CN118513678A - Synchronous output method for equidistant laser pulse positions of three-dimensional curved surface - Google Patents

Abstract

The present invention discloses a method for synchronously outputting equally spaced laser pulse positions on a three-dimensional curved surface, and relates to the technical field of laser cutting of a five-axis machine tool. The output method comprises the steps of: constructing a spatial motion model of the laser focus in a workpiece coordinate system; obtaining the current displacement of each axis of the five-axis machine tool through an encoder in each function call cycle; calculating the current coordinates of the laser focus in the workpiece coordinate system according to the axis position feedback obtained by the encoder, and comparing it with the calculated last coordinate position to obtain the vector distance of the laser focus in the workpiece coordinate system during this cycle; obtaining the total processing length of the laser on the three-dimensional curved surface by fitting a small line segment; and comparing and outputting the calculated total laser processing length in each function call cycle. The present invention ensures the uniformity of the light spot when laser cutting brittle materials without increasing the cost, so that the light spot overlap rate is not affected by the laser scanning speed, and improves the processing quality and efficiency.

Description

A method for synchronous output of equally spaced laser pulse positions on three-dimensional surfaces

Technical Field

The invention relates to the field of five-axis machine tool laser cutting, and in particular to a method for synchronously outputting equally spaced laser pulse positions on a three-dimensional curved surface.

Background Art

Laser processing has the advantages of non-contact and high instantaneous power, so it is gradually applied to the cutting field of brittle materials. When using the crack control method to cut brittle materials, it is necessary to ensure that there is a stable laser energy input on the cutting path. The consistent spot overlap ratio on the cutting path can improve the uniformity of laser energy distribution, thereby improving the cutting quality.

In the prior art, a stable spot overlap ratio is generally ensured by controlling the scanning speed or repetition frequency. Specifically, the spot interval s depends on the laser repetition frequency f and the scanning speed v, that is, s = v/f. When the laser repetition frequency is fixed, the laser scanning speed on the cutting path is kept constant; or a variable frequency laser is used to change the laser output frequency at the same time when the scanning speed changes. However, if the scanning speed is kept constant, in the actual processing process, especially when cutting complex spatial surfaces, the speed constraints of the machine tool's rotating axis and linear axis will greatly limit the upper limit of the scanning speed, thereby reducing the processing efficiency; if an adjustable frequency laser is used, the cost is increased, and the laser output power changes, affecting the processing technology.

Summary of the invention

In view of the technical problems that the solutions for ensuring the uniformity of the light spots in the prior art have low processing efficiency and increased processing costs, the present invention provides a method for synchronously outputting equally spaced laser pulse positions on three-dimensional surfaces, which can ensure that the light spot overlap ratio during laser cutting is not affected by the scanning speed without increasing the cost, thereby improving the quality and efficiency of laser pulse processing.

In order to solve the above problems, the present invention provides a method for synchronously outputting equally spaced laser pulse positions on a three-dimensional curved surface, the output method comprising the steps of:

S ₁₀₀ : Constructing the motion model of the laser focus in the workpiece coordinate system;

S ₂₀₀ : In each function call cycle, the current displacement of each axis of the five-axis machine tool is obtained through the encoder;

S ₃₀₀ : Calculate the moving distance of the laser focus in the workpiece coordinate system during the current function cycle;

S ₄₀₀ : Get the total processing distance of the laser on the three-dimensional surface through small line segment fitting;

S ₅₀₀ : In each function call cycle, a comparison output is performed based on the calculated total laser processing distance.

Furthermore, in step _S100 , constructing a motion model of the laser focus in the workpiece coordinate system specifically includes:

Step _S110 : define the laser sub-chain and derive the coordinate position of the laser focus in the machine tool coordinate system;

Step _S120 : define the workpiece sub-chain and calculate the transformation matrix from the laser coordinate system to the workpiece coordinate system;

Step _S130 : Obtaining a motion model of the laser focus in the workpiece coordinate system.

Furthermore, in step _S110 , the step of defining the laser sub-chain and deriving the coordinate position of the laser focus in the machine tool coordinate system specifically includes the following steps:

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 _S112 : _Coordinate systems _X3Y3Z3 and _X4Y4Z4 are placed at the fixed point of the laser and the laser focus position respectively, _and the _XYZ axis directions of the coordinate systems are consistent with the three-axis directions of the machine tool coordinate system, _and no rotation transformation occurs;

Step _S113 : The calculation expression for determining the coordinate position of the laser focus in the machine tool coordinate system is as follows:

Wherein: ( _dx , _dy , _-dz ) represents the relative offset between the origin of _coordinate system _X3Y3Z3 and the origin of machine _tool coordinate system in the X, Y, and Z axis directions respectively; _Pz represents the encoder feedback displacement of linear axis Z; _LLaser represents the vector distance from the fixed point of the laser to the laser focus, and the vector direction of _LLaser is parallel to the Z axis direction of the machine tool coordinate system.

Furthermore, in step _S120 , the definition of the workpiece sub-chain and the calculation of the transformation matrix from the laser coordinate system to the workpiece coordinate system specifically include:

Step _S121 : The workpiece sub-chain is composed of the linear axis Y, the linear axis X, the rotation axis B, the rotation axis C, and the workpiece placed on the upper surface of the rotation axis C in sequence;

Step _S122 : Establish a base coordinate system _X0Y0Z0 on the turntable _{, and} use the movement of the base coordinate system to represent the translation movement of the X and Y axes. The base coordinate system does not undergo rotation transformation;

Step _S123 : Fix the _coordinate system _X1Y1Z1 to the rotation axis B, _{the Z1 axis} coincides with the axis of the rotation axis B, _and the origin of the coordinate system _X1Y1Z1 is located at the intersection of the axes of the B _and C axes;

The coordinate system X ₂ Y ₂ Z ₂ is fixed to the rotation axis C, the Z ₂ axis coincides with the axis of the rotation axis C, and the origin of the coordinate system X ₂ Y ₂ Z ₂ is located at the center of the upper surface of the turntable;

Step _S124 : the workpiece coordinate system w completely overlaps with the coordinate system _{X2Y2Z2 , and} the workpiece coordinate system w transforms with the transformation of _{the coordinate} system _X2Y2Z2 ;

Step _S125 : According to robot kinematics, determine the transformation matrix formula of the position relationship of adjacent links.

Furthermore, in step _S125 , the transformation matrix formula R _i of the position relationship of adjacent connecting rods is:

Among them, α _i-1 represents the deflection angle from Zi _-1 to _Zi about the Xi _-1 direction, a _i-1 represents the displacement from Zi _-1 to _Zi along the Xi _-1 direction, θ _i represents the deflection angle from Xi _-1 to _Xi about the _Zi direction, d _i represents the displacement from Xi _-1 to _Xi along the _Zi direction, θ _B represents the encoder feedback displacement of the rotating axis B, θ _C represents the encoder feedback displacement of the rotating axis C, and d represents the distance between the intersection of the axes of rotating axes B and C and the origin of the workpiece coordinate system.

Further, in step _S120 , according to the laser sub-chain, the transformation matrix T _Stock from the machine tool coordinate system to the workpiece coordinate system is:

T _Stock = R ₀ × R ₁ × R ₂

Among them: _R0 represents _the transformation matrix _from the machine tool coordinate system to the base coordinate system; _R1 represents _the transformation matrix from the coordinate system _X1Y1Z1 to the coordinate system _X2Y2Z2 ; _R2 represents _the transformation matrix from _{the coordinate system X1Y1Z1 to the coordinate system X2Y2Z2 .}

Furthermore, in step _S130 , the motion model of the laser focus in the workpiece coordinate system is obtained as follows:

Wherein, Q′ _Laser is the coordinate position of the laser focus in the workpiece coordinate system.

Furthermore, in step _S300 , the calculation of the moving distance of the laser focus in the workpiece coordinate system during the current function cycle specifically includes:

Step _S310 : Compare the current position _Q'Laser ( _x1 , _y1 , _z1 ) of the laser focus in the workpiece coordinate system with the previous position _Q'0 ( _x0 , _y0 , _z0 ) of the laser focus in the workpiece coordinate system;

Step _S320 : Calculate the vector distance of the laser focus in the current function cycle as:

Wherein: _x1 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the current moment, _y1 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the current moment, and _z1 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the current moment; _x0 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment, _y0 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment, and _z0 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment.

Furthermore, in step _S400 , the total processing distance of the laser on the three-dimensional surface currently obtained by fitting the small line segments specifically includes:

Step _S410 : calling the laser pulse output function in the motion controller, with a calling period of 1 ms;

Step _S420 : summing up the processing vector distances obtained in each function call cycle to obtain the current total processing distance.

Further, in step _S500 , the comparison output according to the calculated total laser processing distance in each function call cycle specifically includes:

Step _S510 : In each function call cycle, determine whether the calculated total laser processing distance is an integer multiple of the set interval value;

Step _S520 : If the total laser processing distance is an integer multiple of the set interval value, the timer is turned on, the motion controller outputs a high level, the laser outputs pulses, and the timer is turned off after a period of time;

Step _S530 : If the total laser processing distance is not an integer multiple of the set interval value, the motion controller outputs a low level to stop the laser output.

Compared with the prior art, the present invention has the following beneficial effects:

1. The method for synchronous output of equally spaced laser pulse positions on a three-dimensional curved surface described in the present application is to construct a spatial motion model of the laser focus in the workpiece coordinate system; in each function call cycle, the current displacement of each axis of the five-axis machine tool is obtained through the encoder; according to the axis position feedback obtained by the encoder, the current coordinate of the laser focus in the workpiece coordinate system is calculated, and compared with the calculated previous coordinate position to obtain the vector distance of the laser focus in the workpiece coordinate system during this cycle; through small line segment fitting, the total processing length of the laser on the three-dimensional curved surface is obtained; in each function call cycle, the total processing length of the laser is compared and output. The current total processing distance of the laser focus is calculated according to the axis displacement parameter fed back by the encoder, thereby controlling the switching light of the laser, so that the output position of the laser pulse is not affected by the scanning speed. When processing complex trajectories, the scanning speed can be changed according to the situation of each trajectory segment while ensuring the consistency of the spot interval, which greatly improves the laser processing efficiency; in actual processing, some unavoidable acceleration and deceleration situations, such as acceleration and deceleration at the beginning and end of the trajectory, will no longer change the spot overlap ratio on the cutting trajectory, thereby improving the processing quality.

2. It can ensure the uniformity of the light spot acting on the surface of the material when laser cutting brittle materials without increasing the cost, so that the overlap rate of the light spot on the trajectory is not affected by the laser scanning speed, while improving the processing quality and efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a flow chart of a method for synchronously outputting equally spaced laser pulse positions on a three-dimensional curved surface according to an embodiment of the present invention;

FIG2 is a detailed flow chart of step _S100 in an embodiment of the present invention;

FIG3 is a detailed flow chart of step _S120 in an embodiment of the present invention;

FIG4 is a schematic structural diagram of a dual-turntable five-axis machine tool according to an embodiment of the present invention;

FIG5 is a schematic diagram of a control mechanism of a laser pulse output system according to an embodiment of the present invention;

FIG6 is a structural diagram of two open chains of a machine tool according to an embodiment of the present invention;

7 is a schematic diagram of the coordinate system position on the workpiece sub-chain in an embodiment of the present invention;

FIG8 is a schematic diagram of the coordinate system position on the laser sub-chain in an embodiment of the present invention;

FIG. 9 is a schematic diagram of laser program operation control of a dual-turntable five-axis machine tool in an embodiment of the present invention.

Description of reference numerals:

1-Linear axis Z; 2-Laser focus; 3-Linear axis Y; 4-Linear axis X; 5-Rotation axis B; 6-Rotation axis C; 7-Workpiece; 8-X-axis encoder; 9-Y-axis encoder; 10-Z-axis encoder; 11-B-axis encoder; 12-C-axis encoder; 13-Motion controller; 14-Industrial computer; 15-Laser.

DETAILED DESCRIPTION

The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

In the prior art, laser processing is widely used in the field of cutting brittle materials. During use, a stable spot overlap ratio is generally ensured by controlling the laser scanning speed or repetition frequency, that is, the spot interval s depends on the repetition frequency f and the scanning speed v of the laser 15, that is, s = v/f. When the repetition frequency of the laser 15 is fixed, the scanning speed of the laser on the cutting path remains unchanged; or a variable frequency laser 15 is used, and when the scanning speed changes, the laser output frequency is changed at the same time.

However, if the laser 15 maintains a constant scanning speed, during the actual processing, especially when cutting complex spatial surfaces, the speed constraints of the machine tool's rotating axis and linear axis will greatly limit the upper limit of the scanning speed, thereby reducing the processing efficiency; if an adjustable frequency laser is used, the cost is increased and the laser output power changes, affecting the processing technology.

To solve the above technical problems, please refer to Figures 1-9, an embodiment of the present invention provides a method for synchronously outputting equally spaced laser pulse positions on a three-dimensional curved surface, and the synchronous output method comprises the steps of:

S ₁₀₀ : Constructing the motion model of the laser focus in the workpiece coordinate system;

In this step, when constructing the spatial motion model of the laser focus in the workpiece coordinate system, this embodiment uses the machine tool coordinate system as an intermediate quantity and is divided into three steps.

S ₂₀₀ : In each function call cycle, the current displacement of each axis of the five-axis machine tool is obtained through the encoder;

In this step, the current displacement of each axis obtained by the encoder is substituted into the above motion model to obtain the coordinate position of the laser focus in the workpiece coordinate system during each function call cycle.

S ₃₀₀ : Calculate the moving distance of the laser focus in the workpiece coordinate system during the current function cycle;

S ₄₀₀ : Obtaining the total processing distance of the laser 15 on the three-dimensional surface by fitting small line segments;

S ₅₀₀ : In each function call cycle, a comparison output is performed based on the calculated total laser processing distance.

The embodiment of the present invention calculates the current total processing distance of the laser focus 2 according to the axis displacement parameter fed back by the encoder, thereby controlling the switch of the laser 15, so the output position of the laser pulse is not affected by the scanning speed.

When processing complex trajectories, the scanning speed can be changed according to the conditions of each trajectory segment while ensuring the consistency of the spot interval, which greatly improves the laser processing efficiency. In actual processing, some unavoidable acceleration and deceleration conditions, such as acceleration and deceleration at the beginning and end of the trajectory, will no longer change the spot overlap ratio on the cutting trajectory, thereby improving the processing quality.

Specifically, referring to FIG. 2 , in step _S100 of the present invention, the construction of the motion model of the laser focus in the workpiece coordinate system specifically includes:

Step _S110 : define the laser sub-chain and derive the coordinate position of the laser focus in the machine tool coordinate system.

Step _S120 : define the workpiece sub-chain and calculate the transformation matrix from the laser coordinate system to the workpiece coordinate system.

Step _S130 : Obtaining a motion model of the laser focus in the workpiece coordinate system.

From the perspective of kinematics, there is an open chain structure similar to that of a robotic arm from the machine tool coordinate system to the laser focus, and from the machine tool coordinate system to the workpiece coordinate system, which are called the laser sub-chain and the workpiece sub-chain respectively.

The axis is regarded as the connecting rod and joint structure of the robot arm. According to the D-H convention, a coordinate system is fixed to each moving axis of the machine tool. Through the translation and rotation transformation of the coordinate system, the two sub-chains (laser sub-chain and workpiece sub-chain) are derived respectively, and the motion model of the laser focus in the workpiece coordinate system can be obtained.

Specifically, referring to FIG. 3 , in step _S110 of the present invention, the steps of defining the laser sub-chain and deriving the coordinate position of the laser focus in the machine tool coordinate system specifically include the following steps:

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 _S112 : _Coordinate systems _X3Y3Z3 and _X4Y4Z4 are placed at the fixed point of the laser 15 and the laser focus position respectively _{, and} the _XYZ axis directions of the coordinate systems are consistent with the three axis directions of the machine tool coordinate system, and no rotation transformation occurs.

The derivation process of the laser sub-chain 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.

Coordinate systems X ₃ Y ₃ Z ₃ and X ₄ Y ₄ Z ₄ are placed at the fixed point of the laser 15 and the laser focus position, respectively. The XYZ axis directions of the coordinate systems are consistent with the three-axis directions of the machine tool coordinate system and no rotation transformation occurs, wherein:

After the linear axis Z1 returns to zero, the relative offset between the origin of the coordinate system _X3Y3Z3 and _the origin of the machine tool coordinate system in the X _, Y, and Z axis directions is a constant, expressed as ( _dx , _dy , _-dz ).

When the linear axis Z1 moves, the relative position _of the origin of the coordinate system _X3Y3Z3 and _the origin of the machine tool 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 _Pz . The origin position of the coordinate system _X3Y3Z3 can be expressed as ( _dx , _dy , _{-dz + Pz} ). The vector distance from the fixed point of the laser ₁₅ to the laser focus is also a constant, represented by L _Laser , and its direction is parallel to the Z-axis direction of the machine tool coordinate system.

Step _S113 : The calculation expression for determining the coordinate position of the laser focus in the machine tool coordinate system is as follows:

Wherein: ( _dx , _dy , _-dz ) represents the relative offset between the origin of the coordinate system _X3Y3Z3 and _the origin of the machine _tool coordinate system in the X, Y, and Z axis directions respectively; _Pz represents the feedback displacement of the Z-axis encoder 10 of the linear axis Z1; L _Laser represents the vector distance from 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 tool coordinate system.

Specifically, in step _S120 , the definition of the workpiece sub-chain and the calculation of the transformation matrix from the laser coordinate system to the workpiece coordinate system specifically include:

Step _S121 : The workpiece sub-chain is composed of the linear axis Y3, the linear axis X4, the rotation axis B5, the rotation axis C6 and the workpiece 7 placed on the upper surface of the rotation axis C6 in sequence;

Step _S122 : Establish a base coordinate system _X0Y0Z0 on the turntable _{, and} use the movement of the base coordinate system to represent the translation movement of the X and Y axes. The base coordinate system does not undergo rotation transformation;

Step _S123 : Fix the _coordinate system _X1Y1Z1 to the rotation axis B5, _{the Z1 axis} coincides with the axis of the rotation axis B5, _{and the origin of the coordinate system X1Y1Z1 is located} at the intersection of the axes of the B and C axes;

The coordinate system X ₂ Y ₂ Z ₂ is fixed to the rotation axis C6, the Z ₂ axis coincides with the axis of the rotation axis C6, and the origin of the coordinate system X ₂ Y ₂ Z ₂ is located at the center of the upper surface of the turntable;

Step _S124 : the workpiece coordinate system w completely coincides with the coordinate system _{X2Y2Z2 , and} the workpiece coordinate system w _is transformed along with the transformation of _the coordinate system _X2Y2Z2 ;

Step _S125 : According to robot kinematics, determine the transformation matrix formula of the position relationship of adjacent links.

In a specific embodiment of the present invention, the derivation process of the workpiece subchain is as follows:

The workpiece sub-chain is composed of the linear axis Y3, the linear axis X4, the rotation axis B5, the rotation axis C6 and the workpiece 7 placed on the upper surface of the rotation axis C6 in sequence. The latter item on the sub-chain is placed on the previous item and is affected by the movement of the previous item, thus forming a kinematic chain structure.

It should be particularly noted that the rotation axis B5 rotates on the XZ plane, and the rotation axis C6 rotates on the XY plane.

Since the X and Y axes of the machine tool only drive the turntable to do translational motion, _a base coordinate system _X0Y0Z0 is established on the _{turntable . The movement of the base coordinate system X0Y0Z0 represents} the translational motion of the X and _Y axes. The base coordinate system does not perform rotational transformation. When the axes of the machine tool return to zero, the origin of the base coordinate system is located at the origin of the machine tool coordinate system.

The _coordinate system _X1Y1Z1 is fixed to the rotation axis B5, _{the Z1} axis coincides with the axis of the rotation axis B5, and its origin is located at the intersection of the B and C axis axes.

The coordinate system X ₂ Y ₂ Z ₂ is fixed to the rotation axis C6, the Z ₂ axis coincides with the axis of the rotation axis C6, and its origin is located at the center of the upper surface of the turntable.

The workpiece coordinate system w completely coincides with the coordinate system X ₂ Y ₂ Z ₂ and is transformed by the transformation of the latter.

When the B and C rotation axes return to zero, the XYZ axis directions of the coordinate system X ₀ Y ₀ Z ₀ are consistent with those of the coordinate system X ₁ Y ₁ Z ₁ .

Specifically, in a specific embodiment of the present invention, in step _S125 , the transformation matrix formula R _i of the position relationship of adjacent connecting rods is:

Among them, α _i-1 represents the deflection angle from Zi _-1 to _Zi about the Xi _-1 direction, a _i-1 represents the displacement from Zi _-1 to _Zi along the Xi _-1 direction, θ _i represents the deflection angle from Xi _-1 to _Xi about the _Zi direction, d _i represents the displacement from Xi _-1 to _Xi along the _Zi direction, θ _B represents the feedback displacement of the B-axis encoder 11 of the rotating axis B5, θ _C represents the feedback displacement of the C-axis encoder 12 of the rotating axis C6, and d represents the distance between the intersection of the axes of the rotating axis B5 and the rotating axis C6 and the 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 1 Parameters of D-H matrix

According to robot kinematics, the transformation matrix formula R _i of the position relationship of adjacent links 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 represented by P _x and P _y respectively, and the transformation matrix R ₀ from the machine tool coordinate system to the base coordinate system is:

The transformation matrix R ₁ from the base coordinate system to the coordinate system X ₁ Y ₁ Z ₁ is:

The transformation matrix R ₂ from coordinate system X ₁ Y ₁ Z ₁ to coordinate system X ₂ Y ₂ Z ₂ is:

Specifically, in step _S120 of the present invention, the coordinate system _{X2Y2Z2 coincides} with the workpiece coordinate system _. According to the laser subchain, the transformation matrix T _Stock from the machine tool coordinate system to the workpiece coordinate system is obtained as follows:

T _Stock = R ₀ × R ₁ × R ₂

Among them: _R0 represents _the transformation matrix _from the machine tool coordinate system to the base coordinate system; _R1 represents _the transformation matrix from the coordinate system _X1Y1Z1 to the coordinate system _X2Y2Z2 ; _R2 represents _the transformation matrix from _{the coordinate system X1Y1Z1 to the coordinate system X2Y2Z2 .}

Specifically, in step _S130 of the present invention, the motion model of the laser focus in the workpiece coordinate system is obtained as follows:

Wherein, Q′ _Laser is the coordinate position of the laser focus in the workpiece coordinate system.

Specifically, in step _S300 , the calculation of the moving distance of the laser focus in the workpiece coordinate system during the current function cycle specifically includes:

Step _S310 : Compare the current position _Q'Laser ( _x1 , _y1 , _z1 ) of the laser focus in the workpiece coordinate system with the previous position _Q'0 ( _x0 , _y0 , _z0 ) of the laser focus in the workpiece coordinate system;

Step _S320 : Calculate the vector distance of the laser focus in the current function cycle as:

Wherein: _x1 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the current moment, _y1 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the current moment, and _z1 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the current moment; _x0 represents the x-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment, _y0 represents the y-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment, and _z0 represents the z-axis coordinate of the laser focus in the workpiece coordinate system at the previous moment.

Specifically, in step _S400 , the total processing distance of the laser 15 on the three-dimensional surface currently obtained by fitting the small line segments specifically includes:

Step _S410 : calling the laser pulse output function in the motion controller 13, with a calling period of 1 ms;

Step _S420 : summing up the processing vector distances obtained in each function call cycle to obtain the current total processing distance.

Specifically, in step _S400 , the processing vector distance obtained in each function call cycle is summed to obtain the current total processing distance, and the laser pulse output function is called in the PLC program of the motion controller 13 with a calling cycle of 1 ms. Since the function calling cycle is short enough, it is considered that the calculated trajectory length is approximately equal to the actual value.

Specifically, in step _S500 , in each function call cycle, comparing and outputting the calculated total laser processing distance specifically includes:

Step _S510 : In each function call cycle, determine whether the calculated total laser processing distance is an integer multiple of the set interval value;

Step _S520 : If the total laser processing distance is an integer multiple of the set interval value, the timer is turned on, the motion controller 13 outputs a high level, and the laser 15 outputs pulses. After a period of time, the timer is turned off;

Step _S530 : If the total laser processing distance is not an integer multiple of the set interval value, the motion controller 13 outputs a low level to stop the laser 15 from outputting.

It should be particularly noted that in the embodiment of the present invention, the spot interval output by the laser 15 can be directly specified without considering the repetition frequency and processing speed of the laser 15, thereby reducing the complexity of the operation.

In addition, in the embodiment of the present invention, a fixed-frequency laser 15 is used for processing without increasing the processing cost. A motion model is constructed for a traditional five-axis machine tool during the calculation of the processing distance. The method has a certain degree of versatility. When in use, only some machine tool parameters need to be modified on the industrial computer 14, and it can be applied to the five-axis machine tool in the form of a plug-in.

Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present 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,d_y,-d_z) 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:

T_Stock＝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.