CN108372349B - Electric shock protection device and method for plasma cutting machine - Google Patents
Electric shock protection device and method for plasma cutting machine Download PDFInfo
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- CN108372349B CN108372349B CN201810186900.8A CN201810186900A CN108372349B CN 108372349 B CN108372349 B CN 108372349B CN 201810186900 A CN201810186900 A CN 201810186900A CN 108372349 B CN108372349 B CN 108372349B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K10/00—Welding or cutting by means of a plasma
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K37/00—Auxiliary devices or processes, not specially adapted to a procedure covered by only one of the preceding main groups
- B23K37/006—Safety devices
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Abstract
The invention discloses an electric shock protection device for a plasma cutting machine, which comprises: a detection circuit that detects whether a loop is formed between the electrode and the nozzle and outputs a detection signal; and the control unit receives the detection signal and starts the cutting machine or sends out an alarm signal according to the detection signal, wherein the alarm signal is used for cutting off the working current of the plasma cutting machine. The invention also discloses an electric shock protection method.
Description
Technical Field
The invention relates to the technical field of plasma cutting machines, in particular to an electric shock protection device for a plasma cutting machine.
Background
Plasma arc cutting is a machining method that uses the heat of a high-temperature plasma arc to locally melt (evaporate) metal at a workpiece kerf and uses the momentum of the high-speed plasma to remove the molten metal to form the kerf.
Plasma is a highly ionized gas heated to extremely high temperatures that transfers arc power to the workpiece, and the high heat melts and blows the workpiece away, creating an operational state of plasma arc cutting. After compressed air enters the cutting torch, two paths of compressed air are distributed by the air chamber, so that plasma gas and auxiliary gas are formed. The plasma gas arc acts to melt the metal, while the assist gas cools the various components of the torch and blows the melted metal away. The plasma cutting is matched with different working gases, so that various metals which are difficult to cut by oxygen cutting can be cut, and the cutting effect is better particularly for nonferrous metals (stainless steel, aluminum, copper, titanium and nickel); the main advantages are that when cutting metal with small thickness, the plasma cutting speed is high, especially when cutting common carbon steel sheet, the speed can reach 5-6 times of the oxygen cutting method, the cutting surface is smooth, the thermal deformation is small, and the heat affected zone is less.
Compared with the traditional cutting mode, the plasma cutting has the advantages of high efficiency, high precision, high stability and the like, and is especially suitable for mass production and processing and high-precision cutting requirements. In addition, from the cost perspective, the relative cost of plasma cutting is more economical due to the removal of the cost of cutting fuel gas, and the control of the processing cost is more obvious when the plasma cutting is particularly applied to mass processing production. The plasma cutting machine is widely applied to various industries such as automobiles, locomotives, pressure vessels, chemical machinery, nuclear industry, general machinery, engineering machinery, steel structures, ships and the like.
The ion cutting machine has the advantages of more concentrated plasma arc energy, higher temperature, higher cutting speed and small deformation, and can also cut stainless steel, aluminum and other materials.
The cutting machine uses plasma arc, the plasma arc is generated by the combined action of voltage, air pressure and magnetic field, so that the output of the cutting machine needs to have higher voltage (generally 100-600V) in order to randomly strike and prevent the plasma arc from being extinguished. Compared with the traditional cutting method, the output voltage is 2-5 times that of the traditional method, so that the danger of the output end is obviously improved. In particular to the aspect of personal safety, the danger of an output end is improved, and the operator of the cutting machine has larger electric shock danger, so that the method for preventing the electric shock of the plasma cutting machine is provided.
The prior art needs an electric shock protection device for a plasma cutting machine, which protects the life and health safety of operators of the cutting machine.
Disclosure of Invention
In view of the above, the present invention provides an anti-electric shock protection device and method for a plasma cutting machine, which can effectively detect whether a nozzle and an electrode are effectively installed, thereby achieving the purpose of anti-electric shock.
In order to achieve the above object, the present invention discloses an electric shock protection device for a plasma cutting machine, comprising: a detection circuit that detects whether a loop is formed between the electrode and the nozzle and outputs a detection signal; and the control unit receives the detection signal and starts the cutting machine or sends out an alarm signal according to the detection signal, wherein the alarm signal is used for cutting off the working current of the plasma cutting machine.
Further, a first detection end of the detection circuit is connected with the electrode, and a second detection end of the detection circuit is connected with the nozzle.
Further, the first detecting terminal is used for detecting Vout-, and the second detecting terminal is used for detecting vout+1, and when Vout- =vout+1, a loop is formed between the electrode and the nozzle.
Further, the detection circuit comprises a power supply and a detection signal output unit, wherein the power supply unit supplies power to the detection circuit, and the detection signal output unit is used for outputting the detection signal according to whether a loop is formed between the electrode and the nozzle.
Furthermore, the power supply unit is an isolated power supply, and the signal output unit is an optocoupler.
Furthermore, the detection circuit further comprises resistors R31 and R34, capacitors C51 and C52 and diodes D19 and D999, wherein one end of the resistor R31 is connected with an electrode, the other end of the resistor R31 is connected with an isolated power supply, one end of the resistor R31 is connected with the anode of the diode D19, and the other end of the resistor R31 is connected with the cathode of an input diode of the optocoupler; one end of the capacitor C51 is connected with the isolation power supply and the resistor R34, and the other end of the capacitor C is connected with the isolation power supply, the cathode of the diode D999 and the anode of the input diode of the optocoupler; the capacitor C52 is connected to the output side of the optocoupler, the cathode of the diode D19 is connected to the nozzle lead-out wire, and the anode is connected to the resistor R31.
Further, the voltage of the isolated power supply is 12V.
Further, the detecting signal is a voltage signal, when the voltage signal is 5V, the cutting machine is started, and when the voltage signal is 0V, the alarming signal is sent out.
Further, the detection circuit is also connected with the arc turning circuit.
The invention also discloses an electric shock protection method for the plasma cutting machine, which comprises the following steps: step one: detecting whether a loop is formed between the electrode and the nozzle and outputting a detection signal; step two: starting the cutting machine or cutting off the working current of the cutting machine according to the detection signal.
Compared with the prior art, the electric shock protection device and the method for the plasma cutting machine can detect whether the nozzle and the electrode are effectively installed, so that the purpose of electric shock protection is achieved. The detection circuit has simple structure, saves cost, occupies small actual space, does not need to additionally increase operation steps, and is convenient and stable to use.
On the other hand, the electric shock protection device and the method provided by the invention can detect whether the nozzle and the electrode are effectively installed or not at the same time, and have short time and quick response.
Drawings
The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:
FIG. 1 is a block diagram of the hardware of the shock protection device for a plasma cutter according to the present invention;
FIG. 2 is a schematic diagram of an electric shock protection device for a plasma cutter according to the present invention;
fig. 3 is a schematic diagram of the method for preventing electric shock according to the present invention.
Detailed Description
In the working process of the plasma cutting machine, the workpiece and the electrode are respectively connected with the positive electrode and the negative electrode of the output of the cutting machine, so that an electric arc is formed between the workpiece and the electrode. The arc is compressed by the nozzle, thereby emitting an arc with high temperature and high energy density. Wherein, the electrode mainly plays roles of conducting current and igniting electric arc; the nozzle plays a role of compressing the arc, and emits the arc with high temperature and high energy density. The workpiece is connected with the output positive electrode of the cutting machine, and the electrode is connected with the output negative electrode of the cutting machine, so that an electric arc is formed between the electrode and the workpiece, and the purpose of cutting the workpiece is achieved. When the plasma cutting machine works, if the nozzle and the electrode are not installed or are not installed, the external circuit is equivalent to open circuit. Because the open circuit voltage is very high (above 300V), the operator of the cutting machine is at risk of electric shock, and thus needs to be protected against electric shock. The invention provides an electric shock protection device and method for a plasma cutting machine, which can detect whether a nozzle and an electrode are effectively installed, increase a power supply between the nozzle and the electrode, judge whether a loop is formed between the nozzle and the electrode in a mode of detecting whether the voltages of the nozzle and the electrode are equal, and start the cutting machine or cut off a given circuit according to a detection result so as to achieve the purpose of electric shock protection.
In order to make the objects, advantages and features of the present invention more apparent, the following more particular description of the anti-shock device and method of the present invention will be presented in conjunction with the accompanying figures 1-3. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
As used in this specification, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
Fig. 1 is a block diagram showing the hardware principle of the electric shock protection device for the plasma cutting machine according to the present invention. As shown in fig. 1, the cutter comprises an electrode 1, a nozzle 2, a cutter circuit (not shown in the figure), a detection circuit 10, a control unit 20 and an alarm signal 30. The workpiece 3 and the electrode 1 are connected to the positive and negative poles of the cutter circuit, respectively, so that an arc is formed between the workpiece and the electrode. The electrode 1 is connected to a negative electrode lead of the detection circuit 10, and the nozzle 2 is connected to a positive electrode lead of the detection circuit 10. When the cutting machine works, if the nozzle and the electrode are not installed, the external circuit is equivalent to an open circuit, and the open circuit voltage is very high (more than 300V), so that the operator of the cutting machine has the danger of electric shock, and the operator needs to be protected against electric shock. Before striking an arc, it is necessary to detect whether the electrode and the nozzle of the cutter are both installed, so that the outgoing line OUT-is from the electrode and the outgoing line out+1 is from the nozzle. At this time, if the nozzle and the electrode are both installed, which corresponds to VOUT- =vout+1, a loop is formed between the positive lead and the negative lead of the detection circuit 10, the detection circuit 10 sends a detection signal to the control unit 20, the control unit 20 receives the detection signal, and starts the cutter or sends an alarm signal 30 according to the detection signal; the alarm signal is used for cutting off the working current of the plasma cutting machine.
Fig. 2 is a schematic circuit diagram of an electric shock protection device for a plasma cutter according to the present invention. As shown in fig. 2, the detection circuit includes resistors R31, R34, capacitors C51, C52, an optocoupler U8, an isolated power supply 1515, diodes D19, D999, and a CPU. One end of the resistor R34 is connected with the electrode outgoing line, and the other end is connected with the pin5 of the 1515 isolated power supply; one end of the resistor R31 is connected with the anode of the D19, and the other end of the resistor R is connected with the cathode of the input diode of the optocoupler; one end of the capacitor C51 is connected with the pin5 and R34 of the isolation power supply 1515, and the other end is connected with the cathodes of the pin7 and D999 of the isolation power supply 1515 and the anode of the input diode of the optocoupler; the capacitor C52 is connected with the output side of the optocoupler and the CPU; the cathode of the diode D19 is connected with a nozzle outgoing line, and the anode is connected with a resistor R31; the diode D999 is reversely connected with the light emitting diode at the input side of the optocoupler. Wherein an isolated power supply 1515 is used to power the electrode and nozzle mounting detection circuitry.
The nozzle outgoing line OUT+1 and the electrode outgoing line OUT-are simultaneously connected with an arc switching circuit, and a user of the arc switching circuit realizes switching between cutting arc transfer arcs. When a loop is formed between the electrode and the nozzle to be conducted, the arc turning circuit works. As shown in fig. 2, the nozzle lead out+1 is further connected with the anode of the zener diode ZD4, one end of the resistors R125, C126, and the emitter of the IGBT T10-1; the electrode lead OUT-is also connected to one end of R35. The arc transfer circuit mainly triggers the arc transfer circuit above after detecting that the electrode is conducted with the nozzle, and the machine outputs a transfer arc; and when the current is large enough to exceed the current of the small arc, the triode circuit is conducted and is converted into a cutting arc for output. The arc transfer circuit is mainly used for realizing the conversion between cutting arc transfer arcs. ZYOUT is the output of the arc voltage.
When a loop is formed between the positive lead-out wire and the negative lead-out wire of the detection circuit 10, current flows through the light-emitting diode at the input side of the optocoupler U8, a voltage signal of 5V is transmitted to the CPU through the optocoupler U8, the CPU detects the voltage signal of 5V, the welding gun can work normally, and the arc striking of the welding gun can be carried out normally. If the nozzle and the electrode are not installed, the state is equivalent to that VOUT-not equal to vout+1, and the state between out+1 and OUT-is in an open state, no current flows through the diode at the input side of the optocoupler, and a voltage signal of 0V is transmitted to the CPU through the optocoupler. When the CPU detects a voltage signal of 0V, an alarm signal is sent out, and the given current is cut off, so that electric shock protection is realized.
Fig. 3 is a schematic diagram of the method for preventing electric shock according to the present invention. As shown in fig. 3, the electric shock protection method includes: s101, preparing an arc starting process for plasma cutting; s102, detecting whether a loop is formed between the electrode and the nozzle, outputting a detection signal, judging whether the detection signal is equal to 5V, entering S103 to perform normal arc striking if the detection signal is equal to 5V, entering S104 to send out an alarm signal if the detection signal is not equal to 5V, and cutting off current setting.
Compared with the prior art, the electric shock protection device and the method for the plasma cutting machine can detect whether the nozzle and the electrode are effectively installed, so that the purpose of electric shock protection is achieved. The detection circuit has simple structure, saves cost, occupies small actual space, does not need to additionally increase operation steps, and is convenient and stable to use.
On the other hand, the electric shock protection device and the method provided by the invention can detect whether the nozzle and the electrode are effectively installed or not at the same time, and have short time and quick response.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (4)
1. An anti-shock protection device for a plasma cutting machine, comprising:
the detection circuit detects whether a loop is formed between the electrode and the nozzle and outputs a detection signal;
the control unit receives the detection signal and starts the cutting machine or sends out an alarm signal according to the detection signal, and the alarm signal is used for cutting off the working current of the plasma cutting machine;
the first detection end of the detection circuit is connected with the electrode, and the second detection end of the detection circuit is connected with the nozzle; the first detection end is used for detecting Vout-, the second detection end is used for detecting Vout+1, and when Vout- =Vout+1, a loop is formed between the electrode and the nozzle;
the detection circuit comprises a power supply and a detection signal output unit, wherein the power supply supplies power to the detection circuit, and the detection signal output unit is used for outputting the detection signal according to whether a loop is formed between an electrode and a nozzle;
the power supply is an isolated power supply, and the signal output unit is an optical coupler;
the detection circuit comprises resistors R31 and R34, capacitors C51 and C52 and diodes D19 and D999, wherein one end of the resistor R31 is connected with an electrode, the other end of the resistor R31 is connected with an isolated power supply, one end of the resistor R31 is connected with the anode of the diode D19, and the other end of the resistor R31 is connected with the cathode of an input diode of the optocoupler; one end of the capacitor C51 is connected with the isolation power supply and the resistor R34, and the other end of the capacitor C is connected with the isolation power supply, the cathode of the diode D999 and the anode of the input diode of the optocoupler; the capacitor C52 is connected with the output side of the optocoupler, the cathode of the diode D19 is connected with the nozzle outgoing line, and the anode is connected with the resistor R31.
2. An anti-shock protection device according to claim 1, wherein the voltage of the isolated power supply is 12V.
3. The device of claim 1, wherein the detection signal is a voltage signal, the cutter is started when the voltage signal is 5V, and the alarm signal is sent when the voltage signal is 0V.
4. The shock protection device of claim 1, wherein the detection circuit is coupled to the arc turning circuit.
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| CN201810186900.8A CN108372349B (en) | 2018-03-07 | 2018-03-07 | Electric shock protection device and method for plasma cutting machine |
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| CN201810186900.8A CN108372349B (en) | 2018-03-07 | 2018-03-07 | Electric shock protection device and method for plasma cutting machine |
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| CN109709427B (en) * | 2018-12-30 | 2021-09-03 | 常州九圣焊割设备股份有限公司 | Method for detecting faults of consumable parts in plasma arc spray gun |
| CN109927187A (en) * | 2019-03-04 | 2019-06-25 | 山西中电科新能源技术有限公司 | Detect the method and silicon chip slicer sticky stick tooling of silicon rod slicing in place |
| CN114406424B (en) * | 2022-01-25 | 2023-04-14 | 常州九圣焊割设备股份有限公司 | Cutting torch protection method and device |
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| JPH0815668B2 (en) * | 1986-07-14 | 1996-02-21 | 日立精工株式会社 | Plasma cutting device |
| US4929811A (en) * | 1988-12-05 | 1990-05-29 | The Lincoln Electric Company | Plasma arc torch interlock with disabling control arrangement system |
| CN201183157Y (en) * | 2007-06-22 | 2009-01-21 | 唐山松下产业机器有限公司 | Short-circuit protection control circuit for connecting line of welding machine and air valve |
| CN102489851B (en) * | 2011-11-30 | 2014-04-16 | 广州亦高电气设备有限公司 | Plasma cutter |
| US9566657B2 (en) * | 2012-03-27 | 2017-02-14 | Illinois Tool Works Inc. | System and method for determining attachment and polarity of a welding electrode |
| CN104959721B (en) * | 2015-07-24 | 2017-05-10 | 上海沪工焊接集团股份有限公司 | Circuit and method for controlling guiding arc of plasma cutting machine |
| CN211305168U (en) * | 2018-03-07 | 2020-08-21 | 上海威特力焊接设备制造股份有限公司 | Electric shock protection device for plasma cutting machine |
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