CN102107544B - Pressure control method for servo crank press - Google Patents

Abstract

The invention relates to a pressure control method for a servo crank press. Different maximum motor torques of the servo crank press are preset according to different rotating angles in which a crank of the servo crank press is positioned and machining pressure set by process requirements, and the power transferred by a crank connecting rod in the machining motion direction is controlled by controlling the motor torques so as to the machining pressure of the servo crank press. In the pressure control method, the motor torques are controlled directly to control the machining pressure without connecting special pressure monitoring equipment externally, so the hardware configuration of a system is simplified greatly, the cost of the equipment is reduced, the operation is simple and convenient, the maintenance is easy, and the control accuracy of the machining pressure is +/-1 percent.

Description

A kind of compress control method of servo crank presser

Technical field

The pressure that the present invention relates to press machine tool is controlled, and belongs to metal stamping Pressure Control Technology field, is specially a kind of compress control method of servo crank presser.

Background technology

Pressure processing is to utilize the mould that is arranged on respectively slide block and workbench, under the punching press of slide block straight reciprocating motion effect, makes blank material generation plastic deformation or separation and the processing method of chipless.Tonnage is excessive may be caused, and the product of processing is defective, processing work, and even grinding tool is directly destroyed; Cause slide block not move or during operate miss,, as without pressure, controlling, may destroy because pressure is excessive plant equipment, generation pressure processing safety problem when machinery breaks down.Therefore, it is very necessary forcing press being carried out pressure control.The pressure control mode of existing servo-pressing machine is to measure tonnage by pressure monitoring module tonnage instrument or special-purpose pressure measuring device, tonnage feeds back to digital control system with numeral or analog quantity mode, and digital control system realizes reducing or increasing tonnage according to the motion of the tonnage adjusting slider of feedback.There is following problem in actual use in this tonnage control model:

(1) tonnage instrument or special-purpose pressure measuring device are expensive, and the proportion that accounts in the cost of equipment is larger, and enterprise is in order to save cost, the pressure control module of enable system not under a lot of application scenarios.

(2) mounting condition of tonnage instrument is harsher, and Rig up error does not reach desirable control effect.

(3) take the usage space of control system, make the complex structure of control system, on-the-spot line is also complicated.

(4) increased the maintenance cost of equipment.

List of references 1: plus-pressure autocontrol method and the device thereof of press machine tool, the patent No.: CN92115170.5

Summary of the invention

The problem to be solved in the present invention is: prior art is controlled and is needed special-purpose pressure monitoring devices the pressure in pressure processing, and monitoring equipment is with high costs, and maintenance cost is high, makes the control system complex structure of pressure processing, controls effect undesirable.

technical scheme of the present invention is:, a kind of compress control method of servo crank presser, servo crank presser comprises motion controller, servo-driver and motor, different rotational angle residing according to the servo crank presser crank, and the tonnage of technological requirement setting, the maximum motor torque that given servo crank presser is different, control the power of the working motion direction of crank connecting link transmission by the torque of controlling motor, control the tonnage of servo crank presser, wherein, motion controller dynamically calculates the moment of resistance on electric system inertia and motor shaft:, for the calculating of electric system inertia, utilize automatic inertia identification module that servo-driver provides to carry out system inertia to crank at different position of rotation and identify and preserve, the moment of resistance on motor shaft is dynamically calculated according to the position of crank and slide block by motion controller, the crank that motion controller is tried to achieve according to the working motion curve and the current location of slide block, movement velocity and acceleration, calculate current position to crank given given with torque motor, motion controller Negotiation speed/torque mode is sent to servo-driver with the given and given mode with analog quantity or bus of torque in position, the speed/torque control model of utilizing servo-driver to provide, realization is controlled the torque of motor, and then realization is to the control of tonnage.

The present invention includes following steps:

1) measure the system inertia of electric system under the crank different angles by automatic inertia identification module: lathe is unloaded, the step angle that crank rotates is set, often walk a step angle and carry out an inertia measurement, and preserve the electric machine rotation angle of this moment and the system inertia of measurement;

2) servo-driver is arranged to the speed/torque control model;

3) the maximum tonnage of servo crank presser is set;

4) the lathe band carries and does working motion, and motion controller is at each control cycle according to maximum tonnage and the residing anglec of rotation of crank, and calculating time processing pressure decomposes the effect torque on crank;

5) the useful motor torque T of motor generation is expressed as

$T\left(t\right)=J_e\frac{\mathrm{dw}\left(t\right)}{\mathrm{dt}}+\mathrm{Bw}\left(t\right)+T_s\left(t\right)---\left(1\right)$

J in formula _e---be converted to the inertia on motor shaft, i.e. step 1) the electric system inertia measured;

B---slide block viscous friction coefficient;

T _s---be converted to the moment of resistance on motor shaft, i.e. step 4) the effect torque that calculates;

W (t)---motor angular velocity

---the motor angular acceleration

Step 4) the current angular acceleration of effect torque, motor that calculates

Bring formula (1) into and calculate the needed torque T of motor;

6) step 5) the motor torque T that obtains and motion controller calculate movement velocity simulation output according to working motion curve negotiating PID controller and send to servo-driver;

7) servo-driver is controlled velocity of rotation and the output torque of motor according to given speed, torque.

In the present invention, automatically the method for inertia identification module inertia identification is: regard the rotor inertia of load inertia and motor as a whole inertia, servo-drive system is carried out the linear deceleration motion, draw system output torque and motor mean speed in this section period, obtain the servo-drive system average torque by system output torque,, according to the total time of motor mean speed, servo-drive system average torque and system acceleration and deceleration operation, obtain the value of described electric system inertia again, the specific implementation step is:

1) system is servo enables, and sets the acceleration, deceleration process time, and two times of acceleration, deceleration equate;

2) set the maximum speed of motor acceleration and the maximum speed in the motor accelerator;

3) set the acceleration and deceleration cycle-index;

4) start to carry out the system inertia identification, motor carries out linear Accelerating running with an acceleration time constant, arrives the maximum speed of setting after the acceleration time of setting;

5) with one time deceleration time constant carry out linearity and run slowly, setting-up time arrives rear motor speed and is kept to 0 rev/min;

6) in adding in linearity, subtracting running, carry out the detection of an output current every the unit interval of setting-up time, and this electric current is stored in the electric current register;

7) judgement acceleration and deceleration motion number of times,, if circulation does not reach the number of times of setting, enter flow process 4),, if cycle-index reaches, enter flow process 8);

8) obtain within the circular flow time of setting according to the data of electric current register, driver outputs to the total current of motor;

9) obtain system output torque according to the relation of driver output total current and torque:

System output torque=output current * moment coefficient

Moment coefficient can draw by tabling look-up;

10) according to flow process 9) the output torque of the system that obtains and system operation total time, obtain the servo-drive system average torque;

11), according to acceleration time and the speed set, obtain the mean speed in the system running;

12) rotor inertia of load inertia and motor is regarded as a whole inertia, is carried out the time of acceleration and deceleration motion according to motor mean speed, servo-drive system average torque and system, obtain the value of whole inertia, be electric system inertia:

$(J_M+J_L)=\frac{60\·T_m}{4\·2\mathrm{\π}\·N_m}{t}_r$

In formula: N _mFor motor mean speed, unit: r/min); J _MFor the rotor inertia of motor, unit: Kgm ²J _LFor load inertia, unit: Kgm ²T _mFor the servo-drive system average torque, unit: Nm; t _rFor the total time of system acceleration and deceleration operation, unit: s.

The present invention overcomes in prior art, the problems that the tonnage control model exists in actual use, and the pressure monitoring devices of external special use, do not realize the control of tonnage by the torque of direct control motor.In servo crank presser, the useful torque that motor produces is used for the acceleration of motor shaft inertia, overcomes the friction between friction, slide block guide rail friction and the kinematic pair of motor bearings, overcomes in addition operating force and frrction load and is converted to the moment of resistance on motor shaft.The moment of resistance that is converted on motor shaft is comprised of operating force and frictional force two parts, and frictional force can be ignored with respect to operating force, therefore, can realize by the torque of controlling motor the control to tonnage.

The present invention realizes the control of tonnage by the torque of direct control motor, pressure monitoring devices that need external special use has been simplified the hardware configuration of system greatly, reduced the cost of equipment, simple, convenient, be easy to safeguard, and the tonnage control accuracy reach ± 1%.

Description of drawings

Fig. 1 is the schematic diagram of mechanism of the crank connecting link servo-pressing machine controlled of the present invention.

Fig. 2 is the stressed schematic diagram of connecting rod.

Fig. 3 is motion controller and servo-driver wiring.

The specific embodiment

Servo crank presser comprises motion controller, servo-driver and motor, the pressure control mode of existing servo-pressing machine is all to measure tonnage by pressure monitoring module tonnage instrument or special-purpose pressure measuring device, tonnage feeds back to digital control system with numeral or analog quantity mode, and digital control system realizes reducing or increasing tonnage according to the motion of the tonnage adjusting slider of feedback.The present invention is the pressure monitoring devices of external special use not, realizes the control of tonnage by the torque of direct control motor.different rotational angle residing according to the servo crank presser crank, and the tonnage of technological requirement setting, the maximum motor torque that given servo crank presser is different, control the power of the working motion direction of crank connecting link transmission by the torque of controlling motor, control the tonnage of servo crank presser, wherein, motion controller dynamically calculates the moment of resistance on electric system inertia and motor shaft: for the calculating of electric system inertia, utilize the automatic inertia identification module that servo-driver provides carry out system inertia identification and, recording, by artificial input motion controller, preserved at different position of rotation crank, the moment of resistance on motor shaft is dynamically calculated according to the position of crank and slide block by motion controller, motion controller is tried to achieve the current location of crank and slide block according to the working motion curve, movement velocity and acceleration, calculate current position to crank given given with torque motor, motion controller Negotiation speed/torque mode is sent to servo-driver with the given and given mode with analog quantity or bus of torque in position, the speed/torque control model of utilizing servo-driver to provide, realization is controlled the torque of motor, and then realization is to the control of tonnage.

In the present invention, automatically the method for inertia identification module inertia identification is: regard the rotor inertia of load inertia and motor as a whole inertia, servo-drive system is carried out the linear deceleration motion, draw system output torque and motor mean speed in this section period, obtain the servo-drive system average torque by system output torque,, according to the total time of motor mean speed, servo-drive system average torque and system acceleration and deceleration operation, obtain the value of described electric system inertia again, the specific implementation step is:

1) system is servo enables, and sets the acceleration, deceleration process time, and two times of acceleration, deceleration equate;

2) set the maximum speed of motor acceleration and the maximum speed in the motor accelerator;

3) set the acceleration and deceleration cycle-index;

4) start to carry out the system inertia identification, motor carries out linear Accelerating running with an acceleration time constant, arrives the maximum speed of setting after the acceleration time of setting;

5) with one time deceleration time constant carry out linearity and run slowly, setting-up time arrives rear motor speed and is kept to 0 rev/min;

6) in adding in linearity, subtracting running, carry out the detection of an output current every the unit interval of setting-up time, and this electric current is stored in the electric current register;

7) judgement acceleration and deceleration motion number of times,, if circulation does not reach the number of times of setting, enter flow process 4),, if cycle-index reaches, enter flow process 8);

8) obtain within the circular flow time of setting according to the data of electric current register, driver outputs to the total current of motor;

9) obtain system output torque according to the relation of driver output total current and torque:

System output torque=output current * moment coefficient

Moment coefficient can draw by tabling look-up;

10) according to flow process 9) the output torque of the system that obtains and system operation total time, obtain the servo-drive system average torque;

11), according to acceleration time and the speed set, obtain the mean speed in the system running;

12) rotor inertia of load inertia and motor is regarded as a whole inertia, is carried out the time of acceleration and deceleration motion according to motor mean speed, servo-drive system average torque and system, obtain the value of whole inertia, be electric system inertia:

$(J_M+J_L)=\frac{60\·T_m}{4\·2\mathrm{\π}\·N_m}{t}_r$

In formula: N _mFor motor mean speed, unit: r/min); J _MFor the rotor inertia of motor, unit: Kgm ²J _LFor load inertia, unit: Kgm ²T _mFor the servo-drive system average torque, unit: Nm; t _rFor the total time of system acceleration and deceleration operation, unit: s.

The present invention is integrated into the inertia identification module with the identification of above-mentioned electric system inertia by software, and simple operations can obtain the identification result of inertia.

Implementation step of the present invention is:

1) measure the system inertia of electric system under the crank different angles by automatic inertia identification module: lathe is unloaded, the step angle that crank rotates is set, often walk a step angle and carry out an inertia measurement, and preserve the electric machine rotation angle of this moment and the system inertia of measurement;

2) servo-driver is arranged to the speed/torque control model;

3) the maximum tonnage of servo crank presser is set;

4) the lathe band carries and does working motion, and motion controller is at each control cycle according to maximum tonnage and the residing anglec of rotation of crank, and calculating time processing pressure decomposes the effect torque on crank;

5) the useful motor torque T of motor generation is expressed as

$T\left(t\right)=J_e\frac{\mathrm{dw}\left(t\right)}{\mathrm{dt}}+\mathrm{Bw}\left(t\right)+T_s\left(t\right)---\left(1\right)$

J in formula _e---be converted to the inertia on motor shaft, i.e. step 1) the electric system inertia measured;

B---slide block viscous friction coefficient;

T _s---be converted to the moment of resistance on motor shaft, i.e. step 4) the effect torque that calculates;

W (t)---motor angular velocity

---the motor angular acceleration

Step 4) the current angular acceleration of effect torque, motor that calculates Bring formula (1) into and calculate the needed torque T of motor;

6) step 5) the motor torque T that obtains and motion controller send to servo-driver according to the movement velocity simulation output that working motion curve negotiating PID controller calculates; Wherein, motion controller Negotiation speed/torque mode is sent to servo-driver with the given and given mode with analog quantity or bus of torque in position, and the relation of particular location and speed realizes velocity simulate output by the adjustment of PID controller parameter;

7) servo-driver is controlled velocity of rotation and the output torque of motor according to given speed, torque.

Below illustrate specific embodiment of the invention.

Fig. 1 is the schematic diagram of mechanism of the crank connecting link servo-pressing machine controlled of the present invention, and motor is by the rotation of gear driven crank, and rotatablely moving of crank changes into the rectilinear motion up and down of slide block by connecting rod.Wherein, throw of crankshaft is R, and length of connecting rod is l, and the angle of crank and top dead-centre axis is θ, and the angle of connecting rod and top dead-centre axis is θ ₁

Fig. 2 is the stressed schematic diagram of connecting rod.N ₂Act on the normal force with respect to the crank pivot of connecting rod for crank, T _FAct on the tangential force with respect to the crank pivot of connecting rod for crank; F is operating force, N ₁Act on the positive force of connecting rod for slide block guide rail.

Connect motion controller and servo-driver speed and dtc signal line according to Fig. 3, motion controller is inputted servo-driver with the instruction of aanalogvoltage speed restriction and the instruction of aanalogvoltage torque limit:

1) lathe is unloaded, and slide block is got back to top dead-centre, and the crank anglec of rotation is set to 0 degree, and the operational mode of servo-driver is made as speed control mode;

2) step angle of setting crank is 10 degree, according to gear ratio, calculates to such an extent that the motor anglec of rotation is 50 degree at 1: 5;

3) setting maximum speed in motor acceleration and deceleration process in servo-driver is 300 rev/mins, in 50 degree corners motor by the zero velocity linearity be added to 300 rev/mins of maximal raties again linearity decelerate to zero velocity, the accelerator time is 50/360/300 * 60 * 1000/2=14 millisecond, the moderating process time is also 14 milliseconds, and two times equate;

4) setting acceleration and deceleration iterative motion number of times in servo-driver is 2 times;

5) start to carry out the electric system inertia identification, motor carries out 14 milliseconds of Accelerating runnings, accelerates to 300 rev/mins after 14 milliseconds;

6) then carry out 14 milliseconds and run slowly, 14 milliseconds of rear motor speed are kept to 0 rev/min;

7) complete the operation of preceding step, servo-driver Automatic computing system inertia also shows, records current system inertia and the current crank anglec of rotation of motion controller that servo-driver shows;

8) motor run to the current angle of rotary crank add 10 the degree positions, repeating step 4) to step 7), the 360 degree places until crank rotates a circle;

9) system inertia typing digital control system corresponding to the different rotary angle that records, and preserve;

10) operational mode of change servo-driver is that speed/torque is controlled;

11) motion controller arranges the maximum tonnage 800KN of servo crank presser, crank radius of turn R=18mm, length of connecting rod l=760mm, viscous friction coefficient B=0.01;

12) according to crank anglec of rotation θ, initial datum line is calculated the angle theta of connecting rod and top dead-centre axis take the slide block top dead-centre as angle ₁:

${\mathrm{\θ}}_1=\arcsin \left(\frac{l}{R}\sin \mathrm{\θ}\right);$

13) according to the kinetics relation of toggle illustrated in figures 1 and 2, F, θ and θ ₁The substitution following formula can be tried to achieve equivalence and be arrived the resistance of motor side apart from T _s:

$T_s=F\·[(\frac{\mathrm{Cos}{\mathrm{\θ}}_1}{\mathrm{Cos}(\mathrm{\θ}-{\mathrm{\θ}}_1)}-\frac{\mathrm{Sin}{\mathrm{\θ}}_1}{\mathrm{Sin}(\mathrm{\θ}-{\mathrm{\θ}}_1)})/(\frac{\mathrm{tg}(\mathrm{\θ}-{\mathrm{\θ}}_1)-\mathrm{ctg}(\mathrm{\θ}-{\mathrm{\θ}}_1)}{R}-\frac{\mathrm{Sin}{\mathrm{\θ}}_1}{(l\·{\cos \mathrm{\θ}}_1-R\cos \mathrm{\θ})\·\mathrm{Cos}(\mathrm{\θ}-{\mathrm{\θ}}_1)}-\frac{\mathrm{Cos}{\mathrm{\θ}}_1}{(l\·\cos {\mathrm{\θ}}_1-R\cos \mathrm{\θ})\·\sin (\mathrm{\θ}-{\mathrm{\θ}}_1)})]$

In formula, F is the maximum tonnage that motion controller is set, and other variable implication is same above;

14) the moment of resistance T that calculates _s, motion controller is according to working motion curve calculation motor angular velocity w (t) and angular acceleration out

Viscous friction coefficient B and system are brought formula (1) at the rotary inertia at place, θ angle can obtain current output torque T;

15) with current output torque T divided by maximum motor torque T _max, T _maxFor servo-driver sets according to motor characteristic, then multiply by the maximum output voltage that allows of motion controller, is also the maximum input voltage that allows of servo-driver, is 10V, obtains motion controller and is input to the torque simulate given (T of servo-driver _m/ T _max) * 10V;

This shows, it is exactly that resistance is apart from T that tonnage F is reflected to motor side _s, see step 13) in T _sWith the relational expression of F, and motor torque and resistance are apart from T _sRelation see formula (1), therefore the present invention can realize by the torque of direct control motor the control of tonnage, pressure monitoring devices that need external special use, greatly simplified the hardware configuration of system, reduced the cost of equipment, simple, convenient, be easy to safeguard, and the tonnage control accuracy reach ± 1%.

Claims (3)

1. the compress control method of a servo crank presser, servo crank presser comprises motion controller, servo-driver and motor, it is characterized in that different rotational angle residing according to the servo crank presser crank, and the tonnage of technological requirement setting, the maximum motor torque that given servo crank presser is different, control the power of the working motion direction of crank connecting link transmission by the torque of controlling motor, control the tonnage of servo crank presser, wherein, motion controller dynamically calculates the moment of resistance on electric system inertia and motor shaft:, for the calculating of electric system inertia, utilize automatic inertia identification module that servo-driver provides to carry out system inertia to crank at different position of rotation and identify and preserve, the moment of resistance on motor shaft is dynamically calculated according to the position of crank and slide block by motion controller, the crank that the working motion curve that motion controller is inputted according to the user is tried to achieve and the current location of slide block, movement velocity and acceleration, calculate current position to crank given given with torque motor, motion controller Negotiation speed/torque mode is sent to servo-driver with the given and given mode with analog quantity or bus of torque in position, the speed/torque control model of utilizing servo-driver to provide, realization is controlled the torque of motor, and then realization is to the control of tonnage.

2. the compress control method of a kind of servo crank presser according to claim 1 is characterized in that comprising the following steps:

1) measure the system inertia of electric system under the crank different angles by automatic inertia identification module: lathe is unloaded, the step angle that crank rotates is set, often walk a step angle and carry out an inertia measurement, and preserve the electric machine rotation angle of this moment and the system inertia of measurement;

2) servo-driver is arranged to the speed/torque control model;

3) the maximum tonnage of servo crank presser is set;

4) the lathe band carries and does working motion, and motion controller is at each control cycle according to maximum tonnage and the residing anglec of rotation of crank, and calculating time processing pressure decomposes the effect torque on crank;

5) the useful motor torque T of motor generation is expressed as

J in formula _e---be converted to the inertia on motor shaft, i.e. the electric system inertia of step 1) mensuration;

B---slide block viscous friction coefficient;

T _s---be converted to the moment of resistance on motor shaft, i.e. the effect torque that calculates of step 4);

W (t)---motor angular velocity

---the motor angular acceleration

The current angular acceleration of effect torque, motor that step 4) is calculated

Bring formula (1) into and calculate motor torque T;

6) the motor torque T and the motion controller that step 5) are obtained send to servo-driver according to the movement velocity simulation output that working motion curve negotiating PID controller calculates;

7) servo-driver is controlled velocity of rotation and the output torque of motor according to given speed, torque.

3. the compress control method of a kind of servo crank presser according to claim 1 and 2, the method that it is characterized in that automatic inertia identification module inertia identification is: regard the rotor inertia of load inertia and motor as a whole inertia, servo-drive system is carried out the linear deceleration motion, draw system output torque and motor mean speed in this section period, obtain the servo-drive system average torque by system output torque, again according to the motor mean speed, the total time of servo-drive system average torque and system acceleration and deceleration operation, obtain the value of described electric system inertia, the specific implementation step is:

1) system is servo enables, and sets the acceleration, deceleration process time, and two times of acceleration, deceleration equate;

2) maximum speed in setting motor acceleration and deceleration process;

3) set the acceleration and deceleration cycle-index;

4) start to carry out the system inertia identification, motor carries out linear Accelerating running with an acceleration time constant, arrives the maximum speed of setting after the acceleration time of setting;

5) with one time deceleration time constant carry out linearity and run slowly, setting-up time arrives rear motor speed and is kept to 0 rev/min;

6) in adding in linearity, subtracting running, carry out the detection of an output current every the unit interval of setting-up time, and this electric current is stored in the electric current register;

7) judgement acceleration and deceleration motion number of times,, if circulation does not reach the number of times of setting, enter flow process 4),, if cycle-index reaches, enter flow process 8);

8) obtain within the circular flow time of setting according to the data of electric current register, servo-driver outputs to the total current of motor;

9) obtain system output torque according to the relation of servo-driver output current and torque:

System output torque=output current * moment coefficient

Moment coefficient can draw by tabling look-up;

10) according to flow process 9) the output torque of the system that obtains and system operation total time, obtain the servo-drive system average torque;

11), according to acceleration time and the speed set, obtain the mean speed in the system running, i.e. the motor mean speed;

12) rotor inertia of load inertia and motor is regarded as a whole inertia, is carried out the time of acceleration and deceleration motion according to motor mean speed, servo-drive system average torque and system, obtain the value of whole inertia, be electric system inertia:

In formula: N _mFor the motor mean speed, unit: r/min; J _MFor the rotor inertia of motor, unit: Kgm ²J _LFor load inertia, unit: Kgm ²T _mFor the servo-drive system average torque, unit: Nm; t _rFor the total time of system acceleration and deceleration operation, unit: s.

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