WO2014114035A1 - Control method of short circuiting transient process in gas metal arc welding - Google Patents

Control method of short circuiting transient process in gas metal arc welding Download PDF

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Publication number
WO2014114035A1
WO2014114035A1 PCT/CN2013/074394 CN2013074394W WO2014114035A1 WO 2014114035 A1 WO2014114035 A1 WO 2014114035A1 CN 2013074394 W CN2013074394 W CN 2013074394W WO 2014114035 A1 WO2014114035 A1 WO 2014114035A1
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Prior art keywords
welding
short circuit
short
current
conductance
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PCT/CN2013/074394
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French (fr)
Chinese (zh)
Inventor
孙子健
刘毅
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昆山华恒焊接股份有限公司
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Publication of WO2014114035A1 publication Critical patent/WO2014114035A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/095—Monitoring or automatic control of welding parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/09—Arrangements or circuits for arc welding with pulsed current or voltage
    • B23K9/091—Arrangements or circuits for arc welding with pulsed current or voltage characterised by the circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
    • B23K9/1006—Power supply
    • B23K9/1043—Power supply characterised by the electric circuit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/16—Arc welding or cutting making use of shielding gas
    • B23K9/173—Arc welding or cutting making use of shielding gas and of a consumable electrode

Definitions

  • the invention relates to a gas metal arc welding welding technology, in particular to a control method for a short circuit transition process in a fusion gas gas shielded welding which can effectively reduce splashing.
  • MIGW Gas Metal Arc Welding
  • the Lincoln Electric Company of the United States has proposed an STT (Surface Tension Transfer) welding method.
  • STT Surface Tension Transfer
  • the method for controlling the short-circuit type welding system is to take different output currents at different stages in the short-circuit transition process, especially in the final stage of the short circuit, to rapidly reduce the current, so that the droplet can rely on the surface tension to transition to The molten pool is removed to eliminate the explosion in the final stage of the short circuit, reduce the splash, and also improve the formation of the weld.
  • (C) is a waveform of variation of the welding current i and the welding voltage u in the welding process in the gas shielded welding
  • (A) is a droplet and arc burning condition corresponding to the welding current i and the welding voltage u.
  • (c) The t sc engraving indicates that the droplet has just started to contact the molten pool (corresponding to time b in (A)), and the arc is short-circuited; at this time, the contact area between the droplet and the molten pool is very small, almost a point; Under the action of tension, the contact area rapidly expands to form a liquid neck (corresponding to time c in (A); as the current rises rapidly, the electromagnetic contraction force generated by the current flowing through the liquid neck makes the liquid neck thinner ( Corresponding to the time d in (A), the liquid metal of the droplet flows more and more into the molten pool; the current is very large at time e in (A), and the liquid neck is also very thin.
  • t c in Fig. 2 indicates the timing at which the welding current i starts to switch in the short-circuit phase. Only when the current has dropped sufficiently small before the instant t sc2 at the instant of the end of the real short circuit, can it be ensured that no violent splash is produced. Studies have shown that this t c is about 100 microseconds ahead of t sc2 . When it is too late, there is no guarantee that the current will actually decrease. Too early, the droplets lack sufficient electromagnetic contraction force, cannot shrink enough, and may not even break. The wire and the molten pool are "frozen", the arc cannot be re-ignited, and it can only end with a violent explosion. Process stability is threatened.
  • An object of the present invention is to provide a control method for a short-circuit transition process in a molten gas gas-preserving welding which can be accurately controlled to effectively prevent splashing.
  • the present invention provides a control method for a short circuit transition process in a gas metal arc welding, the control method comprising rapidly conducting the conductance in the welding circuit in a short circuit phase in which the droplet is in contact with the molten pool. Constantly detecting, and adjusting the welding current energized by the short-circuit load according to the change of the conductance in the late stage of the thinning of the molten liquid neck, and adjusting the welding current to a preset base value at the end of the short circuit Current.
  • the control method further includes reducing the welding current to the aforementioned predetermined base current at a later stage of the arcing phase of the droplet formation.
  • control method further includes: from the point contact to the liquid neck stable molding between the droplet and the molten pool in the short circuiting stage, that is, the short circuit period from the start of the short circuit to the time when the growth rate of the conductance is significantly lowered, The welding current is adjusted according to the change of the conductance, and the welding current is converted into a short-circuit peak current when the conduction speed increase is significantly reduced.
  • the time interval between the conductance and the welding current for each detection and regulation is 10-200 microseconds.
  • the welding current is reduced in regulation proportional to the rate of decrease of the conductance, i.e., di/dt is proportional to dG/dt until the liquid neck is broken.
  • the welding current is increased in regulation proportional to the rate of increase of the conductance.
  • the arc voltage is continuously detected, and the welding current is adjusted according to the change of the arc voltage until the arc voltage is increased to 14-20 volts.
  • the welding current is converted into a high current of the arcing peak.
  • the invention has the beneficial effects that the invention directly and continuously detects the conductance in the welding circuit during the short circuit phase in which the droplet is in contact with the molten pool, and according to the conductance in the late stage of the short circuit in which the molten liquid neck is tapered.
  • the change of the welding current for energizing the short-circuit load is adjusted accordingly to regulate the welding current to a preset base current at the end of the short-circuit, so that the welding current can be continuously continuous according to different conditions of the molten liquid neck.
  • the detection and regulation make the control effect more accurate and effective, and thus effectively prevent the phenomenon of droplet explosion or splashing during the short circuit transition in the gas shielded welding.
  • 1 is a waveform diagram of current and voltage in a prior art welding process and a corresponding arc combustion state diagram; 2 is a schematic diagram of regulation of welding current in the prior art;
  • Figure 3 is a diagram showing the expansion of the current and voltage waveforms in the short-circuit phase of Figure 1 and the change of the conductance in the welding circuit during the short-circuit phase;
  • FIG. 4 is a schematic diagram of the comparison of the regulation of the welding current according to the change of conductance in the late stage of the short circuit of FIG. 3 with the prior art;
  • FIG. 5 is a schematic diagram showing the comparison between the regulation of the welding current according to the change of the conductance in the early stage of the short circuit of FIG. 3 and the prior art;
  • Fig. 6 is a diagram showing the current regulation waveform of the present invention.
  • FIG. 4 to FIG. 6 for corresponding control waveform diagrams of the control method for the short circuit transition process in the gas metal arc welding of the present invention.
  • the welding process of the gas metal arc welding can be understood as the repeated state of the arc phase and the short circuit phase T sc .
  • the arcing phase includes the early arcing (corresponding to the period between t sc2 and t b in Figures 2 and 6), the middle arc period (corresponding to the period between t b and t d in Figs. 2 and 6) and the arcing Late (corresponding to the period between t d and t scl in Figures 2, 5, and 6). As shown in Fig.
  • the early arcing can be understood as the trimming period after the short circuit is completed in the prior art; in this period, since the short circuit is just finished, the molten pool and the molten droplet are still unstable, and even accidental Contact; if the arc current peak current i parc is added too early, it is possible to generate a new explosion, a new splash; but the arc current peak current is too late, the wire can not melt in time, the arc is elongated The welding wire may be inserted into the molten pool, forming another short circuit, or even "frozen", and the consequences are equally unimaginable; therefore, the current should continue to maintain a low level of time after the short circuit ends.
  • a suitable arcing transition period is provided for the droplet, and the control method of the short-circuit transition process in the gas metal arc welding of the present invention is interrupted in the early stage of arcing, that is, in the liquid neck.
  • the arc voltage is continuously detected, and the welding current is adjusted according to the change of the arc voltage until the arc voltage is increased to 14-20v, and the welding current is converted.
  • the arcing peak large current i parc and enter the middle of the arc.
  • the arcing peak current i parc can promote the formation of the droplet as soon as possible, thereby reducing the subsequent welding current to small.
  • the current, the drop of the droplets and the calming of the bath provide more time, ensuring smooth and reliable contact and fusion of the droplets with the bath.
  • the arcing peak large current i parc is maintained in the middle of the arcing period (ie, between t b and t d ) to promote the droplet
  • the late arcing period ie, the period between t d and t scl
  • the droplets are basically no longer grown, which makes the droplets and the turbulent molten pool that originally tumbling on the wire head slowly calm down; at this time, due to the slow melting of the wire, the arc is shortened.
  • the short-circuit transition begins and the short-circuit phase T sc is entered.
  • (B) is the waveform of the welding voltage u after the short-circuiting phase expansion in FIG. 1(B);
  • (C) is the waveform of the welding current i after the short-circuiting phase expansion in FIG. 1(C)
  • D is the change in the loop conductance G in the welding circuit.
  • the short-circuiting phase T se can be divided into a short-circuiting period in which the liquid neck rapidly increases according to the change of the molten liquid neck (corresponding to the period between t scl and t a in FIGS. 2 and 6), and a short-circuit medium in which the liquid neck is stably increased. (corresponding to the period between ⁇ and t c in Figures 2 and 6) and the liquid neck begins to contract to the interrupted short-circuit period (corresponding to the period between t c and t sc2 in Figures 2 and 6).
  • the loop conductance G is the conductance in the welding loop, that is, the reciprocal of the resistance in the welding loop, which is equal to the welding current i shown in FIG. 3 divided by the welding voltage u.
  • the loop conductance G also varies with the change of the liquid neck during the short circuit.
  • the loop conductance G in the welding circuit is also very small.
  • the contact area is sharply enlarged, and the loop conductance G is also increasing.
  • the loop conductance G also corresponds to a larger one; at the end of the short circuit, the liquid neck becomes thinner until it finally breaks into a line and breaks, and the loop conductance G also drops rapidly, forming a basin-shaped curve like a bottom upward.
  • the G curve represents the change in conductance in the welding circuit, that is, the change in resistance in the welding circuit.
  • the welding voltage u of the welding circuit contains many components in the two ends of the voltage signal, such as wires, workpieces, contact tips, welding torches, droplets, and the like. There is no arc because it has been shorted.
  • the change in loop conductance G reflects the change in resistance of these components. However, only the resistance of the droplets changes drastically as shown in Figure 3 during the short circuit. The states of other parts are relatively constant, and there is no possibility of multiple or even dozens of changes. It can be seen that the loop conductance G curve actually reflects the change of the liquid neck state, which can also be called the change curve of the molten liquid neck conductance. If the loop conductance G itself is a combination of multiple factors, then the change dG/dt is single factor, reflecting only the change of the liquid neck state, and has a clear physical meaning.
  • the entire G curve can be roughly divided into four sections: the AB section rises sharply, and the droplet and the molten pool begin to merge, which corresponds to the pre-short period, which is very fast, and the general delay Less than 1 millisecond; BC is a stable growth segment, the liquid neck changes relatively slowly, corresponding to the short-term medium, this period of delay is the longest, usually several milliseconds; after point C, the electromagnetic contraction force begins to play a significant role, the liquid neck begins Shrinkage becomes thinner, G begins to gradually decrease until the liquid neck interruption at point E corresponds to the late stage of short circuit. The CD segment generally lasts about 1 millisecond in this period. When it reaches point D, the liquid neck has become quite thin, and G drops sharply to point E. That is, at the moment when the short circuit ends t se2 , the DE segment develops extremely fast, and the duration is about 100 microseconds.
  • FIG. 4 is a diagram showing changes in the short-circuit late-circuit conductance G and the welding current i, wherein the solid line G can be understood to mean that the liquid neck changes with time in the prior art, and the solid line i represents In the prior art, the welding current i is switched at a time corresponding to the position of the G curve D point, so that the welding current becomes small at the end of the short circuit, thereby reducing the splash.
  • the control method of the present invention mainly adopts a combination of an inverter power supply and a computer control to perform the above-mentioned welding current regulation, and sets a time interval of the detection and regulation of the loop conductance G and the welding current i to 10-200 microseconds. And the welding current is set to be controlled to decrease proportionally to the decreasing speed of the loop conductance G, that is, di/dt is proportional to dG/dt until the liquid neck is broken.
  • the conductance curve G is only about 1 millisecond from the point C which starts to decrease slightly to the last point E. time. It can be seen from Fig. 4 that after the regulation of the welding current of the present invention, the electromagnetic contraction force is lowered due to the decrease of the current, and the conductance curve G is slowed down, and the time from the C point to the E point can be significantly increased to 2-3. In milliseconds, this provides great convenience for the regulation of the welding current.
  • the G curve in Fig. 5 is the curve of the loop conductance G in the early stage of the short circuit in Fig. 3, and can also be directly understood as the curve of the liquid neck conductance.
  • the solid line i curve represents the regulation state of the welding current in the prior art of the short circuit, and the broken line i represents the control curve of the welding current according to the change of the loop conductance G in the control method of the present invention.
  • control method of the present invention is arranged to quickly and continuously detect the loop conductance G in the welding circuit in the early stage of the short circuit, as indicated by the broken line i in FIG. 5, when the loop conductance G is detected to increase, the welding is performed. The current is also adjusted accordingly.
  • the rate of increase in conductance is significantly reduced, indicating that the liquid neck has basically been stably formed, that is, into the mid-short phase, at which time the welding current is converted into a short-circuit peak current i psc .
  • This detection and regulation is carried out in rapid succession at a small time interval, as in the case of the short-circuit current regulation shown in Fig. 4 previously described.
  • the continuous monitoring and control of the G curve allows the droplet to be added to the short-circuit peak current only after it has been fused with the molten pool, thus ensuring the reliability of the short-circuit pre-regulation.
  • the control method of the present invention comprises: in the short circuit phase T sc in contact with the molten pool and in the welding loop
  • the loop conductance G performs rapid and continuous detection, and firstly adjusts the welding current according to the change of the loop conductance G in the pre-short period of the liquid neck gradually thickening (corresponding to the period between ⁇ and ⁇ ),
  • the liquid neck is stably formed to avoid being burned, splashed or "frozen"; secondly, in the middle of the short circuit in which the liquid neck grows stable (corresponding to the period between ⁇ and t c ), the short-circuit peak current i psc is maintained to provide
  • the molten liquid neck has sufficient electromagnetic contraction force; again, in the late stage of the liquid neck thinning (corresponding to the period between t c and t sc2 ), the welding current energizing the short-circuit load is correspondingly reduced according to
  • the subsequent welding current is reduced to a small current, the droplet drop is stable, and the molten pool is calmed down to provide more time, ensuring smooth and reliable contact and fusion of the droplet and the molten pool; finally, in the late arcing period (corresponding to t d to t During the period between scl , the welding current is gradually lowered to calmly enter the short-circuit phase T sc .
  • the portion of the current monitoring regulation of the present embodiment shown by the broken line in FIG. 6 is only illustrative, since the welding current is controlled for a very short time each time, and the welding current is changed very little every time, so that FIG. 6 cannot Truly expressed.
  • control method of the present invention continuously and continuously detects and regulates the welding current according to different conditions of the molten liquid neck, so that the control effect is more accurate and effective, thereby effectively preventing the short circuit transition process in the gas metal arc welding.
  • the phenomenon of the droplets exploding or splashing or being "frozen” occurs.

Abstract

A control method of a short circuiting transient process in gas metal arc welding. The control method comprises that a conductance in a welding circuit in a short circuit stage of contact of molten drops and weld craters is detected fast and continuously; in later period of the short circuit that molten drop liquid necks become thin, an energized welding current of short circuit loads is correspondingly regulated and controlled according to the changes of the electrical conductance, and when the short circuit ends, the welding current is regulated and controlled to a preset background current. Therefore the welding current is detected and regulated correspondingly and continuously according to the different conditions of the molten drop liquid necks to ensure that control effect is more accurate and more effective, and therefore during the short circuiting transient process in the consumable electrode gas shielded welding, the phenomena that the molten drops explode and splash or are frozen are effectively avoided.

Description

熔化极气体保护焊中短路过渡过程的控制方法  Control method for short circuit transition process in gas metal arc welding
本申请要求于 2013 年 1 月 25 日提交中国专利局、 申请号为 201310028268.1、发明名称为 "熔化极气体保护焊中短路过渡过程的控制方法" 的中国专利申请的优先权， 其全部内容通过引用结合在本申请中。  This application claims priority to Chinese Patent Application No. 201310028268.1, entitled "Control Method for Short-Circuit Transition Process in MIG Welding", which is filed on January 25, 2013, the entire contents of which are hereby incorporated by reference. Combined in this application.
技术领域 Technical field
本发明涉及熔化极气体保护焊接技术，尤其涉及一种可有效减少飞溅的熔 化极气体保护焊中短路过渡过程的控制方法。  The invention relates to a gas metal arc welding welding technology, in particular to a control method for a short circuit transition process in a fusion gas gas shielded welding which can effectively reduce splashing.
背景技术 Background technique
熔化极气体保护焊接， 筒称 GMAW ( Gas Metal Arc Welding ), 是焊接技 术应用最广泛的一种焊接工艺，其中短路过渡是该种焊接工艺的基本技术内容 之一。但是在短路过渡过程中，尤其是在二氧化碳焊接中，往往伴随着飞溅大、 成形差的缺点。  MIGW (Gas Metal Arc Welding) is one of the most widely used welding processes in welding technology. Short-circuit transition is one of the basic technical contents of this welding process. However, in the short circuit transition process, especially in carbon dioxide welding, it is often accompanied by the disadvantages of large splash and poor forming.
为解决上述问题， 美国林肯电学公司提出了一种 STT ( Surface Tension Transfer, 表面张力传递）焊接方法， 具体可参阅于 1990年 1月 17 日公告的 中国专利第 CN 1006450B号揭露的控制短路型焊接***的方法和装置。 该种 控制短路型焊接***的方法， 筒单地说， 就是对短路过渡过程中不同阶段采取 不同的输出电流， 尤其是在短路的最后阶段， 迅速降低电流， 使熔滴能够依靠 表面张力过渡到熔池中去， 从而消除短路最后阶段的***， 减少飞溅， 同时也 改进焊缝的成形。  In order to solve the above problems, the Lincoln Electric Company of the United States has proposed an STT (Surface Tension Transfer) welding method. For details, refer to the control of short circuit type welding disclosed in Chinese Patent No. CN 1006450B published on January 17, 1990. Systematic methods and apparatus. The method for controlling the short-circuit type welding system is to take different output currents at different stages in the short-circuit transition process, especially in the final stage of the short circuit, to rapidly reduce the current, so that the droplet can rely on the surface tension to transition to The molten pool is removed to eliminate the explosion in the final stage of the short circuit, reduce the splash, and also improve the formation of the weld.
现有技术中防飞溅的方法可归纳为图 1及图 2所示。 其中图 1中 （B )和 The anti-splash method in the prior art can be summarized as shown in Figs. 1 and 2. Where in Figure 1 (B) and
( C ) 为气体保护焊中通常情况下焊接过程中焊接电流 i和焊接电压 u的变化 波形， （A )为与焊接电流 i和焊接电压 u相对应的熔滴和电弧燃烧情况。 （C ) 中 tsc †刻表示熔滴刚开始接触熔池（对应 （A ) 中时刻 b ), 电弧被短路； 这 时熔滴和熔池的接触面积非常小， 几乎是一个点； 在表面张力的作用下， 接触 面积迅速扩大， 形成了一个液颈（对应（A )中时刻 c ); 随着电流的迅速升高， 流过液颈的电流产生的电磁收缩力使液颈变细（对应（A )中时刻 d ), 熔滴的 液态金属越来越多地流到熔池中去； 到 ( A ) 中时刻 e时电流已非常大， 液颈 也非常细了。 在强大的电磁收缩力和加热的共同作用下， 液颈在（A ) 中时刻 f猛烈***断开， 电弧重新引燃， 短路过程结束， 对应 （C ) 中 tsc2。 短路过程 一共持续了如图上所示的 Tsc时间。 电弧重新引燃后， 焊丝熔化， 逐渐形成熔 滴（对应（ A )中时刻 g ); 以后熔滴不断长大（对应（ A )中时刻 h及时刻 a ), 直到又碰到熔池（对应（A ) 中时刻 b ), 重新短路， 电弧熄灭。 从短路结束时 刻 tsc2到重新短路的短路开始时刻 tscl,电弧一共燃烧了如图上所示的 Tarc时间。 Tsc加上 为一个熔滴的短路过渡周期 T。一般情况下该短路过渡周期 Τ多为 数十毫秒。试验研究表明，短路过渡过程中发生的飞溅绝大部分都发生在短路 开始时刻和短路结束时刻， 即 tscl和 tsc2两个瞬间， 即所谓危险时刻阶段。 图 2 是现有技术中对应采取措施的示意性概括，主要为使电流在这两个时刻的前后 一段时间里保持在较低的水平以防止飞溅。 (C) is a waveform of variation of the welding current i and the welding voltage u in the welding process in the gas shielded welding, and (A) is a droplet and arc burning condition corresponding to the welding current i and the welding voltage u. (c) The t sc engraving indicates that the droplet has just started to contact the molten pool (corresponding to time b in (A)), and the arc is short-circuited; at this time, the contact area between the droplet and the molten pool is very small, almost a point; Under the action of tension, the contact area rapidly expands to form a liquid neck (corresponding to time c in (A); as the current rises rapidly, the electromagnetic contraction force generated by the current flowing through the liquid neck makes the liquid neck thinner ( Corresponding to the time d in (A), the liquid metal of the droplet flows more and more into the molten pool; the current is very large at time e in (A), and the liquid neck is also very thin. Under the combined action of strong electromagnetic contraction force and heating, the liquid neck violently breaks at time f in (A), the arc reignites, and the short circuit process ends, corresponding to (c) t sc2 . Short circuit A total of the T sc time shown in the figure continues. After the arc is re-ignited, the welding wire melts and gradually forms a droplet (corresponding to (g) time g); after that, the droplet continues to grow (corresponding to time (h) and time a), until it hits the molten pool again (corresponding to (A) Medium time b), re-short circuit, arc extinguished. From the short-circuit end time t sc2 to the short-circuit start time t scl of the re-short circuit, the arc burns a total of T arc times as shown in the figure. T sc is added to the short circuit transition period T of a droplet. In general, the short circuit transition period is tens of milliseconds. Experimental studies have shown that most of the spatter that occurs during the short-circuit transition occurs at the start of the short circuit and the end of the short circuit, that is, two moments t scl and t sc2 , the so-called dangerous moment phase. Figure 2 is a schematic summary of the corresponding measures taken in the prior art, mainly to keep the current at a lower level for a period of time before and after the two moments to prevent splashing.
但是上述方法也带来很大的困难，例如图 2中 tc表示短路阶段中焊接电流 i开始切换降低时刻。只有当电流在真正短路结束的瞬间 tsc2时刻前已降到足够 小， 才能保证不产生猛烈的飞溅。 研究表明， 这个 tc领先于 tsc2的时间大约是 100微秒左右。 太晚时， 保证不了电流的确实降低。 太早了， 熔滴缺乏足够的 电磁收缩力， 不能收缩得足够细， 最后甚至可能断不开。焊丝和熔池会被"冻" 住， 电弧不能重复引燃， 最后只能以猛烈***而结束。 过程稳定性受到猛烈的 破坏。 而这种破坏的恢复往往需要好几个周期。 再加上在实际生产中， 由于焊 接电流流过的导线较长， 周围铁磁体较多， 回路中因此存在着较大的电抗， 电 流也就不能迅速切换下来。 并且生产实践表明，短路结束前大电流的极快切换 是 4艮困难的， 有时甚至于是做不到的。 However, the above method also brings great difficulties. For example, t c in Fig. 2 indicates the timing at which the welding current i starts to switch in the short-circuit phase. Only when the current has dropped sufficiently small before the instant t sc2 at the instant of the end of the real short circuit, can it be ensured that no violent splash is produced. Studies have shown that this t c is about 100 microseconds ahead of t sc2 . When it is too late, there is no guarantee that the current will actually decrease. Too early, the droplets lack sufficient electromagnetic contraction force, cannot shrink enough, and may not even break. The wire and the molten pool are "frozen", the arc cannot be re-ignited, and it can only end with a violent explosion. Process stability is devastated. The recovery of such damage often takes several cycles. In addition, in actual production, since the wire through which the welding current flows is long and there are many ferromagnetic bodies around, there is a large reactance in the circuit, and the current cannot be quickly switched. And production practice shows that the extremely fast switching of large currents before the end of the short circuit is difficult, and sometimes it can't be done.
因此，有必要提供一种改进的熔化极气体保护焊中短路过渡过程的控制方 法以解决上述问题。  Therefore, it is necessary to provide an improved control method for the short-circuit transition process in the gas metal arc welding to solve the above problems.
发明内容 Summary of the invention
本发明的目的在于提供一种可精确控制以有效防止飞溅的熔化极气体保 护焊中短路过渡过程的控制方法。  SUMMARY OF THE INVENTION An object of the present invention is to provide a control method for a short-circuit transition process in a molten gas gas-preserving welding which can be accurately controlled to effectively prevent splashing.
为实现上述发明目的，本发明提供了一种熔化极气体保护焊中短路过渡过 程的控制方法，所述控制方法包括在熔滴与熔池接触的短路阶段中对焊接回路 中的电导进行快速连续不断的检测，并在熔滴液颈逐渐变细的短路后期根据所 述电导的变化对短路负载通电的焊接电流作出相应的调控，并在短路结束时将 焊接电流调控至预先设定的基值电流。 作为本发明的进一步改进，所述控制方法还包括在熔滴形成的燃弧阶段后 期， 将焊接电流降低至前述预先设定的基值电流。 In order to achieve the above object, the present invention provides a control method for a short circuit transition process in a gas metal arc welding, the control method comprising rapidly conducting the conductance in the welding circuit in a short circuit phase in which the droplet is in contact with the molten pool. Constantly detecting, and adjusting the welding current energized by the short-circuit load according to the change of the conductance in the late stage of the thinning of the molten liquid neck, and adjusting the welding current to a preset base value at the end of the short circuit Current. As a further improvement of the present invention, the control method further includes reducing the welding current to the aforementioned predetermined base current at a later stage of the arcing phase of the droplet formation.
作为本发明的进一步改进，所述控制方法还包括在短路阶段中熔滴与熔池 之间自点接触至液颈稳定成型，即短路开始时至所述电导增速明显降低时的短 路前期，对焊接电流根据所述电导的变化作出相应的调控， 并在所述电导增速 明显降低时将焊接电流转换为短路峰值大电流。  As a further improvement of the present invention, the control method further includes: from the point contact to the liquid neck stable molding between the droplet and the molten pool in the short circuiting stage, that is, the short circuit period from the start of the short circuit to the time when the growth rate of the conductance is significantly lowered, The welding current is adjusted according to the change of the conductance, and the welding current is converted into a short-circuit peak current when the conduction speed increase is significantly reduced.
作为本发明的进一步改进，所述电导和焊接电流每次检测和调控的时间间 隔为 10-200微秒。  As a further improvement of the present invention, the time interval between the conductance and the welding current for each detection and regulation is 10-200 microseconds.
作为本发明的进一步改进，在所述短路后期， 所述焊接电流以正比于所述 电导的降低速度进行降低调控， 即 di/dt正比于 dG/dt, 直到液颈断开。  As a further improvement of the present invention, in the latter stage of the short circuit, the welding current is reduced in regulation proportional to the rate of decrease of the conductance, i.e., di/dt is proportional to dG/dt until the liquid neck is broken.
作为本发明的进一步改进，在所述短路前期， 所述焊接电流以正比于所述 电导的增加速度进行增加调控。  As a further improvement of the present invention, in the pre-short circuit period, the welding current is increased in regulation proportional to the rate of increase of the conductance.
作为本发明的进一步改进， 在所述液颈中断、 短路结束后， 对电弧电压进 行连续不断的检测， 并根据电弧电压的变化对焊接电流作出相应的调控， 直至 电弧电压增加至 14-20v后将焊接电流转换为燃弧峰值大电流。  As a further improvement of the present invention, after the liquid neck is interrupted and the short circuit is completed, the arc voltage is continuously detected, and the welding current is adjusted according to the change of the arc voltage until the arc voltage is increased to 14-20 volts. The welding current is converted into a high current of the arcing peak.
本发明的有益效果是：本发明通过在熔滴与熔池接触的短路阶段中对焊接 回路中的电导进行快速连续不断的检测，并在熔滴液颈逐渐变细的短路后期根 据所述电导的变化对短路负载通电的焊接电流作出相应的调控，以在短路结束 时将焊接电流调控至预先设定的基值电流，从而可根据熔滴液颈不同的情况对 焊接电流作出相应的连续不断的检测及调控，使控制效果更加精确有效， 进而 有效防止熔化极气体保护焊中短路过渡过程中的熔滴***飞溅或被 "冻"住的 现象的发生。  The invention has the beneficial effects that the invention directly and continuously detects the conductance in the welding circuit during the short circuit phase in which the droplet is in contact with the molten pool, and according to the conductance in the late stage of the short circuit in which the molten liquid neck is tapered. The change of the welding current for energizing the short-circuit load is adjusted accordingly to regulate the welding current to a preset base current at the end of the short-circuit, so that the welding current can be continuously continuous according to different conditions of the molten liquid neck. The detection and regulation make the control effect more accurate and effective, and thus effectively prevent the phenomenon of droplet explosion or splashing during the short circuit transition in the gas shielded welding.
附图说明 DRAWINGS
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施 例或现有技术描述中所需要使用的附图作筒单地介绍，显而易见地， 下面描述 中的附图仅仅是本发明的一些实施例， 对于本领域普通技术人员来讲，在不付 出创造性劳动的前提下， 还可以根据这些附图获得其他的附图。  In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description It is merely some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without any creative work.
图 1 是现有技术焊接过程中电流、 电压的波形图及相应的电弧燃烧状况 图； 图 2是现有技术中焊接电流的调控示意图； 1 is a waveform diagram of current and voltage in a prior art welding process and a corresponding arc combustion state diagram; 2 is a schematic diagram of regulation of welding current in the prior art;
图 3是图 1中短路阶段电流及电压波形图的扩展及短路阶段焊接回路中电 导的变化图；  Figure 3 is a diagram showing the expansion of the current and voltage waveforms in the short-circuit phase of Figure 1 and the change of the conductance in the welding circuit during the short-circuit phase;
图 4是本发明根据图 3中短路后期的电导变化对焊接电流的调控与现有技 术的调控比对示意图；  4 is a schematic diagram of the comparison of the regulation of the welding current according to the change of conductance in the late stage of the short circuit of FIG. 3 with the prior art; FIG.
图 5是本发明根据图 3中短路前期的电导变化对焊接电流的调控与现有技 术的调控比对示意图；  FIG. 5 is a schematic diagram showing the comparison between the regulation of the welding current according to the change of the conductance in the early stage of the short circuit of FIG. 3 and the prior art; FIG.
图 6是本发明的电流调控波形图。  Fig. 6 is a diagram showing the current regulation waveform of the present invention.
其中， 附图标记筒要说明如下：  Among them, the reference numeral is to be described as follows:
U-焊接电压， i-焊接电流， tscl -短路开始时刻， tsc2-短路结束时刻， Tsc-短路 阶段， Tarc -燃弧阶段， T-短路过渡周期， iparc -燃弧峰值大电流， ipsc-短路峰值大 电流， ib-基值电流， G-回路电导， ta-短路阶段中焊接电流 i开始转换成 ipsJ† 刻， 燃弧阶段中焊接电流 i开始转换成 iparc时刻， tc-短路阶段中焊接电流 i 开始切换降低时刻， td-燃弧阶段中焊接电流 i开始切换降低时刻。 U-welding voltage, i-welding current, t scl - short-circuit start time, t sc2 - short-circuit end time, T sc - short-circuit phase, T arc - arcing phase, T-short transition period, i parc - large arcing peak Current, i psc - short circuit peak current, i b - base current, G-loop conductance, t a - the welding current i in the short circuit phase begins to convert into i ps J†, the welding current i begins to convert into i parc time, t c - the welding current i starts to switch at the time of the short-circuit phase, and the welding current i starts to switch to the lowering time in the t d - arcing phase.
具体实施方式 detailed description
以下将结合附图所示的各实施方式对本发明进行详细描述。但这些实施方 式并不限制本发明， 本领域的普通技术人员根据这些实施方式所做出的结构、 方法、 算法或功能上的变换均包含在本发明的保护范围内。  The present invention will be described in detail below in conjunction with the embodiments shown in the drawings. However, the embodiments are not intended to limit the invention, and the structures, methods, algorithms, or functional changes made by those skilled in the art in accordance with the embodiments are included in the scope of the present invention.
请参阅图 4至图 6所示为本发明熔化极气体保护焊中短路过渡过程的控制 方法的对应调控波形图。 参照图 1、 图 2及图 6所示， 熔化极气体保护焊的焊 接过程可理解为燃弧阶段 和短路阶段 Tsc的重复状态。 Please refer to FIG. 4 to FIG. 6 for corresponding control waveform diagrams of the control method for the short circuit transition process in the gas metal arc welding of the present invention. Referring to Figures 1, 2 and 6, the welding process of the gas metal arc welding can be understood as the repeated state of the arc phase and the short circuit phase T sc .
其中燃弧阶段 又包括燃弧早期（对应图 2、 6中的 tsc2至 tb之间时段）、 燃弧中期（对应图 2、 6中的 tb至 td之间时段）及燃弧后期（对应图 2、 5、 6 中的 td至 tscl之间时段）。结合图 2所示，燃弧早期可理解为现有技术中短路结 束后的修整期； 在该时期中， 因为短路刚结束时， 熔池和熔滴都还很不稳定， 甚至还会发生偶然的接触； 要是把燃弧峰值大电流 iparc加得太早， 就有可能产 生新的***， 新的飞溅； 但是燃弧峰值大电流要是加得太晚， 焊丝不能及时熔 化， 使电弧拉长， 焊丝就有可能***熔池中去， 形成又一次短路， 甚至 "冻" 住， 后果同样不堪设想； 因此在短路结束后电流要继续维持一段低水平时间， 直到 tb瞬间， 才能开始转换成燃弧峰值大电流 iparc, 即进入燃弧中期。 结合图 2所示， 现有技术中往往任意地设定 tb延迟为 1毫秒， 但是该种任意设定的时 间在溶池振荡比较猛烈的情况下往往行不通， [艮难保证某一个时间长度是最合 适的， 如若时间设置不合适则会出现如上所述的新的***飞溅或 "冻"住的现 象。 结合图 6所示， 为解决该种问题， 给熔滴提供一个合适的燃弧过渡期， 本 发明熔化极气体保护焊中短路过渡过程的控制方法在燃弧早期、即在所述液颈 中断、 短路结束后的 tsc2至 tb之间时段， 对电弧电压进行连续不断的检测， 并 根据电弧电压的变化对焊接电流作出相应的调控，直至电弧电压增加至 14-20v 后将焊接电流转换为燃弧峰值大电流 iparc并进入燃弧中期。 其中当电弧电压增 加至 14-20v后即可说明电弧再被偶然短路的可能性已被消除， 此时燃弧峰值 大电流 iparc可促进熔滴的尽快形成， 从而为后续焊接电流降低为小电流、 熔滴 下坠稳定和熔池平静下来提供更多时间，保证熔滴与熔池顺利可靠地接触并融 合。 The arcing phase includes the early arcing (corresponding to the period between t sc2 and t b in Figures 2 and 6), the middle arc period (corresponding to the period between t b and t d in Figs. 2 and 6) and the arcing Late (corresponding to the period between t d and t scl in Figures 2, 5, and 6). As shown in Fig. 2, the early arcing can be understood as the trimming period after the short circuit is completed in the prior art; in this period, since the short circuit is just finished, the molten pool and the molten droplet are still unstable, and even accidental Contact; if the arc current peak current i parc is added too early, it is possible to generate a new explosion, a new splash; but the arc current peak current is too late, the wire can not melt in time, the arc is elongated The welding wire may be inserted into the molten pool, forming another short circuit, or even "frozen", and the consequences are equally unimaginable; therefore, the current should continue to maintain a low level of time after the short circuit ends. It is not until t b instant that the conversion to the arcing peak current i parc can be started, that is, into the middle of the arc. As shown in FIG. 2, in the prior art, the t b delay is arbitrarily set to 1 millisecond, but such an arbitrarily set time often fails in the case where the pool oscillation is relatively violent, [it is difficult to guarantee a certain time. The length is most suitable, and if the time setting is not appropriate, a new explosion splash or "frozen" phenomenon as described above may occur. In combination with FIG. 6, in order to solve the problem, a suitable arcing transition period is provided for the droplet, and the control method of the short-circuit transition process in the gas metal arc welding of the present invention is interrupted in the early stage of arcing, that is, in the liquid neck. During the period between t sc2 and t b after the short circuit is completed, the arc voltage is continuously detected, and the welding current is adjusted according to the change of the arc voltage until the arc voltage is increased to 14-20v, and the welding current is converted. For the arcing peak large current i parc and enter the middle of the arc. When the arc voltage is increased to 14-20v, the possibility that the arc is accidentally short-circuited can be eliminated. At this time, the arcing peak current i parc can promote the formation of the droplet as soon as possible, thereby reducing the subsequent welding current to small. The current, the drop of the droplets and the calming of the bath provide more time, ensuring smooth and reliable contact and fusion of the droplets with the bath.
另外， 结合图 6所示， 本发明熔化极气体保护焊中短路过渡过程的控制方 法中在燃弧中期（即 tb至 td之间时段）保持燃弧峰值大电流 iparc以促进熔滴的 较快形成， 直到时间到达 td时进入燃弧后期（即 td至 tscl之间时段）， 将焊接电 流逐渐降低至预先设定的基值电流 ib,使焊接电流保持在仅足以勉强维持电弧 稳定燃烧的水平，熔滴基本上不再长大， 进而使得原先在焊丝头上翻腾的熔滴 和汹涌动荡的熔池都慢慢平静下来； 此时由于焊丝熔化减慢， 电弧缩短， 直至 最后熔滴接触熔池， 开始短路过渡而步入短路阶段 Tsc。 In addition, as shown in FIG. 6, in the control method of the short-circuit transition process in the gas metal arc welding of the present invention, the arcing peak large current i parc is maintained in the middle of the arcing period (ie, between t b and t d ) to promote the droplet The faster formation, until the time reaches t d , enters the late arcing period (ie, the period between t d and t scl ), gradually reduces the welding current to the preset base current i b , so that the welding current is kept at only enough Reluctant to maintain the level of stable arc combustion, the droplets are basically no longer grown, which makes the droplets and the turbulent molten pool that originally tumbling on the wire head slowly calm down; at this time, due to the slow melting of the wire, the arc is shortened. Until the last droplet contacts the molten pool, the short-circuit transition begins and the short-circuit phase T sc is entered.
结合图 3所示， 该图中 （B )是图 1 ( B ) 中短路阶段扩展后的焊接电压 u 的波形； （C )是图 1 ( C ) 中短路阶段扩展后的焊接电流 i的波形； （D )是焊 接回路中回路电导 G的变化情况。  Referring to FIG. 3, (B) is the waveform of the welding voltage u after the short-circuiting phase expansion in FIG. 1(B); (C) is the waveform of the welding current i after the short-circuiting phase expansion in FIG. 1(C) (D) is the change in the loop conductance G in the welding circuit.
所述短路阶段 Tse根据熔滴液颈的变化可分为液颈快速增大的短路前期 (对应图 2、 6中的 tscl至 ta之间时段）、 液颈稳定增大的短路中期（对应图 2、 6中的 ^至 tc之间时段）及液颈开始收缩至中断的短路后期（对应图 2、 6中 的 tc至 tsc2之间时段）。 其中回路电导 G为焊接回路中的电导， 即为焊接回路 中电阻的倒数， 等于图 3所示焊接电流 i除以焊接电压 u。 结合图 1及图 3可 以看出在短路期间回路电导 G随着液颈的变化也是变化的。 在短路前期， 因 为熔滴与熔池接触面积极小， 焊接回路中的回路电导 G也相应非常小， 随着 熔滴与熔池的融合， 接触面积急剧扩大， 回路电导 G也不断增加； 在短路中 期， 液颈增长到最大， 回路电导 G也对应较大； 在短路后期， 液颈不断变细， 直到最后细成一根线而断裂， 回路电导 G也急速下降， 形成类似一个底朝上 的盆型曲线。 该 G 曲线即代表着焊接回路中电导的变化情况， 亦即焊接回路 中电阻的变化情况。焊接回路的焊接电压 u包含着取电压信号的两端内的许多 组成部分， 如导线、 工件、 导电嘴、 焊枪、 熔滴等等。 因为已经短路了所以没 有电弧。 回路电导 G的变化反映这些组成部分的电阻在变化。 但是只有熔滴 的电阻在短路过程中发生如图 3所示的猛烈变化，其他部分的状态相对都是比 较恒定的， 不可能有成倍乃至几十倍的变化。 由此可见回路电导 G 曲线实际 上反映了液颈状态的变化，也可称为熔滴液颈电导的变化曲线。假如说回路电 导 G本身是多因素的组合， 那么其变化 dG/dt却是单因素的， 只反映液颈状态 的变化， 有明确的物理意义。 The short-circuiting phase T se can be divided into a short-circuiting period in which the liquid neck rapidly increases according to the change of the molten liquid neck (corresponding to the period between t scl and t a in FIGS. 2 and 6), and a short-circuit medium in which the liquid neck is stably increased. (corresponding to the period between ^ and t c in Figures 2 and 6) and the liquid neck begins to contract to the interrupted short-circuit period (corresponding to the period between t c and t sc2 in Figures 2 and 6). The loop conductance G is the conductance in the welding loop, that is, the reciprocal of the resistance in the welding loop, which is equal to the welding current i shown in FIG. 3 divided by the welding voltage u. It can be seen in conjunction with Figures 1 and 3 that the loop conductance G also varies with the change of the liquid neck during the short circuit. In the early stage of short circuit, For the contact surface of the droplet and the molten pool, the loop conductance G in the welding circuit is also very small. With the fusion of the droplet and the molten pool, the contact area is sharply enlarged, and the loop conductance G is also increasing. When the neck grows to the maximum, the loop conductance G also corresponds to a larger one; at the end of the short circuit, the liquid neck becomes thinner until it finally breaks into a line and breaks, and the loop conductance G also drops rapidly, forming a basin-shaped curve like a bottom upward. The G curve represents the change in conductance in the welding circuit, that is, the change in resistance in the welding circuit. The welding voltage u of the welding circuit contains many components in the two ends of the voltage signal, such as wires, workpieces, contact tips, welding torches, droplets, and the like. There is no arc because it has been shorted. The change in loop conductance G reflects the change in resistance of these components. However, only the resistance of the droplets changes drastically as shown in Figure 3 during the short circuit. The states of other parts are relatively constant, and there is no possibility of multiple or even dozens of changes. It can be seen that the loop conductance G curve actually reflects the change of the liquid neck state, which can also be called the change curve of the molten liquid neck conductance. If the loop conductance G itself is a combination of multiple factors, then the change dG/dt is single factor, reflecting only the change of the liquid neck state, and has a clear physical meaning.
从图 3 ( C )可看到整个 G曲线大致可以分为四个区间： AB段急剧上升， 是熔滴和熔池开始融合段， 对应为短路前期， 该时期进行得非常快， 一般延时 小于 1毫秒； BC为稳定增长段， 液颈变化相对较緩慢， 对应为短路中期， 这 一段延时最长， 一般为若干毫秒； 经过 C点后， 电磁收缩力开始明显发挥作 用，液颈开始收缩变细， G开始逐步下降，直至 E点液颈中断对应为短路后期， 该时期 CD段一般历时 1毫秒左右， 到达 D点， 液颈已变得相当细， G急剧下 降， 到 E点， 也就是短路结束 tse2的时刻， DE段发展极快， 历时大约是 100 微秒左右。 It can be seen from Fig. 3 (C) that the entire G curve can be roughly divided into four sections: the AB section rises sharply, and the droplet and the molten pool begin to merge, which corresponds to the pre-short period, which is very fast, and the general delay Less than 1 millisecond; BC is a stable growth segment, the liquid neck changes relatively slowly, corresponding to the short-term medium, this period of delay is the longest, usually several milliseconds; after point C, the electromagnetic contraction force begins to play a significant role, the liquid neck begins Shrinkage becomes thinner, G begins to gradually decrease until the liquid neck interruption at point E corresponds to the late stage of short circuit. The CD segment generally lasts about 1 millisecond in this period. When it reaches point D, the liquid neck has become quite thin, and G drops sharply to point E. That is, at the moment when the short circuit ends t se2 , the DE segment develops extremely fast, and the duration is about 100 microseconds.
结合图 3及图 4所示可知，图 4为短路后期回路电导 G和焊接电流 i的变 化图， 其中实线 G可理解为表示液颈在现有技术中随时间的变化， 实线 i表示 现有技术中将焊接电流 i在 G曲线 D点位置对应时刻进行切换， 使到达短路 结束时焊接电流变得很小，从而减小飞溅。 图 4中虚线表示本发明控制方法中 的焊接电流切换方法及对应的回路电导 G的变化状态， 即在短路后期， 快速 连续不断地检测回路电导 G的变化， 当发现回路电导 G开始出现一点轻微下 降的趋势的 C点， 对应图 4中时间 t轴的 tc。时刻， 就开始把焊接电流从原来 的 ic。作相应的减少， 转换为 icl; 经过一个短暂的时段， 到 tcl时刻， 发现电导 也已从原来的 Gc。又降低了一点点， 成为 Gcl; 再对应减少焊接电流到 ic2; 再 经过同一个短暂的时段到 tc2时刻， 再次检测回路电导 G的变化， 发现回路电 导 G又降低成为 Gc2; 再对应降低焊接电流到 ic3。 以此类推下去， 经过许多次 的调控， 最后在图上 tcn时刻， 将焊接电流 icn调控降至预先设定的基值电流 ib 时， 此时可为调控降至接近或等于预先设定的基值电流 ib, 液颈也在 tsc2时刻 平静地破坏。其中本发明控制方法主要采用逆变电源与计算机控制相结合的方 式进行上述焊接电流的调控，将所述回路电导 G和焊接电流 i每次检测和调控 的时间间隔设置为 10-200微秒， 并且将焊接电流设置为以正比于回路电导 G 的降低速度进行调控降低， 即 di/dt正比于 dG/dt, 直到液颈断开。 3 and FIG. 4, FIG. 4 is a diagram showing changes in the short-circuit late-circuit conductance G and the welding current i, wherein the solid line G can be understood to mean that the liquid neck changes with time in the prior art, and the solid line i represents In the prior art, the welding current i is switched at a time corresponding to the position of the G curve D point, so that the welding current becomes small at the end of the short circuit, thereby reducing the splash. The dotted line in Fig. 4 indicates the welding current switching method and the corresponding loop conductance G in the control method of the present invention, that is, the change of the loop conductance G is detected continuously and continuously in the late stage of the short circuit, and when the loop conductance G is found to start slightly The point C of the downward trend corresponds to t c of the time t-axis in Fig. 4. At the moment, the welding current is started from the original i c . Correspondingly reduced, converted to i cl ; After a short period of time, to t cl , the conductance is found Also has been from the original G c . It is reduced a little bit and becomes G cl ; and then reduces the welding current to i c2 ; and after the same short period of time to t c2 , the change of the loop conductance G is detected again, and it is found that the loop conductance G is lowered to become G c2 ; Corresponding to reducing the welding current to i c3 . Pushing it down like this, after many times of regulation, finally, when the welding current i cn is regulated to the preset base current i b at the time t cn on the graph, the regulation can be reduced to close to or equal to the preset. The set base current i b , the liquid neck is also quietly destroyed at time t sc2 . The control method of the present invention mainly adopts a combination of an inverter power supply and a computer control to perform the above-mentioned welding current regulation, and sets a time interval of the detection and regulation of the loop conductance G and the welding current i to 10-200 microseconds. And the welding current is set to be controlled to decrease proportionally to the decreasing speed of the loop conductance G, that is, di/dt is proportional to dG/dt until the liquid neck is broken.
现有技术中由于所采用的电流波形往往是锯齿形的，越到后面，电流越大， 收缩越快， 所以电导曲线 G从开始有一点下降的 C点到最后的 E点往往只有 1毫秒左右的时间。 从图 4中可以看出经过本发明的焊接电流的调控后， 由于 电流的减少， 电磁收缩力降低， 电导曲线 G下降变慢了， C点到 E点这段时 间可显著增加到 2-3毫秒， 这对焊接电流的调控提供很大的方便。 另外， 即使 在短路后期液颈不是有规律地进行不断收缩， 回路电导 G也对应不是有规律 地进行下降， 通过本发明控制方法中对回路电导 G的不间断检测及焊接电流 i 的不间断对应调控， 即当回路电导 G下降时， 焊接电流下降； 当回路电导 G 停止变化， 焊接电流也可以停止变化； 当回路电导 G 突然出现增加时， 焊接 电流也可以相应地暂时增加一下，从而可有效保证提供给液颈足够的电磁收缩 力， 并且保证液颈不会被 "冻"住， 而这种抗干扰的能力是现有技术中的一次 性的调控方式所无法做到的。  In the prior art, since the current waveform used is often zigzag, the larger the current is, the faster the contraction is. Therefore, the conductance curve G is only about 1 millisecond from the point C which starts to decrease slightly to the last point E. time. It can be seen from Fig. 4 that after the regulation of the welding current of the present invention, the electromagnetic contraction force is lowered due to the decrease of the current, and the conductance curve G is slowed down, and the time from the C point to the E point can be significantly increased to 2-3. In milliseconds, this provides great convenience for the regulation of the welding current. In addition, even if the liquid neck does not regularly shrink during the short circuit, the loop conductance G does not fall correspondingly, and the uninterrupted detection of the loop conductance G and the uninterrupted correspondence of the welding current i in the control method of the present invention Regulation, that is, when the loop conductance G drops, the welding current decreases; when the loop conductance G stops changing, the welding current can also stop changing; when the loop conductance G suddenly increases, the welding current can also be temporarily increased accordingly, thereby effectively It is guaranteed to provide sufficient electromagnetic contraction force to the liquid neck and to ensure that the liquid neck will not be "frozen", and this anti-interference ability cannot be achieved by the one-off regulation method in the prior art.
另外， 结合图 3、 图 5及图 6所示， 图 5中 G曲线即为图 3中短路前期的 回路电导 G 的变化曲线， 也可直接理解为液颈电导的变化曲线。 其中实线 i 曲线代表短路前期现有技术中的焊接电流的调控状况， 虚线 i代表本发明控制 方法中短路前期根据回路电导 G变化对焊接电流的调控曲线。  In addition, as shown in Fig. 3, Fig. 5 and Fig. 6, the G curve in Fig. 5 is the curve of the loop conductance G in the early stage of the short circuit in Fig. 3, and can also be directly understood as the curve of the liquid neck conductance. The solid line i curve represents the regulation state of the welding current in the prior art of the short circuit, and the broken line i represents the control curve of the welding current according to the change of the loop conductance G in the control method of the present invention.
其中如前述， 当焊接电流在燃弧后期 （即 td至 tscl之间时段）从燃弧峰值 大电流 iparJ 低为很小的基值电流 ib后， 熔滴自然下坠， 在燃弧阶段的 tscl时 刻瞬间接触熔池， 开始短路； 随后熔滴与熔池之间接触面积不断扩展， 熔滴逐 步融入熔池。 为促进熔滴金属尽快地向熔池过渡，有必要尽快地加上较大的短 路电流。但这个大电流又不能加上过早， 因为此时假如接触点还没有充分扩展 时， 过大的电流有可能把接触点立即烧掉， 形成又一次引弧， 甚至有可能把整 个熔滴都抛出去， 造成大颗粒飞溅； 但加的太晚又有可能造成过渡动力不足， 有被 "冻"住的危险。 目前现有技术中采用的控制方法都是使短路峰值大电流 。在短路开始后延迟一定时间， 如图上实线 i曲线所示， 直到 ^才加上， 这段 时间一般定为 1毫秒。 但是， 在小电流情况下， 由于已采取了其他各种措施使 熔滴和熔池都平静了下来， 基本问题不大， 而在大电流时， 当熔池翻腾猛烈， 这个时间不一定能确切保证熔滴和熔池的接触已达到肯定不会再被拉断的程 度。 为解决该问题， 本发明控制方法设置为在短路前期， 快速连续不断地检测 焊接回路中的回路电导 G, 如图 5中虚线 i所表示的那样， 当检测到回路电导 G增加时， 对焊接电流也作出相应的增加调控， 一直到电导曲线 G达到 B点， 电导增加速度明显降低， 说明液颈基本上已经稳定成形， 即进入短路中期， 此 时将焊接电流转换为短路峰值大电流 ipsc。 这种检测和调控同前面所介绍过的 图 4中所示的短路后期的电流调控一样，都是以很小的时间间隔快速连续不断 地进行的。 对 G 曲线的连续监测调控使熔滴只有在已确切地与熔池融合后才 加上短路峰值大电流， 这样保证了短路前期调控的可靠性。 As described above, when the welding current is low in the late arcing period (ie, between t d and t scl ) from the arcing peak large current i par J to a small base current i b , the droplet falls naturally, burning At the t scl of the arc phase, the molten pool is instantaneously contacted and a short circuit is started; then the contact area between the droplet and the molten pool is continuously expanded, and the droplet is gradually integrated into the molten pool. In order to promote the transition of the molten metal to the molten pool as soon as possible, it is necessary to add a larger short as soon as possible. Road current. However, this large current cannot be added too early, because if the contact point has not been fully expanded, the excessive current may burn the contact point immediately, forming another arc, and it is even possible to put the entire droplet. Throw it out, causing large particles to splash; but adding too late may cause insufficient transitional power and there is a danger of being "frozen". At present, the control methods adopted in the prior art are to make the short circuit peak current. Delay a certain time after the start of the short circuit, as shown by the solid line i curve in the figure, until ^ is added, this time is generally set to 1 millisecond. However, in the case of small currents, since various other measures have been taken to calm the droplets and the molten pool, the basic problem is not large, and at high currents, when the molten pool is tumbling, this time may not be exact. Ensure that the contact between the droplet and the molten pool has reached a level that will definitely not be broken. In order to solve this problem, the control method of the present invention is arranged to quickly and continuously detect the loop conductance G in the welding circuit in the early stage of the short circuit, as indicated by the broken line i in FIG. 5, when the loop conductance G is detected to increase, the welding is performed. The current is also adjusted accordingly. Until the conductance curve G reaches point B, the rate of increase in conductance is significantly reduced, indicating that the liquid neck has basically been stably formed, that is, into the mid-short phase, at which time the welding current is converted into a short-circuit peak current i psc . This detection and regulation is carried out in rapid succession at a small time interval, as in the case of the short-circuit current regulation shown in Fig. 4 previously described. The continuous monitoring and control of the G curve allows the droplet to be added to the short-circuit peak current only after it has been fused with the molten pool, thus ensuring the reliability of the short-circuit pre-regulation.
最后，请参阅图 6中所示的其中一个熔滴过渡的短路过渡周期 T中的电流 调控波形图， 本发明控制方法包括： 在熔滴与熔池接触的短路阶段 Tsc中对焊 接回路中的回路电导 G进行快速连续不断的检测， 并首先在液颈逐渐***的 短路前期（对应 ^至^之间时段）根据所述回路电导 G的变化对焊接电流作 出相应的逐渐增加调控， 以使液颈稳定成型而避免被烧掉、飞溅或被"冻"住； 其次， 在液颈增长稳定的短路中期 （对应 ^至 tc之间时段）， 保持短路峰值大 电流 ipsc, 以提供熔滴液颈足够的电磁收缩力； 再次， 在液颈变细的短路后期 (对应 tc至 tsc2之间时段 )根据所述回路电导 G的变化对短路负载通电的焊接 电流作出相应的减小调控，以使短路结束前的焊接电流被调控至预先设定的基 值电流 ib, 使得液颈在短路结束的 tsc2时刻平静地破坏， 进而有效避免***飞 溅或被 "冻" 住； 然后， 在短路结束后的燃弧早期（对应 tsc2至 tb之间时段）， 对电弧电压进行连续不断的检测，并根据电弧电压的变化对焊接电流作出相应 的调控， 直至电弧电压增加至 14-20v后， 即电弧再被偶然短路的可能性已被 消除时， 将焊接电流转换为燃弧峰值大电流 iparc; 再然后， 在燃弧中期（对应 tb至 td之间时段），保持燃弧峰值大电流 iparc以促进熔滴的尽快形成，从而为后 续焊接电流降低为小电流、熔滴下坠稳定和熔池平静下来提供更多时间，保证 熔滴与熔池顺利可靠地接触并融合； 最后， 在燃弧后期（对应 td至 tscl之间时 段）， 将焊接电流逐渐降低以平静步入短路阶段 Tsc。 本实施方式在图 6中用折 线所表示的电流监控调控的部分仅是示意性的，因为焊接电流的调控每次历时 时间非常短， 并且焊接电流每次变化也非常小， 所以图 6中无法真实地表示出 来。 Finally, referring to the current regulation waveform diagram in the short circuit transition period T of one of the droplet transitions shown in FIG. 6, the control method of the present invention comprises: in the short circuit phase T sc in contact with the molten pool and in the welding loop The loop conductance G performs rapid and continuous detection, and firstly adjusts the welding current according to the change of the loop conductance G in the pre-short period of the liquid neck gradually thickening (corresponding to the period between ^ and ^), The liquid neck is stably formed to avoid being burned, splashed or "frozen"; secondly, in the middle of the short circuit in which the liquid neck grows stable (corresponding to the period between ^ and t c ), the short-circuit peak current i psc is maintained to provide The molten liquid neck has sufficient electromagnetic contraction force; again, in the late stage of the liquid neck thinning (corresponding to the period between t c and t sc2 ), the welding current energizing the short-circuit load is correspondingly reduced according to the change of the loop conductance G regulation small, so that the welding current is regulated before the end of the short circuit to a predetermined base current i b, so that the neck was calmly destroyed t sc2 short circuit time ends, so as to effectively prevent splashing or explosion "Frozen"live; Then, in the early stage after the end of the short circuit arc (corresponding to the period between t sc2 t b), arc voltage is detected continuously, and make the appropriate regulation of the welding current according to a change of the arc voltage, Until the arc voltage increases to 14-20v, the possibility that the arc is accidentally shorted again has been When eliminating, the welding current is converted into the arcing peak current i parc ; then, in the middle of the arcing period (corresponding to the period between t b and t d ), the arcing peak current i parc is maintained to promote the formation of the droplet as quickly as possible. Therefore, the subsequent welding current is reduced to a small current, the droplet drop is stable, and the molten pool is calmed down to provide more time, ensuring smooth and reliable contact and fusion of the droplet and the molten pool; finally, in the late arcing period (corresponding to t d to t During the period between scl , the welding current is gradually lowered to calmly enter the short-circuit phase T sc . The portion of the current monitoring regulation of the present embodiment shown by the broken line in FIG. 6 is only illustrative, since the welding current is controlled for a very short time each time, and the welding current is changed very little every time, so that FIG. 6 cannot Truly expressed.
另外，结合图 6中上述一个熔滴过渡的短路过渡周期 T中的电流调控波形 图和该周期 T 结束后进入下一个熔滴过渡周期中的电流调控波形图， 可以看 出， 前后两个熔滴的电流调控波形图稍有不同； 因为在一次焊接过程中， 各个 熔滴的表现状态稍有差异，而本发明控制方法是对各个熔滴不同的情况对应作 出相应的调控， 进而会展示出不同的电流调控波形图， 本图 6即示意性地反映 了这种情况； 由此可见， 本发明控制方法通过对不同熔滴个性化的处理方式， 加上将现有技术中一次性的控制操作变为连续多次的过程性的调控操作，使得 本发明控制方法的控制效果更佳精确有效。  In addition, in conjunction with the current regulation waveform diagram in the short-circuit transition period T of the above-described one droplet transition in FIG. 6 and the current regulation waveform diagram in the next droplet transition period after the end of the period T, it can be seen that the two fusions before and after The current regulation waveform of the droplet is slightly different; because the performance state of each droplet is slightly different in one welding process, and the control method of the present invention controls the different conditions of each droplet, and then shows Different current regulation waveform diagrams, this figure schematically reflects this situation; it can be seen that the control method of the invention adopts a treatment method for individualized droplets, and a one-time control in the prior art. The operation becomes a continuation of a plurality of procedural regulation operations, so that the control effect of the control method of the present invention is better and more accurate.
综上所述，本发明控制方法根据熔滴液颈不同的情况对焊接电流作出相应 的连续不断的检测及调控，使控制效果更加精确有效， 进而有效防止熔化极气 体保护焊中短路过渡过程中的熔滴***飞溅或被 "冻" 住的现象的发生。 具体说明， 它们并非用以限制本发明的保护范围， 凡未脱离本发明技艺精神所 作的等效实施方式或变更均应包含在本发明的保护范围之内。  In summary, the control method of the present invention continuously and continuously detects and regulates the welding current according to different conditions of the molten liquid neck, so that the control effect is more accurate and effective, thereby effectively preventing the short circuit transition process in the gas metal arc welding. The phenomenon of the droplets exploding or splashing or being "frozen" occurs. The detailed description is not intended to limit the scope of the present invention, and the equivalents and modifications are intended to be included within the scope of the present invention.

Claims

权 利 要 求 Rights request
1. 一种熔化极气体保护焊中短路过渡过程的控制方法，其特征在于： 所述控 制方法包括在熔滴与熔池接触的短路阶段中对焊接回路中的电导进行快速连 续不断的检测，并在熔滴液颈逐渐变细的短路后期根据所述电导的变化对短路 负载通电的焊接电流作出相应的调控，并在短路结束时将焊接电流调控至预先 设定的基值电流。  A control method for a short circuit transition process in a gas metal arc welding, characterized in that: the control method comprises rapidly and continuously detecting the conductance in the welding circuit in a short circuit phase in which the droplet is in contact with the molten pool, And in the late stage of the short circuit in which the molten liquid neck is tapered, the welding current energized by the short-circuit load is adjusted according to the change of the conductance, and the welding current is regulated to a preset base current at the end of the short circuit.
2. 根据权利要求 1所述的熔化极气体保护焊中短路过渡过程的控制方法，其 特征在于： 所述控制方法还包括在熔滴形成的燃弧阶段后期，将焊接电流降低 至前述预先设定的基值电流。 特征在于：所述控制方法还包括在短路阶段中熔滴与熔池之间自点接触至液颈 稳定成型， 即短路开始时至所述电导增速明显降低时的短路前期，对焊接电流 根据所述电导的变化作出相应的调控，并在所述电导增速明显降低时将焊接电 流转换为短路峰值大电流。  2. The method of controlling a short circuit transition process in a gas metal arc welding according to claim 1, wherein: the control method further comprises: reducing a welding current to the aforementioned preset in a later stage of the arc forming phase of the droplet formation; The base current is fixed. The control method further comprises: in the short-circuiting phase, the self-point contact between the droplet and the molten pool to the liquid neck stable molding, that is, the short-circuit period from the start of the short-circuit to the time when the growth rate of the conductance is significantly reduced, and the welding current is The change in conductance is regulated accordingly, and the welding current is converted into a short-circuit peak current when the conductance growth rate is significantly reduced.
4. 根据权利要求 1或 3所述的熔化极气体保护焊中短路过渡过程的控制方 法， 其特征在于： 所述电导和焊接电流每次检测和调控的时间间隔为 10-200 微秒。 4. The method of controlling a short circuit transition process in a gas metal arc welding according to claim 1 or 3, wherein: the time interval between the conductance and the welding current for each detection and regulation is 10-200 microseconds.
5. 根据权利要求 1或 3所述的熔化极气体保护焊中短路过渡过程的控制方 法， 其特征在于： 在所述短路后期， 所述焊接电流以正比于所述电导的降低速 度进行降低调控， 即 di/dt正比于 dG/dt, 直到液颈断开。  The method for controlling a short circuit transition process in a gas metal arc welding according to claim 1 or 3, wherein: in the late stage of the short circuit, the welding current is reduced and regulated by a decreasing speed proportional to the conductance. , ie di/dt is proportional to dG/dt until the liquid neck is disconnected.
6. 根据权利要求 3所述的熔化极气体保护焊中短路过渡过程的控制方法，其 特征在于： 在所述短路前期， 所述焊接电流以正比于所述电导的增加速度进行 增力口调控。  6. The method for controlling a short circuit transition process in a gas metal arc welding according to claim 3, wherein: in the pre-short circuit period, the welding current is adjusted by a force increase ratio proportional to an increase rate of the conductance. .
7. 根据权利要求 1所述的熔化极气体保护焊中短路过渡过程的控制方法，其 特征在于： 在所述液颈中断、 短路结束后， 对电弧电压进行连续不断的检测， 并根据电弧电压的变化对焊接电流作出相应的调控， 直至电弧电压增加至 14-20v后将焊接电流转换为燃弧峰值大电流。  7. The method for controlling a short circuit transition process in a gas metal arc welding according to claim 1, wherein: after the liquid neck is interrupted and the short circuit is completed, the arc voltage is continuously detected, and according to the arc voltage. The change of the welding current is adjusted accordingly, until the arc voltage is increased to 14-20v, and the welding current is converted into a large arc current.
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