CN118513678A - Synchronous output method for equidistant laser pulse positions of three-dimensional curved surface - Google Patents
Synchronous output method for equidistant laser pulse positions of three-dimensional curved surface Download PDFInfo
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Abstract
The invention discloses a synchronous output method for equidistant laser pulse positions of a three-dimensional curved surface, which relates to the technical field of laser cutting of five-axis machine tools, and comprises the following steps: constructing a space motion model of the laser focus under a workpiece coordinate system; in each function call period, the current displacement of each axis of the five-axis machine tool is obtained through an encoder; calculating the current coordinate of the laser focus under the workpiece coordinate system according to the axial position feedback obtained by the encoder, and comparing the current coordinate with the calculated last coordinate position to obtain the vector distance of the laser focus advancing under the workpiece coordinate system in the period; obtaining the current processing total length of the laser on the three-dimensional curved surface through small line segment fitting; and in each function call period, comparing and outputting according to the calculated total length of the laser processing. The invention ensures the light spot uniformity when the laser cuts the brittle material on the basis of not increasing the cost, ensures that the light spot overlapping rate is not influenced by the laser scanning speed, and improves the processing quality and efficiency.
Description
Technical Field
The invention relates to the field of five-axis machine tool laser cutting, in particular to a synchronous output method for three-dimensional curved surface equidistant laser pulse positions.
Background
Laser processing has advantages of no contact, high instantaneous power, and the like, and is thus increasingly applied to the field of cutting of brittle materials. When the crack control method is used for cutting the brittle material, stable laser energy input is required to be ensured on a cutting track, and the consistent light spot overlapping ratio on the cutting path can improve the uniformity of laser energy distribution, thereby improving the cutting quality.
In the prior art, a stable light spot overlapping ratio is generally ensured by controlling a scanning speed or a repetition frequency, and the specific mode is that the scanning speed of laser on a cutting path is kept unchanged when the repetition frequency of the laser is fixed according to a light spot interval s, wherein the light spot interval s depends on the repetition frequency f and the scanning speed v of the laser, namely s=v/f; or a variable frequency laser is used, and the output frequency of the laser is changed when the scanning speed is changed. However, if the scanning speed is kept unchanged, the upper limit of the scanning speed is greatly limited by the speed constraint of the machine tool rotating shaft and the linear shaft in the actual machining process, especially when complex space curved surfaces are cut, so that the machining efficiency is reduced; if an adjustable frequency laser is used, the cost is increased, and the output power of the laser is changed, which affects the processing technology.
Disclosure of Invention
Aiming at the technical problems of low processing efficiency and increased processing cost in the scheme for guaranteeing the uniformity of light spots in the prior art, the invention provides the synchronous output method for the equidistant laser pulse positions of the three-dimensional curved surface, which can ensure that the overlapping ratio of the light spots is not influenced by the scanning speed during laser cutting on the basis of not increasing the cost, thereby improving the quality and the efficiency of laser pulse processing.
In order to solve the above problems, the present invention provides a method for synchronously outputting the positions of laser pulses at equal intervals on a three-dimensional curved surface, the method comprising the steps of:
S 100: constructing a motion model of the laser focus under a workpiece coordinate system;
S 200: in each function call period, the current displacement of each axis of the five-axis machine tool is obtained through an encoder;
s 300: calculating the moving distance of the laser focus under the coordinate system of the workpiece in the current function period;
S 400: obtaining the current total processing distance of the laser on the three-dimensional curved surface through small line segment fitting;
S 500: and in each function calling period, comparing and outputting according to the calculated total distance of laser processing.
Further, in step S 100, the constructing a motion model of the laser focus under the workpiece coordinate system specifically includes:
Step S 110: defining a laser sub-chain, and deducing the coordinate position of a laser focus under a machine tool coordinate system;
Step S 120: defining a workpiece sub-chain, and calculating a conversion matrix from a laser coordinate system to a workpiece coordinate system;
step S 130: and obtaining a motion model of the laser focus under the coordinate system of the workpiece.
Further, in step S 110, the defining the laser sub-chain and deriving the coordinate position of the laser focal point in the machine coordinate system specifically includes the steps of:
Step S 111: the laser sub-chain consists of a linear axis Z and a laser, and the laser is fixed on the linear axis Z;
Step S 112: respectively placing a coordinate system X 3Y3Z3 and X 4Y4Z4 at a fixed point and a laser focus position of the laser, wherein the XYZ axis directions of the coordinate system are consistent with the three-axis directions of a machine tool coordinate system, and rotation transformation does not occur;
step S 113: the calculation expression for determining the coordinate position of the laser focus in the machine tool coordinate system is as follows:
Wherein: (d x,dy,-dz) represents the relative offset of the origin of the coordinate system X 3Y3Z3 and the origin of the machine coordinate system in the direction of X, Y, Z axis, respectively, and P z represents the encoder feedback displacement of the linear axis Z; l Laser represents the vector distance of the fixed point of the laser to the laser focus, and the vector direction of L Laser is parallel to the Z-axis direction of the machine coordinate system.
Further, in step S 120, the defining the workpiece sub-chain and calculating the transformation matrix from the laser coordinate system to the workpiece coordinate system specifically includes:
Step S 121: the workpiece sub-chain consists of a linear axis Y, a linear axis X, a rotating shaft B, a rotating shaft C and workpieces placed on the upper surface of the rotating shaft C in sequence;
Step S 122: establishing a base coordinate system X 0Y0Z0 on the turntable, representing the translational motion of the X, Y axis by the motion of the base coordinate system, wherein the base coordinate system does not perform rotation transformation;
Step S 123: the coordinate system X 1Y1Z1,Z1 is fixedly connected with the rotating shaft B, the axis of the coordinate system X 1Y1Z1,Z1 coincides with the axis of the rotating shaft B, and the origin of the coordinate system X 1Y1Z1 is positioned at the intersection point of the axis of the B, C shaft;
The coordinate system X 2Y2Z2,Z2 is fixedly connected with the rotating shaft C, the axis of the coordinate system X 2Y2Z2 is coincident with the axis of the rotating shaft C, and the origin of the coordinate system X 2Y2Z2,Z2 is positioned at the center of the upper surface of the turntable;
Step S 124: the workpiece coordinate system w is completely coincident with the coordinate system X 2Y2Z2, and the workpiece coordinate system w is transformed along with the transformation of the coordinate system X 2Y2Z2;
Step S 125: and determining a transformation matrix formula of the position relation of the adjacent connecting rods according to robot kinematics.
Further, in step S 125, the transformation matrix formula R i of the adjacent link positional relationship is:
Wherein α i-1 represents a deflection angle from Z i-1 to Z i with respect to the direction of X i-1, a i-1 represents a displacement from Z i-1 to Z i in the direction of X i-1, θ i represents a deflection angle from X i-1 to X i with respect to the direction of Z i, d i represents a displacement from X i-1 to X i in the direction of Z i, θ B represents an encoder feedback displacement of the rotation axis B, θ C represents an encoder feedback displacement of the rotation axis C, and d represents a distance between an intersection point of the rotation axis B with the axis of the rotation axis C and an origin of the workpiece coordinate system.
Further, in step S 120, according to the laser sub-chain, the transformation matrix T Stock from the machine coordinate system to the workpiece coordinate system is:
TStock＝R0×R1×R2
Wherein: r 0 represents a transformation matrix from a machine tool coordinate system to a base coordinate system; r 1 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2; r 2 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2.
Further, in step S 130, the obtained motion model of the laser focus under the workpiece coordinate system is:
Wherein Q' Laser is the coordinate position of the laser focus under the workpiece coordinate system.
Further, in step S 300, the calculating the moving distance of the laser focus in the current function period under the workpiece coordinate system specifically includes:
Step S 310: comparing the position Q 'Laser(x1,y1,z1) of the laser focus in the workpiece coordinate system at the current time with the position Q' 0(x0,y0,z0 of the laser focus in the workpiece coordinate system at the previous time;
Step S 320: the vector distance of the laser focus travelling in the current function period is calculated as follows:
Wherein: x 1 represents the x-axis coordinate of the laser focus at the current time in the workpiece coordinate system, y 1 represents the y-axis coordinate of the laser focus at the current time in the workpiece coordinate system, and z 1 represents the z-axis coordinate of the laser focus at the current time in the workpiece coordinate system; x 0 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, y 0 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, and z 0 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the previous time.
Further, in step S 400, the obtaining, by small line segment fitting, the current total distance of the laser on the three-dimensional curved surface specifically includes:
step S 410: calling a laser pulse output function in a motion controller, wherein the calling period is 1ms;
step S 420: and summing the processing vector distances obtained in each function call period to obtain the current total processing distance.
Further, in step S 500, in each function call period, the comparing output according to the calculated total distance of the laser processing specifically includes:
step S 510: judging whether the calculated total distance of laser processing is an integer multiple of a set interval value or not in each function calling period;
Step S 520: if the total laser processing distance is integral multiple of the set interval value, starting a timer, outputting a high level by a motion controller, enabling the laser to output pulses, and closing the timer after a period of time;
Step S 530: if the total distance of the laser processing is not integral multiple of the set interval value, the motion controller outputs a low level so as to stop the output of the laser.
Compared with the prior art, the invention has the following beneficial effects:
1. The application relates to a synchronous output method of a three-dimensional curved surface equidistant laser pulse position, which comprises the steps of constructing a space motion model of a laser focus under a workpiece coordinate system; in each function call period, the current displacement of each axis of the five-axis machine tool is obtained through an encoder; calculating the current coordinate of the laser focus under the workpiece coordinate system according to the axial position feedback obtained by the encoder, and comparing the current coordinate with the calculated last coordinate position to obtain the vector distance of the laser focus advancing under the workpiece coordinate system in the period; obtaining the current processing total length of the laser on the three-dimensional curved surface through small line segment fitting; and in each function call period, comparing and outputting according to the calculated total length of the laser processing. And calculating the current total machining distance of the focus of the laser according to the axial displacement parameter fed back by the encoder, so as to control the switching light of the laser, and therefore, the output position of the laser pulse is not influenced by the scanning speed. When complex tracks are processed, under the condition that the light spot intervals are consistent, the scanning speed can be changed according to the conditions of each track segment, so that the laser processing efficiency is greatly improved; during actual processing, some unavoidable acceleration and deceleration conditions, such as acceleration and deceleration at the beginning and ending sections of the track, will not change the light spot overlapping ratio on the cutting track, thereby improving the processing quality.
2. Can ensure the uniformity of light spots acting on the surface of the material when the laser cuts the brittle material on the basis of not increasing the cost, the light spot overlapping rate on the track is not influenced by the laser scanning speed, and the processing quality and efficiency are improved.
Drawings
FIG. 1 is a schematic flow chart of a method for synchronously outputting the positions of laser pulses at equal intervals on a three-dimensional curved surface in an embodiment of the invention;
FIG. 2 is a detailed flowchart of step S 100 in an embodiment of the present invention;
FIG. 3 is a detailed flowchart of step S 120 in an embodiment of the present invention;
FIG. 4 is a schematic diagram of a dual turret five-axis machine tool according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a control mechanism of a laser pulse output system according to an embodiment of the present invention;
FIG. 6 is a diagram of two open-chain structures of a machine tool according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a coordinate system position on a sub-chain of a workpiece in an embodiment of the invention;
FIG. 8 is a schematic diagram of a coordinate system position on a laser sub-chain in an embodiment of the present invention;
fig. 9 is a schematic diagram of laser program operation control of a dual turret five-axis machine tool according to an embodiment of the present invention.
Reference numerals illustrate:
1-a straight axis Z; 2-laser focus; 3-a linear axis Y; 4-a straight line axis X; 5-a rotation axis B; 6-a rotation axis C; 7-a workpiece; an 8-X axis encoder; a 9-Y axis encoder; a 10-Z axis encoder; an 11-B axis encoder; a 12-C axis encoder; 13-a motion controller; 14-an industrial personal computer; 15-laser.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; the two components can be directly connected or indirectly connected through an intermediate medium, or can be communicated inside the two components, or can be connected wirelessly or in a wired way. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In the prior art, laser processing is widely applied to the field of cutting brittle materials, and in the use process, a stable light spot overlapping ratio is generally ensured by controlling the laser scanning speed or the repetition frequency, namely, a light spot interval s depends on the repetition frequency f and the scanning speed v of the laser 15, namely, s=v/f, and when the repetition frequency of the laser 15 is fixed, the scanning speed of the laser on a cutting path is kept unchanged; or a variable frequency laser 15 may be used to simultaneously vary the laser output frequency as the scan speed is varied.
However, if the scanning speed of the laser 15 is kept unchanged, the upper limit of the scanning speed is greatly limited by the speed constraint of the machine tool rotating shaft and the linear shaft in the actual machining process, especially when complex space curved surfaces are cut, so that the machining efficiency is reduced; if an adjustable frequency laser is used, the cost is increased, and the output power of the laser is changed, which affects the processing technology.
In order to solve the above technical problems, referring to fig. 1 to 9, an embodiment of the present invention provides a method for synchronously outputting laser pulse positions with equal intervals on a three-dimensional curved surface, where the method includes the steps of:
S 100: constructing a motion model of the laser focus under a workpiece coordinate system;
In this step, when constructing a spatial motion model of the laser focus in the workpiece coordinate system, the present embodiment adopts the machine tool coordinate system as an intermediate quantity and proceeds in three steps.
S 200: in each function call period, the current displacement of each axis of the five-axis machine tool is obtained through an encoder;
in the step, the current displacement of each axis obtained by the encoder is substituted into the motion model, so that the coordinate position of the laser focus under the workpiece coordinate system can be obtained during each function call period.
S 300: calculating the moving distance of the laser focus under the coordinate system of the workpiece in the current function period;
S 400: obtaining the current total processing distance of the laser 15 on the three-dimensional curved surface through small line segment fitting;
S 500: and in each function calling period, comparing and outputting according to the calculated total distance of laser processing.
According to the embodiment of the invention, the current processing total distance of the laser focus 2 is calculated according to the axial displacement parameter fed back by the encoder, so that the switch of the laser 15 is controlled, and therefore, the output position of the laser pulse is not influenced by the scanning speed.
When complex tracks are processed, under the condition that the light spot intervals are consistent, the scanning speed can be changed according to the conditions of each track segment, so that the laser processing efficiency is greatly improved; during actual processing, some unavoidable acceleration and deceleration conditions, such as acceleration and deceleration at the beginning and ending sections of the track, will not change the light spot overlapping ratio on the cutting track, thereby improving the processing quality.
Specifically, referring to fig. 2, in step S 100 of the present invention, the construction of the motion model of the laser focus under the workpiece coordinate system specifically includes:
step S 110: defining a laser sub-chain and deducing the coordinate position of the laser focus under the coordinate system of the machine tool.
Step S 120: defining a workpiece sub-chain, and calculating a conversion matrix from a laser coordinate system to a workpiece coordinate system.
Step S 130: and obtaining a motion model of the laser focus under the coordinate system of the workpiece.
From a kinematic point of view, there is an open chain structure similar to a robotic arm, from the machine coordinate system to the laser focus, and from the machine coordinate system to the workpiece coordinate system, known as a laser sub-chain and a workpiece sub-chain, respectively.
The axes are regarded as connecting rods and joint structures of the mechanical arm, a coordinate system is fixedly connected for each movement axis of the machine tool according to the D-H convention, and the movement model of the laser focus under the coordinate system of the workpiece can be obtained by respectively deducing two sub-chains (a laser sub-chain and a workpiece sub-chain) through translation and rotation transformation of the coordinate system.
Specifically, referring to fig. 3, in step S 110 of the present invention, the defining the laser sub-chain and deriving the coordinate position of the laser focus in the machine coordinate system specifically includes the steps of:
Step S 111: the laser sub-chain consists of a linear axis Z1 and a laser 15, and the laser 15 is fixed on the linear axis Z1.
Step S 112: coordinate systems X 3Y3Z3 and X 4Y4Z4 are respectively placed at the fixed point and the laser focus position of the laser 15, and the XYZ axis directions of the coordinate systems are consistent with the three-axis directions of the machine tool coordinate system, and rotation transformation does not occur.
The derivation process of the laser subchain is as follows:
the laser sub-chain consists of a linear axis Z1 and a laser 15, and the laser 15 is fixed on the linear axis Z1.
Placing coordinate systems X 3Y3Z3 and X 4Y4Z4 at a fixed point and a laser focus position of the laser 15 respectively, wherein the XYZ axis directions of the coordinate systems are consistent with the three-axis directions of a machine tool coordinate system and do not generate rotation transformation, and the three-axis directions of the coordinate systems are as follows:
When the straight line axis Z1 returns to zero, the relative offset between the origin of the coordinate system X 3Y3Z3 and the origin of the machine coordinate system in the X, Y, Z axis direction is a constant value, which is expressed as (d x,dy,-dz).
When the linear axis Z1 moves, the relative position between the origin of the coordinate system X 3Y3Z3 and the origin of the machine coordinate system in the Z-axis direction changes, the feedback displacement of the Z-axis encoder 10 of the linear axis Z1 is represented by P z, the origin position of the coordinate system X 3Y3Z3 can be represented by (d x,dy,-dz+Pz), the vector distance from the fixed point of the laser 15 to the laser focus is also a constant value, and the direction is represented by L Laser and parallel to the Z-axis direction of the machine coordinate system.
Step S 113: the calculation expression for determining the coordinate position of the laser focus in the machine tool coordinate system is as follows:
Wherein: (d x,dy,-dz) represents the relative offset of the origin of the coordinate system X 3Y3Z3 and the origin of the machine coordinate system in the X, Y, Z axis direction, respectively, and P z represents the feedback displacement of the Z-axis encoder 10 of the linear axis Z1; l Laser represents the vector distance of the fixed point of the laser 15 to the laser focus, and the vector direction of L Laser is parallel to the Z-axis direction of the machine coordinate system.
Specifically, in step S 120, the defining the workpiece sub-chain and calculating the transformation matrix from the laser coordinate system to the workpiece coordinate system specifically includes:
step S 121: the workpiece sub-chain consists of a linear axis Y3, a linear axis X4, a rotating shaft B5, a rotating shaft C6 and a workpiece 7 placed on the upper surface of the rotating shaft C6 in sequence;
Step S 122: establishing a base coordinate system X 0Y0Z0 on the turntable, representing the translational motion of the X, Y axis by the motion of the base coordinate system, wherein the base coordinate system does not perform rotation transformation;
Step S 123: the coordinate system X 1Y1Z1,Z1 is fixedly connected with the rotating shaft B5, the axis of the coordinate system X 1Y1Z1,Z1 coincides with the axis of the rotating shaft B5, and the origin of the coordinate system X 1Y1Z1 is positioned at the intersection point of the B, C axis;
The coordinate system X 2Y2Z2,Z2 is fixedly connected with the rotating shaft C6, the axis of the coordinate system X 2Y2Z2 is coincident with the axis of the rotating shaft C6, and the origin of the coordinate system X 2Y2Z2 is positioned at the center of the upper surface of the turntable;
Step S 124: the workpiece coordinate system w is completely coincident with the coordinate system X 2Y2Z2, and the workpiece coordinate system w is transformed along with the transformation of the coordinate system X 2Y2Z2;
Step S 125: and determining a transformation matrix formula of the position relation of the adjacent connecting rods according to robot kinematics.
In a specific embodiment of the present invention, the derivation process of the workpiece sub-chain is as follows:
the workpiece sub-chain is composed of a linear axis Y3, a linear axis X4, a rotary shaft B5, a rotary shaft C6 and a workpiece 7 placed on the upper surface of the rotary shaft C6 in sequence, wherein the last item on the sub-chain is placed on the former item and is influenced by the motion of the former item, so that a kinematic chain structure is formed.
What needs to be specifically stated is: wherein the rotation axis B5 rotates on the XZ plane and the rotation axis C6 rotates on the XY plane.
Because X, Y axes of the machine tool only drive the turntable to do translational motion, a base coordinate system X 0Y0Z0 is established on the turntable, the translational motion of X, Y axes is represented by the motion of the base coordinate system X 0Y0Z0, the base coordinate system does not perform rotary transformation, and when each axis of the machine tool returns to zero, the origin of the base coordinate system is positioned at the origin of the machine tool coordinate system.
The axis of the coordinate system X 1Y1Z1,Z1 is fixedly connected with the rotating shaft B5, the axis coincides with the axis of the rotating shaft B5, and the origin point of the axis coincides with the intersection point of the axis of the B, C shafts.
The axis of the coordinate system X 2Y2Z2,Z2 fixedly connected with the rotary shaft C6 coincides with the axis of the rotary shaft C6, and the origin is positioned at the center of the upper surface of the turntable.
The object coordinate system w is fully coincident with the coordinate system X 2Y2Z2, and the latter is transformed to transform.
When B, C rotation axis returns to zero, coordinate system X 0Y0Z0 coincides with XYZ axis direction of coordinate system X 1Y1Z1.
Specifically, in the embodiment of the present invention, in step S 125, the transformation matrix formula R i of the adjacent link positional relationship is:
Where α i-1 denotes a deflection angle from Z i-1 to Z i with respect to the direction of X i-1, a i-1 denotes a displacement from Z i-1 to Z i in the direction of X i-1, θ i denotes a deflection angle from X i-1 to X i with respect to the direction of Z i, d i denotes a displacement from X i-1 to X i in the direction of Z i, θ B denotes a B-axis encoder 11 feedback displacement of the rotation axis B5, θ C denotes a C-axis encoder 12 feedback displacement of the rotation axis C6, and d denotes a distance between an intersection point of the rotation axis B5 with the axis of the rotation axis C6 and an origin of the workpiece coordinate system.
In this step, the parameters of the D-H matrix can be listed as shown in Table 1.
TABLE 1D-H matrix parameters table
According to robot kinematics, a transformation matrix formula R i of the position relationship of adjacent connecting rods is as follows:
The feedback displacements of the X-axis encoder 8 of the linear axis X and the Y-axis encoder 9 of the linear axis Y are denoted by P x、Py, respectively, and the transformation matrix R 0 from the machine coordinate system to the base coordinate system is:
The transformation matrix R 1 from the base coordinate system to the coordinate system X 1Y1Z1 is:
the transformation matrix R 2 from coordinate system X 1Y1Z1 to coordinate system X 2Y2Z2 is:
specifically, in step S 120 of the present invention, the coordinate system X 2Y2Z2 coincides with the object coordinate system. According to the laser sub-chain, a transformation matrix T Stock from a machine tool coordinate system to a workpiece coordinate system is obtained as follows:
TStock＝R0×R1×R2
Wherein: r 0 represents a transformation matrix from a machine tool coordinate system to a base coordinate system; r 1 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2; r 2 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2.
Specifically, in step S 130 of the present invention, the motion model of the obtained laser focus under the workpiece coordinate system is:
Wherein Q' Laser is the coordinate position of the laser focus under the workpiece coordinate system.
Specifically, in step S 300, the calculating the moving distance of the laser focus in the current function period under the workpiece coordinate system specifically includes:
Step S 310: comparing the position Q 'Laser(x1,y1,z1) of the laser focus in the workpiece coordinate system at the current time with the position Q' 0(x0,y0,z0 of the laser focus in the workpiece coordinate system at the previous time;
Step S 320: the vector distance of the laser focus travelling in the current function period is calculated as follows:
Wherein: x 1 represents the x-axis coordinate of the laser focus at the current time in the workpiece coordinate system, y 1 represents the y-axis coordinate of the laser focus at the current time in the workpiece coordinate system, and z 1 represents the z-axis coordinate of the laser focus at the current time in the workpiece coordinate system; x 0 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, y 0 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, and z 0 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the previous time.
Specifically, in step S 400, the obtaining, by small line segment fitting, the current total distance of the laser 15 on the three-dimensional curved surface includes:
Step S 410: calling a laser pulse output function in the motion controller 13, wherein the calling period is 1ms;
step S 420: and summing the processing vector distances obtained in each function call period to obtain the current total processing distance.
Specifically, in this step S 400, the processing vector distances obtained in each function call period are summed to obtain the current total processing distance, the laser pulse output function is called in the PLC program of the motion controller 13, the call period is 1ms, and the calculated track length is considered to be approximately equal to the actual value because the call period of the function is sufficiently short.
Specifically, in step S 500, in each function call period, the comparing output according to the calculated total distance of laser processing specifically includes:
step S 510: judging whether the calculated total distance of laser processing is an integer multiple of a set interval value or not in each function calling period;
Step S 520: if the total laser processing distance is an integer multiple of the set interval value, starting a timer, outputting a high level by the motion controller 13, enabling the laser 15 to output a pulse, and closing the timer after a period of time;
Step S 530: if the total distance of laser processing is not an integer multiple of the set interval value, the motion controller 13 outputs a low level to stop the output of the laser 15.
It should be specifically noted that, in the embodiment of the present invention, the spot interval output by the laser 15 may be directly specified, without considering the repetition frequency and the processing speed of the laser 15, so that the complexity of the operation is reduced.
In addition, in the embodiment of the invention, the laser 15 with fixed frequency is adopted for processing, the processing cost is not required to be increased, a motion model is built for the traditional five-axis machine tool in the calculation process of the processing distance, the method has certain universality, and when the method is used, only part of machine tool parameters are required to be modified on the industrial personal computer 14, and the method can be applied to the five-axis machine tool in an externally-hung mode.
Although the present disclosure is disclosed above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the scope of the invention.
Claims (10)
1. A synchronous output method for the equidistant laser pulse positions of a three-dimensional curved surface is characterized by comprising the following steps:
S 100: constructing a motion model of the laser focus under a workpiece coordinate system;
S 200: in each function call period, the current displacement of each axis of the five-axis machine tool is obtained through an encoder;
s 300: calculating the moving distance of the laser focus under the coordinate system of the workpiece in the current function period;
S 400: obtaining the current total processing distance of the laser on the three-dimensional curved surface through small line segment fitting;
S 500: and in each function calling period, comparing and outputting according to the calculated total distance of laser processing.
2. The method for synchronously outputting the laser pulse positions at equal intervals on the three-dimensional curved surface according to claim 1, wherein in step S 100, the construction of the motion model of the laser focus under the coordinate system of the workpiece specifically includes:
Step S 110: defining a laser sub-chain, and deducing the coordinate position of a laser focus under a machine tool coordinate system;
Step S 120: defining a workpiece sub-chain, and calculating a conversion matrix from a laser coordinate system to a workpiece coordinate system;
step S 130: and obtaining a motion model of the laser focus under the coordinate system of the workpiece.
3. The method for synchronously outputting the laser pulse positions at equal intervals on the three-dimensional curved surface according to claim 2, wherein in step S 110, the defining the laser sub-chain and deriving the coordinate position of the laser focus in the machine coordinate system specifically includes the steps of:
Step S 111: the laser sub-chain consists of a linear axis Z and a laser, and the laser is fixed on the linear axis Z;
Step S 112: respectively placing a coordinate system X 3Y3Z3 and X 4Y4Z4 at a fixed point and a laser focus position of the laser, wherein the XYZ axis directions of the coordinate system are consistent with the three-axis directions of a machine tool coordinate system, and rotation transformation does not occur;
step S 113: the calculation expression for determining the coordinate position of the laser focus in the machine tool coordinate system is as follows:
Wherein: (d x,dy,-dz) represents the relative offset of the origin of the coordinate system X 3Y3Z3 and the origin of the machine coordinate system in the direction of X, Y, Z axis, respectively, and P z represents the encoder feedback displacement of the linear axis Z; l Laser represents the vector distance of the fixed point of the laser to the laser focus, and the vector direction of L Laser is parallel to the Z-axis direction of the machine coordinate system.
4. The method for synchronously outputting the positions of the equidistant laser pulses on the three-dimensional curved surface according to claim 3, wherein the method is characterized by comprising the following steps: in step S 120, the defining the workpiece sub-chain and calculating the transformation matrix from the laser coordinate system to the workpiece coordinate system specifically includes:
Step S 121: the workpiece sub-chain consists of a linear axis Y, a linear axis X, a rotating shaft B, a rotating shaft C and workpieces placed on the upper surface of the rotating shaft C in sequence;
Step S 122: establishing a base coordinate system X 0Y0Z0 on the turntable, representing the translational motion of the X, Y axis by the motion of the base coordinate system, wherein the base coordinate system does not perform rotation transformation;
Step S 123: the coordinate system X 1Y1Z1,Z1 is fixedly connected with the rotating shaft B, the axis of the coordinate system X 1Y1Z1,Z1 coincides with the axis of the rotating shaft B, and the origin of the coordinate system X 1Y1Z1 is positioned at the intersection point of the axis of the B, C shaft;
The coordinate system X 2Y2Z2,Z2 is fixedly connected with the rotating shaft C, the axis of the coordinate system X 2Y2Z2 is coincident with the axis of the rotating shaft C, and the origin of the coordinate system X 2Y2Z2,Z2 is positioned at the center of the upper surface of the turntable;
Step S 124: the workpiece coordinate system w is completely coincident with the coordinate system X 2Y2Z2, and the workpiece coordinate system w is transformed along with the transformation of the coordinate system X 2Y2Z2;
Step S 125: and determining a transformation matrix formula of the position relation of the adjacent connecting rods according to robot kinematics.
5. The method for synchronously outputting the positions of the equidistant laser pulses on the three-dimensional curved surface according to claim 4, wherein the method is characterized by comprising the following steps: in step S 125, the transformation matrix formula R i of the adjacent link positional relationship is:
Wherein α i-1 represents a deflection angle from Z i-1 to Z i with respect to the direction of X i-1, a i-1 represents a displacement from Z i-1 to Z i in the direction of X i-1, θ i represents a deflection angle from X i-1 to X i with respect to the direction of Z i, d i represents a displacement from X i-1 to X i in the direction of Z i, θ B represents an encoder feedback displacement of the rotation axis B, θ C represents an encoder feedback displacement of the rotation axis C, and d represents a distance between an intersection point of the rotation axis B with the axis of the rotation axis C and an origin of the workpiece coordinate system.
6. The method according to claim 5, wherein in step S 120, according to the laser sub-chain, the transformation matrix T Stock from the machine coordinate system to the workpiece coordinate system is:
TStock＝R0×R1×R2
Wherein: r 0 represents a transformation matrix from a machine tool coordinate system to a base coordinate system; r 1 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2; r 2 represents a transformation matrix from the coordinate system X 1Y1Z1 to the coordinate system X 2Y2Z2.
7. The method for synchronously outputting the three-dimensional curved surface equidistant laser pulse positions according to claim 6, wherein in step S 130, the obtained motion model of the laser focus under the workpiece coordinate system is:
Wherein Q' Laser is the coordinate position of the laser focus under the workpiece coordinate system.
8. The method for synchronously outputting the laser pulse positions at equal intervals on the three-dimensional curved surface according to claim 1, wherein in step S 300, the calculating the moving distance of the laser focus in the current function period under the workpiece coordinate system specifically includes:
Step S 310: comparing the position Q 'Laser(x1,y1,z1) of the laser focus in the workpiece coordinate system at the current time with the position Q' 0(x0,y0,z0 of the laser focus in the workpiece coordinate system at the previous time;
Step S 320: the vector distance of the laser focus travelling in the current function period is calculated as follows:
Wherein: x 1 represents the x-axis coordinate of the laser focus at the current time in the workpiece coordinate system, y 1 represents the y-axis coordinate of the laser focus at the current time in the workpiece coordinate system, and z 1 represents the z-axis coordinate of the laser focus at the current time in the workpiece coordinate system; x 0 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, y 0 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the previous time, and z 0 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the previous time.
9. The method for synchronously outputting the equidistant laser pulse positions of the three-dimensional curved surface according to claim 1, wherein in step S 400, the step of obtaining the current total distance of the laser on the three-dimensional curved surface by fitting small line segments specifically comprises:
step S 410: calling a laser pulse output function in a motion controller, wherein the calling period is 1ms;
step S 420: and summing the processing vector distances obtained in each function call period to obtain the current total processing distance.
10. The method for synchronously outputting the laser pulse positions at equal intervals on the three-dimensional curved surface according to claim 1, wherein in step S 500, the comparing and outputting according to the calculated total distance of laser processing in each function call period specifically includes:
step S 510: judging whether the calculated total distance of laser processing is an integer multiple of a set interval value or not in each function calling period;
Step S 520: if the total laser processing distance is integral multiple of the set interval value, starting a timer, outputting a high level by a motion controller, enabling the laser to output pulses, and closing the timer after a period of time;
Step S 530: if the total distance of the laser processing is not integral multiple of the set interval value, the motion controller outputs a low level so as to stop the output of the laser.
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