JPH0422824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the torque ratio of a bridle roll used in a steel process line.

[Conventional technology]

Conventionally, methods for controlling the torque ratio of multiple motors for driving a bridle roll have been based on, for example, balancing the motor torque by using the drooping characteristics of the motor itself or by controlling the field by detecting the main circuit current. Various methods have been used, but in each case, the distribution was based on the motor capacity ratio, and the torque ratio of each motor was kept constant.

Next, an example of a conventional torque ratio control method will be explained with reference to FIG.

As shown in the upper part of FIG. 6, the strip St runs in the direction of the arrow. The bridle roll R _e on the entry side wraps around the running strip St, and the bridle roll R _d on the exit side wraps around the wrapped strip material St.
Rewind. In addition, the tension value on the inlet side of the strip St,
Let the exit side tension value and the tension value between each bridle roll R _e and R _d be F _e , F _d and F _n , respectively.
Also, the angle θ _e is the contact angle between the entry side bridle roll R _e and the strip St, and the angle θ _d is the contact angle between the exit side bridle roll R _d and the strip St.
V is the running speed of the strip St, and R is the radius of each bridle roll _Re , _Rd , both of which usually have the same radius. The motor M _e on the entry side drives the bridle roll R _e on the entry side. The motor M _d on the exit side drives the bridle roll R _d on the exit side. The pulse generator PG outputs a signal of the current speed value V _i that is proportional to the rotation of the output motor M _d . The speed command REF outputs a signal of the speed command value _Vs of the strip St to the subtractor SU. The subtracter SU subtracts the current speed value V _i from the speed command value V _s and outputs the result. The speed controller ASR outputs a signal of the current command value _Is for the output of the subtractor SU. The torque setting device S _d outputs a signal of a set value k _d of the current ratio of the output motor M _d . The torque setting device S _e outputs a signal of a set value k _e of the current ratio of the input motor M _e . Multiplier MP _e inputs and multiplies the current command value I _s signal and current ratio setting value k _e signal, respectively, and outputs the current command value I _se (=k _e I _s ) signal for the entrance roll. do. multiplier
MP _d inputs and multiplies the current command value I _s signal and the current ratio setting value k _d signal, respectively, and outputs a current command value I _sd (=k _d I _s ) signal for the exit roll.
The current controller ACR _e of the motor M _e on the input side inputs the signal of the difference between the current command value I _se and the feedback value of the current of the motor M _e , and controls the thyristor converter on the input side.
The converter THPS _e drives the input motor _{M e .} Outlet motor M _d current controller
ACR _d inputs the signal of the difference between the current command value I _sd and the feedback value of the current of the motor M _d , controls the thyristor converter THPS _d on the output side, and converts the converter
THPS _d drives the exit motor M _d . The current detector RH _e of the motor M _e on the inlet side and the converter on the inlet side
It is inserted between THPS _e and motor M _e and outputs a feedback signal of the detected motor current.
The input side subtractor SU _e is inserted between the input side multiplier MP _e and the current controller ACR _e , and calculates the difference between the above-mentioned current command value I _se and the feedback signal. Similarly, the current detector RH _d of the output motor M _d is inserted between the output conversion device THPS _d and the motor M _d ,
Outputs a feedback signal of the detected motor current. The subtractor SU _d on the output side is inserted between the multiplier MP _d on the output side and the current controller ACR _d , and takes the difference between the above-mentioned current command value I _sd and the feedback signal.

Note that FIG. 6 shows the case of a two-roll type bridle, and although the bridle is normally a two- to four-roll type, the present invention uses a two-roll type bridle.

Therefore, using the control circuit CON with such a configuration, the current ratio setting values k _e and k _d are inputted from the torque setting devices S _e and S _d , respectively, and multiplied by the current command value I _s to set the input and output values. Current command value of the motor for side rolls
By generating I _se and I _sd , the input and output motor torques were determined. At this time, the torque ratio between the inlet and outlet motors is constant as described above, and is distributed based on the motor capacity ratio.

[Problem to be solved by the invention]

In the conventional bridle roll torque ratio control method described above, the motor capacity is fixed and therefore the motor torque ratio is also constant, but the actual tension ratio of the strips before and after the bridle roll varies depending on the operating conditions. As a result, the conditions under which the bridle roll and strip do not slip change, and when the tension ratio of the strip before and after the roll changes significantly, slip occurs. In addition, when selecting the motor capacity,
Since torque and slip prevention conditions were to be satisfied based on various work conditions, there was a risk of over-specification.

An object of the present invention is to calculate a torque ratio that optimally satisfies the slip prevention conditions from the ratio of the set value of the strip tension before and after the bridle roll, and to control the output torque of each motor according to this torque ratio. Accordingly, it is an object of the present invention to provide a torque ratio control method for a bridle roll, which allows optimization of slip prevention and rational selection of motor capacity.

[Means to solve the problem]

The torque ratio control method for bridle rolls of the present invention provides a method for controlling the torque ratio of a strip material on the inlet and outlet sides of the bridle device during operation and in the middle between the inlet and outlet bridle rolls in a bridle device consisting of two bridle rolls. each tension value
Let F _e , F _d and F _n be the contact angle between the bridle roll and the strip material on the entry side, θ _e be the contact angle between the bridle roll and the strip material on the exit side, and θ _d be the contact angle between the bridle roll and the strip material on the exit side. Ratio f of material tension value F _e and F _d
is set, the following formula F _e /F _n = e〓 ^e 〓 ^e , F _n /F _d = e〓 ^d 〓 ^d (if F _e > F _n > F _d ) or, F _e /F _n = e ^- 〓 ^e 〓 ^e , F _n /F _d = e ^- 〓 ^d 〓 ^d (when F _e < F _n < F _d ), where e is the parameter μ _e and μ _d expressed in the base of natural logarithm. The following equation is derived by making the values equal. Means for determining the distribution of the output torque of each bridle roll drive motor, with τ given by as the required torque ratio of each entry side and exit side bridle roll, and controlling the output torque value of each bridle roll drive motor. have.

[Effect]

As shown in the upper part of FIG. 6, if the tension values of the strip material on the inlet and outlet sides of the bridle device consisting of bridle rolls (hereinafter referred to as rolls) R _e and R _d are F _e and F _d , respectively, The total output P of the motors for the two rolls is: P=(F _e -F _d )V...(1) Also, the total torque T output by the motors is: T=(F _e -F _d )R...( 2) becomes. However, V is the running speed of the strip material,
R is the radius of each roll, assuming that the mechanical efficiency of each roll is 100%.

Due to the tension F _n between rolls R _e and R _d , each roll R _e ,
Motor M _e divided by R _d , output P _e of M _d ,
P _d and torques T _e and T _d are respectively P _e = (F _e - F _n ) V...(3) P _d = (F _n - F _d ) V... (4) T _e = (F _e - F _n )R...(5) T _d =(F _n -F _d )R...(6) holds true.

By the way, let the tension values of the strip material at the entrance and exit sides of one roll be F ₁ and F ₂ , respectively.
When the tension ratio F ₁ /F ₂ increases or decreases and slip occurs between the roll and the strip material, the slip limit friction coefficient is μ ₀ and the contact angle is θ, then
At that time, the limit tension ratio between the input side and the output side of the strip is determined by the following formula (F ₁ /F ₂ ) _nax = e〓 ₀ 〓 (when F ₁ > F ₂ ) or (F ₁ /F ₂ ) _nio It is well known that = e ^- 〓 ₀ 〓 (when F ₁ < F ₂ ) holds true. The contact angle θ is determined _by the arrangement of the machine, and the critical friction coefficient _{μ 0} is a unique value determined by the material and surface condition of the roll ^and strip. If the tension ratio F ₁ /F ₂ of the strip material is within the range of both values, the strip will not slip. The tension ratio F ₁ /F ₂ within the range that does not cause this slip is F ₁ /F ₂ =e〓〓 (7) (when F ₁ > F ₂ ) or F ₁ /F ₂ =e ^- 〓〓 …( 7′) (when F ₁ < F ₂ ), μ is a parameter corresponding to the tension ratio F ₁ /F ₂ within the range that does not cause slip,
It takes a value smaller than the above-mentioned limit friction coefficient μ ₀ .

Therefore, regarding the bridle device mentioned above, F _e
Considering the case of >F _n >F _d , for each bridle roll R _{d and} R _e , from equation (7), F _e /F _n = e〓 ^e 〓 ^e and F _n /F _d = e〓 ^d 〓 ^d . You get a relationship. however,
θ _e and θ _d are contact angles between each roll Re _and R _d and the strip material, and μ _{e and} μ _d are parameters corresponding to each roll Re and R _d . Assuming that both rolls are made of the same material, in order to find the conditions under which both rolls R _e and R _d simultaneously generate slips with the strip material, we set μ _e = μ _d = μ and calculate F _e /F _d ＝e〓 ⁽ 〓 ^e+ 〓 ^d) …(8) is obtained. Further, the following discussion will be made assuming that F _e /F _d = f (tension ratio) (9).

From equation (8) μ(θ _e + θ _d )=lnf …(10) ∴μ=lnf/θ _e +θ _d …(11) F _n =F _e e ^- 〓〓 ^e …(12) Also, when F _n is induced using F _d , F _n =F _d e〓〓 ^d …(14) It is. Therefore, from equations (5) and (6), becomes. Here, if we set the torque ratio as T _e /T _d = τ...(18), then from equations (16), (17) and equation (9), get. Note that in the case of F _e <F _n <F _d , a similar calculation is performed using equation (7') to obtain the same result as equation (20) regarding the relationship between the torque ratio τ and the tension ratio f.

In other words, the torques T e and T _d of the motors M _e and M _d that drive both rolls R _{e and} R _d , respectively, are adjusted to the torque ratio shown by equation (20) with respect to the set target tension ratio f. Therefore, if the tension ratio of the strip material fluctuates due to some disturbance and the parameter μ exceeds the critical friction coefficient μ ₀ and slip occurs, then both rolls will slip at the same time. becomes.

As an example, if we consider the case of θ _e = θ _d for simplicity, τ = √...(21) Then, if we draw a graph using the tension ratio f as a parameter, it will be as shown in Figure 2.

Furthermore, if we consider the case of θ _e + θ _d = 2.5π, then μ = lnf / 2.5π (22) from equation (11), and if equation (22) is plotted on a graph, it is as shown in Figure 3. be.

Next, when the torque ratio τ is fixed as in the conventional method described above, we will examine how μ changes within a range in which both rolls do not cause slip. In other words, when the friction conditions of both rolls are not the same, and when the respective parameters are μ _e and μ _d , and F _e > F _n > F _d , F _e −F _n is obtained from equations (5) and (6). /F _n −F _d = τ (=constant) …(23) F _n =F _e +τF _d /1+τ …(24) F _n =F _e e ^- 〓 ^e 〓 ^e =F _d e〓 ^d 〓 ^eHere F _e e ^- 〓 ^e 〓 ^e =F _e +τF _d /1+τ −μ _e θ _e =ln(1+τF _d /F _e /1+τ) =ln(1+τ/f/1+τ) ∴μ _e =1/θ _e ln( 1+τ/1+τ/f) …(25) F _d e〓 ^d 〓 ^d = F _e +τF _d /1+τ μ _d θ _d = ln(f+τ/1+τ) ∴μ _d =1/θ _d ln(f+τ/1+τ) ( 26) Now, τ = 2, and θ _e = θ _d = 1.25π (rad),
Assuming θ _e + θ _d = 2.5π (rad), looking at the movements of μ _e and μ _d , μ _e = 1/1.25πln (3/1 + 2/f) μ _d = 1/1.25πln (f + 2/3) Similar calculations are performed when F _e <F _n <F _d , and the results are shown in FIG. 4.

To summarize here, if the torque ratio τ can be freely adjusted without being restricted according to the tension ratio f, as shown in equation (20) or Fig. 2, the relationship between the parameter μ and the tension ratio f is , as shown in FIG. 3, the range of the tension ratio f can be wider than in the case of FIG. 4. This will be explained below.

Now, the tension difference (F _e −F _d > 0) before and after the bridle rolls R _e and R _d is the maximum as seen from the motor side,
Considering the case where the tension ratio is 4 (f=4), from FIG. 2, τ=2 is obtained as an appropriate value.
Therefore, if the capacity ratio of the motors M _e and M _d is 2, in the conventional system it is fixed as τ = 2 (constant). This corresponds to the case in Fig. 6 where k _e /k _d = 2 and becomes a fixed value, and in this case, the parameter μ necessary for the friction condition of each roll without slipping for the tension ratio f is As shown in Figure 4. However, the value of the critical friction coefficient μ ₀ between each roll and the strip material is 0.2.

In Fig. 4, if |μ|<μ ₀ = 0.2, the limit of the tension ratio f at which no slip occurs is limited by the μ _d curve on the high side and the μ _e curve on the low side, respectively. The range of 0.35f4.6 is the limit.

On the other hand, even if the motor capacity ratio is fixed, if it is possible to devise a control circuit and set the torque ratio using equation (21), the same |μ|<μ ₀ =
When it is set to 0.2, f is 0.208f4.8 from Figure 3, which increases the range of allowable tension ratios, and it is clear that the capacity given by the machine arrangement can be maximized.

In practice, the magnitude of the front and rear tensions is often reversed depending on the driving mode.
If the tension ratio cannot be satisfied, it becomes necessary to increase the number of rolls and therefore the number of motors. This is unfavorable in terms of installation space and economy.

The bridle roll torque ratio control method of the present invention proposed here provides a means for most economically demonstrating the maximum capacity of the bridle roll.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration and application of a control circuit using an embodiment of the bridle roll torque ratio control method of the present invention.

The payoff reel POR rewinds the coil ST.
The first pinch roll 1PR is payoff reel POR
Pinch and feed the tip of the next strip St that is fed from the strip. The shear SH cuts off the defective part at the tip or tail end of the strip St coming from the first pinch roll 1PR. Welder WLD is a leading strip
Weld the tail end of St to the tip of strip St coming from shear SH. The second pinch roll 2PR is used for threading the tip and tail ends of the strip St coming from the welder WLD. bridle roll
BR tensions the strip St coming from the second pinch roll 2PR. 1st roll for direction change
R ₁ is the strip St coming from the bridle roll BR
It is for pointing upwards. The looper LP holds the strip St coming from the first roll _R1 upwards by means of a lifting device LT to accommodate variations in the strip length. Second roll material for direction change
_R2 is for horizontally directing the strip St descending from the looper LP.

Now, if you pay attention to bridle roll BR,
(i) Bridle roll BR from payoff reel POR
(ii) the normal mode of operation in which the strips are connected by the strip St; and (ii) the payoff reel
There are two modes: an unusual mode in which the tail end of the strip St separates from the POR and is supported only by the second pinch roll 2PR, and in these two modes, the tension ratio of the strip St before and after the bridle roll BR is In addition to the large change in F _e /F _d (=f), this tension ratio f also changes when strips St of different sizes are welded.
In the normal mode, what greatly influences the tension ratio f of the strip St before and after the bridle roll BR is the tension F _e between the payoff reel POR and the tension F _d between the looper LP.

To further explain FIG. 1, the inlet motor M _e drives the inlet bridle roll _Re , and the outlet motor M _d drives the outlet bridle roll R _d . The control circuit CON controls these motors M _e ,
It is for controlling M _d and has the same configuration as the control circuit shown enclosed by the dashed line in FIG. The left motor _M1 is the payoff reel POR
The right motor _M2 drives the lift device LT. The tension setting device RH ₁ is used to set the inlet tension F _e of the strip St.
The ACR ₁ inputs the input tension F _e signal from the tension setting device RH ₁ to control the current of the thyristor converter THPS ₁ , which drives _the motor _M1 . The tension setting device RH ₂ is used to set the output tension F _d of the strip St.
The ACR ₂ inputs the output tension F _d signal from the tension setting device RH ₂ to control the current of the thyristor converter THPS ₂ , which drives the motor _{M 2 .} The analog-to-digital converter AD ₁ receives an analog signal of the input tension F _e and converts it into a digital signal. analog to digital converter
AD ₂ inputs the analog signal of outlet tension F _d ,
Convert to digital signal. The divider DIV converts the digital signal of the input tension F _e from the analog-to-digital converter AD ₁ to an appropriately installed switch SW.
At the same time, a digital signal of the output tension F _d is inputted from the analog-to-digital converter AD ₂ and divided, and a signal of the tension ratio f shown in equation (9) is output. The function generator FG inputs and calculates the signal indicating the tension ratio f, and outputs the signal of the torque ratio τ of equation (21). Arithmetic unit for function 1/(1+τ)
CLU ₂ inputs the torque ratio τ signal from the function generator FG and outputs a digital signal of the set value k _d of the current ratio of the output motor M _d . The digital-to-analog converter DA ₂ receives a digital signal with a set value k _d and converts it into an analog signal. Function τ/(1+
The computing unit CLU ₁ of τ) inputs the signal of the torque ratio τ from the function generator FG and outputs a digital signal of the set value k _e of the current ratio of the input motor M _e . The digital-to-analog converter DA ₁ receives a digital signal with a set value k _e and converts it into an analog signal. The relationship between the set values k _e and k _d is k _e + k _d = 1...(28) k _e /k _d = τ...(29), so k _e = τ/1+τ...(30) k _d = 1/1+τ …(31) Therefore, each of the computing units CLU ₁ and CLU ₂ is
The set values k _e and k _d can be determined as described above.

From the above, the control circuit for motors M _e and M _d
CON can obtain an analog signal of the setting value k _d corresponding to the current ratio setting value k _d of the output motor M _d in FIG _.
An analog signal of the set value k _e corresponding to the set value k _e of the current ratio can be obtained.

In addition, the setting device S _e0 for the input side motor M _e in Figure 1
is the equivalent input tension F _e0 signal, and the switch SW
Output to divide DIV via. Furthermore, switch SW
is switched to the setter S _e0 side by a detection signal from a device (not shown) when the tail end of the strip St separates from the payoff reel POR. The equivalent entrance tension F _e0 mentioned above is, for example, the second
When the pinch roll 2PR cannot obtain sufficient tension _{F e} in terms of torque capacity, the strip _St This means applying a force N to hold down the

In this case, if F _e <F _d pressing force = N in Fig. 5, it can be treated equivalently as the entry tension of the entry bridle roll R _e using F _e ′ = F _e + μN (32). It refers to what can be done.

Furthermore, it goes without saying that a microcomputer or the like can be used as the signal processing device CPU enclosed by the dashed line in FIG.

〔Effect of the invention〕

As explained above, in the present invention, by calculating the optimum torque ratio corresponding to the tension ratio and applying it to the bridle roll motor, (1) the range in which the tension ratio can be set can be increased to the maximum; The possibility of slippage between the bridle roll and the strip is reduced, the reliability of the drive is increased, and the capabilities given by the machine arrangement are maximized.

(2) Regarding slip prevention conditions, two rolls and three
The difference between these rolls is small, and if two rolls are not enough, there is a strong possibility that four rolls will be used, but the difference between two and four rolls is large in terms of space and economy.
This has the effect of increasing the possibility that the number of bridle rolls may be small.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration and application of a control circuit using an embodiment of the bridle roll torque ratio control method of the present invention, and FIGS. 2 to 4 are tension diagrams for explaining the operation of the present invention. Graph showing the relationship between ratio and torque ratio or tension ratio, fifth
The figure is an explanatory diagram of the operation of the presser roll 61 in this embodiment, and FIG. 6 is a block diagram illustrating an example of a conventional bridle roll torque ratio control method. R _e , R _d , BR ... Bridle roll, St ... Strip, F _e , F _d ... Strip tension, M _e , M _d
... Motor, M ₁ , M ₂ ... Motor, CPU ... Signal processing device, CON ... Control circuit, f ... Tension ratio,
τ...Torque ratio.

Claims (1)

[Scope of Claims] 1. In a two-roll bridle device for a steel process line, the contact angle between each bridle roll on the inlet side and the outlet side and the strip material conveyed by the bridle roll, and the inlet and outlet sides of the bridle device. The ratio of the torque values generated by each bridle roll drive motor is calculated based on the tension value of the strip material with the side, and the torque value of each bridle roll drive motor is controlled according to the calculation result. This is a torque ratio control method, in which the tension values of the strip material at the entry and exit sides of the bridle device during operation and between the bridle rolls on the entry and exit sides are set as F _e , F _d and F _{n ,} respectively.
Assuming that the contact angle between the bridle roll and the strip material on the entry side is θ _e and the contact angle between the bridle roll and the strip material on the exit side is θ _d , the tension values of the strip material on the entry and exit sides F _e and F are When the ratio f of _d is set, the following formula F _e /F _n = e〓 ^e 〓 ^e , F _n /F _d = e〓 ^d 〓 ^d (if F _e > F _n > F _d ) or, F _e /F _n = e ^- 〓 ^e 〓 ^e , F _n /F _d = e ^- 〓 ^d 〓 ^d (when F _e < F _n < F _d ) where e is the parameter μ _e expressed in the base of natural logarithm and The following equation is derived by equalizing the values of μ _d Determine the distribution of the output torque of each bridle roll drive motor by setting τ given by as the required torque ratio of each inlet and outlet bridle roll, and calculate the output torque value of each bridle roll drive motor according to that torque ratio. Bridle roll torque ratio control method to control.