Calibration method, distance measurement method and laser cutting machine

Abstract

The present application provides a calibration method, a distance measurement method and a laser cutting machine, and relates to the field of distance measurement. The present application provides a calibration method, which includes: controlling the laser cutting head of the laser cutting machine to move n preset distances in sequence from the calibration workpiece surface to the direction away from the calibration workpiece surface, and obtaining n calibration frequencies and n calibration distances corresponding to the n preset distances; determining the conversion relationship of converting the calibration frequency to the corresponding frequency on the basic curve; based on the conversion relationship, obtaining a calibration curve reflecting the relationship between the calibration distance and the calibration frequency. The use of this calibration method can accurately and quickly realize the calibration of a specific laser cutting head and a workpiece surface of a specific material. The laser cutting machine calibrated by this calibration method can reduce the computational complexity and improve the measurement efficiency.

Description

Technical Field

[0001] The present application relates to the field of distance measurement, and in particular to a calibration method, a distance measurement method and a laser cutting machine. Background Art

[0002] Laser cutting is a non-contact processing method. Its cutting principle is to use the high energy of laser to melt the material and use high-pressure gas to blow away the slag to achieve cutting. The distance between the nozzle of the laser cutting head and the surface of the workpiece has a great influence on the cutting quality and cutting speed. The surface of the workpiece being cut is often uneven, and the distance between the laser cutting head and the surface being cut needs to be adjusted in real time. In order to accurately control the distance between the laser cutting head and the surface being cut, a capacitive sensor is often set in the laser cutting machine. The position of the laser cutting head is controlled by the relationship between the frequency detected by the capacitive sensor and the distance between the laser cutting head and the surface being cut.

[0003] At present, the calibration method for laser cutting machines is to collect enough relationships between capacitance frequencies and the distance between the cutting head and the surface being cut, and store these corresponding relationships; during processing, the real-time distance between the cutting head and the surface being cut is found from the stored corresponding relationships based on the real-time measured frequency; however, this method of saving data and searching has a long search process and takes up too much computer performance. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a calibration method, a distance measurement method and a laser cutting machine, by fitting a calibration curve that characterizes the relationship between the frequency measured by the capacitive sensor and the distance between the laser cutting head and the current workpiece surface on the basis of a basic curve. The calibration method can accurately and quickly calibrate a specific laser cutting head and a workpiece surface of a specific material, and a laser cutting machine calibrated by the calibration method can reduce computational complexity and improve measurement efficiency.

[0005] In a first aspect, an embodiment of the present application provides a calibration method, the method comprising: controlling the laser cutting head of a laser cutting machine to move n preset distances in sequence from a calibration workpiece surface to a direction away from the calibration workpiece surface, and obtaining n calibration frequencies and n calibration distances corresponding to the n preset distances; wherein n is greater than 1, the calibration distance is the distance between the laser cutting head and the calibration workpiece surface, and the calibration frequency is the frequency measured by the capacitive sensor in the laser cutting machine; determining a conversion relationship for converting the calibration frequency to a corresponding frequency on a basic curve; wherein the basic curve reflects the relationship between the distance and frequency between a preset laser cutting head and a preset workpiece surface; based on the conversion relationship, obtaining a calibration curve reflecting the relationship between the calibration distance and the calibration frequency.

[0006] In the above implementation process, the calibration method provided by the embodiment of the present application controls the laser cutting head of the laser cutting machine to move n preset distances in sequence from the calibration workpiece surface to the direction away from the calibration workpiece surface, and obtains n calibration frequencies and n calibration distances corresponding to the n preset distances; further converts the calibration frequency to the conversion relationship of the corresponding frequency on the basic curve, and then determines the calibration curve reflecting the relationship between the calibration distance and the calibration frequency based on the conversion relationship. The calibration method provided by the embodiment of the present application does not need to obtain a large amount of calibration data, so the storage space requirement of the device is not high; since the data obtained during the calibration process is small, the calibration speed can also be accelerated and the calibration efficiency can be improved.

[0007] Optionally, in an embodiment of the present application, a conversion relationship for transforming the calibration frequency into a corresponding frequency on the basic curve is determined, including: substituting each calibration distance into the basic curve to obtain the basic frequency corresponding to each calibration distance in the basic curve, and obtaining a total of n basic frequencies; dividing the basic curve into n-1 interval segments with every two adjacent basic frequencies as endpoints; calculating the relationship between the basic frequency and the calibration frequency in each of the n-1 interval segments to obtain n-1 conversion relationships corresponding to the n-1 interval segments.

[0008] Optionally, in an embodiment of the present application, calculating the relationship between the base frequency and the calibration frequency in the mth interval segment of the n-1 interval segments to obtain the mth conversion relationship corresponding to the mth interval segment includes: obtaining the mth calibration frequency and the mth fundamental frequency , the composition point ( ); Get the m+1th calibration frequency and the m+1th fundamental frequency , the composition point ( ); put the point ( ) and point ( ) Substitute the transformation relationship into the equation =aF+b to determine the conversion coefficients a and b; where m is greater than or equal to 1 and less than or equal to n-1.

[0009] In the above implementation process, in the calibration method provided in the embodiment of the present application, the calibration heights measured by the preset distance are substituted into the basic curve respectively to obtain the corresponding basic frequencies; based on the calibration frequency measured by the preset distance and the obtained basic frequency, the conversion relationship between the two is obtained; thereby, the connection between the basic curve and the calibration workpiece is established, and the idea of ​​segmented conversion is proposed in this process. The conversion coefficients of the curve segments corresponding to each interval segment may be different, which can adapt well to different measurement heights. The accuracy of the laser cutting machine calibrated by such a calibration method in later measurements can also be improved.

[0010] Optionally, in an embodiment of the present application, based on the conversion relationship, a calibration curve reflecting the relationship between the calibration distance and the calibration frequency is obtained, including: substituting the relationship between each basic frequency and the calibration frequency into the basic curve to obtain the calibration curve.

[0011] In the above implementation process, after obtaining the conversion relationship, the calibration method provided in the embodiment of the present application can directly bring the conversion relationship into the basic curve, avoiding complicated calculation steps during measurement, making the distance calculation process simpler and more efficient, and increasing the usability of the calibration method.

[0012] Optionally, in an embodiment of the present application, the method also includes: using the conversion relationship corresponding to the first interval segment after the calibration frequency is stabilized as the conversion relationship corresponding to at least one interval segment before the calibration frequency is stabilized; and / or using the conversion relationship of the n-1th interval segment as the conversion relationship corresponding to at least one interval segment in which the calibration frequency does not change with the calibration distance; wherein the n-1th interval segment is the last interval segment in which the calibration frequency changes with the calibration distance.

[0013] In the above implementation process, using the conversion relationship after the calibration frequency is stabilized for the unstable interval can reduce the frequency fluctuation caused by environmental factors or mechanical problems. Using the same stable conversion relationship repeatedly in different intervals can simplify the calibration process and reduce the number of multiple conversion relationships that need to be measured and stored.

[0014] Optionally, in an embodiment of the present application, the preset distance increases as the calibration distance increases.

[0015] In the above implementation process, the closer the laser cutting head is to the calibration surface, the more obvious the frequency change is; therefore, the preset distance can be set in a manner such that the preset distance increases with the increase of the calibration distance, thereby reducing the complexity and cost of calibration.

[0016] In a second aspect, an embodiment of the present application provides a distance measurement method, which includes: controlling the laser cutting head of the laser cutting machine to move from the current workpiece surface to the cutting distance in a direction away from the current workpiece surface, and obtaining a real-time frequency corresponding to the cutting distance; wherein the cutting distance is the distance between the laser cutting head and the current workpiece surface, and the real-time frequency is the frequency measured by the capacitive sensor in the laser cutting machine; the real-time frequency is brought into the calibration curve to obtain the real-time distance between the laser cutting head and the current workpiece surface; wherein the calibration curve is a representation of the relationship between the frequency measured by the capacitive sensor and the distance between the laser cutting head and the current workpiece surface.

[0017] In the above implementation process, through the distance measurement method provided in the embodiment of the present application, the real-time frequency is substituted into the calibration curve to obtain the real-time distance, and the distance between the laser cutting head and the current workpiece surface is controlled by the real-time distance; in this process, the real-time distance at each moment is obtained with high efficiency and low complexity, thereby improving the processing efficiency of the workpiece.

[0018] Optionally, in an embodiment of the present application, the real-time frequency is substituted into the calibration curve to obtain the real-time distance, including: determining a target interval segment of the real-time frequency on the calibration curve; wherein the calibration curve is a segmented curve; and the real-time frequency is substituted into the curve segment of the calibration curve corresponding to the target interval segment to obtain the real-time altitude.

[0019] In the above implementation process, in order to determine the real-time distance, the target interval segment of the real-time frequency on the calibration curve is first determined, and the real-time frequency is substituted into the curve segment of the calibration curve corresponding to the target interval segment to obtain the real-time height; thereby, the real-time height can be determined quickly and accurately, and the slight distance changes between the cutting head and the workpiece surface during the workpiece cutting process can be responded to at a faster speed.

[0020] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are read and executed by a processor, the steps in the above-mentioned calibration method and / or distance measurement method are executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A calibration flow chart provided for an embodiment of the present application;

[0023] Figure 2 A flowchart for obtaining the conversion relationship provided in the embodiment of the present application;

[0024] Figure 3 Another calibration flow chart provided for an embodiment of the present application;

[0025] Figure 4 A schematic diagram of a module of a laser cutting head provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment or a part of a code, and a module, a program segment or a part of a code contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they may sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or the flowchart, and the combination of boxes in the block diagram and / or the flowchart, can be implemented by a dedicated hardware-based system that performs a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions. In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist separately, or two or more modules can be integrated to form an independent part.

[0027] Laser cutting is a non-contact processing method. Its cutting principle is to use the high energy of laser to melt the material and use high-pressure gas to blow away the slag to achieve cutting. In order to accurately control the distance between the laser cutting head and the surface to be cut, a capacitive sensor is often set in the laser cutting machine. The position of the laser cutting head is controlled by the relationship between the frequency detected by the capacitive sensor and the distance between the laser cutting head and the surface to be cut.

[0028] The distance between the laser cutting head nozzle and the workpiece surface has a great influence on the cutting quality and cutting speed. The surface of the workpiece being cut is often uneven, and the distance between the laser cutting head and the cut surface needs to be adjusted in real time; therefore, the relationship between the frequency measured by the capacitive sensor in the laser cutter and the distance between the cutting head and the cut surface is extremely important. On the other hand, for different workpieces, the material of the workpiece may be different. When the material of the workpiece changes, the frequency characteristics of the distance between the laser cutting head nozzle and the workpiece and the capacitance are different; therefore, after replacing the workpiece of different materials, the frequency measured by the capacitive sensor and the distance between the cutting head and the cut surface need to be calibrated, so that the corresponding distance between the cutting head and the cut surface can be accurately determined according to the frequency measured by the capacitive sensor during the cutting process.

[0029] In the comparative embodiment, the method used to calibrate the frequency measured by the capacitance sensor and the distance between the cutting head and the surface to be cut is: control the laser cutting head to lift up from the surface of the workpiece to be processed, record the frequency of the capacitance and the corresponding lifting height in each sampling period, obtain a sufficient number of corresponding relationships between the capacitance frequency and the height, and store a large number of corresponding relationships between the capacitance frequency and the height; when processing the workpiece, find the target height from the stored corresponding relationship according to the frequency measured in real time, and adjust the distance between the cutting head and the surface to be cut according to the target height.

[0030] The inventors have found that in this process, in order to collect enough data, the movement of the laser cutting head needs to be very slow during the calibration process, which causes the entire calibration process to take a long time; and because a large amount of data needs to be saved, the calibration device is required to have a sufficiently large storage space; on the other hand, during the processing process, it is necessary to search for corresponding relationships in the large amount of stored data. The entire search process is relatively long and will take up too many computer resources.

[0031] Based on this, the present application provides a calibration method, which controls the laser cutting head to move away from the workpiece surface on the basis of a basic curve, and in this process obtains the correspondence between the distance between a target number of laser cutting heads and the workpiece surface and the frequency measured by the capacitive sensor. According to the correspondence between the distance between the laser cutting head and the workpiece surface and the frequency measured by the capacitive sensor, on the basis of the basic curve, a calibration curve is fitted to characterize the relationship between the frequency measured by the capacitive sensor and the distance between the laser cutting head and the current workpiece surface.

[0032] Please see Figure 1 , Figure 1 The calibration flow chart provided in the embodiment of the present application; the calibration method provided in the present application can be Figure 4 The electronic device is executed, and the calibration method comprises the following steps:

[0033] Step S100: Control the laser cutting head of the laser cutting machine to move n preset distances in sequence from the calibration workpiece surface to a direction away from the calibration workpiece surface, and obtain n calibration frequencies and n calibration distances corresponding to the n preset distances.

[0034] Among them, n is greater than 1, and the value of n can be determined according to the storage space inside the laser cutting machine. For example, n can be a value less than 100, such as 16, 20, 32, 50, etc. The calibration distance is the distance between the laser cutting head and the calibration workpiece surface, and the calibration frequency is the frequency measured by the capacitive sensor in the laser cutting machine.

[0035] In the above step S100, the laser cutting head of the laser cutting machine is controlled to move from the calibration workpiece surface to a direction away from the calibration workpiece surface, wherein the movement in the direction away from the calibration workpiece surface can start with the laser cutting head touching the calibration workpiece surface and detecting a contact signal indicating that the laser cutting head touches the calibration workpiece surface.

[0036] For example, the calibration workpiece is placed on a horizontal plane, and the laser cutting machine is set in a direction perpendicular to the surface of the calibration workpiece; after the laser cutting head contacts the surface of the calibration workpiece, the distance at which the laser cutting head contacts the surface of the calibration workpiece is determined to be 0; the laser cutting head of the laser cutting machine is controlled to move upward from the horizontal plane. In this scheme, moving n preset distances is n pre-set distances, and each time it moves according to the pre-set preset distance; for example, 10 preset distances are pre-set to be 0.1mm, 0.1mm, 0.1mm, 0.2mm, 0.2mm, 0.4mm, 0.4mm, 0.4mm, 0.5mm, 1mm respectively, then the first, second and third times move 0.1mm each time, the fourth and fifth times move 0.2mm each time, the sixth to eighth times move 0.4mm each time, the ninth time moves 0.5mm, and the tenth time moves 1mm. Of course, the number of preset distances can also be other numbers, and the size of each preset distance can also be adjusted, which will not be repeated.

[0037] Each movement gets a calibration frequency and a calibration distance. The calibration frequency is the frequency measured by the capacitive sensor. Generally speaking, when an object approaches or moves away from the sensor, the value of the capacitance will change, resulting in changes in the electric field. These changes can be converted into frequency signals through the circuit. The calibration distance is the distance between the laser cutting head and the calibration workpiece surface. For example, if the first movement is 0.1mm, the first measured calibration distance is 0.1mm; if the second movement is 0.1mm, the second measured calibration distance is 0.2mm, and so on.

[0038] Optionally, after all calibration frequencies and calibration distances are acquired, the laser cutting head is moved to a safe position.

[0039] Step S200: determining a conversion relationship for converting the calibration frequency to a corresponding frequency on the basic curve.

[0040] In the above step S200, the conversion relationship required to transform the calibration frequency to the corresponding frequency on the basic curve is determined. The basic curve is the relationship between the distance and frequency between the preset laser cutting head and the preset workpiece surface; the relationship between the distance and frequency between the preset laser cutting head and the preset workpiece surface can be obtained in the following way: control the preset laser cutting head to start from the preset workpiece surface and move in a direction away from the preset workpiece surface, and obtain enough sets of frequencies and distances in the process, and fit these frequencies and distances to obtain the basic curve. In other words, the basic curve can reflect the relationship between the distance and frequency between a specific laser cutting head and a specific workpiece, and the conversion relationship in the embodiment of the present application is to establish the connection between the preset workpiece and the calibration workpiece.

[0041] For example, under certain circumstances, the basic curve corresponding to the relationship between the distance frequency between the preset laser cutting head and the preset workpiece surface can be expressed as:

[0042] ,

[0043] Wherein, H is the distance between the preset laser cutting head and the preset workpiece surface, and F is the frequency measured by the capacitive sensor in the laser cutting machine where the preset laser cutting head is located; , , , , and m are coefficients related to the environment, laser cutting head and workpiece. , , , , and m are fixed numbers.

[0044] Step S300: Based on the conversion relationship, a calibration curve reflecting the relationship between the calibration distance and the calibration frequency is obtained.

[0045] Finally, a calibration curve reflecting the relationship between the calibration distance and the calibration frequency is obtained based on the conversion relationship. This calibration curve can obtain the corresponding distance according to the real-time frequency during the measurement process, thereby controlling the distance between the laser cutting head and the workpiece surface in real time.

[0046] Exemplarily, 16 preset distances are pre-set, respectively, as follows: 0.1mm, 0.1mm, 0.2mm, 0.2mm, 0.4mm, 0.5mm, 0.5mm, 0.5mm, 0.5mm, 1mm, 1mm, 1mm, 2mm, 2mm, 4mm and 6mm; the calibration distances obtained by each movement are 0.1mm, 0.2mm, 0.4mm, 0.6mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 14mm, 20mm; the calibration frequency measured each time is , , , , , , , , … , . Further, it is determined that , , , , , , , , … , The conversion relationship of the corresponding frequency on the basic curve is transformed; then according to the conversion relationship, the corresponding frequency of 0.1mm, 0.2mm, 0.4mm, 0.6mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 14mm, 20mm and , , , , , , , , … , The calibration curve of the relationship between them.

[0047] pass Figure 1It can be known that the calibration method provided in the embodiment of the present application controls the laser cutting head of the laser cutting machine to move n preset distances in sequence from the calibration workpiece surface to the direction away from the calibration workpiece surface, and obtains n calibration frequencies and n calibration distances corresponding to the n preset distances; further converts the calibration frequency to the conversion relationship of the corresponding frequency on the basic curve, and then determines the calibration curve reflecting the relationship between the calibration distance and the calibration frequency based on the conversion relationship. The calibration method provided in the embodiment of the present application does not need to obtain a large amount of calibration data, so the storage space requirement of the device is not high; since the data obtained during the calibration process is small, the calibration speed can also be accelerated and the calibration efficiency can be improved.

[0048] Please see Figure 2 , Figure 2 The flowchart of obtaining the conversion relationship provided in the embodiment of the present application; the above step S200 determines that the conversion relationship of converting the calibration frequency to the corresponding frequency on the basic curve can be achieved by the following steps:

[0049] Step S210: Substitute each calibration distance into the basic curve to obtain the basic frequency corresponding to each calibration distance in the basic curve, and obtain n basic frequencies in total.

[0050] In the above step S210, each calibration distance is brought into the basic curve to obtain the frequency corresponding to each calibration distance in the basic curve, a total of n basic frequencies; Parameters in =-3.372e+04, =3.651e+07, =-3.349e+07, =-4.75e+05, =4.961e+05, m=74, an example is given as follows: Continuing with the above 16 preset distances as an example, if the calibration distances 0.1mm, 0.2mm, 0.4mm, 0.6mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 14mm, 20mm are sequentially substituted into the H of the basic function, each calibration distance can calculate the corresponding frequency in the basic curve, which is expressed as , … , a total of 16 basic frequencies.

[0051] Step S220: Taking every two adjacent fundamental frequencies as endpoints, the fundamental curve is divided into n-1 interval segments.

[0052] In the above step S220, the basic curve is divided into n-1 non-interval segments with every two adjacent basic frequencies as endpoints; continuing to take the above 16 preset distances as an example, 16 basic frequencies are obtained. , … After that, the basic curve is divided into 15 intervals with every two adjacent basic frequencies as endpoints. to is the first interval segment, to For the second interval... to It is the 15th interval segment.

[0053] Step S230: Calculate the relationship between the basic frequency and the calibration frequency in each of the n-1 interval segments to obtain n-1 conversion relationships corresponding to the n-1 interval segments.

[0054] In the above step S230, the relationship between the basic frequency and the calibration frequency in each of the n-1 intervals is calculated to obtain n-1 conversion relationships, which correspond to the n-1 intervals respectively. The conversion relationship is the relationship between the basic frequency and the calibration frequency, that is, the basic frequency , … Convert to the calibration frequency , … The relationship formula.

[0055] Exemplarily, calculating the relationship between the base frequency and the calibration frequency in the mth interval segment among the n-1 interval segments to obtain the mth conversion relationship corresponding to the mth interval segment may be achieved by the following method:

[0056] First, get the mth calibration frequency and the mth fundamental frequency , the composition point ( ).

[0057] Further, obtain the m+1th calibration frequency and the m+1th fundamental frequency , the composition point ( ).

[0058] Finally, the point ( ) and point ( ) Substitute the transformation relationship into the equation =aF+b to determine the conversion coefficients a and b. Where m is greater than or equal to 1 and less than or equal to n-1. That is, by solving the equation system Find the conversion coefficients a and b.

[0059] In some embodiments, three adjacent calibration frequencies may also be divided into an interval segment, for example, based on the calibration frequency , , , where m is greater than or equal to 2 and less than or equal to n-1. The corresponding curve segment is divided into an interval segment, then the corresponding calibration frequency , , The corresponding fundamental frequency is , , , thus we get three sets of points ( )、( )and( ), substitute these three sets of points into the transformation relationship In this case, the conversion coefficients are a, b, and c. By solving the system of equations

[0060] The conversion coefficients a, b and c in this case are obtained.

[0061] It should be understood that the conversion relationship corresponding to the conversion relationship referred to in the embodiments of the present application is not limited to =aF+b or In practical applications, the more frequency points are obtained in an interval segment, the more accurate the corresponding conversion is.

[0062] It can be seen that in the calibration method provided in the embodiment of the present application, the calibration heights measured by the preset distance are substituted into the basic curve respectively to obtain the corresponding basic frequencies; based on the calibration frequency measured by the preset distance and the obtained basic frequency, the conversion relationship between the two is obtained; thereby, the connection between the basic curve and the calibration workpiece is established, and the idea of ​​segmented conversion is proposed in this process. The conversion coefficients of the curve segments corresponding to each interval segment may be different, which can adapt well to different measurement heights. The accuracy of the laser cutting machine calibrated by such a calibration method in later measurements can also be improved.

[0063] In an optional embodiment, the above step S300 may be implemented by obtaining a calibration curve reflecting the relationship between the calibration distance and the calibration frequency based on the conversion relationship by substituting the relationship between each basic frequency and the calibration frequency into the basic curve to obtain the calibration curve.

[0064] For example, the basic curve is divided into two adjacent basic frequencies. Divided into n-1 segments, the mth conversion relationship corresponding to the mth interval segment is =aF+b as an example (at this time, , , , , , m, a and b are all known parameters), =aF+b into ,get , this is the calibration curve.

[0065] It can be seen that after obtaining the conversion relationship, the calibration method provided in the embodiment of the present application can directly bring the conversion relationship into the basic curve, avoiding complicated calculation steps during measurement, making the distance calculation process simpler and more efficient, and increasing the usability of the calibration method.

[0066] In an optional embodiment, the conversion relationship corresponding to the first interval segment after the calibration frequency is stabilized is used as the conversion relationship corresponding to at least one interval segment before the calibration frequency is stabilized.

[0067] It should be noted that when the detection part of the capacitive sensor is in full contact with the surface of the measured object, the capacitance value may be affected by factors such as tiny mechanical friction, vibration or unevenness, which may cause the capacitance value to fluctuate around zero height, thereby causing the frequency value to be unstable.

[0068] Therefore, the conversion relationship corresponding to the first interval segment after the calibration frequency is stabilized can be used as the conversion relationship corresponding to at least one interval segment before the calibration frequency is stabilized; for example, and The fourth interval segment with the endpoint is the first interval segment after the frequency stabilizes, so the interval segment with 0 and The first interval segment with and The second interval segment with endpoints and The conversion relationship of the third interval segment as the endpoint uses the conversion relationship of the fourth interval segment, that is, the conversion coefficients of these five interval segments are the same.

[0069] In an optional embodiment, the conversion relationship of the n-1th interval segment is used as the conversion relationship corresponding to at least one interval segment in which the calibration frequency does not change with the calibration distance; wherein the n-1th interval segment is the last interval segment in which the calibration frequency changes with the calibration distance.

[0070] When the laser cutting head is far away from the calibration surface, the frequency measured by the capacitive sensor will remain basically unchanged. Therefore, the conversion relationship of the last interval segment of the calibration frequency change can be used for the conversion relationship of the interval segment where the calibration frequency does not change with the calibration distance.

[0071] For example, 16 preset distances are pre-set to be 0.1mm, 0.1mm, 0.2mm, 0.2mm, 0.4mm, 0.5mm, 0.5mm, 0.5mm, 0.5mm, 1mm, 1mm, 1mm, 2mm, 2mm, 4mm, 6mm, 10mm, 10mm; the calibration distances obtained by each movement are 0.1mm, 0.2mm, 0.4mm, 0.6mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 14mm, 20mm, 30mm, 40mm; the calibration frequency is from If the initial value remains unchanged, the conversion relationship corresponding to the 15th interval segment is used as the conversion relationship between the two interval segments from 20 mm to 40 mm.

[0072] It can be seen that using the conversion relationship after the calibration frequency is stabilized for the unstable interval can reduce the frequency fluctuation caused by environmental factors or mechanical problems. Using the same stable conversion relationship repeatedly in different intervals can simplify the calibration process and reduce the number of multiple conversion relationships that need to be measured and stored.

[0073] In an optional embodiment, the preset distance increases as the calibration distance increases.

[0074] For example, the 16 preset distances are 0.1mm, 0.1mm, 0.2mm, 0.2mm, 0.4mm, 0.5mm, 0.5mm, 0.5mm, 0.5mm, 1mm, 1mm, 1mm, 2mm, 2mm, 4mm, 6mm; the corresponding calibration distances are 0.1mm, 0.2mm, 0.4mm, 0.6mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 14mm, 20mm. It can be seen that the size of the preset distance increases with the increase of the calibration distance.

[0075] Since the closer the laser cutting head is to the calibration surface, the more obvious the frequency change is; therefore, the preset distance can be set in such a way that the preset distance increases with the increase of the calibration distance, thereby reducing the complexity and cost of calibration.

[0076] Please see Figure 3 , Figure 3 Another calibration flow chart provided in an embodiment of the present application, Figure 4 The electronic equipment in Figure 3 The calibration method is performed by following the procedure. Taking setting 16 preset distances as an example, the following is explained:

[0077] After starting calibration, control the laser cutting head (Z axis) of the laser cutting machine to move downward.

[0078] If the electronic device does not receive the plate collision signal, and the soft limit has been exceeded or the hard limit signal has been triggered, the laser cutting head is controlled to stop moving and the calibration failure is returned. If the soft limit has not been exceeded or the hard limit signal has not been triggered, the laser cutting head continues to be controlled to move downward.

[0079] If the electronic device receives the plate-touching limit signal, it controls the laser cutting head to stop moving downward and controls the laser cutting head to move upward along the Z axis for a total of 16 movements, each time at a preset distance, and each time recording the capacitance frequency value and height until 16 sets of data are recorded.

[0080] After recording 16 sets of data, lift the laser cutting head to a safe position.

[0081] Furthermore, based on the 16 sets of recorded data, curve fitting is performed. For the specific method of curve fitting, please refer to the previous description. The coefficients of the expression of the corresponding relationship between the capacitance frequency value and the height are calculated, and all the coefficients are saved, and finally the calibration is completed.

[0082] In some embodiments, the electronic device may also bring the conversion relationship corresponding to each corresponding relational expression coefficient into the basic curve to obtain a piecewise function of frequency and height.

[0083] The present application also provides a distance measurement method, in which the laser cutting machine used in the distance measurement method is a laser cutting machine calibrated using the above calibration method. The distance measurement method can be implemented in the following manner:

[0084] Control the laser cutting head of the laser cutting machine to move from the current workpiece surface to the cutting distance in the direction away from the current workpiece surface, and obtain the real-time frequency corresponding to the cutting distance. Substitute the real-time frequency into the calibration curve to obtain the real-time distance between the laser cutting head and the current workpiece surface.

[0085] Among them, the cutting distance is the distance between the laser cutting head and the current workpiece surface, the real-time frequency is the frequency measured by the capacitive sensor in the laser cutting machine; the calibration curve is a representation of the relationship between the frequency measured by the capacitive sensor and the distance between the laser cutting head and the current workpiece surface.

[0086] In the above implementation process, the laser cutting head starts cutting after it moves to the cutting distance. During the cutting process, the frequency measured by the capacitive sensor is obtained in real time. For workpieces with uneven surfaces, when the frequency measured by the capacitive sensor changes during the cutting process, the current cutting position and the cutting position at the previous moment are not at the same height, and the position of the laser cutting head needs to be adaptively adjusted. Each time the position is adjusted, the real-time frequency obtained by the capacitive sensor is brought into the calibration curve to obtain the real-time distance between the laser cutting head and the current workpiece surface. Alternatively, the laser cutting head starts cutting after it moves to the cutting distance. During the cutting process, the real-time frequency measured by the capacitive sensor is obtained in real time. The real-time frequency at each moment is substituted into the calibration curve to obtain the real-time distance between the laser cutting head and the current workpiece surface at each moment. The position of the laser cutting head is controlled at each moment by the real-time distance at that moment.

[0087] The calibration curve can be determined by the calibration method provided above, which will not be described in detail.

[0088] Through the distance measurement method provided in the embodiment of the present application, the real-time frequency is substituted into the calibration curve to obtain the real-time distance, and the real-time distance is used to control the distance between the laser cutting head and the current workpiece surface; in this process, the real-time distance at each moment is obtained with high efficiency and low complexity, thereby improving the processing efficiency of the workpiece.

[0089] In an optional embodiment, the real-time frequency is brought into the calibration curve to obtain the real-time altitude, including:

[0090] Determine the target interval segment of the real-time frequency on the calibration curve; wherein the calibration curve is a segmented curve; bring the real-time frequency into the curve segment of the calibration curve corresponding to the target interval segment to obtain the real-time distance.

[0091] For example, the current frequency is Continuing with the above 16 preset distances as an example, the calibration frequencies corresponding to the 16 preset distances are , … , assuming exist arrive , then the target interval is the sixth interval; further, Substitute into the curve segment of the calibration curve corresponding to the 6th interval segment (in this case, the calibration curve is a piecewise function consisting of 15 segments).

[0092] It can be seen that in order to determine the real-time distance, the target interval segment of the real-time frequency on the calibration curve is first determined, and the real-time frequency is substituted into the curve segment of the calibration curve corresponding to the target interval segment to obtain the real-time height; thereby, the real-time height can be determined quickly and accurately, and the slight distance changes between the cutting head and the workpiece surface during the workpiece cutting process can be responded to at a faster speed.

[0093] See also Figure 4 , Figure 4 This is a schematic diagram of a module of a laser cutting head provided in an embodiment of the present application. The present application also provides a laser cutting head, the laser cutting head 400 comprising: a processor 401 , a memory 402 , a laser cutting head 403 and a capacitive sensor 404 .

[0094] The memory 402 stores computer program instructions, and when the computer program instructions are executed by the processor 401, the steps in the above-mentioned calibration method and / or distance measurement method are executed.

[0095] Based on the same inventive concept, an embodiment of the present application also provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are read and executed by a processor, the steps in the above-mentioned calibration method and / or distance measurement method are executed.

[0096] The computer-readable storage medium may be a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or any other medium that can store program code.

[0097] In this article, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0098] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A calibration method, It is characterized in that The method comprises: Controlling the laser cutting head of the laser cutting machine to move n preset distances in sequence from the calibration workpiece surface to a direction away from the calibration workpiece surface, and obtaining n calibration frequencies and n calibration distances corresponding to the n preset distances; wherein n is greater than 1, the calibration distance is the distance between the laser cutting head and the calibration workpiece surface, and the calibration frequency is the frequency measured by the capacitive sensor in the laser cutting machine; Determine a conversion relationship for converting the calibration frequency to a corresponding frequency on a basic curve; wherein the basic curve reflects the relationship between the distance and frequency between a preset laser cutting head and a preset workpiece surface; wherein the determination of the conversion relationship for converting the calibration frequency to a corresponding frequency on the basic curve comprises: substituting each calibration distance into the basic curve to obtain a basic frequency corresponding to each calibration distance in the basic curve, and obtaining a total of n basic frequencies; dividing the basic curve into n-1 intervals with every two adjacent basic frequencies as endpoints; calculating the relationship between the basic frequency and the calibration frequency in each of the n-1 intervals to obtain n-1 conversion relationships corresponding to the n-1 intervals; The relationship between each of the basic frequencies and the calibration frequency is substituted into the basic curve to obtain a calibration curve.

2. The method according to claim 1, It is characterized in that Calculating the relationship between the basic frequency and the calibration frequency in the m-th interval segment of the n-1 interval segments to obtain the m-th conversion relationship corresponding to the m-th interval segment, including: Get the mth calibration frequency f m and the mth fundamental frequency f′ m , the composition point (f m , f′ m ); Get the m+1th calibration frequency f m+1 and the m+1th fundamental frequency f′ m+1 , the composition point (f m+1 , f′ m+1 ); The point (f m , f′ m ) and point (f m+1 , f′ m+1 ) is substituted into the conversion relationship F′=aF+b to determine the conversion coefficients a and b; Here, m is greater than or equal to 1 and less than or equal to n-1.

3. The method according to claim 1, It is characterized in that The method further comprises: Using the conversion relationship corresponding to the first interval segment after the calibration frequency is stabilized as the conversion relationship corresponding to at least one interval segment before the calibration frequency is stabilized; and / or The conversion relationship of the n-1th interval segment is used as the conversion relationship corresponding to at least one interval segment in which the calibration frequency does not change with the calibration distance; wherein the n-1th interval segment is the last interval segment in which the calibration frequency changes with the calibration distance.

4. The method according to claim 1, It is characterized in that The preset distance increases as the calibrated distance increases.

5. A distance measurement method, It is characterized in that The distance measurement method comprises: Controlling the laser cutting head of the laser cutting machine to move from the current workpiece surface to a cutting distance in a direction away from the current workpiece surface, and obtaining a real-time frequency corresponding to the cutting distance; wherein the cutting distance is the distance between the laser cutting head and the current workpiece surface, and the real-time frequency is the frequency measured by the capacitive sensor in the laser cutting machine; Substituting the real-time frequency into a calibration curve to obtain a real-time distance between the laser cutting head and the current workpiece surface; wherein the calibration curve represents the relationship between the frequency measured by the capacitive sensor and the distance between the laser cutting head and the current workpiece surface; Wherein, the calibration curve is determined based on the calibration method described in any one of claims 1-4.

6. The method according to claim 5, It is characterized in that The step of bringing the real-time frequency into a calibration curve to obtain a real-time distance between the laser cutting head and the current workpiece surface includes: Determine a target interval segment of the real-time frequency on the calibration curve; wherein the calibration curve is a piecewise curve; The real-time frequency is brought into the curve segment of the calibration curve corresponding to the target interval segment to obtain the real-time altitude.

7. A laser cutting machine, It is characterized in that Includes: laser cutting head, capacitive sensor, memory and processor; The memory stores computer program instructions, and when the computer program instructions are executed by the processor, the steps in the method according to any one of claims 1 to 6 are executed.

8. A computer-readable storage medium, It is characterized in that The computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the steps in the method according to any one of claims 1 to 6 are executed.

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