A kind of AC arc welding system
Technical field
The utility model relates to a kind of interchange input arc welding system, belongs to welding equipment and automatic field.
Background technology
Low-yield input arc welding is a kind of welding method that is directed to thin plate, still is in the starting stage.Mainly contain two kinds of welding methods at present, a kind ofly be called cold metal transition welding (CMT), another kind is called the cold plasma welding, and these two kinds of welding methods all adopt the droplet transfer mode of short circuiting transfer, but its process characteristic differs widely.For first kind of form, adopt the wire feeding mode of push-and-pull silk, use custom-designed wire feed system, wire-feed motor is finished the rotating action under very high frequency, monitor short-circuit signal in welding process, feed back to wire-feed motor, wire-feed motor gives a response the pumpback welding wire, thereby welding wire is separated with molten drop, reduced the energy input.And second kind of form adopts continuous wire feeding mode forward, uses common wire feed system to cooperate the Waveform Control technology of short circuiting transfer, uses the welding wire that contains special component, reaches the effect that reduces the welding energy input.No matter yet which kind of process form, bigger deficiency is all arranged: the CMT method still adopts the dc reverse connection mode to work, though reduced energy in short-circuit stage, but because short circuit energy itself is very little, so the reduction to the input of mother metal heat is limited, only a little less than traditional surface tension transition method (STT); The cold plasma welding adopts special welding wire to be not easy to promote, and adopts the working method of dc reverse connection equally, can't effectively reduce energy.Beijing University of Technology adopted push-and-pull silk mode to realize low-yield welding in earlier stage, realized similar function in different ways with CMT, but power supply adopts the form of dc reverse connection equally, is used to heat mother metal at arcing phase heat greatly, therefore still has very big energy to reduce the space.
The utility model content
Deficiency based on existing low-yield input arc-welding method, the utility model proposes a kind of novel interchange input arc welding system, native system adopts the wire feeding mode of push-and-pull silk, and the source of welding current adopts different output polarities in the different phase of short circuit/arcing simultaneously.Short circuiting transfer is finished under the effect of welding wire pumpback pulling force, can adopt less short circuit current, and the arcing initial stage is adopted straight polarity direct current in addition, makes the energy of electric arc more distribute to welding wire, and the hot input quantity of mother metal is further reduced.
The low-yield arc welding system that the utility model proposed is made of welding power source system and wire feed system two parts.
Welding power source system comprises the control circuit part 2 that directly provides the main circuit part 1 of power output for welding and be used to regulate main circuit part 1 power output.Control circuit part 2 comprises dsp system A, an inversion driving and holding circuit B, peripheral unit control and operating part C, human-computer interaction interface D, wire feed system control interface circuit E, secondary inversion driving and holding circuit F.Wherein:
Dsp system A links to each other with part B~part F, receives electric current, the voltage signal of main circuit part, the output control signal.Once, secondary inversion driving and holding circuit B and F, receive the signal of dsp controller, isolate and amplify the break-make that rear drive once reaches secondary inversion part IGBT.Peripheral unit control and operating part C comprise arc welding gun switch C1, air valve C2.C1 all links to each other with dsp system A with C2, and C1 provides the welding switching signal to A, and the instruction that C2 receives A provides protection gas to welding process.Human-computer interaction interface D realizes the demonstration of welding parameter and presetting of welding parameter.Wire feed system control interface circuit E links to each other with wire feed system 3.
Wire feed system adopts AC servo motor to do wire-feed motor, accepts the signal that dsp system A sends by the wire feed system control interface circuit E in the control circuit part 2.
The control method of the low-yield arc welding system that the utility model proposed is as described below: in this method, wire feed system is done the reciprocal wire feed of high frequency, and the droplet transfer finishes under welding wire pumpback pulling force and electromagnetic contractile force acting in conjunction.Source of welding current controller judges that according to the weldingvoltage feedback signal welding process is in short circuit or arc stage, adopts the current value of opposed polarity in different phase.Concrete steps are as follows:
1) according to actual requirement, determine welding parameter: comprise wire feed rate V, short circuit initial stage electric current I dc, short circuit initial stage time T dc, positive polarity electric current I en, positive polarity time to peak Tap, negative polarity peak point current Ibp, negative polarity time to peak Tbp, negative polarity background current Ibb import dsp system A by human-computer interaction interface D with above welding parameter.
2) whether dsp system A detection arc welding gun switch C2 opens, and is then to start wire feed system 3 by wire feed system control interface circuit E, and dsp system A judges that by the weldingvoltage feedback signal that receives welding process is in short circuit or arc stage.
Short-circuit stage, at first wire feed system 3 control motors advance welding wire, dsp system A sends control signal behind secondary inversion driving and holding circuit F, drive secondary inversion part 1.7 and make power supply output reversed polarity, be that workpiece is an anode for the negative electrode welding wire, dsp system A makes power supply output short-circuit initial stage electric current I dc, and keeps Tdc action time through an inversion driving and inversion part 1.3 of holding circuit B control simultaneously; Then, dsp system A sends control signal, drive secondary inversion part 1.7 through part F and make the power supply output cathode, be that workpiece is a negative electrode for the anode welding wire, and providing positive polarity electric current I en by an inversion part 1.3, wire feed system 3 control motors make the welding wire pumpback, under the effect of welding wire pumpback pulling force, finish short circuiting transfer, and guarantee that electric arc ignites smoothly again.
Arc stage after the feedback voltage of dsp system A by power output part 1.8 detects the arcing signal, promptly enters arc stage, and this moment, welding wire continued to keep pumpback, and the power supply output cathode remains unchanged, and workpiece still be that the anode welding wire still is a negative electrode.After positive polarity time to peak Tap arrives, dsp system A exports control signal, drive secondary inversion part 1.7 through part F, make power supply output reversed polarity, be that workpiece is an anode for the negative electrode welding wire, dsp system A makes power supply output negative pole peak point current Ibp through inversion part 1.3 of part B control simultaneously.Behind negative polarity peak point current Ibp Tbp action time, dsp system A makes power supply output negative pole background current Ibb through inversion part 1.3 of part B control, and wire feed system 3 control motors advance welding wire.
The span of described wire feed rate V is 3~7m/min, the general value of short circuit initial stage electric current I dc is 3~100A, the short circuit initial stage, function of current time T dc was 0.5~5ms, positive polarity electric current I en value is 20~150A, positive polarity time to peak Tap value is 0~5ms, negative polarity peak point current Ibp span is span 0.1~3ms of 120~300A, negative polarity time to peak Tbp, and the span of negative polarity background current Ibb is 10~50A.
Whole welding process cooperates different multistage electric currents to form by the pumpback of advancing of welding wire, cooperates by reasonable parameter, can realize stable welding process.
Compared with prior art, the control method and the arc welding system of the utility model employing have the following advantages:
1) input of welding process energy is low, process stabilization is reliable.The utility model method cooperates AC welding power source and push-and-pull wire feed system; Short-circuit stage converting power source output polarity is easy to realize exchanging commutation, utilizes the effect of welding wire pumpback pulling force to guarantee to finish short circuiting transfer under little current status simultaneously; Arcing adopts straight polarity direct current in earlier stage, and the later stage is adopted reversal connection, promptly can the allocation proportion of reasonable distribution arc energy between welding wire and workpiece, further reduce heat input to workpiece, and realize easily that again arc length regulates, guarantee the stability of electric arc;
2) wire feed system adopts AC servo motor to do wire-feed motor, has high dynamic response performance, and the wire feed process is accurately controlled;
3) applied range: can be applied to surface overlaying, ultra-thin plate and galvanized steel plain sheet welding, prevent that effectively weldment from burning and the volatilization of zinc-plated protective layer, be with a wide range of applications.
Description of drawings
Fig. 1 welding system structure composition diagram
Fig. 2 main program software scenario figure
Fig. 3 welding procedure block diagram
Fig. 4 current waveform figure
The specific embodiment
To describe present embodiment in conjunction with the accompanying drawings now.(embodiment carries out the welding of butt weld at the thick 3A21 aluminium alloy plate of 1mm)
The low-yield input arc welding system of an instantiation structure of the present utility model is formed as shown in Figure 1, comprises two parts generally: welding system and wire feed system.
Welding system comprises main circuit part 1 and is control core circuit part 2 with TMS320F2812DSP.The main circuit input voltage is three-phase 380V; Input rectifying 1.1 adopts Fuji's rectifier bridge rectification, and model is FUJ 6RI100G-160; One time inverter circuit 1.3 adopts the semi-bridge inversion structure, and the IGBT that is BSM150GB120DN2 by two models forms; Intermediate-frequency transformer 1.4 adopts the ultracrystallite magnetic core, and transformation ratio is 15: 2; Secondary filtering 1.6 adopts magnetic core pulsactor, the about 30 μ H of inductance value; Secondary inverter circuit 1.7 adopts the semi-bridge inversion structure, and the IGBT that is BSM150GB120DN2 by two models forms.The control system that control circuit part 2 adopts based on TMS320F2812DSP is mainly finished calculation of parameter, proportional integral adjusting, SECO, and can realize communicating by letter with wire feed system 3.Below in conjunction with accompanying drawing it is elaborated.
Its job order is: after input three-phase 380V alternating current process rectifying part 1.1 rectifications and filtering 1.2 filtering, become the direct current of 540V, then through becoming the alternating current of 20KHz after inverter circuit 1.3 (this is by 2 controls of a control circuit part) inversion and the intermediate-frequency transformer 1.4 step-downs isolation, again through becoming the used big current low voltage direct current of welding after output rectifier 1.5 and secondary filtering 1.6 filtering.According to the control needs, secondary inversion part 1.7 is switched the polarity of this direct current output then, finally by bonding power output 1.8 outputs.Because the operating frequency of above circuit is 20KHz, outputting inductance also very little (about 30 μ H) is adjusted the control that inverse switch frequency or pulsewidth can reach the microsecond level simultaneously, so the type power supply reaction speed is fast, dynamic property is good.
The composition and the function of welding system control circuit part 2 are respectively:
Dsp system A mainly is made up of TMS320F2812DSP, comprises three importations.First importation is that wherein electric current is adjusted current deviation in real time via PI control (proportional plus integral control) from electric current, the magnitude of voltage of bonding power output 1.8 outputs, realizes closed-loop control; Magnitude of voltage is used to monitor welded condition.Second importation is the arc welding gun switch signal C1 that obtains from portion C.The welding parameter that the 3rd importation derives from human-computer interaction interface D presets, and obtains the welding initial parameter.Part A is mainly finished the response of welding parameters input and external signal as the core control section, and handles, calculates and change the back B, C, D, E four parts are controlled through software, makes whole welding system co-ordination, finishes predetermined welding purpose.
Wire feed system 3 adopts AC servo motor to do wire-feed motor, accepts the signal that dsp system A sends by the wire feed system control interface circuit in the control circuit part 2.
Programme-control of the present utility model divides two parts: welding wire motion (being the wire feeding motor rotary motion trace) programme-control and the programme-control of welding process dsp system are elaborated respectively below.
Welding wire motion (being the wire feeding motor rotary motion trace) programme-control:
Require to determine welding parameter according to welding is actual, according to the wire feed rate V in the welding parameter determine wire feed frequency F (advancing and the pumpback number of times of welding wire per second, last time can be regarded as once) and wire feed step-length d (each welding wire advance with pumpback apart from poor).Wire feed system control interface circuit E receives the signal of dsp system A, and the control wire feeding motor is done the pumpback campaign of advancing by predetermined step-length.
The programme-control of welding process dsp system is elaborated to this example with reference to program flow diagram:
Fig. 2 is that DSP controls low-yield inversion electric arc welding power supply main program software scenario figure.Software main program comprises: initialization subroutine, preset parameter and display subroutine, time delay subroutine, counting subroutine and welding subprogram.The concrete execution sequence of its main program is: behind the electrification reset, program brings into operation from initial address, and system carries out initialization subroutine earlier, finishes the initial value of each welding parameter and sets.Execution parameter presets subprogram then, presetting wire feed rate V is that 3.5m/min, short circuit initial stage electric current I dc are that 20A, short circuit initial stage time T dc are that 2ms, positive polarity electric current I en are that 70A, positive polarity time to peak Tap are that 1ms, negative polarity peak point current Ibp are that 80A, negative polarity time to peak Tbp are that 0.5ms, negative polarity background current Ibb are that welding parameters such as 20A are used for Control Welding Process, preset welding parameter and be used for Control Welding Process, through display subroutine relevant parameter is set demonstration then.Judge then whether the welding switch is opened, and is then to open pulsewidth modulation (promptly can export energy), starter motor, judge whether striking is successful, if striking success then enter welding procedure, up to detecting the welding end signal, close pulsewidth modulation, disable motor, withdraw from welded condition.Carry out the front program as not welding the commencing signal circulation once more of then delaying time behind the certain hour (as 20ms).Control method of the present utility model is mainly reflected in the control procedure of wire feed process and welding current waveform.
Fig. 3, Figure 4 shows that welding procedure block diagram and current waveform schematic diagram, mainly carry out state judgement, SECO and according to the different current parameters of different sequential outputs.Its process is:
At first welding wire advances and judges whether to be short-circuited according to feedback voltage.If be short-circuited, dsp system A sends control signal behind secondary inversion driving and holding circuit F, drive secondary inversion part 1.7 and make power supply output reversed polarity, be that workpiece is an anode for the negative electrode welding wire, dsp system A is through an inversion driving and inversion part 1.3 of holding circuit B control simultaneously, make power supply output short-circuit initial stage electric current I dc, and continuous action time T dc; Then, dsp system A sends control signal, drive secondary inversion part 1.7 through part F and make the power supply output cathode, be that workpiece is a negative electrode for the anode welding wire, and provide positive polarity electric current I en by an inversion part 1.3, wire feed system 3 control motors make the welding wire pumpback, under the effect of welding wire pumpback pulling force, finish short circuiting transfer.
Judging whether to take place arcing according to feedback voltage then, is then to enter arc stage, and this moment, welding wire continued to keep pumpback, and the power supply output cathode remains unchanged, and workpiece still is that the anode welding wire still is negative electrode.After positive polarity time to peak Tap arrives, dsp system A exports control signal, drive secondary inversion part 1.7 through part F, make power supply output reversed polarity, be that workpiece is an anode for the negative electrode welding wire, dsp system A makes power supply output negative pole peak point current Ibp through inversion part 1.3 of part B control simultaneously.Behind negative polarity peak point current Ibp Tbp action time, dsp system A makes power supply output negative pole background current Ibb through inversion part 1.3 of part B control, and wire feed system 3 control motors advance welding wire.
Whole process is to judge welded condition according to feedback voltage, and in conjunction with the motion conditions of welding wire, provides corresponding electric power polarity and current value, and welding parameter and welding wire motion conditions are well combined, and has realized low-yield welding.
The above is an example of native system and control method thereof, and we also can carry out some conversion to it.Can adopt full bridge inverter to replace the half-bridge form such as main circuit part, control section is realized its function with other DSP or single-chip microcomputer replacement TMS320F2812, and wire feeding motor and wire feed curve slightly adjust etc.As long as it is consistent that its system and control thought and the utility model are narrated, all should be considered as scope of the present utility model.