CNC equipment screw gear clearance and pitch error compensation

â–¡ Xiao Nai Kuan inter-s G pitch wrong Qiao compensated CNC equipment screw gear table 1 Table 2 measurement point position mm correction value mm position error (measured) mm corrected position error mm average error mm compensation value compensation data average positive direction negative direction Positive direction negative direction ABCDEF=D-CG=E-CH=(F+G)/21=H/X With the extension of the use time of the numerical control equipment, the lead screw, gear gap and pitch error will change greatly. In order to maintain the machining accuracy of the numerical control equipment, it is an important task to strengthen the equipment management and to correct the backlash and pitch error of the numerical control equipment.

Take 0-MD as an example to talk about the compensation method for backlash and pitch error.

1. The parameters and descriptions related to compensation and the initial tooth gap compensation direction are set to positive direction and 1 is negative direction.

PML1, PML2: Pitch error compensation magnification (used on all axes), the true value is shown in Table 1. BKW: backlash compensation amount, set range compensation time, the distance between two set points, that is, the pitch error compensation point The minimum value of the interval is 8000mi/nn (maximum feedrate compensation stroke = compensation interval x127. That is, each compensation point parameter, the set value is ±7 (error value pm/compensation magnification).

The last digit X, Y, Z, and 4 of the parameter name in the comparison table represent the numerical control axis D. The measurement method and the determination of the compensation data are measured by the dial gauge: the dial gauge is fixed on the bed, and the measurement is performed. The head finger moves on the end face of the shaft to be measured, moving the axis to be measured, so that the dial gauge is zero, and the position display of the control system is also cleared. Use the jog to move the measured axis in the opposite direction until the dial gauge pointer changes. At this time, the amount of displacement displayed by the control system minus the amount of pointer fluctuation is the screw gear clearance of the shaft.

Measured with a dual-frequency laser interferometer: the absolute value of the data difference between the forward measurement data curve and the reverse measurement curve at the commutation, which is the screw gear clearance of the shaft.

When the gap value reaches a certain value, that is, the finishing equipment reaches lOpn, and the roughing equipment is 50Mm, please check whether the screw connection nut is loose.

Pitch Error Compensation Parameter Values ​​The methods commonly used to measure pitch error are block gauge measurement, step gauge measurement, optical reader measurement, and dual-frequency laser interferometer measurement. Each unit can choose according to the actual situation.

It should be noted that when the power supply voltage and frequency are constant, the running performance of the asynchronous motor varies with the load. Therefore, it is not negligible to change the load reasonably to improve the force index of the motor. This is the rationalization and energy saving of production. It is another aspect that complements the rationalization and energy saving of electricity consumption. At the same time, in the development of production and market competition, enterprises must involve adjustment of product structure, production process innovation, optimization of operation methods, transformation or renewal of mechanical equipment and other issues, resulting in load changes and may cause new non-economic operations. Therefore, the economic operation management of the motor is a daily work and a long-term task that coexists with the life of the enterprise. W01.10-10 [Editing Wu Siming] â–¡ Zhou Jiajian excitation generator, given speed nil voltage negative feedback current positive feedback - mIV (current differential feedback number before the 1960s produced gantry planer, most of its electrical drag system uses magnetic flux expansion The machine has a continuous flow motor speed control system, and the electrical control part is very complicated, and there are many components, which are aging, and most of them are eliminated products. It brings great trouble to maintenance. In recent years, due to the high-power thyristor rectifier The application provides possibilities for the technical transformation of these old-fashion planers, but the thyristor is expensive, and the cost of modifying a planer is more than 100,000 yuan. There are two BQ2020s in our factory (the length of the planer is 6m) The gantry planer belongs to this situation. We decided to carry out the technical transformation of the electrical control part of the planer by ourselves. The specific contents are as follows: cancel the magnetic expansion unit, and use a small power controllable voltage regulator to excite the generator to achieve actuation. The voltage regulation of the motor, the feedback control uses the negative feedback of the speed to achieve closed-loop control, thus improving the stability and speed range of the operation.

The planer limit switch is changed from the original mechanical switch to the non-contact proximity switch; the old model DC relay is replaced by a new type of high reliability relay; the excitation generator is eliminated, and the transistor rectifier is used instead; the original control cabinet is deleted. All of the large fixed resistors and adjustable resistors are replaced by three potentiometers. The original speed control system is shown in the figure. The schematic diagram of the improved speed control system is shown.

After the improvement, the control performance of the planer is greatly improved and the effect is remarkable.

The control principle is simplified, the stability and reliability of the operation are improved, and the faults are few; the speed regulation performance is significantly improved, mainly to improve the stability of the low speed operation, and can be used as a guide grinding machine after the improvement; And the excitation generator, thus reducing energy consumption and noise (expanding machine speed is 3000r/min, noise frequency is high).

Through this technological transformation, we have such an experience. In the past, people thought that to improve the old planer, it was necessary to cancel the generator set and replace it with a high-power controlled rectifier power supply to save energy and improve performance. Not always. According to the measurement, the no-load loss of the unit accounts for 12%~15% of the rated power. That is, during the planing process, the unit is also in light load for most of the time. The energy consumption is not a lot of schematic diagrams of the original speed control system. The DC generator set and the planer drive motor have the same operating conditions, and the structural performance and service life are also matched, so it is completely feasible to reserve the generator set. The large-capacity controllable rectification power supply device is not only expensive, but also has a complicated control principle. The technical requirements for the maintenance electrician are correspondingly high, so it is not necessarily cost-effective. The comprehensive cost of our renovation program is only about 25,000 yuan, so the technical performance and economic effect are still very good. The planer has been in operation for almost two years and has been very stable. The axis return to the origin measured by W01.10-121 (determine the error compensation origin). 2 Clear the measurement instrument (table) and control system display position data. 3 Compile and run the automatic start-stop cycle program (function: after running the compensation interval distance, stop the time enough to read the data, then run, and then stop, the number of cycles is the maximum compensation stroke/compensation gap). Read and record each data. Or use the MDI method to read and record each data for each movement compensation interval. After reaching the maximum stroke, return to the measurement and record. Repeat measurement data record table and processing method (Table 3) 1. Record and repeatedly check all parameters of the system before compensation.

Set the following parameters (the setting method is described in general information) Pitch error compensation zero point; Pitch error compensation interval.

After shutting down and returning to the machine origin, take measurements.

Set the measured pitch error compensation amount and backlash compensation amount.

The machine returns to the origin.

Review and record each parameter. W01.10-11 No. 1 Rainbow Road, Yangshi City, 712021 [Edited by Li Wen] SB and Xiongyi 2001NolOm

(Finish)

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