Method for detecting the sag of a pipe to be cut and laser cutting apparatus

Abstract

The application provides a kind of detection method of pipe sag amount to be cut and laser cutting equipment, by the type of pipe to be cut, the bevel trajectory on the previous cutting trajectory and the face to be detected, the detection point corresponding to the bevel trajectory is determined;The face to be detected is upwards, and the laser cutting head is moved to the detection point above;By controlling the capacitive height adjuster, the actual Z-axis coordinate when the laser cutting head contacts the detection point is obtained;According to the absolute value of the difference between the actual Z-axis coordinate of the detection point and the theoretical Z-axis coordinate of the detection point, the sag amount of the bevel trajectory is obtained. Thus, the application selects the detection point corresponding to the bevel trajectory based on a variety of fusion information, so that the selection of the detection point is more in line with the actual situation of the pipe to be cut. On this basis, the application also improves the detection accuracy of the sag amount of the detection point by contact detection, thereby improving the detection accuracy of the sag amount of the pipe to be cut.

Description

Technical Field

[0001] This invention relates to the field of laser cutting technology, and in particular to a method for detecting the sag of a pipe to be cut and a laser cutting device. Background Technology

[0002] Laser cutting technology, with its high energy density, excellent cutting quality, and flexible CNC capabilities, has become the preferred process for achieving complex three-dimensional cutting.

[0003] However, during the laser cutting process, especially when cutting beveled trajectories, the weight of the pipe, the clamping force of the chuck, and the dynamic overhang relative to the chuck during processing often cause varying degrees of sagging or upturning deformation on each bevel trajectory on each surface to be probed. Therefore, it is difficult to accurately measure the amount of sagging in the pipe. Summary of the Invention

[0004] This invention provides a method for detecting the sag of a pipe to be cut and a laser cutting device, which improves the measurement accuracy of the sag of the pipe to be cut.

[0005] According to a first aspect of the present invention, the technical solution of the present invention provides a method for detecting the sagging of a pipe to be cut, comprising: Based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, the detection point corresponding to the bevel trajectory is determined, and the cutting order of the prior cutting trajectory is prior to the bevel trajectory. Position the surface to be detected upwards and move the laser cutting head above the detection point; The actual Z-axis coordinates when the laser cutting head contacts the detection point are obtained by controlling the capacitive height adjustment device; The sag of the bevel trajectory is obtained based on the absolute value of the difference between the actual Z-axis coordinate and the theoretical Z-axis coordinate of the detection point. The theoretical Z-axis coordinate is the Z-axis coordinate of the detection point when the pipe to be cut is in an ideal state without sag, and the Z-axis is perpendicular to the upward-facing detection surface.

[0006] Optionally, based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, the detection point corresponding to the bevel trajectory is determined, including: Based on the bevel trajectory, obtain all bevel points in the bevel trajectory; Based on the bevel trajectory on the surface to be detected, an ideal point is determined, which is the bevel point that is first cut by the bevel trajectory; Based on the type of pipe to be cut and the ideal point, determine the X-axis coordinate of the detection point; Based on the ideal point, the bevel trajectory, and the prior cutting trajectory, the Y-axis coordinate of the detection point is determined; wherein, the X-axis is perpendicular to the Y-axis and perpendicular to the Z-axis, the Y-axis is perpendicular to the Z-axis, and the Y-axis coordinate increases along the processing direction of the laser cutting head on the pipe to be cut, the processing direction being opposite to the extension direction of the pipe to be cut relative to the chuck.

[0007] Optionally, based on the bevel trajectory on the surface to be detected, the ideal point is determined, including: The type of the bevel trajectory is determined, and the type of the bevel trajectory includes front cut, rear cut, and tube hole; wherein, in the process of cutting the current part to be cut, the front cut is characterized as: the first bevel trajectory cut; the rear cut is characterized as: the last bevel trajectory cut; and the tube hole is characterized as: the bevel trajectory cut after the front cut and before the rear cut. If the type of the bevel trajectory is the front cut, then the ideal point is determined as the bevel point with the smallest Y-axis coordinate in the bevel trajectory; If the type of the bevel trajectory is post-cut or pipe face, then the ideal point is determined as the bevel point with the largest Y-axis coordinate in the bevel trajectory.

[0008] Optionally, based on the type of pipe to be cut and the ideal point, the X-axis coordinate of the detection point is determined, including: The X-axis coordinate of the retreat point with a first predicted distance from the specified edge line is determined as the X-axis coordinate of the detection point. The specified edge line is the edge line of the surface to be detected that is closest to the ideal point. The edge line of the surface to be detected extends along the Y-axis direction. The retreat point is a point located in the surface to be detected.

[0009] Optionally, determining the X-axis coordinate of the detection point based on the type of pipe to be cut and the ideal point further includes: If the type of pipe to be cut is shaped steel, round pipe, or the width of the surface to be detected along the X-axis is less than twice the first preset distance, the X-axis coordinate of the midpoint equidistant from the two preset edge lines is determined as the X-axis coordinate of the detection point. The two preset edge lines are the edge lines of the surface to be detected located on opposite sides of the surface to be detected along the X-axis, and the midpoint is a point located in the surface to be detected.

[0010] Optionally, determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory further includes: Based on the Y-axis machining range and the overall Y-axis machinable range of the bevel trajectory, the intersection of the Y-axis machining range and the overall Y-axis machinable range of the bevel trajectory is obtained. The Y-axis machining range of the bevel trajectory is the Y-axis coordinate range of the bevel trajectory on the surface to be detected, and the overall Y-axis machinable range is the Y-axis coordinate range of the surface to be detected after deleting the Y-axis coordinate range of the previously cut trajectory. Based on the intersection, the Y-axis coordinate of the detection point is determined.

[0011] Optionally, based on the intersection, determining the Y-axis coordinate of the detection point includes: Determine whether the intersection is empty; If the intersection is empty, then the Y-axis coordinate of the detection point is determined as the maximum Y-axis coordinate of the prior cutting trajectory; If the intersection is not empty, then the Y-axis coordinate of the bevel point in the intersection that has the smallest Y-axis coordinate distance from the ideal point along the Y-axis direction is determined as the Y-axis coordinate of the detection point.

[0012] Optionally, determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory further includes: If the bevel trajectory is a post-cut, then the Y-axis coordinate of the detection point is determined as the Y-axis coordinate of the ideal point, reduced by a second preset distance along the processing direction.

[0013] Optionally, obtaining the actual Z-axis coordinates when the laser cutting head contacts the detection point includes: The actual Z-axis coordinates of the laser cutting head when it sequentially contacts the detection point at several preset sway angles are obtained. The preset sway angle is characterized as the angle relative to the Z-axis.

[0014] According to a second aspect of the present invention, the technical solution of the present invention provides a laser cutting device for realizing the method for detecting the sag of the pipe to be cut as described above.

[0015] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects: In the method for detecting the sag of the pipe to be cut and the laser cutting equipment of this invention, the detection point corresponding to the bevel trajectory is determined based on the type of pipe to be cut, the previous cutting trajectory, and the bevel trajectory on the surface to be detected. The cutting sequence of the previous cutting trajectory precedes the bevel trajectory. The surface to be detected is facing upwards, and the laser cutting head is moved above the detection point. The actual Z-axis coordinate of the laser cutting head when it contacts the detection point is obtained by controlling a capacitive height adjuster. The sag of the bevel trajectory is obtained based on the absolute value of the difference between the actual Z-axis coordinate and the theoretical Z-axis coordinate of the detection point. The theoretical Z-axis coordinate is the Z-axis coordinate of the detection point when the pipe to be cut is in an ideal state without sag, and the Z-axis is perpendicular to the upward-facing surface to be detected. Thus, this invention selects the detection point corresponding to the bevel trajectory based on multiple fused information, making the selection of the detection point more consistent with the actual situation of the pipe to be cut. On this basis, this invention also improves the detection accuracy of the sag of the detection point by using a contact detection method, thereby improving the detection accuracy of the sag of the pipe to be cut. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the first process of a method for detecting the sagging of a pipe to be cut, provided in an embodiment of the present invention. Figure 2 This is a second flowchart illustrating a method for detecting the sagging of a pipe to be cut, provided in an embodiment of the present invention. Figure 3 This is a third flowchart illustrating a method for detecting the sagging of a pipe to be cut, provided in an embodiment of the present invention. Figure 4 This is a fourth flowchart illustrating a method for detecting the sagging of a pipe to be cut, provided in an embodiment of the present invention. Figure 5 This is the fifth flowchart of a method for detecting the sagging of a pipe to be cut, provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of the location of the detection point when the intersection is not empty in an embodiment of the present invention; Figure 7 This is a schematic diagram showing the location of the detection point when the intersection is empty in an embodiment of the present invention; Figure 8 This is a schematic diagram of the detection point location when the bevel trajectory is a post-cutting event in an embodiment of the present invention. Detailed Implementation

[0018] As described in the background section, the present invention aims to solve the technical problem of accurately detecting the sagging amount of the pipe to be cut.

[0019] In view of this, the present invention provides a method for detecting the sag of a pipe to be cut. Based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, a detection point corresponding to the bevel trajectory is determined, with the cutting sequence of the prior cutting trajectory preceding the bevel trajectory. The surface to be detected is facing upwards, and the laser cutting head is moved above the detection point. The actual Z-axis coordinates of the laser cutting head when contacting the detection point are obtained by controlling a capacitive height adjuster. The sag of the bevel trajectory is obtained based on the absolute value of the difference between the actual Z-axis coordinates and the theoretical Z-axis coordinates of the detection point. The theoretical Z-axis coordinates are the Z-axis coordinates of the detection point in an ideal state where the pipe to be cut is in a no-sag condition, and the Z-axis is perpendicular to the upward-facing surface to be detected. This method accurately detects the sag of the pipe to be cut and improves the measurement accuracy of the detection point.

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The terms “first,” “second,” “third,” and “fourth,” etc. (if present), in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0023] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Please refer to Figure 1 The present invention provides a method for detecting the sagging of a pipe to be cut, which may include: S100: Based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, determine the detection point corresponding to the bevel trajectory, wherein the cutting order of the prior cutting trajectory is prior to the bevel trajectory; S200: Position the surface to be detected upwards and move the laser cutting head above the detection point; S300: By controlling the capacitive height adjuster, the actual Z-axis coordinates when the laser cutting head contacts the detection point are obtained; S400: Based on the absolute value of the difference between the actual Z-axis coordinate and the theoretical Z-axis coordinate of the detection point, obtain the sag of the bevel trajectory. The theoretical Z-axis coordinate is the Z-axis coordinate of the detection point when the pipe to be cut is in an ideal state without sag, and the Z-axis is perpendicular to the upward-facing surface to be detected.

[0025] As an example, the type of pipe to be cut may include rectangular pipe, round pipe, and structural steel. The structural steel may be any one of C-shaped steel, L-shaped steel, and channel steel.

[0026] As can be seen, this invention selects the detection points corresponding to the bevel trajectory based on multiple fusion information, making the selection of detection points more consistent with the actual situation of the pipe to be cut. Furthermore, this invention improves the detection accuracy of the sagging amount of the detection points through contact detection, thereby improving the detection accuracy of the sagging amount of the pipe to be cut.

[0027] In this embodiment, the contact detection method controls the detection accuracy of the sag at the detection point to within ±0.05mm. Compared with the traditional non-contact follow-up detection (the error is usually greater than ±0.1mm), the measurement accuracy of the sag at the detection point is significantly improved, which can meet the requirements of micron-level deformation compensation in high-precision bevel cutting.

[0028] Please refer to Figure 2 As a specific implementation method, S100, based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, determines the detection point corresponding to the bevel trajectory, which may include: S110: Based on the bevel trajectory, obtain all bevel points in the bevel trajectory; S120: Based on the bevel trajectory on the surface to be detected, determine the ideal point, which is the bevel point where the bevel trajectory first cuts the bevel; S130: Determine the X-axis coordinate of the detection point based on the type of the pipe to be cut and the ideal point; S140: Based on the ideal point, the bevel trajectory, and the prior cutting trajectory, determine the Y-axis coordinate of the detection point; wherein, the X-axis is perpendicular to the Y-axis and perpendicular to the Z-axis, the Y-axis is perpendicular to the Z-axis, the Y-axis coordinate increases along the processing direction of the laser cutting head on the pipe to be cut, and the processing direction is opposite to the extension direction of the pipe to be cut relative to the chuck.

[0029] In this embodiment, the prior cutting trajectory refers to the cutting trajectory located on the surface to be detected, whose cutting order, i.e., processing order, precedes the bevel trajectory. When determining the detection point, the Y-axis coordinate range of prior cutting trajectories on other surfaces to be detected is first deleted, and only the prior cutting trajectory and bevel trajectory on the surface to be detected are considered.

[0030] In this embodiment, the X-axis coordinate and Y-axis coordinate of the detection point are determined based on the type of pipe to be cut and an ideal point. This ensures that the detection points are selectable and that they have a high spatial correlation with the bevel trajectory, so that the measured sag can more accurately reflect the actual sag state of the bevel trajectory at the actual processing position.

[0031] Please refer to Figure 3 As an optional implementation, S120, based on the bevel trajectory on the surface to be detected, determines the ideal point, including: S121: Determine the type of the bevel trajectory, which includes front cut, rear cut, and tube hole; wherein, during the cutting of the current part to be cut, the front cut is characterized as the first bevel trajectory cut; the rear cut is characterized as the last bevel trajectory cut; and the tube hole is characterized as the bevel trajectory cut after the front cut and before the rear cut. If the type of the bevel trajectory is the front cut, then proceed to S122: determine the ideal point as the bevel point with the smallest Y-axis coordinate in the bevel trajectory; If the type of the bevel trajectory is post-cut or pipe face, then proceed to S123: determine the ideal point as the bevel point with the largest Y-axis coordinate in the bevel trajectory.

[0032] In this embodiment, the selection of the ideal point ensures that the subsequent probe points adjusted based on the ideal point are highly correlated spatially with the bevel trajectory. This makes the selection of probe points more representative, so that the measured sag can more accurately reflect the true sag state of the bevel trajectory at the actual processing position.

[0033] In an optional implementation, S130, determining the X-axis coordinate of the detection point based on the type of pipe to be cut and the ideal point may include: S131: The X-axis coordinate of the retreat point with a first predicted distance from the specified edge line is determined as the X-axis coordinate of the detection point. The specified edge line is the edge line of the surface to be detected that is closest to the ideal point. The edge line of the surface to be detected extends along the Y-axis direction. The retreat point is a point located in the surface to be detected.

[0034] In this embodiment, the first predicted distance can be equal to the width of the laser cutting head along the X-axis direction. For example, the first predicted distance can be 8mm.

[0035] In this embodiment, the X-axis coordinates of the detection point determined by this method can prevent the laser cutting head from hitting the edge line of the surface to be detected along the X-axis direction during the detection process.

[0036] As another optional implementation, S130, determining the X-axis coordinate of the detection point based on the type of pipe to be cut and the ideal point may further include: S132: If the type of pipe to be cut is shaped steel, round pipe, or the width of the surface to be detected along the X-axis is less than twice the first preset distance, the X-axis coordinate of the midpoint equidistant from the two preset edge lines is determined as the X-axis coordinate of the detection point. The two preset edge lines are the edge lines of the surface to be detected located on opposite sides of the surface to be detected along the X-axis direction, and the midpoint is a point located in the surface to be detected.

[0037] In this embodiment, the midpoint along the X-axis on the surface of the round steel and shaped steel to be cut has better quality and is less prone to sagging. Therefore, for round steel or shaped steel, determining the X-axis coordinate of the detection point as the X-axis coordinate of the midpoint makes the measurement results of the present invention closer to the actual sagging state of the bevel trajectory, thereby improving the measurement accuracy of the sagging amount of the present invention.

[0038] In this embodiment, for a surface to be detected whose width along the X-axis direction is less than twice the first predicted distance, the X-axis coordinate of the detection point is determined as the X-axis coordinate of the midpoint. This can minimize the risk of the laser cutting head colliding with the two edge lines of the surface to be detected located on opposite sides of the surface along the X-axis direction during the detection process.

[0039] Please refer to Figure 4 As a specific implementation method, S140, determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory may further include: S141: Based on the Y-axis machining range of the bevel trajectory and the overall machinable range of the Y-axis, obtain the intersection of the Y-axis machining range of the bevel trajectory and the overall machinable range of the Y-axis, wherein the Y-axis machining range of the bevel trajectory is the Y-axis coordinate range of the bevel trajectory on the surface to be detected, and the overall machinable range of the Y-axis is the Y-axis coordinate range of the detection surface after deleting the Y-axis coordinate range of the previously cut trajectory on the surface to be detected; S142: Based on the intersection, determine the Y-axis coordinate of the detection point.

[0040] Please refer to Figure 5 As a specific implementation method, S142, determining the Y-axis coordinate of the detection point based on the intersection may include: S1421: Determine whether the intersection is empty; If the intersection is empty, proceed to S1422: determine the Y-axis coordinate of the detection point as the maximum Y-axis coordinate of the prior cutting trajectory; If the intersection is not empty, proceed to S1423: determine the Y-axis coordinate of the bevel point in the intersection that has the smallest Y-axis coordinate distance from the ideal point along the Y-axis direction as the Y-axis coordinate of the detection point.

[0041] In this embodiment, by determining whether there is an intersection between the bevel trajectory and the overall processing area, the detection point is intelligently selected to ensure that the sag measurement can be completed automatically and safely under any cutting state, avoiding the inability to detect because the detection point is not left on the actual surface of the pipe to be cut due to the processing of the previous processing trajectory.

[0042] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the location of the detection point when the intersection is non-empty in an embodiment of the present invention.

[0043] In such Figure 6 In the illustrated embodiment, the intersection is non-empty. By setting the Y-axis coordinate of the detection point A within the intersection, it avoids the possibility that the detection point A might not be present on the actual surface of the pipe to be cut due to prior processing of the machining trajectory, thus preventing detection. Furthermore, by determining the Y-axis coordinate of the detection point A as the Y-axis coordinate of the bevel point closest to the ideal point B along the Y-axis direction, the detection point A is maximized to be as close as possible to the ideal point B while avoiding the inability to detect the actual surface of the pipe to be cut. This allows the sag of the detection point on the bevel trajectory to more accurately reflect the true deformation state of the bevel trajectory position, providing a more effective real-time compensation benchmark for subsequent bevel trajectory cutting, and effectively improving processing accuracy and system response accuracy.

[0044] Please refer to point 7. Figure 7 This is a schematic diagram showing the location of the detection point when the intersection is empty in an embodiment of the present invention.

[0045] In such Figure 7 In the illustrated embodiment, when the intersection is empty, the Y-axis coordinate of the detection point A is determined as the maximum Y-axis coordinate of the prior cutting trajectory. This avoids the situation where the detection point A is not present on the actual surface of the pipe to be cut due to the prior processing of the trajectory, thus preventing detection.

[0046] As a preferred embodiment, S140, determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory may further include: If the bevel trajectory is a post-cut, then proceed to S143: determine the Y-axis coordinate of the detection point as the Y-axis coordinate of the ideal point and decrease it by a second preset distance along the processing direction.

[0047] In this embodiment, the second preset distance can be the dimension of the laser cutting head along the Y-axis direction.

[0048] Please refer to Figure 8 , Figure 8 This is a schematic diagram of the detection point location when the bevel trajectory is cut off after the cut.

[0049] like Figure 8 As shown, when the bevel trajectory is a back cut, the Y-axis coordinate of the detection point A is determined to be the Y-axis coordinate of the ideal point B, and the distance is reduced by a second preset distance along the processing direction to avoid the laser cutting head colliding with the chuck when the bevel trajectory is a back cut.

[0050] In this embodiment, step S400, obtaining the actual Z-axis coordinates when the laser cutting head contacts the detection point, may include: S410: Obtain the actual Z-axis coordinates of the laser cutting head when it sequentially contacts the detection point at several preset sway angles, wherein the preset sway angle is represented as the angle relative to the Z-axis.

[0051] In this embodiment, the preset yaw angles are preferably corresponding to the yaw angles actually required for the cutting bevel trajectory. For example, when the bevel angle is α, the yaw angles are α, 0, and -α. In most actual processing conditions, the bevel angle is 45° (90° hole bevel or 45° oblique cutting), so the preset yaw angles are -45°, 0°, and 45°. Therefore, these three preset yaw angles can be used directly, making the sag measured based on them highly representative and practical. When the preset yaw angle is 0°, the laser cutting head is perpendicular to the surface to be detected.

[0052] In the above embodiments, the present invention uses the method of selecting the detection point in automatic mode as an example to illustrate the method of selecting the detection point position. As an example, the present invention can also select the detection point in manual mode. In manual mode, the method of obtaining the detection point may include: firstly, based on the type of the pipe to be cut, selecting several pipe surfaces as detection surfaces; making the several detection surfaces face upwards in sequence to determine the detection point corresponding to each detection surface; the method of determining the detection point on the current detection surface includes: determining the maximum Y-axis coordinate of the pipe to be cut relative to the chuck as the Y-axis coordinate of the detection point on the current detection surface; determining the X-axis coordinate of the backtracking point with a first predicted distance from the specified edge line as the X-axis coordinate of the detection point. The X-axis coordinates are defined as follows: the specified edge line is the edge line of the surface to be detected that is closest to the ideal point, the edge line of the surface to be detected extends along the Y-axis direction, and the retreat point is a point located in the surface to be detected; or if the type of pipe to be cut is shaped steel, round pipe, or the width of the surface to be detected along the X-axis direction is less than twice the first preset distance, the X-axis coordinates of the midpoint equidistant from the two preset edge lines are determined as the X-axis coordinates of the detection point, the two preset edge lines are characterized as the edge lines of the surface to be detected located on opposite sides of the surface to be detected along the X-axis direction, and the midpoint is a point located in the surface to be detected.

[0053] As an example, in manual mode, the method for obtaining the actual Z-axis coordinates when the laser cutting head contacts the detection point may also include: obtaining the actual Z-axis coordinates when the laser cutting head contacts the detection point sequentially at several preset sway angles, wherein the preset sway angles are represented as angles relative to the Z-axis.

[0054] In this embodiment, the preset yaw angles are preferably corresponding to the yaw angles actually required for the cutting bevel trajectory. For example, when the bevel angle is α, the yaw angles are α, 0, and -α. In most actual processing conditions, the bevel angle is 45° (90° hole bevel or 45° oblique cutting), so the preset yaw angles are -45°, 0°, and 45°. Therefore, these three preset yaw angles can be used directly, making the sag measured based on them highly representative and practical. When the preset yaw angle is 0°, the laser cutting head is perpendicular to the surface to be detected.

[0055] As an example, in manual mode, the method of selecting several pipe surfaces of the pipe to be cut as the detection surfaces in sequence may include: if the pipe to be cut is a square or rectangular pipe, selecting each pipe surface of the square or rectangular pipe as the detection surface in sequence; if the pipe to be cut is a round pipe, selecting the upper and lower pipe surfaces of the round pipe that are symmetrical along the axial direction as the detection surfaces in sequence; if the pipe to be cut is an I-beam, selecting the upper and lower bevels of the I-beam as the detection surfaces in sequence; if the pipe to be cut is an L-beam or a channel steel, selecting each pipe surface of the L-beam or each pipe surface of the channel steel as the detection surfaces in sequence.

[0056] In this embodiment, for square or rectangular tubes, especially rectangular tubes, the width and height are different, resulting in varying rigidity in different directions. Consequently, the effect of gravity on the rectangular tube also differs, directly manifesting as varying sag on each of the four tube surfaces. Therefore, all four tube surfaces of the rectangular tube need to be probed. Since a probe point is selected on each surface, and three preset yaw angles are applied to each point, a total of 12 probes are performed on the square or rectangular tube. Because the entire surface of a circular tube is curved, there is no difference in sag due to different surfaces facing upwards. Therefore, for circular tubes, the axially symmetrical upper and lower tube surfaces are selected sequentially as probes, resulting in 6 probes. For I-beams, only the upper and lower bevels need to be probed to describe the sag of the tube to be cut, resulting in 6 probes. For L-shaped steel or channel steel, the condition of each pipe surface varies considerably, therefore, it is necessary to inspect each pipe surface.

[0057] Accordingly, the present invention also provides a laser cutting device for realizing the method for detecting the sag of the pipe to be cut as described above.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the sagging of a pipe to be cut, characterized in that, include: Based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, the detection point corresponding to the bevel trajectory is determined, and the cutting order of the prior cutting trajectory is prior to the bevel trajectory. Position the surface to be detected upwards and move the laser cutting head above the detection point; The actual Z-axis coordinates when the laser cutting head contacts the detection point are obtained by controlling the capacitive height adjustment device; The sag of the bevel trajectory is obtained based on the absolute value of the difference between the actual Z-axis coordinate and the theoretical Z-axis coordinate of the detection point. The theoretical Z-axis coordinate is the Z-axis coordinate of the detection point when the pipe to be cut is in an ideal state without sag, and the Z-axis is perpendicular to the upward-facing detection surface.

2. The method for detecting the sagging of the pipe to be cut as described in claim 1, characterized in that, Based on the type of pipe to be cut, the prior cutting trajectory, and the bevel trajectory on the surface to be detected, the detection point corresponding to the bevel trajectory is determined, including: Based on the bevel trajectory, obtain all bevel points in the bevel trajectory; Based on the bevel trajectory on the surface to be detected, an ideal point is determined, which is the bevel point that is first cut by the bevel trajectory; Based on the type of pipe to be cut and the ideal point, determine the X-axis coordinate of the detection point; Based on the ideal point, the bevel trajectory, and the prior cutting trajectory, the Y-axis coordinate of the detection point is determined; wherein, the X-axis is perpendicular to the Y-axis and perpendicular to the Z-axis, the Y-axis is perpendicular to the Z-axis, and the Y-axis coordinate increases along the processing direction of the laser cutting head on the pipe to be cut, the processing direction being opposite to the extension direction of the pipe to be cut relative to the chuck.

3. The method for detecting the sagging of the pipe to be cut as described in claim 2, characterized in that, Based on the bevel trajectory on the surface to be detected, the ideal point is determined, including: The type of the bevel trajectory is determined, and the type of the bevel trajectory includes front cut, rear cut, and tube hole; wherein, in the process of cutting the current part to be cut, the front cut is characterized as: the first bevel trajectory cut; the rear cut is characterized as: the last bevel trajectory cut; and the tube hole is characterized as: the bevel trajectory cut after the front cut and before the rear cut. If the type of the bevel trajectory is the front cut, then the ideal point is determined as the bevel point with the smallest Y-axis coordinate in the bevel trajectory; If the type of the bevel trajectory is post-cut or pipe face, then the ideal point is determined as the bevel point with the largest Y-axis coordinate in the bevel trajectory.

4. The method for detecting the sagging of the pipe to be cut as described in claim 2, characterized in that, Based on the type of pipe to be cut and the ideal point, the X-axis coordinate of the detection point is determined, including: The X-axis coordinate of the retreat point with a first predicted distance from the specified edge line is determined as the X-axis coordinate of the detection point. The specified edge line is the edge line of the surface to be detected that is closest to the ideal point. The edge line of the surface to be detected extends along the Y-axis direction. The retreat point is a point located in the surface to be detected.

5. The method for detecting the sagging of the pipe to be cut as described in claim 4, characterized in that, Determining the X-axis coordinate of the detection point based on the type of pipe to be cut and the ideal point further includes: If the type of pipe to be cut is shaped steel, round pipe, or the width of the surface to be detected along the X-axis is less than twice the first preset distance, the X-axis coordinate of the midpoint equidistant from the two preset edge lines is determined as the X-axis coordinate of the detection point. The two preset edge lines are the edge lines of the surface to be detected located on opposite sides of the surface to be detected along the X-axis, and the midpoint is a point located in the surface to be detected.

6. The method for detecting the sagging of the pipe to be cut as described in claim 3, characterized in that, Determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory further includes: Based on the Y-axis machining range and the overall Y-axis machinable range of the bevel trajectory, the intersection of the Y-axis machining range and the overall Y-axis machinable range of the bevel trajectory is obtained. The Y-axis machining range of the bevel trajectory is the Y-axis coordinate range of the bevel trajectory on the surface to be detected, and the overall Y-axis machinable range is the Y-axis coordinate range of the surface to be detected after deleting the Y-axis coordinate range of the previously cut trajectory. Based on the intersection, the Y-axis coordinate of the detection point is determined.

7. The method for detecting the sagging of the pipe to be cut as described in claim 6, characterized in that, Based on the intersection, the Y-axis coordinate of the detection point is determined, including: Determine whether the intersection is empty; If the intersection is empty, then the Y-axis coordinate of the detection point is determined as the maximum Y-axis coordinate of the prior cutting trajectory; If the intersection is not empty, then the Y-axis coordinate of the bevel point in the intersection that has the smallest Y-axis coordinate distance from the ideal point along the Y-axis direction is determined as the Y-axis coordinate of the detection point.

8. The method for detecting the sagging of the pipe to be cut as described in claim 3, characterized in that, Determining the Y-axis coordinate of the detection point based on the ideal point, the bevel trajectory, and the prior cutting trajectory further includes: If the bevel trajectory is a post-cut, then the Y-axis coordinate of the detection point is determined as the Y-axis coordinate of the ideal point, reduced by a second preset distance along the processing direction.

9. The method for detecting the sagging of the pipe to be cut as described in claim 2, characterized in that, Obtaining the actual Z-axis coordinates when the laser cutting head contacts the probe point includes: The actual Z-axis coordinates of the laser cutting head when it sequentially contacts the detection point at several preset sway angles are obtained. The preset sway angle is characterized as the angle relative to the Z-axis.

10. A laser cutting device, characterized in that, This method is used to implement the method for detecting the sagging of the pipe to be cut as described in any one of claims 1 to 9.

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