Pre-air-supply control method and circuit and plasma cutting machine

Abstract

The invention provides a pre-air-supply control method, a pre-air-supply control circuit and a plasma cutting machine. The control method comprises the steps that a main control module responds to a cutting gun test signal and sends a gas control signal to a gas valve control module; the gas valve control module responds to the gas control signal and supplies test gas to the cutting gun at a first moment; the gas sensing device sends a gas feedback signal to the main control module at a second moment when sensing the test gas; and the main control module sets the target gas pre-supply time of the plasma cutting machine according to the time interval between the first moment and the second moment. The control method can help to form a stable plasma arc, and the arc striking success rate and the cutting quality of the plasma cutting machine are improved.

Description

Technical Field

[0001] The present application relates to the technical field of cutting machines, and in particular to a pre-gas control method, circuit and plasma cutting machine. Background Art

[0002] Plasma cutting machine is a kind of equipment that uses high temperature plasma arc to cut and process metal materials. Its cutting efficiency and quality are affected by many factors. Among them, the length of the cutting gun directly determines the time when the gas reaches the gun muzzle during the cutting process, and the accuracy of the gas arrival time affects the formation process of the plasma arc.

[0003] At present, the length of the cutting gun and the pre-gas time are usually determined by manual measurement or preset parameters. However, manual measurement or preset parameters rely on the operator's experience and are prone to errors, resulting in inaccurate pre-gas time, unstable plasma arc formation, and serious impact on the arc ignition success rate and cutting quality of the plasma cutting machine.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0005] Based on this, the embodiments of the present application provide a pre-gas control method, circuit and plasma cutting machine, which can help form a stable plasma arc and improve the arc striking success rate and cutting quality of the plasma cutting machine.

[0006] According to some embodiments, the present application provides a pre-gas control method, which is implemented by a control circuit, wherein the control circuit includes a main control module, a gas valve control module connected to the main control module, and a gas sensing device, wherein the gas sensing device is installed at the muzzle of a cutting gun of a plasma cutting machine;

[0007] The control method comprises the following steps:

[0008] The main control module sends a gas control signal to the gas valve control module in response to the cutting gun test signal;

[0009] The gas valve control module supplies the test gas to the cutting gun at a first moment in response to the gas control signal;

[0010] The gas sensing device sends a gas feedback signal to the main control module at a second moment when the test gas is sensed;

[0011] The main control module sets a target pre-gas supply time of the plasma cutting machine according to a time interval between the first moment and the second moment.

[0012] In some embodiments, a cutting gun access signal is used as the cutting gun test signal to trigger the main control module to send the gas control signal to the gas valve control module.

[0013] In some embodiments, the gas sensing device includes at least two test electrodes, and an electrode state feedback module connected to the two test electrodes;

[0014] The gas sensing device sends a gas feedback signal to the main control module at the second moment when the test gas is sensed, comprising the following steps:

[0015] When in the initial state, the two test electrodes are in contact with each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes;

[0016] The electrode state feedback module obtains the output voltage of the two test electrodes, and sends the gas feedback signal to the main control module when the output voltage exceeds a preset voltage threshold.

[0017] In some embodiments, the gas sensing device includes a gas pressure detection module;

[0018] The gas sensing device sends a gas feedback signal to the main control module at the second moment when the test gas is sensed, comprising the following steps:

[0019] The gas pressure detection module measures the gas pressure at the muzzle and sends the gas feedback signal to the main control module when the gas pressure exceeds a preset gas pressure threshold.

[0020] In some embodiments, setting the target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment comprises the following steps:

[0021] According to the time interval, the identification length of the cutting gun is obtained;

[0022] Acquire the corresponding relationship between a plurality of lengths of the cutting gun and a plurality of standard pre-gas supply times;

[0023] Based on the corresponding relationship, the standard pre-gas delivery time corresponding to the identification length is selected as the target pre-gas delivery time.

[0024] In some embodiments, after setting the target pre-gas delivery time, the control method further includes the following steps:

[0025] The target pre-gas delivery time is stored.

[0026] In some embodiments, the control method further comprises the following steps:

[0027] The main control module responds to the power-on signal of the cutting machine to determine whether the cutting gun access signal is received;

[0028] When it is determined that the cutting gun access signal is not received, the main control module generates an alarm message.

[0029] In some embodiments, in response to each cutting gun access signal, the main control module sets a target pre-gas supply time of the plasma cutting machine.

[0030] According to some embodiments, the present application provides, on another aspect, a pre-gas supply control circuit for implementing the control method according to any one of claims 1 to 8, comprising: a main control module, and a gas valve control module and a gas sensing device connected to the main control module;

[0031] The main control module is configured to: send a gas control signal to the gas valve control module in response to a cutting gun test signal;

[0032] The gas valve control module is configured to: supply test gas to the cutting gun at a first moment in response to the gas control signal;

[0033] The gas sensing device is installed at the muzzle of the cutting gun and is configured to: send a gas feedback signal to the main control module at a second moment when the test gas is sensed;

[0034] Wherein, the main control module is further configured to set a target pre-gas supply time of the plasma cutting machine according to a time interval between the first moment and the second moment.

[0035] In some embodiments, the gas sensing device includes: at least two test electrodes, and an electrode state feedback module connected to the two test electrodes;

[0036] When the two test electrodes are in an initial state, they contact each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes;

[0037] The electrode state feedback module is connected to the two test electrodes and is configured to: obtain the output voltage of the two test electrodes and feed back the output voltage to the main control module.

[0038] According to some embodiments, the present application provides a plasma cutting machine on another aspect, the plasma cutting machine comprising: a cutting gun, and the control circuit provided by the aforementioned embodiments.

[0039] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application.

[0040] The embodiments of the present application may or at least have the following advantages:

[0041] In the embodiment of the present application, the main control module supplies the test gas to the cutting gun according to the first moment of the gas valve control module, and the gas sensing device senses the test gas reaching the muzzle of the cutting gun at the second moment. The time interval between the first moment and the second moment represents the time required for the test gas to reach the muzzle of the cutting gun from the gas valve. The longer the time interval, the longer the length of the cutting gun, and therefore the longer the pre-gas supply time is required to ensure that the necessary gas environment is provided for the cutting area. According to the time interval between the first moment and the second moment, the target pre-gas supply time of the plasma cutting machine is set without manual intervention or additional measurement steps, which is conducive to improving the automation level of the control method.

[0042] Based on this, the main control module can accurately set the target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment, thereby effectively reducing the situation of too much or too little pre-gas supply, and avoiding the unstable formation of the plasma arc due to inaccurate pre-gas supply, thereby affecting the cutting efficiency. Especially for longer cutting guns, the time interval between the first moment and the second moment will be longer. The control method can automatically adjust the pre-gas supply time, thereby significantly improving the arc striking success rate. Therefore, the embodiment of the present application can help form a stable plasma arc, which is beneficial to improving the arc striking success rate and cutting quality of the plasma cutting machine.

[0043] Other advantages, objectives and features of the present application will be described in the following description to some extent, and will be apparent to those skilled in the art based on the following examination and study, or can be taught from the practice of the present application to some extent. The objectives and other advantages of the present application can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings.

[0045] Figure 1 A schematic diagram of the structure of a control circuit provided in some embodiments of the present application;

[0046] Figure 2 A flowchart of a control method provided in some embodiments of the present application;

[0047] Figure 3A schematic diagram of a flow chart of sending a gas feedback signal in a control method provided in some embodiments of the present application;

[0048] Figure 4 A schematic diagram of a flow chart for setting a target pre-gas delivery time in a control method provided in some embodiments of the present application;

[0049] Figure 5 A schematic diagram of a flow chart of generating alarm information in a control method provided in some embodiments of the present application.

[0050] Description of reference numerals:

[0051] 100 Main control module

[0052] 200 Gas valve control module

[0053] 300 Gas Sensing Device DETAILED DESCRIPTION

[0054] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0056] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0057] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0058] At present, the length of the cutting gun and the pre-gas time are usually determined by manual measurement or preset parameters. However, manual measurement or preset parameters rely on the operator's experience and are prone to errors, resulting in inaccurate pre-gas time, unstable plasma arc formation, and serious impact on the arc ignition success rate and cutting quality of the plasma cutting machine.

[0059] Based on this, the present application hopes to provide a solution that can solve the above technical problems, can help form a stable plasma arc, and improve the arc ignition success rate and cutting quality of the plasma cutting machine. The details will be described in the subsequent embodiments.

[0060] On the one hand, the present application provides a pre-gas control method. The control method can be used as follows Figure 1 The control circuit shown is implemented, and the control circuit includes a main control module 100, and a gas valve control module 200 and a gas sensing device 300 connected to the main control module 100; wherein the gas sensing device 300 can be installed at the muzzle of the cutting gun of the plasma cutting machine.

[0061] Please combine Figure 1 See also Figure 2 The control method may specifically include the following steps S100 to S400:

[0062] S100: the main control module 100 sends a gas control signal to the gas valve control module 200 in response to the cutting gun test signal.

[0063] S200: The gas valve control module 200 supplies test gas to the cutting gun at a first moment in response to the gas control signal.

[0064] S300: The gas sensing device 300 sends a gas feedback signal to the main control module 100 at the second moment when the test gas is sensed.

[0065] S400: The main control module 100 sets a target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment.

[0066] It should be noted that the "pre-gas supply" involved in this application, which can also be called "system pre-gas supply", refers to the gas supplied to the cutting area in advance before the plasma cutting machine starts cutting to help form a plasma arc and improve the cutting quality. The gas can include compressed air or inert gas (such as argon, nitrogen, etc.), the purpose of which is to provide the necessary gas environment for the cutting area before cutting begins.

[0067] In the control circuit provided in the present application, the main control module 100 supplies the test gas to the cutting gun according to the first moment of the gas valve control module 200, and the gas sensing device 300 senses the second moment when the test gas reaches the muzzle. The time interval between the first moment and the second moment represents the time required for the test gas to reach the muzzle of the cutting gun from the gas valve. The longer the time interval, the longer the length of the cutting gun, and therefore a longer pre-gas supply time is required to ensure that the necessary gas environment is provided for the cutting area. According to the time interval between the first moment and the second moment, the target pre-gas supply time of the plasma cutting machine is set without manual intervention or additional measurement steps, which is conducive to improving the automation level of the control method.

[0068] Based on this, the main control module 100 can accurately set the target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment, thereby effectively reducing the situation of too much or too little pre-gas supply, and avoiding the unstable formation of the plasma arc due to inaccurate pre-gas supply, thereby affecting the cutting efficiency. Especially for a longer cutting gun, the time interval between the first moment and the second moment will be longer, and the control method can automatically adjust the pre-gas supply time, thereby significantly improving the arc striking success rate. Therefore, the control circuit provided in the present application can help form a stable plasma arc, which is beneficial to improving the arc striking success rate and cutting quality of the plasma cutting machine, and is particularly suitable for a longer cutting gun, which can significantly improve the arc striking success rate.

[0069] Regarding step S100 , in some embodiments, the cutting gun access signal is used as a cutting gun test signal to trigger the main control module 100 to send a gas control signal to the gas valve control module 200 .

[0070] It should be noted that the "cutting gun access signal" involved in the above embodiment is a signal used to indicate that the cutting gun has been correctly connected and is ready. When the cutting gun access signal is generated, it indicates that the cutting gun has been able to receive control instructions and has the necessary conditions to start high-voltage discharge and ignite the plasma arc.

[0071] For step S200, as an example, the gas that is delivered to the cutting area in advance in the actual working scene can be used as the test gas, such as compressed air or inert gas (argon, nitrogen, etc.), which can simulate the gas flow more realistically and improve the accuracy of the cutting gun length recognition. In addition, by using the gas that will be used in the actual working scene, there is no need to prepare additional specific test gas, which can also avoid the increase of gas management costs.

[0072] For step S300, the gas sensing device 300 sends a gas feedback signal to the main control module 100 at the second moment when the test gas is sensed, indicating that the test gas has reached the muzzle at this moment. How to detect whether the test gas has reached the muzzle will be described below in conjunction with specific embodiments.

[0073] In some embodiments, the gas sensing device 300 of the control circuit includes at least two test electrodes and an electrode state feedback module connected to the two test electrodes.

[0074] Based on this, see Figure 3 In step S300 , the gas sensing device 300 sends a gas feedback signal to the main control module 100 at the second moment when the test gas is sensed, which may specifically include the following steps S310 to S320 .

[0075] In step S310, when the two test electrodes are in the initial state, they are in contact with each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes.

[0076] In step S320, the electrode state feedback module obtains the output voltage of the two test electrodes, and sends a gas feedback signal to the main control module 100 when the output voltage exceeds a preset voltage threshold.

[0077] In the above embodiment, the arrival of the test gas is sensed by the change in the short-circuit state of the two test electrodes. When no test gas arrives, the two test electrodes are in contact, forming a short circuit. In the short-circuit state, the voltage between the two test electrodes (i.e., the output voltage obtained by the electrode state feedback module) is 0. When the test gas reaches the muzzle, the two test electrodes will be blown apart and separated from each other, thereby interrupting the original short-circuit state. Once the two test electrodes are no longer short-circuited, a voltage can be generated between the two. Therefore, when the output voltage exceeds the preset voltage threshold (for example, the output voltage is greater than 0), it means that the two test electrodes are no longer short-circuited, and it can be determined that the test gas has reached the muzzle of the cutting gun.

[0078] The design structure of the two test electrodes and the electrode state feedback module is simple, easy to manufacture and install, and has high reliability and stability. The method of using two test electrodes and the electrode state feedback module to sense the test gas can provide more reliable and accurate gas sensing feedback, further improving the arc ignition success rate and cutting quality of the plasma cutting machine.

[0079] Ideally, the voltage between the two test electrodes in the short-circuit state is equal to 0. However, in practical applications, due to factors such as resistance and measurement instrument accuracy limitations, there will be a very small voltage value between the two test electrodes, and the voltage between the two is close to 0 but not strictly equal to 0. Therefore, the above embodiment sets a sufficiently low preset voltage threshold to distinguish between the short-circuit state and the state after gas arrival.

[0080] In other embodiments, the gas sensing device 300 of the control circuit includes a gas pressure detection module.

[0081] Based on this, in step S300, the gas sensing device 300 sends a gas feedback signal to the main control module 100 at the second moment when the test gas is sensed, which can be specifically expressed as follows:

[0082] The gas pressure detection module measures the gas pressure at the muzzle and sends a gas feedback signal to the main control module 100 when the gas pressure exceeds a preset gas pressure threshold.

[0083] In the above embodiment, when the test gas reaches the muzzle, the gas pressure at the muzzle changes due to the gas flow. By setting a preset gas pressure threshold, the preset gas pressure threshold can be determined based on the normal pressure range of the muzzle when no test gas passes through, and whether the test gas reaches the muzzle is determined accordingly.

[0084] The above embodiment directly measures the gas pressure at the muzzle, which can provide direct information about the existence and flow of gas. The gas pressure detection module (such as a gas pressure sensor) can respond quickly, thereby detecting the change of gas pressure at the muzzle in a timely manner.

[0085] For step S400, see Figure 4 In some embodiments, the following steps S410 to S430 may be used to set the target pre-gas supply time of the plasma cutting machine.

[0086] In step S410, the main control module 100 obtains the identification length of the cutting gun according to the time interval between the first moment and the second moment. This process does not require manual intervention or additional measurement steps, which is conducive to improving the automation level of the control method.

[0087] In step S420, the corresponding relationship between multiple lengths of the cutting gun and multiple standard pre-gas supply times is obtained.

[0088] As an example, before the equipment leaves the factory, multiple cutting guns of different lengths can be installed on the plasma cutting machine, and multiple different pre-gas times can be set for each cutting gun length; then the cutting gun can be pre-gas tested at multiple different pre-gas times, and the cutting effects of the current length of the cutting gun at different pre-gas times can be compared, and the pre-gas time that can achieve the best cutting effect can be selected as the standard pre-gas time corresponding to the current length. Combine multiple lengths with their corresponding multiple standard pre-gas times to form a corresponding relationship. Exemplarily, the corresponding relationship record can be saved in the database or memory storage of the plasma cutting machine for call; it can also be written into the technical documentation for reference in subsequent production, quality control and customer use.

[0089] In step S430, based on the corresponding relationship, the standard pre-gas delivery time corresponding to the identified length is selected as the target pre-gas delivery time.

[0090] In the above embodiment, by pre-establishing the correspondence between the length of the cutting gun and the standard pre-gas delivery time (for example, based on the test data before leaving the factory), the target pre-gas delivery time can be accurately selected, reducing the manual intervention required after being put into use, and avoiding the errors that may be caused by relying solely on experience or fixed value settings. In addition, with the above embodiment, the user does not need to have an in-depth understanding of the specific parameter adjustment, but only needs to operate the cutting gun as required to complete the precise setting, making the device easier to operate and more user-friendly.

[0091] For example, suppose that the following corresponding relationship is obtained through multiple groups of pre-gas tests: the standard pre-gas time corresponding to the cutting gun with a length of 5m is 350ms, the standard pre-gas time corresponding to the cutting gun with a length of 20m is 1s, and the standard pre-gas time corresponding to the cutting gun with a length of 10m is 700ms.

[0092] When the main control module 100 calculates that the time interval between the first moment and the second moment is 1s, based on the above correspondence, it is found that the cutting gun length corresponding to the standard pre-gas time of 1s is 20m. Therefore, it is known that the identification length of the cutting gun is 20m. Then the main control module 100 sets the target pre-gas time of the plasma cutting machine to 1s according to the identification length of the cutting gun of 20m.

[0093] In some embodiments, after the target pre-gas delivery time is set, the target pre-gas delivery time may also be stored. For example, the current identification length and target pre-gas delivery time may be saved to a database or internal storage of the device through the main control module 100, which may be helpful for subsequent troubleshooting or performance analysis, such as tracking the operating status of the plasma cutting machine at different time points, helping users or engineers analyze historical data, find problems, and optimize operations, etc.

[0094] Some embodiments are described below in detail by taking a cutting gun access signal as a cutting gun test signal as an example.

[0095] In some embodiments, see Figure 5 , the control method may further include the following steps S110 to S120.

[0096] In step S110, the main control module 100 determines whether a cutting gun access signal is received in response to a cutting machine power-on signal.

[0097] In step S120, when it is determined that the cutting gun access signal is not received, the main control module 100 generates an alarm message.

[0098] The above embodiment generates an alarm message when the cutting gun access signal is not received, which can remind the user to check the device connection status in time to avoid starting the plasma cutting machine in an incorrect state, causing equipment damage or other safety problems, which is beneficial to improving the reliability and safety of the plasma cutting machine during use.

[0099] In some embodiments, in response to each cutting gun connection signal, the main control module 100 sets a target pre-gas supply time of the plasma cutting machine.

[0100] It can be understood that during the use of the plasma cutting machine, whenever the cutting gun access signal is interrupted and a new cutting gun access signal is collected, it indicates that the cutting gun has been replaced or reconnected.

[0101] After the cutting gun is replaced or reconnected, the above embodiment automatically repeats steps S100 to S400 to complete the resetting of the target pre-gas time without manual adjustment by the user, thereby avoiding omissions that may be caused by manual operation and further reducing equipment preparation time, which is conducive to improving cutting efficiency.

[0102] Based on the same inventive concept, the present application also provides a pre-gas supply control circuit for implementing the control method provided in the above embodiment. The control circuit can also achieve the technical effects that can be achieved by the above control method, and will not be described in detail later.

[0103] Please continue reading Figure 1 The control circuit may specifically include: a main control module 100, and a gas valve control module 200 and a gas sensing device 300 connected to the main control module 100.

[0104] Among them, the main control module 100 is configured to: send a gas control signal to the gas valve control module 200 in response to the cutting gun test signal; the gas valve control module 200 is configured to: supply test gas to the cutting gun at a first moment in response to the gas control signal; the gas sensing device 300 is installed at the muzzle of the cutting gun, and is configured to: send a gas feedback signal to the main control module 100 at a second moment when the test gas is sensed.

[0105] In the control circuit provided in the present application, the main control module 100 can be used to set the target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment.

[0106] In the control circuit provided in some embodiments, the gas sensing device 300 may specifically include at least two test electrodes and an electrode state feedback module connected to the two test electrodes.

[0107] When the two test electrodes are in the initial state, they contact each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes. The electrode state feedback module is connected to the two test electrodes to obtain the output voltage of the two test electrodes and feed back the output voltage to the main control module.

[0108] It should be noted that the pre-gas control circuits in the embodiments of the present application can be used to implement the corresponding control methods. Therefore, the technical features between the method embodiments and the circuit embodiments can be replaced and supplemented with each other without causing conflicts, so that those skilled in the art can understand the technical content of the present application.

[0109] Those skilled in the art will understand that Figure 1 The structure shown in the figure is merely a schematic diagram of some modules related to the present application scheme, and does not constitute a limitation on the modules to which the present application scheme is applied. The specific control circuit may include more existing functional modules than those shown in the figure, or combine certain existing functional modules, or have a different module arrangement.

[0110] According to some embodiments, the present application provides a plasma cutting machine on the other hand, the plasma cutting machine includes: a cutting gun, and the control circuit provided by the above embodiments. Since the control circuit provided by the present application is used to implement the control method provided by the above embodiments, the technical effects that can be achieved by the above control method can also be achieved by the plasma cutting machine, which will not be described in detail here.

[0111] In the description of this specification, the description with reference to the terms "some embodiments", "as an example", "exemplarily", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0112] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features of the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A pre-gas control method, characterized in that: The control method is implemented by a control circuit, which includes a main control module, a gas valve control module and a gas sensing device connected to the main control module, and the gas sensing device is installed at the muzzle of a cutting gun of a plasma cutting machine; The control method comprises the following steps: The main control module sends a gas control signal to the gas valve control module in response to the cutting gun test signal; The gas valve control module supplies the test gas to the cutting gun at a first moment in response to the gas control signal; The gas sensing device sends a gas feedback signal to the main control module at a second moment when the test gas is sensed; The main control module sets a target pre-gas supply time of the plasma cutting machine according to a time interval between the first moment and the second moment.

2. The pre-gas control method according to claim 1, characterized in that: The cutting gun access signal is used as the cutting gun test signal to trigger the main control module to send the gas control signal to the gas valve control module.

3. The pre-gas control method according to claim 1, characterized in that: The gas sensing device comprises at least two test electrodes, and an electrode state feedback module connected to the two test electrodes; The gas sensing device sends a gas feedback signal to the main control module at the second moment when the test gas is sensed, comprising the following steps: When in the initial state, the two test electrodes are in contact with each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes; The electrode state feedback module obtains the output voltage of the two test electrodes, and sends the gas feedback signal to the main control module when the output voltage exceeds a preset voltage threshold.

4. The pre-gas control method according to claim 1, characterized in that: The gas sensing device includes a gas pressure detection module; The gas sensing device sends a gas feedback signal to the main control module at the second moment when the test gas is sensed, comprising the following steps: The gas pressure detection module measures the gas pressure at the muzzle and sends the gas feedback signal to the main control module when the gas pressure exceeds a preset gas pressure threshold.

5. The pre-gas control method according to claim 1, characterized in that: The step of setting the target pre-gas supply time of the plasma cutting machine according to the time interval between the first moment and the second moment comprises the following steps: According to the time interval, the identification length of the cutting gun is obtained; Acquire the corresponding relationship between a plurality of lengths of the cutting gun and a plurality of standard pre-gas supply times; Based on the corresponding relationship, the standard pre-gas delivery time corresponding to the identification length is selected as the target pre-gas delivery time.

6. The pre-gas control method according to claim 1, characterized in that: After setting the target pre-gas delivery time, the control method further comprises the following steps: The target pre-gas delivery time is stored.

7. The pre-gas control method according to claim 2, characterized in that: The control method further comprises the following steps: The main control module responds to the power-on signal of the cutting machine to determine whether the cutting gun access signal is received; When it is determined that the cutting gun access signal is not received, the main control module generates an alarm message.

8. The pre-gas control method according to claim 2 or 7, characterized in that: In response to each cutting gun access signal, the main control module sets a target pre-gas supply time of the plasma cutting machine.

9. A pre-gas control circuit, characterized in that: Used to implement the control method according to any one of claims 1 to 8, comprising: a main control module, and a gas valve control module and a gas sensing device connected to the main control module; The main control module is configured to: send a gas control signal to the gas valve control module in response to a cutting gun test signal; The gas valve control module is configured to: supply test gas to the cutting gun at a first moment in response to the gas control signal; The gas sensing device is installed at the muzzle of the cutting gun and is configured to: send a gas feedback signal to the main control module at a second moment when the test gas is sensed; Wherein, the main control module is further configured to set a target pre-gas supply time of the plasma cutting machine according to a time interval between the first moment and the second moment.

10. The pre-gas supply control circuit according to claim 9, characterized in that: The gas sensing device comprises: at least two test electrodes, and an electrode state feedback module connected to the two test electrodes; When the two test electrodes are in an initial state, they contact each other to form a short circuit; when the test gas reaches the muzzle, the two test electrodes are separated, interrupting the short circuit state of the two test electrodes; The electrode state feedback module is connected to the two test electrodes and is configured to: obtain the output voltage of the two test electrodes and feed back the output voltage to the main control module.

11. A plasma cutting machine, characterized in that: The plasma cutting machine comprises: a cutting gun, and a control circuit as claimed in claim 9 or 10.

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