JPS635164B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic speed reduction device for a tandem rolling mill.

A rolling mill that rolls a steel material wound on an unwinding reel performs deceleration control at the end of rolling to prevent dangers such as the tail end of the rolled material springing up.

As shown in Figure 1, the conventional automatic speed reducer decelerates the rolling speed all at once from the steady rolling speed to the end-of-line speed with only one stage of deceleration, and the target position of the tail end of the strip at the end of deceleration is around the position of the first stand. It is said that Further, the timing of deceleration is determined by monitoring the coil diameter of the rewind reel 1, as shown in FIG.

That is, the rotation of the rewind reel 1 and the deflector roll 2 is detected by PGs (pulse generators) 10 and 11, and the coil diameter of the rewind reel is detected by calculating the ratio with the coil diameter counter 17.

For example, PG10 generates one pulse per revolution of the rewind reel 1, PG11 generates 600 pulses per revolution of the deflector roll 2, the coil diameter counter 17 counts the pulses from PG11, and the PG11 generates 600 pulses per revolution of the deflector roll 2. Every time a pulse is generated, the count value is output and then cleared to zero. As a result, the count output of the coil diameter counter 17 detects the traveling plate length in one rotation of the rewinding reel, and this value can also be used as the value of the coil diameter.

The remaining coil diameter calculating device 24 reads the count output of the coil diameter counter 17 every time a pulse from the PG 10 is input, and calculates the remaining coil diameter from the difference between the coil diameter and the unwinding reel diameter.

The remaining plate length calculation device 25 calculates the remaining plate length from the remaining coil diameter and the set plate thickness of the unwinding reel.

The deceleration timing calculation/command device 26 calculates the length _of the plate running during _deceleration L (=V ₁ ² −V _T ² /2α), and when the remaining plate length calculated by the remaining plate length calculation device 25 matches the above-mentioned L, a deceleration command is output to the main control device (not shown).

However, in such a conventional configuration, the actual strip tail end position at the completion of deceleration is different from the target position.
There is a problem in that an error of about the length of one turn of the coil inevitably occurs, and this increases the rolling time. In general, in tandem rolling mills, it is desirable for the strip tail end position to be located on the rear stand at the end of deceleration in order to shorten the rolling time, but conventional machines do not take into account the rolling reduction ratio of each stand, so it is difficult to calculate the appropriate position. I couldn't do it. In addition, even if a rolling reduction calculation device is installed and the rear stand is set as the deceleration completion target, with only one stage of deceleration, the plate length due to the error in the deceleration start timing will be multiplied by the elongation rate of each stand until it reaches the deceleration completion target stand, resulting in a large error. It is difficult to achieve the target deceleration completion at the rear stand.

The present invention utilizes a two-stage deceleration method that divides the deceleration state into two stages, and accurately controls the start point of the second stage deceleration, thereby achieving a rational and efficient method for accurately completing deceleration at the target tail end position set on the rear stand. This is provided for automatic reduction gears for tandem rolling mills.

FIG. 3 is a hardware configuration diagram of the main parts showing one embodiment of the present invention in the case of a five-stand rolling mill. In contrast to the conventional configuration shown in FIG.
7. A load relay 28 is newly provided. Although it is not shown in the drawing, the unwinding reel, take-up reel, and each rolling stand each have a speed control device, and the overall rolling speed is set by the main controller (MRH) of the rolling system, and each is kept at a constant speed. Speed control is performed by ratio.

The deceleration timing calculation command device 26 uses the remaining plate length signal output from the remaining plate length calculation device 25 and the deflector roll 2 detected by the speed counter 18.
, the speed signal of each stand 3 to 7 detected by the speed counters 19 to 23, the rolling reduction ratio signal output from the rolling reduction calculation device 27, and the load relay 2
The first stand tail drop signal detected in step 8 is input, and the process is performed as shown in the flowchart of FIG.
Outputs the MRH 1st stage deceleration command, speed setting command upon completion of 1st stage deceleration, and 2nd stage deceleration command.

In the embodiment shown in Figures 3 and 4, the second stage deceleration start position (first position) is set at the first stand, and the deceleration completion point (second position) is set at the final stand (fifth stand). This is an example.

As shown in FIG. 4, the deceleration timing calculation command device 26 uses the first calculation means 31 to first calculate the speed from the first stand (second stage deceleration start position) to the deceleration completion point (bottom end position) set in the fifth stand. The plate length (distance) is calculated as the plate length (distance) L ₂ which is converted to the plate thickness on the entry side of the first stand based on the distance between the stands and the rolling reduction rate of each stand.

In other words, the thickness of the rolled plate decreases each time it is rolled, and if the rolling reduction rate of the stand is γ and the distance on the exit side is Ld, the distance Le converted to the entry side is given by Le = (1 - γ) Ld, and the rolling reduction ratio γ The value will be shorter than the distance Ld on the exit side depending on .

Further, the rolling reduction rate γ of each stand can be detected from the rolling speed ratio of each stand. That is,
If the speed and plate thickness on the inlet side of the rolling stand are V ₁ , H ₁ and the speed on the outlet side are plate thickness V ₂ , H ₂ , then V ₁ H ₁ = V ₂ H ₂ holds because the mass flow is constant. The rolling reduction rate γ of the stand is determined by the speed ratio of the entrance side and the exit side as γ=H ₂ /H ₁ =V ₁ /V ₂ , and each speed counter 18
~23 signals are detected.

Therefore, the rolling reduction rate γi of the i-th stand can be found from the speed ratio, and if the distance between the i-th stand and the i+1 stand is Li, i+ ₁ , the distance between the first stand and the fifth stand is calculated using the following formula L ₂ = (1 −γ ₁ ) [L _1,2 + (1−γ ₂ ) {L _2,3 + (1−γ
₃ ) (L _3,4 + (1-γ ₄ )L _4,5 )}] It is converted to the distance of the entrance side plate thickness.

Next, the second calculation means 32 calculates the initial speed at the start of second stage deceleration (first stage deceleration completion speed) _V2 .

At a constant deceleration rate α, if the initial speed is V _A, the final speed is V _B, and the deceleration time is T, then the speed ν during deceleration is ν=V _A −αt, where α=V _A −V _B /T is replaced. can. Therefore, the running wavelength L during deceleration is obtained by calculating L= ^∫T ₀ 〓 _dt as follows: L=V _A ² −V _B ² /2α (1).

Furthermore, from equation (1), the relational expression V _A =√2+ _B ² ...(2) can be obtained.

The deceleration timing calculation command device 26 calculates the initial speed V ₂ of the second stage deceleration from the relationship of the above equation (2) using the following equation (3).

V ₂ =√2 ₂ + _T ² ……(3) However, V _T is the target tailing speed converted to the plate thickness on the entry side of the first stand.

Next, by the third calculation means 33, the rolling speed is reduced from the steady rolling speed V ₁ at the entrance side of the first stand to the initial speed V ₂ of the two-stage deceleration at the deceleration rate α at the entrance side of the first stand (first stage deceleration). Calculate the running plate length L ₁ at the entrance of the first stand using the following formula.

L ₁ =V ₁ ² −V ₂ ² /2α (4) Note that the steady rolling speed V ₁ on the entrance side of the first stand is detected from the speed counter 18.

The deceleration timing calculation command device 26 further calculates the traveling wavelength L ₁ based on the first speed determined as described above.
is the remaining length input from the remaining board length calculation device 25.
Compare it with L _C moment by moment, and when L _C matches L ₁ + _L
Decelerate at deceleration rate α up to V ₂ . Note that _LX is the margin length that takes into account the remaining plate length detection error. Therefore,
In this example, due to the timing error of the first stage deceleration,
Even if there is a tail end in front of the first stand when the speed is reduced to _V2 , the rolling process is completed in a short time because it is rolled at the speed of _V2 .

In addition, when the tail end of the rolled material passes the first stand, a second stage deceleration command is output based on the detection signal from the load relay 28, and when the tail end of the rolled material is decelerated to the speed V _T at the deceleration rate α, the tail end of the rolled material is Reach the deceleration completion point (5th stand).

In this way, since the timing of the start of two-stage deceleration is detected by the load relay, the detection error can be reduced to zero.

In the above explanation, the deceleration of the second stage is started when the tail end of the strip passes through the first stand, but it may be configured to start at any stand taking into consideration the rolling reduction ratio of each stand. It is possible.

As explained above, according to the present invention, automatic deceleration is performed in two stages, and by the first stage deceleration, the first stage is set at the first position (first stand) with a constant remaining plate length.
The vehicle is decelerated to the stage deceleration completion speed (V ₂ ), and the second position (final stand) is achieved by performing the second stage deceleration by detecting the tail end at the first position (first stand).
Automatic deceleration of the tandem rolling mill enables accurate deceleration to a predetermined end-of-line speed, and even if there is an error in detecting the remaining strip length, rolling can be completed in a short time, improving productivity. You can get the equipment.

[Brief explanation of the drawing]

Fig. 1 is a speed chart showing the operation of a conventional one-stage reduction gear; Fig. 2 is a block diagram showing an example of a conventional automatic reduction gear; Fig. 3 is a block diagram showing an embodiment of the present invention; FIG. 4 is a flow chart showing the operation of the present invention, and FIG. 5 is a speed chart showing the operation of the present invention. DESCRIPTION OF SYMBOLS 1... Unwinding reel, 2... Entry side deflector roll, 3-7... Rolling stand, 8... Load cell, 9... Take-up reel, 10-16... Pulse transmitter, 17... Coil diameter counter , 18-23...
...Speed counter, 24...Remaining coil diameter calculation device, 25...Remaining plate length calculation circuit, 26...Deceleration command device, 27...Reduction ratio calculation device, 28...Load relay.

Claims (1)

[Scope of Claims] 1. A deceleration device that determines the deceleration start point from the remaining plate length (L _C ) of the rolling coil of the unwinding reel and decelerates the speed of the rolling line to the bottom-off speed (V _T ), comprising (a) A first step of converting the distance between a first position and a second position defined on the entry side and exit side of the rolling line into the plate length (L ₂ ) on the entry side (plate thickness) in consideration of the rolling reduction ratio. Calculating means (b) First stage deceleration completion speed (V ₂ ) from the plate length (L 2 ), tailing speed (V _T ) and deceleration rate ( _α )
(c) A second calculation means (c) calculates in advance the length of the plate (L 1 ) to be traveled during the deceleration period from the rolling speed (V ₁ ), the first stage deceleration completion speed (V ₂ ) and the deceleration rate ( _α ). (d) The remaining plate length (L _C ) of the rolling coil of the unwinding reel is a predetermined length (L ₁ +L _X ) calculated in advance.
When the speed decreases from the rolling speed (V ₁ ) to the first stage deceleration completion speed (V ₂ ) at a constant deceleration rate (α)
a first deceleration control means (e) that outputs a deceleration command to decelerate the rolling coil to the second position; and when the tail end of the rolling coil reaches the second position, the tail end speed ( _V
Automatic deceleration of a tandem rolling mill, characterized in that a second deceleration control means is provided for outputting a deceleration command to decelerate the machine to a maximum speed, and the rolling efficiency at the end of rolling is improved by outputting the deceleration command to a master control device. Device.