JPH0123246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a rotary shear that sequentially cuts various long materials such as steel pipes into predetermined lengths. This is what we are trying to provide.

A rotary shear is well known as a device that cuts various materials sequentially delivered from a delivery control device into predetermined lengths, and performs cutting operations independently without interlocking with the delivery control device. As a control device for such a rotary shear, West German Patent Publication No. 1463590 discloses, for example, a first register that adds and subtracts (L _p -A) the cutting length L _p of the material and the number of pulses A indicating the moving length of the material, and a shear. A mechanically determined constant B _p corresponding to one revolution of
A second register that adds and subtracts (B _p -B) the number of pulses B indicating the rotation angle of the shear, and a first D/A converter that converts the number of error pulses in the first register into a DC level signal. , a second D/A converter that converts the number of error pulses in the second register into a DC level signal, and the DC outputs of these D/A converters are added and subtracted (L _p −A−B _p +B ),
A comparator that adds and subtracts a signal obtained by once amplifying the output of this comparator and an analog quantity V A obtained by F/V converting the number of pulses _A , and a comparator that once amplifies the output of this comparator and sets it as a predetermined shear speed command. It consists of an amplifier and a servo system that drives the shear using a speed error voltage between the shear speed command signal and the actual shear speed detection signal, and it is configured to detect the magnitude of the material movement speed and the signal (L _p -A-B _p +B). By controlling the acceleration and deceleration of the shear according to the relationship, the material is cut to a set length. According to this control device, the number of error pulses in each register is converted into a D/A converter. Therefore, the error that occurs when converting the number of error pulses into a DC level in each D/A converter is directly reflected in the cutting length, resulting in poor cutting accuracy.

More importantly, since there is always a fixed error of a certain value in the circuit from the cutting dimension setting section to outputting the control command for the shear, the cutting command L _p is changed to (L _p - A) for each cut. If the register is preset to perform the calculation, the error becomes a repeating error and further deteriorates the cutting accuracy.

The present invention has been made in view of the above points, and will be explained below with reference to the drawings.

In the embodiment shown in the figure, 1 is a material such as a steel pipe that is brought in one after another, 2 is a shear, 3 is a speed reducer for reducing the speed of the shear, and 4 is a driving electric motor that drives the shear. DC motors are generally applied. 5 is a length measuring roll, 6 is a first pulse generator that generates the number of pulses according to the amount of movement of the material, and 7 is the number of pulses of pulse generator 6 so that the number of pulses per unit length is constant. 8 is an F/V converter that converts the number of pulses A multiplied by the coefficient into a DC level signal. 9 is a first register that performs the calculation (L _p - A) using the set length L _p of the material and the amount of pulse movement A of the material; 10 is a second pulse that generates a pulse according to the shear movement angle; In the generator, 11 is a second coefficient multiplier that multiplies the number of pulses of the pulse generator 10 by a coefficient so that the amount of shear movement per unit length is constant. Reference numeral 12 denotes a second register that performs the calculation (B _p -B) using a mechanically determined constant B _p corresponding to one rotation of the shear and the amount of movement B of the shear. 13 is the number of each input pulse (L _p −A),
14 is a digital adder/subtractor that digitally adds and subtracts (B _p -B), and 14 is a D that converts the number of error pulses {(L _p -A) - (B _p -B)} in the adder/subtractor 13 into a DC level signal. /A converter. Reference numeral 15 is a square rooter that reduces the gain when the input signal level is high, and on the other hand increases the gain when the input signal level is low to improve control responsiveness at the time of cutting. . 16 is the moving speed of the material V _A and the DC output of the flattener 15, that is, (L _p −B _p −A+B)
A first comparator 17 that compares the number of pulses converted into a DC level with a signal V _C is an amplifier that once amplifies the error voltage from the comparator 16 to produce a predetermined speed signal.

Reference numeral 18 is a third register for counting the signal from the second coefficient multiplier 11, and reference numeral 19 is a standby position pulse generator that operates the third register 18. 2
0 is the second D/D that converts the digital signal from the third register 18 into a DC level analog signal.
The A converter 21 reduces the gain when the input signal level is high, and on the contrary, increases the gain when the input signal level is low to efficiently and linearly decelerate when stopping at the standby position. This is a second squarer for converting to deceleration. 22 is this second
This is a minimum value calculation circuit which receives the output signal of the square root squarer 21 and the output signal V _A of the F/V converter 8 and calculates the smaller value of these input signals. These third register 18, standby position pulse generator 19, second D/A conversion circuit 20, second square rooter 21, and minimum value calculation circuit 22 constitute a standby position control circuit, and the cutting is completed. After that, the shear is driven to a standby position (for example, indicating top dead center) determined by the standby position pulse generator 19, and this movement is performed when L _p > B _p or L _p >>B _p It is done when there is a relationship between Reference numeral 23 denotes a maximum value calculation circuit which receives the output signal of the amplifier 17 and the output signal of the minimum value calculation circuit 22, and calculates only signals of large values from these input signals.

LS ₁ is a first limit switch that outputs a signal indicating the start of cutting the material, and LS ₂ is a second limit switch that indicates the completion of cutting the material. 24 is cosθ for correcting the shear speed so that the horizontal component in the moving direction of the shear V ₂ × cos θ (where V ₂ indicates the circumferential direction velocity component of the shear) and the moving speed of the material are synchronized at the time of cutting. This is a correction circuit. In this cos θ correction circuit 24, the flip-flop circuit 38 is set by a signal from the limit switch _LS1 , the flip-flop circuit 38 starts operating with an operation input signal from the limit switch LS2, the flip-flop circuit 38 is reset by a signal from the limit switch _LS2 , and the flip-flop circuit 38 is reset by a signal from the limit switch LS2. It is set in advance so that the operation ends when the operation input signal from the circuit 38 is cut off, and is comprised of an integrating circuit, a function generating circuit, etc. (not shown).

25 is a speed detection generator for extracting the actual speed signal of the drive motor 4; 26 is a speed detection generator for extracting the actual speed signal of the drive motor 4; and 26 is an output signal of this speed detection generator 25 and a maximum value calculation circuit 23
This is a second comparator that adds and subtracts the calculation signal of , and the correction signal of the cos θ correction circuit 24 . Reference numeral 27 denotes a servo control circuit that receives the output signal of the second comparator 26 and controls the acceleration and deceleration of the driving electric motor 4. Although not shown, the servo control circuit 27, for example, once amplifies the speed command signal and outputs it to a predetermined value. a current control amplifier that amplifies the current error voltage between the armature current detection signal that detects the armature current of the drive motor and the current command signal, and the output of this amplifier. A minor loop current control system consisting of an automatic pulse phase circuit for shifting the phase of the gate signal supplied to the thyristor rectifier according to the signal, and a Leonard device configured by connecting rectifiers in which bridge-connected thyristors are connected in antiparallel. It is configured.

28 is a fourth pulse generator, 29 is a first AND circuit which receives the pulse signal of the fourth pulse generator 28 as one input, and 30 also receives the pulse signal of the fourth pulse generator 28 as one input. This is the second AND circuit. 31 is a pulse number data signal corresponding to the set length L _p of the material, and a second limit switch LS ₂
cutting end pulse signal from the first AND circuit 2
This is the fourth register which receives the down count pulse train signal from 9 as input. 32 is a fifth register which receives as input a numerical data signal of the number of pulses B _p corresponding to one revolution of the shear, a cutting end pulse signal from the second limit switch LS ₂ , and a down count pulse train signal from the second AND circuit 30. It is. 33 is a third comparator that compares the count data X from the fourth register 31 and the count data Y from the fifth register 32.

34 is the output signal of the fourth register 31 and the third
The output signal of this third AND circuit is input to the first AND circuit 29. 35 is the output signal of the fifth register 32 and the output signal from the third comparator 33 to the not circuit 3.
The output signal of this fourth AND circuit 35 is input to the second AND circuit 30 . The output of the first AND circuit 29, ie, the pulse train signal of the pulse generator 28, is input to the first register 9 and is also supplied to the fourth register 31 as a down count input. At the same time, the second AND circuit 30
The output (indicating the pulse train signal of the pulse generator 28) is input to the second register 12 and is also supplied to the fifth register 32 as a down-count input signal. By the command pulse generator composed of each AND circuit, each knot circuit, each register, and a comparator, each command value of the cutting command length L _p and shear circumference length B _p is temporarily stored in the register 31 and the register 32, respectively. Although it is preset,
Ultimately, pulse train signals are taken out from the first AND circuit 29 and the second AND circuit 30 as L _p pulse trains and B _p pulse trains, respectively.

In the control device having the above configuration, at the end of cutting when the second limit switch LS ₂ operates, the number of internal error pulses R = (L _p
-B _p -A+B) is almost zero. At the end of this cutting, the cutting length L _p is recorded in the fourth register 31.
At the same time, the shear mechanical constant B _p is preset in the fifth register 32. L _p and B _p preset in each register 31 and 32 in this way are compared in magnitude by a comparator 33 and, for example, L _p > B _p (If the contents of the registers are indicated by X and Y, then X > Y ), the NOT circuit 36 outputs an "H" signal to the AND circuit 34, and the logical AND condition of the AND circuit 34 is established between this "H" signal and the signal from the register 31, and this AND circuit 34 leads the "H" signal to the AND circuit 29, and the gate is opened. When the gate of the AND circuit 29 is opened in this way, the pulse generator 28
→The pulse train is sequentially outputted to the first register 9 and the fourth register 31 over time through the path of the AND circuit 29, and in the case of the former register 9, the sequentially outputted pulse train and the coefficient unit 7 are used to output the pulse train. A predetermined calculation is performed using the movement amount pulse signal A of the material to be moved (the number of given pulses (the number of pulses is L _p in the end) - A), and the latter register 3 is
1, the sequentially input pulse train signals are subtracted from the preset value of L _p (the count content of the register 31 at this time is assumed to be X). Note that in the command pulse generator, the AND circuit 35 is connected to the NOT circuit 3.
Since the "L" signal is input from 7, this "L"
Since the AND condition is not satisfied between the signal and the signal from the register 32, the "L" signal is led to the AND circuit 30, and the gate of the AND circuit 30 is closed.

Therefore, when L _p and B _p are preset and there is a relationship of L _p > B _p (X > Y if the register contents are indicated by Then, this pulse train is added to the number of error pulses in the register 9, and a predetermined subtraction is performed between this addition output and the material movement pulse amount A. This subtraction output is converted into a DC level analog signal through the path of the digital addition/subtraction circuit 13 → D/A conversion circuit 14, and this analog signal V _C and the material movement pulse amount A are converted into a DC level voltage signal V _C. The first comparator 16 compares the obtained value with the obtained value. As a result of this comparison, there is a relationship of V _C > V _A , so the output V _p of the comparator 16 becomes negative because V _p = V _A - V _C , and the signal obtained by amplifying this V _p signal is sent to the maximum value calculation circuit 23. given to. This maximum value calculation circuit 23 is supplied with a set pulse amount to set the standby position of the shear blade through a path of standby position pulse generator 19 → register 18 → D/A conversion circuit 20 → square rooter 21 → minimum value calculation circuit 22. Since the signal B _o is given, the signal of the set pulse amount B _o is compared with the V _p signal output from the amplifier 17, and only the signal with the larger value is given to the final stage servo system. Here, the minimum value calculation circuit 22 outputs the smaller value of the signal from the square rooter 21 and the DC level material movement speed V _A derived from the F/V converter 8 to the maximum value calculation circuit 23 . In such a case, L _p ≫B _p or L _p
>B _p , the signal of the set pulse amount B _o at the standby position is larger, so it is output preferentially from the maximum value calculation circuit 23, and this set pulse amount
The drive motor 4 is driven in accordance with the signal B _o to move the shear blade to the standby position at top dead center.

Note that when the shear is driven to the standby position, the shear movement pulse amount B is given to the register 18 and the register 12 through the coefficient unit 11, respectively.
In the former register 18, the set pulse amount for the standby position
The shear movement amount B is subtracted from B _o , and the shear is driven until the contents of the register 18 become zero. On the other hand, the latter register 12
In this case, since the pulse train for the B _p signal has not yet been given, the inputted B signal is given to the digital subtraction circuit 13 as is. In this state, the register 31 of the command pulse generator sequentially subtracts from the preset value L _p according to the input of the pulse train, and the result of this subtraction (X) is stored in the register 32.
If it matches the preset value (Y) of B _p given by
This signal is inverted by the NOT circuit 37, and the gate of the AND circuit 35 is opened, and the pulse train inputted from the pulse generator 28 is applied to the register 12 and the register 32 through the AND circuit 30.
At this time, since the relationship of X=Y exists, the output of X<Y is also continuously negated, and the pulse train continues to be applied to each register 9 and 31. Therefore register 12
Now, with the pulse train derived from the command pulse generator and the shear movement amount B _o corresponding to the standby position,
The number of pulses given from the second AND gate 30 (finally becomes B _p - B _o )], and this signal (the number of pulses given from the second AND gate 30 - B _o ) is converted into a digital signal. The adder/subtracter 13 receives the number of pulses (L _p −X) − A given from the first AND gate 29 and the number of pulses (B _p −
A comparator 16 compares the V _C signal obtained by converting _the computation result into a DC level signal with the material movement signal V _A .

At this point of operation, for example, L _p ≫B _p , L _p >B _p
Since the V _C signal is greater than the V _A signal under the condition of , the output V _p of comparator 16 is still negative;
This _Vp signal and the standby position pulse signal (which is zero at this point) are given to the maximum value calculation circuit 23, and by the maximum value calculation, the standby position pulse signal is higher than the maximum value calculation circuit 23. A speed command is given to the servo system of the shear, and the shear remains in the standby position. Even when the shear is stopped, the material 1 advances in the forward direction of the shear, and in parallel, the material 1 is changed from each preset value by a pulse train input from the fourth pulse generator 28 to each register 31 and 32. The signals are sequentially subtracted, and when the contents of both registers 31 and 32 become zero, the signals input to the AND circuits 34 and 35 are switched from "H" to "L", and each AND circuit 29-3
Gates 0, 34-35 are closed respectively.
After the count contents of the registers 31 and 32 become equal, both registers perform subtraction counting at the same time, so that when the register contents become zero, the counting stops at the same time. Therefore, the pulse signal applied from the AND circuit 29 to the register 9 during the period from opening to closing of the gate of the AND circuit 29 has a pulse amount exactly equal to the preset value of L _p , and The pulse signal applied from the AND circuit 30 to the register 12 during the period from opening to closing of the gate is exactly equal in pulse amount to the preset value of _Bp .

The L _p and B _p values preset as described above are each converted into a pulse train signal group, and the shear is calculated based on these two signals, the material movement pulse amount A, and the shear movement pulse amount B. is driven by acceleration and deceleration. Now, when the pulse signals of L _p and B _p are given to the registers 9 and 12, the comparator 16
Since the output V _p of is negative, the shear 2 is kept in a stopped state while V _p is negative. Even when the shear 2 is in a stopped state, the material 1 is still moving, so
The number of error pulses R (R
= L - A) gradually decreases according to the moving amount A of the material, and when the value V _C obtained by converting the value of the error pulse number R to a DC level becomes lower than the moving speed V _A of the material, the speed decreases. When the command signal V _p becomes positive, it becomes larger than the command value based on the standby position pulse signal (which is 0 during standby stop) and is output preferentially from the maximum value circuit 23, and the shear is driven. be accelerated.

When the shear starts to accelerate in this way, the shear speed command signal V _p is V _p = V _A − V _C immediately after the start of acceleration.
, which is lower than the material movement speed V _A , but as the shear is accelerated and the speed of change in the shear movement pulse amount B approaches the change speed in the material movement pulse amount A, the degree of decrease in the error pulse number R increases. is slower than when the shear is stopped, and the shear continues to accelerate.

By shear acceleration control, while the number of error pulses R in the digital adder/subtractor 13 is large, the gain of the control system is reduced to reduce the responsiveness.
When the acceleration of the shear progresses sufficiently and the error pulse number R becomes small, the gain of the control system is sufficiently increased according to the square root characteristic curve by the action of the square rooter 15 to improve responsiveness and start the prescribed cutting. Continue accelerating the shear until the point. When the number of error pulses R in the digital adder/subtractor 13 becomes near zero, the speed command signal becomes only the moving speed V _A of the material, the shear speed and the moving speed of the material are synchronized, and the prescribed cutting begins. begins to be

When starting to cut the material, first limit switch LS ₁ is closed and a predetermined cutting start signal is generated.
A predetermined speed correction is made so that the horizontal component V ₂ × cos θ (where V ₂ indicates the circumferential direction speed of the shear) of the shear moving speed inputted to the cos θ correction circuit 24 becomes equal to the moving speed of the material. The signal is directed to a second comparator 26. This speed correction signal has the same polarity as the actual speed detection signal of the shear drive motor, and the signal obtained by adding the speed correction signal and the actual speed detection signal is the material moving speed signal V _A , that is, the shear speed command signal. Since the shear is driven by subtraction, the speed of the shear is sequentially reduced in accordance with the speed correction signal in synchronization with the moving speed of the material. In this way, the shear speed and material movement speed are synchronized during cutting, and when cutting is complete, the second limit switch LS ₂ is activated.
A predetermined disconnection completion signal is input to the reset terminal of the flip-flop circuit 38, the circuit is reset, and the correction circuit 24 is stopped.
L _p and B _p are preset in the registers 31 and 32 again.

Note that the above explanation is for L _p ≫ B _p and L _p > B _p , but in the case of L _p < B _p , the shear is immediately turned off when the second limit switch LS ₂ operates and the cutting is completed. As mentioned above, the blade is accelerated and controlled L _p ≫
Unlike the case of B _p , L _p > B _p , the pulse train given to registers 12 and 32 starts being given first, so the value of {(L _p −X−A)−(B _p −Y−B)} is The signal that first becomes negative and is output from the amplifier 17
V _p = V _A − V _C (where, V _A indicates the moving speed of the material converted to a DC level signal, and V _C indicates the value converted from the digital addition/subtraction calculation output value to a DC level signal. In this case, V _C is negative, so V _p is larger than V _A ) is processed in the maximum value calculation circuit 23 with priority over the signal derived from the minimum value calculation circuit 22, and predetermined acceleration control is performed based on this V _p signal. It will be done. Note that the second limit switch
This is the time when LS ₂ operates and the cutting is completed, but at this point, the calculation of (B _p - B) is performed regardless of the conditions of L _p ≫ B _p , L _p > B _p , and L _p < B _p . register 1
The content of 2 is zero, and the content of register 9 that performs the calculation of (L _p - A) is that the error that occurs for each cutting remains as residual data, and this residual data is used for the newly set material. The cutting command amount L _p is added as is, and the remaining data is not canceled. This further improves cutting accuracy itself.

Select the larger of L _p and B _p (X, Y), first give a pulse train to the first or second register, then when the contents X and Y of the fourth and fifth registers match (smaller The reason for applying pulse trains to both registers (when X=Y) is as follows.

In other words, the cutting is completed and the limit switch is
After operating the LS ₂ , the shear is ready for the next cut.
When L _p < B _p , it is accelerated, and when L _p > B _p , L _p >> B _p , it is decelerated to stop at the standby position.
Deceleration or acceleration is determined depending on whether the value of (L _p − B _p ) is positive or negative. Depending on the magnitude of this value, the amount of deceleration and waiting for the material to advance, or the amount of acceleration and material The amount to overtake is determined. After cutting is completed, it is necessary for efficient cutting to accelerate or decelerate without delay in preparation for the next cut. In this control device, the registers 31, 32, the comparator 33, and the AND gates 29, 30, 34, 35 give priority to the pulse train corresponding to the difference between L _p and B _p after the cutting is completed, and give it to the register 9 or 12. By applying a pulse train of a common amount to L _p and B _p successively, control is performed to accelerate or decelerate the shear for the next cut immediately after cutting is completed. I am doing this,
Excellent cutting efficiency is achieved.

As explained above, in the present invention, preset L _p and B _p given at the time of completion of cutting are used.
is converted into a pulse train signal group corresponding to L _p and B _p using a command pulse generator, and (L _p -A), (B _p -B)
Since this is applied to each register that performs the calculation, various effects can be obtained as shown below.

(L _p −A), (B _p −B) and (L−A+B,
However, since all calculations of L=L _p -B _p are performed by digital processing, it is possible to realize a shear control device with very high precision.

Since a cos θ correction circuit is provided to correct the speed during cutting, it is possible to realize a highly versatile control device that can perform predetermined cutting control regardless of the thickness of the material.

Especially when the cutting conditions are L _p ≫ B _p or L _p > B _p ,
Since the shear blade is once driven to the standby position at the top dead center and then put on standby, it completely solves the drawback of conventional devices where the standby position of the blade rotates every time each cut is completed, making stable control impossible. It is possible to realize a device with high stability and reliability in terms of control.

Since the control system is equipped with a flattener that adjusts the gain, it is possible to improve control responsiveness when the shear blade reaches the target position, and it is possible to shorten the time required for cutting.

[Brief explanation of drawings]

The figure is a block diagram of a rotary shear control device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Material, 2... Shear, 3... Reduction gear, 4... Drive electric motor, 5... Length measuring roll, 6... First pulse generator, 7... First coefficient unit, 8... F/V converter, 9
...first register, 10...second pulse generator,
11...Second coefficient unit, 12...Second register, 1
3... Digital adder/subtractor, 14... First D/A converter, 15... First square rooter, 16... First comparator, 17... Amplifier, 18... Third register, 19
...Standby position pulse generator, 20...Second D/A converter, 21...Second square rooter, 22...Minimum value calculation circuit, 23...Maximum value calculation circuit, 24...Cosθ correction circuit, 25...Speed detection generator, 26... second comparator, 27... servo control circuit, 28... cutting length command pulse generation circuit, 29... first AND gate, 30
...Second AND gate, 31...Fourth register,
32...Fifth register, 33...Third comparator, 3
4...Third AND gate, 35...Fourth AND gate, 36...First note circuit, 37...Second note circuit, 38...Flip-flop circuit, LS ₁ ...
1st limit switch, LS ₂ ...2nd limit switch.

Claims (1)

[Claims] 1. A first register 9 that adds and subtracts (L _p −A) a signal L _p indicating the cutting length of the material and a signal A indicating the moving length of the material, and a first register 9 corresponding to one revolution of the shear. Constant B _p
and signal B indicating the rotation angle of the shear (B _p
-B) second registers 12 and these first registers 12;
and a digital adder/subtractor 13 that performs calculations based on the output signal of the second register, and a D/A converter 14 that converts the error signal (L _p -B _p -A+B) of this adder/subtracter into a DC level signal. , this D/A
A first comparator 1 that compares the DC output of the converter with the material movement speed V _A obtained by F/V converting the signal A indicating the movement length of the material and converting it into a DC level signal.
6, and controls the acceleration/deceleration of the shear drive electric motor 4 based on the error voltage signal from the first comparator and the actual speed detection signal of the shear to cut the material into a predetermined size. In the control device for the shear, the fourth register 31 presets the pulse command amount L _p of the material at the time of completion of cutting the material, and the rotation angle amount B _p of the shear at the time of completion of cutting the material. Preset fifth register 32
and compare the counts of the fourth and fifth registers, and calculate the counts of the fourth and fifth registers X, Y.
Comparison means 33 for selecting and outputting the larger one of the
When X>Y, this comparison means 33
and the output signal of the fourth register is established, a pulse train of the signal L _p indicating the preset cutting length of the material is outputted to each of the first and fourth registers, and the A cutting length command is sent to the first register 9, a preset subtraction signal is sent to the fourth register 31, and when the content values X and Y of the fourth and fifth registers 31 and 32 match, The output signal of the fourth register and the output signal of the comparison means are logically ANDed to supply a pulse train to each of the first and fourth registers, and the contents of the fourth register become zero. first AND circuit means 36, 34, 2 for stopping the supply of the pulse train to the first and fourth registers at a point in time;
9, and in the comparison means 33, when X<Y, the AND of the output signal of the comparison means and the output signal of the fifth register is established, and the pulse train of the preset shear rotation angle amount B _p is The signal is output to the second and fifth registers 12 and 32, respectively, with a constant corresponding to one revolution of the shear for the second register 12, a preset subtraction signal for the fifth register 32, and a preset subtraction signal for the fifth register 32. When the content values X and Y of the fourth and fifth registers 31 and 32 match, a logical product is established between the output signal of the fifth register and the output signal of the comparison means, and each of the second and fifth registers is second AND circuit means 37, 35, 30 that supplies the pulse train to the register and stops supplying the pulse train to the second and fifth registers when the contents of the fifth register become zero; A rotary shear control device characterized by comprising: