Method for controlling speed and energy of laser cutting non-circular pipe over corner

Abstract

This invention discloses a method for controlling the speed and energy at corners when laser-cutting non-circular pipes. The post-processor in the CAM system first calculates the distance L1 traveled by the arc segment at the corner in each line of the NC program. The interpolator in the CNC system then calculates the distance L2 traveled by each line of the NC program within the CNC system. Next, the feed rate F1, which needs to be automatically set in the current line of the NC program, is obtained. Finally, the output duty cycle is automatically adjusted based on the feed rate F1 to automatically control the laser output power. By using interpolation to calculate the feed rate that needs to be automatically controlled, and by automatically controlling the laser output energy through the feed rate, the laser automatically adjusts the surface cutting speed at the plane and corners to be consistent during the cutting of non-circular pipes. This improves the processing efficiency at corners, avoids overburning at the corner cut surface, improves the cutting quality of non-circular pipes, and saves time and effort.

Description

Technical Field

[0001] This invention relates to the field of laser cutting technology for square or rectangular tubes, and more particularly to a multi-axis automatic speed control method and an automatic laser energy power control method for the corners of non-circular tubes. Background Technology

[0002] In the field of automated cutting, when using CNC machine tools combined with laser cutting heads to process non-circular tubes such as square or rectangular tubes, for example, when cutting the tube laterally or cutting out non-flat ends of the tube, operators usually use the same speed and power parameters for cutting. If it is cutting the flat part of the tube, there is generally no problem. However, when cutting the non-flat part of the tube at the corner, overheating will often occur at the corner cut surface.

[0003] This is because during the planar path cutting stage, the speed value in the NC program segment is the cutting speed of the planar surface. For a certain type of pipe, users can more easily obtain an empirical value correspondence table between the pipe surface speed and the laser output power. However, during the non-planar path cutting stage, if the speed and power used in the previous planar path cutting stage are continued, overburning will generally occur at the corner cut surface.

[0004] Taking laser cutting of square tubes as an example, let's explain why overburning occurs during the cutting of non-planar paths (i.e., corners). When cutting square tubes, the same speed F value is given in the NC block (i.e., NC program segment) for both the planar path and the corner path. When cutting through a plane, this speed F value is both the resultant speed of all axes and the surface cutting speed of the cutting path. However, when cutting through a corner, this speed F value in the NC block is only the resultant speed of all axes and does not represent the surface cutting speed of the cutting path at the corner. This is because the surface cutting speed of the cutting path corresponding to this resultant speed F value may be much smaller than the actual F value. Therefore, if the laser output power is still used for cutting when cutting through a plane, the surface cutting speed at the corner will be slower, while the laser output power remains constant. As a result, the laser power output received at the corner of the square tube per unit time increases, thus causing the overburning phenomenon.

[0005] To address this issue, in actual processing, operators can only manually adjust the power at the corner to a suitable level based on experience. While this prevents overheating at the corner, it slows down the speed and reduces processing efficiency. Therefore, the current solution is usually to manually adjust the speed and output power at the corner in the NC program based on personal experience before moving from the planar path to the corner path.

[0006] In the NC program segment provided by the CAM system post-processor, each line of the NC block generally only provides the definite position path information for each axis, and the speed information is made available for the operator to set according to actual needs. At the same time, the operator also needs to manually adjust the laser output power according to the type of pipe being cut, the pipe thickness, and the processing speed. The same NC program segment may contain both planar paths and non-planar paths. When adjusting the power for cutting planar paths, the operator needs to adjust the cutting speed and laser output power based on the material and thickness of the pipe and their personal experience in order to achieve a good cutting effect.

[0007] Obviously, to achieve good cutting quality and effect with this solution in the existing technology, a lot of experience testing is required. It often requires a lot of materials and a long time to achieve this. This is because when transitioning from a flat surface to a corner, the operator's manual adjustment is only based on visual perception to adjust the combined speed at the corner. The actual speed of the cutting surface at the corner is completely unknown. It is impossible to use the empirical value correspondence between the cutting surface speed accumulated when cutting the flat surface and the laser output power. This is both time-consuming and laborious, and the final effect will vary from person to person.

[0008] Therefore, the existing laser cutting technology for square or rectangular tubes still needs improvement and development. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a method for controlling the speed and energy at corners when laser-cutting non-circular tubes, which can improve both the processing efficiency at corners and the cutting quality of non-circular tubes.

[0010] The technical solution of this invention is as follows: A method for controlling the speed and energy at corners when laser-cutting non-circular pipes, applied in a CNC numerical control system and CAM system in a Cartesian coordinate system, where X, Y, and Z are linear axes, and the A-axis is a rotational axis that rotates around the X-axis. X, Y, and Z all satisfy the Cartesian coordinate system. If the A-axis does not participate in the motion, the method for controlling the speed and energy at corners employs the following steps:

[0011] In the S110 and CAM systems, the post-processor decomposes the arc segment at the corner into a series of tiny straight line segments as a machining model in each NC program segment at the corner, according to the machining accuracy requirements. The straight-line distance between two coordinate points in the machining model before and after rotation is used as the distance L1 to be traversed in each NC program segment. The following relationship must be satisfied between the two coordinate points:

[0012] Yorig=cosA*Y+sinA*Z formula (4), Zorig=-sinA*Y+cosA*Z formula (5),

[0013] Xorig=X formula (6);

[0014] Where (Xorig, Yorig, Zorig) represent the coordinates of a point in the machining model before rotation, (X, Y, Z) represent the coordinates of a point in the machining model after rotation, and A is the angle of rotation along the A-axis.

[0015] The coordinates of the end point of the arc segment at the corner are taken as the end point of the last line of the NC program segment. The starting point of the last line of the NC program segment is calculated according to the above formula. The starting point of the next line of the NC program segment is the end point of the previous line of the NC program segment. The starting point of the previous line of the NC program segment is calculated according to the above formula until the coordinates of the starting point of the arc segment at the corner are obtained. Then the distance L1 that the arc segment at the corner needs to travel in each line of the NC program segment is obtained.

[0016] If the motion is to be performed at the desired surface shear velocity V, then the execution time of each line of the NC program segment is t1 = L1 / V;

[0017] In the S120 CNC numerical control system, the interpolator treats each axis involved in motion as a linear axis for interpolation. It performs interpolation calculations on each specific small straight line segment path, calculating the distance L2 that each line of the NC program segment moves within the CNC numerical control system:

[0018] L2=sqrt((A(i)-A(i-1))^2+(Y(i)-Y(i-1))^2+(Z(i)-Z(i-1))^2) Formula (2);

[0019] Where i represents the current line of the NC program segment, and i-1 represents the previous line of the NC program segment;

[0020] If the movement is to be performed at the automatically set feed rate, the interpolation time for each line of the NC program segment is t2 = L2 / F1, where F1 is the feed rate that needs to be automatically set in the current line of the NC program segment;

[0021] S130. Under the condition that the execution time is the same, let t1 = t2, then the feed rate F1 automatically set in the current NC program segment is:

[0022] F1 = V * L2 / L1 (Formula 3);

[0023] S140. The laser power is controlled by automatically adjusting the output duty cycle according to the feed rate F1.

[0024] If the feed rate F1 is greater than the set minimum speed but less than the set maximum speed, the duty cycle output will be automatically adjusted in a linear relationship with the feed rate F1.

[0025] The method for controlling the speed and energy at corners during laser cutting of non-circular pipes, wherein in step S140:

[0026] If the feed rate F1 is less than the set minimum rate, maintain the minimum duty cycle output;

[0027] If the feed rate F1 is greater than the set maximum speed, maintain the highest duty cycle output.

[0028] The method for controlling the speed and energy at corners when laser-cutting non-circular pipes, wherein the minimum speed is set to 2 m / min and the maximum speed is set to 10 m / min.

[0029] The method for controlling the speed and energy at corners when laser cutting non-circular pipes, wherein in step S140: a pulse width modulation control mode is adopted, and the output power during cutting is kept at a constant frequency.

[0030] The method for controlling the speed and energy at corners during laser cutting of non-circular pipes further includes the following steps:

[0031] S150. When the thickness of the tube at the corner is different from that at the flat surface, the thickness ratio of the two is used as the power ratio output factor to adjust the laser energy output ratio at the corner.

[0032] A method for controlling the speed and energy at corners during laser cutting of non-circular pipes is applied in CNC and CAM systems using Cartesian coordinates. X, Y, and Z are linear axes, and the A-axis is a rotational axis that rotates around the X-axis. X, Y, and Z all satisfy the Cartesian coordinate system. If the X-axis does not participate in the motion, the speed and energy control method at corners employs the following steps:

[0033] In the S110 and CAM systems, the post-processor calculates the distance L1 that the arc segment at the corner needs to travel in each line of the NC program segment at the corner as follows:

[0034] L1=Dlt_A / 360*2*π*r Formula (1);

[0035] Where r is the radius at the corner of the non-circular pipe, and Dlt_A is the absolute value of the increment of the A-axis rotation; if the desired surface tangential velocity V is to be used for movement, then the execution time of each NC program segment is t1 = L1 / V;

[0036] In the S120 CNC numerical control system, the interpolator treats each axis involved in motion as a linear axis for interpolation. It performs interpolation calculations on each specific small straight line segment path, calculating the distance L2 that each line of the NC program segment moves within the CNC numerical control system:

[0037] L2=sqrt((A(i)-A(i-1))^2+(Y(i)-Y(i-1))^2+(Z(i)-Z(i-1))^2) Formula (2);

[0038] Where i represents the current line of the NC program segment, and i-1 represents the previous line of the NC program segment;

[0039] If the movement is to be performed at the automatically set feed rate, the interpolation time for each line of the NC program segment is t2 = L2 / F1, where F1 is the feed rate that needs to be automatically set in the current line of the NC program segment;

[0040] S130. Under the condition that the execution time is the same, let t1 = t2, then the feed rate F1 that needs to be automatically set in the current NC program segment is:

[0041] F1 = V * L2 / L1 (Formula 3);

[0042] S140. The laser power is controlled by automatically adjusting the output duty cycle according to the feed rate F1; a pulse width modulation control method is adopted to keep the output power at a constant frequency during cutting;

[0043] If the feed rate F1 is greater than the set minimum speed but less than the set maximum speed, the duty cycle output will be automatically adjusted in a linear relationship with the feed rate F1.

[0044] The method for controlling the speed and energy at corners during laser cutting of non-circular pipes, wherein in step S140:

[0045] If the feed rate F1 is less than the set minimum rate, maintain the minimum duty cycle output;

[0046] If the feed rate F1 is greater than the set maximum speed, maintain the highest duty cycle output.

[0047] The method for controlling the speed and energy at corners when laser-cutting non-circular pipes, wherein the minimum speed is set to 2 m / min and the maximum speed is set to 10 m / min.

[0048] The method for controlling the speed and energy at corners when laser-cutting non-circular pipes, wherein the absolute value of the incremental rotation of the A-axis, Dlt_A, in step S110 is equal to 3°.

[0049] The method for controlling the speed and energy at corners during laser cutting of non-circular pipes further includes the following steps:

[0050] S150. When the thickness of the tube at the corner is different from that at the flat surface, the thickness ratio of the two is used as the power ratio output factor to adjust the laser energy output ratio at the corner.

[0051] The present invention provides a method for controlling the speed and energy at corners when laser-cutting non-circular pipes. This method uses interpolation calculations to determine the feed rate that needs to be automatically controlled, and then automatically controls the energy output of the laser by controlling the feed rate. This ensures that the laser cutting speed at the flat surface and at corners is automatically adjusted to be consistent during the cutting process of the non-circular pipe. This improves the processing efficiency at corners, avoids overburning at the corner cut surface, improves the cutting quality of non-circular pipes, and saves time and effort. Attached Figure Description

[0052] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way; the shapes and proportions of the components in the drawings are merely illustrative and are intended to aid in understanding the invention, and are not intended to specifically limit the shapes and proportions of the components of the invention; those skilled in the art, under the guidance of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0053] Figure 1 This is a schematic diagram of the cross-section of a rectangular tube at a corner during laser cutting according to the present invention;

[0054] Figure 2 This is a flowchart of an embodiment of the method for controlling the speed and energy at corners when laser-cutting non-circular pipes according to the present invention;

[0055] Figure 3 This is a graph showing the relationship between the feed rate and the laser output power used in the speed and energy control method for laser cutting of non-circular tubes according to the present invention. Detailed Implementation

[0056] The specific embodiments and examples of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only used to explain the present invention and are not intended to limit the specific embodiments of the present invention.

[0057] The technical principle of this invention, a method for controlling the speed and energy at corners during laser cutting of non-circular pipes, is as follows: the surface cutting speed at corners during pipe cutting is kept consistent with the previously set speed when cutting across a plane. This is because the speed F value given in the NC program segment is the resultant speed of all axes. When cutting across a plane, this speed F value is the surface cutting speed of the planar path, and operators typically have an experience table showing a one-to-one correspondence between speed and power. However, when cutting at corners, the speed F value in the NC program segment is the resultant speed of all axes, not the surface cutting speed at the corner. Nevertheless, the operator expects to calculate this speed F value and set the power according to the experience table of speed and power when cutting across a plane.

[0058] Therefore, the difficulty of the technical solution of this invention lies in calculating the required feed rate F1 in the NC program based on the principle that the speed when passing through the plane is equal to the cutting speed of the pipe surface at the corner. Then, before the CNC system performs interpolation, the original speed F value at the corner is modified to the calculated feed rate F1. This allows the surface cutting speed when passing through the plane to be automatically adjusted to be consistent with that when passing through the corner, thereby ensuring the cutting speed when passing through the corner and thus improving the processing efficiency.

[0059] The following section will explain in two parts how to automatically change speed and power when laser cutting non-circular pipes passes through corners.

[0060] I. Automatic transmission process

[0061] like Figure 1 As shown, taking a rectangular tube with a rectangular cross-section cut by laser as an example, the corner refers to... Figure 1 The four arc corners, the external dimensions of the rectangular tube cross-section (length L, width W), the radius r at the corner, the rotation angles A, B, and C, the slope K, the coordinate axes Y and Z, and the X-axis (the axial direction of the rectangular tube) are all considered. Before cutting, the rectangular tube is horizontally clamped and fixed on a four-jaw chuck on the horizontal axis (X-axis). The rectangular tube can be cut by rotating the laser head on the vertical axis (A-axis) around the horizontal axis of the four-jaw chuck. In this case, the linear axis X-axis is considered not to participate in the movement. Alternatively, the rectangular tube can be cut by rotating the four-jaw chuck around the horizontal axis (the center point of the rectangular tube cross-section) without rotating the laser head on the vertical axis. In this case, the rotation axis A-axis is considered not to participate in the movement.

[0062] As mentioned earlier, the key is to calculate the feed rate F1 in the NC program segment at the corner, and to convert this feed rate F1 into a surface cutting speed at the corner that corresponds to the feed rate when crossing the plane. Figure 2 As shown.

[0063] Considering a slightly simpler multi-axis case, in which the axis perpendicular to the direction of rotation does not participate in the motion, such as the X-axis in the NC program segment below, the theoretical value of the feed rate F1 when passing through a corner can be calculated using the following method.

[0064] First, here is a portion of the NC code for the corner crossing:

[0065] N1056 G01 X10.000 Y0.000 A-90.000Z11.000 F=P70

[0066] N1058 G01 X10.000 Y9.000 A-90.000Z11.000

[0067] N1062 G01 X10.000 Y8.512 A-87.000Z11.459

[0068] N1064 G01 X10.000 Y8.003 A-84.000Z11.891

[0069] N1066 G01 X10.000 Y7.473 A-81.000Z12.297

[0070] N1068 G01 X10.000 Y6.924A-78.000Z12.675

[0071] N1070 G01 X10.000 Y6.358 A-75.000Z13.023

[0072] N1072 G01 X10.000 Y5.774A-72.000Z13.341

[0073] N1074 G01 X10.000 Y5.175 A-69.000Z13.628

[0074] N1076 G01 X10.000 Y4.563 A-66.000Z13.883

[0075] N1078 G01 X10.000 Y3.937A-63.000Z14.105

[0076] N1080 G01 X10.000 Y3.301 A-60.000Z14.294

[0077] N1082 G01 X10.000 Y2.654 A-57.000Z14.450

[0078] N1084 G01 X10.000 Y1.999 A-54.000Z14.571

[0079] N1086 G01 X10.000 Y1.337 A-51.000Z14.658

[0080] N1088 G01 X10.000 Y0.670 A-48.000Z14.710

[0081] N1090 G01 X10.000 Y0.000 A-45.000Z14.728

[0082] N1092 G01 X10.000 Y-0.670A-42.000Z14.710

[0083] N1094 G01 X10.000 Y-1.337A-39.000Z14.658

[0084] N1096 G01 X10.000 Y-1.999A-36.000Z14.571

[0085] N1098 G01 X10.000 Y-2.654A-33.000Z14.450

[0086] N1100 G01 X10.000 Y-3.301A-30.000Z14.294

[0087] N1102 G01 X10.000 Y-3.937A-27.000Z14.105

[0088] N1104 G01 X10.000 Y-4.563A-24.000Z13.883

[0089] N1106 G01 X10.000 Y-5.175A-21.000Z13.628

[0090] N1108 G01 X10.000 Y-5.774A-18.000Z13.341

[0091] N1110 G01 X10.000 Y-6.358A-15.000Z13.023

[0092] N1112 G01 X10.000 Y-6.924A-12.000Z12.675

[0093] N1114 G01 X10.000 Y-7.473A-9.000Z12.297

[0094] N1116 G01 X10.000 Y-8.003A-6.000Z11.891

[0095] N1118 G01 X10.000 Y-8.512A-3.000Z11.459

[0096] N1120 G01 X10.000 Y-9.000A0.000 Z11.000.

[0097] In the NC program segment above, the X-axis, Y-axis, and Z-axis are all linear axes, and the A-axis is a rotation axis that rotates around the X-axis. The X-axis, Y-axis, and Z-axis all satisfy the Cartesian coordinate system. From the multi-axis positions in the NC program segment above, we can know that the N1058 NC program segment is the process of passing through the plane along the Y direction, and the N1062 to N1120 NC program segments are the process of rotating 90 degrees through the corner. In the N1056 NC program segment, F = P70 is the cutting speed set when passing through the plane, and P70 is the variable name that stores the speed parameter value.

[0098] Secondly, in the field of automated laser cutting, the post-processor in the CAM system first decomposes this non-planar path (such as the corner of a square tube) into a series of tiny straight line segments as a processing model according to the processing accuracy requirements. Then, the interpolator in the CNC system performs interpolation calculations on each specific tiny straight line segment.

[0099] In the CAM system, the post-processor sets the absolute value of the A-axis rotation increment to Dlt_A in each NC program segment at the corner. For example, in the NC program segment above, Dlt_A is set to 3 degrees. When the X-axis does not participate in the movement, the distance L1 that the arc segment at the corner needs to travel in each NC program segment can be calculated according to formula (1):

[0100] L1=Dlt_A / 360*2*π*r Formula (1);

[0101] Where r is the radius at the corner of the square tube, if the desired surface shear velocity V is to be used for movement, then the execution time t1 of each NC program segment is L1 / V, and the feed rate to be set in the NC program segment is F1. The interpolator in the CNC system interpolates each NC program segment by treating each axis involved in the movement as a linear axis. Therefore, the distance L2 of each NC program segment moving in the CNC system can be calculated according to formula (2):

[0102] L2=sqrt((A(i)-A(i-1))^2+(Y(i)-Y(i-1))^2+(Z(i)-Z(i-1))^2) Formula (2);

[0103] Where i is the current line of the NC program segment, i-1 is the previous line of the NC program segment, and the interpolation time for each line of the NC program segment is t2 = L2 / F1; therefore, the above two must meet the requirement that the execution time is equal, that is, L1 / V = L2 / F1, and the calculation formula (3) for the feed rate F1 that can be automatically set in the current line of the NC program segment is obtained:

[0104] F1 = V * L2 / L1 (Formula 3);

[0105] The above calculation formula (3) is a relatively simple calculation method. In this case, the X-axis does not participate in the motion. If the X-axis participates in the motion, the motion trajectory of each NC program segment when passing the corner will become very complicated, making the L1 calculation formula in the above formula (1) no longer applicable. Therefore, in this invention, another method using a rotation matrix is ​​proposed to calculate the motion trajectory distance L1 when passing the corner.

[0106] The following describes how to cleverly solve this problem using a rotation matrix. Due to the involvement of multiple axes, including linear axes and rotation axes, it becomes very difficult to calculate the actual motion trajectory distance L1 of each line of NC program segment. Therefore, if the rotation axis A is not involved in the motion of any axis in each line of NC program segment, then the remaining axes involved in the motion of each line of NC program segment are linear axes. In this way, the motion trajectory distance L1 of each line of NC program segment can be easily calculated, which is the straight line segment composed of all linear axes. Therefore, if the influence of the rotation axis A on the motion trajectory in each line of NC program segment can be eliminated, the actual motion trajectory distance L1 of each line of NC program segment can be calculated.

[0107] So how do we eliminate the influence of rotation axis A on the motion trajectory in the NC program segment? We can refer to the following rotation matrix method: If vector P1 is rotated by an angle α in a coordinate system to obtain vector P2, then P2 = R(α) * P1, where R(α) is the rotation matrix.

[0108] In fact, the coordinate values ​​of each axis in each line of the NC program segment are the new coordinate values ​​generated by the original coordinate points in the machining model after rotating by a fixed angle. Since each line of the NC program segment is a tiny line segment, the actual trajectory distance L1 traversed by each line of the NC program segment is approximately equal to the straight-line distance between two coordinate points in the machining model. As long as the NC program segment gives the coordinate values ​​of the points in the machining model after rotation, the coordinate values ​​of the points in the machining model before rotation can be obtained by multiplying by the inverse of the rotation matrix. The coordinate values ​​of the points before rotation can be calculated according to formulas (3), (4) and (5):

[0109] Yorig=cosA*Y+sinA*Z formula (4), Zorig=-sinA*Y+cosA*Z formula (5),

[0110] Xorig=X formula (6);

[0111] Where A is the angle of rotation along the A-axis, X, Y and Z are the coordinates of the points in the machining model after rotation in the NC program segment, and Xorig, Yorig and Zorig are the coordinates of the points in the machining model before rotation.

[0112] The coordinates of the end point of the arc segment at the corner are taken as the end point of the last line of the NC program segment. The starting point of the last line of the NC program segment is calculated according to the above formula. The starting point of the next line of the NC program segment is the end point of the previous line of the NC program segment. The starting point of the previous line of the NC program segment is calculated according to the above formula until the coordinates of the starting point of the arc segment at the corner are obtained. Then the distance L1 that the arc segment at the corner needs to travel in each line of the NC program segment is obtained. Then, the feed rate F1 that needs to be set in the NC program segment can be solved by the calculation in the above formulas (2) and (3).

[0113] I. Automatic power conversion process

[0114] The first part can be used to calculate the feed rate F1 when the automatic speed change occurs at the corner. At this time, the surface shear velocity at the corner is consistent with the surface shear velocity when the plane is crossed. Therefore, if the duty cycle output when crossing the corner can be kept consistent with the duty cycle output ratio when cutting the plane in the second part, a more ideal cutting effect will be obtained.

[0115] In laser output power control, PWM (Pulse Width Modulation) control is mostly used to maintain a constant frequency of output power during cutting. The laser power is controlled by adjusting the output duty cycle based on the feed rate F1. This control mode is also known as V3 mode. This mode can be selected in the NC program segment via the programming word address V3. The frequency of the output power is specified via the word address T. The NC program segment format is shown in line N10 below, where G110 represents the preparatory function before activating laser power output, used to set the mode selection, axis plane selection, and control mode mentioned above. The selection; G111 in line N20 is used to set the duty cycle output corresponding to the minimum speed; G112 in line N30 is used to set the duty cycle output corresponding to the maximum speed; when the feed rate F1 is less than the set minimum speed by 2 m / min, the minimum duty cycle output is maintained; when the feed rate F1 is greater than the set maximum speed by 10 m / min, the maximum duty cycle output is maintained; when the feed rate F1 is greater than the set minimum speed by 2 m / min and less than the set maximum speed by 10 m / min, the duty cycle output is automatically controlled according to a linear relationship with the feed rate F1, such as... Figure 3 As shown.

[0116] The following is a portion of the NC program code:

[0117] N10 G110 X1 Y1 V3 T5000 (Programming Mode 3, Pulse Frequency 5kHz)

[0118] N20 G111 V18 F2000 (Lower limit duty cycle 18%, feed rate 2m / min)

[0119] N30 G112 V60 F10000 (Upper limit duty cycle 60%, feed rate 10m / min).

[0120] It should be noted that, Figure 3 The graph showing the relationship between feed rate and laser output power is also applicable to the speed and energy control method when laser cutting non-circular tubes in a plane.

[0121] In addition, a power ratio output factor can be set. When the thickness of the tube at the corner is different from that at the flat surface, the ratio of this tube thickness can be used as the power ratio output factor to change the power ratio output, which can make the laser cutting effect better.

[0122] The speed and energy control method for laser cutting non-circular pipes at corners proposed in this invention effectively solves the problem of automatic speed and power variation for multi-axis cutting at corners. Operators no longer need to spend a lot of time testing the appropriate speed and power settings at corners. They only need to set the cutting speed and laser output power according to the experience table provided with the CNC machine tool when cutting a plane. The CNC machine tool will then automatically adjust the speed and power for cutting at corners based on the set speed and power settings, saving both time and effort and improving the cutting quality of non-circular pipes.

[0123] It should be noted that the speed and energy control method for laser cutting non-circular pipes at corners in this invention significantly improves the cutting quality of the pipes after use. It does not achieve simple functions with complex structures, nor does it use conventional or simple features for combination or stacking. Therefore, it conforms to the common sense of technical improvement and has practicality.

[0124] Any content not described in detail in this specification is prior art known to those skilled in the art.

[0125] It should be understood that the above description is only a preferred embodiment of the present invention and is not sufficient to limit the technical solution of the present invention. For those skilled in the art, within the spirit and principles of the present invention, additions, subtractions, substitutions, transformations or improvements can be made based on the above description, and all such additions, subtractions, substitutions or improvements should fall within the protection scope of the appended claims of the present invention.

Claims

1. A speed and energy control method for laser cutting a non-circular pipe over a corner, applied in a CNC system and a CAM system in a Cartesian coordinate system, X, Y and Z are linear axes, and A is a rotating axis, A rotates around the X axis, X, Y and Z all satisfy the Cartesian coordinate system; characterized in that, if A does not participate in the movement, the speed and energy control method over the corner adopts the following steps: S110, the postprocessor in the CAM system decomposes the corner arc segment into a series of micro straight line segment paths as a processing model according to the processing precision requirement in each NC program segment over the corner, and calculates the straight line distance between the two coordinate points before and after rotation of the point in the processing model as the distance L1 to be walked in each NC program segment, and the two coordinate points satisfy the following relations simultaneously: Yorig=cosA*Y+sinA*Z Formula (4), Zorig=-sinA*Y+cosA*Z Formula (5), Xorig=X Formula (6); wherein (Xorig, Yorig, Zorig) represents the coordinate value of the point in the processing model before rotation, (X, Y, Z) represents the coordinate value of the point in the processing model after rotation, and A is the angle of rotation of A; the coordinate value of the end point of the corner arc segment is taken as the end point of the last NC program segment in the NC program segment, the start point of the last NC program segment is calculated according to the above relations, the start point of the previous NC program segment is calculated according to the above relations, and the coordinate value of the start point of the corner arc segment is obtained, and then the distance L1 to be walked in each NC program segment is obtained; if the desired surface cutting speed V is to be moved, the execution time t1 of each NC program segment is L1 / V; S120, the interpolator in the CNC system interpolates each participating axis as a linear axis, performs interpolation operation on each specific micro straight line segment path, and calculates the distance L2 moved in the CNC system for each NC program segment as: L2=sqrt((A(i)-A(i-1))^2+(Y(i)-Y(i-1))^2+(Z(i)-Z(i-1))^2) Formula (2); wherein i is the current NC program segment, and i-1 is the previous NC program segment; if the automatically set feed combined speed is to be moved, the time t2 of executing interpolation of each NC program segment is L2 / F1, wherein F1 is the automatically set feed combined speed required in the current NC program segment; S130, under the condition that the execution time is the same, t1=t2, the automatically set feed combined speed F1 in the current NC program segment is obtained as: F1=V*L2 / L1 Formula (3); S140, the laser power is controlled in the mode of automatically adjusting the output duty cycle according to the feed combined speed F1, the pulse width modulation control mode is adopted, and the output power during cutting is kept at a constant frequency. ​ If the combined feed speed F1 is greater than the set minimum speed and less than the set maximum speed, the duty cycle output is automatically adjusted in linear relation to the combined feed speed F1; S150, when the pipe thickness at the corner is different from the pipe thickness at the plane, the thickness ratio of the two is taken as the power ratio output example factor, which is used to adjust the laser energy output ratio at the corner.

2. The method of controlling the speed and energy of a laser cutting non-circular tube over a corner according to claim 1, wherein, In the step S140: If the combined feed speed F1 is less than the set minimum speed, the minimum duty cycle output is maintained; If the combined feed speed F1 is greater than the set maximum speed, the maximum duty cycle output is maintained.

3. The method of controlling the speed and energy of a laser cutting non-circular tube over a corner according to claim 2, wherein: The set minimum speed is 2 m / min, and the maximum speed is 10 m / min.

4. A speed and energy control method for laser cutting of a non-circular pipe at a corner, applied in a CNC numerical control system and a CAM system in a Cartesian coordinate system, X, Y and Z are linear axes, and A is a rotary axis, A rotates around the X axis, and X, Y and Z satisfy the Cartesian coordinate system; characterized in that, If the X axis does not participate in the movement, the speed and energy control method at the corner adopts the following steps: S110, the postprocessor in the CAM system calculates the distance L1 that the arc segment at the corner needs to pass in each NC program segment at the corner as: L1=Dlt_A / 360*2*π*r formula (1); Wherein, r is the radius of the non-circular pipe at the corner, and Dlt_A is the incremental absolute value of A axis rotation; if the desired surface cutting speed V is to be moved, the execution time t1 of each NC program segment is L1 / V; S120, the interpolator in the CNC numerical control system interpolates each axis participating in the movement as a linear axis, and calculates the distance L2 that each NC program segment moves in the CNC numerical control system as: L2=sqrt((A(i)-A(i-1))^2+(Y(i)-Y(i-1))^2+(Z(i)-Z(i-1))^2) formula (2); Wherein, i is the current NC program segment, and i-1 is the last NC program segment; If the desired surface cutting speed V is to be moved, the execution time t1 of each NC program segment is L1 / V; S130, under the condition that the execution time is the same, let t1=t2, then the combined feed speed F1 that needs to be automatically set in the current NC program segment is: F1=V*L2 / L1 formula (3); S140, the laser power is controlled by automatically adjusting the output duty cycle according to the feed speed F1; the pulse width modulation control mode is adopted, and the output power during cutting is kept constant frequency; If the combined feed speed F1 is greater than the set minimum speed and less than the set maximum speed, the duty cycle output is automatically adjusted in linear relation to the combined feed speed F1; S150, when the pipe thickness at the corner is different from the pipe thickness at the plane, the thickness ratio of the two is taken as a power proportion output factor for adjusting the laser energy output proportion at the corner.

5. The method of controlling the speed and energy of a laser cutting non-circular tube over a corner according to claim 4, wherein, In the step S140: If the feeding combined speed F1 is less than the set minimum speed, the minimum duty cycle output is maintained; If the feeding combined speed F1 is greater than the set maximum speed, the maximum duty cycle output is maintained.

6. The method of controlling the speed and energy of a laser cutting non-circular tube over a corner according to claim 5, wherein: The set minimum speed is 2 m / min, and the maximum speed is 10 m / min.

7. The method of controlling the speed and energy of a laser cutting non-circular tube over a corner according to claim 4, wherein: In the step S110, the incremental absolute value Dlt_A of the A-axis rotation is equal to 3°.

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