CN102091850B - Aluminum Alloy Digital Welding Machine with Smooth Transition Double Pulse Parameters - Google Patents

Abstract

The invention discloses an aluminum alloy digital welding machine with smooth transition double-pulse parameters, which comprises a power main circuit, a main control motherboard, a main control MCU, a wire feeding drive circuit, an ARM control man-machine interaction system and a hardware PID controller, wherein the hardware PID controller, the wire feeding drive circuit and the main control MCU are arranged on the main control motherboard, the wire feeding drive circuit is connected with the main control MCU, the hardware PID controller is connected with the main control MCU and a control port of the power main circuit, the current input end of the power main circuit is connected with commercial power, and the current output end of the power main circuit is connected with a welding load. The invention adopts the MCU + ARM as a control core, realizes the driving control of a main circuit by generating PWM through a hardware PID controller, reduces the workload of the main control MCU, and the main control MCU quickly and stably completes the tasks of welding process flow control and double-pulse waveform database management, thereby improving the welding efficiency and realizing the stable welding of the aluminum alloy from small current to large current.

Description

Aluminum Alloy Digital Welding Machine with Smooth Transition Double Pulse Parameters

technical field

The invention relates to the technical field of double-pulse aluminum alloy digital welding machines, in particular to an aluminum alloy digital welding machine with smooth transition double-pulse parameters.

Background technique

With the development of power electronics technology and digital technology, high-performance single-chip microcomputers (MCUs) have made epoch-making breakthroughs in terms of functions, processing speed and processing capabilities, and the theory and implementation methods of digital signal processing have achieved unprecedented development. One of the fastest growing disciplines. After the high-end single-chip microcomputer MCU was successfully introduced into the field of welding power source control, it provided the possibility to further improve the performance of the welding process and provided opportunities for trying new welding processes. With its stability, repeatability, real-time digital signal processing, flexible programming, and large-scale integration, MCU has become the best choice for welding power supply control and digital signal processing, making digital and intelligent arc welding power sources emerge as the times require.

In foreign countries, internationally renowned welding equipment companies represented by FRONIUS in Austria, EWM in Germany, and KEMPPI in Finland have developed a series of digital welding machine systems with expert databases, and the welding prices are expensive. At present, the domestic digital welding machine is in the research and development stage, mainly Tangshan Panasonic, Shanxi Xingyun, Beijing Times, Shanda Aotai and other companies are developing, and some of them have launched digital welding machine products. In terms of double-pulse aluminum alloy welding, the aluminum alloy welding machines produced by European countries represented by the Austrian FRONIUS company are relatively mature, and the welding process is stable. However, domestic manufacturers are still exploring the dual-pulse welding technology of aluminum alloys, and have not yet made a substantial breakthrough, mainly because they have not yet found the inherent regularity in the design of the double-pulse parameters. The reason is mainly because there are many welding parameters of the double pulse, and a large number of process tests are required for proper matching between them, while the aluminum alloy dissipates heat quickly, and the welding process is extremely unstable; in addition, the arc length is unstable, and the welding wire is easy to burn back. Short circuit, low melting point and easy evaporation of welding wire lead to very unstable arc state. the

Contents of the invention

The purpose of the present invention is to provide an aluminum alloy digital welding machine with smooth transition double-pulse parameters in view of the deficiencies in the prior art. The main control MCU of the welding machine can quickly and stably complete the welding process control and double-pulse waveform database management tasks. High welding efficiency realizes stable welding of aluminum alloy from small current to high current.

The purpose of the present invention is achieved through the following technical measures:

Aluminum alloy digital welding machine with smooth transition double pulse parameters, including power main circuit, main control motherboard, main control MCU, wire feeding drive circuit, ARM control human-computer interaction system, hardware PID controller, hardware PID controller, feeding The wire drive circuit and the main control MCU are set on the main control motherboard, the wire feeding drive circuit is connected to the main control MCU, the hardware PID controller is connected to the control port of the main control MCU and the power main circuit, and the current input terminal of the power main circuit is connected to the mains Connection, the current output terminal of the power main circuit is connected with the welding load, and the ARM control human-computer interaction system is connected with the main control MCU.

Among them, the power main circuit includes passive harmonic suppression rectification filter circuit, IGBT full-bridge inverter circuit, intermediate frequency transformer, rectification filter circuit, the input terminal of passive harmonic suppression rectification filter circuit is connected with mains, passive harmonic suppression The output end of the rectification and filtering circuit is connected to the current input end of the IGBT full-bridge inverter circuit, the current output end of the IGBT full-bridge inverter circuit is connected to the input end of the intermediate frequency transformer, and the output end of the intermediate frequency transformer is connected to the rectification and filtering circuit. The output terminal of the circuit is connected with the welding load.

Among them, it also includes a current sampling circuit and a voltage sampling circuit. The input terminal of the hardware PID controller is connected to the current sampling circuit and the voltage sampling circuit. The hardware PID controller feeds back the voltage information collected by the voltage sampling circuit and the current information collected by the current sampling circuit. to the main control MCU. the

Among them, the 3846 drive circuit is also included. The 3846 drive circuit includes the main control chip U3. The 5 pins of U3 are connected to the hardware PID controller. Connection, pin 4 of U3 is connected to the primary current feedback terminal of the IGBT full-bridge inverter circuit, pin 16 of U3 is connected to the input terminal of the protection signal, the voltage signal is processed by the main control MCU and transmitted to U3 through the hardware control PID controller, U3 According to the primary current feedback information fed back by the IGBT full-bridge inverter circuit received by the 4-pin, and the current-voltage feedback signal received by the 5-pin of U3 after the operation and processing of the main control MCU, the output voltage is jointly adjusted to drive the IGBT full-bridge The switch tube of the inverter circuit.

Among them, the model of the main control chip U3 of the 3846 driving circuit is UC3846, and the 3846 driving circuit realizes the limited bipolar soft switching control IGBT full-bridge inverter circuit.

Among them, the main control MCU adopts the fixed-frequency and variable-frequency calculation method of the double-pulse MIG welding waveform based on the mathematical model design to realize the fine adjustment from small current to large current. During the adjustment process from small current to large current, the number of strong and weak pulses and The size of the base value changes adaptively according to the size of the average current.

Among them, the fixed-frequency and variable-frequency calculation method of the dual-pulse MIG welding waveform designed based on the mathematical model is as follows: Let T be the period of a pulse group, T strong be the strong pulse time within a pulse group period, and T weak be the period of a pulse group The weak pulse time within , t1 is the base value time of the strong pulse group, t2 is the base value time of the weak pulse group, a is the base value current of the strong pulse group, b is the base value current of the weak pulse group, c is the peak current, n1 is the number of pulses in the strong pulse group, n2 is the number of pulses in the weak pulse group, f represents the frequency of double pulse modulation, and I is the average current; T weak=T strong=T/2=500/f in a pulse group cycle ;

First set the initial values of n1 and n2, and the unit pulse time is t ms, then there are;

                      

                      

get the average current

；

;

如下： When the peak current of the strong burst, the peak current of the weak burst, the base current of the strong burst, and the base current of the weak burst are fixed, there is a one-to-one correspondence between n1, n2 and t1, t2, and n1, n2 are gradually increased , then t1 and t2 gradually decrease, taking the subfunction of current

as follows:

    ；  m为大于0的常数，m为a或b，均小于c；

; m is a constant greater than 0, m is a or b, both of which are less than c;

but ;

斜率变陡至某一位置时趋于稳定，按照一定规律逐步加大n1，n2，则相对应t1、t2 逐步减小，从而导致电流逐步增大，并且电流增大速度逐渐加快，从而实现焊接电流可连续调节，且随着电流的逐步加大其增加更快。 That is, as x gradually decreases,

When the slope becomes steeper to a certain position, it tends to be stable. If n1 and n2 are gradually increased according to a certain rule, the corresponding t1 and t2 will gradually decrease, which will lead to a gradual increase in current, and the speed of current increase will gradually accelerate, thus realizing welding The current is continuously adjustable and increases more rapidly as the current is stepped up.

Among them, the ARM control human-computer interaction system includes ARM module, CPLD module, key, encoder, LED and digital tube display module, LED and digital tube display module, encoder and CPLD module connection, key, CPLD module and ARM module connection, The ARM module is connected with the SCI interface of the main control MCU.

Among them, the main control MCU model is STC89C58RD+.

The beneficial effect of the present invention is that: the aluminum alloy digital welding machine with smooth transition double pulse parameters includes a power main circuit, a main control motherboard, a main control MCU, a wire feeding drive circuit, an ARM control human-computer interaction system, and a hardware PID controller, The hardware PID controller, the wire feeding drive circuit, and the main control MCU are set on the main control motherboard, the wire feeding drive circuit is connected to the main control MCU, the hardware PID controller is connected to the control port of the main control MCU, and the power main circuit, and the power main circuit The current input terminal is connected to the mains, the current output terminal of the power main circuit is connected to the welding load, and the ARM control human-computer interaction system is connected to the main control MCU. The present invention adopts MCU+ARM as the control core, and realizes the driving control of the main circuit through the PWM generated by the hardware PID controller, which greatly reduces the workload of the main control MCU, and the main control MCU of the welding machine can quickly and stably complete the welding process control and The dual pulse waveform database management task improves the welding efficiency and realizes the stable welding of aluminum alloy from small current to high current.

Description of drawings

Fig. 1 is a control system structural diagram of the present invention;

Fig. 2 is a power main circuit diagram of the present invention;

Fig. 3 is 3846 driving circuit diagrams of the present invention;

Fig. 4 is main control MCU structural diagram of the present invention;

Fig. 5 is a wire feeding circuit diagram of the present invention;

Fig. 6 is a block diagram of the hardware structure of the human-computer interaction system of the present invention;

Fig. 7 is the parameter schematic diagram of the double pulse current waveform diagram of the invention;

Fig. 8 is the software flow chart of the invented aluminum alloy double-pulse welding machine software system based on the mathematical model;

Fig. 9 is the double pulse waveform during the small current of the present invention;

Fig. 10 is the double pulse waveform during the medium current of the present invention;

Fig. 11 is the double pulse waveform of the present invention at high current.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

This embodiment provides an aluminum alloy digital welding machine with smooth transition double pulse parameters, including a main power circuit, a main control motherboard, a main control MCU, a wire feeding drive circuit, an ARM control human-computer interaction system, a hardware PID controller, and a hardware PID The controller, wire feeding drive circuit, and main control MCU are set on the main control motherboard, the wire feeding drive circuit is connected to the main control MCU, the hardware PID controller is connected to the main control MCU, and the control port of the power main circuit, and the current input of the power main circuit The terminal is connected to the mains, the current output terminal of the power main circuit is connected to the welding load, and the ARM control human-computer interaction system is connected to the main control MCU. The present invention adopts MCU+ARM as the control core, and realizes the driving control of the main circuit through the PWM generated by the hardware PID controller, which greatly reduces the workload of the main control MCU, and the main control MCU of the welding machine can quickly and stably complete the welding process control and The dual pulse waveform database management task improves the welding efficiency and realizes the stable welding of aluminum alloy from small current to high current.

The main power circuit of this embodiment includes a passive harmonic suppression rectification and filtering circuit, an IGBT full-bridge inverter circuit, an intermediate frequency transformer, and a rectification and filtering circuit. The output end of the wave suppression rectification filter circuit is connected to the current input end of the IGBT full-bridge inverter circuit, the current output end of the IGBT full-bridge inverter circuit is connected to the input end of the intermediate frequency transformer, and the output end of the intermediate frequency transformer is connected to the rectification filter circuit. The output end of the rectification filter circuit is connected with the welding load.

This embodiment also includes a current sampling circuit and a voltage sampling circuit. The input terminal of the hardware PID controller is connected to the current sampling circuit and the voltage sampling circuit. The hardware PID controller detects the voltage information collected by the voltage sampling circuit and the current information collected by the current sampling circuit. Feedback to the main control MCU. the

This embodiment also includes a 3846 drive circuit, the 3846 drive circuit includes the main control chip U3, the 5 pins of U3 are connected to the hardware PID controller, the 14 pins, 11 pins, and 4 pins of U3 are input to the control signal of the IGBT full-bridge inverter circuit The pin 4 of U3 is connected to the primary current feedback terminal of the IGBT full-bridge inverter circuit, and the pin 16 of U3 is connected to the input terminal of the protection signal. After the voltage signal is processed by the main control MCU, it is transmitted to U3 through the hardware control PID controller. According to the primary current feedback information fed back by the IGBT full-bridge inverter circuit received by pin 4 of U3, and the current and voltage feedback signal received by pin 5 of U3 and processed by the main control MCU, the output voltage is jointly adjusted to drive the IGBT full bridge. The switching tube of the bridge inverter circuit.

The model of the main control chip U3 of the 3846 driving circuit in this embodiment is UC3846, and the 3846 driving circuit realizes the limited bipolar soft switching control of the IGBT full-bridge inverter circuit.

The main control MCU of this embodiment adopts the fixed-frequency and variable-frequency calculation method of the double-pulse MIG welding waveform designed based on the mathematical model to realize the fine adjustment from small current to large current. The number and base value are adaptively changed according to the average current.

The ARM control human-computer interaction system of the present embodiment comprises ARM module, CPLD module, button, encoder, LED and digital tube display module, LED and digital tube display module, encoder are connected with CPLD module, button, CPLD module and ARM module Connection, the ARM module is connected to the SCI interface of the main control MCU.

The model of the main control MCU in this embodiment is STC89C58RD+.

In this embodiment, the technological program control of the aluminum alloy double pulse welding process and the double pulse waveform control expert database system can be realized. Based on 3846 chip control, it adopts mature limited bipolar soft switch. As shown in Figure 3, PWM drive can be generated only by a given output voltage, which can be regarded as a "black box" to realize V-PWM conversion, coupled with primary current protection, it is stable and reliable. The hardware PID driver greatly reduces the workload of the main control MCU, and the main control MCU can quickly and stably complete process control and data management tasks. The main control motherboard is the core part of the dual pulse welding machine hardware. The purpose of setting up the peripheral operational amplifier circuit and the wire feeding circuit is to output accurate and stable double pulse signals to the driver board, and at the same time match the wire feeding speed of the appropriate current, so as to achieve unified welding.

The fixed-frequency and variable-frequency calculation method of the double-pulse MIG welding waveform designed based on the mathematical model in this embodiment is specifically: let T be the cycle of a pulse group, T strong be the strong pulse time in a pulse group cycle, and T weak be a pulse The weak pulse time in the group cycle, t1 is the base value time of the strong pulse group, t2 is the base value time of the weak pulse group, a is the base value current of the strong pulse group, b is the base value current of the weak pulse group, and c is the peak current Size, n1 is the number of pulses in the strong pulse group, n2 is the number of pulses in the weak pulse group, f represents the frequency of double pulse modulation, I is the average current; T weak=T strong=T/2=500 in a pulse group period /f;

First set the initial values of n1 and n2, and the unit pulse time is 2ms, then there are,

                       

    

                       

    

get the average current

，

,

如下： When the peak current of the strong burst, the peak current of the weak burst, the base current of the strong burst, and the base current of the weak burst are fixed, there is a one-to-one correspondence between n1, n2 and t1, t2, and n1, n2 are gradually increased , then t1 and t2 gradually decrease, taking the subfunction of current

as follows:

    ；

;

m is a constant greater than 0, m is a or b, both of which are less than c;

but ;

That is, as x gradually decreases, When the slope becomes steeper to a certain position, it tends to be stable. If n1 and n2 are gradually increased according to a certain rule, the corresponding t1 and t2 will gradually decrease, which will lead to a gradual increase in current, and the speed of current increase will gradually increase. Based on the mathematical model The designed calculation method of fixed frequency and variable frequency of double-pulse MIG welding waveform realizes the continuous adjustment of welding current, and it increases faster with the gradual increase of current.

The double-pulse parameter mathematical modeling method of constant frequency modulation current in this embodiment. As shown in Figure 7, the commonly used double-pulse modulation frequency f = 3.3 Hz is taken as an example to illustrate the working principle of the mathematical modeling of fixed-frequency double-pulse parameters, T strong = T weak = T/2 = 500/3.3 ms, T _strong , _Tweak are the strong burst time and weak burst time in one burst period respectively; the unit pulse time is 2ms.

t1, t2 are the base value time of strong burst and weak burst respectively, n1, n2 are the number of pulses in strong burst and weak burst respectively, a, b, c are the base value current of strong burst respectively, The magnitude of the base current of the weak pulse group and the magnitude of the peak current. From Figure 7, according to the relationship between n and t, it is brought into the current expression:

Available:

It is easy to know from the above expression that under the condition of fixing the peak current of the strong and weak pulse group and the magnitude of the base value current, t1 and t2 become the two factors that determine the magnitude of the welding current. However, because t1 and t2 have problems of intuition and visual error in the reading of welding waveform acquisition feedback, the difficulty of design is increased. From Figure 7, it can be seen that there is a one-to-one correspondence between n1, n2 and t1, t2. At the same time, n1 and n2 are convenient and intuitive to read test waveform feedback, and both n1 and n2 are integers, which can greatly improve the computing efficiency of the chip. , and more importantly, it simplifies the programming of the expert database and greatly enhances the readability of the program. Therefore, select n1, n2 as the independent variable of the continuous adjustable current.

如下： In order to meet the goal of increasing the current gradually, we can set n1 and n2 to gradually increase, then t1 and t2 will gradually decrease, and take the sub-function of the current

as follows:

      m为大于0的常数，m为a或b，均小于c；

m is a constant greater than 0, m is a or b, both of which are less than c;

；  but

;

斜率变陡至某一位置时趋于稳定。 That is, as x gradually decreases,

The slope becomes stable at a certain point.

By reasonably setting the initial value of the number of strong and weak pulses n1 and n2, and gradually increasing n1 and n2 according to a certain rule, the corresponding t1 and t2 will gradually decrease, resulting in a gradual increase in current and a gradual increase in the speed of current increase . Based on this, this model theoretically realizes that the welding current can be adjusted continuously, and it increases faster with the gradual increase of the current, so as to achieve the purpose of humanized adjustment. Thus, the feasibility of developing the expert database for double-pulse MIG welding of aluminum alloy under the condition of constant frequency is demonstrated.

In this embodiment, the mathematical modeling method of double-pulse parameters with constant frequency-variable average current is assuming that the low-frequency frequency is f, and the remaining double-pulse parameters are as described above, similar to the fixed-frequency modeling idea, the easy-to-get equation:

                                        

                                        

It can be seen from the above formula that the frequency factor of the current magnitude under the variable frequency condition cancels out, which is completely consistent with the equation under the constant frequency condition. Therefore, when other parameters of the double-pulse waveform remain unchanged, the change of the frequency does not affect the adjustment of the current magnitude.

It can be obtained from this that the adjustment of the low-frequency frequency does not affect the adjustable current range of the double-pulse MIG welding, thereby realizing the frequency conversion technology. the

In terms of parameter design of frequency conversion technology, n1 and n2 are the main independent variables, and t1 and t2 can be determined by the frequency and the established n1 and n2, so that the continuous adjustment of low frequency frequency under different average pulse currents can be designed.

In this embodiment, the low-frequency modulation frequency can be changed under the condition that the pulse average current remains unchanged, that is, under the condition of maintaining a certain welding speed, according to the needs of the operator, the double-pulse low-frequency frequency can be changed to obtain beautiful and high-quality welds at the same time. The width of the fish scale pattern of the weld can be adjusted to meet the needs of different occasions, so that the aluminum alloy double pulse welding machine can meet the requirements of maturity, system and productization.

It realizes the continuous and precise adjustment of pulse average current from small current to large current under the condition of fixed frequency and variable frequency, and can also realize the "humanized" adjustment effect of slow adjustment speed of small current and fast adjustment speed of large current in the welding process. The adjustment effect is mainly based on the pre-designed mathematical model in the software to automatically match the parameter configuration of the corresponding current, which can be obtained through the operation and amplifier of the peripheral hardware circuit. It has been verified by experiments that the dual-pulse aluminum alloy welding machine designed by the patent of the present invention can obtain clear fish scale patterns, the welding process is stable, and the weld seam is formed beautifully.

The aluminum alloy double-pulse digital welding machine involved in the patent of the present invention is based on the continuous adjustable change of the base values a and b of the strong and weak pulse group according to a certain rule, and assists in adjusting the number of strong and weak pulses n1 and n2, which can effectively Expand the range of welding current, so as to realize the continuous adjustment of a wide range of welding current. At the same time, in the transition stage of strong and weak pulses, the pulse base value adopts a gradual change method, which makes the transition of strong and weak pulses smoother and more stable in the welding process.

The parameters of the double pulse are optimized, the pulse time is selected as 2ms, and the pulse current is 250A. By adjusting the values of n1 and n2 according to a certain rule, the welding current can be changed stepwise from small current to high current, but the continuous change of current cannot be realized. As the number of pulses n1 and n2 increase to a certain number, the number of pulses is relatively dense. Under the condition of fixed low-frequency frequency, it is not advisable to continue to increase the number of pulses, that is, when the current reaches a certain size Continuing to increase the current is a difficult thing.

Based on the basic values a and b of the pulse group, the continuous adjustable change is carried out according to a certain rule, and the auxiliary adjustment of the number of pulses n1 and n2 can effectively expand the welding current range, so as to achieve the purpose of continuously adjusting the welding current in a wide range .

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The invention calculates the pulse base value gradient in the strong and weak pulse transition based on a mathematical model, thereby realizing smooth strong and weak pulse group transformation, and compared with the conventional strong and weak pulse direct transformation method, it ensures aluminum alloy welding in the strong and weak pulse transformation The stability of the process.

2. In the present invention, when adjusting the small and medium double-pulse current, the adjustment step is smaller and the adjustment is more precise. When the large double-pulse current is adjusted, the adjustment step is larger and the required adjustment current value is reached faster, which can realize the pulse current voltage during the conversion process of strong and weak pulse waveforms. The smooth transition of the waveform ensures the stability of the aluminum alloy welding process, and the current adjustment is more humane than the ordinary double pulse parameter adjustment method.

3. The double-pulse aluminum alloy welding machine waveform expert database system established based on the mathematical model of the present invention obtains clear fish scale patterns on the digital welding machine, and is a novel method for establishing the digital welding machine expert database.

As shown in Figure 1, the system includes rectification and filtering circuit, IGBT full-bridge inverter main circuit, control circuit, wire feeding drive, human-computer interaction system and other parts. Basic design principle: The relatively mature 3846 driver chip is used to realize the limited bipolar soft switching control IGBT full-bridge inverter main circuit. As the core of process control, high-performance main control MCU mainly completes over-current protection, over-voltage protection, over-temperature protection, current setting, voltage setting, wire feeding speed setting, process logic sequence control, serial communication, data storage, expert System generation and management functions. Using ARM+CPLD mode, the encoder, keys, LED lights, meters and serial port communication on the control panel.

As shown in Figure 2, the three-phase AC of 380V and 50Hz is rectified and filtered by the three-phase rectifier bridge to form a low-ripple high-voltage DC of about 550V, which is then supplied to the main circuit of the IGBT full-bridge inverter and the main transformer T1 for DC-AC conversion . The full-bridge inverter circuits Q1, Q2, Q3, and Q4 are alternately turned on with driving waveforms provided by the control circuit, and then stepped down by the transformer T1 to become an intermediate frequency voltage of 20KHz. Then the rectification and filtering circuit composed of D1 and D2 rectifies it into direct current, and then through the filtering effect of reactance and capacitance, it provides the required energy for the welding arc load.

As shown in Figure 3, the current and voltage feedback signal is input to pin 5 of UC3846 after calculation and processing, and the primary current feedback signal is input to pin 4 of UC3846 to jointly adjust the output voltage; pin 11 and pin 14 are two completely inverted PWM signals Output; pin 16 is the protection signal input pin. When the voltage exceeds 350mV, the output pulse is turned off to protect the switching tube of the IGBT full-bridge inverter main circuit from being damaged by overcurrent; C12 and R24 can set the inverter operating frequency to 20kHz.

As shown in Figure 4, STC's high-performance MCU 89C58RD+ is used as the main control chip. This single-chip microcomputer is a new generation of super anti-interference, high-speed, and low-power consumption products launched by STC. It has the following characteristics: The instruction code is fully compatible with the traditional 8051 Single-chip microcomputer, the working frequency can reach above 50MHz. The configuration includes 36 I/O ports, 32K Flash program storage space, 16K+ E2PROM, on-chip integrated 1280-byte RAM, ISP function, UART, 8 A/D channels, watchdog, and internally integrated MAX810 dedicated reset circuit wait.

As shown in Figure 5, the window comparator in the "welding torch inching wire feeding signal circuit" in the figure has the following characteristics: (1) The input voltage at C is above 10V, that is, when no button is pressed, both D and E are (2) When the input voltage at C is 5V~10V, press the jog wire feeding button, at this time D is low level, and E is high level; (3) When the input voltage at C is at When 0~5V, press the welding torch switch, at this time D is high level, and E is low level. It can be seen from the above characteristics that the welding torch signal and the jog wire feeding signal can realize their functions well through this circuit.

As shown in Figure 6, LM3S818 is used as the control core, combined with CPLD to realize the input of encoder signals, the control of LED lights, and the scanning of buttons, and communicate with the main control chip DSP by using RS232 serial bus and GPIO pins.

As shown in Figure 7, t1 and t2 are the base time of the strong burst and weak burst respectively, n1 and n2 are the number of pulses in the strong burst and weak burst respectively, and a, b, c are the strong bursts respectively Group base value current size, weak pulse group base value current size, peak current size.

As shown in Figure 8, according to the above-mentioned mathematical model, the double-pulse database of aluminum alloy experts was designed and tested. After a large number of process tests, it was shown that: only need to rotate the current setting knob from small to large, the double-pulse welding under the fixed frequency design scheme The current can cover all currents accurate to 1A in the range from 55A to 300A, which proves that the accuracy of the mathematical model expert database is sufficient to meet the continuously adjustable requirements of double-pulse production welding current.

As shown in Figure 9, for small currents, the number of strong bursts and weak bursts is relatively small, and the corresponding base value times are relatively wide, and the strong and weak bursts are relatively sparse on the current waveform. At the same time, both the base current and the peak current are small.

As shown in Figure 10, the medium current waveform is relatively dense, and the base current and peak current values also increase.

As shown in Figure 11, the high current waveform is denser, and the base current and peak current values further increase. At the same time, the above design ideas must ensure that the frequency of the double-pulse low-frequency modulation remains unchanged.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand , the technical solution of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (7)

1. the aluminum alloy digital welding machine with smooth transition double-pulse parameters, it is characterized in that: comprise power main circuit, main control backplane, main control MCU, wire feed drive circuit, ARM controls man-machine interactive system, hardware PID controller, hardware PID controller, wire feed drive circuit, main control MCU is arranged at main control backplane, wire feed drive circuit is connected with main control MCU, hardware PID controller and main control MCU, the control port of power main circuit connects, power main circuit current input is electrically connected to city, the current output terminal of power main circuit is connected with weld load, ARM controls man-machine interactive system and is connected with main control MCU,

Described power main circuit comprises that passive harmonic suppresses current rectifying and wave filtering circuit, IGBT full bridge inverter, intermediate-frequency transformer, current rectifying and wave filtering circuit, the input that passive harmonic suppresses current rectifying and wave filtering circuit is electrically connected to city, the output that passive harmonic suppresses current rectifying and wave filtering circuit is connected with the current input terminal of IGBT full bridge inverter, the current output terminal of IGBT full bridge inverter is connected with the input of intermediate-frequency transformer, the output of intermediate-frequency transformer is connected with current rectifying and wave filtering circuit, and the output of current rectifying and wave filtering circuit is connected with weld load;

Described aluminum alloy digital welding machine also comprises current sampling circuit, voltage sampling circuit, hardware PID controller input is connected with current sampling circuit, voltage sampling circuit, and hardware PID controller detects by the information of voltage of voltage sampling circuit collection, current sampling circuit the current information gathering and feeds back to main control MCU.

2. the aluminum alloy digital welding machine with smooth transition double-pulse parameters according to claim 1, it is characterized in that: also comprise 3846 drive circuits, 3846 drive circuits comprise main control chip U3, 5 pin of U3 are connected with hardware PID controller, 14 pin of U3, 11 pin, 4 pin are connected with the control signal input of IGBT full bridge inverter, 4 pin of U3 are connected with the primary current feedback end of IGBT full bridge inverter, 16 pin of U3 are connected with guard signal input, voltage signal transmits into U3 by hardware PID controller after main control MCU is processed, the primary current feedback information that the IGBT full bridge inverter feedback that U3 receives according to 4 pin is come, and the current/voltage feedback signal after the calculation process of main control MCU received of 5 pin of U3, common regulation output voltage drives the switching tube of IGBT full bridge inverter.

3. the aluminum alloy digital welding machine with smooth transition double-pulse parameters according to claim 2, it is characterized in that: the model of the main control chip U3 of 3846 drive circuits is UC3846,3846 drive circuits are realized the soft switch of finite both and are controlled IGBT full bridge inverter.

4. the aluminum alloy digital welding machine with smooth transition double-pulse parameters according to claim 3, it is characterized in that: what main control MCU adopted dipulse MIG weld ripples shape based on Design of Mathematical Model determines frequency and frequency conversion computational methods, realize little electric current to the meticulous adjusting of large electric current, at little electric current, to strong and weak pulse number in the adjustment process of large electric current and base value size, according to average current size adaptation, change.

5. the aluminum alloy digital welding machine with smooth transition double-pulse parameters according to claim 4, it is characterized in that: the dipulse MIG weld ripples shape based on Design of Mathematical Model determine frequency and frequency conversion computational methods are specially: establish the cycle that T is an impulse train, T is by force the flash time in the impulse train cycle, it a little less than T, is the weak burst length of an impulse train in the cycle, t1 is flash group's the base value time, t2 is the base value time of weak impulse train, a is flash group background current, b is weak impulse train background current, c is peak current level, n1 is pulse number in flash group, n2 is pulse number in weak pulse group, f represents double pulse modulation frequency, I is average current, in impulse train cycle T weak=T is strong=T/2=500/f,

First set n1, n2 initial value, the unit pulse time is t ms, has;

Obtain average current

；

When flash group peak point current, weak pulse punching group peak point current, flash group background current, weak impulse train background current are fixedly time, there is relation one to one in n1, n2 and t1, t2, establishes n1, and n2 strengthens gradually, t1, t2 reduce gradually, the subfunction of obtaining current

as follows:

; M is greater than 0 constant, and m is a or b, is all less than c;

;

Along with x reduces gradually,

slope steepening tends towards stability when a certain position, according to certain rule, progressively strengthen n1, n2, corresponding t1, t2 progressively reduce, thereby cause electric current progressively to increase, and electric current is pushed the speed and accelerated gradually, can regulate continuously thereby realize welding current, and along with its increase of progressively increasing of electric current is faster.

6. according to the aluminum alloy digital welding machine with smooth transition double-pulse parameters described in claim 1-5 any one, it is characterized in that: ARM controls man-machine interactive system and comprises ARM module, CPLD module, button, encoder, LED and charactron display module, LED and charactron display module, encoder are connected with CPLD module, button, CPLD module are connected with ARM module, and ARM module is connected with the SCI interface of main control MCU.

7. the aluminum alloy digital welding machine with smooth transition double-pulse parameters according to claim 6, is characterized in that: main control MCU model is STC89C58RD+.

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