Research Journal of Applied Sciences, Engineering and Technology 6(2): 285-288, 2013
ISSN: 2040-7459; e-ISSN: 2040-7467
© Maxwell Scientific Organization, 2013
Submitted: September 22, 2012
Accepted: November 29, 2012
Published: June 10, 2013
Design of High Frequency Power Oscillator Board Based on Rotary Encoder Control
Jiang Shifen and Liang Jiyi
Jiangmen Polytechnic, Guangdong Province, 529090, China
Abstract: Accurate and stable high frequency pulse power supply is studied to improve high-speed wedm machine
tool's efficiency. Regarding to the shortcomings of traditional digital circuit high frequency oscillator board, we
design a high frequency power oscillator board based on rotary encoder control, control accuracy and highfrequency waveform by programming, adjusting the frequency and display. It has six brakes of processing function,
it also includes feedback function of emulsification oil. The high frequency will be shutdown and the emulsification
oil will be changed if there is too much metal dust in emulsification. It has been proved by practice that highfrequency circuit board is simple and reliable and can greatly increase efficiency of wire cutting.
Keywords: High-frequency power oscillation plate, MCU control, rotary encoder, WEDM
MCU detects the number of pulses when turning by
rotary encoder, control the pulse width and between
pulses accurately using the recursive form of position
type PID control algorithm. The high frequency wave
generated from the single chip circuits and the pulse
signal synthesis of high frequency PWM control the
generation after the intermittent pulse wave through the
power amplifier level of the high frequency amplifier
after input to the level. To produce high-frequency
spark cutting work piece, at the same time in the digital
display on the pulse width values. Through the metal
dust sensor test between the work piece and
molybdenum wire cutting and the dust produced cause
a short circuit, feedback adjustment of emulsified fuel
processing liquid level and it can avoid the short and
cause cutting efficiency reduce or even broken wires
(He et al., 2009).
INTRODUCTION
WEDM (Wire Electric Discharge Machine) is
mainly composed of instrument, impulse power,
working liquid cycle system and NC system and
machine accessories and so on. High frequency electric
spark electrical erosion mold piece is used, which is
essential to modern mold processing and it is widely
used in China (Wu, 2008). The performance of line
high-frequency pulse power is the key factor to decide
wire-cutting processing efficiency and processing
quality. Currently, traditional digital circuits with
switch or potentiometer are used by WEDM to cut
work piece by producing high-frequency pulse wave.
For the adjusting frequency of traditional high
frequency oscillation board can't reach the accuracy of
the rotary encoder, it is subjected the restriction of high
frequency accuracy when cutting different kinds of
piece work (Lin, 2003). This study designs a high
frequency power supply through the program control
precision of high frequency vibration plates, the
frequency adjustment can show, six processing function
gear, with rotary encoder tuning frequency, can
improve the efficiency of the line shears. Its output
sockets and traditional high frequency board
arrangement replaces the digital circuit structure of the
traditional high frequency oscillation board completely.
Hardware design of the high frequency board
control circuit:
Control design of the revolving encoder: Rotary
encoder is a high precision Angle measuring sensor,
with high resolution, fast response and other
characteristics, widely used in position or Angle for the
object of the control system. This design chooses
general incremental rotary encoder, incremental
encoder axis rotation, which have corresponding phase
output. The rotation of the direction of discrimination
and pulse of the increase and decrease of the quantity,
the microcontroller programming realize. The starting
point count can be arbitrary set and can achieve more
laps of infinite accumulation and measurement. When
the pulse has been fixed, the need to improve the
resolution, with 90° can use phase difference of two
signals to the original pulse number time’s frequency
(Qiu and Zhu, 2000). Its input waveform is shown in
Fig. 2.
Overall design of the high frequency board of pulse
power in WEDM: In this study, overall control
diagram of WEDM high frequency plate is shown as
Fig. 1. It consists of the single chip microcomputer
control system module, detection feedback control
circuit module, button and rotary encoder input module,
the high frequency wave packet circuit module, the
high frequency wave output and power circuit module
and intelligent energy-saving power supply module.
Corresponding Author: Jiang Shifen, Jiangmen Polytechnic, Guangdong Province, 529090, China
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Res. J. Appl. Sci. Eng. Technol., 6(2): 285-288, 2013
Keyboard model
Isolating
circuit
model
MCU
control
model
Rotary encoder
model
Arcing
circuit
Driving
circuit
The spark gap
Arcing detection
module
High frequency
model
Network
commiunication
model
Power amplifier
circuit
Intelligent energysaving power
Alarm circuit
Display model
Isolating circuit
model
Working liquid
feedback module
Metal dust
sensor
Fig. 1: Overall control diagram of WEDM high frequency plate
Fig. 2: Rotary encoder wave
P4
VCC
R3
Clkout2
330
R2
Clkout1
K1
2
1
VCC
Switch-a
Switch-b
30pF
2
C2
Relay-SPDT
VCC
1K
U3
R10
1K
R0
1K
R1
330
R12
Switch-b
Switch-a
330
P1
1
2
3
4
5
Rotay encoder
S1
SW-PB
C1
10uF
Y2
24Mhz
DS1
1
C3
30pF
M1
M2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
P2.2 12LE5616AD VDD
P2.3
P2.1
RST/VPD
P2.0/PWM2
P3.0/RXD
P1.7
P3.1/TXD
P1.6
XTAL2
P1.5
XTAL1
P1.4
P3.2/INT0
P1.3
P3.3/INT1
P1.2
P3.4/T0
P1.1/T
P3.5/T1/PWM1
P1.0
P2.4/PWM3 P3.7/PWM0
P2.5
P2.7
VSS
P2.6
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS2
DS3
D1
D2
D3
D4
D5
D6
D7
R18
R19
1K
1K
C6
0.01uF
M3
M4
12LE5616AD
1
Y1
24Mhz
1
VCC
C5
2
0.01uF
U1B
15
U1A
C4
2
3
16
14
1K
U1C
9
6
10
103
R9
11
U1D
7
8
R21
330
1
2
3
4
U4
NC Vcc
Vf+ Vo
VfVe
NC GND
6N137
R11
1K
8
7
6
5
R27
330
CLK
C7
104
VCC
Fig. 3: Circuit diagram of master control module
button selection process work piece type and processing
method function. Four digital tubes are to show the high
processing mode and pulse width (Yang et al., 2002).
Circuit part principle diagram is shown in Fig. 3.
Design of microcontroller master control module:
The master control module circuit is designed by
STC12 series microcontroller, low power consumption,
high anti-static, strong anti-interference. It has PMW
function, 24 MHz crystals, completely meet the design
requirements. Spin encoding output pulse signal access
port P2.3 and single chip microcomputer P2.4 pin, use
of rotary encoder fine-tuning pulse intermission and
pulse width, digital pipe display frequency, light touch
Software design of system: The whole system process
design is shown in Fig. 4. The system firstly, initialized,
including timer 0 and 1 and timer PWM initialization
procedures. Next, it scans the keyboard and starts the
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Res. J. Appl. Sci. Eng. Technol., 6(2): 285-288, 2013
initialization
Key
processing
Digital display
key_value=?
Thick
processing
Medium
thickness
processing
Thin
processing
key_value=?
Finish
machining
Medium
precision
processing
Rough
machining
Y1=0
Rotary encoder
Y2=0
Frequency fit?
Alarm
Confirm output
LED2
LED1
Fig. 4: Flow chart of the whole system
Table 1: Three processing type and processing method of interveinal and proportion
Processing type
Processing methods
-------------------------------------------------------------------------------------------------------------------------------------------Think
Medium
Thin
Rough
Medium
Finish
Intrapulse
60us
40us
20us
40us-60us
20us-40us
4us-20us
Duty ratio
1:14
1:8
1:6
1:8-1:9
1:6-1:7
1:4-1:5
Rotary encoder can click "1, 0" progressive signal input and realized accurate adjustment
digital display. Judge whether the choice of the key
processing type, carries on the corresponding
processing program. E.g., key choice of method is thin
processing. Then, starts the rotary encoder, continues to
choose occupies empties compared, determines the
selected interveinal after numerical, accurate to 1 us
and confirm the output pulse waveform after required,
at the same time indicator emit light (Duan et al.,
2002).
Which accounts for empty and pulse width and the
pulse than between value as shown in Table 1? Such as
press finishing mode, select processing proportion,
levorotatory for 1:4, dextral for 1:5, selected after
proportion by rotary encoder confirm key, enter finetuning, transferred to the best value to press the rotary
encoder ok button, right now have waveforms output,
the LED indicator emit light.
System operation and test results: The high
frequency board designed by this study is convenient
for operation; turn the choice of processing the three
types, thin, middle, thick, respectively. For example,
the choice of thin processing, it is a fixed value for 20
us, pulse width and the pulse of the ratio between all
can not be adjusted, if want to try to adjust, can choose
pure, medium and thick, three processing mode.
CONCLUSION
This design employs revolving encoder to fine-tune
frequency, controls precision of high frequency by
program and high plasticity, function and parameter any
programming adjustment, fine-tuning rotary encoder
adjust pulse frequency between the precise. The use of
revolving encoder has solved the biggest problem in
287
Res. J. Appl. Sci. Eng. Technol., 6(2): 285-288, 2013
fine-tuning, improved the machining efficiency,
prevented wire broken and saved the cost. The high
frequency oscillation with rotary encoder board of high
frequency power can be used in most of WEDM
indeed.
Lin, C.P., 2003. Thread cutting wire break fault reason
analysis. Die Mould Manufacture, 6: 56-57.
Qiu, H.Z. and Z.F. Zhu, 2000. Realized of a high
precision rotary encoder microcontroller counts
circuitry. Comput. Autom. Meas. Control, 3:
50-51.
Wu, D.Y., 2008. WEDM Processing Technical FAQ
Application. Mechanical Industry Press, Beijing,
pp: 1-40.
Yang, B., Z.M. Weng, S.J. Cao et al., 2002. A new type
of electrical discharge machining power. Electro
Mach. Mould, 3: 20-23.
REFERENCES
Duan, W.Y., B. Yang and W.Y. Wu, 2002. Study on
the power supply of EDM in digital control.
Electro Mach. Mould, 3: 16-18.
He, Q.M., S.L. Yang and S.D. Wang, 2009.
Development of high frequency inductive heat
power supply based on microcontroller. J. Yantai
Univ., Nat. Sci. Eng. Edn., 22(1): 42-45.
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