JPH0667239B2 - Servo motor speed controller - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a servomotor speed control device useful for control axes of various machine tools, robot control axes, and various other moving bodies.

[Description of Prior Art] As a speed control device for a servo motor, for example, there is one that is performed using a digital-analog (hereinafter referred to as D / A) converter.

A speed control device using this D / A converter inputs a speed command unit that outputs speed command data as binary data of a predetermined bit (for example, 8 bits) and binary data output from the command unit. D / that outputs voltage based on data
It is configured to include an A converter and a servo amplifier that amplifies the voltage output from the converter and provides the servo motor with the voltage output from the converter. In this case, the speed command section can output the speed command data in half steps of 2 (predetermined number of bits) squared. Here, the number of steps is halved in order to control the servomotor in both forward and reverse directions.

However, when the above speed control device is applied to a moving body, such as a back gauge of a folding machine, which moves rapidly and requires accurate positioning, the following problems occur. Becomes

For example, the back gauge must be moved quickly and accurately positioned, but when a low bit D / A converter such as 8 bits is used, the speed change value per unit command data, that is, the speed resolution is Since this is inferior, high-precision speed control cannot be performed in the low-speed range, and the positioning accuracy deteriorates.

If the number of bits of the D / A converter is set to a desired number of bits, the circuit becomes complicated and the completed device becomes expensive.

An object of the present invention is to improve the above-mentioned problems, to enable a movable body to operate at a high speed, to improve the speed resolution in a low speed range, and to control the position of the movable body quickly and accurately. The purpose is to provide a simple configuration.

[Summary of the Invention] In order to achieve the above object, the present invention relates to a speed detector for detecting the rotation speed of a servo motor, a position detector for outputting a pulse signal proportional to the rotation amount of the servo motor,
A positioning module for outputting a speed command of the servo motor as a voltage, and a servo amplifier for amplifying an input voltage from the positioning module and outputting the amplified voltage to the servo motor. The module includes a binary data output unit that determines a command speed according to a predetermined speed pattern based on a movement command value and outputs command data, and a weight output unit that outputs a weight corresponding to the command speed. A speed command unit and a D / A conversion unit that generates a voltage corresponding to the weight from the weight output unit and outputs a voltage obtained by multiplying the voltage resolution by the command data to the servo amplifier. is there.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a side view of a folding machine capable of implementing the present invention.

The folding machine 1 has a punch 5 fixed to the upper frame 3 and a die 11 fixed to the upper end of a ram 9 driven up and down by a cylinder 7. Back gauge device 13 is a speed detector
15, a servomotor 19 including a position detector 17, a screw member 21 rotationally driven by the motor 19, and the screw member
A nut member 23 that moves in the front-rear direction of the folding machine 1 by the rotation of 21 and a back gauge that is fixed to the nut member 23 and is in contact with the end surface of the workpiece W that is inserted from the front-rear direction of the folding machine 1. It consists of 25 and. The back gauge device 13 is a bracket attached to the ram 9.
Supported by 27.

An operation panel 29 is provided on the front upper portion of the folding machine 1. The operation panel 29 is provided with a ten-key pad, other various operation keys and indicators, and the folding machine 1 can be operated to switch between automatic and manual modes and to control the movement of the back gauge 50.

A control box 31 for controlling the folding machine 1 is attached to the outer wall of the side frame. In the control box 31, a positioning module for positioning the back gauge is stored, as well as various modules for controlling the raising / lowering command of the ram 9 and the upper limit position of the ram 9. Also, a host CPU for centrally controlling each of these modules is stored. The broken line in the figure indicates a communication line.

In the folding machine 1 configured as described above, the back gauge 25 is positioned at a predetermined position, one end surface of the workpiece W is brought into contact with the front end of the positioned back gauge 25, and then the ram 9, that is, the die. Punch workpiece W by raising 11
It is possible to press-contact between 45 and the die 11 to perform a predetermined bending process.

Therefore, the positioning work of the back gauge 25 needs to be performed promptly and accurately. If it is not done promptly, the efficiency of the bending work is reduced, and if it is not accurately positioned, the product accuracy is deteriorated. I will let you.

FIG. 2 shows a block diagram of a servo motor control device.

The servo motor control device 33 includes an operation unit 29A and a host CPU.
31A, positioning module 31B, and servo amplifier 31C
And a speed detector 15 and a position detector 17. The speed detector 15 outputs a voltage proportional to the rotation speed of the servo motor 19. The position detector 17 is composed of a pulse encoder and outputs a pulse signal proportional to the rotation amount of the servo motor 19. The detection voltage of the speed detector 15 is fed back to the servo motor amplifier 31C and the positioning module 31B. The detection signal of the position detector 17 is fed back to the positioning module 31B.

The positioning module 31B has a speed command section 39 having a binary data output section 35 and a weight output section 37, and a D / A conversion section 41.
And have.

The speed command unit 39 inputs the movement command value output from the host CPU 31A, determines the command speed ν according to a predetermined speed pattern, outputs the command data D from the binary data output unit 35, and outputs the weight output unit 37. To output the weight e.

As shown in FIG. 3, the velocity region is set to velocity ν ₁ (for example, 30
High resolution range of less than m / min) and velocities ν _{1 to} ν ₂ (ν ₂ =
2 · ν ₂ , for example, 60m / min), and medium velocity range ν ₂
Above, divided into low resolution regions of ν ₃ (ν ₃ = 4 · ν ₁ ),
The weight in each region is defined as 1,2,4. Then, in the positive (plus) direction, the command data D is calculated by D = IFIX (ν / νi) · 127 (1) for each area, and in the negative (minus) direction, D = IFIX (ν / νi ) ・ 128… (2) is calculated (νi is the full-scale velocity of each area, IFIX is an integer function), and the full-scale in the negative direction is 0000000.
0, speed zero is 10000000, and full scale in the plus direction is 11111111.
The binary data D is output from the line 43 of the book.

The D / A converter 41 receives the command data D and the weight e, generates a voltage Ee proportional to the weight e, and outputs the voltage Ee.
Voltage obtained by dividing Ee by 127 in the positive direction and 128 in the negative direction by multiplying the voltage resolution Ee / D ₀ by the command data D EeD /
It will output D ₀ . As for the voltage Ee proportional to the weight e, the preliminary voltages E ₁ , E ₂ (2 · E ₁ ), E ₄ (4 · E ₁ ) may be selected by the weight e, or an appropriate electronic circuit is configured. Then, the maximum voltage (full-scale voltage) E ₄ may be divided and obtained according to the weight e.

The servo motor 19 receives the output voltage from the servo amplifier 31c, rotates at a predetermined rotation speed, and moves the back gauge 25 at a predetermined speed ν in either forward or reverse directions. The detection voltage of the speed detector 15 is the servo amplifier 31c and the speed command unit 3
Since it is fed back to 9, the output voltage of the servo amplifier 33 is optimized, and since the detection pulse signal of the position detector 17 is fed back to the speed command section 39, it is possible to perform a predetermined speed pattern control and a predetermined command position. Positioning can be stopped at.

FIG. 4 shows an example of position and speed pattern control.

It is now assumed that the back gauge 25 is at position P ₁ . Then, it is assumed that a movement command to the position P ₆ is output from the host CPU 31A.

Then, the speed command unit 39 sets the acceleration, constant velocity, and deceleration regions as a function of position based on a predetermined speed pattern table. And the area where the velocity value is V ₁ or less
Area where the weight is 1 for A ₁ and A ₅ and the velocity value is V ₁ −V _2.
A ₂ and A ₄ in the weight and 2, the area A ₃ of the velocity value V ₂ or more
Then, the weight is set to 4. Also, in the area of weight 1, the speed V ₁ at full scale, in the area of weight 2 the speed V ₂ at full scale,
Considering that the velocity V ₃ can be obtained in full scale in the area of weight 4, the data D is generated, and this data D
The evolution data is output to the D / A converter 41 together with the weight e.

The D / A converter 41 forms the voltage Ee proportional to the weight e, and the voltage resolution Ee / D ₀ determined by this is multiplied by the data to obtain the voltage Ee.
Ee · D / D ₀ is output.

The servo amplifier 31c amplifies the input voltage Ee · D / D ₀ to a predetermined value and outputs the amplified voltage to the servo motor 19, so the servo motor 19 moves the back gauge 23 according to the speed pattern shown in FIG. It will be. As a result, since the control is performed with high resolution in the low speed region, it is possible to stop the positioning of the back gauge 23 with high accuracy without swinging the speed.

[Effect of the Invention] The speed control device for a servo motor according to the present invention, which enables the low bit D / A converter to be used at high resolution by issuing a weighting command, has a simple structure and is inexpensive. It is controllable, the moving body can be operated at a high speed, the speed resolution in a low speed region can be improved, and the positioning of the moving body can be performed quickly and accurately.

[Brief description of drawings]

FIG. 1 is a side view of a folding machine for carrying out the invention, and FIG.
FIG. 3 is a block diagram of a servo motor control device according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of weighting, and FIG. 4 is an explanatory diagram of speed control. 19 …… Servo motor, 31c …… Servo amplifier 35 …… Binary data output section, 37 …… Weight output section 39 …… Speed command section, 41 …… D / A conversion section

Claims (1)

[Claims] 1. A speed detector (15) for detecting the rotation speed of a servo motor (19), and a position detector (17) for outputting a pulse signal proportional to the rotation amount of the servo motor (19).
A positioning module (31B) that outputs a speed command of the servo motor (19) as a voltage, and the servo motor (1) by amplifying an input voltage from the positioning module (31B).
9) A servo motor speed control device including a servo amplifier (31C) for outputting to the positioning module (31B), which determines a command speed according to a predetermined speed pattern based on a movement command value and outputs command data. A speed command section (39) including a binary data output section (35) for outputting (D) and a weight output section (37) for outputting a weight (e) corresponding to the command speed; The voltage (Ee) corresponding to the weight (e) from the weight output section (37) is generated, and the voltage (Ee / D ₀ ) is multiplied by the command data (D) to obtain the voltage (Ee · D / D _0). ) Is output to the servo amplifier (31c), and the D / A conversion part (41) is provided, The speed-control apparatus of the servomotor characterized by the above-mentioned.