A composite five-axis printing method, system and control method thereof

Abstract

The present invention discloses a composite five-axis printing method, system, and control method thereof. The composite five-axis printing method comprises: determining whether there is fill interference between the inner and outer contours of a model based on the number of intersections between hatches and inner and outer contour polygons; scaling the contour edges using a scaling algorithm; hatching the scaled new model, determining a fill path based on the intersections between hatches and plane contours; and when there is fill interference between the inner and outer contours, not extruding the fill path within the inner contour. The angle change of each fill layer is calculated based on the total number of skeleton points. Path points are added between paired inner and outer contour intersections based on a certain length standard. A normal vector perpendicular to an adjacent tangent plane is drawn from each two adjacent points to form a trapezoid, and the extrusion amount of the line segment between the two adjacent points is determined based on the area of ​​the trapezoid. The present invention is suitable for fill printing of models with complex inner and outer contours.

Description

Technical Field

[0001] The present invention relates to 3D printing, and in particular to a composite five-axis printing method, system and control method thereof. Background Art

[0002] Traditional 3D printing is limited to flat surfaces, and the print head maintains a fixed position relative to the workpiece during the printing process. This results in a stair-step effect on curved surfaces, the need for supports when printing overhanging structures, and low surface quality. Five-axis additive printing adds two degrees of freedom to traditional 3D printing, enabling support-free three-dimensional printing of models by rotating the 3D object. Most existing five-axis printing methods are only capable of five-axis path planning and printing for single-contour models, making it difficult to print infill with complex internal and external contours. Five-axis printing with segmentation algorithms is only capable of segmenting and infilling models with small bends, but struggles with support-free infill printing for models with large bends. Essentially, it still relies on uniform infill printing along three axes, failing to address the variable layer thickness requirements associated with angular variations. Printed models can suffer from uneven internal stresses, and excessive angular variations can even cause structural deformation. For complex multi-contour models, the interference caused by multiple contours infill is an even more challenging issue. Summary of the Invention

[0003] Purpose of the invention: The first purpose of the present invention is to provide a composite five-axis printing method capable of realizing variable layer thickness filling of inner and outer contours. The second purpose of the present invention is to provide a composite five-axis printing system. The third purpose of the present invention is to provide a control method for the composite five-axis printing system.

[0004] Technical Solution: The composite five-axis printing method of the present invention includes STL model input, extraction of model skeleton points, calculation of model cutting plane parameters, model slicing, coordinate transformation of slice data, and G-code output. The model is a complex model with internal and external contours, and the composite five-axis printing method further includes the following operations between the model slicing and slice data coordinate transformation steps:

[0005] Determine whether there is fill interference between the inner and outer contours of the model: The point data generated by model slicing is used to form a set of point contours based on the principle of minimum adjacent distance. After fitting the point contour set to generate inner and outer contour polygons, the number of intersections between the shadow lines and the inner and outer contour polygons is determined by intersecting the shadow lines. If the number of intersections is greater than 2, there is fill interference between the inner and outer contours.

[0006] Scale the contour edges using a scaling algorithm to avoid conflicts between the fill path and the contour print extrusion;

[0007] The scaled new model is hatched and the filling path is determined based on the intersection of the hatch and the plane contour. When there is interference between the inner and outer contour filling, the part of the filling path located within the inner contour is not extruded and filled.

[0008] Calculation of the extrusion amount of the filling line segment of the model with variable layer thickness: The angle change of each layer of filling is calculated based on the total number of skeleton points. Based on a certain length standard, path points are added between the intersection points of the inner contour and the outer contour in pairs. For every two adjacent points, the normal vector perpendicular to the upper adjacent tangent plane forms a trapezoid. The extrusion amount of the line segment between the two adjacent points is determined according to the area of ​​the trapezoid, so that the printing of contours of unequal thickness can be achieved.

[0009] Furthermore, the process of obtaining the set of point contours is as follows: for the first point read by the model, copy an identical point to the point array, use the distance formula between two points to calculate the point with the smallest distance except for its own point and move the first point to the new array; the point with the smallest distance calculates the new array in turn, and the last point is closed with the first point to generate the contour of the polygon; when there are multiple contour points inside and outside, there will be some points left in the array, and a new round of iteration is performed to generate a set of multiple contour points.

[0010] Furthermore, the contour edge is scaled by a scaling algorithm, including:

[0011] In the scaling algorithm, for each point pm2(x2,y2), take its two adjacent points pm1(x1,y1) and pm3(x3,y3), pm1 and pm2 form a vector pm2 and pm3 form a vector

[0012] vector Normalized normal vector for:

[0013]

[0014] Two normal vectors Average value for:

[0015]

[0016] Calculating vectors The module b:

[0017]

[0018] Pair Vector After normalization, we get the vector

[0019] Calculates two vectors The dot product c = (x1-x2)·(x3-x2)+(y3-y2)·(y1-y2)

[0020] Calculate two vectors The angle α between them:

[0021]

[0022] Actual required displacement ratio delta is the manually set scaling distance;

[0023] The displacement vector of point pm2 is The displaced point pm2' is the scaled point.

[0024] Furthermore, the filling path is configured as follows: sorting in sequence according to the number of hatching lines, the end endpoints where the adjacent odd-numbered hatching lines intersect with the model contour and the end endpoints where the even-numbered hatching lines intersect with the contour constitute the tail filling path, and the starting endpoints where the adjacent even-numbered hatching lines intersect with the model contour and the starting endpoints where the odd-numbered hatching lines intersect with the contour constitute the filling path.

[0025] Furthermore, the calculation of the extrusion amount of the model variable layer thickness filling line segment includes:

[0026] According to the total number of skeleton points w, calculate the angle change of each layer of filling The slope value of the hatch line in the next layer is replaced by k' = tan(B + bh), where B is the angle between the hatch line and the x-axis;

[0027] The extrusion amount of the line segment between two adjacent points is J=K2·S, where S is the area of ​​the corresponding trapezoid and K2 is the extrusion coefficient, which is set and adjusted according to the accuracy requirements of the model wire.

[0028] The composite five-axis printing system described in the present invention includes a host computer control system and a slave computer five-axis 3D printing execution system, wherein the host computer control system includes a PC-side CPU control system, a five-axis slicing algorithm module and a Raspberry Pi control system, and the five-axis slicing algorithm module is used to obtain G code according to the composite five-axis printing method; the PC-side CPU control system and the Raspberry Pi control system are used to collaboratively control the slave computer five-axis 3D printing execution system, including the transmission of G code, online monitoring of five-axis 3D printing information and real-time control of five-axis 3D printing; the slave computer five-axis 3D printing execution system includes a display module and a WiFi communication module for communicating with the host computer control system. The display module is integrated by the Raspberry Pi and is used to display a real-time picture of the printing process captured by a camera, and is also used to display the operation control interface and printing progress of the host computer control system, and can directly issue control instructions to the slave computer five-axis 3D printing execution system in a touch screen manner.

[0029] Furthermore, the lower machine five-axis 3D printing execution system also includes a five-axis linkage motion control module, a limit switch module to avoid stepper motor movement collision, a dual-nozzle extrusion system capable of composite material extrusion printing, and a heating module for pre-treatment heating before printing;

[0030] The five-axis linkage motion control module includes an X-axis stepper motor driver for controlling the direction and speed of the X-axis stepper motor, a Y-axis stepper motor driver for controlling the direction and speed of the Y-axis stepper motor, a Z-axis stepper motor driver for controlling the direction and speed of the Z-axis stepper motor, a U-axis stepper motor driver for controlling the direction and speed of the U-axis stepper motor, and a V-axis stepper motor driver for controlling the direction and speed of the V-axis stepper motor;

[0031] The dual-nozzle extrusion system includes dual filament feed ends, nozzle 1, nozzle 2, extruder 1 stepper motor, extruder 2 stepper motor and a heat dissipation unit. The extruder stepper motor is driven by the corresponding extruder driver. The printing filament enters from the filament feed end and is driven by the extruder stepper motor and extruded from the nozzle for additive printing. The heat dissipation unit is used to cool the throat of the five-axis printer.

[0032] The heating module includes nozzle 1, nozzle 2 and a hot bed capable of adjusting temperature;

[0033] The limit switch module includes X-axis limit switch, Y-axis limit switch, Z-axis limit switch, U-axis Hall sensor limit switch and V-axis limit switch, which are used to find the zero position of the X, Y, Z, U and V axes, and to limit the movement of the X, Y, Z, U and V axes to the extreme positions.

[0034] Furthermore, the heat dissipation unit includes a heat dissipation fan and a fan speed regulator, and the fan speed regulator is used to adjust the rotation speed of the heat dissipation fan.

[0035] Furthermore, the five-axis 3D printing execution system of the lower computer has a USB input port for directly transmitting the G code to the display module to realize the instruction control of the five-axis 3D printing execution system of the lower computer.

[0036] The control method of the composite five-axis printing system of the present invention includes:

[0037] S1. Modeling in the host computer control system;

[0038] S2. Obtain G code according to the composite five-axis printing method, and output the G code to the PC CPU control system and the Raspberry Pi control system;

[0039] S3, the PC CPU control system or the Raspberry Pi control system sends the G code to the lower computer five-axis 3D printing execution system through the WiFi communication module. According to the processing instructions, the lower computer five-axis 3D printing execution system works and prints the model according to the planned processing trajectory;

[0040] During the processing, the PC CPU control system and the Raspberry Pi control system monitor the printing, and the printing status is displayed on the display module. When the printing environment requirements change, the PC CPU control system or the Raspberry Pi control system can be used for control and the next step instructions can be issued according to the printing requirements; after the printing is normal and matches the requirements, the printing is successful.

[0041] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: The present invention solves the filling interference problem caused by internal and external contours through interference discussion, contour scaling, variable layer thickness filling calculation, etc. of complex internal and external contour models. It can support filling printing of models with complex internal and external contours, and solves the problem of structural deformation that may be caused by unreasonable filling extrusion in five-axis printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a flowchart of a composite five-axis printing method provided by an embodiment of the present invention;

[0043] Figure 2 Schematic diagram of the relationship between point scaling vectors in an embodiment of the present invention;

[0044] Figure 3 Schematic diagram of the relationship between hatch intercept and angle in an embodiment of the present invention;

[0045] Figure 4 Schematic diagram of the relationship between the variable layer thickness extrusion amount trapezoid and the intersection point in an embodiment of the present invention;

[0046] Figure 5 1 is a schematic structural diagram of a composite five-axis printing system provided by an embodiment of the present invention;

[0047] Figure 6 This is a flow chart of a control method for a composite five-axis printing system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the accompanying drawings.

[0049] Combine Figure 1 ,The existing five-axis printing method includes STL model input, ,extraction of the model’s skeleton points, calculation of the ,model’s cutting plane parameters, model slicing, coordinate transformation of ,slicing data, and output of G code, which cannot be applied to ,complex models with internal and external contours.

[0050] To this end, the present invention improves upon existing five-axis printing methods and provides a composite five-axis printing method applicable to models with complex internal and external contours. Specifically, the present invention performs the following operations between the model slicing and slice data coordinate transformation steps in existing five-axis printing methods:

[0051] 1) Determine whether there is fill interference between the inner and outer contours of the model

[0052] After slicing the model, the point data generated by the model slicing is used to form a set of point contours using the principle of minimum adjacent distance. The process of obtaining the point contour set is as follows: for the first point read by the model, copy an identical point to the point array, use the distance formula between two points to calculate the point with the smallest distance except for its own point and move the first point to the new array; the point with the smallest distance is calculated on the new array in turn, and the last point is closed with the first point to generate the contour of the polygon; when there are multiple contour points inside and outside, there will be some points left in the array, and a new round of iteration is performed to generate a set of multiple contour points.

[0053] Any two points (x i ,y i )、(x j ,y j ) is calculated as follows:

[0054] At this point, the point data generated by slicing has been transformed in space, equivalent to the Xoy two-dimensional plane in space. After fitting the point outline set to generate the inner and outer contour polygons, the number of intersections between the shadow lines and the inner and outer contour polygons is determined by intersecting the hatches. The number of intersections determines the number of inner and outer contours and whether there is fill interference. Specifically, if the number of intersections is greater than 2, there is fill interference between the inner and outer contours.

[0055] 2) Scale the contour edges through the scaling algorithm to avoid conflicts between the fill path and the contour print extrusion

[0056] In the scaling algorithm, such as Figure 2 As shown, for each point pm2(x2,y2), take its two adjacent points pm1(x1,y1) and pm3(x3,y3), pm1 and pm2 form a vector pm2 and pm3 form a vector

[0057] vector Normalized normal vector for:

[0058]

[0059] Two normal vectors Average value for:

[0060]

[0061] Calculating vectors The module b:

[0062]

[0063] Pair Vector After normalization, we get the vector

[0064] Calculates two vectors The dot product c = (x1-x2)·(x3-x2)+(y3-y2)·(y1-y2)

[0065] Calculate two vectors The angle α between them:

[0066]

[0067] Actual required displacement ratio delta is the manually set scaling distance;

[0068] The displacement vector of point pm2 is The displaced point pm2' is the scaled point.

[0069] The displacement vector calculated by the scaling algorithm ensures that the displacement maintains a certain ratio, avoiding excessive or insufficient movement, thereby preventing the problem of point sorting disorder caused by the close distance between adjacent points when scaling.

[0070] 3) Fill the scaled new model with hatching, and determine the filling path based on the intersection of the hatching and the plane contour. When there is interference between the inner and outer contour filling, the part of the filling path located within the inner contour is not extruded and filled;

[0071] like Figure 3 As shown, the intersection point is calculated by intersecting the shadow line y=kx+deltab with the plane contour. The k value of the first layer is given. The tangent point is calculated and the maximum intercept b.max and the minimum intercept b.min of the shadow line and the y-axis can be obtained. At this time, the tangent point between the shadow line with the maximum intercept and the contour is B1.

[0072] Calculate the intercept of adjacent hatches based on the given gap between adjacent hatches Angle A in the figure is 45° (this angle is only exemplary and can be other angles);

[0073] The triangle is tangent and we can get A=B, and the angles of the two angles A and B are equal. The given k value can be calculated

[0074] The total shadow can be further calculated The number of bars is n, rounded to an integer.

[0075] For each hatch line that meets the above constraints, the odd-numbered intersection points and the even-numbered intersection points constitute a filled path, thereby avoiding the interference caused by multiple layers of contours.

[0076] The fill path is configured as follows: hatches are sorted sequentially by number. The end points of adjacent odd-numbered hatches intersecting the model outline and the end points of adjacent even-numbered hatches intersecting the outline form the tail fill path. The beginning points of adjacent even-numbered hatches intersecting the model outline and the beginning points of adjacent odd-numbered hatches intersecting the outline form the fill path. For example, hatch line 1 intersects the end point of hatch line 2, and hatch line 2 intersects the beginning point of hatch line 3. However, hatch line 1 does not intersect the beginning point of hatch line 2, and hatch line 2 does not intersect the end point of hatch line 3. Each pair of points forms a fill path of varying lengths due to the varying inner and outer contours.

[0077] 4) Calculation of extrusion volume of filling line segments with variable layer thickness

[0078] The angle change of each filling layer is calculated by the total number of skeleton points. According to a certain length standard, path points are added between the intersection points of the inner and outer contours. For every two adjacent points, the normal vector perpendicular to the upper adjacent tangent plane is drawn to form a trapezoid. The extrusion amount of the line segment between the two adjacent points is determined according to the area of ​​the trapezoid to achieve the printing of contours of unequal thickness.

[0079] Specifically, according to the total number of skeleton points w, the angle change of each layer of filling is calculated The next layer's hatch slope k value is replaced by k'=tan(B+bh); by changing the k value, the stability of the printed structure is ensured. B is the angle between the hatch and the x-axis, which can be calculated from the hatch slope.

[0080] Combine Figure 4 The intersection points of each hatch line and the contour are arranged in order. The odd and even points arranged in order form a group of two, and no points in each group are identical. Path points are added between each group of odd and even points with a length of 1 mm. Figure 4 The midpoints H, G, and C are the points inserted between the odd point B and the even point A. For every two adjacent points, a perpendicular line is drawn to the upper adjacent tangent plane to form a trapezoid, with the intersection of the hatching and the outer contour at B (a1, b1, c1), and the adjacent point H (a2, b2, c2).

[0081] The equation of every plane above is A1(x-x0)+B2(y-y0)+C(z-z0)=0.

[0082] The length of line segment BH

[0083] Draw a normal line perpendicular to the upward plane between point B and point H, and we can get the distance between the two line segments h and i as follows:

[0084]

[0085] According to the formula for the sides of a right triangle, we can get the height of the trapezoid, which is the distance between endpoints J and I:

[0086] The area of ​​the trapezoid is further calculated to be

[0087] The distance between the outer contour endpoint and the perpendicular line of the normal vector of the adjacent point is not fixed, and the height distance of the remaining trapezoids is 1mm, which further simplifies the calculation. Figure 2 When the midpoints G, H, K, and J form a trapezoid with an area of ​​S2, there is no need to calculate the distance between point J and point K, which is the height of the trapezoid.

[0088] The extrusion rate of line segment HB is J = K2·S, where K2 is the extrusion coefficient and is adjusted based on the required precision of the model filament. By calculating the extrusion rate, it is possible to achieve reasonable extrusion printing of contours of varying thicknesses, ultimately completing infill printing of complex models.

[0089] Existing five-axis printers lack data collection and monitoring during the printing process. This makes it difficult for researchers to develop and control their functions as the printing environment changes. This results in poor processing adaptability of the printing platform and an inability to integrate functions to meet specific processing requirements in specific situations. This leads to cumbersome processing and increased time costs. Furthermore, existing five-axis printers often use a single host computer system for control and single-material printing, making implementation cumbersome and unstable.

[0090] To this end, the embodiment of the present invention also provides a composite five-axis printing system, such as Figure 5 As shown, the system includes a host control system and a slave five-axis 3D printing execution system, wherein the host control system includes a PC CPU control system, a five-axis slicing algorithm module, and a Raspberry Pi control system. The five-axis slicing algorithm module is used to obtain G-code according to the composite five-axis printing method described in an embodiment of the present invention. The PC CPU control system and the Raspberry Pi control system communicate via a communication port to collaboratively control the slave five-axis 3D printing execution system, including G-code transmission, online monitoring of five-axis 3D printing information, and real-time control of five-axis 3D printing. After receiving the G-code transmitted by the five-axis slicing algorithm module, the PC CPU control system and the Raspberry Pi control system send control instructions to the slave five-axis 3D printing execution system to drive the slave five-axis 3D printing execution system to operate.

[0091] The lower-level five-axis 3D printing execution system includes a display module, a WiFi communication module, a five-axis linkage motion control module, a limit switch module to avoid stepper motor movement collision, a dual-nozzle extrusion system capable of composite material extrusion printing, a heating module for pre-treatment heating before printing, and a CPU integrated control board.

[0092] The CPU integrated control board consists of a main CPU motherboard and a CPU expansion board. The X-axis, Y-axis, and Z-axis stepper motors are connected to the main CPU motherboard, while the U-axis and V-axis stepper motors are connected to the CPU expansion board. A WiFi communication module is integrated into the CPU integrated control board. The lower-level five-axis 3D printing execution system uses the WiFi communication module to achieve real-time communication with the Raspberry Pi control system and the PC CPU control system.

[0093] The five-axis motion control module includes an X-axis stepper motor driver for controlling the direction and speed of the X-axis stepper motor, a Y-axis stepper motor driver for controlling the direction and speed of the Y-axis stepper motor, a Z-axis stepper motor driver for controlling the direction and speed of the Z-axis stepper motor, a U-axis stepper motor driver for controlling the direction and speed of the U-axis stepper motor, and a V-axis stepper motor driver for controlling the direction and speed of the V-axis stepper motor. The X-, Y-, Z-, U-, and V-axis stepper motor drivers are connected to the CPU integrated control board. The stepper driver outputs feed back operating status signals of the X-, Y-, Z-, U-, and V-axis stepper motors to the upper computer via the lower computer. The upper computer makes decisions based on these feedback signals and sends control commands to the lower computer. The lower computer then adjusts the operating status of the X-, Y-, Z-, U-, and V-axis stepper motors via the stepper driver inputs.

[0094] The display module, integrated with a Raspberry Pi, displays the real-time image of the printing process captured by the camera. It also displays the upper control system's operation interface and printing progress, allowing for monitoring of printing status. Users can directly issue control commands to the lower computer's five-axis 3D printing execution system via the touchscreen.

[0095] The dual-nozzle extrusion system includes dual filament feed ends, nozzle 1, nozzle 2, extruder 1 stepper motor, extruder 2 stepper motor and a heat dissipation unit. Extruder 1 stepper motor and extruder 2 stepper motor are connected to the CPU motherboard. The extruder stepper motor is driven by the corresponding extruder driver. The printing filament enters from the filament feed end and is extruded by the nozzle under the drive of the extruder stepper motor for additive printing. In this embodiment, the dual-nozzle extrusion system can print composite materials. The heat dissipation unit is used to cool the throat of the five-axis printer and includes a cooling fan and a fan speed regulator. The fan speed regulator is used to adjust the speed of the cooling fan.

[0096] The heating module includes nozzle 1, nozzle 2 and a heated bed that can be temperature-adjusted. The five-axis printing execution system receives instructions from the host computer control system through the WiFi communication module to adjust the temperatures of nozzle 1, nozzle 2 and the heated bed.

[0097] The limit switch module includes X-axis limit switch, Y-axis limit switch, Z-axis limit switch, U-axis Hall sensor limit switch and V-axis limit switch, all of which are connected to the CPU integrated control board. They are used by the five-axis printing execution system to find the zero position of the X, Y, Z, U, and V axes, and to limit the movement of the X, Y, Z, U, and V axes to the extreme positions.

[0098] The CPU integrated control board is also connected to a USB input port, which can directly transmit the G code to the display module through USB input, realizing the command control of the lower computer's five-axis 3D printing execution system, simplifying the operating steps of the PC-side control system and overcoming the closed nature of the traditional five-axis single control system.

[0099] like Figure 6 As shown, an embodiment of the present invention further provides a control method of the composite five-axis printing system according to an embodiment of the present invention, comprising:

[0100] S1, modeling through the host computer control system;

[0101] S2. Obtain G code according to the composite five-axis printing method according to an embodiment of the present invention, and output the G code to the PC CPU control system and the Raspberry Pi control system;

[0102] S3, the PC CPU control system or the Raspberry Pi control system sends the G code to the lower computer five-axis 3D printing execution system through the WiFi communication module. According to the processing instructions, the lower computer five-axis 3D printing execution system works and prints the model according to the planned processing trajectory;

[0103] During the processing, the PC CPU control system and the Raspberry Pi control system monitor the printing, and the printing status is displayed on the display module. When the printing environment requirements change, for example, printing needs to be temporarily stopped, the PC CPU control system or the Raspberry Pi control system can be used to control and issue the next instruction according to the printing requirements; after the printing is normal and matches the requirements, the printing is successful.

[0104] The composite five-axis printing system provided by this invention uses a combined control system consisting of a PC-based online control system and a Raspberry Pi control system to enable real-time monitoring of the printing status. This system controls the five-axis 3D printing execution system in real time based on changes in the printing environment. This overcomes the closed nature of traditional single-control systems, reduces the cumbersome steps involved, and offers advantages of openness and portability. The dual-nozzle extrusion system supports the printing of composite materials, providing scalability in the printed model.

Claims

1. A composite five-axis printing method, comprising STL model input, extraction of model skeleton points, calculation of model cutting plane parameters, model slicing, coordinate transformation of slicing data and output of G code, characterized in that: The model is a complex model with internal and external contours. The composite five-axis printing method further includes performing the following operations between the steps of model slicing and coordinate transformation of the sliced ​​data: Determine whether there is fill interference between the inner and outer contours of the model: The point data generated by model slicing is used to form a set of point contours based on the principle of minimum adjacent distance. After fitting the point contour set to generate inner and outer contour polygons, the number of intersections between the shadow lines and the inner and outer contour polygons is determined by intersecting the shadow lines. If the number of intersections is greater than 2, there is fill interference between the inner and outer contours. Scale the contour edges using a scaling algorithm to avoid conflicts between the fill path and the contour print extrusion; The scaled new model is hatched and the filling path is determined based on the intersection of the hatch and the plane contour. When there is interference between the inner and outer contour filling, the part of the filling path located within the inner contour is not extruded and filled. Calculation of line segment extrusion for variable layer thickness filling: The angle change of each layer of filling is calculated based on the total number of skeleton points. Path points are added between the intersection points of the inner and outer contours according to a certain length standard. A normal line perpendicular to the upper tangent plane is drawn from every two adjacent points to form a trapezoid. The extrusion amount of the line segment between the two adjacent points is determined based on the area of ​​the trapezoid, thus enabling the printing of contours of varying thickness. Calculation of extrusion volume of filled line segments with variable layer thickness, including: According to the total number of skeleton points w, calculate the angle change of each layer of filling The slope value of the hatch line in the next layer is replaced by k' = tan(B + bh), where B is the angle between the hatch line and the x-axis; The extrusion amount of the line segment between two adjacent points is J=K2·S, where S is the area of ​​the corresponding trapezoid and K2 is the extrusion coefficient, which is set and adjusted according to the accuracy requirements of the model wire.

2. The composite five-axis printing method according to claim 1, characterized in that: The process of obtaining the set of point contours is as follows: the first point read by the model is copied to the point array, and the point with the smallest distance except for its own point is calculated using the distance formula between two points, and the first point is moved out to the new array; the point with the smallest distance is calculated on the new array in turn, and the last point is closed with the first point to generate the contour of the polygon; when there are multiple contour points inside and outside, there will be some points left in the array, and a new round of iteration is performed to generate a set of multiple contour points.

3. The composite five-axis printing method according to claim 1, characterized in that: Scale the silhouette edges using a scaling algorithm, including: In the scaling algorithm, for each point pm2(x2,y2), take its two adjacent points pm1(x1,y1) and pm3(x3,y3), pm1 and pm2 form a vector pm2 and pm3 form a vector vector Normalized normal vector for: Two normal vectors Average value for: Calculating vectors The module b: Pair Vector After normalization, we get the vector Calculates two vectors The dot product c = (x1-x2)·(x3-x2)+(y3-y2)·(y1-y2) Calculate two vectors The angle α between them: Actual required displacement ratio delta is the manually set scaling distance; The displacement vector of point pm2 is The displaced point pm2' is the scaled point.

4. The composite five-axis printing method according to claim 1, characterized in that: The fill path is configured as follows: sort the lines in sequence according to the number of hatches, and the end endpoints where the adjacent odd-numbered hatches intersect with the model outline and the end endpoints where the even-numbered hatches intersect with the outline constitute the tail fill path; the start endpoints where the adjacent even-numbered hatches intersect with the model outline and the start endpoints where the odd-numbered hatches intersect with the outline constitute the fill path.

5. A composite five-axis printing system, characterized in that: The invention comprises an upper computer control system and a lower computer five-axis 3D printing execution system, wherein the upper computer control system comprises a PC-side CPU control system, a five-axis slicing algorithm module and a Raspberry Pi control system, and the five-axis slicing algorithm module is used to obtain G code according to the composite five-axis printing method described in any one of claims 1 to 4; the PC-side CPU control system and the Raspberry Pi control system are used to collaboratively control the lower computer five-axis 3D printing execution system, including the transmission of G code, online monitoring of five-axis 3D printing information and real-time control of five-axis 3D printing; the lower computer five-axis 3D printing execution system comprises a display module and a WiFi communication module for communicating with the upper computer control system, the display module is integrated by the Raspberry Pi, and is used to display the real-time picture of the printing process captured by the camera, and is also used to display the operation control interface and printing progress of the upper computer control system, and can directly issue control instructions to the lower computer five-axis 3D printing execution system in a touch screen manner.

6. The composite five-axis printing system according to claim 5, characterized in that: The lower machine's five-axis 3D printing execution system also includes a five-axis linkage motion control module, a limit switch module to prevent stepper motor movement collisions, a dual-nozzle extrusion system capable of composite material extrusion printing, and a heating module for pre-treatment heating before printing. The five-axis linkage motion control module includes an X-axis stepper motor driver for controlling the direction and speed of the X-axis stepper motor, a Y-axis stepper motor driver for controlling the direction and speed of the Y-axis stepper motor, a Z-axis stepper motor driver for controlling the direction and speed of the Z-axis stepper motor, a U-axis stepper motor driver for controlling the direction and speed of the U-axis stepper motor, and a V-axis stepper motor driver for controlling the direction and speed of the V-axis stepper motor; The dual-nozzle extrusion system includes dual filament feed ends, nozzle 1, nozzle 2, extruder 1 stepper motor, extruder 2 stepper motor and a heat dissipation unit. The extruder stepper motor is driven by the corresponding extruder driver. The printing filament enters from the filament feed end and is driven by the extruder stepper motor and extruded from the nozzle for additive printing. The heat dissipation unit is used to cool the throat of the five-axis printer. The heating module includes nozzle 1, nozzle 2 and a hot bed capable of adjusting temperature; The limit switch module includes X-axis limit switch, Y-axis limit switch, Z-axis limit switch, U-axis Hall sensor limit switch and V-axis limit switch, which are used to find the zero position of the X, Y, Z, U and V axes, and to limit the movement of the X, Y, Z, U and V axes to the extreme positions.

7. The composite five-axis printing system according to claim 6, characterized in that: The heat dissipation unit includes a heat dissipation fan and a fan speed regulator, and the fan speed regulator is used to adjust the speed of the heat dissipation fan.

8. The composite five-axis printing system according to claim 6, characterized in that: The lower computer five-axis 3D printing execution system has a USB input port for directly transmitting the G code to the display module to realize the command control of the lower computer five-axis 3D printing execution system.

9. A control method for a composite five-axis printing system according to any one of claims 5 to 8, characterized in that: include: S1. Modeling in the host computer control system; S2. Obtaining G code according to the composite five-axis printing method according to any one of claims 1 to 4, and outputting the G code to a PC CPU control system and a Raspberry Pi control system; S3, the PC CPU control system or the Raspberry Pi control system sends the G code to the lower computer five-axis 3D printing execution system through the WiFi communication module. According to the processing instructions, the lower computer five-axis 3D printing execution system works and prints the model according to the planned processing trajectory; During the processing, the PC CPU control system and the Raspberry Pi control system monitor the printing, and the printing status is displayed on the display module. When the printing environment requirements change, the PC CPU control system or the Raspberry Pi control system can be used for control and the next step instructions can be issued according to the printing requirements; after the printing is normal and matches the requirements, the printing is successful.

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