CN211219101U - Current adjusting device for plasma cutting machine - Google Patents
Current adjusting device for plasma cutting machine Download PDFInfo
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- CN211219101U CN211219101U CN201820311854.5U CN201820311854U CN211219101U CN 211219101 U CN211219101 U CN 211219101U CN 201820311854 U CN201820311854 U CN 201820311854U CN 211219101 U CN211219101 U CN 211219101U
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Abstract
The utility model discloses a current regulation apparatus for plasma cutting machine, include: a detection circuit that detects whether a loop is formed between the workpiece and the nozzle and outputs a detection signal; the control unit receives the detection signal and starts the current adjusting unit according to the detection signal; and the current regulating unit is used for regulating the cutting current of the plasma cutting machine according to the detection signal. The utility model discloses disclose a current method for plasma cutting machine simultaneously.
Description
Technical Field
The invention relates to the technical field of plasma cutting machines, in particular to a current adjusting device and method for a plasma cutting machine.
Background
Plasma arc cutting is a process in which the heat of a high-temperature plasma arc is used to locally melt (vaporize) the metal at the cut of a workpiece and the molten metal is removed by the momentum of high-speed plasma to form a cut.
Plasma is a highly ionized gas heated to very high temperatures that transfers arc power to the workpiece, and the high heat melts and blows away the workpiece, creating a plasma arc cut condition. The compressed air enters the cutting torch and is distributed into two paths by the gas chamber, and plasma gas and auxiliary gas are formed. The plasma gas arc acts to melt the metal, while the auxiliary gas cools the various components of the torch and blows away the melted metal. The plasma cutting can be matched with different working gases to cut various metals which are difficult to cut by oxygen, and particularly, the cutting effect on nonferrous metals (stainless steel, aluminum, copper, titanium and nickel) is better; the plasma cutting method has the main advantages that when metal with small thickness is cut, the plasma cutting speed is high, particularly when a common carbon steel sheet is cut, the speed can reach 5-6 times that of an oxygen cutting method, a cutting surface is smooth and clean, the thermal deformation is small, and a heat affected zone is small.
Compared with the traditional cutting mode, the plasma cutting has the advantages of high efficiency, high precision, high stability and the like, and is particularly suitable for the requirements of mass production and processing and high-precision cutting. In addition, from the cost perspective, due to the fact that cutting gas cost is eliminated, plasma cutting is more economical relative to cost, and particularly when the plasma cutting method is applied to mass production, the processing cost control is more obvious. 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 materials such as stainless steel, aluminum and the like.
When the plasma cutting machine is used for cutting a workpiece, the plasma cutting machine is important for adjusting the cutting current of the plasma power supply, is the most important cutting process parameter and directly determines the cutting thickness and speed, namely the cutting capacity. With the increase of the cutting current of the plasma cutting machine, the plasma arc energy is increased, the cutting capability is improved, and the cutting speed is increased. However, in this process, since the cutting current of the plasma numerical control cutting machine is increased, the diameter of the plasma arc is increased, and the arc is thickened so that the notch is widened. Meanwhile, the excessive cutting current of the plasma cutting machine can increase the thermal load of the nozzle, cause the nozzle to be damaged prematurely and shorten the service life of the nozzle. Meanwhile, the cutting quality is reduced, and even normal cutting can not be carried out.
In view of the above, there is a need in the art for a new current regulator for a plasma cutting machine.
Disclosure of Invention
In view of the above, the present invention provides a current adjusting apparatus and method for a plasma cutting machine, which can adjust a cutting current of a power supply of the plasma cutting machine in real time according to a contact state of a workpiece and a nozzle.
In order to achieve the above object, the present invention discloses a current adjusting apparatus for a plasma cutting machine, comprising: a detection circuit that detects whether a loop is formed between the workpiece and the nozzle and outputs a detection signal; the control unit receives the detection signal and starts the current adjusting unit according to the detection signal; and the current regulating unit is used for regulating the cutting current of the plasma cutting machine according to the detection signal.
Furthermore, the first detection end of the detection circuit is connected with the workpiece, and the second detection end of the detection circuit is connected with the nozzle.
Furthermore, the first detection terminal is used for detecting Vout +1, the second detection terminal is used for detecting Vout-,
when Vout — Vout +1, a circuit is formed between the workpiece and the nozzle.
Furthermore, 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 the workpiece and the nozzle.
Furthermore, the power supply unit is an isolation power supply, and the signal output unit is an optical coupler.
Furthermore, the detection circuit also comprises resistors R8 and R9, capacitors C15 and C2, and diodes D1 and D4, wherein one end of the resistor R8 is connected with the cathode of the diode at the input side of the optical coupler and the anode of the diode D4, the other end of the resistor R8 is connected with the anode of the diode D1, one end of the resistor R9 is connected with the capacitor C15 and the isolated power supply, and the other end of the resistor R9 is connected with the nozzle; the capacitor 15 is connected to the isolated power supply; the capacitor C2 is connected with the cathode and the anode of the output side of the optical coupler.
Furthermore, the current regulating unit is a proportional-integral regulating circuit; when the detection signal is zero volt, the cutting current is not adjusted, and when the detection signal is 5 volt, the cutting current is adjusted.
Furthermore, the proportional-integral regulating circuit comprises resistors R205, R207, R208, R209, R249, R211 and R330, capacitors C205 and C207 and an operational amplifier U201D, wherein one end of the resistor R205 is connected with a given signal PPG, and the other end is connected with the cathode of the input end of the operational amplifier U201D; one end of the resistors R207 and R208 is connected with a feedback signal IF after being connected in series, and the other end is connected with the cathode of the input end of the operational amplifier U201D; the capacitor C205 is connected to two ends of the resistors R207 and R208 connected in series; one end of the capacitor C207 is connected to the resistor R249, and the other end is connected to the control unit and the output end of the operational amplifier U201D; one end of the resistor R209 is grounded, the other end is connected with the anode of the input end of the operational amplifier U201D, one end of the resistor R211 is grounded after the resistor R330 is connected in series, and the other end is connected with the control unit and the output end of the operational amplifier U201D.
The invention also discloses a current adjusting method for the plasma cutting machine, which comprises the following steps: the method comprises the following steps of firstly, detecting whether a loop is formed between a workpiece and a nozzle or not and outputting a detection signal; and secondly, receiving the detection signal and adjusting the cutting current of the plasma cutting machine according to the detection signal.
Compared with the prior art, the current adjusting device provided by the invention can adjust the cutting current of the power supply of the plasma cutting machine in real time according to the contact state of the workpiece and the nozzle, and avoids the sudden increase of the thermal load of the nozzle caused by the excessive current generated when the workpiece and the nozzle are contacted, so that the cutting quality is reduced and the service life of the nozzle is shortened.
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 hardware schematic block diagram of a current regulating device for a plasma cutter according to the present invention;
fig. 2 is a schematic circuit diagram of a current regulator for a plasma cutting machine according to the present invention.
Detailed Description
The core idea of the invention is to provide a current regulating device for a plasma cutting machine, which comprises a nozzle contact detection circuit and a current regulating circuit, and regulates cutting current by detecting whether the nozzle contacts with a workpiece.
In order to make the objects, advantages and features of the present invention more apparent, a current regulator for a plasma cutting machine according to the present invention will be described in further detail with reference to fig. 1 and 2. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present 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 hardware block diagram of a current regulator for a plasma cutter according to the present invention. As shown in fig. 1, during the operation of the plasma cutting machine, the workpiece 3 and the electrode 1 are respectively connected with the output anode and the output cathode, so that an arc is formed between the workpiece 3 and the electrode 1. This arc is compressed by the nozzle 2, emitting an arc with a high temperature and a high energy density. In this process, the electrode 1 mainly functions to conduct current and ignite an arc. The nozzle 2 acts to compress the arc, emitting an arc with a high temperature and a high energy density. The workpiece 3 is connected with the output anode, and an electric arc is formed between the electrode 1 and the workpiece, so that the purpose of cutting the workpiece is achieved. When the workpiece 3 is in contact with the nozzle 2, if the cutting current is too large, the thermal load on the nozzle 2 becomes too large, shortening the life of the nozzle 2, and the width of the cut is also increased, which affects the cutting quality. The current adjusting device comprises a detection circuit 10, which is used for connecting a nozzle 2 and a workpiece 3 of the plasma cutting machine, judging whether the nozzle 2 is contacted with the workpiece 3 or not and outputting a detection signal; and a control unit 20 for receiving the detection signal and starting the current adjusting unit 30 according to the detection signal. The current adjusting unit 30 adjusts the cutting current value according to the detection signal.
Fig. 2 is a schematic circuit diagram of a current regulator for a plasma cutting machine according to the present invention. As shown in fig. 2, the current adjusting device includes a detection circuit 10 for connecting with the nozzle 2 and the workpiece 3 of the plasma cutting machine, judging whether the nozzle 2 contacts with the workpiece 3 and outputting a detection signal; and a control unit 20 for receiving the detection signal and starting the current adjusting unit 30 according to the detection signal. The current adjusting unit 30 adjusts the cutting current value according to the detection signal. The detection circuit 10 comprises diodes D1 and D4, resistors R8 and R9, capacitors C15 and C2, an optical coupler U3, an isolation power supply 1515 and a CPU. One end of the resistor R8 is connected with the anode of the diode D1, and the other end of the resistor R8 is connected with the cathode of the diode at the input side of the optical coupler and the anode of the diode D4; one end of the resistor R9 is connected with the capacitor C15 and the isolated power supply 1515pin5, and the other end is connected with the nozzle outgoing line; the capacitor C15 is connected with pins 5 and 7 of the isolated power supply; the diode D4 is connected in reverse to the input-side light emitting diode; the capacitor C2 is connected to the photocoupler and the CPU. An isolated power supply 1515 is used to power the nozzle-to-workpiece contact detection circuitry. The operating voltage of the isolated power supply 1515 is 15V. The workpiece outlet OUT +1 and the nozzle outlet OUT-are also connected to an arc-turning circuit (not shown in the figure).
The current adjusting unit 30 is a proportional-integral adjusting circuit, the proportional-integral adjusting circuit includes resistors R205, R207, R208, R209, R249, R211, and R330, capacitors C205 and C207, and an operational amplifier U201D, one end of the resistor R205 is connected to a given signal PPG, and the other end is connected to the cathode of the input terminal of the operational amplifier U201D; one end of the resistors R207 and R208 is connected with a feedback signal IF after being connected in series, and the other end is connected with the cathode of the input end of the operational amplifier U201D; the capacitor C205 is connected to two ends of the resistors R207 and R208 connected in series; one end of the capacitor C207 is connected to the resistor R249, and the other end is connected to the control unit and the output end of the operational amplifier U201D; one end of the resistor R209 is grounded, the other end is connected with the anode of the input end of the operational amplifier U201D, one end of the resistor R211 is grounded after the resistor R330 is connected in series, and the other end is connected with the control unit and the output end of the operational amplifier U201D.
When the nozzle is contacted with a workpiece in the working process of the plasma cutting machine, the cutting current is high, the cutting quality is reduced, the thermal load of the nozzle is high, the nozzle is damaged early, and the service life of the nozzle is shortened. If the nozzle is not in contact with the workpiece, the cutting current is too low, which reduces the cutting speed and thickness, and affects the cutting ability. Therefore, the cutting current of the plasma cutting machine is required to be adjusted according to whether the nozzle is in contact with the workpiece or not in the cutting torch moving process, so that the service life of the nozzle is prolonged, and the cutting quality is improved. An OUT-line OUT-from the nozzle and an OUT-line OUT +1 from the workpiece. If the nozzle is not in contact with the workpiece in the cutting process, the voltage at the position of the nozzle and the workpiece is not equal, which is equivalent to VOUT- ≠ VOUT + 1. At this time, the distance between the nozzle on the left side and the workpiece contact detection circuit OUT +1 and OUT-is equivalent to an open circuit, so that no current flows on the light emitting diode on the input side of the optical coupler U3, and a voltage signal of 0V is output. The CPU detects a voltage signal of 0V, the current at the PPG given signal is equal to the current at the IF feedback signal, so that the current flowing through the operational amplifier is zero, the voltage at A is constant to 0, the signal fed to the CPU is 0, the PWM duty ratio of UC3895 is not adjusted, the current is not adjusted, and the working current is 100A.
If the nozzle is in contact with the workpiece in the cutting process, the contact is equivalent to VOUT < - > 1, a loop is formed between OUT +1 and OUT < - > in the contact detection circuit of the nozzle on the left side of the upper diagram and the workpiece, and current flows on the diode on the input side of the optical coupler, so that a 5V voltage signal is output. The CPU detects a 5V voltage signal, at the moment, the current at a PPG given signal is not equal to the current at an IF feedback signal, so that the current flows on the operational amplifier, the voltage at A is not 0, the signal fed to the CPU is not 0, the PWM duty ratio of the inverter power supply UC3895 is adjusted, and the current is adjusted to 40A. Therefore, in the cutting torch moving process, the CPU adjusts the cutting current through detecting whether the nozzle is contacted with the workpiece, so that the cutting quality is improved, the heat load of the nozzle is reduced, and the service life of the nozzle is prolonged.
The invention also discloses a method for adjusting the cutting current of the plasma cutting machine, which comprises the steps of respectively connecting the nozzle and the workpiece with the detection circuit, and detecting whether a loop is formed between the workpiece and the nozzle by the detection circuit and outputting a voltage signal. If a loop is formed, the nozzle is connected with the workpiece, and the cutting current is adjusted to 40A; if no loop is formed, indicating that the nozzle is not connected to the workpiece, no adjustment is made to the cutting current and the cutting current is maintained at 100A.
Compared with the prior art, the current adjusting device provided by the invention can adjust the cutting current of the power supply of the plasma cutting machine in real time according to the contact state of the workpiece and the nozzle, and avoids the sudden increase of the thermal load of the nozzle caused by the excessive current generated when the workpiece and the nozzle are contacted, so that the cutting quality is reduced and the service life of the nozzle is shortened.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (8)
1. A current regulating device for a plasma cutting machine, comprising:
a detection circuit that detects whether a loop is formed between the workpiece and the nozzle and outputs a detection signal;
the control unit receives the detection signal and starts the current adjusting unit according to the detection signal;
and the current adjusting unit adjusts the cutting current of the plasma cutting machine according to the detection signal.
2. The current regulator apparatus of claim 1, wherein a first sensing terminal of the sensing circuit is coupled to the workpiece and a second sensing terminal is coupled to the nozzle.
3. The current regulator of claim 2, wherein the first detection terminal is configured to detect Vout +1, and the second detection terminal is configured to detect Vout-, and when Vout — Vout +1, a loop is formed between the workpiece and the nozzle.
4. The current regulator according to claim 1, wherein the detection circuit includes a power supply source that supplies power to the detection circuit, and a detection signal output unit that outputs the detection signal depending on whether a loop is formed between the workpiece and the nozzle.
5. The current regulation device of claim 4 wherein the power supply is an isolated power supply and the signal output unit is an optocoupler.
6. The current regulator according to claim 4, wherein the detection circuit further comprises resistors R8 and R9, capacitors C15 and C2, and diodes D1 and D4, one end of the resistor R8 is connected to a cathode of an input side diode of an optical coupler and an anode of the diode D4, the other end of the resistor R8 is connected to an anode of the diode D1, one end of the resistor R9 is connected to the capacitor C15 and an isolated power supply, and the other end of the resistor R9 is connected to the nozzle; the capacitor 15 is connected with the isolated power supply; and the capacitor C2 is connected with the cathode and the anode of the output side of the optocoupler.
7. The current regulation device of claim 1 wherein the current regulation unit is a proportional-integral regulation circuit; when the detection signal is zero volt, the cutting current is not adjusted, and when the detection signal is 5 volt, the cutting current is adjusted.
8. The current regulator of claim 7, wherein the proportional integral regulator circuit comprises resistors R205, R207, R208, R209, R249, R211 and R330, capacitors C205 and C207, and an operational amplifier U201D, wherein one end of the resistor R205 is connected to a given signal PPG, and the other end is connected to the cathode of the input terminal of the operational amplifier U201D; one end of the resistors R207 and R208 is connected with a feedback signal IF after being connected in series, and the other end of the resistors R207 and R208 is connected with the cathode of the input end of the operational amplifier U201D; the capacitor C205 is respectively connected with two ends of the resistors R207 and R208 which are connected in series; one end of the capacitor C207 is connected with the resistor R249, and the other end of the capacitor C is connected with the control unit and the output end of the operational amplifier U201D; one end of the resistor R209 is grounded, the other end of the resistor R is connected with the anode of the input end of the operational amplifier U201D, one end of the resistor R211 is grounded after the resistor R330 is connected with the anode of the input end of the operational amplifier U201D in series, and the other end of the resistor R is connected with the output end of the operational amplifier U201D.
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| CN201820311854.5U CN211219101U (en) | 2018-03-07 | 2018-03-07 | Current adjusting device for plasma cutting machine |
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| CN201820311854.5U CN211219101U (en) | 2018-03-07 | 2018-03-07 | Current adjusting device for plasma cutting machine |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108296617A (en) * | 2018-03-07 | 2018-07-20 | 上海威特力焊接设备制造股份有限公司 | Regulating current device and method for plasma cutting machine |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108296617A (en) * | 2018-03-07 | 2018-07-20 | 上海威特力焊接设备制造股份有限公司 | Regulating current device and method for plasma cutting machine |
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