RU2025257C1 - Device for controlling feed drives of two-functional elements of equivalent driving coordinates of gear shaper - Google Patents

Abstract

FIELD: machine-tool manufacture. SUBSTANCE: correcting signal is shaped concurrently with the setting signal for electric motors of both coordinates, said correcting signal being proportionate to the difference of actual speeds of coordinates. Correcting signal of lagging coordinate is added to the control one while that of the leading coordinate is subtracted from control signal. EFFECT: improved design. 2 dwg

Description

 The invention relates to the field of machine tools and can be used to control two equivalent feed drives - the leading coordinates of gears with programmed control, for example gear shaping, for simultaneous processing of two gears with one cutter on two dividing tables.

 A device for controlling drives of two functionally related coordinates is known, in which the drive of the driven coordinate synchronously with the auto-adjustment processes the motion of the leading coordinate [1].

 However, this device cannot be used to control two equivalent leading coordinates, since there is no coordinate subordination between them under the operating conditions.

 A device for controlling the drives of feeds of two equivalent leading coordinates (longitudinal tables) of a gear-shaping machine with programmed control [2]. In this device, the formation of equal in magnitude of the control signals by both coordinates and the simultaneous communication by their electric motor of these coordinates takes place.

 The device comprises a master connected through the first and second power amplifiers, respectively, with the first and second adjustable electric motors, kinematically connected via gearboxes to the actuators of the first and second leading coordinates. On the executive bodies of both equivalent coordinates, the first and second pulse measuring transducers are installed, respectively.

 In the process of functioning of a mechanical system, the speed of movement along any of the coordinates deviates. Speed deviation is a consequence of the deviation of the electric motor and the conditions in the friction pairs of the gearbox and the actuator. Two drives with the same pattern of deviation are not possible.

 In the feed drives of metal cutting machines, where the main type of electric motors are high-torque DC machines, the circular frequency is stabilized by speed feedback (main feedback) and current (additional feedback). To do this, the appropriate feedback sensor, for example, a tachogenerator for speed feedback, is built into the electric motors. However, automatic regulation of the speeds of electric motors relative to a certain value specified by the voltage of the setter cannot ensure the uniformity of movement, i.e., the position of two equivalent executive bodies. This is explained by the fact that typical traditional feedbacks cannot take into account the difference in nodes, friction, and the difference in rigidity of two mechanical systems, i.e., gearboxes and associated executive bodies. As a result, two equivalent leading coordinates, having the same path, move differently, in particular, one of the executive bodies may finish the movement specified by the working conditions earlier. Such non-optimal motion of both equivalent coordinates reduces the accuracy of the functional relationships that include the leading coordinates, and, as a result, reduces the kinematic accuracy of the gears being machined.

 The purpose of the invention is improving accuracy by optimizing the control of two equivalent leading coordinates.

 The invention is based on the fact that when the positions are mismatched on both coordinates, the control signals of the electric motors change simultaneously - for the leading coordinate, the control signal decreases, and for the lagging coordinate it increases. As a result, the mismatch of movements is eliminated simultaneously by slowing down one coordinate and accelerating another. The consequence of this is a decrease in the time constant of the correction signal. For example, with the same time constant for working out each coordinate, the resulting constant is equal to half the time constant of one coordinate. Thus, the speed of error processing increases and the buildup of the control system decreases from the average signal value, which ensures the purpose of the invention.

 The phase discriminator determines the absolute value of the lag of one of the executive bodies, and the sign discriminator determines which of the executive bodies is lagging by setting the sign of the lagging coordinate. By means of the signal from the output of the sign discriminator, two keys are activated, controlled by the same signal in sign. Both keys on this signal report the absolute lag converted to an analog signal into parallel adders, where this signal for the lagging coordinate is added to the reference signal, and for the leading coordinate it is subtracted from the reference signal.

 In FIG. 1 is a block diagram of a feed drive control device; in FIG. 2 is a timing chart.

 To control the drives of the feeds of two equivalent executive bodies, a driving motor control signal is generated. This signal is generated by the setter 1 in the form of an input voltage, which in modern controlled drives of machines varies from zero to several volts. As a setpoint, a power source with a stepwise change in the output voltage can be used, which is typical for feed drives of CNC machines. The setter 1 is connected to the first inputs of the addition of the first 2 and second 3 parallel adders.

 The output of the first 2 parallel adder through a series-connected first position controller 4, the first speed controller 5 and the first power amplifier 6 is connected to the first controlled electric motor 7. The output of the second 3 parallel adder through a series-connected second position controller 8, the second speed controller 9 and the second power amplifier 10 are connected to a second controlled electric motor 11.

 P-controllers are used as position controllers 4 and 8, and PI-controllers are used as speed controllers. Tachogenerators 12 and 13, which are speed feedback sensors, are built into electric motors 7 and 11. The tachogenerators 12 and 13 are connected to the inputs of the speed controllers 4 and 8, respectively. Speed feedback is the main feedback. Feedback on the armature current is also possible.

 Electric motors 7 and 11 by means of gears 14 and 15 are kinematically connected with the executive bodies, for example, longitudinal tables, respectively 16 and 17 of the first and second leading coordinates. On the executive bodies 16 and 17 installed the first 18 and second 19 pulse measuring transducers.

 The output of the first pulse measuring transducer 18 is connected to the first inputs of the phase discriminator 20 and the sign discriminator 21. The output of the phase discriminator 20 is connected via the pulse-to-analog converter 22 to the analog inputs of the first 23 and second 24 keys controlled by negative potential, and the first 25 and second 26 keys driven by positive potential.

 The control inputs of the keys are connected to the output of the sign discriminator 21. The second input of addition and the subtraction input of the first 2 parallel adders are connected to the outputs of the keys 25 and 23, respectively. The second input of addition and the subtraction input of the second 3 parallel adders are connected to the outputs of the keys 24 and 26, respectively.

 The device operates as follows.

 The master signal generated in the master 1 is simultaneously communicated through the first addition inputs of the first 2 and second 3 parallel adders, position controllers 4 and 8, speed controllers 5 and 9, the first 8 and second 10 power amplifiers, respectively, to the first 7 and second 11 electric motors receiving rotational motion.

 Circular frequencies of electric motors independently of each other due to their own feedback on the speed, respectively, the tachogenerator 12 - speed controller 5 and the tachogenerator 13 - speed controller 9 are automatically adjusted.

 Electric motors 7 and 11 through the gears 14 and 15 communicate the movement to the actuators 16 and 17, respectively. As a result, the actuators, due to the symmetry of the driving signal transmission circuit, synchronize with the speed proportional to the given signal.

 Actual speeds and the instantaneous position of the actuators vary due to different friction conditions and different rigidity of the mechanical systems of both actuators. Therefore, in the process of moving, a signal is continuously generated proportional to the difference between the actual positions of the executive bodies for correcting the phase-shift of the movements.

 Pulse measuring transducers 18 and 19 generate pulse signals - analogues of the actual speeds of the actuators 16 and 17, respectively. These signals are fed to the inputs of phase 20 and sign 21 discriminators for comparison. An pulse signal is generated at the output of the phase discriminator, which is proportional in frequency to the absolute difference of the actual positions (speeds) of the actuators. This signal is converted to analog in the pulse-to-analog Converter 22 and is supplied to the analog inputs of the keys 23, 24, 25, 26.

 At the output of the sign discriminator 21, a “-” signal is generated when the second 17 executive organ lags or a + signal when the first 16 executive organ lags. The sign signal from the output of the sign discriminator 21 is fed to the control inputs of the keys 23, 24, 25, 26, controlled by a different sign of the signal. In this case, two keys are opened, controlled by the same signal in sign. For example, when the second executive body 17 lags behind, a negative signal is generated at the output of the sign discriminator 21. This signal opens the keys 23 and 24 controlled by negative potential. Through the key 23, the correction signal is fed to the subtraction input of the first 2 parallel adders, and through the key 24, to the second input of addition of the second 3 parallel adders. As a result, at the output of the first parallel adder 2, the driving signal decreases, and at the output of the second parallel adder 3 increases. The speed of the first executive body 16 is proportionally reduced and the speed of the second executive body is increased.

 When the sign changes at the output of the sign discriminator 21, which corresponds to the lag of the first executive body 16, the keys 25 and 26 open. As a result, the correction signal is simultaneously fed to the second input of addition of the first parallel adder 2 and to the subtraction input of the second parallel adder 3. The speed of the first increases proportionally. executive body 16 and decreases the speed of the second executive body 17.

 Thus, due to the simultaneous influence of the correction signal on the electric motors of both executive bodies, the phase displacement of the movements of these organs and by reducing their movements to an accelerated value is ensured.

PRI me R. To control the feed drives of two longitudinal tables, which are the equivalent leading coordinates of the gear-shaping machine with tangent cutting, on which two wheels are located, which are located symmetrically with respect to the axis of the cutter, a setting signal U 3 _is proportional to the feed, for example, equal to 0.3 mm / two-way, to both drives through the first inputs of addition of the first 2 and second 3 parallel adders. Electrical analog signals f ₁ and f _{2 of the} actual speeds of the first 16 and second 17 executive bodies, respectively, show the lag of the first executive body. This lag in the sign discriminator 21 is converted into a signal f ₃ with the sign "+", and in the phase discriminator 20 into a signal f ₄ , which is converted into an analog signal U _k proportional to the frequency in a pulse-to-analog converter 22, from the output of which this the signal enters the inputs of the keys 23, 24, 25, 26.

The sign signal “+” opens the keys 25 and 26. The signal U _to through the key 25 is fed to the second input of the addition of the parallel adder 2, and through the key 26 this signal is fed to the subtraction input of the parallel adder 3. The resulting signals at the outputs of the parallel adders 2 and 3, respectively U _s + U _to and U _s - U _to . As a result, the movement of the lagging first executive body 16 of the accelerator, and the movement of the leading second executive body 17 is slowed down. When you change the sign at the output of the sign discriminator, which corresponds to the lag of the second executive body 17, the nature of the correction of movements changes to the opposite.

 Thus, the speeds of both coordinates are reduced to the arithmetic average until the lag of one of the executive bodies is reduced to zero. In the limiting case, the intensity of eliminating the mismatch doubles in comparison with the prototype, according to which the mismatch signal is reported to only one, for example, lagging, coordinate. Therefore, by increasing the intensity of eliminating the mismatch, optimization of control of equivalent coordinates is provided.

 The invention in comparison with the prototype provides optimal control conditions of equivalent coordinates. This is achieved due to the fact that at the same time carry out the correction of the control signals of the electric motors of both executive bodies. The nature of the supply of these signals is such that the leading coordinate slows down during the mismatch, and the lagging one accelerates. As a result, the period of working out the mismatch is minimized, which is a condition for optimal control of two equivalent coordinates. With the same time constant for working out the mismatch of each coordinate, the resulting constant will be equal to half the constant of one coordinate.

Claims (1)

 DEVICE FOR CONTROL OF DRIVES OF FEEDS OF TWO EXECUTIVE BODIES OF IDENTIFICALLY LEADING DENTAL SHOP COORDINATES, comprising a gear unit connected in series with a first speed regulator and a first power amplifier with a first adjustable electric motor, which is kinematically connected via a first pulse converter to a first gear unit with a first gear unit in series a second speed controller and a second power amplifier with a second adjustable electrode by a kinematically connected via a second gearbox with a second actuator, on which a second pulse measuring transducer is mounted, and the adjustable motors are covered by negative feedbacks made in the form of the first and second tachogenerators built into the corresponding adjustable electric motors and connected to the inputs of the first and second blocks, respectively comparisons associated with appropriate speed controllers, characterized in that, in order to improve accuracy, the triad is equipped with first and second parallel combiners, first and second position controllers, first, second, third and fourth keys, a pulse-analog converter, a phase discriminator and a sign discriminator, while the first inputs of the addition of parallel summers are connected to the outputs of the setter, the second input of addition and the subtraction input of the first parallel adder is connected respectively to the outputs of the first and second keys and the first key, the second addition input and the subtraction input of the second parallel sum ora are connected respectively to the outputs of the third and fourth keys, the analog inputs of the keys are connected to the output of the pulse-to-analog converter, connected by its input to the output of the phase discriminator, in which the first and second inputs are connected respectively to the first and second pulse measuring transducers, the control inputs of the keys are connected to the output of the sign discriminator, in which the first and second inputs are connected respectively to the first and second pulse measuring transducers, the output The first and second parallel adders are connected to the inputs of the first and second position controllers respectively, connected by their outputs to the inputs of the first and second speed controllers, respectively.

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