Multiaxial 3D printing device for metal structural component and arc-based additive manufacturing method

Abstract

To provide a multiaxial 3D printing device for metal structural components and an arc-based additive manufacturing method.SOLUTION: Based on a multiaxial coordinated printing mode of a robot arm device, a movable guide rail device, and a positioner device, expansion of a six-axis robot arm enables printing in a robot arm's free posture and moving a guide rail enables movable printing following an axis along the guide rail, an open motion space of the 3D printing robot is enlarged, a two-axis positioner allows achieving multiaxial 3D printing without support for complex metal structural components, reducing material costs, and simplifying post-processing. Simultaneously, linkage linear interpolation through a world coordinate system allows effective controlling printing accuracy and print accuracy and large-format dimensions and further achieving multiaxial 3D printing for large and complex metal structural components.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention belongs to the technical fields of structural engineering and 3D printing, and particularly relates to a multi-axis 3D printing device for metal structural parts and an arc-based additive manufacturing method.

Background Art

[0002] Metal 3D printing, also known as metal additive manufacturing, has advantages such as high efficiency and high precision compared to conventional metal manufacturing processes and is suitable for processing and manufacturing complex metal structural parts. However, in metal 3D printing, in order to ensure the success of printing, metal structural parts need to meet the corresponding manufacturing constraints. Among many manufacturing constraints, the limitation of the overhang effect caused by gravity is one of the main constraints in metal 3D printing. The overhang effect means that when the angle between the boundary of the structure and the horizontal plane is smaller than the critical value, due to the existence of gravity, the metal material will collapse during the deposition process for each layer, which will affect the printing quality and may also lead to the failure of printing the structural parts.

[0003] An effective way to overcome the overhang effect is, from the perspective of structural design, to introduce angle constraints into the optimal design of the metal structure to obtain an optimal configuration that meets the manufacturing constraints of the angle. In the metal 3D printing of conventional 3-axis robots, a self-supporting structure that meets the manufacturing constraints can be obtained to avoid waste of support, but in many cases, it will result in a significant increase in material consumption and a significant decrease in structural performance.

[0004] With the rapid development of the machinery industry, the multi-axis 3D printing technology for metal structural parts is widely used in fields such as aerospace and vehicle engineering. The multi-axis 3D printer for metal structural parts with more than three axes is equipped with a free-rotating base and can dynamically adjust the printing direction during the printing process to avoid the overhang effect, which effectively solves the problems of the increase in the volume of the self-supporting structure of the three-axis 3D printing of metal structural parts and the significant decline in performance. Therefore, the reasonable and effective design and construction of the multi-axis robotic 3D printing device for metal structural parts is an important prerequisite for integrating the optimal design and manufacturing of complex structures.

[0005] In summary, it is necessary to study the multi-axis 3D printing device and arc-based additive manufacturing method for metal structural parts, adapt to the additive manufacturing of complex and long metal structural parts, expand the size range of the printed metal structural parts, save the printing cost of the support structure, and recognize the need to print complex additive metal structural parts without support.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The purpose of the present invention is to overcome the disadvantages of the prior art and provide a multi-axis 3D printing device and an arc-based additive manufacturing method for metal structural parts.

Means for Solving the Problems

[0007] This multi-axis 3D printing device for metal structural parts includes a six-axis industrial robot, a bottom base, a power supply device for additive manufacturing, and a moving guide rail device. The bottom of the six-axis industrial robot is rotatably connected to the bottom base, and the six-axis industrial robot and the bottom base constitute a robot arm device. The bottom of the power supply device for additive manufacturing and the bottom of the robot arm device are fixed to a support base plate, and the support base plate moves along the length direction of the moving guide rail device. A welding gun is fixed to the tip of the six-axis industrial robot, and the power supply device for additive manufacturing is connected to the welding gun via a wire supply tube. On one side of the moving guide rail device, a combined workbench is installed in combination with a two-axis positioner. The combined workbench is a long workbench parallel to the moving guide rail device. The two-axis positioner includes a rotating axis and a reversing axis. The rotation angle of the rotating axis is an unlimited angle, but the reversing angle of the reversing axis is a limited angle. A rotating disk is installed on the upper surface of the two-axis positioner. The metal structural parts are arranged on the combined workbench or the rotating disk. The moving guide rail device and the two-axis positioner respectively control the driving of the corresponding first axis and second axis through external axis motors.

[0008] Preferably, the moving guide rail device includes a moving guide rail, a guide rail crawler, and a guide rail support. Both sides of the moving guide rail device are anchor-fixed to the ground through the guide rail support. The moving guide rail is installed along the entire length on both sides of the moving guide rail device. The guide rail crawler is connected to the support base plate, and the guide rail crawler is engaged and connected with the moving guide rail.

[0009] Preferably, the power supply device for additive manufacturing includes a CMT welding machine, a wire reel, a wire supply tube, a welding gun, an electric control box, and a cleaner. The welding gun is fixed to the tip of a six-axis industrial robot. The cleaner is arranged directly below the electric control box to form an integrated device. The bottoms of the electric control box, the cleaner, and the CMT welding machine are fixed to the support base plate, and the wire reel is fixed to the CMT welding machine.

[0010] Preferably, an integrated control cabinet, a teaching pendant, a visual operation console, and a wire cutting machine are installed on the ground outside the moving guide rail device. The integrated control cabinet is arranged to control the movement of a total of nine axes of the six-axis industrial robot, the moving guide rail device, and the two-axis positioner. The visual operation console is arranged to perform visual control and online monitoring of the printing process. The wire cutting machine is installed with a spatter prevention spray device and a welding slag cleaning device.

[0011] Preferably, the two-axis positioner is located at the end of one side of the movable guide rail device, a combination worktable is installed on the same side within the length of the corresponding movable guide rail device, a protective gas cylinder is installed on the ground on the other side of the movable guide rail device, and the protective gas cylinder supplies gas to the welding gun through a long gas pipe, the wire cutting machine and the purifier are arranged according to the position of the six-axis industrial robot, an arc prevention plate is surrounded around the multi-axis 3D printing device for metal structural parts, and the integrated control cabinet, the teaching pendant, and the visual operation console are arranged outside the arc prevention plate.

[0012] The arc-type additive manufacturing method of such a multi-axis 3D printing machine for metal structural parts is Step S1 of designing a 3D model of a metal structural part; When the 3D model is introduced into the slice path planning software, a step S2 of providing a specific print program by the slice path planning software; Step S3 of introducing a print program into the control software and installing a slice path for the model by the control software; According to the characteristics of the metal structural parts, it is selected to print with a two-axis positioner or to print with a combination worktable. When it is selected to print with a rotating disk, the six-axis industrial robot, the moving guide rail device, and the two-axis positioner move in conjunction with each other. When it is selected to print with a combination worktable, the six-axis industrial robot and the moving guide rail device move in conjunction with each other. and step S5 of melting the metal wire with the arc of the welding gun to perform multi-axis 3D printing of the metal structural part.

[0013] Preferably, the integrated control cabinet controls the rotation of the rotary axis and the inverted axis of the two-axis positioner in real time according to the program planning path, so that when printing any member of the structural part, the printing angle of the part is always equal to or greater than the critical printing angle, and the metal structural part on the rotating disk can overcome the gravity overhang effect.

[0014] Preferably, the process of the program planning path algorithm includes the division of the printing area, the calculation of the local optimal printing direction, and the angle adjustment of the printing direction, as follows: Divide the structural part into the printing area and calculate the local optimal printing direction θ i Set the overhang critical angle θ, and when θ i ≥ θ, print directly; when θ i < θ, the overhang effect due to gravity occurs, adjust the two moving axes of the biaxial positioner, and make the adjusted local optimal printing direction θ i ’ ≥ θ, and with θ i ’ = 90° as the vertical direction, realize multi-axis 3D printing without a support structure. The local optimal printing direction is determined by the inclination direction of the boundary unit in the printing sub-area. The inclination direction of the structural boundary is the angle between the boundary and the X-axis. The convolution kernel is used to obtain the direction of the unit density gradient, and the orthogonal transformation is used to obtain the inclination direction of the boundary unit.

Number

[0015] In the formula, TIFF2025105594000003.tif76 is the inclination direction of the structural boundary between 0 and π, TIFF2025105594000004.tif89 is the gradient vector of the unit density, Different printing sub-areas correspond to the angle adjustment of different printing directions, which is represented by the real-time adjustment of the rotation of the biaxial positioner.

[0016] Preferably, a 6-axis industrial robot, a moving guide rail device, and a 2-axis positioner are used to form a 9-axis movement, and it is set to perform continuous linear interpolation and error compensation in a unified world coordinate system. The first axis of the moving guide rail device and the two axes of the 2-axis positioner are not interlocked. The path plan of the continuous linear interpolation includes a displacement plan and a speed plan. The displacement plan is executed by controlling the displacement change of each moving axis, and the trajectory is interpolated according to a plurality of continuous segments of polyline. For the coordinates (x i , y i , z i ) of each moving axis i (i = 1 to 9), the linear interpolation algorithm is as follows. x i = x1+(x2 - x1)×t y i = y1+(y2 - y1)×t z i = z1+(z2 - z1)×t

[0017] In the formula, (x1, y1, z1) is the starting point of the straight line, (x2, y2, z2) is the ending point of the straight line, t is the time parameter, and the range of its possible values is [0, 1]. In the process of controlling the movement of each moving axis, the movement error is calculated and judged point by point, compared with the planned path trajectory, and the next movement direction is determined based on the comparison result. The speed plan of the continuous linear interpolation is divided into the speed plan of the acceleration section and the speed plan of the constant speed section. The error compensation of the linear interpolation includes static error compensation and dynamic error compensation.

Advantages of the Invention

[0018] The beneficial effects are as follows: (1) The multi-axis 3D printing device and arc-based additive manufacturing method for metal structural parts provided by the present invention are based on the multi-axis linkage printing mode of the robot arm device, the moving guide rail device, and the positioner device. Through the expansion of the 6-axis robot arm, printing with a free posture of the robot arm becomes possible. By moving the guide rail, moving printing along the axis along the guide rail becomes possible, increasing the open movement space of the 3D printing robot. With a 2-axis positioner, multi-axis 3D printing without support for complex metal structural parts is realized, saving material costs and simplifying the post-processing process. At the same time, through the coordinated linear interpolation based on the world coordinate system, the printing accuracy and large size are effectively controlled, and further multi-axis 3D printing for large and complex metal structural parts is realized. (2) The present invention effectively overcomes the gravity overhang effect of multi-axis 3D printed metal structural parts through the external axis control mode of the rotation axis and the inversion axis of the 2-axis positioner. Through the program planning path, the two axes of the 2-axis positioner are controlled to rotate in real time. When printing parts of the structural parts, the printing angle of the parts is always above the critical printing angle, that is, in a printable state without support, realizing 3D printing without a support structure for the entire large and complex metal structural parts. (3) The present invention adopts an integrated integrated power supply device for additive manufacturing. The power supply device for additive manufacturing is installed on the support base plate together with the robot arm device and moves together in both directions along the track, effectively realizing automatic continuous stable wire supply. With the additive manufacturing monitoring device, the interlayer temperature measurement, the height measurement of the structural parts, the state of the molten pool, and the oxygen concentration in the atmosphere during the printing process are monitored in real time, making the operating state of the device stable and efficient.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying out the Invention

[0020] Hereinafter, the present invention will be further described with reference to examples. The description of the following examples is only for helping to understand the present invention. It should be explained that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications are also included in the protection scope of the claims of the present invention.

[0021] Example 1 As shown in FIGS. 1 to 7 in one embodiment, this multi-axis 3D printing device for metal structural parts includes a robot arm device, a moving guide rail device, an external motor device, a power source device for additive manufacturing, an integrated control device, a gun cleaning and wire cutting device, and an additive manufacturing monitoring device.

[0022] The robot arm device is composed of a 6-axis industrial robot 1 attached to a long guide rail assembly and a bottom base 3. The 6-axis industrial robot 1 has six servo axes and corresponds to two robot arm control methods: joint rotation and posture movement. As shown in FIGS. 1 and 4, the design parameters of the 6-axis industrial robot 1 include the maximum movement range, rated load, posture repeatability accuracy, number of axes, ambient temperature, and protection level. The 6-axis industrial robot 1 is fixed on the bottom base 3, and the bottom base 3 is fixed to the support base plate 4 via a connection flange. The movable base 2 is formed by the bottom base 3 and the support base plate 4. In this embodiment, the 6-axis industrial robot 1 has six controllable axes, a rated load of 70 kg, a maximum movement range of 2100 mm, and an ambient temperature of 0 to 55°C.

[0023] The moving guide rail device is a long guide rail assembly fixed to the ground. The movable base 2 is installed on the long guide rail assembly that can move freely, and the position of the 6-axis industrial robot 1 along the guide rail is controlled by a servo motor, expanding the 3D printing range. As shown in FIG. 5, the moving guide rail device is composed of a moving guide rail 5, a guide rail crawler 6, and a guide rail support 7. The guide rail support 7 is fixed to the ground via earth anchor bolts. The design parameters of the moving guide rail device include the movement stroke, repeat positioning accuracy, operating speed, reduction ratio, and rated output. The ultra-long moving guide rail is assembled by joining multiple sections. In this embodiment, the movement stroke of the moving guide rail device is 16 m, the reduction ratio is 1:10, and the running speed is 1 m / s.

[0024] The movable base 2 can move in two directions along the guide rail via a guide rail crawler 6 installed on the moving guide rail 5. The support base plate 4 adopts an integrated expansion structure, simultaneously supports the robot arm device and the power supply device for additive manufacturing, and moves synchronously with the guide rail. As shown in FIGS. 1 and 5, the transmission method of the moving guide rail device is rack and pinion transmission, and the operation is controlled by an external axis servo motor adapted to the robot arm device. The moving guide rail 5 and the rack protection adopt a semi-closed type, providing a certain degree of protection.

[0025] The external motor device includes an external axis motor 12 and is used for the two-axis drive control of the positioner device and the one-axis drive control of the moving guide rail device to realize the interlocking between the external axis motor 12 and the six-axis industrial robot 1.

[0026] The power supply device for additive manufacturing is an integrated device installed on the support base plate 4 and is composed of a CMT welder 15, a wire reel 16, a wire supply tube 18, a welding gun 19, an electric control box 27, and a cleaner 22. A shielding gas bottle 17 is further arranged on the side ground. The gas supply source is connected to the shielding gas bottle 17 through a long gas pipe. The cleaner 22 is arranged directly below the electric control box 27 and is composed of an intake arm, a motor, and an ash removal system.

[0027] The integrated control device includes an integrated control cabinet 13, a teaching pendant 20, and a visual operation console 28, and performs automatic control of the printing process. For safety reasons during the printing process, the integrated control device is arranged outside the arc prevention plate 26.

[0028] The gun cleaning and wire cutting device is composed of a wire cutting machine 21, and the wire cutting machine 21 is used for gun cleaning, wire cutting, and oil injection.

[0029] The additive manufacturing detection device includes an additive manufacturing online and offline monitoring system for detecting interlayer temperature, height of structural parts, state of the molten pool, and ambient oxygen concentration.

[0030] As shown in FIG. 1, the movement system design of the multi-axis 3D printing device is divided into the movement of the robotic arm, the movement of the long guide rail, and the movement of the positioner, with a total of 9 servo axes, and is divided into a 6-axis robotic arm assembly, a 1-axis long guide rail extension assembly, and a 2-axis positioner extension assembly. Interpolated linear interpolation was performed through the world coordinate system among the three assemblies.

[0031] The 6 axes of the robotic arm, the 1 axis of the long guide rail, and the 2 axes of the positioner constitute 9 moving axes, which are set in a unified world coordinate system, perform coordinated movement, and achieve unified interpolated linear interpolation and error compensation. Among them, the 1 axis of the long guide rail and the 2 axes of the positioner are set so that they cannot move simultaneously. The world coordinate system represents the actual moving coordinates of each moving axis i (i = 1 to 9) in the three-dimensional world as (x i , y i , z i ). The path plan of the interpolated linear interpolation includes a displacement plan and a speed plan. In the interpolated linear interpolation, a displacement plan is performed by controlling the displacement changes of each moving axis of the robotic arm, the long guide rail, and the positioner. As a result, the displacements of each moving axis approximate the actual ideal trajectory according to the interpolated trajectory in the form of a polyline of multiple continuous sections, realizing the 3D printing of metal structural parts. The linear interpolation algorithm for each moving axis i was as follows. x i = x1+(x2 - x1)×t y i = y1+(y2 - y1)×t z i = z1+(z2 - z1)×t

[0032] In the formula, (x1, y1, z1) is the starting point of the straight line, (x2, y2, z2) is the ending point of the straight line, t is the time parameter, and the range of possible values is [0, 1]. By controlling the change of the time parameter t, the linear interpolation movement of each moving axis i could be realized.

[0033] The principle of linear interpolation by the point-by-point comparison method is that in the process of controlling the movement of each moving axis, the computer calculates and identifies the movement error point by point, compares it with the planned path trajectory, and determines the next movement direction based on the comparison result. The speed plan of the coordinated linear interpolation is divided into an acceleration section and a constant-speed section. The goal was to improve the efficiency of 3D printing while considering the requirements of dynamic characteristics and movement accuracy.

[0034] The error compensation of linear interpolation includes static error compensation and dynamic error compensation. Static error compensation is realized by coordinate correction, etc. In dynamic error compensation, the trajectories of each axis are changed by methods such as acceleration prediction to eliminate errors during movement.

[0035] As shown in FIGS. 1 and 7, the power supply device for additive manufacturing is an integrated one-piece device, which is centrally arranged on the support base plate 4. Along with the movement of the moving guide rail, it moves in two directions along the guide rail synchronously with the 6-axis industrial robot 1. The power supply device for additive manufacturing is composed of a CMT welder 15, a wire reel 16, a wire supply tube 18, a welding gun 19, an electric control box 27, and a cleaner 22. The CMT welder 15 adopts the CMT cold metal transfer process. The welding wire melts to form droplets, which short-circuit between the droplets and the molten pool. When the droplets short-circuit, the output power of the digital power supply becomes almost zero. At the same time, the backward movement of the welding wire promotes the drop of the droplets and prevents the scattering of spatter.

[0036] As shown in FIGS. 1 and 7, the wire reel 16 is arranged on the CMT welding machine 15. Commonly used wires include stainless steel, carbon steel, aluminum alloy, titanium alloy, etc. The protective gas cylinder 17 is fixedly arranged on the ground on the side and is connected to a gas source containing gases such as argon, helium, and nitrogen through a long gas pipe. The CMT welding machine 15 is connected to the welding gun 19 through a wire supply tube 18. The welding gun 19 is fixed to the tip of the 6-axis industrial robot 1. The cleaner 22 is incorporated into the power supply device for additive manufacturing and is arranged directly below the electric control box 27. It moves along the track synchronously with the 6-axis industrial robot 1 and is used for purifying the fume and dust during the printing operation and the non-corrosive fume and dust gas containing no dried oil generated during welding. It is composed of an intake arm, a motor, and an ash removal system.

[0037] Example 2 As another example, based on Example 1, this Example 2 provides a multi-axis 3D printing device for more specific metal structural parts including a positioner device. The positioner device is a two-axis positioner 8 including a rotating shaft 9 with an infinite angle and a reversing shaft 10 with a limited angle.

[0038] As shown in FIGS. 1 and 6, the positioner device adopts the control mode of the two-axis positioner 8 including the rotating shaft 9 and the reversing shaft 10. The rotating shaft 9 can rotate infinitely in both directions around the central axis of the rotating disk 11, and the reversing shaft 10 can reverse in both directions around the horizontal axis. The maximum reversing angle is 120° or more. During multi-axis 3D printing, the structural part is arranged on the rotating disk 11, and the rotation speeds of the rotating shaft 9 and the reversing shaft 10 are 30° / second or more. In this example, the maximum reversing angle is ±135°.

[0039] As shown in FIG. 6, the setting of the positioner device is mainly used to overcome the gravity overhang effect when multi-axis 3D printing metal structural parts. Through the program planning path, the two axes of the positioner device are controlled to rotate in real time. When printing the parts of the structural parts, the printing angle of the parts is always above the critical printing angle, that is, in a printable state without support, realizing 3D printing without a support structure for the entire large and complex metal structural parts.

[0040] The process of the program planning path algorithm includes the division of the print sub-region, the local optimal printing direction, and the angle adjustment of the printing direction. The metal structural parts are divided into print sub-regions, and the local optimal printing direction θ for different sub-division regions i is calculated, and the overhang critical angle θ is set (for example: θ = 45°). When θ i ≥ θ, there is no gravity overhang effect, and it can be directly printed without the need to rotate the two axes of the positioner. When θ i < θ, there is an overhang effect due to gravity. By adjusting the two moving axes of the positioner, the local optimal printing direction of the adjusted structural parts meets the requirements, that is, θ i ’ ≥ θ, it can be printed. Generally, to ensure sufficient print quality, θ i ’ = 90° (vertical direction) can be adjusted. At the same time, it is necessary to consider the influence of the maximum print collision angle, realizing multi-axis 3D printing without a support structure.

[0041] The local optimal printing direction of each print sub-region is determined by the inclination direction of the boundary unit in the print sub-region. The boundary unit is a unit that includes empty cells in the adjacent set. The convolution kernel is used to obtain the direction of the density gradient of the unit, convert it to obtain the inclination direction of the boundary unit, and then determine the local optimal printing direction of each print sub-region considering the printability of the boundary unit of each print sub-region.

[0042] The unit density gradient direction is converted into the inclination direction of the structural boundary. The inclination direction of the structural boundary is the angle between the structural boundary and the X-axis, and the inclination direction of the structural boundary is orthogonal to the direction of the unit density gradient. For the unit density gradient directions in different quadrants, the corresponding inclination directions of the structural boundaries were as follows.

Number

[0043] In the formula, TIFF2025105594000006.tif76 is the inclination direction of the structural boundary between 0 and π, TIFF2025105594000007.tif89 was the gradient vector of the unit density.

[0044] Different printed sub-regions correspond to angle adjustments in different printing directions, which were represented by the real-time adjustment of the rotation of the two-axis positioner.

[0045] As shown in Fig. 1, both the moving guide rail device and the positioner device expand the number of printing axes of the robot arm device. As combination methods, they include the combination of the moving guide rail device and the robot arm device, and the combination of the positioner device and the robot arm device. The former is used for the 3D printing of long metal structural parts, and the latter is used for multi-axis 3D printing without support for independent complex metal structural parts or multi-axis 3D printing without local complex support for long metal structural parts.

[0046] As shown in Fig. 6, the positioner adopted a casting body to improve shock resistance, stability in high-temperature environments and long-term operations, reduce deformation, and a high-performance seal was installed at the reducer mounting part.

[0047] When performing multi-axis 3D printing without support for independent complex metal structural parts, or multi-axis 3D printing without local complex support for long metal structural parts, the structural parts are placed and realized on the rotating disk 11 of the positioner device. When performing 3D printing of long metal structural parts, the structural parts are placed and realized on the combined workbench 25, and the combined workbench 25 is formed by joining a plurality of independent mold workbenches. In this embodiment, the length of the moving guide rail was 16 m, and the length of the workbench was 15 m.

[0048] As shown in FIG. 1, the integrated control device is composed of an integrated control cabinet 13, a teaching pendant 20, and a visual operation console 28, and is arranged to automatically control the multi-axis movement of the robot arm device, the positioner device, and the moving guide rail device. The integrated control cabinet 13 has a maximum control axis number of 9 axes, including 6 axes of a 6-axis industrial robot, 2 axes of a positioner, and 1 axis of a moving guide rail. The teaching pendant 20 adopts a non-reflective touch screen mode, and the visual operation console 28 has a visual interface for visually controlling the printing and monitoring processes.

[0049] As shown in FIG. 1, the gun cleaning and wire cutting device is composed of a wire cutting machine 21. The wire cutting machine 21 is used for gun cleaning, wire cutting, and oil injection, is supported by a metal fixed bracket, and is arranged near the welding gun 19 when performing the printing operation. The wire cutting machine 21 is provided with a spatter prevention spray device 23 and a welding slag cleaning device 24. The spatter prevention spray device operates only by the movement of the robot, and the welding slag cleaning device 24 cleans the clamped and fixed welding gun 19 using a reamer.

[0050] In order to avoid visual impairment to surrounding workers due to the arc during printing, a movable arc prevention plate 26 is arranged around the multi-axis 3D printing device.

[0051] In addition, in this embodiment, for the same or similar parts as in Embodiment 1, reference can be made to each other and the description thereof is omitted.

[0052] Embodiment 3 As another embodiment, in this Embodiment 3, an arc-based additive manufacturing method for a multi-axis 3D printing device for metal structural parts based on Embodiments 1 and 2 is proposed. Based on the multi-axis linkage printing mode of the robot arm device, the moving guide rail device, and the positioner device, by expanding the 6-axis robot arm, printing with a free posture of the robot arm becomes possible. By moving the guide rail, a moving print following the axis along the guide rail is realized, and the open moving space of the 3D printing robot is expanded. With a 2-axis positioner, multi-axis 3D printing without support for complex metal structural parts is realized, saving material costs and simplifying the post-processing process. At the same time, through coordinated linear interpolation using the world coordinate system, the printing accuracy and large size are effectively controlled, and further multi-axis 3D printing for large and complex metal structural parts is realized. The specific printing method is shown in FIG. 8 and includes the following steps.

[0053] S1. A 3D model of a large and complex metal structural part was designed. S2. The 3D model was introduced into the slice path planning software according to a predetermined format, and a specific printing program was provided by the slice path planning software. S3. The printing program was introduced into the control software, and the slice path of the model was installed by the control software. S4. The printing execution unit of the multi-axis 3D printing device is divided into a robot arm device, a moving guide rail device, and a positioner device. The moving guide rail device and the positioner device are connected in parallel to the controller of the robot arm device. The multi-axis 3D printing device can print with a free posture of the robot arm and is in an interlocking mode following the axis along the guide rail in conjunction with the 2-axis movement of the positioner. By expanding the 3D printing range, multi-axis 3D printing for large and complex metal structural parts is realized, where "large" refers to the maximum size of metal structural parts of 1.0 m or more.

[0054] The external motor device is used for the two-axis drive control of the positioner device and the one-axis drive control of the moving guide rail device, belongs to the external axis motor 12, is installed on the side surfaces of the positioner device and the moving guide rail device respectively, the movement of the external axis motor 12 is integrally executed by the integrated control cabinet 13, and the movement control is combined with the internal axis motor 14 of the six-axis robot arm device to realize the interlocking between the external axis motor and the robot.

[0055] The execution logic of the multi-axis 3D printing device is the sequential additive manufacturing CAE system, the integrated control system, the equipment structure framework, and the print assembly. It operates the robot arm device, the moving guide rail device, and the positioner device to move cooperatively. The integrated control device adopts a multi-axis interlocking mode and is controlled via a bus. The integrated control device uses the industrial Internet bus to remotely collect the operation information of the equipment with high spatial and temporal resolutions, and based on this, provides high-level visualization and system decision-making. Through the external axis control mode of the infinite angle rotation axis and the limited angle inversion axis of the positioner device, the gravity overhang effect during the multi-axis 3D printing of metal structural parts is effectively overcome, and the two axes of the positioner device are controlled to rotate in real time through the program planning path.

[0056] S5. A practical 3D metal structure is constructed by melting a metal wire with the arc of a welding gun to realize multi-axis 3D printing. The integrated control of the robot arm device is used for 3D model data processing and the positioning movement of the robot arm. The 3D model data processing converts the 3D model file into a code file that can be directly read and executed by the robot. The specific method of the positioning movement of the robot arm is to identify the model, edit the code, and accurately control the positioning movement of the robot arm.

[0057] Through the integrated control of the moving guide rail device, the guide rail moves, and the robotic arm follows the direction of the guide rail and moves to the printing area. The integrated control of the positioner device is used for the two-axis movement control of the rotating disk 11, and by controlling the printing angle of the component, complex metal structural components can be printed without support. When printing the components of the structural parts, the printing angle of the components is always above the critical printing angle, that is, in a state where printing without support is possible, realizing 3D printing without a support structure for the entire large and complex metal structural parts.

[0058] The additive manufacturing monitoring device includes an additive manufacturing online monitoring system and an additive manufacturing offline monitoring system. During the printing process, it monitors the operating status of the device in real time. The monitoring content includes interlayer temperature measurement, height measurement of the structural parts, state of the molten pool, and oxygen concentration in the atmosphere. The interlayer temperature measurement is performed by a temperature measurement sensor, the height measurement of the structural parts is performed by a height measurement sensor, the state of the molten pool is performed by camera shooting, and the oxygen concentration in the atmosphere is performed by an atmospheric oxygen sensor.

[0059] This multi-axis 3D printing device and arc-based additive manufacturing method for metal structural parts can be applied to manufacturing large and long complex metal structural parts and structural systems with complex outer shapes and internal cavities using multi-axis 3D printing.

[0060] Each embodiment in this specification is described step by step. Each embodiment focuses on the differences from other embodiments, and the same and similar parts between each embodiment may be referred to each other.

Description of Reference Signs

[0061] 1 6-axis industrial robot 2 Movable base 3 Bottom base 4 Support base plate 5 Moving guide rail 6 Guide rail crawler 7 Guide rail support 8 2-axis positioner 9 Rotating shaft 10 Reversing shaft 11 Rotating disk 12 External shaft motor 13 Integrated control cabinet 14 Internal shaft motor 15 CMT welding machine 16 Wire reel 17 Shielding gas cylinder 18 Wire supply tube 19 Welding gun 20 Teaching pendant 21 Wire cutting machine 22 Purifier 23 Spatter prevention spray device 24 Welding slag cleaning device 25 Combination workbench 26 Arc prevention plate 27 Electric control box 28 Visual operation console

Claims

1. A multi-axis 3D printing device for metal structural parts, comprising a six-axis industrial robot, a bottom base, a power supply device for additive manufacturing, and a moving guide rail device. The bottom of the six-axis industrial robot is rotatably connected to the bottom base. The six-axis industrial robot and the bottom base form a robot arm device. The bottom of the power supply device for additive manufacturing and the bottom of the robot arm device are fixed to a support base plate. The support base plate moves along the length direction of the moving guide rail device. A welding gun is fixed to the tip of the six-axis industrial robot. The power supply device for additive manufacturing is connected to the welding gun via a wire supply tube. On one side of the moving guide rail device, a combined workbench is installed in combination with a two-axis positioner. The combined workbench is a long workbench parallel to the moving guide rail device. The two-axis positioner includes a rotating shaft and a reversing shaft. The rotation angle of the rotating shaft is an unlimited angle, and the reversing angle of the reversing shaft is a limited angle. A rotating disk is installed on the upper surface of the two-axis positioner. The metal structural part is placed on the combined workbench or the rotating disk. The moving guide rail device and the two-axis positioner are each characterized by controlling the driving of the corresponding first axis and second axis through an external axis motor. A multi-axis 3D printing device for metal structural parts.

2. The moving guide rail device includes a moving guide rail, a guide rail crawler, and a guide rail support. Both sides of the moving guide rail device are anchor-fixed to the ground via the guide rail support. The moving guide rail is installed along the entire length on both sides of the moving guide rail device. The guide rail crawler is connected to the support base plate, and the guide rail crawler is engaged and connected with the moving guide rail. The multi-axis 3D printing device for metal structural parts according to Claim 1.

3. The power supply device for additive manufacturing includes a CMT welder, a wire reel, a wire supply tube, a welding gun, an electric control box, and a cleaner. The welding gun is fixed to the tip of the six-axis industrial robot. The cleaner is arranged directly below the electric control box to form an integrated device. The bottoms of the electric control box, the cleaner, and the CMT welder are fixed to the support base plate. The wire reel is fixed to the CMT welder. The multi-axis 3D printing device for metal structural parts according to Claim 1.

4. On the ground outside the moving guide rail device, the integrated control cabinet, teaching pendant, visual operation console and wire cutting machine are installed, The multi-axis 3D printing apparatus for metal structural parts as described in claim 1, characterized in that the integrated control cabinet is arranged to control a total of nine-axis movement of the six-axis industrial robot, the moving guide rail device, and the two-axis positioner, the visual operation console is arranged to perform visual control and online monitoring of the printing process, and the wire cutting machine is equipped with an anti-spatter spray device and a welding slag cleaning device.

5. The multi-axis 3D printing apparatus for metal structural parts as described in claim 4, characterized in that: the two-axis positioner is located at the end of one side of the movable guide rail device, and an assembled worktable is installed on the same side within the length range of the corresponding movable guide rail device; a protective gas cylinder is installed on the ground on the other side of the movable guide rail device, and the protective gas cylinder supplies gas to the welding gun through a long gas pipe; the wire cutting machine and the purifier are arranged according to the position of the six-axis industrial robot; an arc prevention plate is surrounded around the multi-axis 3D printing apparatus for metal structural parts, and the integrated control cabinet, the teaching pendant and the visual operation console are arranged outside the arc prevention plate.

6. An arc-type additive manufacturing method for a multi-axis 3D printing device for metal structural parts according to any one of claims 1 to 5, comprising: A step S1 of designing a 3D model of a metal structural part; Step S2 of introducing the 3D model into slice path planning software and providing a specific print program through the slice path planning software; Step S3 of introducing a print program into the control software and installing a slice path of the model by the control software; Step S4: according to the characteristics of the metal structural parts, select printing with a two-axis positioner or printing with a combination worktable; if printing with a rotating disk is selected, the six-axis industrial robot, the moving guide rail device, and the two-axis positioner move in conjunction with each other; if printing with a combination worktable is selected, the six-axis industrial robot and the moving guide rail device move in conjunction with each other; A method for arc additive manufacturing of a multi-axis 3D printing apparatus for metal structural parts, comprising a step S5 of melting a metal wire with an arc of a welding gun and performing multi-axis 3D printing of the metal structural parts.

7. According to the program planned path, the integrated control cabinet controls the rotation of the two-axis positioner's rotation axis and reversal axis in real time, so that when printing any member of the structural part, the printing angle of the part is always above the critical printing angle, and the metal structural part on the rotating disk can overcome the gravity overhang effect. The arc additive manufacturing method of the multi-axis 3D printing apparatus for metal structural parts according to claim 6.

8. The process of the program planned path algorithm includes the division of the print sub-region, the calculation of the locally optimal print direction, and the angle adjustment of the print direction, as follows: Divide the structural parts into print sub-regions and calculate the local optimal print direction θ ｉ Set the overhang critical angle θ, and when θ ｉ ≥ θ, print directly. When θ ｉ < θ, the overhang effect due to gravity occurs. Adjust the two moving axes of the two-axis positioner so that the adjusted local optimal print direction θ ｉ '≥ θ, with θ ｉ ' = 90° as the vertical direction, realize multi-axis 3D printing without a support structure, The locally optimal print direction is determined by the inclination direction of the boundary unit in the print sub-region. The inclination direction of the structural boundary is the angle between the boundary and the X-axis. The direction of the unit density gradient is obtained using a convolution kernel, and the inclination direction of the boundary unit is obtained using an orthogonal transformation. 【Number 1】 Wherein, 【Number】 is the inclination direction of the structural boundary between 0 and π, 【Number】 is the gradient vector of the unit density, Different print sub-regions correspond to different angle adjustments of the print direction, which is represented by the real-time adjustment of the rotation of the two-axis positioner. The arc additive manufacturing method of the multi-axis 3D printing apparatus for metal structural parts according to claim 7.

9. A 6-axis industrial robot, a moving guide rail device, and a 2-axis positioner constitute 9-axis movement, and are set to perform continuous linear interpolation and error compensation in a unified world coordinate system. The 1-axis of the moving guide rail device and the 2 axes of the 2-axis positioner are not interlocked. The path plan of continuous linear interpolation includes a displacement plan and a speed plan. The displacement plan is executed by controlling the displacement change of each moving axis, and the trajectory is interpolated according to a plurality of continuous segments of polyline. For the coordinates (x ｉ , y ｉ , z ｉ ) of each moving axis i (i = 1 to 9), the linear interpolation algorithm is as follows: x ｉ = x １ + (x ２ - x １ ) × t y ｉ = y １ + (y ２ - y １ ) × t z ｉ = z １ + (z ２ - z １ ) × t where (x １ , y １ , z １ ) is the starting point of the straight line, (x ２ , y ２ , z ２ ) is the ending point of the straight line, t is a time parameter, and the range of values that t can take is [0, 1], In the process of controlling the movement of each moving axis, the movement error is calculated and determined point by point, compared with the planned path trajectory, and the next movement direction is determined based on the comparison result. The speed plan of the coordinated linear interpolation is divided into the speed plan of the acceleration section and the speed plan of the constant speed section. The error compensation of the linear interpolation includes static error compensation and dynamic error compensation. The arc additive manufacturing method of the multi-axis 3D printing apparatus for metal structural parts according to claim 8.

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