Electrode breakdown monitoring and protecting device for plasma cutting machine

Abstract

An electrode breakdown monitoring and protecting device for a plasma cutting machine relates to the technical field of plasma cutting machines and is provided with a flow monitoring mechanism, an anti-splashing spectrum sensing mechanism and an operation control unit, the flow monitoring mechanism monitors water inlet flow and 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 monitors 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, the cutting gun can be stopped in time, damage to high-value parts such as the cutting gun body caused by untimely stopping is avoided, meanwhile, the service life of the hafnium wire of the electrode is utilized to the maximum extent, the waste phenomenon is avoided, and the service life of the plasma electrode can be prolonged by more than 20%.

Description

Technical Field

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

[0002] The cutting gun assembly of the CNC plasma cutting machine includes the cutting gun body, electrode, swirl ring, nozzle, protective cap, and 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 is generated between the electrode and the steel plate being cut, and its temperature can be as high as 15,000-30,000 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. The interior of the electrode is provided with a cavity, and there is high-speed flowing cooling circulating water in the cavity. The heat generated by the cavity is taken away by the circulating cooling system through a dedicated radiator, so that the electrode can maintain a cutting life of about 2 hours. If it is continued to be used at this time, the electrode will occasionally break down, 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 their inability 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 will be triggered to remind the operator to replace the new electrode. However, due to the influence of uncertain factors such as the material thickness of the cut material, the quality of the cutting gas, the flatness of the cutting platform, and the degree of slag, actual on-site measurements of the electrodes replaced using this method found that the electrode ablation depths varied greatly, with the average ablation depth of the electrode hafnium wire being only 62%, which seriously wastes the electrode life. Secondly, plasma cutting equipment has low-flow monitoring for circulating water. That is, when the return water flow after passing through the electrode falls below a threshold, the shutdown mechanism will be triggered, cutting off the plasma arc. However, if the water pump is in good condition, even if some coolant leaks after the electrode breaks down, the return water flow will be higher than the threshold in the few seconds when the fault such as the torch body burning out expands. Therefore, after actual analysis, this protection system is mainly used to protect against the circulating water flow falling below the threshold due to reasons such as aging of the water pump, and its protection ability against electrode breakdown is limited.

[0004] The above existing equipment and technologies cannot immediately shut down the machine 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 monitoring and protection device to solve this problem. Utility Model Content

[0005] The purpose of the utility model is to provide a plasma cutting machine electrode breakdown monitoring and protection device, which can realize automatic stop protection of the plasma cutting machine electrode breakdown, avoid damage to high-value components such as the cutting gun body, and improve the service life of the plasma electrode.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A plasma cutting machine electrode breakdown monitoring and protection device includes a flow monitoring mechanism, an anti-splash spectrum sensing mechanism and an operation and control unit. The flow monitoring mechanism monitors the inlet flow and return flow of the electrode cooling water and transmits an electrical signal to the operation and control unit. When the operation and control unit determines that the difference between the inlet flow and the return flow exceeds a threshold value, the operation and control unit outputs a stop signal to stop the plasma cutting machine. The anti-splash spectrum sensing mechanism monitors the arc color change when the electrode breaks down and transmits an electrical signal to the operation and control unit. When the operation and control unit determines that the spectrum changes, the operation and control unit outputs a stop signal to stop the plasma cutting machine.

[0008] The above-mentioned plasma cutting machine electrode breakdown monitoring and protection device, the flow monitoring 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 transmitted to the operation control unit.

[0009] The above-mentioned plasma cutting machine electrode breakdown monitoring and 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 faces the spectral sensor, and the left end faces the arc of the plasma cutting machine electrode. A compressed air inlet is provided on the anti-splash light tube. Compressed air enters from 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 transmitted to the operation control unit.

[0010] The above-mentioned plasma cutting machine electrode breakdown monitoring and protection device is provided with a flow difference over-limit alarm signal output terminal, a spectrum over-limit alarm signal output terminal, a flow and spectrum alarm mode switch, and an alarm reset input terminal on the operation control unit.

[0011] The utility model has the following advantages:

[0012] The utility model is provided with a flow monitoring mechanism, an anti-splash spectrum sensing mechanism and an operation control unit. The flow monitoring mechanism monitors the inlet flow and return flow of the electrode cooling water. If the electrode is ablated and broken down, part of the coolant leaks, and a difference will occur between the inlet flow and the return flow. 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 monitors the arc color change when the electrode is broken down. 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 to the splash during the cutting operation. The utility model realizes the precise monitoring of the electrode breakdown phenomenon. First, before the electrode is about to break down, the anti-splash spectrum sensing mechanism sends a signal to the operation control unit, which can stop the machine in time, avoiding 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 without causing waste, which can increase the service life of the plasma electrode by more than 20%. Secondly, if the anti-splash spectrum sensing mechanism fails or other unexpected situations occur, resulting in electrode ablation, the flow monitoring mechanism will also send a signal to ensure timely shutdown. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the utility model;

[0014] Figure 2 It is a schematic diagram of the electrode structure of the prior art;

[0015] 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. Water inlet flow sensor, 7. Return water flow sensor, 8. Spectral sensor, 9. Anti-splash light tube, 10. Compressed air inlet, 11. Flow difference over-limit alarm signal output terminal, 12. Operation control unit, 13. Spectral over-limit alarm signal output terminal, 14. Flow and spectrum alarm mode switch, 15. Alarm reset input terminal. DETAILED DESCRIPTION

[0016] The utility model is a plasma cutting machine electrode breakdown monitoring and protection device, such as Figure 1As shown, the copper electrode body 1 is provided with a cooling water return pipe 2 and a cooling water inlet pipe 3. A heat dissipation reservoir 5 is connected to the cooling water return pipe 2 and the cooling water inlet pipe 3, respectively. Cooling water enters the inner cavity of the copper electrode body 1 through the cooling water inlet pipe 3 and flows out through the cooling water return pipe 2. The cooling water removes the heat generated during cutting and dissipates it in the heat dissipation reservoir 5. A return water flow sensor 7 is installed on the cooling water return pipe 2 to monitor the return water flow, and an inlet water flow sensor 6 is installed on the cooling water inlet pipe 3 to monitor the inlet water flow. The electrical signals from the inlet water flow sensor 6 and the return water flow sensor 7 are transmitted to the calculation control unit 12. When the electrode is operating normally, the electrode inlet and return water flows are equal, and the flow difference is zero. When the plasma electrode breaks down, some coolant is lost through the breakdown point, and the electrode inlet water flow exceeds 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 calculation control unit 12 to determine whether the electrode has broken down. If the electrode breaks down, the operation control unit 12 will make a judgment and output a stop signal in time to stop the plasma cutting machine.

[0017] The utility model is a plasma cutting machine electrode breakdown monitoring and protection device, such as Figure 1 As shown, the spectral sensor 8 is aimed at the arc generated during plasma cutting through the anti-spatter light tube 9. When cutting steel plate, the plasma emits a bluish-white arc light. When the high-temperature resistant hafnium wire 4 at the front end of the electrode is completely ablated and begins to ablate the electrode copper body 1, a green arc light is emitted. When the hafnium wire 4 is completely ablated and begins to ablate the electrode copper body 1, the green arc light illuminates the spectral sensor 8, which then transmits an analog signal with a specific spectral intensity to the calculation and control unit 12. The wavelength of blue light is 400-450 nanometers and the frequency is 450-480 megahertz. The wavelength of green light is 490-560 nanometers and the frequency is 510-560 megahertz. When the green spectral signal is input, the calculation and control unit 12 determines that it exceeds the threshold and promptly outputs a stop signal to stop the plasma cutting machine.

[0018] In order to prevent dust and metal slag from splashing, an anti-splash light tube 9 is set 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.

[0019] The present invention provides a plasma cutting machine electrode breakdown monitoring and protection device, comprising a flow rate difference over-limit alarm signal output terminal 11, a spectrum over-limit alarm signal output terminal 13, a flow rate and spectrum alarm mode switch 14, and an alarm reset input terminal 15. When copper metal is being cut, the same green arc light as that emitted when an electrode breaks down is emitted, and the spectrum alarm mode needs to be turned off using the flow rate and spectrum alarm mode switch.

[0020] The flow difference over-limit alarm signal output terminal 11 and the spectrum over-limit alarm signal output terminal 13 output alarm signals to prompt the operator of the fault source.

[0021] The operator can input a reset signal through the alarm reset input terminal 15 to eliminate the alarm.

Claims

1. A plasma cutting machine electrode breakdown monitoring and protection device, characterized by: The invention comprises a flow monitoring mechanism, an anti-splash spectrum sensing mechanism and an operation control unit (12). The flow monitoring mechanism monitors the inlet flow rate and the return flow rate of the electrode cooling water and transmits an electrical signal to the operation control unit (12). When the operation control unit (12) determines that the difference between the inlet flow rate and the return flow rate exceeds a threshold value, the operation control unit (12) outputs a stop signal to stop the operation of the plasma cutting machine. The anti-splash spectrum sensing mechanism monitors the arc color change when the electrode breaks down and transmits an electrical signal to the operation control unit (12). When the operation control unit (12) determines that the spectrum changes, the operation control unit (12) outputs a stop signal to stop the operation of the plasma cutting machine.

2. The plasma cutting machine electrode breakdown monitoring and protection device according to claim 1, characterized in that: The flow monitoring 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 the electrical signals of the inlet flow sensor (6) and the return flow sensor (7) are transmitted to the operation control unit (12).

3. The plasma cutting machine electrode breakdown monitoring and protection device according to claim 1, characterized in that: The anti-splash spectrum sensing mechanism comprises a spectrum sensor (8) and an anti-splash light tube (9). The right end of the anti-splash light tube (9) faces the spectrum sensor (8), and the left end faces the arc of the plasma cutting machine electrode. 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 spectrum sensor (8) is transmitted to the operation control unit (12).

4. The plasma cutting machine electrode breakdown monitoring and protection device according to claim 1, characterized in that: The operation control unit (12) is provided with a flow difference over-limit alarm signal output terminal (11), a spectrum over-limit alarm signal output terminal (13), a flow and spectrum alarm mode switch (14), and an alarm reset input terminal (15).

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