Gas metal arc welding equipment and arcing method

Abstract

The invention discloses gas metal arc welding equipment and an arcing method.The equipment comprises a welding gun, a welding power source and a shielding gas device, the welding power source and the shielding gas device are connected with the welding gun, the welding gun is connected with a wire disc through a servo wire feeder, and the welding power source comprises a main power source and an auxiliary power source. The double-power-supply structure of the auxiliary power supply and the main power supply is adopted, the auxiliary power supply is used for outputting arc striking current, small and stable electric arcs are formed in cooperation with wire drawing separation of the servo wire feeder after welding wires make contact with a welding product, the effects that arcing is stable, the welding wires are not melted or melted and not exploded can be achieved, arc breaking is avoided, the arc striking success rate is high, and the production efficiency is high. And after the electric arc is stable, the main power supply outputs the welding current to carry out normal set welding, so that the welding arc-starting splashing in a conventional large current impact arc-starting mode can be effectively avoided, the arc-starting success rate is improved, and the welding quality is improved.

Description

Technical Field

[0001] The present invention relates to a welding device, specifically a gas metal arc welding device and an arc starting method. Background Art

[0002] With the development of industrial production and the progress of technology, welding technology is increasingly widely used in the manufacturing industry. Among them, gas metal arc welding, as an efficient welding method, has the characteristics of fast welding speed and good welding quality, and is widely used in the welding of various metal materials. In practical applications, the arc starting process of gas metal arc welding has received extensive attention, and higher requirements have been put forward for the arc starting success rate, welding spatter, and welding quality during the gas shielded welding process in various industries.

[0003] Current gas shielded welding power sources all adopt a single power output mode, mostly the impact large current arc starting method. In the arc starting process, the consumable electrode wire is mainly fed at a certain wire feeding speed. When starting the arc, a large current is output. When the wire contacts the workpiece, the wire instantly short-circuits and explodes and melts, forming a gap distance between the wire and the product, and the resulting spatial ionization generates an arc. Especially for gas shielded welding with thick wires of large diameter, when starting the arc, the PWM circuit is fully opened, and the maximum welding current is output to ensure that the wire instantly melts and burns out enough discharge distance to form an arc and complete the arc starting. However, this method has great deficiencies:

[0004] First, due to the uncontrollability of the current conduction when the wire feeds and contacts the base material, such as uncertain factors such as the oxide film on the product surface, the wire often adheres to the base material, affecting the generation of the arc space and resulting in arc starting failure, thus making the arc starting success rate uncertain.

[0005] Second, when performing gas shielded welding with thick wires of large diameter, the power of the welding power source is very large, mostly around 1000A. If the arc starting current is too small during arc starting, the melting distance of the wire is short, the discharge distance is insufficient, and a stable arc cannot be formed, resulting in arc starting failure. If a power source with an output of 1000A can simultaneously achieve a stable output of 30A, the circuit design is extremely difficult, and the implementation difficulty and cost are very high.

[0006] Third, if the arc starting current is too small during arc starting, the wire and the workpiece are prone to adhesion during short circuit; if the current is too large, the short circuit melting is intense, forming a large explosion spatter, directly affecting the welding quality.

[0007] Therefore, this patent aims to provide a gas metal arc welding device and an arc starting method with a high arc starting success rate and small arc starting spatter. Summary of the Invention

[0008] The purpose of the present invention is to provide a gas metal arc welding device and an arc starting method to solve the problems raised in the above background art.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A gas metal arc welding equipment, comprising a welding torch, a welding power source and a shielding gas device respectively connected to the welding torch, wherein the welding torch is connected with a wire reel through a servo wire feeder, and the welding power source includes a main power source and an auxiliary power source.

[0011] Further, an arc maintaining control circuit is provided in the welding power source, and the arc maintaining control circuit includes an arc maintaining switch, a filtering circuit, a PI regulating circuit and a PWM conversion circuit.

[0012] Further, one end of the arc maintaining switch is connected to the G terminal of MOS transistor M1. The filtering circuit includes a sliding resistor WE1, a first resistor R1 and a first capacitor C1. The output end of the filtering circuit is connected to the non-inverting input terminal (i.e., the 3rd interface) of operational amplifier U2 in the operational amplifier circuit. The inverting input terminal (i.e., the 2nd interface) of operational amplifier U2 is connected to the 3rd interface of current feedback terminal J1 through a sixth resistor R6. The PI regulating circuit includes a fifth resistor R5, a seventh resistor R7 and a second capacitor C2. The fifth resistor R5 is connected in parallel between the inverting input terminal and the output terminal of operational amplifier U2. The seventh resistor R7 and the second capacitor C2 are connected in series and then connected in parallel between the inverting input terminal and the output terminal of operational amplifier U2. The output end of operational amplifier U2 is also connected to the 3rd interface of conversion chip U1 in the PWM conversion circuit through a second resistor R2. The 6th interface of conversion chip U1 is connected to the S pole of MOS transistor M1 and the 2nd interface of chip G1 through a third resistor R3 respectively. The 5th interface of conversion chip U1 and the D pole of MOS transistor M1 are both grounded. The 2nd interface of chip G1 is grounded through a fourth resistor R4.

[0013] Further, the arc maintaining control circuit is provided with feedback and acquisition of arc maintaining voltage V1 and arc maintaining current A1.

[0014] Further, the arc maintaining control circuit is provided with feedback and acquisition of main arc voltage V2 and main arc current A2.

[0015] An arc starting method for gas metal arc welding, adopting a dual power supply structure of an auxiliary power source and a main power source. The servo wire feeder feeds the wire to contact with the welding product. The auxiliary power source outputs an arc starting current. If the welding wire is retracted, the arc starting voltage breaks down and ionizes the gas, and a stable arc is formed and conducted. When the voltage and current reach the preset values, the arc starting is successful. After the arc starting is successful, the main power source outputs the welding current according to the program instruction for welding. If the welding wire is retracted, the current and voltage values are detected. If the set values are not reached, the arc starting this time is not successful, and the servo wire feeder performs a secondary arc starting action of feeding and retracting the wire again, thereby ensuring the success rate of arc starting.

[0016] Further, the arc starting current ≤ 30A.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The present invention adopts a dual-power supply structure of an auxiliary power supply and a main power supply. The auxiliary power supply is used to output the arc-starting current. In cooperation with the servo wire feeder, after the welding wire contacts the welded product, wire drawing and separation are performed to form a small and stable arc, which can achieve the effects of stable arc burning, no melting or non-exploding melting of the welding wire, no arc interruption, and a high arc-starting success rate. After the arc is stable, the main power supply outputs the welding current to perform the welding with normal settings. In this way, the welding arc-starting splash caused by the conventional large-current impact arc-starting method can be effectively avoided, the arc-starting success rate can be improved, and the welding quality can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the present invention;

[0020] Figure 2 is a circuit diagram of the arc-maintaining control circuit in the present invention;

[0021] Figure 3 is a signal schematic diagram of the present invention;

[0022] In the figure: 1 - welding power supply; 2 - welding torch; 3 - shielding gas device; 4 - servo wire feeder; 5 - wire reel; 6 - main power supply; 7 - auxiliary power supply.

[0023] The technical solutions of this patent will be further described in detail below in conjunction with specific embodiments.

[0024] Please refer to Figures 1-3 , a gas metal arc welding equipment, including a welding torch 2, a welding power supply 1 and a shielding gas device 3 respectively connected to the welding torch 2. The welding torch 2 is also connected to a wire reel 5 through a servo wire feeder 4. The servo wire feeder 4 can accurately control the wire feeding, wire drawing speed and distance. The welding power supply 1 includes a main power supply 6 and an auxiliary power supply 7. An independent high-precision small-current auxiliary power supply 7 is used as the arc-starting power supply. For welding with a welding wire diameter of less than 5 mm, the arc-starting current is less than 30 A.

[0025] The welding power source 1 is provided with a pilot arc control circuit, and the pilot arc control circuit includes a pilot arc switch, a filter circuit, a PI adjustment circuit, and a PWM conversion circuit. One end of the pilot arc switch is connected to the G terminal of the MOS tube M1. The filter circuit includes a sliding resistor WE1, a first resistor R1, and a first capacitor C1. The output end of the filter circuit is connected to the non-inverting input terminal, i.e., the 3rd interface, of the operational amplifier U2 in the operational amplifier circuit. The inverting input terminal, i.e., the 2nd interface, of the operational amplifier U2 is connected to the 3rd interface of the current feedback terminal J1 through the sixth resistor R6. The PI adjustment circuit includes a fifth resistor R5, a seventh resistor R7, and a second capacitor C2. The fifth resistor R5 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U2. The seventh resistor R7 and the second capacitor C2 are connected in series and then connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U2. The output end of the operational amplifier U2 is also connected to the 3rd interface of the conversion chip U1 in the PWM conversion circuit through the second resistor R2. The 6th interface of the conversion chip U1 is connected to the S pole of the MOS tube M1 and the 2nd interface of the chip G1 through the third resistor R3. The 5th interface of the conversion chip U1 and the D pole of the MOS tube M1 are both grounded. The 2nd interface of the chip G1 is grounded through the fourth resistor R4. The pilot arc control circuit is provided with feedback and acquisition of the pilot arc voltage V1 and the pilot arc current A1. The pilot arc control circuit is provided with feedback and acquisition of the main arc voltage V2 and the main arc current A2. This pilot arc control circuit can output a PWM waveform of 50KHZ. The circuit structure is simple, and it has a PI dynamic response speed of 300us. When the wire feeding distance of the servo wire feeder 4 exceeds the set distance and no relevant signal is detected or the relevant value is not reached, the next repeated arc ignition can be carried out. The repeated wire feeding and the contact discharge of the current can effectively break through the oxide film on the product. If the number of repeated arc ignitions exceeds the protection value, it will enter the overlimit protection state.

[0026] An arc ignition method for gas metal arc welding adopts a dual power source structure of an auxiliary power source 7 and a main power source 6. The servo wire feeder 4 feeds wire and contacts the welding product. The auxiliary power source 7 outputs an arc ignition current, and the arc ignition current ≤ 30A. If the welding wire is retracted, the arc ignition voltage breaks down the ionized gas and conducts to form a stable arc. When the voltage and current reach the preset values, the arc ignition is successful. After the arc ignition is successful, the main power source 6 outputs the welding current according to the program instruction for welding; if the welding wire is retracted, the current and voltage values are detected. If the set values are not reached, the arc ignition this time is not successful, and the servo wire feeder 4 performs a secondary arc ignition action of feeding wire and retracting wire again, thereby ensuring the success rate of arc ignition.

[0027] The present invention adopts a dual-power supply structure of an auxiliary power supply 7 and a main power supply 6. The auxiliary power supply 7 outputs a relatively small current, which cooperates with the wire drawing action of the welding wire to break through the gas ionization, form a small arc, and complete the arc starting. This small arc is not used to melt the welding wire, but simply to conduct the circuit, form an arc, and play a guiding role to assist the output of the large welding current of the subsequent main power supply 6. Moreover, the welding current is output according to the control waveform rhythm and is directly used to melt the welding wire, thus avoiding the explosion, cracking, and spattering caused by the contact of large current.

[0028] The above-described embodiments of the present invention do not constitute a limitation to the protection scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A metal arc welding device, comprising a welding gun (2) and a welding power source (1) and a shielding gas device (3) respectively connected to the welding gun (2), characterized in that: The welding gun (2) is connected to a wire reel (5) via a servo wire feeder (4), and the welding power source (1) comprises a main power source (6) and an auxiliary power source (7).

2. The gas metal arc welding equipment according to claim 1, characterized in that: The welding power source (1) is provided with an arc pilot control circuit, which comprises an arc pilot switch, a filter circuit, a PI adjustment circuit and a PWM conversion circuit.

3. The metal arc welding equipment according to claim 2, characterized in that: One end of the pilot arc switch is connected to the G end of the MOS tube M1, the filter circuit includes a sliding resistor WE1, a first resistor R1 and a first capacitor C1, the output end of the filter circuit is connected to the in-phase input end of the operational amplifier U2 in the operational amplifier circuit, that is, the interface No. 3, the inverting input end of the operational amplifier U2, that is, the interface No. 2 is connected to the interface No. 3 of the current feedback terminal J1 through the sixth resistor R6, the PI adjustment circuit includes a fifth resistor R5, a seventh resistor R7 and a second capacitor C2, the fifth resistor R5 is connected in parallel to the inverting input end and the output end of the operational amplifier U2, the seventh resistor R7 and the second capacitor C2 are connected in series and then connected in parallel to the inverting input end and the output end of the operational amplifier U2, the output end of the operational amplifier U2 is also connected to the interface No. 3 of the conversion chip U1 in the PWM conversion circuit through the second resistor R2, the interface No. 6 of the conversion chip U1 is respectively connected to the S pole of the MOS tube M1 and the interface No. 2 of the chip G1 through the third resistor R3, the interface No. 5 of the conversion chip U1 and the D pole of the MOS tube M1 are both grounded, and the interface No. 2 of the chip G1 is grounded through the fourth resistor R4.

4. The metal arc welding equipment according to claim 2 or 3, characterized in that: The arc pilot control circuit is provided with feedback and collection of the arc pilot voltage V1 and the arc pilot current A1.

5. The metal arc welding equipment according to claim 2 or 3, characterized in that: The pilot arc control circuit is provided with feedback and collection of the main arc voltage V2 and the main arc current A2.

6. An arc starting method for gas metal arc welding according to any one of claims 1 to 3, characterized in that: A dual power supply structure of an auxiliary power supply (7) and a main power supply (6) is adopted. The servo wire feeder (4) feeds the wire to contact the welding product. The auxiliary power supply 7 outputs an arc striking current. If the welding wire is retracted, the arc striking voltage breaks through the ionized gas, and conducts to form a stable arc. The voltage and current reach the preset values, that is, the arc striking is successful. After the arc striking is successful, the main power supply (6) outputs the welding current according to the program instruction to perform welding. If the welding wire is retracted, the current and voltage values ​​are detected and do not reach the set values, then the arc striking is unsuccessful this time. The servo wire feeder (4) performs the secondary arc striking action of feeding and drawing the wire again, thereby ensuring the success rate of arc striking.

7. The arc starting method of gas metal arc welding according to claim 6, characterized in that: The arc striking current is ≤30A.

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