply line 21, a supply pump 20, and an emulsion tank 18.
A stirrer 19 is disposed in the emulsion tank 18. In addition, the rolling oil crude oil tank 14 and the hot water tank 15 are connected to the emulsion tank 18 with respect to the emulsion tank 18. And the rolling oil crude oil stored in the rolling oil crude oil tank 14 and the hot water stored in the hot water tank 15 are fed into the emulsion tank 18 via the pump 16 and the flow rate control valve 17, and It is mixed in the emulsion tank 18 to become the second emulsion rolling oil 13.

  The emulsion temperature conditions in the emulsion tank 18 are preferably the same as the conditions of the first emulsion rolling oil 11. The second emulsion rolling oil 13 in the emulsion tank 18 is adjusted to an average particle size of 15 to 30 μm by adjusting the rotation speed of the stirring blades of the stirrer 19. The emulsion concentration in the emulsion tank 18 is adjusted within a range of 3 to 15% by mass.

  Then, the second emulsion rolling oil 13 in the emulsion tank 18 is sent to the lubrication nozzle header 23 via the supply line 21 and the flow rate control valve 22 by the supply pump 20. The lubrication nozzle header 23 is branched and arranged on both the upper surface side and the lower surface side of the steel plate 1, so that the second emulsion rolling oil 13 having a desired concentration is directed to both the front and back surfaces of the steel plate 1. It is comprised so that injection is possible.

  In the configuration illustrated in FIG. 1, the second emulsion rolling oil 13 injected to the steel plate 1 is recovered in a recovery oil pan 8 as rolling oil recovery and circulation means that constitutes a circulation system. Then, the recovered second emulsion rolling oil 13 is collected in the circulation rolling oil supply tank 5 through the return pipe 9 together with the emulsion rolling oil 11 being circulated and used. It becomes. That is, the recovered emulsion rolling oils 11 and 13 are stirred by the stirrer 10 in the circulating rolling oil supply tank 5 and then sprayed from the spray nozzles of the pump 6 and the lubricating coolant header 3 and the cooling coolant header 4. The strong shearing at the nozzle portion is repeatedly received, and the particles are subdivided to a particle size set as the first emulsion rolling oil 11 to be circulated.

  Here, the cold rolling mill shown in FIG. 1 shows a case where the lubricating nozzle header 23 of the second rolling oil supply system 12 is provided on each entry side of the final rolling stand # 5STD and its adjacent rolling stand # 4STD. ing. The lubricating nozzle header 23 may be provided on the entry side of another rolling stand. The amount of the emulsion rolling oil supplied from the nozzle spray of each lubricating nozzle header 23 is adjusted by an individual flow control valve 22. The adjacent rolling stand # 4STD is a rolling stand located upstream of the final rolling stand # 5STD, that is, upstream.

  Further, the method for adjusting the second emulsion rolling oil 13 sent to the lubricating nozzle header 23 is not limited to the above-described method. For example, as a concentration adjusting means for the second emulsion rolling oil 13, the rolling oil crude oil, the first emulsion rolling oil 11 and hot water are mixed by the nozzle mix method in the immediate vicinity of the lubrication nozzle header 23, and the second The emulsion rolling oil may be used, or the first emulsion rolling oil 11 may be mixed in the emulsion tank 18. Further, as a means for adjusting the particle size of the second rolled emulsion oil 13, a mechanical shearing means such as a static mixer or a gas mixing means is provided in the path where the second emulsion rolled oil 13 reaches the lubricating nozzle header 23. May be.

  In the rolling oil supply facility as described above, the first rolling oil supply system 2 which is a circulating rolling oil supply system is used to bring the steel plate 1 (roll bite) and rolls into the roll-in side and the roll-out side of each rolling stand. The steel sheet 1 and the roll are lubricated and cooled by supplying a relatively low concentration emulsion rolling oil. In addition, in the 1st rolling oil supply system 2, since rolling oil is circulated and used, the basic unit of rolling oil is low.

  Furthermore, in the present embodiment, the second rolling oil supply system 12 that is a direct rolling oil supply system allows the final rolling stand # 5STD, which is a subsequent rolling stand with relatively high rolling speed, and the adjacent rolling stand # 4STD. On each entry side, the second emulsion rolling oil having a concentration higher than that of the first emulsion rolling oil is supplied to the steel sheet 1. The supply of emulsion rolling oil from the second rolling oil supply system 12 eliminates chattering in the high-speed rolling zone due to insufficient lubrication. Suppression of chattering is performed by appropriately maintaining the balance of the lubrication state in the final rolling stand # 5STD and the adjacent rolling stand # 4STD that is affected by the tension between the rolling stands. Specifically, chattering is suppressed by appropriately maintaining the balance of the friction coefficient between the final rolling stand # 5STD and the adjacent rolling stand # 4STD, which are two adjacent rolling stands. The adjacent rolling stand # 4STD refers to the preceding rolling stand adjacent to the final rolling stand # 5STD.

  From the above, it is important to appropriately control the friction coefficient in the final rolling stand # 5STD by controlling the flow rate of the second emulsion rolling oil supplied to the rolling stand entrance side.

Next, a second emulsion rolling oil supply control method using the second rolling oil supply system 12 will be described.
In the present embodiment, the friction coefficient at the adjacent rolling stand # 4STD and the surface roughness of the steel sheet 1 after rolling are estimated, and the estimated steel sheet 1 surface roughness after the adjacent rolling stand # 4STD rolling and the final rolling stand # 5STD are set. By controlling the flow rate of the second emulsion rolling oil supplied to the inlet side of the final rolling stand # 5STD based on the target friction coefficient, the friction between the final rolling stand # 5STD and the adjacent rolling stand # 4STD is controlled. Maintain a proper balance of coefficients. Specifically, the target friction coefficient in the final rolling stand # 5STD is set from the friction coefficient in the adjacent rolling stand # 4STD, and the estimated surface roughness of the steel sheet 1 is supplied to the entrance side of the final rolling stand # 5STD. The second emulsion rolling oil is predicted as a supply condition of the second emulsion rolling oil, and feedforward control is performed on the second emulsion rolling oil supplied to the final rolling stand # 5STD inlet side using the estimated surface roughness of the steel sheet 1 as a variable. Further, in the present embodiment, when the rolling material of interest is caught in the final rolling stand # 5STD and the friction coefficient at the final rolling stand # 5STD can be estimated, the final rolling stand # 5STD A feedback control amount is obtained based on the friction coefficient at, and a process for correcting the control amount of the feedforward control with the feedback control amount is performed.

Hereinafter, adjustment of the friction coefficient by the rolling oil supplied from the second rolling oil supply system 12 will be described in detail.
FIG. 2 is a diagram illustrating a control block of the supply control unit 30 that performs the supply control of the second emulsion rolling oil according to the present embodiment.
As shown in FIG. 2, the supply control unit 30 includes a first friction coefficient reverse calculation unit 31, a post-rolling surface roughness estimation unit 32, a target friction coefficient setting unit 33, a supply flow rate control unit 34, and a second friction coefficient reverse calculation unit. 35, a friction coefficient estimation unit 36, and an FB component calculation unit 37.

  First friction coefficient reverse calculation unit 31 obtains a friction coefficient at an adjacent rolling stand (adjacent rolling stand # 4STD). That is, the friction coefficient at the adjacent rolling stand # 4STD is back-calculated (estimated) from the rolling record at the adjacent rolling stand # 4STD using a rolling model such as Brand & Ford or a friction coefficient model. Similarly, the second friction coefficient reverse calculation unit 35 reversely calculates (estimates) the friction coefficient from the rolling performance in the final rolling stand # 5STD. It is performed when the steel plate 1 is caught in the final rolling stand # 5STD and rolling is started at the final rolling stand # 5STD.

  The relationship between the advanced rate and the friction coefficient and the relationship between the rolling load and the friction coefficient have been clarified by a rolling model such as Bland & Ford, and the friction coefficient can be estimated by using such a relational expression. The friction coefficient model is a model formula showing the relationship between rolling conditions such as rolling material components, sheet thickness, rolling reduction, rolling speed, lubrication, and friction coefficient. For example, statistical data such as multiple regression analysis using actual data is used. It can be created by processing.

The post-rolling surface roughness estimation unit 32 is based on the second emulsion rolling oil supplied on the inlet side of the adjacent rolling stand # 4STD and the friction coefficient at the adjacent rolling stand # 4STD estimated by the first friction coefficient reverse calculation unit 31. The surface roughness after rolling at the adjacent rolling stand # 4STD is estimated.
Here, the oil film thickness h <b> 1 at the adjacent rolling stand is constituted by a roll bite inlet oil film h <b> 11 by the first emulsion rolling oil 11 and a roll bite inlet oil film h <b> 12 by the second emulsion rolling oil 13. Therefore, the oil film thickness can be calculated by the following formulas (1) and (2) that ignore the heat conduction in the oil film in the Reynolds equation.

here,
U ₁ : Material speed (rolling speed of material to be rolled) [mpm]
U ₂ : WR speed (work roll peripheral speed) [mpm]
σ ₀ : material yield stress [kgf / mm 2]
Ld: Contact arc length (projected projection length between the work roll and the material to be rolled) [mm]
R ′: WR (work roll) flat radius [mm]
η ₀ : Viscosity at normal temperature and normal pressure [Pa · s]
α ₁ : Pressure viscosity coefficient [1 / GPa]
β: Temperature viscosity coefficient [1 / ° C]
T _m : coolant temperature [° C]
T ₀ : ambient temperature (= 40 ° C.)
C: Concentration [mass%] of the first emulsion rolling oil 11
d: Average particle diameter [μm] of the first emulsion rolling oil 11
F _trap : trap rate of the first emulsion rolling oil 11 (= 0.3)
H ₁ : Preset coefficient Q: Supply flow rate of second emulsion rolling oil 13 [L / min]
It is.

In general, the friction behavior at the roll bite interface in cold rolling is a mixed lubrication state, and the friction coefficient can be generally expressed by the following equation (3). At this time, it is known that the contact ratio α in (3) can be experimentally expressed by the relational expression (4) between the oil film thickness and the synthetic roughness in the roll bite (Nakajima et al. (1979), A53.).
And the synthetic | combination roughness in an adjacent stand, ie, the steel sheet 1 surface roughness (sigma) after adjacent stand rolling, can be estimated from (3)-(5) Formula using the friction coefficient in an adjacent rolling stand. μb can be determined by the Bowden test. μL may be given as a constant, but is generally about 1/10 of μb.

here,
μ _b : friction coefficient of boundary lubrication part μ _L : friction coefficient of fluid lubrication part α: contact rate

By substituting the supply conditions of the emulsion rolling oil supplied to the adjacent rolling stand # 4STD into the equations (1) and (2), the oil film thickness h1 at the adjacent rolling stand # 4STD can be calculated. By substituting the calculated oil film thickness and the friction coefficient μ ₄ calculated by the rolling model such as Bland & Ford into the equation (5) obtained by modifying the equations (3) and (4), the surface roughness of the steel sheet 1 after rolling Can be estimated.

Further, the target friction coefficient setting unit 33 calculates the friction coefficient difference between the friction coefficient μ ₄ at the adjacent rolling stand calculated by the rolling model such as Bland & Ford and the friction coefficient difference between the preset final rolling stand # 5STD and the adjacent rolling stand. From the absolute value, the target friction coefficient at the final rolling stand # 5STD is set.

Here, the absolute value of the friction coefficient difference is preferably set to be 0 or more and 0.01 or less. This is because chattering is likely to occur when the difference between the two friction coefficients exceeds the above range.
FIG. 3 is a graph showing chattering distribution when a hard tin plate having a finishing thickness of 0.2 mm is rolled at a rolling speed of 2000 mpm. It can be seen that chattering is likely to occur under rolling conditions where the absolute value of the difference in friction coefficient between the upstream rolling stand and the final rolling stand is greater than 0.01.

  Further, the friction coefficient estimating unit 36 uses the surface roughness σ of the steel sheet 1 after the adjacent rolling stand # 4STD rolling, and the friction at the final rolling stand # 5STD by the equation (6) obtained by modifying the equations (3) to (4). Predict coefficients.

here,
h ₁ ^* : Oil film thickness [μm] at the final rolling stand # 5STD
r: reduction ratio R ₁ of the final roll stand ♯5STD, R _2: final rolling WR (work roll) in the stand ♯5STD wear coefficient WR _ton: at the final rolling stand ♯5STD WR (in the work roll) rolling weight [Ton]
Note that the prediction of the friction coefficient at the final rolling stand # 5STD is not limited to the above calculation method. For example, the friction coefficient model formula may be created by multiple regression analysis using rolling conditions such as sheet thickness and rolling reduction of the material to be rolled, coolant supply amount, emulsion concentration and particle size, rolling length, rolling speed, etc. .

  The FB component calculation unit 37 calculates a control amount for feedback control. For example, the FB component calculation unit 37 obtains a deviation between the friction coefficient at the final rolling stand # 5STD calculated backward (estimated) by the second friction coefficient reverse calculation unit 35 and the target friction coefficient set by the target friction coefficient setting unit 33. Then, after multiplying the deviation by a preset gain G, a PI (proportional integral) term is calculated to obtain a feedback control amount, and the obtained feedback control amount is output to the supply flow rate control unit 34. The output of the feedback control amount is set when the steel plate 1 is caught in the final rolling stand # 5STD.

  The supply flow rate control unit 34 enters the final rolling stand # 5STD so that the friction coefficient at the final rolling stand # 5STD estimated by the friction coefficient estimation unit 36 becomes the target friction coefficient set by the target friction coefficient setting unit 33. Feed forward control is performed on the supply amount of the second emulsion rolling oil supplied to. The supply amount of the second emulsion rolling oil is controlled by adjusting the opening degree of each flow control valve 22.

  In addition, when there is an input of feedback control amount from the FB component calculation unit 37, the supply flow rate control unit 34 takes into account the feedback control amount, and enters the final final rolling stand # 5STD to the second entry side. Adjust the emulsion feed rate. That is, after the rolling material is caught in the final rolling stand # 5STD and rolling is started in the final rolling stand # 5STD, the control amount of the feedforward control is set to the second based on the inverse friction coefficient based on the final rolling stand # 5STD. It corrects with the control amount of the feedback control of the emulsion rolling oil. As a result, the final rolling stand # 5STD can be controlled with high accuracy.

Here, the combined use of feedback control and feedforward control is performed as follows. The target friction coefficient μset at the final rolling stand # 5STD set by the target friction coefficient setting unit 33, the friction coefficient μ at the final rolling stand # 5STD estimated by the friction coefficient estimation unit 36, and the rolling at the final rolling stand # 5STD The supply flow rate control value Q of the second emulsion rolling oil on the final stand entry side is set by Equation (7) using the friction coefficient μ ₅ calculated backward from the actual results using a rolling model such as Bland & Ford.

here,
G _FF : Adjustment gain of feed forward control G _FB : Adjustment gain of feedback control K _p : Proportional gain of feedback control K _I : Integration gain of feedback S: Integration time.

Β is a constant that varies depending on the rolling speed and the control method. When the rolling speed is zero or only feedforward control is performed, “β = 0”.
Here, in the case where chattering is unlikely to occur, such as rolling with a soft material that does not cause insufficient lubrication, rolling at a low speed rolling, or rolling at an acceleration / deceleration unit, the adjustment of the rolling oil by the feed forward control is performed. You don't have to do it. The same effect can be obtained even if the feedforward control or the feedback control is performed only when the operating conditions are likely to cause chattering.

(Function and effect)
In the present embodiment, from the rolling performance at the rolling stand adjacent to the final rolling stand # 5STD and the supply amount of the second emulsion rolling oil supplied at the inlet side of the adjacent rolling stand # 4STD, The coefficient of friction and the surface roughness of the steel sheet 1 after rolling are calculated by back calculation. Further, the target friction coefficient at final rolling stand # 5STD is set from the absolute value of the difference in friction coefficient between preset final rolling stand # 5STD and the adjacent rolling stand.

  Then, the estimated surface roughness of the steel sheet 1 (the second emulsion rolling oil supplied to the inlet side of the predicted final rolling stand # 5STD is set so that the friction coefficient at the final rolling stand # 5STD becomes the target friction coefficient. Based on the supply conditions), the supply amount of the second emulsion rolling oil supplied to the final rolling stand # 5 STD inlet side is adjusted by feedforward control. Thereby, the balance of the friction coefficient in two adjacent rolling stands is appropriately maintained, and chattering is suppressed.

  At this time, instead of adjusting the supply amount of the second emulsion rolling oil supplied to the inlet side of the final rolling stand # 5STD by feedback control based on the inverse friction coefficient of the final rolling stand # 5STD, in this embodiment, the final rolling stand The supply amount of the second emulsion rolling oil supplied to the final rolling stand # 5STD inlet side is controlled by the feedforward control as described above that does not use the inverse friction coefficient of # 5STD. As a result, the dead time associated with the flow control of the second emulsion rolling oil is eliminated, and the balance of the friction coefficient can be adjusted one by one even in the high-speed rolling region.

  Further, after the rolling material is caught in the final rolling stand # 5STD and rolling at the final rolling stand # 5STD is started, feedback of the second emulsion rolling oil based on the inverse friction coefficient at the final rolling stand # 5STD By adding the control amount by the control to the control amount of the feedforward control, chattering can be prevented with higher accuracy.

  The absolute value of the friction coefficient difference between the final rolling stand # 5STD and the adjacent rolling stand is 0 or more and 0.01 or less. This is because chattering is likely to occur when the difference between the two friction coefficients exceeds the above range.

Hereinafter, the present invention will be described based on examples.
Using a cold tandem rolling mill of all five rolling stands of the embodiment shown in FIG. 1, a target speed is set to a finished thickness of 0.180 mm using a hard tin plate having a base material thickness of 2.0 mm and a plate width of 850 to 950 mm as a rolling material. Rolling was performed at 2200 m / min. For rolling oil, 1% by mass of each of oiliness agent and antioxidant is added to the base oil to which vegetable fats and oils are added based on synthetic ester oil, and nonionic surfactant is used as a surfactant. And 3% by mass added.

  The first emulsion rolling oil 11 supplied from the first rolling oil supply system 2 and used in a circulating manner was adjusted to an emulsion rolling oil having a rolling oil concentration of 3.0 mass%, an average particle size of 9 μm, and a temperature of 55 ° C. On the other hand, the rolling oil crude oil and hot water similar to the above were transferred from the rolling oil crude oil tank 14 and the hot water tank 15 to the emulsion tank 18. At this time, each supply amount was adjusted so that the emulsion concentration in the emulsion tank 18 would be 10 mass%. Next, the mixture contained in the emulsion tank 18 was stirred by adjusting the rotation of the stirring blade of the stirrer 19 to prepare a second emulsion rolling oil 13 having an average particle diameter of 20 μm. In addition, the temperature of the 2nd emulsion rolling oil 13 was made the same with the emulsion rolling oil 11 used cyclically.

In Example 1, the friction coefficients μ ₄ and μ ₅ at each rolling stand were sequentially calculated back from the rolling results at the final rolling stand # 5STD and the adjacent adjacent rolling stand # 4STD using the Brand & Ford rolling model. Next, in the adjacent rolling stand using the formulas (1) to (2) from the actual supply amount of the second emulsion rolling oil supplied from the second rolling oil supply system 12 provided on the rolling stand entry side. The oil film thickness h ₁ was sequentially calculated back. Subsequently, the friction coefficient at the final rolling stand # 5STD was sequentially estimated from the equation (6) by calculating the surface roughness σ of the steel sheet 1 after passing through the adjacent rolling stand from the equation (5).

Then, using the friction coefficient of the adjacent rolling stand # 4STD and the final rolling stand # 5STD estimated from the equation (6), feedforward control (β = 0) based on the control of the equation (7) is performed, and the final rolling stand # 5 The supply amount of the emulsion rolling oil supplied from the second rolling oil supply system 12 on the 5STD inlet side was controlled.
Except that the feedback control using the friction coefficient mu ₅ of feedforward control and the final rolling stand ♯5STD based on the control of this Example 2 (7) were carried out were the same conditions as in Example 1.

Further, in Example 3, the same conditions as in Example 2 were adopted except that the difference between the friction coefficient at the adjacent rolling stand # 4STD and the predicted friction coefficient was controlled to be 0 or more and 0.01 or less. .
The numerical values shown in Table 1 below were used as coefficients other than the rolling conditions used for calculating the friction coefficient.

  Here, as a comparative example, a feedback mechanism using the second emulsion rolling oil described in Patent Document 1 is provided, and the difference in friction coefficient between the rolling stand adjacent to the final rolling stand # 5STD and the final rolling stand # 5STD. The feedback flow control of the flow rate of the second emulsion rolling oil 13 was performed so that the value was within a certain range. Note that the range of the friction coefficient difference was the same as in the example.

  Table 2 shows the actual friction coefficient and the occurrence of chattering in the # 4 rolling stand and the final rolling stand # 5STD when the rolling oil is supplied as described above and high speed rolling is performed. The actual friction coefficient is a value calculated backward from the rolling load and tension at the rolling speed.

In Table 2, ○, Δ, and x indicate the following.
○ ... No chattering occurred △ ・ ・ ・ Mild chattering occurred × ・ ・ ・ Chattering occurred As can be seen from Table 2, in this example, the friction coefficient of the final rolling stand # 5STD is set upstream of the final rolling stand # 5STD. By predicting in advance at the supply position of the second emulsion rolling oil supply process installed in the machine, the friction coefficient difference between the adjacent rolling stands can be immediately adjusted to a certain range, particularly feedforward control. And feedback control in combination, and the difference in the friction coefficient to be controlled was 0.01 or less, no chattering was observed at any rolling speed.

  On the other hand, in the feedback control of the second emulsion rolling oil as in the comparative example, it was possible to control the friction coefficient difference to be within a certain range up to a rolling speed of 1800 mpm. Mild chattering began to occur because the control did not catch up due to the time delay. In addition, severe chattering occurred at a rolling speed of 2200 mpm, and the surface quality of the steel sheet 1 was significantly lowered.

  From the above examples, by using the lubricating oil supply method according to the present invention, it is possible to keep the coefficient of friction in the subsequent rolling stand within an appropriate range even in high-speed rolling using the hybrid lubrication method, which is stable. It was confirmed that high productivity and a good steel plate 1 shape can be obtained.

1 Steel plate (rolled material)
2 1st rolling oil supply system 3 Lubricating coolant header 4 Cooling coolant header 5 Circulating rolling oil supply tank 6 Pump 7 Rolling oil supply line 8 Collected oil pan 9 Return pipe 10 Stirrer 11 First emulsion rolling oil 12 2nd Rolling oil supply system 13 Second emulsion rolling oil 14 Rolling oil crude oil tank 15 Hot water tank 16 Pump 17 Flow rate control valve 18 Emulsion tank 19 Stirrer 20 Supply pump 21 Supply line 22 Flow rate control valve 23 Lubrication nozzle header 30 Supply control unit 31 1 Friction coefficient reverse calculation part 32 Rolled surface roughness estimation part 33 Target friction coefficient setting part 34 Supply flow rate control part 35 Second friction coefficient reverse calculation part 36 Friction coefficient estimation part 37 FB component calculation part

Claims (4)

As a rolling oil supply system for supplying rolling oil to a rolling stand of a cold tandem rolling mill, a first rolling oil supply system that circulates and supplies a first emulsion rolling oil stored in a circulation tank, and the first emulsion rolling oil A second rolling oil supply system for supplying a second emulsion rolling oil having a higher concentration,
From the friction coefficient in the upstream rolling stand located upstream of the final rolling stand and the supply condition of the second emulsion rolling oil supplied to the upstream rolling stand entrance side, the first supplied to the final rolling stand entrance side Predict the supply conditions of the rolling emulsion oil of No. 2,
The second emulsion rolling oil supplied to the final rolling stand entry side so that the friction coefficient of the final rolling stand calculated from the predicted supply condition of the second emulsion rolling oil becomes the set target friction coefficient. Feed-forward control of the supply amount of
The predicted supply condition of the second emulsion rolling oil includes the surface roughness of the rolled material after rolling in the upstream rolling stand as a variable ,
The target friction coefficient is set based on the friction coefficient at the upstream rolling stand,
From the friction coefficient at the upstream rolling stand and the supply flow rate of the second emulsion rolling oil supplied to the inlet side of the upstream rolling stand, the surface roughness of the rolled material after rolling at the upstream rolling stand. Estimate
A cold rolling method, wherein the friction coefficient of the final rolling stand is estimated from the estimated surface roughness after rolling.   When the rolling material bites into the final rolling stand, the friction coefficient at the final rolling stand is estimated, the control amount of the feedback control is obtained from the estimated friction coefficient at the final rolling stand, and the above control amount of the feedback control is obtained. The cold rolling method according to claim 1, wherein a control amount of feedforward control is corrected.   The target friction coefficient is set such that an absolute value of a friction coefficient difference between a friction coefficient of an upstream rolling stand and a friction coefficient of a final rolling stand is 0 or more and 0.01 or less. The cold rolling method according to claim 1 or claim 2.   The metal plate manufacturing method characterized by manufacturing a metal plate by cold-rolling the rolling material used as a metal plate by the cold rolling method of any one of Claims 1-3.

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