Method and device for controlling short arc in gas shielded welding

Abstract

The present invention provides a method and device for controlling a short arc in gas metal arc welding, the method comprising: when a short circuit occurs, controlling the real-time wire feeding speed to decrease to a preset value; in the arc burning stage, controlling the real-time wire feeding speed to increase, ensuring that the average wire feeding speed in the short circuit stage and the arc burning stage remains unchanged. Under the premise of ensuring that the average wire feeding speed in the short circuit stage and the arc burning stage remains unchanged, the distribution of the wire feeding speed in the short circuit and arc burning stages is distributed, so that the arc length is shortened, thereby improving the controllability of the arc.

Description

Technical Field

[0001] The invention relates to the technical field of consumable electrode gas shielded welding, and in particular to a consumable electrode gas shielded welding short arc control method and device. Background Art

[0002] For gas metal arc welding, the welding effect is directly related to the controllability of the arc. Therefore, in order to ensure a good welding effect, how to improve the controllability of the arc is an urgent problem to be solved in this field. Summary of the invention

[0003] The object of the present invention is to provide a method and device for controlling a short arc in gas metal arc welding, which can improve the controllability of the arc.

[0004] To achieve the above object, the present invention provides a method for controlling a short arc in metal electrode gas shielded welding, which comprises:

[0005] When a short circuit occurs, the real-time wire feeding speed is controlled to be reduced to a preset value;

[0006] During the arcing stage, the real-time wire feeding speed is controlled to increase to ensure that the average wire feeding speed during the short-circuiting stage and the arcing stage remains unchanged.

[0007] The present invention provides a consumable electrode gas shielded welding short arc control device for improving the controllability of the arc, which comprises:

[0008] Short-circuit speed control module, used to control the real-time wire feeding speed to a preset value when a short circuit occurs;

[0009] The arcing speed control module is used in the arcing stage to control the real-time wire feeding speed increase to ensure that the average wire feeding speed in the short-circuiting stage and the arcing stage remains unchanged.

[0010] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned metal electrode gas shielded welding short arc control method when executing the computer program.

[0011] The embodiment of the present invention controls the real-time wire feeding speed to be reduced to a preset value when a short circuit occurs; and controls the real-time wire feeding speed to be increased during the arcing stage, so as to ensure that the average wire feeding speed during the short circuit stage and the arcing stage remains unchanged. Under the premise of ensuring that the average wire feeding speed during the short circuit stage and the arcing stage remains unchanged, the distribution of the wire feeding speed during the short circuit and the arcing stage is distributed, so that the arc length is shortened, thereby improving the controllability of the arc. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following drawings are intended only to illustrate and explain the present invention, and do not limit the scope of the present invention.

[0013] Figure 1 Schematic diagram of the implementation process of the metal electrode gas shielded welding short arc control method according to an embodiment of the present invention;

[0014] Figure 2 is a schematic diagram of a PI double closed loop constructed in an embodiment of the present invention;

[0015] Figure 3 is a schematic diagram of the secondary switch control principle in an embodiment of the present invention;

[0016] Figure 4 It is a schematic diagram of controlling the wire feeding speed in a specific example of the present invention;

[0017] Figure 5 It is a schematic diagram of a wire feeding speed adjustment curve of a DC welding current of a specific example of the present invention;

[0018] Figure 6 It is a schematic diagram of a wire feeding speed adjustment curve of a pulse welding current of a specific example of the present invention;

[0019] Figure 7 It is a schematic diagram of comparison of control results in a specific example of the present invention;

[0020] Figure 8 1 is a schematic structural diagram of a short arc control device for metal electrode gas shielded welding according to an embodiment of the present invention;

[0021] Fig. 9 It is a structural schematic diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0023] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0024] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0025] The inventors have found that for metal-electrode gas shielded welding, under the premise of stable welding, the shorter the arc length, the better the controllability of the arc.

[0026] Based on the above findings, an embodiment of the present invention provides a method for controlling a short arc in gas metal arc welding, which is used to improve the controllability of the arc. Figure 1 As shown, including:

[0027] Step 101: When a short circuit occurs, controlling the real-time wire feeding speed to decrease to a preset value;

[0028] Step 102: During the arcing stage, the real-time wire feeding speed is controlled to increase to ensure that the average wire feeding speed during the short-circuiting stage and the arcing stage remains unchanged.

[0029] In a specific embodiment, when a short circuit occurs, the real-time wire feeding speed is controlled to be reduced to a preset value; in the arcing stage, the real-time wire feeding speed is controlled to be increased to ensure that the average wire feeding speed in the short circuit stage and the arcing stage remains unchanged. Under the premise of ensuring that the average wire feeding speed in the short circuit stage and the arcing stage remains unchanged, the stability of welding is ensured. By allocating the distribution of wire feeding speed in the short circuit and arcing stages, the real-time wire feeding speed is reduced in the short circuit stage, that is, the welding current is reduced, so that the arc length is shorter, thereby improving the controllability of the arc and further ensuring the stability of welding.

[0030] First, when a short circuit occurs, the real-time wire feeding speed is controlled to be reduced to a preset value. In specific implementation, the preset value is a speed value pre-set based on the welding condition, and the speed value is a positive number or zero, that is, the real-time wire feeding speed is controlled to be reduced or stopped. The preset value is set based on a given wire feeding speed. When the given wire feeding speed is lower than a preset threshold, for example, 10 meters per minute, the preset value is 0; when the given wire feeding speed is higher than or equal to the preset threshold, the preset value is proportional to the given wire feeding speed, that is, the larger the given wire feeding speed, the larger the preset value, and the proportional coefficient is not fixed, but not greater than 80%.

[0031] Then, in the arcing stage, the real-time wire feeding speed is controlled to increase to ensure that the average wire feeding speed in the short-circuit stage and the arcing stage remains unchanged. In addition, the welding current in the arcing stage is not limited, and the welding current in the arcing stage can be a DC output or a pulse output. In the specific implementation, based on the PI double closed-loop control method, a PI double closed-loop is constructed to control the real-time wire feeding speed in the arcing stage to increase, so that the average wire feeding speed in the short-circuit stage and the arcing stage is the given wire feeding speed.

[0032] Double closed-loop control is a basic control method based on the principle of automatic control. The basic PI double closed-loop control method contains two control parts: the current inner loop PI controller and the voltage outer loop PI controller. The current inner loop controller uses the current negative feedback to make the current flowing through the inductor a current of a given amplitude and phase. The function of the voltage outer loop is to introduce negative feedback of the voltage so that the DC side voltage is stabilized to a given value. By extending it to the control of wire feeding speed, a PI double closed loop can be constructed based on its control principle.

[0033] Specifically, if Figure 2As shown, a PI double closed loop is constructed, wherein the PI double closed loop includes:

[0034] Real-time wire feeding speed control inner loop and average wire feeding speed control outer loop;

[0035] The real-time wire feeding speed control inner loop takes the real-time wire feeding speed as the control target;

[0036] The average wire feeding speed controls the outer loop, taking the difference between the average wire feeding speed and the given wire feeding speed as input, and the average wire feeding speed as the control target.

[0037] The real-time wire feeding speed control inner loop adopts the real-time wire feeding speed adjustment method, with the real-time wire feeding speed and the given wire feeding speed at a specific moment as input, after passing through the inner loop PI controller, combined with the motor transfer function G(S) (used to describe the relationship between the conduction angle and the wire feeding speed), the actual wire feeding speed is obtained, and there is a wire feeding feedback transfer function F(S) as the inner loop closed-loop feedback. The average wire feeding speed control outer loop takes the difference between the average wire feeding speed and the given wire feeding speed as input, and the output after passing through the outer loop PI controller is used as part of the input of the real-time wire feeding speed control inner loop closed-loop, and there is a wire feeding feedback transfer function V(S) as the outer loop closed-loop feedback.

[0038] Set the given wire feeding speed to S g , the actual wire feeding speed is: S A ;

[0039] Then node 1 can be represented as:

[0040] ΔS=S g -S A ×V(S) (1)

[0041] Wherein, V(S) is the average value of the wire feeding speed in a sampling period. The duration of the sampling period is generally short, for example, 20 ms.

[0042] again:

[0043]

[0044] From formulas (1) and (2), we can see that node 2 can be expressed as:

[0045] N2(S)=M(s)+K P1 ×ΔS+K I1 ×∫ΔS-S A ×F(s) (3)

[0046] Among them, F(s) is the feedback of the instantaneous value of wire feeding speed;

[0047] K P1 : Proportional term coefficient of the outer loop PI;

[0048] K I1 : Integral term coefficient of outer loop PI;

[0049] Then node 3 can be expressed as:

[0050] N3(S)=(K P2 N2(S)+K I2 ·∫N2(S))·G(S) (4)

[0051] K P2 : Proportional term coefficient of the inner loop PI;

[0052] K I2 : Integral term coefficient of the inner loop PI.

[0053] It can be seen that the PI double closed loop constructed above can achieve the control purpose of gradually ensuring that the average wire feeding speed is consistent with the preset wire feeding speed while the wire feeding is started in the arcing stage after the short-circuit stage.

[0054] In a specific embodiment, the provided metal electrode gas shielded welding short arc control method further includes: when the real-time wire feeding speed changes during the short circuit stage, controlling the secondary switch to close. Figure 3 The figure shows a schematic diagram of the secondary switch control principle, that is, when a short circuit occurs, the secondary switch is closed, and the current is rapidly reduced to the minimum value to prevent spatter, so as to complete the short circuit transition and reduce the heat input; after the short circuit is over, the secondary switch is opened to reduce spatter. In a specific embodiment, according to the short circuit situation or welding experience summary, the working time of the secondary switch is pre-set to ensure that the secondary switch is closed at the moment when the real-time wire feeding speed changes, and is opened with a delay according to the preset working time.

[0055] By controlling the wire feeding speed and coordinating the secondary switch, stable welding with a smaller arc length is achieved, thereby improving arc stability and welding results.

[0056] In order to better illustrate the metal electrode gas shielded welding short arc control method provided in the embodiment of the present invention, a specific example is also provided in the specific embodiment of the present invention. The control of the wire feeding speed in the specific embodiment is as follows: Figure 4 As shown, the specific control is as follows Figure 2 The PI double closed loop is shown.

[0057] Figure 5 The wire feeding speed adjustment curve of DC welding current is shown. Figure 6The figure shows the wire feeding speed adjustment curve of the pulse welding current, where the secondary switch is closed at the moment when the wire feeding speed changes during the short circuit stage. From the current change curve, it can be seen that the section of the curve where the current suddenly drops is the period when the secondary switch is closed. By using the secondary switch before and after the short circuit occurs, the short circuit transition is completed.

[0058] In this specific example, a DC welding current of 120A was designed for testing. Since 120A is a standard short-circuit transition current segment, the effectiveness of the algorithm can be fully verified by using this current segment for testing.

[0059] As shown in Table 1, it is a welding specification table and number of this specific example. 1# and 2# are experimental groups applying the metal electrode gas shielded welding short arc control method in the embodiment of the present invention, and 3# and 4# are comparative groups.

[0060] DC 120A, specification number 1#, 2#, 3#, 4# four groups of test conditions are as follows Figure 7 shown.

[0061] Table 1 Welding specification table

[0062]

[0063] 1# is compared with 3#, and 2# is compared with 4#. From a macroscopic analysis, it can be seen that after using the metal electrode gas shielded welding short arc control method provided by the embodiment of the present invention, the welding stability is significantly improved. Especially when the welding voltage is relatively low, the welding stability is greatly improved.

[0064] For further analysis of the waveform, 20 groups of short-circuit transition times at fixed time positions are selected as basic data for analysis. The principles of the analysis include:

[0065] The smaller the average value of the short-circuit transition time is, the smoother the short-circuit transition is; conversely, the higher the probability of thread top-off is and the more difficult the transition is.

[0066] The smaller the sum of squares of the average value difference of the short-circuit transition time, the more uniform the short-circuit transition is. Otherwise, it means that the short-circuit process varies greatly, the transition uniformity is poor, and the short-circuit transition is unstable.

[0067] The comparison results are shown in Table 2.

[0068] Table 2 DC 120A short circuit time comparison analysis table (unit: ms)

[0069] 1# 2# 3# 4# Group 1 short circuit transition time 3.15 4.15 3.48 4.42 Short circuit transition time of group 2 2.5 3.3 3.1 4.18 Group 3 short circuit transition time 4.25 5.55 2.48 3.9 Group 4 short circuit transition time 3.1 5.65 3.68 3.08 Group 5 short circuit transition time 2.55 2.85 3.1 3 Group 6 short circuit transition time 2.85 3.45 2.9 3.26 Group 7 short circuit transition time 3.10 4.2 4.26 2.58 Group 8 short circuit transition time 2.95 2.2 2.85 2.2 Group 9 short circuit transition time 2.55 5.1 4.42 4.7 Group 10 short circuit transition time 3.25 2.75 3.22 2.8 Group 11 short circuit transition time 3.2 5.25 3.3 2.92 Group 12 short circuit transition time 4.25 2.7 2.64 4.8 Group 13 short circuit transition time 2.65 3.85 3.62 3.34 Group 14 short circuit transition time 5.1 2.8 3.08 5.58 Group 15 short circuit transition time 3.75 3.45 3.78 7.84 Group 16 short circuit transition time 4.25 2.85 3.86 7.96 Group 17 short circuit transition time 3.85 3 2.58 10.74 Group 18 short circuit transition time 3.3 2.95 2.46 9.1 Group 19 short circuit transition time 3.65 2.75 3.1 8.92 Group 20 short circuit transition time 4.15 2.85 2.62 9.04 average value 3.4 3.6 3.2 5.2 Sum of squares of mean differences 9.6 21.2 6.2 136.3

[0070] It can be seen from Table 2 that after using the metal electrode gas shielded welding short arc control method provided by the embodiment of the present invention, when the welding voltage is high (1# and 3#), the average value of the short circuit transition time and the sum of the squares of the difference between the average values ​​of the short circuit transition time are not much different; while when the welding voltage is low (2# and 4#), after the metal electrode gas shielded welding short arc is controlled, these two indicators have obvious advantages, that is, the stability is greatly improved.

[0071] It can be seen that after applying the short arc control method for metal electrode gas shielded welding provided by the embodiment of the present invention, stable welding with a shorter arc length is achieved, and a better welding effect can be obtained.

[0072] Based on the same inventive concept, the embodiment of the present invention also provides a short arc control device for metal electrode gas shielded welding, the principles of solving the problems are similar, and the repeated parts are not repeated. The specific structure is as follows Figure 8 As shown, including:

[0073] The short-circuit speed control module 801 is used to control the real-time wire feeding speed to be reduced to a preset value when a short circuit occurs;

[0074] The arcing speed regulating module 802 is used to control the real-time wire feeding speed to increase during the arcing stage, so as to ensure that the average wire feeding speed during the short-circuiting stage and the arcing stage remains unchanged.

[0075] The short arc control device for metal-electrode gas shielded welding provided in the specific embodiment is Figure 8 On the basis of the present invention, it also includes: a secondary switch control module, which is used to control the secondary switch to close when the wire feeding speed changes in real time during the short circuit stage.

[0076] In a specific embodiment, the arcing speed regulation module 802 is specifically used to: construct a PI double closed loop based on the PI double closed loop control method, control the real-time wire feeding speed in the arcing stage to increase, so that the average wire feeding speed in the short circuit stage and the arcing stage is a given wire feeding speed.

[0077] An embodiment of the present invention further provides a computer device, Fig. 9 Schematic diagram of a computer device in an embodiment of the present invention. The computer device can implement all steps in the metal electrode gas shielded welding short arc control method in the above embodiment. The computer device specifically includes the following contents:

[0078] Processor (processor) 901, memory (memory) 902, communication interface (CommunicationsInterface) 903 and communication bus 904;

[0079] The processor 901, the memory 902, and the communication interface 903 communicate with each other through the communication bus 904; the communication interface 903 is used to realize information transmission between related devices;

[0080] The processor 901 is used to call the computer program in the memory 902, and the processor implements the metal electrode gas shielded welding short arc control method in the above embodiment when executing the computer program.

[0081] In summary, the method and device for controlling short arc in metal-metal gas shielded welding provided in this specific embodiment have the following advantages:

[0082] When a short circuit occurs, the real-time wire feeding speed is controlled to be reduced to a preset value; during the arcing stage, the real-time wire feeding speed is controlled to be increased to ensure that the average wire feeding speed during the short circuit and arcing stages remains unchanged. Under the premise of ensuring that the average wire feeding speed during the short circuit and arcing stages remains unchanged, the distribution of the wire feeding speed during the short circuit and arcing stages is achieved, making the arc length shorter, thereby improving the controllability of the arc, and further ensuring the stability of welding and good welding results.

[0083] Although the present invention provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in sequence or in parallel according to the method shown in the embodiments or the drawings (for example, in a parallel processor or multi-threaded processing environment).

[0084] It should be understood by those skilled in the art that the embodiments of this specification may be provided as methods, devices (systems) or computer program products. Therefore, the embodiments of this specification may take the form of complete hardware embodiments, complete software embodiments or embodiments combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0085] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0088] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. In this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0089] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or replacement of these aspects and / or embodiments. Moreover, each aspect and / or embodiment of the present invention may be used alone or in combination with one or more other aspects and / or embodiments thereof.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for controlling short arc in metal-electrode gas shielded welding, characterized in that: include: When a short circuit occurs, the real-time wire feeding speed is controlled to be reduced to a preset value; In the arcing stage, the real-time wire feeding speed is controlled to increase to ensure that the average wire feeding speed in the short-circuiting stage and the arcing stage remains unchanged, including: Based on the PI double closed-loop control method, a PI double closed-loop is constructed to control the real-time wire feeding speed in the arcing stage to increase so that the average wire feeding speed in the short-circuiting stage and the arcing stage is a given wire feeding speed; wherein the PI double closed-loop includes: Real-time wire feeding speed control inner loop and average wire feeding speed control outer loop; The real-time wire feeding speed control inner loop takes the real-time wire feeding speed as the control target; The average wire feeding speed control outer loop takes the difference between the average wire feeding speed and the given wire feeding speed as input, and takes the average wire feeding speed as the control target; When the real-time wire feeding speed changes in the short-circuit stage, the secondary switch is controlled to close, the current is reduced to the minimum value, and the arcing stage is transitioned to the short-circuit stage, and the secondary switch is opened after the short-circuit is completed.

2. A short arc control device for metal-metal gas shielded welding, characterized in that: include: Short-circuit speed control module, used to control the real-time wire feeding speed to reduce to a preset value when a short circuit occurs; The arcing speed control module is used to construct a PI double closed loop based on the PI double closed loop control method to control the increase of the real-time wire feeding speed in the arcing stage so that the average wire feeding speed in the short circuit stage and the arcing stage is the given wire feeding speed; The secondary switch control module is used to control the secondary switch to close when the wire feeding speed changes in real time during the short circuit stage.

3. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for controlling the short arc of gas metal arc welding according to claim 1 is implemented.

4. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and in response to the computer program being executed by the processor, the operation of the metal electrode gas shielded welding short arc control method of claim 1 is implemented.

5. A computer program product, characterized in that The computer program product includes a computer program, and when the computer program is executed by a processor, it implements: the metal electrode gas shielded welding short arc control method according to claim 1.

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