Multi-axis 3D printing equipment and arc-based additive manufacturing method for metal structural parts

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 in particular to a multi-axis 3D printing device and arc-based additive manufacturing method for metal structural parts. [Background technology]

[0002] Metal 3D printing, also known as metal additive manufacturing, offers advantages over traditional metal manufacturing processes, such as high efficiency and precision, making it suitable for the processing and production of complex metal structural parts. However, to ensure a successful print, metal structural parts must meet corresponding manufacturing constraints. Among these, the overhang effect caused by gravity is one of the major constraints in metal 3D printing. The overhang effect occurs when the angle between the structure boundary and the horizontal plane is smaller than a critical value, causing the metal material to collapse during the layer-by-layer deposition process due to the presence of gravity. This overhang effect can affect print quality and even result in the structural part failing to print.

[0003] From a structural design perspective, an effective way to overcome the overhang effect is to introduce angle constraints into the optimal design of the metal structure to obtain the optimal configuration that meets the angle manufacturing constraints. While conventional 3-axis robot metal 3D printing can obtain a self-supporting structure that meets the manufacturing constraints to avoid support waste, it often results in a significant increase in material consumption and a significant decrease in structural performance.

[0004] With the rapid development of the machinery industry, multi-axis 3D printing technology for metal structural parts has been widely used in fields such as aerospace and vehicle engineering. Multi-axis 3D printers for larger 3-axis metal structural parts feature a free-rotating base, which dynamically adjusts the printing direction during the printing process to avoid the overhang effect. This effectively solves the problem of increased volume and significantly reduced performance when 3-axis 3D printed self-supporting structures for metal structural parts are used. Therefore, the rational and effective design and construction of multi-axis robotic 3D printing equipment 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 research multi-axis 3D printing equipment and arc-type additive manufacturing methods for metal structural parts, adapt them to the additive manufacturing of complex and long metal structural parts, expand the size range of printed metal structural parts, save the printing costs of support structures, and recognize the need to print complex additive metal structural parts without supports. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to overcome the shortcomings of the prior art and provide a multi-axis 3D printing device and arc-based additive manufacturing method for metal structural parts. [Means for solving the problem]

[0007] This multi-axis 3D printing device for metal structural parts includes a six-axis industrial robot, a bottom base, an additive manufacturing power supply, 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 additive manufacturing power supply device 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 additive manufacturing power supply device is connected to the welding gun via a wire supply tube, A two-axis positioner and a combination worktable are installed on one side of the movable guide rail device. The combination worktable is a long worktable parallel to the movable guide rail device. The two-axis positioner includes a rotating axis and an inverting axis. The rotating axis has an unlimited rotation angle, but the inverting axis has a limited inverting angle. A rotating disk is installed on the upper surface of the two-axis positioner. Metal structural parts are placed on the combination worktable or the rotating disk. The movable guide rail device and the two-axis positioner respectively control the drive of the corresponding one axis and two axes through external axis motors.

[0008] Preferably, the movable guide rail device includes a movable guide rail, a guide rail crawler, and a guide rail support, both sides of the movable guide rail device are anchored to the ground via the guide rail supports, the movable guide rails are installed on both sides of the movable guide rail device over their entire length, the guide rail crawlers are connected to the support base plate, and the guide rail crawlers are meshed and connected to the movable guide rail.

[0009] Preferably, the additive manufacturing power supply includes a CMT welding machine, a wire reel, a wire supply tube, a welding gun, an electrical control box, and a purifier, wherein the welding gun is fixed to the tip of a six-axis industrial robot, the purifier is located directly below the electrical control box to form an integrated device, and the electrical control box, the purifier, and the bottom of the CMT welding machine are fixed to a 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, and the wire cutting machine is installed with an anti-spatter 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, and a combination workbench 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 purifier are arranged in accordance with the position of the six-axis industrial robot, and an arc prevention plate is surrounded around the multi-axis 3D printing device for metal structural parts, and the integrated control cabinet, teaching pendant, and visual operation console are arranged outside the arc prevention plate.

[0012] The arc-type additive manufacturing method for such a multi-axis 3D printing machine for metal structural parts is Step S1 of designing a 3D model of a metal structural part; Step S2: when the 3D model is introduced into the slice path planning software, a specific print program is provided by the slice path planning software; Step S3: introducing a print program into the control software and installing a slice path for the model through the control software; Step S4: according to the characteristics of the metal structural part, 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; Step S5 includes 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 above 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 dividing the printing area, calculating the local optimal printing direction, and adjusting the angle of the printing direction, and is as follows: Divide the structural part into print areas and determine the optimal local print direction θ i Calculate the overhang critical angle θ and set θ i If ≥ θ, print directly, and i When <θ, the gravity overhang effect occurs, and the two moving axes of the two-axis positioner are adjusted to find the local optimal printing direction θ. i ' ≥ θ, and θ i '=90° is the vertical direction, realizing multi-axis 3D printing without support structures, The local optimal printing direction was determined by the gradient direction of the boundary units within the printing subregion. The gradient direction of the structure boundary was the angle between the boundary and the X-axis. A convolution kernel was used to obtain the direction of the density gradient of the unit, and an orthogonal transformation was used to obtain the gradient direction of the boundary units.

number

[0015] During the ceremony, TIFF0007827380000002.tif76 is the dip direction of the structure boundary between 0 and π, TIFF0007827380000003.tif89 is the gradient vector of unit density, Different print sub-areas correspond to different print orientation angle adjustments, which are represented by real-time adjustments of the rotation of the two-axis positioner.

[0016] Preferably, a 6-axis industrial robot, a mobile guide rail device, and a 2-axis positioner are used to form a 9-axis movement, and the robot is configured to perform linked linear interpolation and error compensation in a unified world coordinate system. One axis of the mobile guide rail device and two axes of the 2-axis positioner are not linked. The path planning for the linked linear interpolation includes displacement planning and speed planning. Displacement planning is performed by controlling the displacement changes of each moving axis. The trajectory is interpolated according to a continuous multi-segment polyline, and the coordinates (x, y, z) of each moving axis i (i=1 to 9) are calculated. i , y i , z i ) the linear interpolation algorithm was as follows: x i =x1+(x2-x1)×t y i =y1+(y2-y1)×t z i =z1+(z2-z1)×t

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

[0018] The beneficial effects are: (1) The multi-axis 3D printing device and arc-type additive manufacturing method for metal structural parts provided by the present invention is based on the multi-axis linked printing mode of a robot arm device, a movable guide rail device, and a positioner device. The expansion of the 6-axis robot arm enables the robot arm to print in any position. The moving guide rail enables moving printing along the guide rail, which increases the open movement space of the 3D printing robot. The 2-axis positioner enables support-free multi-axis 3D printing of complex metal structural parts, saving material costs and simplifying post-processing processes. At the same time, linked linear interpolation based on the world coordinate system effectively controls printing accuracy and large size, realizing multi-axis 3D printing of even larger and more complex metal structural parts. (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 two-axis positioner. Through the program planning path, the two axes of the two-axis positioner are controlled to rotate in real time. When printing the structural parts, the printing angle of the parts is always above the critical printing angle, that is, it is in a state where it can be printed without support, and realizes 3D printing without support structures for the entire large and complex metal structural parts. (3) The present invention adopts an integrated, all-in-one additive manufacturing power supply device. The additive manufacturing power supply device 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, and stable wire supply. The additive manufacturing monitoring device monitors the interlayer temperature measurement, structural part height measurement, molten pool status, and atmospheric oxygen concentration during the printing process in real time, making the device's operating status stable and efficient. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an overall schematic diagram of a multi-axis robotic 3D printing device for metal structural parts. [Figure 2] 2 is an overall schematic diagram of a multi-axis robotic 3D printing device for metal structural parts. [Figure 3]FIG. 1 is a top view schematic of a multi-axis robotic 3D printing device. [Figure 4] This is a schematic diagram of the workspace of a six-axis industrial robot. [Figure 5] FIG. 2 is a schematic structural diagram of a moving guide rail device. [Figure 6] FIG. 1 is a schematic structural diagram of a two-axis positioner device. [Figure 7] Schematic diagram of the structure of a power supply and wire reel for CMT additive manufacturing. [Figure 8] 1 is a flowchart of an arc-based additive manufacturing method for a multi-axis 3D printing device for metal structural parts. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described below with reference to examples. The following examples are only intended to help understand the present invention. It should be noted that those skilled in the art can make some modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications are also included in the scope of protection of the claims of the present invention.

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

[0022] The robot arm device comprises a six-axis industrial robot 1 mounted on a long guide rail assembly and a base 3. The six-axis industrial robot 1 has six servo axes and supports two robot arm control methods: joint rotation and posture translation. As shown in Figures 1 and 4, the design parameters of the six-axis industrial robot 1 include maximum travel range, rated load, posture repeatability, number of axes, ambient temperature, and protection level. The six-axis industrial robot 1 is fixed on top of the base 3, which is fixed to a support base plate 4 via a connecting flange. The base 3 and support base plate 4 form a movable base 2. In this example, the six-axis industrial robot 1 has six controllable axes, a rated load of 70 kg, a maximum travel range of 2100 mm, and an ambient temperature range of 0 to 55°C.

[0023] The mobile guide rail device is a long guide rail assembly fixed to the ground. A movable base 2 is mounted on the long, movable guide rail assembly. A servo motor controls the position of the six-axis industrial robot 1 along the guide rail, expanding the 3D printing range. As shown in FIG. 5, the mobile guide rail device is composed of a mobile guide rail 5, a guide rail crawler 6, and a guide rail support 7. The guide rail support 7 is fixed to the ground with ground anchor bolts. The design parameters of the mobile guide rail device include the travel stroke, repeatable positioning accuracy, operating speed, reduction ratio, and rated power. The ultra-long mobile guide rail is assembled by joining multiple sections. In this embodiment, the mobile guide rail device has a travel stroke of 16 m, a reduction ratio of 1:10, and a running speed of 1 m / s.

[0024] The movable base 2 can move in two directions along the guide rail via guide rail crawlers 6 installed on the movable guide rail 5, and the support base plate 4 adopts an integrated extension structure to simultaneously support the robot arm device and the additive manufacturing power supply device and move synchronously with the guide rail. As shown in Figures 1 and 5, the transmission method of the movable guide rail device is rack and pinion transmission, and its operation is controlled by an external axis servo motor matched to the robot arm device, and the movable guide rail 5 and rack protection are semi-enclosed, providing a certain degree of protection.

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

[0026] The additive manufacturing power supply unit is an integrated, all-in-one unit, installed on a support base plate 4, and consisting of a CMT welding machine 15, a wire reel 16, a wire supply tube 18, a welding gun 19, an electrical control box 27, and a purifier 22. A protective gas bottle 17 is further installed on the side ground, and the gas supply source is connected to the protective gas bottle 17 via a long gas pipe. The purifier 22 is installed directly below the electrical control box 27, and consists 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 located outside the arc prevention plate 26.

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

[0029] The additive manufacturing detection equipment includes an additive manufacturing online and offline monitoring system that detects interlayer temperature, structural part height, melt pool condition, and atmospheric oxygen concentration.

[0030] As shown in Figure 1, the movement system design of the multi-axis 3D printing device is divided into robot arm movement, long guide rail movement, and positioner movement, with a total of nine servo axes. It is divided into a six-axis robot arm assembly, a one-axis long guide rail extension assembly, and a two-axis positioner extension assembly, and linked linear interpolation is performed between the three assemblies through the world coordinate system.

[0031] The six axes of the robot arm, one axis of the long guide rail, and two axes of the positioner make up nine moving axes, which are set in a unified world coordinate system and perform linked movement, realizing unified linked linear interpolation and error compensation. Among these, the one axis of the long guide rail and the two axes of the positioner are set so that they cannot move simultaneously. The world coordinate system defines the actual moving coordinates of each moving axis i (i=1~9) in the 3D world as (x i ,y i ,z i ) and the path planning of linked linear interpolation includes displacement planning and velocity planning, In the linked linear interpolation, displacement planning is performed by controlling the displacement changes of each moving axis of the robot arm, long guide rail, and positioner. This allows the displacement of each moving axis to approximate the actual ideal trajectory according to the interpolated trajectory in the form of a continuous multi-section polyline, thereby realizing 3D printing of metal structural parts. The linear interpolation algorithm for each moving axis i is 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 start point of the line, (x2, y2, z2) is the end point of the line, t is the time parameter whose possible value range is [0, 1], and by controlling the change in the time parameter t, linear interpolation movement of each movement axis i can be realized.

[0033] The principle of point-by-point linear interpolation 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 linked linear interpolation is divided into an acceleration section and a constant speed section, and the goal is to improve the efficiency of 3D printing while taking into account the requirements of dynamic characteristics and movement accuracy.

[0034] Linear interpolation error compensation includes static error compensation and dynamic error compensation. Static error compensation is achieved by coordinate correction, etc., while dynamic error compensation changes the trajectory of each axis using methods such as acceleration prediction to eliminate errors during movement.

[0035] As shown in Figures 1 and 7, the additive manufacturing power supply device is an integrated, all-in-one device that is centrally arranged on a support base plate 4. It moves in two directions along the guide rail in synchronization with the six-axis industrial robot 1 as the guide rail moves. The additive manufacturing power supply device is composed of a CMT welding machine 15, a wire reel 16, a wire supply tube 18, a welding gun 19, an electrical control box 27, and a purifier 22. The CMT welding machine 15 uses the CMT cold metal transfer process, in which the welding wire melts to form droplets, which then short-circuit between the droplets and the molten pool. When the droplets short-circuit, the output power of the digital power supply drops to almost zero. At the same time, the retreating movement of the welding wire promotes the drop of the droplets and prevents splashing.

[0036] As shown in Figures 1 and 7, a wire reel 16 is placed on top of the CMT welding machine 15. Commonly used wires include stainless steel, carbon steel, aluminum alloy, and titanium alloy. A protective gas cylinder 17 is fixed to the ground on the side and connected to a gas supply source, such as argon, helium, or nitrogen, via a long gas pipe. The CMT welding machine 15 is connected to a welding gun 19 via a wire supply tube 18. The welding gun 19 is fixed to the end of the six-axis industrial robot 1. A purifier 22, built into the additive manufacturing power supply unit, is located directly below the electrical control box 27 and moves along a track in synchronization with the six-axis industrial robot 1. It is used to purify exhaust smoke and dust during printing operations and to purify dry, oil-free, non-corrosive exhaust smoke and dust gases generated during welding. It consists of an intake arm, motor, and ash removal system.

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

[0038] As shown in Figures 1 and 6, the positioner device adopts a control mode of a two-axis positioner 8 including a rotation axis 9 and a reversal axis 10. The rotation axis 9 can rotate in both directions at an infinite angle around the central axis of the rotating disk 11, and the reversal axis 10 can reversibly rotate around a horizontal axis with a maximum reversal angle of 120° or more. During multi-axis 3D printing, the structural part is placed on the rotating disk 11, and the rotation speed of the rotation axis 9 and the reversal axis 10 is 30° / sec or more. In this embodiment, the maximum reversal angle is ±135°.

[0039] As shown in Figure 6, the positioner device settings are 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 a structural part, the printing angle of the part is always above the critical printing angle, that is, it is in a state where it can be printed without support, and support structure-free 3D printing of the entire large and complex metal structural part is realized.

[0040] The process of the program planning path algorithm includes dividing the printing sub-area, locally optimal printing direction, and adjusting the angle of the printing direction. The metal structural part is divided into printing sub-areas, and the locally optimal printing direction θ for different sub-division areas is calculated. i Calculate the critical overhang angle θ and set it (e.g. θ = 45°). i If θ≧θ, there is no gravity overhang effect, so printing can be done directly without rotating the two axes of the positioner. i When <θ, there is an overhang effect due to gravity, and the two movement axes of the positioner are adjusted to ensure that the local optimal printing direction of the adjusted structural part meets the requirements, that is, θ i ' ≥ θ, printing is possible, and generally, to ensure sufficient print quality, θ i '=90° (vertical direction) can be adjusted, and at the same time, the effect of the maximum print impact angle must be taken into consideration, realizing multi-axis 3D printing without support structures.

[0041] The local optimal print direction of each print sub-region was determined by the gradient direction of the boundary units within the print sub-region, where the boundary units are units containing empty cells in an adjacent set. A convolution kernel was used to obtain the density gradient direction of the unit and transformed to obtain the gradient direction of the boundary units. Then, the local optimal print direction of each print sub-region was determined by considering the printability of the boundary units of each print sub-region.

[0042] The unit density gradient direction was converted to the slope direction of the structure boundary, which was the angle between the structure boundary and the X axis, and the slope direction of the structure boundary was perpendicular to the direction of the unit density gradient. For unit density gradient directions in different quadrants, the corresponding slope directions of the structure boundary were as follows:

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[0043] During the ceremony, TIFF0007827380000005.tif76 is the dip direction of the structure boundary between 0 and π, TIFF0007827380000006.tif89 was a unit density gradient vector.

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

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

[0046] As shown in Figure 6, the positioner uses a cast body to improve impact resistance, stability in high-temperature environments and long-term operation, and reduce deformation, and a high-performance seal is installed in the reducer mounting area.

[0047] When performing support-free multi-axis 3D printing of independent complex metal structural parts, or localized complex support-free multi-axis 3D printing of long metal structural parts, the structural parts are placed on the rotating disk 11 of the positioner device, and when performing 3D printing of long metal structural parts, the structural parts are placed on the assembly worktable 25, which is formed by joining multiple independent mold worktables. In this example, the length of the moving guide rail was 16 m, and the length of the worktable was 15 m.

[0048] As shown in Figure 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 configured to automatically control the multi-axis movement of the robot arm device, positioner device, and moving guide rail device. The integrated control cabinet 13 can control a maximum of nine axes, including six axes for the six-axis industrial robot, two axes for the positioner, and one axis for the moving guide rail. The teaching pendant 20 uses a non-reflective touchscreen, and the visual operation console 28 has a visual interface for visually controlling the printing and monitoring process.

[0049] As shown in FIG. 1, the gun cleaning and wire cutting device comprises a wire cutting machine 21, which is used for gun cleaning, wire cutting, and oil injection. The wire cutting machine 21 is supported by a metal fixing bracket and is positioned near the welding gun 19 when performing a printing operation. The wire cutting machine 21 is equipped with an anti-spatter spray device 23 and a welding slag cleaning device 24. The anti-spatter spray device is operated only by the movement of the robot, and the welding slag cleaning device 24 cleans the clamped welding gun 19 using a reamer.

[0050] To prevent arcs from damaging the vision of nearby workers during printing, a movable arc prevention plate 26 was placed around the multi-axis 3D printing device.

[0051] In this embodiment, parts that are the same as or similar to those in the first embodiment can be referred to, and the description thereof will be omitted.

[0052] Example 3 As another example, Example 3 proposes an arc-type additive manufacturing method for a multi-axis 3D printing machine for metal structural parts based on Examples 1 and 2. Based on the multi-axis linked printing mode of the robot arm device, moving guide rail device, and positioner device, the expansion of the six-axis robot arm allows the robot arm to print in any position. By moving the guide rail, moving printing along the guide rail is realized, expanding the open movement space of the 3D printing robot. A two-axis positioner enables support-free multi-axis 3D printing of complex metal structural parts, saving material costs and simplifying post-processing. At the same time, linked linear interpolation using the world coordinate system effectively controls printing accuracy and large size, enabling multi-axis 3D printing for even larger and more complex metal structural parts. The specific printing method is shown in Figure 8 and includes the following steps:

[0053] S1 designed a 3D model of a large, complex metal structural part. S2, the 3D model was introduced into the slice path planning software according to the prescribed format, and a specific print program was provided from the slice path planning software. S3, the print program was introduced into the control software, and the slice path of the model was installed by the control software. The print execution unit of the S4 multi-axis 3D printing device is divided into a robot arm device, a movable guide rail device, and a positioner device, with the movable guide rail device and positioner device connected in parallel to the robot arm device's controller. The multi-axis 3D printing device allows the robot arm to print in any position, and is in a linked mode along the axes along the guide rail in conjunction with the two-axis movement of the positioner. The expansion of the 3D printing range has made multi-axis 3D printing possible for large, complex metal structural parts, where large refers to a maximum size of metal structural parts of 1.0m or more.

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

[0055] The execution logic of the multi-axis 3D printing equipment is a sequential additive manufacturing CAE system, integrated control system, equipment structural framework, and printing assembly, which operates the robotic arm device, moving guide rail device, and positioner device to move in a coordinated manner. The integrated control device adopts a multi-axis linkage mode and is controlled via a bus. The integrated control device uses an industrial Internet bus to remotely collect equipment operating information with high spatial and temporal resolution, and based on this, provides high-level visualization and system decision-making. The external axis control mode of the positioner device's infinite-angle rotation axis and limited-angle inversion axis effectively overcomes the gravitational overhang effect when multi-axis 3D printing metal structural parts. The two axes of the positioner device are controlled to rotate in real time through a program planning path.

[0056] S5: Using the arc of a welding gun to melt metal wire, a real 3D metal structure is constructed, achieving multi-axis 3D printing. The integrated control of the robot arm device is used for 3D model data processing and robot arm positioning and movement. 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 for positioning and movement of the robot arm is to identify the model and edit the code to accurately control the positioning and movement of the robot arm.

[0057] The guide rail is moved by the integrated control of the moving guide rail device, and the robot arm moves to the printing area following the direction of the guide rail. The integrated control of the positioner device is used to control the two-axis movement of the rotating disk 11. By controlling the printing angle of the part, complex metal structural parts can be printed without supports. When printing structural parts, the printing angle of the part is always above the critical printing angle, that is, it is possible to print without supports, thereby realizing 3D printing of large and complex metal structural parts without support structures.

[0058] The additive manufacturing monitoring device includes an additive manufacturing online monitoring system and an additive manufacturing offline monitoring system, which monitors the operating status of the device in real time during the printing process. The monitored contents include interlayer temperature measurement, structural part height measurement, molten pool status, and atmospheric oxygen concentration, where interlayer temperature measurement is performed using a temperature measurement sensor, structural part height measurement is performed using a height measurement sensor, molten pool status is measured using a camera, and atmospheric oxygen concentration is measured using an atmospheric oxygen sensor.

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

[0060] Each embodiment in this specification is described step by step, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments may be cross-referenced. [Explanation of symbols]

[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 Rotation Axis 10 Inverted Axis 11 Rotating disc 12 External shaft motor 13 Integrated Control Cabinet 14 Internal shaft motor 15 CMT welding machine 16 Wire reel 17 Protective gas cylinder 18 Wire feed tube 19 Welding gun 20 Teaching Pendant 21 Wire cutting machine 22 Purifier 23 Anti-spatter spray device 24 Welding slag cleaning equipment 25 Combination Workbench 26 Arc prevention plate 27 Electrical 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, an additive manufacturing power supply device, and a moving guide rail device, wherein 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 additive manufacturing power supply device 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 additive manufacturing power supply device is connected to the welding gun via a wire supply tube; a two-axis positioner and an assembly worktable are installed on one side of the movable guide rail device, the assembly worktable is a long-shaped worktable parallel to the movable guide rail device, the two-axis positioner includes a rotation axis and an inversion axis, the rotation axis has an unlimited rotation angle and the inversion axis has a limited inversion angle, a rotating disk is installed on the upper surface of the two-axis positioner, the metal structural part is placed on the assembly worktable or the rotating disk, and the movable guide rail device and the two-axis positioner respectively control the drive of the corresponding one axis and two axes through external axis motors.

2. The multi-axis 3D printing apparatus for metal structural parts according to claim 1, characterized in that the movable guide rail device includes a movable guide rail, a guide rail crawler, and a guide rail support, both sides of the movable guide rail device are anchored to the ground via the guide rail support, the movable guide rail is installed on both sides of the movable guide rail device over its entire length, the guide rail crawler is connected to the support base plate, and the guide rail crawler is meshed and connected to the movable guide rail.

3. 2. The multi-axis 3D printing apparatus for metal structural parts of claim 1, wherein the additive manufacturing power supply equipment includes a CMT welding machine, a wire reel, a wire supply tube, a welding gun, an electric control box, and a purifier, wherein the welding gun is fixed to the tip of a six-axis industrial robot, and the purifier is disposed directly below the electric control box to form an integrated device, and the bottom of the electric control box, the purifier, and the CMT welding machine are fixed to a supporting base plate, and the wire reel is fixed to the CMT welding machine.

4. On the ground outside the moving guide rail device, an integrated control cabinet, a teaching pendant, a visual operation console and a 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 configured to control the movement of a total of nine axes, including the six-axis industrial robot, the moving guide rail device, and the two-axis positioner, the visual operation console is configured 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. 5. The multi-axis 3D printing apparatus for metal structural parts according to claim 4, wherein the two-axis positioner is located at one end of the movable guide rail device, and an assembly 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 cutter and purifier are arranged in accordance with 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, teaching pendant, and 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: Step S1 of designing a 3D model of a metal structural part; Step S2: introducing the 3D model into slice path planning software and providing a specific print program through the slice path planning software; Step S3: introducing a print program into the control software and installing a slice path for the model through 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 work table; 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 work table is selected, the six-axis industrial robot and the moving guide rail device move in conjunction with each other; and step S5 of melting a metal wire with an arc from a welding gun and performing multi-axis 3D printing of the metal structural part.

7. The arc-type additive manufacturing method of the multi-axis 3D printing device for metal structural parts, as described in claim 6, characterized in that the integrated control cabinet controls the rotation of the rotation axis and the inversion 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.

8. The process of the program planning path algorithm includes dividing the printing sub-area, calculating the local optimal printing direction and adjusting the angle of the printing direction, which is as follows: Divide the structural part into print sub-regions and find the optimal local print direction θ ｉ Calculate the overhang critical angle θ and set θ ｉ If ≥ θ, print directly, and ｉ < θ, the overhang effect due to gravity occurs, and the two moving axes of the two-axis positioner are adjusted to find the locally optimal printing direction θ ｉ ' ≥ θ, and θ ｉ '=90° is the vertical direction, realizing multi-axis 3D printing without support structures. The local optimal printing direction is determined by the inclination direction of the boundary unit in the printing sub-region, and the inclination direction of the structure boundary is the angle between the boundary and the X-axis. A convolution kernel is used to obtain the direction of the density gradient of the unit, and an orthogonal transformation is used to obtain the inclination direction of the boundary unit; [Equation 1] During the ceremony, 【number】 is the dip direction of the structure boundary between 0 and π, 【number】 is the gradient vector of unit density, The arc-type additive manufacturing method of a multi-axis 3D printing device for metal structural parts described in claim 7, characterized in that different printing sub-areas correspond to different angular adjustments of printing directions, which are represented by real-time adjustments of the rotation of the two-axis positioner.

9. A 6-axis industrial robot, a mobile guide rail device, and a 2-axis positioner are used to form a 9-axis movement, which is configured to perform linked linear interpolation and error compensation in a unified world coordinate system. One axis of the mobile guide rail device and two axes of the 2-axis positioner are not linked. The path planning for the linked linear interpolation includes displacement planning and speed planning. Displacement planning is performed by controlling the displacement changes of each moving axis, and the trajectory is interpolated according to a continuous multi-segment polyline. The coordinates (x ｉ , y ｉ , z ｉ ) 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 In the formula, (x １ , y １ , z １ ) is the starting point of the line, and (x ２ , y ２ , z ２ ) is the end point of the line, t is a time parameter, and the range of possible values ​​of t is [0, 1], In the process of controlling the movement of each moving axis, the movement error is calculated and judged for each point, and compared with the planned path trajectory, and the next movement direction is determined based on the comparison result; The speed plan for linked linear interpolation is divided into the speed plan for the acceleration section and the speed plan for the constant speed section. The arc-type additive manufacturing method of a multi-axis 3D printing device for metal structural parts according to claim 8, wherein the error compensation of linear interpolation includes static error compensation and dynamic error compensation.

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