CN109047990B

CN109047990B - Control method for contact arc striking of gas metal arc welding

Info

Publication number: CN109047990B
Application number: CN201811230359.2A
Authority: CN
Inventors: 苏立虎; 谷孝满; 李江
Original assignee: Panasonic Welding Systems Tangshan Co Ltd
Current assignee: Panasonic Welding Systems Tangshan Co Ltd
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2020-11-10
Anticipated expiration: 2038-10-22
Also published as: CN109047990A

Abstract

The disclosure relates to the field of consumable electrode arc welding, and provides a control method for contact arc ignition of consumable electrode gas shielded welding, wherein the contact arc ignition is abnormal arc ignition caused by the fact that a welding wire contacts with a workpiece before a welding gun switch is closed, and the control method comprises the following steps: after a welding gun switch is closed and before a wire feeding motor rotates, whether the arc striking of the gas shielded metal arc welding is normal arc striking or contact arc striking is judged; if the contact arc ignition is judged, the wire feeding motor is kept not to act for a preset delay time after the feedback current is detected; and after the preset delay time, enabling the wire feeding motor to start wire feeding action and increasing the wire feeding speed to a preset wire feeding speed value. The control method for the gas metal arc-protection welding contact arc striking can judge whether the arc striking is carried out before entering the slow wire feeding stage, the detection is timely and accurate, and the reliability is high. Meanwhile, arc striking parameters do not need to be adjusted again, time is saved, and the success rate and the reliability of arc striking can be improved.

Description

Control method for contact arc striking of gas metal arc welding

Technical Field

The disclosure relates to the field of consumable electrode arc welding, in particular to a control method for contact arc striking of consumable electrode gas shielded welding.

Background

With the development of welding technology, in order to improve production efficiency, for example, metal Active Gas Arc welding (MAG) is increasingly applied to actual welding operation, wherein MAG (metal Active Gas Arc welding) is a short name for Gas metal Arc welding, and is a mixed Gas shielded welding formed by adding a small amount of oxidizing Gas (oxygen, carbon dioxide or a mixed Gas thereof) into argon. The mixed gas of 80% Ar and 20% carbon dioxide is commonly used in China, and the argon accounts for a large proportion in the mixed gas, so the mixed gas is often called argon-rich mixed gas shielded welding.

The welding process of gas metal arc welding may be performed manually by a welding technician or by an automated welding apparatus. During normal welding, a welding wire is usually away from a base metal by a certain distance, a welding gun switch is closed, the welding wire contacts the base metal through a slow wire feeding process, and at the moment, electric arc is ignited to start welding operation. This process is described as: closing a welding gun switch, opening an air valve to supply protective gas, generating no-load voltage, enabling a welding wire to contact a workpiece in a slow wire feeding process, igniting an electric arc, accelerating a wire feeding motor to rotate to a set wire feeding speed, and entering a main welding process. The waveform diagram of normal arc ignition can refer to fig. 1.

The schematic illustration of the normal arc initiation waveform of figure 1 is as follows:

the 0A stage is as follows: the welding gun switch is closed, and no-load voltage is generated by feeding air in advance.

The AB stage is as follows: and the motor slowly feeds the wire to feed the welding wire to the workpiece.

The BC stage is as follows: the welding wire contacts the workpiece and the arc is ignited.

The CD stage is: the wire feeding motor accelerates to a set wire feeding speed value.

Stage C 'D': and in the dotted line part, the matched wire feeding energy is obtained in the wire feeding and climbing process.

And C ', the welding power supply is matched with the waveform parameters, and after the time C' C is delayed, the wire feeding motor starts to act.

In the actual production process, due to the task requirements, the time is urgent or limited by the workpiece size, the welding position such as the case of beveling a thick plate, the case of a small bevel angle, or the difference of welding methods of welding operators. When welding, the welding wire contacts with a workpiece first inevitably, then a welding gun switch is switched on to carry out welding operation, at the moment, arc striking is unsmooth due to contact, and very large splashing or welding wire burning is caused but a molten pool is not formed or the welding wire is broken and then arc striking is carried out again, so that poor welding is caused during arc striking, unqualified welding seams are formed, and the welding quality of products is influenced. The waveform of the contact arc ignition can be seen from fig. 2.

Fig. 2 illustrates a schematic diagram of a contact arc initiation waveform as follows:

the wire feed sequence description of fig. 2 is consistent with fig. 1, with the following differences:

and at the stage of 0A, closing a welding gun switch, detecting the existing current and generating an electric arc.

According to a normal arc striking time sequence, the energy matching and the actual wire feeding speed generate larger deviation, so that poor arc striking is caused, and welding defects are generated.

As can be seen from fig. 2, in the AB phase and the slow wire feeding phase, the motor has already started to rotate, and at this time, there is a current detection but no matching of the welding waveform parameters, resulting in wire feeding but no matching of energy, and the matching of a smaller energy is not started until the wire feeding speed enters the climbing phase. In this case 3 cases may occur: 1. huge welding spatter is generated. 2. The wire is burned red without arcing. 3. The energy is low, the welding wire breaks, the motor continues to feed the wire, and the arc is started again after the welding wire contacts the workpiece. In all cases 3, the initial welding arc striking is not smooth, and welding defects are caused.

Therefore, designing a new method for controlling the contact arc striking of the gas metal arc welding is a technical problem to be solved urgently at present.

The above information disclosed in this background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a control method for contact arc striking of gas metal arc welding, which solves the problem that the contact arc striking generates large splashing to cause poor arc striking or welding defects caused by arc striking, does not need to readjust arc striking parameters, can save time and improve the success rate and reliability of arc striking.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows, or in part will be learned by practice of the disclosure.

According to an embodiment of the present disclosure, a method for controlling a contact arc for gas metal arc welding is disclosed, wherein the contact arc is an abnormal arc caused by a welding wire contacting a workpiece before closing a welding gun switch, the method comprising:

after a welding gun switch is closed and before a wire feeding motor rotates, whether the arc striking of the gas shielded metal arc welding is normal arc striking or contact arc striking is judged;

if the contact arc ignition is judged, the wire feeding motor is kept not to act for a preset delay time after the feedback current is detected; and

and after the preset delay time, enabling the wire feeding motor to start wire feeding action and increasing the wire feeding speed to a preset wire feeding speed value.

In an exemplary embodiment of the present disclosure, the control method further includes: if the arc is normally ignited, a normal consumable electrode gas shielded welding process is carried out.

According to an embodiment of the present disclosure, the determining whether arc striking of gas metal arc welding is normal arc striking or contact arc striking after the welding gun switch is turned on and before the wire feeding motor rotates includes: and detecting the deviation between the actually fed back voltage and the no-load voltage within a preset detection time after the welding gun switch is closed, if the deviation is not greater than a preset voltage value, judging that the arc is normally ignited, and otherwise, judging that the arc is in contact ignition.

According to an embodiment of the present disclosure, the predetermined detection time is 1.1-1.5 ms; the predetermined voltage value is 4-6V.

According to an embodiment of the present disclosure, the predetermined detection time is 1.3 ms; the predetermined voltage value is 5V.

According to an embodiment of the present disclosure, the determining whether arc striking of gas metal arc welding is normal arc striking or contact arc striking after the welding gun switch is turned on and before the wire feeding motor rotates includes: and detecting the current fed back actually within a preset detection time after the welding gun switch is closed, if the current is not greater than a preset current value, judging that the arc is normally ignited, and otherwise, judging that the arc is contacted and ignited.

According to an embodiment of the present disclosure, the predetermined detection time is 1.1-1.5 ms; the predetermined current value is 9-11A.

According to an embodiment of the present disclosure, the predetermined detection time is 1.3 ms; the predetermined current value is 10A.

According to an embodiment of the present disclosure, the predetermined delay time has the same end point as the slow wire feeding stage in the normal gas metal arc welding process.

According to the method of some exemplary embodiments of the disclosure, whether the arc striking is contacted or not can be judged before entering the slow wire feeding stage, the detection is timely and accurate, and the reliability is high.

According to the control method of some exemplary embodiments of the disclosure, arc striking parameters do not need to be readjusted, time is saved, and the success rate and reliability of arc striking can be improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.

Fig. 1 shows a schematic diagram of a normal arc starting waveform.

Fig. 2 shows a schematic view of a contact arc starting waveform.

FIG. 3 illustrates a flow chart of a method of controlling a metal arc contact arc start in accordance with an exemplary embodiment of the present disclosure.

Fig. 4 is a timing diagram illustrating contact starting in a control method of contact starting for gas metal arc welding according to an exemplary embodiment of the present disclosure.

Fig. 5 shows a timing diagram for the wire feed of a normal arc start weld.

Fig. 6 illustrates a timing diagram for wire feeding for contact arc welding in a control method for contact arc ignition for gas metal arc welding according to an exemplary embodiment of the present disclosure.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the subject matter of the present disclosure can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and the like.

It is noted that in the drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. Also, it will be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or layer or intervening layers may also be present. In addition, it will be understood that when an element or layer is referred to as being "under" another element or layer, it can be directly under the other element or intervening layers or elements may also be present. In addition, it will also be understood that when a layer or element is referred to as being "between" two layers or elements, it can be the only layer between the two layers or elements, or more than one intermediate layer or element may also be present. Like reference numerals refer to like elements throughout.

When the consumable electrode gas shielded welding is used for arc striking, a welding wire is firstly contacted with a workpiece, then a welding gun switch is switched on for welding, and the welding defect that the arc striking is poor or the arc striking cannot be carried out due to the fact that the welding wire is contacted with the arc striking to generate large splashing is overcome.

The invention aims to provide a control method for contact arc ignition of gas metal arc welding, wherein the contact arc ignition is abnormal arc ignition caused by the fact that a welding wire contacts a workpiece before a welding gun switch is closed, and the control method comprises the following steps: after a welding gun switch is closed and before a wire feeding motor rotates, whether the arc striking of the gas shielded metal arc welding is normal arc striking or contact arc striking is judged; if the contact arc ignition is judged, the wire feeding motor is kept not to act for a preset delay time after the feedback current is detected; and after the preset delay time, enabling the wire feeding motor to start wire feeding action and increasing the wire feeding speed to a preset wire feeding speed value. The control method for the gas metal arc-protection welding contact arc striking can judge whether the arc striking is carried out before entering the slow wire feeding stage, the detection is timely and accurate, and the reliability is high. Meanwhile, arc striking parameters do not need to be adjusted again, time is saved, and the success rate and the reliability of arc striking can be improved.

The method for controlling the contact arc starting of the gas metal arc welding of the present disclosure is described in detail below with reference to fig. 3-6, wherein fig. 3 shows a flow chart of a method for controlling the contact arc starting of the gas metal arc welding of the present disclosure according to an exemplary embodiment of the present disclosure; FIG. 4 illustrates a timing diagram of contact arcing in a method of controlling contact arcing for gas metal arc welding according to an exemplary embodiment of the present disclosure; FIG. 5 shows a timing diagram for wire feed for normal arc starting welding; fig. 6 illustrates a timing diagram for wire feeding for contact arc welding in a control method for contact arc ignition for gas metal arc welding according to an exemplary embodiment of the present disclosure.

As shown in fig. 3, according to an embodiment of the present disclosure, a method for controlling contact arc ignition in gas metal arc welding is disclosed, wherein the contact arc ignition is abnormal arc ignition caused by a welding wire contacting a workpiece before closing a welding gun switch, the method comprising:

at S302, after a welding gun switch is closed and before a wire feeding motor rotates, whether the arc striking of the consumable electrode gas shielded welding is normal arc striking or contact arc striking is judged.

According to an embodiment of the present disclosure, the determining whether arc striking of gas metal arc welding is normal arc striking or contact arc striking after the welding gun switch is turned on and before the wire feeding motor rotates includes: and detecting the deviation between the actually fed back welding voltage and the no-load voltage within a preset detection time after the welding gun switch is closed, if the deviation is not greater than a preset voltage value, judging that the arc is normally ignited, and otherwise, judging that the arc is in contact ignition.

The existing judging method is mainly characterized in that after a welding gun switch is closed, if arc striking is performed through contact, short circuit is judged to occur according to voltage in a program, and then short circuit processing is performed. The method has the defects that when the short circuit, namely the contact arc ignition, is detected, the current is detected, the program enters the stages of slow wire feeding and the like, and the judgment is delayed. The control method of the embodiment of the disclosure can judge whether to contact with the arc striking before entering the slow wire feeding stage, the detection is timely and accurate, and the reliability is very high.

According to an embodiment of the present disclosure, the predetermined detection time is 1.1-1.5ms (milliseconds); the predetermined voltage value is 4-6V (volts).

According to an embodiment of the present disclosure, the determining whether arc striking of gas metal arc welding is normal arc striking or contact arc striking after the welding gun switch is turned on and before the wire feeding motor rotates includes: and detecting the actually fed back welding current within a preset detection time after closing a welding gun switch, judging normal arc striking if the actually fed back welding current is not greater than a preset current value, and otherwise, judging contact arc striking.

According to an embodiment of the present disclosure, the predetermined detection time is 1.1-1.5 ms; the predetermined current value is 9-11A (amperes).

For example, within 1.3ms after a welding gun switch is closed, by detecting the deviation between the actual feedback voltage value and the no-load voltage, if the deviation is within 5V, normal arc striking is considered, and when the deviation exceeds 5V, contact arc striking is considered, or when the feedback current is greater than 10A, contact arc striking is considered, so that whether contact arc striking is performed or not can be judged before the slow wire feeding stage is started, the detection is timely and accurate, and the reliability is high.

At S304, if it is determined that contact arc initiation is present, the wire feed motor is maintained inactive for a predetermined delay time after the presence of the feedback current is detected. As shown in fig. 4, after the current is detected (i.e. starting from point a in fig. 4), the wire feeding motor is not operated, and the wire feeding is rotated after a delay (i.e. from C' to C in fig. 4), so as to improve the output energy of the welding power source and enable smoother arc striking.

According to an embodiment of the present disclosure, the predetermined delay time has the same end point as the slow wire feeding stage in the normal gas metal arc welding process. Namely, skipping the slow wire feeding stage of the normal arc striking process, or keeping the wire feeding motor inactive until the end of the slow wire feeding stage corresponding to the normal arc striking process.

At S306, after the predetermined time, the wire feeding motor starts wire feeding and increases the wire feeding speed to a predetermined wire feeding speed value, as shown in C to D in fig. 4, that is, after the delay time elapses, the wire feeding motor operates, and directly enters a climbing stage (i.e., an acceleration rising stage) without a slow wire feeding process of normal arc striking and accelerates to a preset wire feeding speed value. In the aim of processing, the rotating speeds of the motors are different in the slow wire feeding stage and the climbing stage, the rotating speeds are also changed in real time, different set currents are different, energy matching is complex, the parameters of materials, wire diameters and gas arc striking of different welding specifications need to be readjusted, workload is large, and proper welding parameters cannot be matched. The wire feeding is delayed, so that larger energy is matched, the slow wire feeding stage is skipped, the ideal effect can be achieved by directly using the current parameters, the arc striking parameters do not need to be adjusted again, the time is saved, and the success rate and the reliability of arc striking can be improved.

Specifically, after the contact arc is detected through S302, the time sequence is first processed/adjusted, where the original time sequence (i.e., the normal gas shield welding time sequence/flow) is the stages of closing the welding gun switch, feeding gas in advance to output no-load voltage, feeding wire slowly, and keeping wire slowly, and the generated arc enters the climbing stage, and then matches with the corresponding energy. If the contact arc is detected, the time sequence is as follows: closing a welding gun switch, detecting as contact arc striking, generating electric arc, delaying wire feeding, directly entering a climbing stage, and re-matching energy.

Fig. 5 and 6 are welding wire feeding timing diagrams for normal arc ignition and contact arc ignition, wherein the ordinate is the actual wire feeding speed of the motor, the abscissa is time, the time unit T is ms (millisecond), fig. 5 is normal arc ignition, and the whole welding process goes through a complete timing sequence. Fig. 6 is a contact arc strike, all sequences after the welding process has gone through a hill climb. The dashed line in both figures, i.e., C 'D', is the welding parameter value that matches the actual wire feed, and may match the waveform parameter value of 3m/min when the actual wire feed speed is 2m/min (meters/minute). And C 'point welding is matched with the waveform parameters, the welding power supply outputs energy, and the wire feeding motor starts to act after C' C time is delayed.

According to an embodiment of the present disclosure, the wire feeding motor starts the wire feeding action and increases the wire feeding speed to a predetermined wire feeding speed value by a constant acceleration, as shown in fig. 6, where C to D are oblique straight lines. However, the present disclosure is not limited thereto, and may be performed by a variable acceleration, for example, C to D in fig. 6 may also be an arc line or a broken line.

According to an embodiment of the present disclosure, the predetermined wire feed speed value is the same as the wire feed speed value of the main welding stage in the normal gas metal arc welding process. However, the disclosure is not limited thereto, and other wire feeding speed values may be adopted according to actual needs.

As is readily appreciated by those skilled in the art from the foregoing detailed description, the method of controlling the arc initiation of the gas metal arc welding contact according to the exemplary embodiments of the present disclosure has one or more of the following advantages.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method of controlling contact arc initiation for gas metal arc welding, wherein contact arc initiation is abnormal arc initiation due to contact of a welding wire with a workpiece prior to closing a torch switch, the method comprising:

after the preset delay time, enabling the wire feeding motor to start wire feeding action and increasing the wire feeding speed to a preset wire feeding speed value;

the end point of the preset delay time is the same as the end point of the slow wire feeding stage in the normal gas metal arc welding process.

2. The method of claim 1, further comprising: if the arc is normally ignited, a normal consumable electrode gas shielded welding process is carried out.

3. The method of claim 1, wherein determining whether arc initiation for gas metal arc welding is normal arc initiation or contact arc initiation after closing a torch switch and prior to rotation of a wire feed motor comprises: and detecting the deviation between the actually fed back voltage and the no-load voltage within a preset detection time after the welding gun switch is closed, if the deviation is not greater than a preset voltage value, judging that the arc is normally ignited, and otherwise, judging that the arc is in contact ignition.

4. The method of claim 3, wherein the predetermined detection time is 1.1-1.5 ms; the predetermined voltage value is 4-6V.

5. The method of claim 4, wherein the predetermined detection time is 1.3 ms; the predetermined voltage value is 5V.

6. The method of claim 1, wherein determining whether arc initiation for gas metal arc welding is normal arc initiation or contact arc initiation after closing a torch switch and prior to rotation of a wire feed motor comprises: and detecting the current fed back actually within a preset detection time after the welding gun switch is closed, if the current is not greater than a preset current value, judging that the arc is normally ignited, and otherwise, judging that the arc is contacted and ignited.

7. The method of claim 6, wherein the predetermined detection time is 1.1-1.5 ms; the predetermined current value is 9-11A.

8. The method of claim 7, wherein the predetermined detection time is 1.3 ms; the predetermined current value is 10A.

9. The method of claim 1, wherein initiating wire feed motion by the wire feed motor and increasing the wire feed speed to a predetermined wire feed speed value is performed at a constant acceleration.

10. The method of claim 1, wherein the predetermined wire feed speed value is the same as a wire feed speed value for a primary welding stage in a normal sweet gas shield welding process.