Energy-saving gas shielded welding control circuit

Abstract

A gas-saving gas shielded welding control circuit includes a rectifier power supply circuit that outputs DC power to a full-bridge frequency converter circuit. A main controller drives the full-bridge frequency converter circuit via a frequency converter control module. The full-bridge frequency converter circuit outputs frequency-converted AC power to an AC output circuit, which outputs alternating current. The AC output circuit is characterized by being further connected to an alternating counting control circuit. The output terminal of this alternating counting control circuit is connected to a gas path control valve (located on the gas supply line of the welding machine's shielding gas gun). Its advantages are: by combining the welding machine's existing frequency control technology with low-cost modifications, the supply of shielding gas can be rationally controlled according to actual working conditions, avoiding excessive gas waste.

Description

Technical Field

[0001] This invention relates to the field of gas shielded welding technology, and in particular to a gas-saving gas shielded welding control circuit. Background Technology

[0002] Gas shielded welding utilizes gas as a protective medium. It includes tungsten inert gas (TIG) welding and gas metal arc welding (GMAW). TIG welding was first developed in the aircraft manufacturing industry to meet the welding needs of aluminum alloys, magnesium alloys, and stainless steel. Subsequently, to overcome the shortcomings of TIG welding, such as its difficulty in welding thick workpieces and low welding productivity, GMAW entered practical application in the late 1940s after a certain understanding of droplet transfer patterns. Carbon dioxide gas shielded welding technology overcame the high cost of TIG welding, enabling its widespread application in welding common steels such as carbon steel and low-alloy steel. Later, many other gas shielded welding methods emerged, including oxidizing mixed gas shielded welding, flux-cored wire gas shielded welding, pulsed TIG welding, and gas-electric vertical welding. Gas shielded welding, with its high efficiency and energy saving, has been widely adopted in many industrial sectors such as aviation, aerospace, machinery manufacturing, shipbuilding, and vehicle manufacturing. With the improvement of the automation level of welding equipment, the use of new arc welding power sources, and the promotion and application of electronic technology and intelligent control technology, the welding quality, welding productivity and stability of gas shielded welding will be significantly improved, and mixed gas shielded welding will achieve greater development.

[0003] When using a pulsed power supply, welding with a low-frequency pulsed current of 0.5–5 Hz can reduce the heat input to the workpiece, facilitate control of weld cooling and crystallization, and control of weld penetration. This is suitable for welding thin-walled components, suspended all-position welding, and root pass welding of thick-walled structures. Using a high-frequency pulsed current of 20 kHz can make the arc straight and stable, refine the weld metal grains, and increase the welding speed.

[0004] However, the existing technology still has the following drawbacks: throughout the entire gas welding process, the shielding gas is supplied in excess of demand, and the supply of shielding gas is not reasonably controlled according to the actual working conditions, resulting in serious waste. Summary of the Invention

[0005] The purpose of this invention is to provide a gas-saving gas shielded welding control circuit that can reasonably control the supply of shielding gas according to actual working conditions, avoiding excessive gas waste.

[0006] The gas-saving gas shielded welding control circuit includes a rectifier power supply circuit that outputs DC power to a full-bridge frequency converter circuit. The main controller drives the full-bridge frequency converter circuit via a frequency converter control module. The full-bridge frequency converter circuit outputs frequency-converted AC power to an AC output circuit, which outputs alternating current. The key feature is that the AC output circuit is also connected to an alternating counting control circuit. The output terminal of the alternating counting control circuit is connected to a gas path control valve, which is located on the gas supply line of the welding machine's shielded gas gun.

[0007] When welding with a low-frequency pulse current of 0.5–5 Hz, the welding power is often directly proportional to the frequency, and the gas demand is also directly proportional. Therefore, by building a circuit to control the gas supply using frequency and matching it to the welding power, gas is saved and costs are reduced.

[0008] The alternating counting control circuit includes an induction coil Ls, which senses the AC output circuit and outputs induced pulses to the alternating comparison circuit. The alternating comparison circuit extracts valid induced pulses and sends them to the counter U2. After counting the induced pulses, the counter U2 issues a control command to the gas path control valve.

[0009] The induction coil Ls is physically isolated from the power supply circuit. Simultaneously, it acquires the number of valid induction pulses, which are then counted by counter U2. After counter U2 accumulates the count, it proportionally reduces the number of control command pulses to meet the effective operating frequency requirements of the pneumatic control valve.

[0010] The full-bridge inverter circuit is a full-bridge circuit composed of four switching transistors, and the gates of the four switching transistors are respectively connected to the four control terminals of the inverter control module.

[0011] The two AC output terminals of the full-bridge inverter circuit are connected to the AC output circuit to output a pulse current of 0.5 to 5 Hz.

[0012] By leveraging the welding machine's proprietary AC-DC-AC frequency conversion control technology, the pulse frequency is made controllable at its source, thus meeting the need for low-cost retrofitting.

[0013] The AC output circuit includes a transformer TR1. The two ends of the AC input winding of the transformer TR1 are connected to the full-bridge frequency converter circuit. An induction coil Ls is set next to one output end of the AC output winding of the transformer TR1. A resistor R1 is connected in series between the two ends of the induction coil Ls. One end of the induction coil Ls is grounded. The other end of the induction coil Ls is connected in series with a diode D2 and a current-limiting resistor R2 and then connected to the positive input end of the optocoupler U1. The negative input end of the optocoupler U1 is grounded. The negative output end of the optocoupler U1 is grounded. The positive output end is connected in series with a resistor R3 and then connected to a high level. The positive output end is connected in series with a resistor R4 and then connected to the input end of the counter U2.

[0014] The output terminal of the counter U2 is connected to the base of the transistor Q5. The emitter of the transistor Q5 is grounded. The collector is connected in series with the winding of the relay J, and then in series with the resistor R5 connected to the positive power supply. The normally open switch of the relay J is connected in series in the power supply circuit of the pneumatic control valve.

[0015] The optocoupler U1 provides isolation, while the transistor Q5 and relay J provide combined driving, further ensuring the safe use of the circuit.

[0016] The first output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8a, and the second output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8b. The cathodes of diodes D8a and D8b are connected in parallel and connected to the front end of inductor L1. The rear end of inductor L1 is the positive power supply of the load, which is connected to the positive power supply terminal of wire feeder and welding torch.

[0017] On the AC output winding of the transformer TR1, a load negative power supply is provided at the midpoint between the first output terminal and the second output terminal. This load negative power supply is connected to the negative power supply terminals of the wire feeder and the welding torch.

[0018] The positive power supply of the load is connected to the positive terminal of the electrolytic capacitor C8, and the negative terminal of the electrolytic capacitor C8 is grounded.

[0019] The negative power supply of the load is connected to the negative terminal of the electrolytic capacitor C9, and the positive terminal of the electrolytic capacitor C9 is grounded.

[0020] The induction coil Ls is installed near the front end of the inductor L1.

[0021] The anode of the diode D8a is connected to the positive terminal of the electrolytic capacitor C5 after being connected in series with resistor R8. The negative terminal of the electrolytic capacitor C5 is connected to the cathode of the diode D8a.

[0022] The anode of the diode D8b is connected to the positive terminal of the electrolytic capacitor C6 after being connected in series with resistor R9, and the negative terminal of the electrolytic capacitor C6 is connected to the cathode of the diode D8b.

[0023] The induction coil Ls is arranged between the resistor R8 and the electrolytic capacitor C5;

[0024] Alternatively, the induction coil Ls can be arranged between the resistor R9 and the electrolytic capacitor C6.

[0025] Beneficial effects: It provides a gas-saving gas shielded welding control circuit. Combined with the welding machine's own frequency control technology, it can be modified at low cost to reasonably control the supply of shielding gas according to the actual working conditions and avoid excessive gas waste. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the variable frequency drive principle of a welding machine;

[0027] Figure 2 It is an alternating counting control circuit;

[0028] Figure 3 This is a schematic diagram of the pneumatic control valve. Detailed Implementation

[0029] The specific embodiments and working principles of the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Example 1, as Figure 1 As shown, the gas-saving gas shielded welding control circuit includes a rectifier power supply circuit that outputs DC power to a full-bridge frequency converter circuit. The main controller drives the full-bridge frequency converter circuit via a frequency converter control module. The full-bridge frequency converter circuit outputs frequency-converted AC power to an AC output circuit, which outputs alternating current. The AC output circuit is characterized by being further connected to an alternating counting control circuit. The output terminal of the alternating counting control circuit is connected to a gas path control valve 1, which is located on the gas supply pipeline of the welding machine's shielded gas gun.

[0031] like Figure 2 As shown, the alternating counting control circuit includes an induction coil Ls, which senses the AC output circuit and outputs induced pulses to the alternating comparison circuit. The alternating comparison circuit extracts the valid induced pulses and sends them to the counter U2. After counting the induced pulses, the counter U2 issues a control command to the gas control valve 1.

[0032] like Figure 1 As shown, the full-bridge inverter circuit is a full-bridge circuit composed of four switching transistors, and the gates of the four switching transistors are respectively connected to the four control terminals of the inverter control module.

[0033] The two AC output terminals of the full-bridge inverter circuit are connected to the AC output circuit to output a pulse current of 0.5 to 5 Hz.

[0034] The AC output circuit includes a transformer TR1. The two ends of the AC input winding of the transformer TR1 are connected to the full-bridge frequency converter circuit. An induction coil Ls is set next to one output end of the AC output winding of the transformer TR1. A resistor R1 is connected in series between the two ends of the induction coil Ls. One end of the induction coil Ls is grounded. The other end of the induction coil Ls is connected in series with a diode D2 and a current-limiting resistor R2 and then connected to the positive input end of the optocoupler U1. The negative input end of the optocoupler U1 is grounded. The negative output end of the optocoupler U1 is grounded. The positive output end is connected in series with a resistor R3 and then connected to a high level. The positive output end is connected in series with a resistor R4 and then connected to the input end of the counter U2.

[0035] like Figure 2 , 3As shown, the output terminal of the counter U2 is connected to the base of the transistor Q5. The emitter of the transistor Q5 is grounded, and the collector is connected in series with the winding of the relay J, and then in series with the resistor R5 connected to the positive power supply. The normally open switch of the relay J is connected in series in the power supply circuit of the pneumatic control valve 1.

[0036] The first output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8a, and the second output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8b. The cathodes of diodes D8a and D8b are connected in parallel and connected to the front end of inductor L1. The rear end of inductor L1 is the positive power supply of the load, which is connected to the positive power supply terminal of wire feeder and welding torch.

[0037] On the AC output winding of the transformer TR1, a load negative power supply is provided at the midpoint between the first output terminal and the second output terminal. This load negative power supply is connected to the negative power supply terminals of the wire feeder and the welding torch.

[0038] The positive power supply of the load is connected to the positive terminal of the electrolytic capacitor C8, and the negative terminal of the electrolytic capacitor C8 is grounded.

[0039] The negative power supply of the load is connected to the negative terminal of the electrolytic capacitor C9, and the positive terminal of the electrolytic capacitor C9 is grounded.

[0040] The induction coil Ls is installed near the front end of the inductor L1.

[0041] The anode of the diode D8a is connected to the positive terminal of the electrolytic capacitor C5 after being connected in series with resistor R8. The negative terminal of the electrolytic capacitor C5 is connected to the cathode of the diode D8a.

[0042] The anode of the diode D8b is connected to the positive terminal of the electrolytic capacitor C6 after being connected in series with resistor R9, and the negative terminal of the electrolytic capacitor C6 is connected to the cathode of the diode D8b.

[0043] Examples 2 and 3 have the same structure as Example 1, the difference being the installation position of the induction coil Ls:

[0044] In Example 2, the induction coil Ls is arranged between the resistor R8 and the electrolytic capacitor C5;

[0045] In Example 3, the induction coil Ls is arranged between the resistor R9 and the electrolytic capacitor C6.

Claims

1. A gas-saving gas shielded welding control circuit, comprising a rectifier power supply circuit that outputs DC power to a full-bridge frequency converter circuit, a main controller driving the full-bridge frequency converter circuit via a frequency converter control module, the full-bridge frequency converter circuit outputting frequency-converted AC power to an AC output circuit, and the AC output circuit outputting alternating current, characterized in that... The AC output circuit is also connected to an alternating counting control circuit, the output of which is connected to a gas path control valve (1), which is arranged on the gas supply line of the welding machine protective gas gun. The alternating counting control circuit includes an induction coil Ls, which senses the AC output circuit and outputs induced pulses to the alternating comparison circuit. The alternating comparison circuit extracts the valid induced pulses and sends them to the counter U2. After counting the induced pulses, the counter U2 sends a control command to the gas control valve (1). The full-bridge inverter circuit is a full-bridge circuit composed of four switching transistors, and the gates of the four switching transistors are respectively connected to the four control terminals of the inverter control module. The two AC output terminals of the full-bridge inverter circuit are connected to the AC output circuit to output a pulse current of 0.5 to 5 Hz.

2. The gas-saving gas shielded welding control circuit according to claim 1, characterized in that, The AC output circuit includes a transformer TR1. The two ends of the AC input winding of the transformer TR1 are connected to the full-bridge frequency converter circuit. An induction coil Ls is set next to one output end of the AC output winding of the transformer TR1. A resistor R1 is connected in series between the two ends of the induction coil Ls. One end of the induction coil Ls is grounded. The other end of the induction coil Ls is connected in series with a diode D2 and a current-limiting resistor R2 and then connected to the positive input end of the optocoupler U1. The negative input end of the optocoupler U1 is grounded. The negative output end of the optocoupler U1 is grounded. The positive output end is connected in series with a resistor R3 and then connected to a high level. The positive output end is connected in series with a resistor R4 and then connected to the input end of the counter U2.

3. The gas-saving gas shielded welding control circuit according to claim 2, characterized in that, The output terminal of the counter U2 is connected to the base of the transistor Q5. The emitter of the transistor Q5 is grounded, and the collector is connected in series with the winding of the relay J, and then in series with the resistor R5 connected to the positive power supply. The normally open switch of the relay J is connected in series in the power supply circuit of the pneumatic control valve (1).

4. The gas-saving gas shielded welding control circuit according to claim 2, characterized in that, The first output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8a, and the second output terminal of the AC output winding of transformer TR1 is connected to the anode of diode D8b. The cathodes of diodes D8a and D8b are connected in parallel and connected to the front end of inductor L1. The rear end of inductor L1 is the positive power supply of the load, which is connected to the positive power supply terminal of wire feeder and welding torch. On the AC output winding of the transformer TR1, a load negative power supply is provided at the midpoint between the first output terminal and the second output terminal. This load negative power supply is connected to the negative power supply terminals of the wire feeder and the welding torch.

5. The gas-saving gas shielded welding control circuit according to claim 4, characterized in that, The positive power supply of the load is connected to the positive terminal of the electrolytic capacitor C8, and the negative terminal of the electrolytic capacitor C8 is grounded. The negative power supply of the load is connected to the negative terminal of the electrolytic capacitor C9, and the positive terminal of the electrolytic capacitor C9 is grounded.

6. The gas-saving gas shielded welding control circuit according to claim 4, characterized in that, The induction coil Ls is installed near the front end of the inductor L1.

7. The gas-saving gas shielded welding control circuit according to claim 4, characterized in that, The anode of the diode D8a is connected to the positive terminal of the electrolytic capacitor C5 after being connected in series with resistor R8. The negative terminal of the electrolytic capacitor C5 is connected to the cathode of the diode D8a. The anode of the diode D8b is connected to the positive terminal of the electrolytic capacitor C6 after being connected in series with resistor R9, and the negative terminal of the electrolytic capacitor C6 is connected to the cathode of the diode D8b.

8. The gas-saving gas shielded welding control circuit according to claim 7, characterized in that, The induction coil Ls is arranged between the resistor R8 and the electrolytic capacitor C5; Alternatively, the induction coil Ls can be arranged between the resistor R9 and the electrolytic capacitor C6.

Images