JP2003175417A - Reduction gear ratio switching method and device for running cutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction gear ratio switching method for a running cutter for cutting a material in synchronization with the speed of a continuously traveling material by a shear driven by an AC electric motor through a reduction gear. <P>SOLUTION: Exciting currents i<SB>01</SB>and i<SB>02</SB>are set on an exciting current setting device 91, the exciting current i<SB>01</SB>or i<SB>02</SB>is selected according to a reduction gear ratio switching signal to be outputted as the exciting current i<SB>0</SB>. Since the torque T of the AC electric motor is proportional to the exciting current i<SB>0</SB>, the reduction gear ratio can be switched. Accordingly, the reduction gear an be switched not to complicate mechanical configuration, and the work efficiency is improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear ratio switching method and apparatus for a cutting machine for cutting a material such as a steel plate, an aluminum plate or the like which continuously runs in synchronization with the moving speed of the material to be cut.

[0002]

2. Description of the Related Art Conventionally, a cutting machine for cutting a material such as a steel plate or an aluminum plate generates a cutting load when cutting the material in synchronization with the speed of the traveling material. The cutting load varies in size depending on the plate thickness, plate width, tensile strength of the material to be cut, and the moving speed of the material to be cut.

The speed reducer of the cross-section cutting machine is selected so that this cutting load becomes smaller than the maximum specification torque of the electric motor used. However, the cutting load of the material to be cut may be wide. For example, when cutting from a thin plate to a thick plate, or when cutting an iron steel plate and a stainless steel plate.

In this case, since the electric motor capacity is determined according to the maximum cutting load of the material to be cut, the cutting load cannot be set in a wide range. That is, assuming that the output of the electric motor is P, the rated speed is ω, and the torque is τ, P = τ · ω. Therefore, if the torque is increased according to the maximum cutting load, the electric motor capacity increases, and therefore the cutting load. To set a wide range, it is necessary to increase the capacity of the electric motor.

In order to solve the problem of the cutting load range, the fact that the load torque of the machine is proportional to the speed reduction ratio of the speed reducer is used to mechanically switch the speed reduction ratio to cut the range of the cutting load of the cross cutting machine. Is expanding.

FIG. 1 shows a numerical control circuit of a rotary shear, which is an example of a conventional cross-cutting machine of a method of mechanically changing a reduction ratio.

A high speed reducer 3A and a low speed reducer 3B are attached to the main shafts of a pair of rotary shears 2 each having a cutting blade (hereinafter referred to as a shear) on the circumferential surface in the axial direction to drive the rotary shear 2. AC motor for 4
Are combined. The AC motor 4 includes a pulse generator (P) for detecting the rotation speed and rotation angle of the motor, that is, the speed and rotation angle of the main shaft of the rotary shear 2.
G) 5 is provided.

On the other hand, a length-measuring roll 7 for detecting the amount of movement of the material 1 to be cut which is continuously running is provided, and a shaft of the length-measuring roll 7 is provided with a pulse generator (for detecting the amount of movement). PG) 8 and a cutting completion position sensor 6 for detecting the cutting position each time the traveling material 1 to be cut by the rotary shear 2 is cut.

Next, the structure of the numerical control circuit 70 of the rotary shear 2 shown in the figure will be described. The numerical control circuit 70 is disclosed in Japanese Examined Patent Publication No. 61-33679, and the numerical control circuit 70 includes a fixed length cutting circuit section 70A.
The stop control circuit unit 70B and the switching circuit unit 70C are included.

The standard length cutting circuit section 70A includes a cutting dimension setting unit 41, a first calculating unit 42, a timing signal generator 44, a circumference setting unit 45, a seat traveling distance detecting circuit 46, a motor rotation speed detecting circuit 47, and a first rotating unit. 2 operation part 48, D / A converter 4
9, function generator 50, F / V converter 51, operational amplifier 5
It is composed of two.

The stop control circuit section 70B comprises a stop distance setting section 61, a reversible counter 62, a D / A converter 63, a function generator 64, and a first comparing section 65.

The switching circuit section 70C comprises a second comparing section 53.

The standard length cutting circuit 70A is a circuit for accurately cutting the material 1 to be cut into a predetermined length, and every time the running material 1 is cut by the rotary shear 2.
The number of pulses corresponding to the difference L = L ₀ −B ₀ between the cutting length L ₀ and the circumferential length B ₀ of the rotary shear 2 each time the cutting completion position C is detected by the cutting completion sensor 6 and the cutting completion position signal is generated. Is read into the register.

The number of pulses Φa generated by the pulse generator 8 per unit rotation as the material 1 to be cut runs (ie,
The amount of movement of the material to be cut) and Φ generated by the pulse generator 5 per unit rotation as the rotary shear 2 rotates.
b (amount of rotation of the rotary shear 2) Φa−Φb,
That is, while compensating by R = L ₀ −B ₀ − (Φa−Φb), the compensation voltage Vc = f (R) corresponding to the difference R and the output of the pulse generator 8 are frequency-voltage (F / V) converted. Voltage obtained by (voltage indicating the amount of movement of the material to be cut 1)
The difference V ₀ = Va-Vc and Va, is input to the switching unit 70C.

The stop control circuit section 70B sets the stop distance of the shear preset in the stop distance setting section 61 each time the shear of the rotary shear 2 passes through the cutting completion position sensor 6 and the cutting completion signal C is generated. Corresponding number of pulses Φ
s is read into the reversible counter 62, and the pulse number Φb representing the rotation amount of the rotary shear 2 is subtracted. The output (Φs−Φb) of the reversible counter 62 is supplied to the D / A converter 63.
Then, it is converted into a DC voltage Vb proportional to (Φs−Φb). The first comparing section 65 compares Va and Vb and generates the lower one as the output voltage V ₁ .

The switching circuit section 70C determines the polarity of the difference V ₀ between the voltages Va and Vc representing the movement amount of the material 1 to be cut, and V
_{When 0} ≧ 0, the polarity determination comparator that generates the signal Sn indicating that and the polarity determination comparator
The V ₀ when not generating, also, when the polarity discriminating comparator generates a signal Sn is, V ₁ the final speed command voltage V
A switching circuit is provided to the drive control circuit 6 of the electric motor 4 as r.

As described above, in the numerical control circuit 70, the compensation voltage Vc is subtracted from the speed voltage Va of the material to be cut 1 to compensate for the speed of the material 1 to be cut according to the above R, and the cutting is performed. Sometimes R becomes zero and Vc = 0,
That is, with Vc = Va, the speed of the rotary shear 2 is synchronized with the speed of the material 1 to be cut, and Φa,
When either one of Φb advances or lags with respect to the other, digital servo control for accelerating and decelerating the electric motor is performed so as to make the difference zero, and the speed command Vr is output to the drive control circuit 80.

In the drive control circuit 80, a vector control system of an AC motor has been widely adopted in recent years, and a typical configuration is shown in FIG.

The drive control circuit 80 includes a subtracter 81, an amplifier 82, an arithmetic unit 83, an exciting current setting unit 84, and a coefficient unit 8.
5, an adder 86, a vector calculator 87, a two-phase / three-phase converter 88, a pulse width modulator 89, and a power unit 90.

The speed command V input to the drive control circuit 80
The speed of the main shaft of the AC motor 4 (rotational frequency f _N ) is subtracted by the subtractor 81, and r is input to the calculator 83 as the secondary current i ₂ of the AC motor via the amplifier 82.
On the other hand, the exciting current i ₀ is input to the calculator 83 from the exciting current setting device 84. Then, the arithmetic unit 83 divides the (secondary current i ₂ ) / (excitation current i ₀ ) and inputs it to the vector arithmetic unit 87 and the coefficient unit 85.

The coefficient unit 85 generates the slip frequency f _S of the AC motor from the value of (secondary current i ₂ ) / (excitation current i ₀ ) which is input, and inputs it to the adder 86. The adder 86 adds the rotation frequency f _N of the AC motor 4 (f _S
+ F _N ) and then input to the vector calculator 87.

The vector calculator 87 is also supplied with the exciting current i ₀ from the exciting current setting device 84. In the vector calculator 87, i ₂ / i ₀ , i ₀ , (f _S + f _N )
From the, the current command is vector-synthesized and the 2-phase / 3-phase converter 88
Are converted into three phases by the pulse width modulator 89, modulated by the pulse width modulator 89, and supplied as a primary current to the AC motor 4 by the power unit 90.

The AC electric motor 4 drives a rotary shear through a speed reducer. Now, if the reduction ratios of the high speed reducer 3A and the low speed reducer 3B are r _M1 and r _M2 respectively,
If the output shaft torques (machine shaft torques) T ₃ and T ₄ of the reduction gear are torque T of the AC motor,

[0024]

## EQU1 ## T ₃ = T × r _M1 T ₄ = T × r _M2

At the same time as switching to a desired reduction ratio, a reduction ratio switching signal is input to the coefficient unit to set a coefficient corresponding to each reduction ratio in the coefficient unit 9, and the pulse generator 5 is rotated as the rotary shear 2 rotates. Φb generated for each unit rotation is multiplied by a coefficient.

[0026]

According to the above-mentioned conventional mechanical reduction ratio switching method, the electric motor capacity remains unchanged,
Although it is possible to mechanically switch the reduction gear ratio and expand the cutting load range of the cross-cutting machine, there is a problem that the mechanical structure becomes complicated because the reduction gear is switched. In addition, there is a problem in that work efficiency is deteriorated because the reduction ratio is mechanically switched, and further, the machine configuration is complicated and therefore expensive.

An object of the present invention is to provide a reduction gear ratio switching method and apparatus for a cutting machine that solves such problems.

[0028]

According to the present invention, the above problem is solved by electrically switching the reduction gear ratio, not by mechanically switching the reduction gear ratio.

According to the speed reducer switching method of the first aspect of the present invention, when the shear cuts the material in the cutting machine for cutting the material in synchronization with the speed of the material which is continuously running, the material is cut. In order to cope with the shortage of the cutting torque due to the difference between the two, the exciting current of the AC motor is calculated from the preset reduction ratio for high speed, low speed, etc., and the current command of the AC motor is calculated from the calculated exciting current. Since the value of the torque generated by the AC motor is proportional to the exciting current, the reduction ratio is electrically switched according to the set reduction ratio.

Further, according to the speed reduction ratio switching device of the traveling cutting machine, which is the second aspect of the present invention, the material is cut in the traveling cutting machine which cuts the material in synchronization with the speed of the continuously traveling material. When the shear cuts, a means for setting an electrical reduction ratio for high speed, low speed, etc. to generate an electrical reduction ratio switching signal and an electrical reduction ratio switching in order to cope with insufficient cutting torque due to the difference in material Means for selecting an exciting current of the AC motor by a signal, and means for calculating a current command of the AC motor from the selected exciting current. Since the value of the torque generated by the AC motor is proportional to the exciting current, the reduction ratio is electrically switched according to the set reduction ratio, and the material is cut in synchronization with the speed of the continuously running material.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION A rotary shear control device according to the present invention is shown in FIG. FIG. 4 is a block diagram showing a drive control circuit of the control device of FIG.

In the control device of FIG. 3, the configuration of the numerical control circuit 70 for producing the speed command Vr is the same as that shown in FIG. The control device of FIG. 3 differs from the configuration of FIG. 1 in that only one speed reducer 3 is provided and the drive control circuit has a different configuration. In the present invention, the reduction ratio switching signal is input to the excitation current setting device 91 of the drive control circuit 100 of FIG. This switching signal can be input from a control device such as a computer. Drive control circuit 100
The other configuration is the same as that of the drive control circuit 80 of FIG.

FIG. 5 shows the configuration of the exciting current setting device 91. The exciting current setting device 91 includes a storage device 92, an address setting device 93, an exciting current setting device 94, and a writing switch 9
5 and.

With such an exciting current setting device, the exciting current i
_A case where ₀ is switched in two steps will be described as an example.

First, the exciting current i ₀₁ is set as the exciting current value, the memory address (for example, 0) is input to the memory device 92 by the address setter 93 as the address setting, and then the write switch 95 is turned on and a write command is issued. The exciting current i ₀₁ is stored in the storage device 92 as a parameter.

In a similar procedure, the exciting current i ₀₂ is stored in the storage device 92.
Is stored as a parameter at the address (for example, 1).

Since the storage device 92 outputs the stored value of the set address, the excitation current is output by inputting the speed reduction ratio switching signal as the address setting. For example, when the reduction ratio switching signal is 0, the exciting current i ₀₁ is output, and when the reduction ratio switching signal is 1, the exciting current i ₀₂ is output.

Speed command V input to drive control circuit 10
The speed of the main shaft of the AC motor 4 (rotational frequency f _N ) is subtracted by the subtractor 81, and r is input to the calculator 83 as the secondary current i ₂ of the AC motor via the amplifier 82.
Then, the calculator 83 divides (secondary current i ₂ ) / (excitation current i ₀ ) and outputs the result to the vector calculator 87 and the coefficient unit 85.

Further, as described above, the exciting current setting device 84
The exciting current i ₀ set by is output to the calculator 83 and the vector calculator 87.

Next, the coefficient unit 85 generates the slip frequency f _S of the AC motor from the input (secondary current i ₂ ) / (excitation current i ₀ ) value and inputs it to the adder 86. , And is added (f _S + f _N ) to the rotation frequency f _N of the AC motor 4, and then output to the vector calculator 87.

Further, in the vector calculator 87, i ₂ /
A current command is vector-synthesized from i ₀ , i ₀ , (f _S + f _N ), converted into three phases by the two-phase / three-phase converter 88, modulated by the pulse width modulator 89, and then converted by the power unit 90. It is supplied to the AC motor 4 as a primary current.

The AC motor 4 rotationally drives the rotary shear 2 via the speed reducer 3.

At this time, when the speed reduction ratio is electrically switched between high speed and low speed, it is necessary to switch the exciting current i ₀ in two steps. To this end, as described above, the exciting currents i ₀₁ and i ₀₂ are set in the exciting current setter 91, the exciting current i ₀₁ or i ₀₂ is selected by the reduction ratio switching signal, and the exciting current i ₀ is output. To do.

Generally, the torque T of the AC motor is proportional to the exciting current i ₀ in the region where there is no magnetic flux saturation.
The following equation is obtained.

[0045]

[Number 2] _{T = K 1 × i 0 (} K 1 is a constant) Then, if the speed reduction ratio of the reduction gear 3 and r, the exciting current i _01, reduction gear output shaft torque corresponding to the i ₀₂ (mechanical shaft torque ) T ₁ and T ₂ are

[0046]

## EQU3 ## T ₁ = K ₁ × r × i ₀₁ T ₂ = K ₁ × r × i ₀₂

Therefore, by switching the exciting current of the drive circuit from the equations (1) and (3), the electrical switching method (equation (3))
It can be seen that the reduction ratio can be realized in the same manner as the mechanical switching method (in the case of Equation 1).

In the above embodiment, the output shaft torque of the speed reducer is switched between two stages, high speed and low speed.
It is also possible to switch in more than one stage.

[0049]

According to the speed reducer switching method and apparatus for a cross-cutting machine of the present invention, since the speed reduction ratio can be electrically switched, there is a problem in the conventional mechanical speed reduction ratio switching. That is, it is possible to solve the problem that the mechanical structure is complicated because the speed reducer is switched, the cost is increased because the mechanical structure is complicated, and the work efficiency is deteriorated because the speed reduction ratio is mechanically switched.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control configuration of a conventional rotary shear.

FIG. 2 is a diagram showing in detail a drive control circuit of a conventional rotary shear.

FIG. 3 is a block diagram showing a control configuration of a rotary shear according to the present invention.

FIG. 4 is a diagram showing in detail a drive control circuit of the rotary shear according to the present invention.

5 is a diagram showing a configuration of an exciting current setting device 91. FIG.

[Explanation of symbols]

1 Material to be cut 2 Rotary shear 3 reducer 4 AC motor 5,8 pulse generator (PG) 6 Cutting completion position sensor 7 Measuring roll 9 coefficient unit 3A reducer 1 3B reducer 2 41 Cutting dimension setting device 42 First Operation Unit 44 Timing signal generator 45 circumference setting device 46 Seat mileage detection circuit 47 Motor speed detection circuit 48 Second operation unit 49,63 D / A converter 50,64 function generator 51 F / V converter 52 Operational amplifier 53 Second Comparison Section 61 Stop distance setting section 62 reversible counter 65 First Comparison Section 70 Numerical control circuit 70A fixed length cutting circuit 70B Stop control circuit 70C switching unit 80,100 drive control circuit 81 Adder / subtractor 82 amplifier 83 arithmetic unit 84, 91 Excitation current setting device 85 coefficient unit 86 adder 87 Vector calculator 88 2-phase / 3-phase converter 89 pulse width modulator 90 Power Department 92 Memory 93 Address setter 94 Excitation current setting device 95 write switch

Claims (4)

[Claims] 1. A method for switching a reduction ratio of a cross cutting machine, wherein a shear driven by an AC electric motor through a speed reducer cuts the material in synchronization with the speed of the continuously running material. When cutting, in order to cope with the insufficient cutting torque due to the difference in the material, the exciting current of the AC motor is calculated from the preset reduction ratio, and the current command of the AC motor is calculated from the calculated exciting current. , A method of changing the reduction ratio of a cutting machine, characterized by changing the reduction ratio. 2. The method for changing the speed reduction ratio of a cutting machine according to claim 1, wherein the speed reduction ratio is switched in two steps, one for high speed and the other for low speed. 3. A reduction ratio switching device for a cross cutting machine, wherein a shear driven by an AC electric motor through a reduction gear cuts the material in synchronization with the speed of the continuously running material. And a means for selecting an exciting current of the AC electric motor by the reduction ratio switching signal, and a means for calculating a current command of the AC electric motor from the selected exciting current. A gear reduction ratio switching device for a cross-cutting machine. 4. The reduction ratio switching device for a cross-section cutting machine according to claim 3, wherein the reduction ratio is switched in two stages for high speed and low speed.