Electrode breakdown automatic stop protection device of plasma cutting machine

Abstract

A plasma cutting machine electrode breakdown automatic stop protection device relates to the technical field of plasma cutting machines and is provided with a flow detection mechanism, an anti-splashing spectrum induction mechanism and an operation control unit, the flow detection mechanism detects the water inlet flow and the water return flow of electrode cooling water, and if an electrode is ablated and broken down, a difference value is generated between the water inlet flow and the water return flow; after the computing control unit makes a judgment, a stop signal is output in time, and the plasma cutting machine stops working; the anti-splashing spectrum sensing mechanism detects the arc light color change during electrode breakdown, and the operation control unit outputs a stopping signal when judging the spectrum change, so that the plasma cutting machine is stopped in time. Before the electrode is broken down, shutdown can be conducted in time, damage to high-value parts such as a cutting gun body caused by untimely shutdown is avoided, meanwhile, the service life of an electrode hafnium wire is utilized to the maximum extent, the waste phenomenon is avoided, and the service life of the plasma electrode can be prolonged by 20% or above.

Description

Technical Field

[0001] The invention relates to the technical field of plasma cutting machines, in particular to an electrode breakdown automatic stop protection device for a water-cooled plasma cutting machine. Background Art

[0002] The cutting gun assembly of the CNC plasma cutting machine includes a cutting gun body, an electrode, a swirl ring, a nozzle, a protective cap, and an outer protective cover. Figure 2 As shown, the electrode is provided with a copper electrode body 1, a cooling water return pipe 2, a cooling water inlet pipe 3, and a hafnium wire 4. During the cutting process, a high-temperature and high-speed plasma arc will be generated between the electrode and the steel plate being cut, and its temperature can be as high as 15000-30000 degrees Celsius. The electrode is made of hollow copper as a whole, and its contact point with the arc is inlaid with a high-temperature resistant hafnium wire 4, and the interior of the electrode is arranged as a cavity, and there is high-speed flowing cooling circulating water in the cavity. The heat generated by the circulating cooling system is mostly taken away by a special radiator, so that the electrode can maintain a cutting life of about 2 hours. If it continues to be used at this time, the electrode will be broken down from time to time, and the electrode nozzle will be burned at the least, and the cutting gun body and the cutting gun cable will be burned at the worst.

[0003] For a long time, the industry has used the following methods to prevent plasma electrodes from burning out due to failure to stop automatically after breakdown: First, set an alarm for the electrode working time. Since the electrode life is strongly related to the electrode operating time, based on long-term operating experience, the alarm value for the electrode operating time is set at a relatively safe value. When this value is exceeded, an automatic alarm is triggered to remind the operator to replace the new electrode. However, due to the influence of uncertain factors such as the thickness of the material being cut, the quality of the cutting gas, the flatness of the cutting platform, and the degree of slag, actual measurements on site showed that the electrodes replaced using this method had a large difference in electrode ablation depth, with the average ablation depth of the electrode hafnium wire being only 62%, which seriously wastes the electrode life. Secondly, the plasma cutting equipment has a low-flow monitoring system for circulating water. That is, when the return water flow after the electrode is lower than a threshold, the parking mechanism will be triggered to cut off the plasma arc. However, if the water pump is in good condition, even if some coolant leaks after the electrode is broken down, the return water flow will be higher than the threshold in a few seconds when the fault such as the burning of the cutting gun body is expanded. Therefore, after actual analysis, this protection system is mainly used to protect the circulating water flow below the threshold caused by the aging of the water pump, and its protection against electrode breakdown is limited.

[0004] The above existing equipment and technology cannot stop the machine immediately after the electrode hafnium wire is ablated, and cannot accurately monitor the electrode breakdown phenomenon. Therefore, the industry urgently needs a plasma cutting machine electrode breakdown automatic stop protection device to solve the problem. Summary of the invention

[0005] The object of the present invention is to provide a plasma cutting machine electrode breakdown automatic stop protection device, to achieve the plasma cutting machine electrode breakdown automatic stop protection, to avoid damage to high-value components such as the cutting gun body, and to increase the service life of the plasma electrode.

[0006] To achieve the above object, the present invention adopts the following technical solution: A plasma cutting machine electrode breakdown automatic stop protection device comprises a flow detection mechanism, an anti-splash spectrum sensing mechanism and an operation control unit. The flow detection mechanism detects the inlet flow and return flow of electrode cooling water, and transmits an electrical signal to the operation control unit. When the operation control unit determines that the difference between the inlet flow and the return flow exceeds a threshold value, the operation control unit outputs a stop signal to stop the plasma cutting machine. The anti-splash spectrum sensing mechanism detects the arc light color change when the electrode breaks down, and transmits the electrical signal to the operation control unit. When the operation control unit determines the spectrum change, the operation control unit outputs a stop signal to stop the plasma cutting machine.

[0007] The above-mentioned plasma cutting machine electrode breakdown automatic stop protection device, the flow detection mechanism includes a cooling water return pipe, a cooling water inlet pipe, a heat dissipation storage tank, an inlet flow sensor, and a return flow sensor. The return flow sensor is installed on the cooling water return pipe, and the inlet flow sensor is installed on the cooling water inlet pipe. The heat dissipation storage tank is respectively connected to the cooling water return pipe and the cooling water inlet pipe. The electrical signals of the inlet flow sensor and the return flow sensor are input into the operation control unit from the flow signal input end.

[0008] The above-mentioned plasma cutting machine electrode breakdown automatic stop protection device, the anti-splash spectral sensing mechanism includes a spectral sensor and an anti-splash light tube, the right end of the anti-splash light tube is facing the spectral sensor, and the left end is facing the arc of the plasma cutting machine electrode, and a compressed air inlet is provided on the anti-splash light tube. Compressed air enters through the compressed air inlet and is ejected at the left end of the anti-splash light tube. The electrical signal of the spectral sensor is input to the operation control unit from the spectral signal input end.

[0009] The above-mentioned plasma cutting machine electrode breakdown automatic stop protection device is provided with a flow and spectrum alarm mode switch and an alarm reset input terminal on the operation control unit.

[0010] The present invention has the following advantages: The present invention is provided with a flow detection mechanism, an anti-splash spectrum sensing mechanism and an operation control unit. The flow detection mechanism detects the inlet flow and return flow of the electrode cooling water. If the electrode is ablated and punctured, part of the coolant leaks, and the inlet flow and return flow will have a difference. After the operation control unit makes a judgment, it will output a stop signal in time to stop the plasma cutting machine; the anti-splash spectrum sensing mechanism detects the arc light color change when the electrode is punctured. When the operation control unit judges the spectrum change, it outputs a stop signal and stops the plasma cutting machine in time. The setting of the anti-splash light tube reduces the damage of the spectral sensor by splashes during the cutting operation. The present invention realizes the precise monitoring of the electrode breakdown phenomenon. Before the electrode is about to break down, the machine can be shut down in time to avoid damage to high-value parts such as the cutting gun body due to untimely shutdown. At the same time, the service life of the electrode hafnium wire is maximized, and no waste is caused, which can increase the service life of the plasma electrode by more than 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the present invention; Figure 2 It is a schematic diagram of the electrode structure of the prior art; The numbers in the figure represent: 1. Copper electrode body, 2. Cooling water return pipe, 3. Cooling water inlet pipe, 4. Hafnium wire, 5. Heat dissipation storage tank, 6. Inlet flow sensor, 7. Return flow sensor, 8. Spectral sensor, 9. Anti-splash light tube, 10. Compressed air inlet, 11. Stop signal output terminal, 12. Flow difference over-limit alarm signal output terminal, 13. Spectral over-limit alarm signal output terminal, 14. Flow and spectrum alarm mode switch, 15. Flow signal input terminal, 16. Spectral signal input terminal, 17. Alarm reset input terminal, 18. Operation control unit. DETAILED DESCRIPTION

[0012] The present invention provides a plasma cutting machine electrode breakdown automatic stop protection device, such as Figure 1As shown, a cooling water return pipe 2 and a cooling water inlet pipe 3 are provided on the copper electrode body 1, and a heat dissipation storage tank 5 is connected to the cooling water return pipe 2 and the cooling water inlet pipe 3 respectively. The cooling water enters the inner cavity of the copper electrode body 1 from the cooling water inlet pipe 3 and flows out from the cooling water return pipe 2. The cooling water takes away the heat generated during cutting and dissipates heat in the heat dissipation storage tank 5. The return water flow sensor 7 is installed on the cooling water return pipe 2 to detect the return water flow. The inlet water flow sensor 6 is installed on the cooling water inlet pipe 3 to detect the inlet water flow. The electrical signals of the inlet water flow sensor 6 and the return water flow sensor 7 are input to the operation control unit 18 from the flow signal input terminal 15. When the electrode is in normal operation, the electrode inlet and return water flows are the same, and the flow difference is zero. When the plasma electrode is broken down, part of the coolant is lost through the breakdown, and the electrode inlet water flow is greater than the return water flow. The flow signals output by the inlet water flow sensor 6 and the return water flow sensor 7 are amplified and compared by the operation control unit 18 to determine whether the electrode is broken down. If the electrode breaks down, the operation control unit 18 will make a judgment and output a stop signal at the stop signal output terminal 11 in time to stop the plasma cutting machine.

[0013] The present invention provides a plasma cutting machine electrode breakdown automatic stop protection device, such as Figure 1 As shown, the spectrum sensor 8 is aimed at the arc generated during plasma cutting through the anti-splash light tube 9. When cutting the steel plate, the plasma emits a blue-white arc. When the high-temperature resistant hafnium wire 4 at the front end of the electrode is completely burned and begins to burn the electrode copper body 1, a green arc is emitted. When the electrode hafnium wire 4 is completely burned and begins to burn the electrode copper body 1, the emitted green arc irradiates the spectrum sensor 8. The spectrum sensor 8 emits a specific spectrum intensity analog signal which is input to the operation control unit 18 through the spectrum signal input terminal 16. The wavelength range of blue light is 400-450 nanometers and the frequency is 450-480 megahertz. The wavelength range of green light is 490-560 nanometers and the frequency is 510-560 megahertz. When the green spectrum signal is input, the operation control unit 18 determines that it exceeds the threshold value and promptly outputs a stop signal at the stop signal output terminal 11 to stop the plasma cutting machine.

[0014] In order to prevent dust and metal slag splashing, an anti-splash light tube 9 is arranged between the spectrum sensor 8 and the cutting arc, and high-pressure gas is blown into the anti-splash light tube 9 from the compressed air inlet 10 using high-pressure gas.

[0015] The present invention provides a plasma cutting machine electrode breakdown automatic stop protection device, which is provided with a flow difference over-limit alarm signal output terminal 12, a spectrum over-limit alarm signal output terminal 13, a flow and spectrum alarm mode switch 14, and an alarm reset input terminal 17. When copper metal needs to be cut, since the same green arc light as when the electrode breaks down is emitted, the spectrum alarm mode needs to be turned off through the flow and spectrum alarm mode switch 14.

[0016] The flow difference over-limit alarm signal output terminal 12 and the spectrum over-limit alarm signal output terminal 13 output alarm signals to prompt the operator of the source of the fault.

[0017] The operator can input a reset signal through the alarm reset input terminal 17 to eliminate the alarm.

Claims

1. A plasma cutting machine electrode breakdown automatic stop protection device, characterized in that: The invention comprises a flow detection mechanism, an anti-splash spectrum sensing mechanism and an operation control unit (18), wherein the flow detection mechanism detects the inlet flow rate and the return flow rate of the electrode cooling water and transmits an electrical signal to the operation control unit (18), and when the operation control unit (18) determines that the difference between the inlet flow rate and the return flow rate exceeds a threshold value, it outputs a stop signal to stop the operation of the plasma cutting machine; and the anti-splash spectrum sensing mechanism detects the change in arc color when the electrode is broken down and transmits an electrical signal to the operation control unit (18), and when the operation control unit (18) determines that the spectrum changes, it outputs a stop signal to stop the operation of the plasma cutting machine.

2. The electrode breakdown automatic stop protection device for a plasma cutting machine according to claim 1, characterized in that: The flow detection mechanism comprises a cooling water return pipe (2), a cooling water inlet pipe (3), a heat dissipation storage tank (5), an inlet flow sensor (6), and a return flow sensor (7); the return flow sensor (7) is mounted on the cooling water return pipe (2); the inlet flow sensor (6) is mounted on the cooling water inlet pipe (3); the heat dissipation storage tank (5) is connected to the cooling water return pipe (2) and the cooling water inlet pipe (3), respectively; and electrical signals of the inlet flow sensor (6) and the return flow sensor (7) are input from a flow signal input terminal (15) to an operation control unit (18).

3. The electrode breakdown automatic stop protection device for a plasma cutting machine according to claim 1, characterized in that: The anti-splash spectral sensing mechanism comprises a spectral sensor (8) and an anti-splash light tube (9). The right end of the anti-splash light tube (9) faces the spectral sensor (8), and the left end faces the arc of the electrode of the plasma cutting machine. A compressed air inlet (10) is provided on the anti-splash light tube (9). Compressed air enters through the compressed air inlet (10) and is ejected at the left end of the anti-splash light tube (9). The electrical signal of the spectral sensor (8) is input into the operation control unit (18) from the spectral signal input end (16).

4. The electrode breakdown automatic stop protection device for a plasma cutting machine according to claim 1, characterized in that: A flow rate and spectrum alarm mode switch (14) and an alarm reset input terminal (17) are provided on the operation control unit (18).

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