Height adjusting method and device of laser cutting head and laser processing device

Abstract

The invention discloses a height adjusting method and device for a laser cutting head and a laser machining device. The method comprises the steps that the initial calibration relation between the distance between the cutting head and a workpiece and the frequency is obtained; based on the initial calibration relation, the cutting head is controlled to move to a safe height, and a first reference frequency is obtained; the workpiece is machined on the basis of the initial calibration relation, the cutting head is controlled to move to the safe height again after a first set time after machining is started, and a second reference frequency is obtained; compensating the initial calibration relation based on the first reference frequency and the second reference frequency to generate an updated calibration relation; and switching to the updated calibration relation, and determining the distance between the cutting head and the workpiece according to the collected real-time frequency. According to the technical scheme provided by the invention, the measurement error generated by the distance measuring capacitor along with temperature drift can be reduced.

Description

Technical Field

[0001] This invention relates to the field of laser cutting technology, and in particular to a method, apparatus, and laser processing device for adjusting the height of a laser cutting head. Background Technology

[0002] In laser processing, it is generally necessary to detect the distance between the nozzle of the cutting head and the workpiece by detecting changes in the capacitance of the plate, so as to perform height tracking during the cutting process.

[0003] The capacitance of a parallel-plate capacitor's detection link typically includes: the parallel-plate capacitance from the nozzle to the workpiece, the parasitic capacitance of the entire link from the nozzle to the capacitor amplifier, and the component capacitance of the capacitor amplifier module. The parasitic capacitance and component capacitance are collectively referred to as the body capacitance. The parallel-plate capacitance from the nozzle to the workpiece can also be called the ranging capacitance. The ranging capacitance can be calculated by subtracting the body capacitance from the measured total capacitance of the detection link. However, during the cutting process, as the cutting head temperature rises, the body capacitance (especially the parasitic capacitance) changes, leading to measurement errors in the ranging capacitance. This error directly affects the control accuracy of the nozzle follow-up height, ultimately resulting in a decrease in cutting performance. Summary of the Invention

[0004] This invention provides a method, apparatus, and laser processing device for adjusting the height of a laser cutting head, thereby reducing measurement errors caused by temperature drift of the ranging capacitor and improving the control accuracy of the cutting head's follow-up height.

[0005] In a first aspect, embodiments of the present invention provide a method for adjusting the height of a laser cutting head, comprising: S1. Obtain the initial calibration relationship between the distance and frequency between the cutting head and the workpiece; S2. Based on the initial calibration relationship, control the cutting head to move to a safe height and obtain the first reference frequency; S3. Based on the initial calibration relationship, process the workpiece, and after a first set time after the start of processing, control the cutting head to move to the safe height again and obtain the second reference frequency; S4. Based on the first reference frequency and the second reference frequency, compensate the initial calibration relationship to generate an updated calibration relationship; S5. Switch to the updated calibration relationship and determine the distance between the cutting head and the workpiece based on the collected real-time frequency.

[0006] As a preferred embodiment, obtaining the initial calibration relationship between the distance and frequency between the cutting head and the workpiece includes: The cutting head is controlled to move away from the workpiece by a step interval d; At each step position, the corresponding measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; The initial calibration relationship is formed based on each step position and its corresponding measurement frequency.

[0007] As a preferred embodiment, forming the initial calibration relationship based on each step position and its corresponding measurement frequency includes: Record N consecutive step positions and their corresponding N measurement frequencies to form an initial calibration relationship array; The initial calibration relationship is obtained based on the initial calibration relationship array.

[0008] As a preferred embodiment, obtaining the corresponding measurement frequency at each step position via a capacitor amplifier electrically connected to the cutting head includes: According to the first reference frequency The total inductance L and total capacitance of the capacitor amplifier Obtain the initial body capacitance of the cutting head. ; According to the initial body capacitance of the cutting head and the initial calibration relation array Obtain the ranging capacitor array composed of ranging capacitors. ; The initial body capacitance of the cutting head is The ranging capacitor array is ; Wherein, the first reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

[0009] As a preferred embodiment, the initial calibration relationship is compensated based on the first reference frequency and the second reference frequency to generate an updated calibration relationship, including: The cutting head is controlled to move away from the workpiece by a step interval d; At each step position, the corresponding updated measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; the body capacitance of the cutting head is updated according to the second reference frequency. Based on each step position and its corresponding update measurement frequency, the initial calibration relationship is compensated to form an updated calibration relationship.

[0010] As a preferred embodiment, an update calibration relationship is formed based on each step position and its corresponding update measurement frequency, including: Record N consecutive step positions and their corresponding N update measurement frequencies to form an update calibration relationship array; The update calibration relationship is obtained based on the update calibration relationship array.

[0011] As a preferred embodiment, at each step position, the corresponding update measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head, including: According to the second reference frequency The total inductance L and total capacitance of the capacitor amplifier Obtain the updated body capacitor of the cutting head. ; According to the updated body capacitor of the cutting head A range-measuring capacitor array consisting of a range-measuring capacitor and a range-measuring capacitor. Get updated calibration relationship data group ; The updating body capacitor of the cutting head is The updated calibration relationship data group is , Wherein, the second reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

[0012] As a second aspect of this application, a height adjustment device for a laser cutting head is also provided, comprising: a controller, a cutting head that can be driven by a servo driver, a capacitor amplifier, and a first wiring connection connecting the capacitor amplifier and the cutting head; The controller acquires the initial calibration relationship between the distance and frequency between the cutting head and the workpiece; The controller is electrically connected to the servo driver and the capacitor amplifier respectively, and is used to control the cutting head to move to a safe height through the servo driver based on the initial calibration relationship, and to obtain the first reference frequency through the capacitor amplifier; The controller is also used to process the workpiece based on the initial calibration relationship, and after a first set time after the start of processing, control the cutting head to move back to the safe height and obtain the second reference frequency; The controller is also used to compensate the initial calibration relationship based on the first reference frequency and the second reference frequency to generate an updated calibration relationship; and switch to the updated calibration relationship to determine the distance between the cutting head and the workpiece according to the collected real-time frequency.

[0013] As a preferred embodiment, the capacitor amplifier includes an LC resonant circuit; The detection capacitance includes the sum of the body capacitance, the capacitance of the capacitor amplifier, and the distance measuring capacitance between the cutting head and the workpiece. The body capacitor includes the parasitic capacitance of the first wiring.

[0014] As a third aspect of this application, a laser processing apparatus is also proposed, including the aforementioned height adjustment device.

[0015] In this invention, the distance between the cutting head and the workpiece is controlled, and an initial calibration relationship between the stepping position and the measurement frequency is obtained through a detection circuit. Then, the cutting head is moved along the main shaft to a safe height, and a first reference frequency for the safe height is obtained (at which point the ranging capacitance is zero). Based on the first reference frequency and the measurement frequency in the initial calibration relationship, the ranging capacitance at different stepping positions is obtained. Because the body capacitance changes as the cutting head temperature increases, but the ranging capacitance does not change, this embodiment can process the workpiece for a period of time according to the initial calibration relationship. At a first set time after processing begins, a second reference frequency for the safe height is obtained again, and based on the second and first reference frequencies, the precise measurement frequency corresponding to the stepping position under the current temperature environment is obtained (the capacitance amplifier converts the detection capacitance into the measurement frequency), thereby obtaining a corrected updated calibration relationship. In this embodiment, the body capacitance after temperature drift is dynamically calculated, and the frequency-height calibration relationship is updated, so that the temperature drift compensation adapts to the nonlinear characteristics of the ranging capacitance, thereby improving the accuracy of the compensation algorithm. The precise distance between the cutting head and the workpiece is obtained from the updated calibration relationship based on the collected real-time measurement frequency, thus facilitating the acquisition of the precise position of the cutting head and improving its cutting performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a laser cutting head height adjustment device provided in an embodiment of the present invention; Figure 2 The circuit topology diagram of the detection system provided in the embodiment of the present invention; Figure 3 A schematic flowchart illustrating a method for adjusting the height of a laser cutting head according to an embodiment of the present invention; Figure 4 A schematic flowchart illustrating another method for adjusting the height of a laser cutting head provided in an embodiment of the present invention; Figure 5 The logic diagram of the compensation algorithm provided in the embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0018] The detection system measures the total capacitance of the link, which includes the sum of the body capacitance and the ranging capacitance. During testing, the relationship between the total capacitance and the distance (the distance from the cutting head nozzle to the workpiece) needs to be calibrated. After calibration, the size of the body capacitance needs to be recorded. The body capacitance should not change throughout the test; the difference between the total capacitance and the body capacitance is the ranging capacitance. However, as the cutting head nozzle temperature increases, the actual body capacitance is no longer the calibrated value. Calculating the ranging capacitance based on the difference between the calibrated total capacitance and the body capacitance will introduce errors.

[0019] The current compensation method in the industry is as follows: after calibration, the capacitance of the device is collected once, and then collected again after a certain period of time. The difference between the total capacitance collected after temperature drift and the calibrated capacitance is calculated, and then the difference is shifted and compensated with the capacitance value corresponding to each height in the calibration relationship. However, the calibration relationship is not linear (the ranging capacitance and the distance are inversely proportional, more like a hyperbola). This method compensates for the capacitance at each height by the same value, resulting in a coarse restoration of the actual capacitance frequency at each height.

[0020] This invention provides a height adjustment device for a laser cutting head, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a height adjustment device for a laser cutting head provided in an embodiment of the present invention. The height adjustment device may include: a controller 16, a cutting head 11 driven by a servo driver 17, a capacitor amplifier 14, and a first wiring 13 connecting the capacitor amplifier 14 and the cutting head 11; the controller 16 acquires an initial calibration relationship between the distance and frequency between the cutting head 11 and the workpiece; the controller 16 is electrically connected to the servo driver 17 and the capacitor amplifier 14 respectively, and is used to control the cutting head 11 to move to a safe height via the servo driver 17 based on the initial calibration relationship, and acquire a first reference frequency via the capacitor amplifier 14; the controller 16 is also used to process the workpiece 21 based on the initial calibration relationship, and after a first set time after the start of processing, control the cutting head 11 to move to a safe height again, and acquire a second reference frequency; the controller 16 is also used to compensate for the initial calibration relationship based on the first and second reference frequencies, generate an updated calibration relationship; and switch to the updated calibration relationship to determine the distance between the cutting head 11 and the workpiece based on the acquired real-time frequency.

[0021] In some embodiments, the calibration relationship can be expressed as a calibration curve with frequency and distance as the horizontal and vertical axes, respectively.

[0022] In some embodiments, the cutting head 11 is fixedly mounted on the machine tool spindle backplate 18, and the servo driver 17 drives the machine tool spindle backplate 18 to move along the spindle. Specifically, the controller 16 controls the servo driver 17 to drive the machine tool spindle backplate 18 to move along the spindle; the cutting head 11 is fixed on the machine tool spindle backplate 18, and the controller controls the cutting head 11 to move stepwise along the spindle until the cutting head 11 contacts the workpiece 21; the spindle is perpendicular to the contact surface between the cutting head 11 and the workpiece; the capacitor amplifier 14 is electrically connected to the cutting head 11 through the first wiring 13, and is used to convert the detection capacitance into a measurement frequency and send it to the controller 16; the controller 16 is also used to control the cutting head 11 to move away from the workpiece 21 along the spindle at step intervals, and The controller 16 is used to obtain the initial calibration relationship between the step position and the measurement frequency; the controller 16 is also used to control the cutting head 11 to move along the spindle to a safe height to obtain the first reference frequency of the safe height; and to obtain the distance measurement capacitance at different step positions according to the first reference frequency and the measurement frequency; the safe height is the distance between the cutting head 11 and the workpiece 21 where the distance measurement capacitance is zero; the controller 16 is also used to obtain the second reference frequency of the cutting head 11 at the safe height after a first set time; and to obtain the updated calibration relationship between the step position and the updated measurement frequency according to the second reference frequency and the first reference frequency (distance measurement capacitance).

[0023] The cutting head 11 (cutting head nozzle) is used to cut the surface of the workpiece, thereby processing the workpiece. The cutting head 11 acts as one plate of a ranging capacitor, and the workpiece acts as the other plate, thus forming a ranging capacitor between the cutting head 11 and the workpiece, with a gap 12 between them. The cutting head 11 and the capacitor amplifier 14 are electrically connected via a first wiring 13, which has parasitic capacitance. Optionally, the capacitor amplifier 14 may include an LC resonant circuit; the detection capacitor may include the body capacitor and the ranging capacitor between the cutting head 11 and the workpiece; the body capacitor may include the parasitic capacitance of the first wiring 13. The detection capacitor of the capacitor amplifier 14 may include the body capacitor of the cutting head 11 (including the parasitic capacitance of the first wiring 13, which varies significantly with temperature rise, affecting the value of the body capacitor), the total capacitance of the capacitor amplifier 14, and the ranging capacitor between the cutting head 11 and the workpiece. Figure 2 As shown, Figure 2This is a circuit topology diagram of the detection system provided in an embodiment of the present invention. C0 is the total capacitance of capacitor amplifier 14; L is the total inductance of capacitor amplifier 14; CS is the body capacitor; CP is the ranging capacitor. The total capacitance C0, body capacitor CS, and ranging capacitor CP of capacitor amplifier 14 are converted into a frequency signal (measurement frequency) by capacitor amplifier 14. The frequency signal is input to controller 16 for resonant frequency measurement. Controller 16 controls servo driver 17 to move the spindle via bus, and controls machine tool spindle backplate 18 to move along the spindle via servo driver 17, so that machine tool spindle backplate 18 drives cutting head 11 to move along the spindle. Controller 16 establishes a calibration relationship and obtains the distance (height) between cutting head 11 and workpiece 21 according to the measurement frequency corresponding to cutting head 11, and adjusts the current cutting height of cutting head 11 in real time to maintain a constant cutting height for cutting operations, thereby improving the cutting performance of cutting head.

[0024] During the height adjustment of the laser cutting head, the controller 16 first controls the cutting head 11 to move slowly or stepwise along the spindle axis towards the workpiece 21 via the servo driver 17, so that the cutting head 11 contacts the workpiece 21. The spindle axis can be perpendicular to the contact surface between the cutting head 11 and the workpiece 21. Then, the cutting head 11 is controlled to move in steps along the spindle axis away from the workpiece 21 at a step interval d. Each time it moves to a step position, the measurement frequency is obtained through the capacitor amplifier 14, thus obtaining the initial calibration relationship between the step position and the measurement frequency. After obtaining the initial calibration relationship, the step position is set to a safe height (the influence of the ranging capacitor can be ignored), and the standard body capacitor can be obtained (the capacitor amplifier 14 converts this to the first reference frequency). Since the ranging capacitance does not change with temperature drift, this embodiment obtains the ranging capacitance through an initial calibration relationship. After a period of time (the first set time, set according to the actual process cutting effect requirements), the capacitance drifts due to temperature rise. Then, the second reference frequency of the cutting head 11 at a safe height (the body capacitance after temperature drift) is measured again. Based on the ranging capacitance and the remeasured second reference frequency, the updated step position-measurement frequency calibration relationship is obtained. That is, the calibration relationship is updated, which makes it easier to determine the specific step position based on the measurement frequency output by the capacitor amplifier 14, thereby determining the distance between the cutting head 11 and the workpiece 21, which facilitates the improvement of the accurate detection of the height of the cutting head 11.

[0025] This embodiment, based on existing compensation technologies, utilizes the working principle of a capacitor amplifier hardware oscillation circuit and combines it with data collected during calibration. It dynamically calculates the body capacitance after temperature drift and updates the calibration relationship at each height (step position), adapting the temperature drift compensation to the nonlinear characteristics of the ranging capacitor. An algorithm calculates the capacitor frequency at each height after temperature drift, thereby improving the accuracy of the compensation algorithm. This application solves the problems of insufficient accuracy in existing technologies due to nonlinear calibration relationships and fixed-difference compensation.

[0026] In this embodiment, the distance between the cutting head and the workpiece is controlled, and an initial calibration relationship between the stepping position and the measurement frequency is obtained through a detection circuit. Then, the cutting head is moved along the main shaft to a safe height, and a first reference frequency for the safe height is obtained (at which point the ranging capacitance is zero). Based on the first reference frequency and the measurement frequency in the initial calibration relationship, the ranging capacitance at different stepping positions is obtained. Because the body capacitance changes as the cutting head temperature increases, but the ranging capacitance does not change, this embodiment can process the workpiece for a period of time according to the initial calibration relationship. At a first set time after processing begins, a second reference frequency for the safe height is obtained again, and based on the second and first reference frequencies, the precise measurement frequency corresponding to the stepping position under the current temperature environment is obtained (the capacitor amplifier converts the detection capacitance into the measurement frequency), thereby obtaining the corrected updated calibration relationship. In this embodiment, the body capacitance after temperature drift is dynamically calculated, and the calibration relationships for each height are updated, so that the temperature drift compensation adapts to the nonlinear characteristics of the ranging capacitance, thereby improving the accuracy of the compensation algorithm. The precise distance between the cutting head and the workpiece is obtained from the updated calibration relationship based on the collected real-time measurement frequency, thus facilitating the acquisition of the precise position of the cutting head and improving its cutting performance.

[0027] Based on the same concept, embodiments of the present invention provide a method for adjusting the height of a laser cutting head; Figure 3 This is a flowchart illustrating a method for adjusting the height of a laser cutting head according to an embodiment of the present invention, as shown below. Figure 3 As shown, the method in this embodiment includes the following steps: Step S1: Obtain the initial calibration relationship between the distance and frequency between the cutting head and the workpiece.

[0028] When measuring and obtaining the initial calibration relationship, the cutting head needs to contact the workpiece (collision plate) to gradually adjust the stepping position to obtain the measurement frequency. When controlling the contact between the cutting head and the workpiece, the cutting head needs to be controlled to descend slowly along the spindle to avoid damage to the workpiece contact surface. This embodiment uses a stepping movement method to effectively reduce the contact between the cutting head and the workpiece.

[0029] Optionally, obtaining the initial calibration relationship between the distance and frequency between the cutting head and the workpiece includes: controlling the cutting head to move away from the workpiece by a step interval d; at each step position, obtaining the corresponding measurement frequency through a capacitor amplifier electrically connected to the cutting head; and forming an initial calibration relationship based on each step position and its corresponding measurement frequency.

[0030] Each time, the cutting head moves a step distance d along the spindle axis away from the workpiece to the corresponding step position, and the measurement frequency is acquired through a capacitor amplifier electrically connected to the cutting head. Optionally, based on each step position and its corresponding measurement frequency, an initial calibration relationship is formed, including: recording N consecutive step positions and their corresponding N measurement frequencies to form an initial calibration relationship array; and obtaining the initial calibration relationship based on the initial calibration relationship array. The measurement frequencies of the N step positions constitute the initial calibration relationship array. N is a positive integer; the initial calibration relationship between step position and measurement frequency is obtained based on the initial calibration relationship array. For example, if d = 0.1 mm, a total of N = 200 step positions are formed from 0.1 mm to 20 mm, and the measurement frequencies of N step positions constitute the initial calibration relationship array. In this embodiment, The N measurement frequencies are arranged sequentially on a plane with the step position on the horizontal axis and the measurement frequency on the vertical axis to form the initial calibration relationship.

[0031] Step S2: Based on the initial calibration relationship, control the cutting head to move to a safe height and obtain the first reference frequency.

[0032] like Figure 1 and Figure 2 As shown, the cutting head continuously rises along the main axis to a safe height. When the cutting head moves to the safe height along the main axis, the ranging capacitor CP is negligible. At this point, the capacitor amplifier can obtain the first reference frequency. According to the formula The initial body capacitance of the cutting head can be calculated. The sum of the capacitances of the capacitor amplifier The summation of these values ​​allows us to obtain the initial body capacitance of the cutting head. Then, based on the initial calibration relationship and the initial body capacitance To obtain the ranging capacitors at different step positions, it's important to note that since there are N step positions, N ranging capacitors will be measured corresponding to different step positions, and these N ranging capacitors will form a ranging capacitor array. .

[0033] Wherein, the first reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

[0034] Step S3: Process the workpiece based on the initial calibration relationship, and after the first set time after the start of processing, control the cutting head to move to a safe height again and obtain the second reference frequency.

[0035] Step S4: Based on the first reference frequency and the second reference frequency, compensate for the initial calibration relationship and generate an updated calibration relationship.

[0036] Since temperature rise has no effect on the ranging capacitance, the ranging capacitance measured at the same step position in both the initial calibration and the updated calibration relationships is the same. This embodiment allows for the remeasurement of the second reference frequency after a first set time period of temperature drift. According to the second reference frequency The sum of the capacitances of the main capacitor, ranging capacitor, and capacitor amplifier can be calculated using the ranging capacitor (obtained based on the first reference frequency). The total capacitance (test frequency) is used to obtain an updated calibration relationship array for N measurement frequencies. The N measurement frequencies are arranged sequentially on a plane where the horizontal axis represents the step position and the vertical axis represents the measurement frequency, forming an update calibration relationship. It should be noted that the first set time can be set according to the cutting process effect; this embodiment does not impose any special limitations on this.

[0037] Wherein, the second reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

[0038] Step S5: Switch to update calibration relationship and determine the distance between the cutting head and the workpiece based on the collected real-time frequency.

[0039] The update calibration relationship is an array of update calibration relationships between step position and test frequency under the current temperature environment. The resulting curve. Under the current temperature environment, the step position is obtained from the updated calibration relationship based on the real-time acquisition frequency, thereby obtaining the current frequency to determine the distance between the cutting head and the workpiece, improving the accuracy of the cutting head position measurement.

[0040] In this embodiment of the invention, the distance between the cutting head and the workpiece is controlled, and an initial calibration relationship between the stepping position and the measurement frequency is obtained through a detection circuit. Then, the cutting head is moved along the main shaft to a safe height, and a first reference frequency for the safe height is obtained (at which point the ranging capacitance is zero). Based on the first reference frequency and the measurement frequency in the initial calibration relationship, the ranging capacitance at different stepping positions is obtained. Because the body capacitance changes as the cutting head temperature increases, but the ranging capacitance does not change, this embodiment can process the workpiece for a period of time according to the initial calibration relationship. At a first set time after processing begins, a second reference frequency for the safe height is obtained again, and based on the second reference frequency and the first reference frequency, the precise measurement frequency corresponding to the stepping position under the current temperature environment is obtained (the capacitance amplifier converts the detection capacitance into the measurement frequency), thereby obtaining the corrected updated calibration relationship. In this embodiment, the body capacitance after temperature drift is dynamically calculated and the calibration relationships for each height are updated, so that the temperature drift compensation adapts to the nonlinear characteristics of the ranging capacitance, thereby improving the accuracy of the compensation algorithm. The precise distance between the cutting head and the workpiece is obtained from the updated calibration relationship based on the collected real-time measurement frequency, thus facilitating the acquisition of the precise position of the cutting head and improving its cutting performance. This embodiment dynamically calculates the body capacitance after temperature drift and updates the calibration relationships of each height, which helps to improve the control accuracy of the nozzle follow-up height of the cutting head, reduce errors, and thus help to ensure the cut quality and processing stability of laser cutting. The reliability of laser cutting is greatly improved. The technical solution of this application solves the problem of insufficient compensation accuracy in the prior art.

[0041] The above is the core idea of ​​this invention. The technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] Based on the above embodiments, at each step position, obtaining the corresponding measurement frequency through a capacitor amplifier electrically connected to the cutting head includes: according to a first reference frequency. The total inductance L and total capacitance of the capacitor amplifier Obtain the initial body capacitance of the cutting head. Based on the initial body capacitance of the cutting head and the initial calibration relation array Obtain the ranging capacitor array composed of ranging capacitors. .

[0043] In another embodiment, the process of "obtaining the corresponding measurement frequency at each step position through a capacitor amplifier electrically connected to the cutting head" during the initial calibration relationship calibration process is described in detail, and the process of obtaining the ranging capacitor and the updated calibration relationship of step position-measurement frequency is also described in detail, specifically as follows: Figure 4 As shown, Figure 4 This is a flowchart illustrating another method for adjusting the height of a laser cutting head according to an embodiment of the present invention. The method of this embodiment includes the following steps: Step S201: Control the cutting head to move away from the workpiece by a step interval d.

[0044] The cutting head is controlled to move stepwise along the spindle until it contacts the workpiece; the spindle is perpendicular to the contact surface between the cutting head and the workpiece. Optionally, "obtaining the initial calibration relationship of distance and frequency between the cutting head and the workpiece" may include the contents of steps S201 to S203.

[0045] Step S202: At each step position, the corresponding measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head.

[0046] Each time, the cutting head is moved along the spindle axis away from the workpiece by a step distance d to the corresponding step position, and the measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; the measurement frequencies of N step positions constitute the initial calibration relationship array. N is a positive integer; the initial calibration relationship between step position and measurement frequency is obtained based on the initial calibration relationship array. This embodiment uses the initial calibration relationship array... Let's take an example to illustrate. For example... Figure 5 As shown, Figure 5 This is a logic diagram of the compensation algorithm provided in an embodiment of the present invention. An initial calibration relationship array is obtained through the initial calibration relationship. .

[0047] Optionally, at each step position, the corresponding measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head, including: based on a first reference frequency. The total inductance L and total capacitance of the capacitor amplifier Obtain the initial body capacitance of the cutting head. Based on the initial body capacitance of the cutting head and the initial calibration relation array Obtain the ranging capacitor array composed of ranging capacitors. The initial body capacitance of the cutting head is The ranging capacitor array is .

[0048] Optionally, the initial body capacitance of the cutting head is This embodiment continues to obtain the first reference frequency by raising the cutting head to a safe height. At this point, the ranging capacitor CP does not exist, so the capacitance only includes the initial body capacitance of the cutting head and the total capacitance. Therefore, the initial capacitance of the cutting head is... .

[0049] Optionally, the ranging capacitor array is Based on this, the ranging capacitance array for 200 step positions (elevation points) can be calculated. . That is, The main process involves subtracting the initial body capacitance sequentially from the measurement frequency in the initial calibration relationship. Sum of capacitance The ranging capacitors are obtained, and N ranging capacitors form a ranging capacitor array. .

[0050] Step S203: Based on each step position and its corresponding measurement frequency, an initial calibration relationship is formed.

[0051] Step S204: Based on the initial calibration relationship, control the cutting head to move to a safe height and obtain the first reference frequency.

[0052] After obtaining the initial calibration relationship, the step position is set to a safe height (the influence of the ranging capacitor can be ignored), and the standard body capacitor can be obtained (converted to the first reference frequency by the capacitor amplifier). Since the ranging capacitor does not change with temperature drift, this embodiment obtains the ranging capacitor through the initial calibration relationship; after a period of time (the first set time, set according to the actual process cutting effect requirements), the capacitor experiences temperature drift after the temperature rises. Then, the second reference frequency of the cutting head at the safe height (the body capacitor after temperature drift) is measured again. Based on the ranging capacitor and the remeasured second reference frequency, the updated step position-measurement frequency calibration relationship is obtained.

[0053] Step S205: Process the workpiece based on the initial calibration relationship, and after the first set time after the start of processing, control the cutting head to move to a safe height again and obtain the second reference frequency.

[0054] Step S206: Control the cutting head to move away from the workpiece by a step interval d.

[0055] "Based on the first reference frequency and the second reference frequency, the initial calibration relationship is compensated to generate an updated calibration relationship" includes the contents of steps S206 to S208.

[0056] Step S207: At each step position, the corresponding update measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; the body capacitance of the cutting head is updated according to the second reference frequency.

[0057] Optionally, at each step position, the corresponding updated measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head, including: based on a second reference frequency. The total inductance L and total capacitance of the capacitor amplifier Get the updated body capacitor of the cutting head. ; Update the body capacitor according to the cutting head A range-measuring capacitor array consisting of a range-measuring capacitor and a range-measuring capacitor. Get updated calibration relationship data group The replacement capacitor of the cutting head is... Update the calibration relation data group to .

[0058] Obtain the second reference frequency when temperature drift compensation is required. The capacitor for updating the cutting head. With initial body capacitance = The difference is mainly due to the parasitic capacitance of the first wiring. Optionally, the replacement capacitance of the cutting head body is... At this point, since there is no ranging capacitor CP, the capacitor only includes the update body capacitor of the cutting head. Sum of capacitance Therefore, the initial capacitance of the cutting head is... .

[0059] Optionally, update the calibration relation array as follows: At this point, the total capacitance is the sum of the capacitance of the main body capacitor, the ranging capacitor, and the capacitance amplifier. Given that all parameters are known, each measurement frequency can be calculated, and the updated calibration relationship array can be obtained. , that is, .

[0060] Step S208: Based on each step position and its corresponding update measurement frequency, compensate for the initial calibration relationship to form an updated calibration relationship.

[0061] Similarly, based on each step position and its corresponding update measurement frequency, an update calibration relationship is formed, including: recording N consecutive step positions and their corresponding N update measurement frequencies to form an update calibration relationship array; obtaining the update calibration relationship based on the update calibration relationship array. The update calibration relationship between step position and measurement frequency is obtained based on the update calibration relationship array. In the above example, the update calibration relationship array... This forms a new updated calibration relationship.

[0062] As a third aspect of this application, a laser processing apparatus is also proposed, including the aforementioned height adjustment device.

[0063] In this embodiment, by dynamically calculating the body capacitance after temperature drift and updating the frequency-height calibration relationship, it is beneficial to improve the control accuracy of the nozzle follow-up height, reduce errors, and thus help ensure the cut quality and processing stability of laser cutting. The reliability of laser cutting is greatly improved. The technical solution of this application solves the problem of insufficient compensation accuracy in the prior art.

[0064] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for adjusting the height of a laser cutting head, characterized in that, include: S1. Obtain the initial calibration relationship between the distance and frequency between the cutting head and the workpiece; S2. Based on the initial calibration relationship, control the cutting head to move to a safe height and obtain the first reference frequency; S3. Based on the initial calibration relationship, process the workpiece, and after a first set time after the start of processing, control the cutting head to move to the safe height again and obtain the second reference frequency; S4. Based on the first reference frequency and the second reference frequency, compensate the initial calibration relationship to generate an updated calibration relationship; S5. Switch to the updated calibration relationship and determine the distance between the cutting head and the workpiece based on the collected real-time frequency.

2. The height adjustment method according to claim 1, characterized in that, The initial calibration relationship for obtaining the distance and frequency between the cutting head and the workpiece includes: The cutting head is controlled to move away from the workpiece by a step interval d; At each step position, the corresponding measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; The initial calibration relationship is formed based on each step position and its corresponding measurement frequency.

3. The height adjustment method according to claim 2, characterized in that, The process of forming the initial calibration relationship based on each step position and its corresponding measurement frequency includes: Record N consecutive step positions and their corresponding N measurement frequencies to form an initial calibration relationship array; The initial calibration relationship is obtained based on the initial calibration relationship array.

4. The height adjustment method according to claim 2, characterized in that, The step of obtaining the corresponding measurement frequency at each step position through a capacitor amplifier electrically connected to the cutting head includes: According to the first reference frequency The total inductance L and total capacitance of the capacitor amplifier Obtain the initial body capacitance of the cutting head. ; According to the initial body capacitance of the cutting head and the initial calibration relation array Obtain the ranging capacitor array composed of ranging capacitors. ; The initial body capacitance of the cutting head is The ranging capacitor array is ; Wherein, the first reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

5. The height adjustment method according to claim 1, characterized in that, Based on the first reference frequency and the second reference frequency, the initial calibration relationship is compensated to generate an updated calibration relationship, including: The cutting head is controlled to move away from the workpiece by a step interval d; At each step position, the corresponding updated measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head; the body capacitance of the cutting head is updated according to the second reference frequency. Based on each step position and its corresponding update measurement frequency, the initial calibration relationship is compensated to form an updated calibration relationship.

6. The height adjustment method according to claim 5, characterized in that, Based on each step position and its corresponding update measurement frequency, an update calibration relationship is formed, including: Record N consecutive step positions and their corresponding N update measurement frequencies to form an update calibration relationship array; The update calibration relationship is obtained based on the update calibration relationship array.

7. The height adjustment method according to claim 5, characterized in that, At each step position, the corresponding updated measurement frequency is obtained through a capacitor amplifier electrically connected to the cutting head, including: According to the second reference frequency The total inductance L and total capacitance of the capacitor amplifier Obtain the updated body capacitor of the cutting head. ; According to the updated body capacitor of the cutting head A range-measuring capacitor array consisting of a range-measuring capacitor and a range-measuring capacitor. Get updated calibration relationship data group ; The updating body capacitor of the cutting head is The updated calibration relationship data group is , Wherein, the second reference frequency The unit is Hz, the unit of total inductance (L) is Henry, and the unit of total capacitance is... The unit is farad, and N is a positive integer.

8. A height adjustment device for a laser cutting head, characterized in that, include: The controller, the cutting head that can be driven by the servo driver, the capacitor amplifier, and the first wiring connecting the capacitor amplifier and the cutting head; The controller acquires the initial calibration relationship between the distance and frequency between the cutting head and the workpiece; The controller is electrically connected to the servo driver and the capacitor amplifier respectively, and is used to control the cutting head to move to a safe height through the servo driver based on the initial calibration relationship, and to obtain the first reference frequency through the capacitor amplifier; The controller is also used to process the workpiece based on the initial calibration relationship, and after a first set time after the start of processing, control the cutting head to move back to the safe height and obtain the second reference frequency; The controller is also configured to compensate the initial calibration relationship based on the first reference frequency and the second reference frequency, and generate an updated calibration relationship; Then switch to the updated calibration relationship and determine the distance between the cutting head and the workpiece based on the collected real-time frequency.

9. The height adjustment device according to claim 8, characterized in that, The capacitor amplifier includes an LC resonant circuit; The detection capacitance includes the sum of the body capacitance, the capacitance of the capacitor amplifier, and the distance measuring capacitance between the cutting head and the workpiece. The body capacitor includes the parasitic capacitance of the first wiring.

10. A laser processing apparatus, characterized in that, Includes the height adjustment device as described in claim 8.

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