CN203091930U - Welding machine with short circuit electric arc molten drop control function - Google Patents

Abstract

The utility model discloses a welding machine with the function of short-circuit arc droplet control, which is used for metal gas shielded welding. Electrode and workpiece, when the output voltage Uinv of the inverter is at a very low level in this welding current loop, and the welding current presents a sawtooth rising trend at the same time, another reverse voltage source is connected through external control . The welding machine provided by the utility model with the function of short-circuit arc droplet control adopts the sampling frequency synchronized with the pulse signal of the trigger frequency of the inverter to sample, and the instantaneous value of the welding voltage obtained is very real and effective. The opening timing of triggering the reverse voltage source is closer to the time point of the actual welding short-circuit interval, which significantly reduces the splash of liquid metal during the welding process, thereby enhancing the safety of operation, reducing costs and improving production efficiency.

Description

Welding machine with short-circuit arc droplet control function

technical field

The utility model relates to a welding machine with the function of short-circuit arc droplet control.

Background technique

Gas metal arc welding (GMAW) is a surface surfacing method that joins one or more metal materials together by means of welding or brazing. During the welding process, it is necessary to provide an external protective gas atmosphere, and the filling material can be wire or strip metal. The role of the welding power source is to continuously melt the filler material as required. The welding process includes two time intervals: the arc burning interval and the short circuit interval. In the arc combustion zone, with the heat of the arc, the filling material is continuously melted to form molten droplets. As the filler material continues to move toward the workpiece, the droplet becomes larger and larger. Finally, the droplet contacts with the welded pool, forming a short circuit and entering the short circuit area. The short circuit causes the current to increase rapidly, and the increased current will cause the short-circuited liquid metal connecting bridge to be disconnected, and the arc will be ignited again and return to the arc burning zone. In the short-circuit section, the liquid metal has completed the transfer from the end of the welding wire to the workpiece, and in this section due to the action of a large current, a large amount of energy is generated, and the timing of re-strike is completely random. At the last moment of the short-circuit interval, instantaneous high current and high voltage often coexist, resulting in undesirable spatter in welding. The spatter mainly occurs at the moment when the liquid metal section bridge is disconnected and the arc is re-ignited.

Utility model content

Purpose: In order to overcome the deficiencies in the prior art, the utility model provides a welding machine with the function of short-circuit arc droplet control, which solves the defects of the prior art, reduces the splash of liquid metal in the welding process, and enhances the safety of operation performance, reduce costs and increase production efficiency.

Technical solution: In order to solve the above-mentioned technical problems, the technical solution adopted in the utility model is:

A welding machine with a short-circuit arc droplet control function, including an inverter welding power supply module, a welding piece, an inverter control part, a reverse voltage source, a reverse voltage source control part, a voltage sensor, a current sensor, and parameter settings device;

The inverter welding power supply module is connected with the welding parts to form a welding circuit, the inverter control component is connected with the inverter welding power supply module to control the output of the welding power supply, and the reverse voltage source controls the component through the reverse voltage source The control can be connected to the welding circuit in series with the weldment; the voltage sensor is connected in parallel with the weldment for measuring the instantaneous value of the welding voltage, and the current sensor is connected in series with the weldment for measuring the instantaneous value of the welding current; the parameter setting device and The reverse voltage source control part is connected, and is used for setting the set value of current and voltage in the welding process; the voltage sensor and the current sensor are respectively connected with the inverter control part and the reverse voltage source control part at the same time, and the The inverter welding power supply module, the inverter control part and the reverse voltage source control part are connected to each other and synchronized through the Syn signal.

The inverter welding power supply module includes an inverter connected to a power supply, and the inverter is a PWM pulse width modulation inverter.

The welded piece includes a welding electrode and a workpiece; two ends of the inverter welding power module are respectively connected with the welding electrode and the workpiece to form a welding circuit.

The inverter welding power supply module is a power supply obtained from the power grid, through a PWM (pulse width modulation) inverter circuit that works synchronously through a three-phase rectifier bridge and a synchronous clock Syn, to provide input to the inverter, and the secondary of the inverter After the stage is rectified, the two ends of the output are respectively connected to the welding electrode and the workpiece to provide the current and voltage required for welding.

Between the inverter welding power supply module and the welding electrodes, a smoothing reactor and a line equivalent inductance are serially connected in series.

A current sensor is connected in series between the workpiece and the inverter welding power supply module, one path of the current sensor is directly connected to the workpiece through a first switch, and the other path is connected to the workpiece through a series-connected reverse voltage source and a second switch; The first switch and the second switch are switched by the reverse voltage source control part.

The first switch and the second switch are IGBTs or MOSFETs.

The voltage sensor is used to measure a representative voltage value in the instantaneous value of welding voltage.

The current sensor is used to measure a representative current value in the instantaneous value of welding current.

A microcontroller or a DSP (digital signal processing) controller is installed in the inverter control part, the reverse voltage source control part and the parameter setting device.

Beneficial effects: the welding machine with short-circuit arc droplet control function provided by the utility model adopts a sampling frequency synchronous with the pulse signal of the trigger frequency of the inverter to sample, and the instantaneous value of the welding voltage obtained is very real and effective, and at the same time Using this signal to trigger the opening timing of the reverse voltage source is closer to the time point of the actual welding short-circuit interval, the more accurate the timing of the current reduction, the more appropriate the magnitude of the decline, and the better the welding spatter can be controlled; In the short-circuit interval, when the welding current and welding voltage have the typical value of the short-circuit bridge disconnection, the welding current and voltage will drop suddenly, so as to control the energy input during splashing, thereby reducing the splashing of liquid metal during welding and enhancing the operation Safety, reduce costs, improve production efficiency. the

Description of drawings

Fig. 1 is the circuit schematic diagram of the present utility model;

Fig. 2 is the curve diagram of welding voltage U and welding current I corresponding to two intervals of welding of prior art;

Fig. 3 is the curve diagram of welding voltage U and welding current I corresponding to two intervals of the utility model welding;

Fig. 4 is a waveform diagram of the voltage Uinv output by the inverter in the present invention.

In the figure: inverter welding power supply 1, inverter control part 2, first switch 3, second switch 4, reverse voltage source 5, reverse voltage source control part 6, smoothing reactor 7, line equivalent inductance 8. Welding electrode 9, workpiece 10, voltage sensor 11, current sensor 12, parameter setting device 13.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described further.

As shown in Figure 1, it is a welding machine with short-circuit arc droplet control function, including inverter welding power supply module 1, welding parts, inverter control part 2, reverse voltage source 5, and reverse voltage source control part 6. A voltage sensor 11, a current sensor 12, and a parameter setting device 13; the inverter welding power module 1 is connected with the welding parts to form a welding circuit, and the inverter control part 2 is connected with the inverter welding power module 1 for Control the output of the welding power supply, the reverse voltage source 5 can be connected in series with the welding piece to the welding circuit through the control of the reverse voltage source control part 6; the voltage sensor 11 is connected in parallel with the welding piece for measuring the instantaneous value of the welding voltage, The current sensor 12 is connected in series with the weldment, and is used to measure the instantaneous value of the welding current; the parameter setting device 13 is connected with the reverse voltage source control part 6, and is used for setting values of current and voltage during the given welding process; The voltage sensor 11 and the current sensor 12 are connected to the inverter control part 2 and the reverse voltage source control part 6 respectively at the same time, and the inverter welding power supply module 1, the inverter control part 2 and the reverse voltage source control part 6 Interconnections are synchronized via the Syn signal. The inverter welding power supply module 1 includes an inverter connected to a power supply, and the inverter is a PWM pulse width modulation inverter. The welding piece includes a welding electrode 9 and a workpiece 10; the two ends of the inverter welding power module 1 are respectively connected with the welding electrode 9 and the workpiece 10 to form a welding circuit. The inverter welding power supply module 1 is a power supply obtained from the power grid, through a three-phase rectifier bridge and a synchronous PWM pulse width modulation inverter circuit synchronously working with the synchronous clock Syn, to provide input to the inverter, and the secondary of the inverter After rectification, both ends of the output are respectively connected to the welding electrode 9 and the workpiece 10 to provide the current and voltage required for welding. Between the inverter welding power supply module 1 and the welding electrode 9, a smoothing reactor 7 and a line equivalent inductance 8 are serially connected in series. A current sensor 12 is connected in series between the workpiece 10 and the inverter welding power supply module 1. One path of the current sensor 12 is directly connected to the workpiece 10 through the first switch 3, and the other path is connected to the reverse voltage source 5 connected in series and the second The switch 4 is connected to the workpiece 10 ; the first switch 3 and the second switch 4 are controlled by the reverse voltage source control part 6 . The first switch 3 and the second switch 4 are IGBTs or MOSFETs. The voltage sensor 11 is used to measure a representative voltage value in the instantaneous value of welding voltage. The current sensor 12 is used to measure a representative current value in the instantaneous welding current value. A microcontroller or a DSP controller is installed in the inverter control unit 2 , the reverse voltage source control unit 6 and the parameter setting device 13 . the

The welding machine provided by the utility model has the function of controlling the droplet of the short-circuit arc. The alternating current input from the power grid is converted by the inverter, and one end is output to the first switch 3 to directly connect with the workpiece 10 to form the first welding current loop, and the inverter The other end of the welder is connected to a second welding current loop composed of a smoothing reactor 7, a line equivalent inductance 8 and a welding electrode 9. The current impact generated by the smoothing reactor 7 and the line equivalent inductance 8 passes through the inverter Solder the freewheeling diode inside the power module 1 to release it. The other current loop is the reverse voltage source 5 controlled by the reverse voltage source control part 6. When the first preset condition is met, the reverse voltage source voltage source can be connected in series to the current loop to satisfy the second preset condition. When necessary, disconnect the reverse voltage source from the welding circuit. The inverter welding power supply module 1, the inverter control part 2 and the inverter work synchronously through the Syn signal. The voltage sensor 11 is responsible for collecting the welding voltage, and the current sensor 12 is responsible for collecting the welding current; the collected current and voltage are respectively transmitted to the inverter control part 2 and the reverse voltage source control part 6, and the parameter setting device (13) is responsible for setting the welding process The first preset condition and the second preset condition in . The workpiece 10 is connected to the negative pole, and we refer to the voltage on the workpiece 10 as a reference level. A reverse voltage source 5 can be connected in series in the current loop to be a DC voltage source, and the polarity is marked with + and - as shown in the figure. The reverse voltage source 5 can be connected to the current loop via the first switch 3 and the second switch 4 as required. The first switch 3 and the second switch 4 are interlocked switches, and the reverse voltage source 5 can be switched through the pair of interlocked switches, connected to the current loop or bypassed. When the reverse voltage source 5 needs to be connected, the first switch 3 is turned off, and the second switch 4 is turned on at the same time. In contrast, when the reverse voltage source 5 does not need to be connected, the first switch 3 is closed, and at the same time the second switch 4 is turned off, so that the reverse voltage source 5 is bridged. The parameter setting device 13 is used to set the set values of current and voltage: set voltage US set, and set current IS set, the size of the two set values is obtained through external operation instructions, the two Values are related to wire diameter, wire type, shielding gas type and welding method used.

When in this welding circuit, the output voltage Uinv of the inverter is at a very low level, and the welding current presents a sawtooth rising trend at the same time, another reverse voltage source 5 is controlled by the reverse voltage source control part 6. Connected in series to the welding circuit, during the welding process, the typical value curve of the welding voltage and current is sampled in real time through the voltage sensor 11 and the current sensor 12, and the instantaneous value of the welding voltage synchronized with the trigger frequency of the inverter is obtained and stored. The output current of the inverter can be adjusted according to the needs. In the two intervals of welding, the voltage characteristics, power output characteristics and impedance characteristics of the inverter can be adjusted according to the needs. In the interval, it is possible to work in different control types. When the first preset condition occurs in the welding process, the control system will connect the reverse voltage source to the current loop; when the second preset condition occurs, the control system will disconnect the reverse voltage source from the welding current loop. During the trigger period t1 of the inverter voltage output, the instantaneous value Ut1 of the representative welding process voltage can be measured; during the stop period t2 of the inverter voltage output, the representative welding process voltage Ut1 can be measured Instantaneous value Ut2. The first preset condition and the second preset condition can be related to one or more of the following parameters: the instantaneous value of welding current, the product of welding current & welding voltage instantaneous value, the ratio of welding current & welding voltage instantaneous value, The welding voltage instantaneous value Ut1 during the inverter voltage output trigger period, the welding voltage instantaneous value Ut2 during the inverter voltage output stop period, welding process parameters, such as light radiation, sound field change, electric field change and magnetic field change; here, No. The judgment and execution of one pre-set condition and the second pre-set condition can be realized by means of part of the program software.

The instantaneous value acquisition data of the welding voltage is divided into two variables. The first variable is that the real-time welding voltage value of the inverter output pause time t2 can be accurately obtained by triggering the synchronous pulse of the inverter. Another variable is to obtain the real-time welding voltage value at the triggering time t1 of the inverter through the triggering synchronous pulse of the inverter. By monitoring the above two variables. When the instantaneous value of the measured voltage presents a pre-defined condition ("triggering condition of the reverse voltage source"), the reverse voltage source is connected to the current loop. Pre-defined conditions need to be determined according to the process environment. Other current and voltage characteristics in the welding process are used as subordinate parameters and as a reference for judging.

One of the most favorable places of the utility model is that the spatter of welding is significantly reduced. The output adjustable amplitude range of the reverse voltage source is controlled from 0V to the upper limit of the output capability of the reverse voltage source. By controlling the magnitude of the reverse voltage source, the sudden change rate di/dt of the welding current can be affected, thereby reducing welding spatter to the greatest extent. At the same time, it is also stipulated that the turn-on condition of the reverse voltage source can obtain a set of trigger conditions according to sequence and statistics. When the second trigger condition ("end of droplet transfer") is met, the reverse voltage source is disconnected from the current loop. This trigger condition is directly related to the value of the current. The end of the peak process of welding current is used as the basis for judgment. At the same time, the product and ratio of welding current and welding voltage can also be used as the basis for judgment. In fact, other welding parameters, such as changes in the brightness of the welding arc, changes in the sound wave during the welding process, and changes in the electric and magnetic fields of the welding arc can also be taken into consideration as relevant parameters.

In order to timely and accurately judge the "triggering condition of the reverse voltage source", the following judgment method can be adopted: continuously compare two measured values, and when the difference between the two values exceeds a predetermined value, the condition can be considered to be met. Another triggering method is: we can obtain the actual value of the welding voltage from the real-time measured welding voltage, and compare this actual value with the typical voltage characteristic value of a given short circuit as a basis. At the same time, for the above two judging methods, you can specify a duration that the welding voltage must reach, and the condition is considered to be satisfied when the time is reached.

Fig. 2 and Fig. 3 have respectively shown the curve of welding voltage U and welding current I corresponding to two intervals of welding, and wherein, Fig. 2 is the current-voltage waveform of prior art, and Fig. 3 is the current-voltage waveform of the present utility model.

As shown in Fig. 2, during the first welding process (interval 1), the arc burns and there is no transfer of liquid metal material between the welding electrode and the workpiece. Both the welding current and the welding voltage at this time can be idealized as a constant.

With the continuous increase of the droplet, it enters the short circuit process (interval 2). Since the liquid metal forms a short-circuit bridge between the welding electrode and the workpiece. The welding voltage drops rapidly to close to 0, and the current starts to rise at the same time. During the short-circuit process, with the joint action of the electric field and the magnetic field, the weak connection at the upper end of the short-circuit bridge begins to shrink and eventually breaks. The liquid metal completes the transfer process from the welding electrode to the workpiece. So the short circuit process can also be called the process of droplet transfer. In the final stage of the short-circuit process, the metal short-circuit bridge is disconnected, and the molten droplet falls off completely, entering the third process (interval 3) where the arc is re-ignited. At the end of the short-circuit process, a sudden increase in the welding voltage and a still high welding current are simultaneously detected.

The utility model provides a device for measuring real-time welding voltage Us. Voltage sampling utilizes a waveform synchronized with the inverter trigger frequency, as shown in Figure 4. The cycle diagram of the output voltage Uinv of the inverter is denoted by T, which is divided into an inverter turn-on trigger time t1 and a stop time t2. The real-time measurement value of the welding voltage is synchronized with the synchronous pulse Syn, and two voltage values are sampled in one cycle, the instantaneous voltage value at the moment when the inverter is triggered (t1) and the welding voltage value at the moment when the inverter is stopped (t2). This process is performed by the reverse voltage source control unit 6, and this unit also stores the collected voltage values. The reverse voltage source control part 6 always collects the voltage value described above in real time. When the voltage value rises rapidly, it means that the current droplet has been shed. It also represents the end of the interval 2 short-circuit interval. By giving appropriate trigger conditions, the timing of droplet separation can be accurately determined. The second switch 4 is controlled to be closed, the first switch 3 is opened, and the reverse voltage source is connected to the current loop. In this way, the purpose of reducing the welding voltage and welding current can be achieved at the same time. By controlling the UG value of the reverse voltage source, the decreasing speed of the welding current can be controlled.

What Fig. 3 shows is the curve of the welding current and voltage after the control of the utility model. Comparing Fig. 2, it can be found that after the welding voltage rises suddenly, the welding voltage passes through the effect of the reverse voltage source UG, and when the droplet is separated, also That is, after the short circuit process is over, the values of current and voltage decrease significantly. The falling speed dI/dt of the current depends on the amplitude of UG, and the falling speed can be controlled to achieve the purpose of reducing welding spatter.

As for the timing of "triggering the connection of the reverse voltage source", it can be set by the parameter setting device 13 in FIG. 1 . The corresponding threshold or difference can be preset according to different welding current voltages and actual welding conditions. When the welding voltage reaches the threshold value, the reverse voltage source triggers the connection. It is also possible to compare two adjacent sampled voltage values when the deviation exceeds a predefined difference. The control direction voltage source is connected.

As an alternative, the connection position of the voltage sensor 11 can also be directly connected to the welding electrode 9 and the workpiece 10 at both ends. So that the sampling of the actual value of the welding voltage is as real as possible.

The above is only a preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the field of the utility model, without departing from the principle of the utility model, some improvements and modifications can also be made. And retouching should also be regarded as the protection scope of the present utility model.

Claims (10)

1. the welding machine with short circuiting arc molten drop control function comprises inversion welding source module, weldment, inverter control assembly, backward voltage source, backward voltage source control assembly, voltage sensor, current sensor, parameter setting apparatus;

Described inversion welding source module links to each other with weldment and constitutes welding circuit, described inverter control assembly links to each other with the inversion welding source module and is used to control the output of the source of welding current, can connect with weldment by the control of backward voltage source control assembly and insert welding circuit in described backward voltage source; Described voltage sensor is in parallel with weldment, is used to measure the weldingvoltage instantaneous value, and current sensor is connected with weldment, is used to measure the welding current instantaneous value; Described parameter setting apparatus links to each other with backward voltage source control assembly, is used for the setting value of given welding process electric current and voltage; Described voltage sensor, current sensor link to each other with inverter control assembly, backward voltage source control assembly respectively simultaneously, and described inversion welding source module, inverter control assembly and backward voltage source control assembly interconnect by the Syn signal synchronous.

2. the welding machine with short circuiting arc molten drop control function according to claim 1 is characterized in that: described inversion welding source module comprises the inverter that links to each other with power supply, and described inverter is the inverter of pwm pulse width modulation mode.

3. the welding machine with short circuiting arc molten drop control function according to claim 2, it is characterized in that: described weldment comprises welding electrode and workpiece; Described inversion welding source module, two ends link to each other with workpiece with welding electrode respectively and constitute welding circuit.

4. the welding machine with short circuiting arc molten drop control function according to claim 2, it is characterized in that: described inversion welding source module, be the power supply that obtains from electrical network, pwm pulse width modulated inversion circuit through three-phase commutation bridge and synchronised clock Syn synchronous working, provide input to inverter, the current/voltage that provides welding to need is provided with workpiece with welding electrode respectively at the secondary two ends of exporting behind over commutation of inverter.

5. the welding machine with short circuiting arc molten drop control function according to claim 3 is characterized in that: between described inversion welding source module and the welding electrode, be in series with smoothing reactor and circuit equivalent inductance successively.

6. the welding machine with short circuiting arc molten drop control function according to claim 3, it is characterized in that: be in series with current sensor between described workpiece and the inversion welding source module, described current sensor is leaded up to first switch and directly is connected with workpiece, and another road is connected with workpiece with second switch by the backward voltage source that is in series; Described first switch and second switch are by backward voltage source control assembly gauge tap.

7. the welding machine with short circuiting arc molten drop control function according to claim 6 is characterized in that: described first switch and second switch are IGBT or MOSFET.

8. the welding machine with short circuiting arc molten drop control function according to claim 1 is characterized in that: described voltage sensor is used for measuring the representational magnitude of voltage of weldingvoltage instantaneous value.

9. the welding machine with short circuiting arc molten drop control function according to claim 1 is characterized in that: described current sensor is used for measuring the representational current value of welding current instantaneous value.

10. the welding machine with short circuiting arc molten drop control function according to claim 1 is characterized in that: in described inverter control assembly, backward voltage source control assembly and the parameter setting apparatus microcontroller or dsp controller are installed.

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