Keywords: digital display shaft angle absolute value measurement single chip application
Data Display Reconstruction for Axial Angle
Measurement of Stator Turning and Boring Machine
Liu Fang Li Ping Yang Guang
Abstract In this paper, the axis angle index measurement of stator turning and boring machine Tools is realized by using 8031 ​​micro-computer,open a new way to high accuracy the numerical display technical recinstruction.
Key Words: numerical display reconstruction;axis angle absolute value measure;application of micro-computer
1 Introduction
The stator car boring machine of Harbin Electric Co., Ltd. is mainly used for the production of turbo-generator stator frames. The original measurement of shaft angle division was measured according to the principles of optical reflection and projection. The human eye has a low resolution, coupled with the limitations of the measurement instrument itself, lower measurement accuracy, cumbersome work, and error proneness. In order to improve the accuracy and increase the reliability of the measurement, we chose the SJF-01 digital precision indexing instrument to measure the shaft angle. The instrument is simple to operate and intuitive, which not only improves the measurement accuracy, but also reduces the chance of error.
2 Technical performance and indicators
After the stator car boring machine shaft angle indexing measurement system is digitally modified, the operator only needs to press the electric switch as required, and the rotation angle of the machine tool spindle will be displayed in digital form. The display mode of the instrument is in degrees, minutes, seconds, and decimals. It is divided into two rows of upper and lower displays. It can be arbitrarily selected according to user requirements; its resolution is 2′′ and the measurement accuracy is 2.5′′; the machine speed should be less than 30r. /min; Absolute zero optional; power supply is AC220V ± 5%; operating temperature is best between 0 °C ~ 40 °C.
3 How does the SJF-01 digital indexer work?
3.1 Signal Acquisition SJF-01 type digital indexing instrument information collection, using the JX130 absolute shaft angle encoder as the angular displacement measuring element, two coaxial installation, mounted on the indexing gear shaft. The encoder has 24 jacks and needs to collect 24 signals. Because the amplitude of the signal collected by the encoder is not enough, we use a single-supply four operational amplifier LM324 to amplify the signal, and the amplified signal is input as the input terminal of the voltage comparator LM339, and after processing by the comparator, the desired signal is generated. Feed into the motherboard.
3.2 Principle of digital display instrument The SJF-01 digital precision indexing instrument adopts the more advanced 8031 ​​single-chip microcomputer as the central processor in the industrial control. The external is equipped with an auxiliary circuit, including the address latch and external program memory. , Decoder, A/D, D/A converter, buffer, driver, etc. jointly complete the measurement and display of the axis angle division. The hardware block diagram of this instrument is shown in Figure 1.
Figure 1 hardware schematic of precision indexer
The 8031 ​​single-chip microcomputer is a computer made up of a central processing unit (CPU), a random access memory (RAM), a timer/counter, parallel and serial I/O ports integrated on a single chip, and it has strong versatility. It is also quite specific and suitable for various control systems. There are multiple I/O interfaces in the chip to facilitate system expansion and information exchange. On-chip timers/counters are also included. There is no program memory in the 8031 ​​microcontroller, and it requires an external program memory EPROM2732. The system expansion of the single-chip microcomputer is carried out through the off-chip pins of the single-chip microcomputer. 8031 microcontroller has 40 pins on the chip, VCC (40 feet) and VSS (20 feet) are connected to +5V power and ground, respectively. XTAL1 (19 feet) and XTAL2 (18 feet) are connected to both ends of the crystal. RST/VPP (19-pin) is used for power-on reset or power-off protection of the microcontroller. The ALE/PROG (30-pin) is the latch enable signal for the address latch 74LS373. PSEN (29-pin) outputs a negative pulse as a read strobe signal to the program memory when accessing the off-chip program memory EPROM2732. The EA/VPD (pin) must be grounded or connected low in the 8031 ​​microcontroller. P0.0 to P0.7 (39 pins to 32 pins) are called P0 ports. When accessing the external program memory EPROM2732 as an address/data multiplex port, it provides 8-bit address lines and 8-bit bidirectional data buses in a time-sharing manner. . P2.0 port P2.0 ~ P2.3 as the external program memory EPROM2732 high four address bus. P2.4 to P2.7 of P2 port are used as input terminals of the decoder. The P1.0 pin of port P1 is used as the output end of the pulse signal. P1.3 and P1.4 are used to control the AD7574.
8031 one-chip computer can only deal with the digital quantity like the ordinary digital computer and can't deal with analog quantity directly, so must carry on A/D, D/ A to change. The former is used for the 8031 ​​single-chip microcomputer, which controls or drives the actuator. In order to ensure the accuracy of the conversion results, A/D and D/A conversions must achieve sufficient accuracy; when processing the rapid inspection process, sufficient speed must be ensured. In this instrument, the AD7574 is used to perform A/D conversion. Various types of A/D converter chips are equipped with data output pins, start pins, conversion end pins, and so on. The 8031 ​​microcontroller expansion A/D converter is to handle the hardware connection between the pin and the CPU. In addition, in the SJF-01 digital precision indexing instrument, also selected LF398 as a sample holder, AD7502 as an analog switch, AD581 as a reference voltage regulator, UA1489 as a level converter, 74LS04 as an inverter, 8282 As a driver and other peripheral auxiliary circuit.
3.3 software structure <br> The software program of this instrument adopts assembly language, the execution speed of the procedure is fast, save the storage space. The mnemonics and label addresses are used to facilitate the programming of the program, without having to memorize the machine code of the instructions and without having to perform address calculations while writing the program. Software block diagram shown in Figure 2.
Figure 2 software precision block diagram
4 Conclusion
After the modification of the stator car boring machine of Harbin Electric Co., Ltd., the operator has worked very convenient. Simply pressing the electric switch will show the axis angle index on the instrument. After the requirements are reached, the drill hole can be positioned. After the transformation of the machine tool processing a machine stand 4 to 5 days earlier than before, saving manpower, shortened the duration, reduced product costs, increased economic efficiency, the initial realization of the automatic control of the machine. Because the instrument uses an 8031 ​​single-chip microcomputer as the central processor and the sampling is accomplished by coaxially mounting two absolute shaft angle encoders to complete the signal acquisition, its accuracy and reliability are higher than other digital display instruments.