CN102601492B - Arc-welding molten drop necking formation detection method and control method after necking formation - Google Patents

Arc-welding molten drop necking formation detection method and control method after necking formation Download PDF

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CN102601492B
CN102601492B CN201210053590.5A CN201210053590A CN102601492B CN 102601492 B CN102601492 B CN 102601492B CN 201210053590 A CN201210053590 A CN 201210053590A CN 102601492 B CN102601492 B CN 102601492B
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welding
current
necking down
molten drop
instantaneous power
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CN102601492A (en
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芦炜
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Shenzhen Megmeet Electrical Co Ltd
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Shenzhen Megmeet Electrical Co Ltd
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Abstract

The invention discloses an arc-welding molten drop necking formation detection method and a control method after necking formation. The instantaneous power of welding and the variation rate of the instantaneous power of the welding are calculated through the real-time detection for welding current and welding voltage, and the necking is formed when the variation rate of the instantaneous power is more than a certain critical value. After the necking formation, the output instantaneous power is controlled to be the some critical value, so as to control the energy when in electric exploding. The arc-welding molten drop necking formation detection method has predictability and compensates the time delay of a detection circuit, so that a welding system can perform the timely action in the aspect of control, so as to avoid the violent electric exploding; meanwhile, due to the factor of the current, the erroneous judgment caused by the over-fast rising rate of the current can be avoided.

Description

Control method after arc welding molten drop necking down generation detection method and necking down occur
[technical field]
The present invention relates to consumable electrode gas shielded welding, particularly relate to the control method after a kind of arc welding molten drop necking down generation detection method and molten drop necking down generation.
[background technology]
Gas metal-arc welding electric current, voltage and schematic diagram of droplet transfer when the droplet transfer is in short circuiting transfer state when connecing shown in Fig. 1.Wherein Ts represents the arc short circuit time, and Ta represents the electric arc arc time, and Iw represents the instantaneous value of welding current, and Vw represents the instantaneous value of weldingvoltage, and Pw represents bonding power instantaneous value, and Fig. 1 (b) represents the droplet shape in cycle droplet transfer.Be described referring to Fig. 1.
Be the short circuiting transfer period of molten drop between moment t1-t4, as shown in Fig. 1 (b), molten drop 2 is formed in the end of welding wire 1 gradually and starts to contact workpiece 4.Weldingvoltage Vw reduces rapidly in the t1 moment that short circuit starts and remains on lower value.During short circuit, first welding current Iw is controlled so as to remain unchanged, to ensure soaking between molten drop 2 and workpiece 4.After after a while, welding current Iw starts to rise gradually to form electromagnetic contractile force and Arc, promotes that molten drop necking down 2a is formed gradually, and to workpiece 4 fast transition.In the t3 moment, molten drop necking down 2b is formed gradually, until t4 moment necking down is quick-fried disconnected, molten drop 2 departs from the end of welding wire 1 completely, and electric arc 3 is formed again.
Above-mentioned necking down formation time is very short, large between tens microseconds to hundreds of microsecond, welding current Iw is because the existence of true inductance or electronic inductance, can not undergo mutation and maintain larger value, to keep larger electromagnetic push, prevent molten drop 2 transition direction under other External Force Acting from deflecting.Simultaneously because bottleneck current path cross section narrows gradually, the energy being accumulated in bottleneck increases instantaneously, until bottleneck occurs quick-fried disconnected because of overheated or gasification, this phenomenon is the one of the main reasons producing spatter phenomenon.
Prior art is formed by necking down when judging the droplet transfer, distinguishes droplet transfer process and comes back to arcing state from short-circuit condition, and switch the control mode of welding system whereby, to obtain better welding quality.Because control object when electric current is short circuiting transfer, therefore mainly through detecting voltage, existing method judges that necking down is formed.Necking down is when being formed gradually, and the cross-sectional area of current path reduces gradually, causes current path resistance to increase.Because in the very short time that necking down is formed, curent change is less, and therefore namely the increase of current path resistance shows as the increase of weldingvoltage instantaneous value Vw, until necking down fracture, electrode drop and arc space are formed again.Simply judge whether weldingvoltage instantaneous value Vw is greater than certain critical voltage value and can judges that droplet transfer process comes back to arcing state from short-circuit condition.The another kind of method judging that necking down is formed is the rate of change being calculated weldingvoltage Vw by hardware detecting circuit or microprocessor, think that necking down is formed when the rate of change of Vw is greater than a certain critical value, droplet transfer process starts to switch from short-circuit condition to arcing state.Compared with preceding method, owing to adding the differentiation element of voltage detecting, because this increasing the foresight that necking down judges, electric current can be controlled in advance to reduce the probability of splashing and occurring.
Owing to add in the measure loop of weldingvoltage Vw as filtering from welding system inside and welding system external disturbance to obtain the filter circuit of smooth waveform, thus larger time delay is inevitably introduced, therefore above-mentioned first method is used to judge that necking down is formed, when judging that weldingvoltage Vw also switches welding system control method accordingly higher than a certain critical value, necking down discharge-induced explosion also forms larger splashing.
Above-mentioned second method, by adding differentiation element, judges the rate of change of weldingvoltage Vw, the anticipation generation of necking down, compensate for the impact detecting time delay and bring, and according to this welding current is controlled, during reducing necking down, the probability of discharge-induced explosion, decreases splashing.But the method have ignored the impact of welding current Iw.In molten drop short-circuit process, in order to accelerate the progress that necking down is formed, or arc force when welding to regulate diverse location, usually needs to control different current slope, under the acting in conjunction of this current slope and short circuit equivalent resistance, obtain the rate of change of weldingvoltage Vw.As shown in Figure 2, welding current Iw undergos mutation and short circuit equivalent resistance is constant time, namely when current path cross-sectional area does not change very greatly, weldingvoltage rate of change Vw (in figure A position) still may exceed for judging the critical value that necking down is formed, thus cause erroneous judgement, affect the normal transient of molten drop.
The essence of necking down discharge-induced explosion is that energy is accumulated rapidly in necking down, forces necking down to be ruptured or gasification, cause splashing after exceeding certain value.Therefore detect and control the requirement that this energy can meet necking down judgement, and improving the proportioning of energy under short circuit and arcing state in welding process.Prior art is had no idea direct-detection and control the energy that is shorted in arcing transfer process, and erroneous judgement or welding energy therefore may be caused to distribute not good.
[summary of the invention]
The technical problem to be solved in the present invention is to provide one accurately can sentence necking down generation, the detection method occurred with the arc welding molten drop necking down reducing splashing incidence.
Another technical problem that will solve of the present invention is to provide the control method after a kind of necking down generation, because the splashing of discharge-induced explosion generation when changing to electric arc again arcing to suppress short circuiting transfer.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is, a kind of arc welding molten drop necking down generation detection method, when arc welding, by detecting welding current and weldingvoltage in real time, calculate welding instantaneous power and welding instantaneous power rate of change, when instantaneous power rate of change exceedes a certain critical value, judge that necking down occurs.
Above-described arc welding molten drop necking down generation detection method, the weldingvoltage between welding wire end and workpiece is detected by voltage detection unit, detected the welding current flowing through welding wire and workpiece by current detecting unit, voltage and current sample signal is obtained weldingvoltage sampled signal and welding current sampling signal by filter circuit filtering interference signals; Current detection signal and voltage detection signal are sent into power calculation unit and are calculated welding instantaneous power and instantaneous power rate of change, when the rate of change of instantaneous power reaches threshold value, then judge that necking down is formed
The technical scheme of the control method after a kind of molten drop necking down occurs is, after judging that necking down occurs according to above-mentioned arc welding molten drop necking down generation detection method, the instantaneous power controlling output in a certain setting value, to control energy during discharge-induced explosion.
Control method after above-described molten drop necking down occurs, judge necking down after occurring through a certain preset time, system judges that molten drop departs from welding wire completely, now bonding power setting value is increased, the preset initial value of current adjustment unit is obtained, in this, as the initial value of arcing Isobarically Control in period after the equivalent circuit resistance calculations of the bonding power setting value increased with this and the output of power calculation unit.
Control method after above-described molten drop necking down occurs, the weldingvoltage between welding wire end and workpiece is detected by voltage detection unit, detected the welding current flowing through welding wire and workpiece by current detecting unit, voltage and current sample signal is obtained weldingvoltage sampled signal and welding current sampling signal by filter circuit filtering interference signals; Current detection signal and voltage detection signal are sent into power calculation unit and are calculated welding instantaneous power and instantaneous power rate of change, when the rate of change of instantaneous power reaches threshold value, then judge that necking down is formed; Current detection signal is also admitted to current adjustment unit as current feedback amount, and voltage detection signal is also admitted to voltage-adjusting unit as voltage feedback signal; After judgement necking down occurs, the output signal of multiplexer power switched adjuster enters current adjustment unit, current adjustment unit is by adjustment dutycycle, control the high-frequency inversion unit of main circuit, instantaneous power is made to follow the trail of set-point, realize the control to instantaneous power, prevent necking down heavy explosion.
Control method after above-described molten drop necking down occurs, judge necking down after occurring through a certain preset time, bonding power setting value is increased, the setting value of current adjustment unit is obtained after the equivalent circuit resistance calculations of the set value of the power after electric current loop initial value setup unit increases and the output of power calculation unit, and the initial value using the setting value of this current adjustment unit as arcing Isobarically Control in period.
Control method after above-described molten drop necking down occurs, after the initial value described in setting, the output signal of voltage regulator is switched to current adjustment unit by multiplexer again.
Arc welding molten drop necking down generation detection method of the present invention has anticipation, compensate for the time delay of testing circuit, welding system is controlled can action in time, acutely occurs to avoid discharge-induced explosion, simultaneously because consider the factor of electric current, avoid the too fast necking down erroneous judgement caused of current-rising-rate.
[accompanying drawing explanation]
Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
Fig. 1 is prior art molten drop electric current, voltage and schematic diagram of droplet transfer when being in short circuiting transfer state.
When Fig. 2 is the sudden change of prior art welding current, weldingvoltage rate of change exceedes critical value, causes the schematic diagram that necking down is judged by accident.
Fig. 3 is the sequential chart of each signal in welding system of the present invention.
Fig. 4 is consumable electrode arc welding necking down detection and control theory diagram of the present invention.
Fig. 5 is the flow chart of arc welding molten drop necking down generation detection method of the present invention,
[detailed description of the invention]
Fig. 4 is that the present invention is about arc welding molten drop necking down detection and control theory diagram.Main circuit is controlled by DSP, and DSP comprises detecting circuit, power calculation unit, current adjustment unit, voltage-adjusting unit VR, power governor PR, state switching circuit SW, electric current loop initial value setup unit Ia_init and multiplexer Mux.
The wire-feed motor constant speed wire feed of welding machine, the weldingvoltage Vw between welding wire end and workpiece is detected by voltage detection unit Vd, the welding current Iw flowing through welding wire and workpiece is detected by current detecting unit Id, voltage and current sample signal is wherein obtained weldingvoltage sampled signal Vs and welding current sampling signal Is from after the inside and outside interfering signal of welding system by filter circuit filtering, proportional with actual signal on these signal amplitudes, and time delay to some extent in phase place.Current detection signal Is is admitted to current adjustment unit CR (electric current loop) as current feedback amount, is also admitted to power calculation unit as the parameter calculating the outputs such as bonding power simultaneously.Voltage detection signal Vs is also admitted to voltage-adjusting unit VR as voltage feedback signal, is also admitted to power calculation unit as the parameter calculating the outputs such as bonding power simultaneously.
Power calculation unit is using voltage detection signal Vs and current detection signal Is as input quantity, using instantaneous power Pc (instantaneous voltage is multiplied by transient current), instantaneous power rate of change Δ Pc/ Δ t (carrying out differential to instantaneous power), equivalent circuit resistance Rc (instantaneous voltage is divided by transient current) as output quantity, the handoff procedure being shorted to arcing is controlled.
Fig. 3 is the sequential chart of each signal in welding system.Uppermost first curve represents the change of welding current Iw, and the second curve represents the change of weldingvoltage Vw, and the 3rd curve represents the change of welding instantaneous power, and figure (b) represents droplet transfer situation.In t1 to t3 region, welding system export be in short-circuit condition, molten drop from welding wire end gradually to mother metal transition, to the t3 moment, necking down is formed gradually, and equivalent resistance increases rapidly, because there is physics inductance and electronic inductance, electric current I w maintains higher position, and instantaneous power increases rapidly.In t 4 moment, the rate of change Δ Pc/ Δ t of the instantaneous power that power calculation unit calculates reaches threshold value, state switching circuit SW judges that now necking down is formed, the input of multiplexer Mux is switched to rapidly in the output of power governor PR, the output signal of power governor PR sends into current adjustment unit CR by multiplexer Mux, current adjustment unit CR is by adjustment dutycycle, control the high-frequency inversion unit of main circuit, instantaneous power is made to follow the trail of set-point, realize the control to instantaneous power, prevent necking down heavy explosion.
After judgement necking down occurs after a certain preset time, control system judges that molten drop departs from welding wire completely, now, rapidly bonding power setting value is increased, electric current loop initial value setup unit Ia_init obtains the setting value of current adjustment unit after calculating with the equivalent circuit resistance Rc of the output of this set value of the power and power calculation unit, the initial value using the setting value of this current adjustment unit as arcing Isobarically Control in period.Because Rc can reflect the arc length information of electric arc, the situation of arc length change can be adapted to faster by the method.After setting initial value, the output signal of voltage regulator VR is switched to current adjustment unit CR by multiplexer Mux again.
The selection of power governor PR bonding power setting value can either ensure that necking down can quick-break, and the electromagnetic force of droplet transfer necessity, can not have excessive discharge-induced explosion again simultaneously.
The above embodiment of the present invention has anticipation to the judgement that molten drop necking down produces, compensate for the time delay of testing circuit, welding system is controlled can action in time, acutely occurs to avoid discharge-induced explosion, simultaneously because consider the factor of electric current, avoid the too fast necking down erroneous judgement caused of current-rising-rate.
After molten drop necking down produces, by the energy in detection and control necking down, more directly can control energy during discharge-induced explosion, reduce and only rely on control electric current, thus molten drop stress balance may be destroyed, or the probability that the necking down that can not fuse in time causes short circuit duration long.
Welding wire again arcing time, set some performance numbers stage power initial value for this reason.From the calculating of previous stage, obtain welding system equivalent resistance, the given initial value of this stage current regulator can be obtained by initial gain value and this equivalent resistance.Because equivalent resistance can reflect arc length information, therefore the method can arc length in each droplet transfer process of dynamic adjustments during arcing, improves the stability of electric arc.

Claims (7)

1. an arc welding molten drop necking down generation detection method, is characterized in that, during arc welding, by detecting welding current and weldingvoltage in real time, calculate welding instantaneous power and welding instantaneous power rate of change, when welding instantaneous power rate of change and exceeding a certain critical value, judge that necking down occurs.
2. arc welding molten drop necking down generation detection method according to claim 1, it is characterized in that, the weldingvoltage between welding wire end and workpiece is detected by voltage detection unit, detected the welding current flowing through welding wire and workpiece by current detecting unit, voltage sampling signal and current sampling signal are obtained voltage detection signal and current detection signal by filter circuit filtering interference signals; Current detection signal and voltage detection signal are sent into power calculation unit and are calculated welding instantaneous power and welding instantaneous power rate of change, when welding instantaneous power rate of change reaches critical value, then judge that necking down is formed.
3. the control method after a molten drop necking down generation, it is characterized in that, arc welding molten drop necking down generation detection method according to claim 1 judge necking down occur after, control export welding instantaneous power in a certain setting value, to control energy during discharge-induced explosion.
4. the control method after molten drop necking down generation according to claim 3, it is characterized in that, judge necking down after occurring through a certain preset time, system judges that molten drop departs from welding wire completely, now bonding power setting value is increased, the preset initial value of current adjustment unit is obtained, in this, as the initial value of arcing Isobarically Control in period after the equivalent circuit resistance calculations that the bonding power setting value increased with this and power calculation unit export.
5. the control method after molten drop necking down generation according to claim 3, it is characterized in that, the weldingvoltage between welding wire end and workpiece is detected by voltage detection unit, detected the welding current flowing through welding wire and workpiece by current detecting unit, voltage sampling signal and current sampling signal are obtained voltage detection signal and current detection signal by filter circuit filtering interference signals; Current detection signal and voltage detection signal are sent into power calculation unit and are calculated welding instantaneous power and welding instantaneous power rate of change, when welding instantaneous power rate of change reaches critical value, then judge that necking down is formed; Current detection signal is also admitted to current adjustment unit as current feedback amount, and voltage detection signal is also admitted to voltage-adjusting unit as voltage feedback signal; After judgement necking down occurs, the output signal of multiplexer power switched adjuster enters current adjustment unit, current adjustment unit is by adjustment dutycycle, control the high-frequency inversion unit of main circuit, welding instantaneous power is made to follow the trail of setting value, realize, to the control of welding instantaneous power, preventing necking down heavy explosion.
6. the control method after molten drop necking down generation according to claim 5, it is characterized in that, judge necking down after occurring through a certain preset time, bonding power setting value is increased, the preset initial value of current adjustment unit is obtained after the equivalent circuit resistance calculations that set value of the power after electric current loop initial value setup unit increases and power calculation unit export, and the initial value using the preset initial value of this current adjustment unit as arcing Isobarically Control in period.
7. the control method after molten drop necking down generation according to claim 6, it is characterized in that, after the initial value described in setting, the output signal of voltage-adjusting unit is switched to current adjustment unit by multiplexer again.
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JP5974984B2 (en) * 2013-06-07 2016-08-23 株式会社安川電機 Arc welding apparatus, arc welding system, and arc welding method
CN106513935A (en) * 2016-12-30 2017-03-22 唐山松下产业机器有限公司 Arcing state judgment method and device and electric arc welding device
CN107042350B (en) * 2017-02-22 2019-01-29 重庆理工大学 A kind of molten drop deposition detection method applied to the manufacture of electric arc three-dimensional rapid forming
CN114160925B (en) * 2021-12-07 2024-07-16 深圳市麦格米特焊接技术有限公司 Current blocking method and device, welding system and welding machine
CN114184982A (en) * 2021-12-29 2022-03-15 成都卡诺普机器人技术股份有限公司 Welding arc striking explosion detection method and system and welding method

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