摘要:
The present invention relates to motor control at the time of reversal of direction of feed axes of a machine tool using a servomotor. The present invention includes a disturbance torque estimating unit for estimating a disturbance torque and estimating a frictional torque. The value in a speed loop integrator is divided into a frictional torque component and an acceleration torque component. An integrator target value for the time of reversal of motor rotation is obtained in accordance with the acceleration torque component and a value obtained by inverting the sign of the frictional torque component. Backlash acceleration correction is effected using a value obtained by applying a certain offset to a speed command so that the integrator target value is reached, as a backlash acceleration value. In estimating the frictional torque, a ratio of torque constant to inertia is estimated automatically, and the frictional torque is estimated by using this ratio. Since proper backlash acceleration correction can be effected, quadrant projections are minimized.
摘要:
A method of controlling a servomotor, characterized by faster convergence of both positional deviations and velocity deviations, higher responsibility as well as an improved resistivity against a disturbance, and being free from any mechanical resonance. An adjustment gain G is increased when a torque command Tc1 received from a conventional velocity control is small, whereas the adjustment gain G is decreased when the torque command Tc1 is large. A torque command Tc2 obtained by multiplying the Tc1 to the output from the velocity control section by the adjustment gain G is supplied to the servomotor. The gain is to be heightened in the case where the positional deviation and velocity deviation are both small and the torque command Tc1 is also small, to thereby ensure a higher responsibility and a rapid convergence. Moreover, the gain is to be suppressed when the torque command Tc1 is large, thus preventing the occurrence of a mechanical resonance.
摘要:
In a controller where a contour machining is performed through a synchronous control between a mechanically movable portion (servo axis) driven by a servo motor and a main shaft (spindle axis) driven by a spindle motor, the position of the servo axis and the position of the spindle axis are collected at the same timing for each predetermined cycle and are stored. The position data of the servo axis and the spindle axis stored are converted to obtain a machining contour shape data, and the shape obtained is displayed on a display device of a personal computer or the like.
摘要:
A method for estimating a load acting on a machine tool and controlling a life of the machine tool based on the estimated load. When predetermined machining is effected on a predetermined workpiece, a disturbance load torque acting on a motor for a spindle or a motor for a feed shaft is estimated by a disturbance estimating observer. When the estimated disturbance load becomes not lower than a set reference value, a timer is reset and started. If the estimated disturbance load torque is kept not smaller than the set reference value until the timer reaches a predetermined set time, a tool change command is issued to stop the machining. Since the tool life is determined in accordance with the magnitude of the load acting on the tool, the tool life is controlled objectively and accurately.
摘要:
To control a servo motor, after the sign of a shift command is inverted, a first offset amount Vmo is added to a speed command during a period the motor rotates by the amount of "a" so that inversion of sign of an integral value of the speed loop is made to occur earlier, thereby accelerating the reversal of the direction of the motor. Then, after the motor has rotated by an amount "b", a second offset amount Vto is added to the speed command, thereby causing the motor to generate a torque that is large enough for an object connected to the motor to start moving to overcome the frictional force. The first offset amount is determined based on a value of an integrator in the speed loop at the time the direction of the shift command is inverted so that the servo motor is reversed by the correct amount. The second offset value is reversed determined based on the acceleration at the moment of inversion, so that its value is optimized corresponding to the frictional force. As a result, the delay of motion at the time of reversion is small, and it becomes possible to reduce a protrusion occurring on a cut surface in the transition of machining from one quadrant to another quadrant.
摘要:
A servo motor controller having: a frequency identification section that performs analysis based on a frequency response method and identifies the frequency of a disturbance exhibiting a specified phase lag; an input/output gain identification section that identifies the input/output gain at the frequency identified by the frequency identification section; and a magnification factor resetting section that resets an adjustment magnification factor by performing a specified operation on a ratio between the identified input/output gain and a specified target value of the input/output gain.
摘要:
A method for changing a force control gain expressed as a ratio of force error to velocity command value in a control circuit performing a force control of a servo motor driving a die cushion disposed opposite to a slide in a press machine. The method includes: obtaining a difference between a displacement of the slide and a displacement of the die cushion in a state in which the slide and the die cushion collide with and are exerting force on each other; detecting the force when the difference of the displacements is obtained; calculating a spring constant of a structural portion based on a proportionality between the difference of the displacements and the force, when regarding the structural portion including the slide and the die cushion as an elastic structure; and changing the force control gain based on the spring constant using a fixed proportionality that exists between the force control gain and a reciprocal of the spring constant.
摘要:
A motor drive apparatus 1 having a dynamic braking circuit 5 for producing a deceleration torque utilizing a braking force caused by a synchronous motor 4 acting as a generator when the synchronous motor 4 is deenergized, is equipped with a dynamic braking circuit fault detection capability, and comprises: a DC power supply 2 which is obtained by rectifying input AC power; voltage application means 2, 3, 10, 11 for applying a voltage to the windings of the synchronous motor 4 and to the dynamic braking circuit 5 for a predetermined length of time by switching power transistors A to F connected to the DC power supply 2; current detection means 6 for detecting the value of a current flowing from the power transistors A to F; and fault checking means 11 for checking the dynamic braking circuit 5 for the presence or absence of a fault, based on the current value detected by the current detection means 6 and on a predefined threshold value. With this configuration, detection of faults in the dynamic braking circuit is accomplished without requiring the addition of a contact signal or a control circuit.
摘要:
A control apparatus for controlling a die cushion mechanism including a servo-motor as a drive source and producing a force adapted to be applied to a slide in a press machine. The control apparatus includes a force commanding section for commanding a force to be produced by the die cushion mechanism; a force detecting section for detecting the force produced by the die cushion mechanism; a motor-speed detecting section for detecting an operating speed of the servo-motor; a slide-speed detecting section for detecting a moving speed of the slide; and a force controlling section for executing a force control on the servo-motor, based on a force command value commanded by the force commanding section, a force detected value detected by the force detecting section, a motor-speed detected value detected by the motor-speed detecting section and a slide-speed detected value detected by the slide-speed detecting section.
摘要:
A control device (10) for a die cushion mechanism that produces a force for a slide (24) in a press machine, comprising slide velocity command-forming means (61) for forming a velocity command for the slide (24), die cushion velocity command-forming means (62) for forming a velocity command for said die cushion (20), and velocity relation calculation means (65) for calculating a velocity relation between the velocity of the slide and the velocity of the die cushion based on a rate of increase (dF) in the force produced between the slide and the die cushion immediately after the collision of the slide with the die cushion. The cushion velocity command-forming means forms the velocity command for the die cushion based upon the slide velocity command formed by the slide velocity command-forming means and upon the velocity relation calculated by the velocity relation-calculation means. This makes it possible to form an optimum velocity command for the slide and/or the die cushion.