A 3D printing test device and test method for teaching based on a parallel manipulator

Abstract

The present application relates to the technical field of device performance test, and more particularly to a 3D printing test device for teaching based on parallel manipulator and a test method thereof, which comprises a supporting mechanism, a parallel manipulator motion mechanism, a wire feeding mechanism, a printing head and a performance test module, and can meet the needs of printing test of different shapes of printing test pieces. Through the setting of the performance test module, the elastic deformation of the corresponding components of the manipulator motion mechanism and the thermal deformation of the printing head can be obtained. Through the independently set height camera, the actual position of the printing head of the 3D printing test device in the printing process can be obtained, and the motion error of the printing head can be further obtained. Through multiple tests and in combination with data processing methods such as regression analysis, the precision retention of the 3D printing test device under different printing conditions can be obtained. The present application can also be combined with the popular science education of teenagers for 3D printing, and become a test device integrating popular science education of teenagers and 3D printing performance test.

Description

Technical Field

[0001] This invention relates to the technical field of performance testing and demonstration devices for popular science education, and in particular to a teaching 3D printing experimental device and experimental method based on a parallel robotic arm. Background Technology

[0002] 3D printing is an additive manufacturing method that shapes materials through material deposition. Compared with traditional subtractive manufacturing processes such as turning, milling, and drilling, 3D printing overcomes the disadvantages of traditional manufacturing processes, such as numerous steps, molds, long processing cycles, and high costs for small-batch production, due to its top-down material stacking method. It also offers significant advantages in model iteration, optimization, and improvement. 3D printing technology has been applied in high-end manufacturing fields such as aerospace, new energy vehicles, and petrochemicals, leading the technological forefront of the nation's core equipment manufacturing development.

[0003] 3D printers are core equipment in additive manufacturing. The motion error of their printhead and its accuracy retention are affected by printing speed and the motion accuracy of the mechanism, directly impacting the surface morphology (e.g., roughness) and mechanical properties (e.g., structural stiffness, yield strength) of the 3D printed workpiece. Taking a 3D printing mechanism based on a parallel manipulator as an example, in the actual printing process, the printhead is fixed on a parallel manipulator platform. A servo motor drives the manipulator platform to stack material on the workpiece surface according to a predetermined trajectory to complete the printing process. However, the motion accuracy of the parallel mechanism driving the printhead is affected by factors such as the stiffness of the crank and connecting rod and the thermal deformation of the printhead's metal components, resulting in motion errors between the actual output trajectory of the printhead and the theoretical design value. Furthermore, the manipulator's motion accuracy indicators exhibit a gradual change in system accuracy retention over time under the influence of factors such as different forward and reverse rotation frequencies of the servo motor, crank and connecting rod speeds, and the number of reciprocating cycles of the joint rotation pairs. Therefore, designing an experimental testing device that can reflect the influence of factors such as crank connecting rod elastic deformation, print head thermal deformation, and motor drive frequency on the quality of 3D printed workpieces is of great significance for improving the control accuracy of 3D printing robots and enhancing the surface processing and mechanical properties of workpieces.

[0004] 3D printing, as a key technology in additive manufacturing, is integrated with robotics, drone technology, and computer programming, forming the core content of current science education focused on artificial intelligence and intelligent manufacturing. Practical operation is an important means to deepen understanding of 3D printing technology based on lectures on principles and observation of production processes. Combining 3D printing experimental testing devices and data analysis methods, exploring the influence of factors such as motor drive speed, elastic deformation of kinematic pairs, and thermal deformation of the print head on the surface quality and mechanical properties of the formed products requires a 3D printing experimental testing device and method for youth science education based on a parallel robotic arm.

[0005] Furthermore, acquiring and evaluating the impact of the printing mechanism's motion accuracy and component thermal deformation on the quality of 3D printed products requires conducting tests and assessments of workpiece surface morphology and sample mechanical properties under different motion accuracy and printhead operating temperatures. Typically, testing the printhead's motion accuracy and its retention characteristics under actual operating conditions requires long-term accumulation of workpiece surface morphology data, consuming significant human, material, and financial resources. Therefore, this invention combines immersive 3D printing science education with experimental testing of factors affecting the device's operational accuracy and retention. By adjusting the printing mechanism's operating parameters through a drive motor, and combining tests of the motion mechanism's elastic deformation, servo motor drive torque measurement, and printhead thermal deformation detection, it simulates the impact of different printing speeds and operating temperatures on the system's motion accuracy and retention. This is of great significance for enabling young people to gain a deeper understanding of 3D printing mechanism performance parameters, improving 3D printing mechanism design and evaluation standards, and improving and developing new 3D printer mechanical structures. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a teaching 3D printing experimental device and method based on a parallel manipulator. It solves the technical problem that, due to the motion error between the actual output trajectory of the print head and the design theoretical value, it is necessary to test the influence of factors such as the elastic deformation of the crank connecting rod, the thermal deformation of the print head, and the motor drive frequency on the quality of 3D printed workpieces. It guides teenagers to understand the key factors affecting the quality of 3D printed products.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0010] A teaching 3D printing experimental device based on parallel manipulators includes: a support mechanism, several parallel manipulator motion mechanisms, a filament feeding mechanism, a print head, and a performance testing module.

[0011] Several robotic arm motion mechanisms are arranged on the top of the support mechanism, and the lower end of the robotic arm motion mechanism is connected to the print head. The robotic arm motion mechanism drives the print head to perform 3D printing through a servo motor.

[0012] The filament feeding mechanism is mounted on the support mechanism and is used to feed a material rod for 3D printing to the print head.

[0013] The performance testing module includes: several strain sensors and a high-speed camera. The strain sensors are set at the strain measurement points of the 3D printing test device to obtain the elastic deformation parameters of the robotic arm motion mechanism and the thermal deformation parameters of the print head. The high-speed camera is set independently of the support mechanism and is used to obtain the actual position of the print head during the printing process.

[0014] The support structure includes: an aluminum profile frame, a support platform, a heated bed, and a static platform;

[0015] The static platform is located on the upper part of the aluminum profile frame, the support platform is located on the lower part of the aluminum profile frame, and the heated bed is located on top of the support platform. The height of the heated bed is adjustable.

[0016] Several robotic arm motion mechanisms are arranged around the static platform, and the robotic arm motion mechanisms further include: cranks and connecting rods;

[0017] One end of the crank is rotatably connected to the output end of the servo motor via a coupling, and the crank is set perpendicular to the output end of the servo motor;

[0018] The bottom of the connecting coupling is provided with a fixing seat, through which the coupling and the servo motor are fixed on a stationary platform;

[0019] The crank is provided with a pair of drive arm fixing posts at the end away from the coupling. The outer end of the drive arm fixing post is provided with a ball joint. The connecting rod is rotatably connected to the crank through the ball joint.

[0020] The lower end of the connecting rod of all the aforementioned robotic arm motion mechanisms is also connected to a movable platform. The movable platform is rotatably connected to the connecting rod via a movable platform connecting column, and the movable platform is used to mount the print head.

[0021] The printhead is fixed to the moving platform by hex bolts and nuts, and the printhead includes: a printhead nozzle cover and a printhead nozzle;

[0022] The printhead includes a feed column, a heating chamber, and a nozzle, which are connected sequentially from top to bottom to form a material ejection path for 3D printing.

[0023] The heating chamber passes through the middle of the printhead nozzle cover and is fixed to the moving platform by the printhead nozzle cover;

[0024] The lower part of the heating chamber is provided with heat dissipation holes.

[0025] The wire feeding mechanism includes: a material wheel, a wire feeding drive motor, a wire feeding motor base, an L-shaped base, a T-shaped support, a wire feeding mechanism drive wheel, and a stop pin;

[0026] The material wheel is fixedly mounted on the upper surface of the stationary platform by a bracket. The material wheel is used to wind the material rod to provide filament for the print head.

[0027] The wire feeding motor base is fixed to the lower surface of the stationary platform, the wire feeding motor is fixedly installed at the rear end of the wire feeding motor base, and the L-shaped base is fixedly installed at the front end of the wire feeding motor base. The wire feeding motor base and the L-shaped base are provided with through holes for the output end of the wire feeding motor to pass through.

[0028] The L-shaped base has a boss at its front end, and the T-shaped base is set on the top of the boss and fixedly connected by a fixing screw. The fixing screw passes through the T-shaped base and the boss in sequence. A spring is provided between the fixing screw and the T-shaped base and the boss so that there is a gap between the T-shaped base and the boss for setting the drive wheel of the wire feeding mechanism.

[0029] The drive wheel of the wire feeding mechanism is located at the output end of the wire feeding motor.

[0030] The bottom of the T-shaped base is provided with a stop pin connecting part, the stop pin passes through the stop pin connecting part, and an adjusting wheel is provided at the protruding section of the stop pin. The adjusting wheel is used to adjust the distance between the adjusting wheel and the drive wheel of the wire feeding mechanism to match the material bar.

[0031] The T-shaped base and L-shaped base are respectively provided with through holes for the material rod to pass through, so that the material rod is located between the adjusting wheel and the drive wheel of the filament feeding mechanism, and is driven to the print head by the drive wheel of the filament feeding mechanism.

[0032] A test method for a teaching 3D printing experimental device based on a parallel robot arm, applied to the aforementioned teaching 3D printing experimental device based on a parallel robot arm, includes the following steps:

[0033] S1: Install strain sensors at the strain measurement points of the robot arm motion mechanism and the print head to obtain the elastic deformation parameters of the robot arm motion mechanism and the thermal deformation parameters of the print head.

[0034] S2: The theoretical position of the print head during the printing process is obtained through computer calculation;

[0035] S3 adjusts the forward and reverse rotation frequency of the servo motor and the number of rotor rotations to adjust the 3D printing test device to the preset printing speed;

[0036] Adjust the heating temperature of the heating chamber inside the printhead to the preset printing operating temperature;

[0037] The servo motor controls the robotic arm's motion mechanism to drive the print head, enabling it to perform 3D printing under preset printing speed and operating temperature conditions.

[0038] S4: Capture the actual position of the print head during the 3D printing process using an external high-speed camera and upload the image to a computer.

[0039] S5: Complete the printing process of the test piece and obtain the data from the strain sensor during the printing process, namely, the elastic deformation of the robot arm motion mechanism and the thermal deformation of the print head under the current printing speed and printing working temperature conditions.

[0040] The theoretical and actual positions of the print head during the printing process of the test piece are compared, and the motion error of the print head under the current printing speed and printing temperature conditions is calculated.

[0041] Based on the data from the strain sensor during the printing process and the motion error of the print head, the accuracy retention of the 3D printing experimental device is estimated.

[0042] S6: Return to step S2 and try again.

[0043] The method for calculating the accuracy retention of the 3D printing experimental device is as follows:

[0044] A spatial rectangular coordinate system O is established by computer based on the printing space of the printed test piece. -xyz The actual position P2(x2,y2,z2) of the print head is obtained by using a high-speed camera and compared with the theoretical position P1(x1,y1,z1) to obtain the motion error of the print head in the x, y, and z directions of the 3D printing experimental device under the current printing speed and operating temperature.

[0045] Δx=x1-x2, Δy=y1-y2, Δz=z1-z2

[0046] Where P1(x1,y1,z1) and P2(x2,y2,z2) represent the print head in the Cartesian coordinate system O, respectively. -xyz Theoretical coordinates and actual coordinates in the diagram;

[0047] The deviation between the theoretical and actual coordinates of the print head is ΔP = [Δx, Δy, Δz]. T ;

[0048] The ∞ norm of the deviation ΔP is calculated using a computer. ∞ To obtain the maximum processing error of the 3D printing head;

[0049] During repeated trials, plot ‖ΔP‖ ∞ The graph of the function f(t,‖ΔP‖ with respect to time t ∞ The printing accuracy retention characteristics under repeated processing and thermal error accumulation can be obtained through function graphs;

[0050] When f(t,‖ΔP‖ ∞ The value remains relatively small, i.e., the function f(t,‖ΔP‖) remains relatively small. ∞ When the value of the ordinate of the curve is small and the curve is stable, it indicates good printing accuracy retention.

[0051] (III) Beneficial Effects

[0052] This invention provides a teaching 3D printing experimental device and method based on a parallel manipulator. It can be combined with the needs of 3D printing science education for teenagers. During the experimental testing process, it combines the explanation of the working principle of 3D printing mechanism, 3D printing processing of workpieces based on different materials, and analysis of the influence of different processing parameters on the surface morphology and mechanical properties of workpieces. This deepens the popularization of 3D printing technology among teenagers and guides them to carry out performance improvement and innovation of 3D printed structures. Combined with the development of a human-computer interaction interface with popular science and test data display functions, it becomes an experimental device that integrates popular science education for teenagers and performance testing of 3D printing mechanisms.

[0053] By combining the print head with multiple parallel robotic arm motion mechanisms, the print head can move in multiple directions, which can meet the printing and testing needs of different shaped test pieces.

[0054] By installing strain sensors on force transmission components such as cranks and connecting rods in the robotic arm's motion mechanism, the elastic deformation of the corresponding components of the robotic arm's motion mechanism can be obtained.

[0055] The thermal deformation of the nozzle can be obtained by placing a strain sensor in the nozzle of the printhead.

[0056] The actual position of the print head during the printing process of the 3D printing experimental device can be obtained by using an independently set height camera.

[0057] The motion error of the 3D printing head can be obtained by comparing the actual position with the theoretical position. By adjusting the forward and reverse rotation frequency, rotation angle and printing working temperature of the servo motor, the motion error of the 3D printing head under different printing speed and temperature conditions can be obtained.

[0058] By conducting multiple tests using the 3D printing test apparatus of this invention, and combining data processing methods such as regression analysis, the accuracy retention of the 3D printing test apparatus under different printing conditions can be obtained and evaluated. Attached Figure Description

[0059] Figure 1 This is a structural schematic diagram (assembly drawing) of a teaching 3D printing experimental device based on a parallel manipulator according to the present invention;

[0060] Figure 2This is a schematic diagram (top view) of a teaching 3D printing experimental device based on a parallel manipulator according to the present invention;

[0061] Figure 3 This is a schematic diagram (assembly drawing) of the moving platform structure of a teaching 3D printing experimental device based on a parallel manipulator according to the present invention;

[0062] Figure 4 This is a schematic diagram of the print head structure of a teaching 3D printing experimental device based on a parallel manipulator according to the present invention;

[0063] Figure 5 This is an exploded view of the filament feeding mechanism of the print head of a teaching 3D printing experimental device based on a parallel manipulator according to the present invention.

[0064] Figure 6 This is a partial schematic diagram of the filament feeding mechanism of a teaching 3D printing experimental device based on a parallel robot arm according to the present invention.

[0065] [Explanation of Labels in the Attached Image]

[0066] 1: Aluminum profile frame, 2: Support platform, 3: Heated bed, 4: Servo motor, 5: Static platform, 6: Crank, 7: Material wheel, 8: First strain sensor, 9: Second strain sensor, 10: Spherical joint, 11: Active arm fixing column, 12: Connecting rod, 13: Third strain sensor, 14: Coupling, 15: Moving platform, 16: Moving platform connecting column, 17: Hex bolt, 18: Temperature sensor, 19: Nozzle head cover, 20: 21: Feed column; 22: Heating chamber; 23: Nozzle lower cover; 24: Nut; 25: Heat dissipation hole; 26: Fourth strain sensor; 27: Nozzle; 28: Cross screw; 29: Stop pin; 30: T-shaped base; 31: Material rod; 32: L-shaped base; 33: Wire feeding motor base; 34: Fixing screw; 35: Wire feeding mechanism drive wheel; 36: Print head; 37: Boss; 38: Stop pin connecting part; 39: Adjusting wheel. Detailed Implementation

[0067] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. In this document, directional terms such as "upper," "lower," etc., are used interchangeably with other directional terms. Figure 1 For reference.

[0068] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0069] Example 1:

[0070] See Figure 1-2 This embodiment provides a teaching 3D printing experimental device based on a parallel robot arm, which is used to test and evaluate the factors affecting the quality of 3D printed workpieces.

[0071] The 3D printing experimental setup includes a support mechanism, several robotic arm motion mechanisms, a filament feeding mechanism, a print head 36, and a performance testing module. The robotic arm motion mechanisms and the filament feeding mechanism are mounted on the support mechanism. The print head 36 connects to the robotic arm motion mechanisms and the filament feeding mechanism. The filament feeding mechanism feeds material rods 30 to the print head 36. The robotic arm motion mechanisms control the print head 36 to achieve 3D printing. The performance testing module is used to acquire experimental variables at strain measurement points. By acquiring variables under different conditions, the factors affecting the performance of the 3D printing mechanism can be analyzed. Strain measurement points are the detection points used to test components prone to deformation.

[0072] The support mechanism is used to support, hold, and fix the various components of the 3D printing experimental device. The support mechanism includes: aluminum profile frame 1, support platform 2, heated bed 3, and static platform 5.

[0073] The aluminum profile frame 1 includes several support columns and support beams. The support columns are set perpendicular to the ground, and the support beams are fixedly connected between every two adjacent support columns.

[0074] Optionally, the support beam can be fixed vertically to the support column, or it can be fixed at a certain angle to the support column, depending on the actual needs. In this embodiment, the support beam is fixed vertically to the support column. The support beam can be fixedly connected to the support column by bolts or welding.

[0075] The supporting beams include several upper beams and lower beams. The upper beams are located on the upper part of the supporting column, and the lower beams are located on the lower part of the supporting column.

[0076] The lower crossbeam is vertically fixed between two adjacent support columns, forming a horizontal frame around the support columns to accommodate the support platform 2. The support platform 2 is bolted to the top of the lower support crossbeam and supports the upper heated bed 3.

[0077] The adjustable heated bed 3 is used to support and cool the 3D printed workpiece. The heated bed 3 is set on the top of the support platform 2 by fixing bolts and height adjustment bolts. The fixing bolts are used to fix the heated bed 3 circumferentially, and the height adjustment bolts are used to adjust the support height of the heated bed 3.

[0078] The static platform 5 is fixedly installed on the upper surface of the upper crossbeam by fixing bolts. The static platform 5 is used to install the robot arm motion mechanism and the wire feeding mechanism, etc.

[0079] The robotic arm motion mechanism is set on the static platform 5. Several robotic arm motion mechanisms are connected in parallel. In this embodiment, three robotic arm motion mechanisms are connected in parallel. Adjacent robotic arm motion mechanisms are installed on the static platform 5 at an angle of 120 degrees to each other. That is, the included angle between adjacent robotic arm motion mechanisms is 120 degrees.

[0080] The robotic arm motion mechanism includes: a coupling 14, a crank 6, a pair of active arm fixing columns 11, a ball joint 10, a connecting rod 12, and a servo motor 4.

[0081] One end of the crank 6 is rotatably connected to the output end of the servo motor 4 via a coupling 14, and the crank 6 is set perpendicular to the output end of the servo motor 4.

[0082] The coupling 14 and the crank 6 are fixedly connected by a flange so that the servo motor 4 drives the coupling 14 to rotate, and at the same time drives the crank 6 to rotate.

[0083] The bottom of the connecting coupling 14 is provided with a fixed seat, and the coupling 14 and the servo motor 4 are fixed on the static platform 5 by the fixed seat and fixing bolts.

[0084] The active arm fixing post 11 is vertically fixed on the side walls on both sides of the crank 6. The spherical joint 10 is fixedly installed on the outer end of the active arm fixing post 11. The connecting rod 12 is rotatably connected to the crank 6 through the spherical joint 10, realizing the relative rotation between the crank 6 and the connecting rod 12, so that the crank 6 can drive the connecting rod 12 to move through the spherical joint 10.

[0085] See Figure 3 The lower end of the connecting rod 12 is also connected to a movable platform 15. The movable platform 15 is rotatably connected to the lower end of the connecting rod 12 via a movable platform connecting column 16. The movable platform 15 is used to mount the print head 36.

[0086] The moving platform 15 is disc-shaped, and several connecting seats are provided around the edge of the moving platform 15. The center of the connecting seat is provided with a first through hole for the moving platform connecting column 16 to pass through. The moving platform connecting column 16 is inserted into the connecting seat through the first through hole, and the connecting seat cooperates with the moving platform connecting column 16 to realize the rotatable connection between the moving platform 15 and the connecting rod 12.

[0087] The servo motor 4 controls the crank 6 to drive the connecting rod 12 to move. The connecting rod 12 drives the moving platform 15 to adjust and control the position and posture of the moving platform 15. By adjusting the moving platform 15, the print head 36 is driven to realize the 3D printing of the workpiece at a predetermined spatial position.

[0088] See Figure 4 The print head 36 is fixed on the moving platform 15 by a hex bolt 17 and a nut 23. The print head 36 includes a print head nozzle cover and a print head nozzle.

[0089] The printhead cover is used to fix and support the printhead, and also facilitates the fixing of the printhead onto the moving platform 15. The printhead cover includes an upper cover 19 and a lower cover 22. The upper cover 19 is located above the lower cover 22. Hex bolts 17 pass through the upper cover 19, the lower cover 22 and the moving platform 15 in sequence, and are fixed to the moving platform 15 by nuts 23.

[0090] The printhead includes a feed column 20, a heating chamber 21, and a nozzle 26, which are connected sequentially from top to bottom to form a 3D printing spray path.

[0091] The printhead cover 19 and the printhead lower cover 22 are provided with a second through hole for the printhead nozzle to pass through.

[0092] The feed column 20 is located at the top of the heating chamber 21, which passes through the middle of the printhead nozzle cover and is mounted on the moving platform 15 via the lower nozzle cover 22.

[0093] Nozzle 26 is located at the bottom of feed column 20. Nozzle 26 is used to spray heated liquid printing material as needed to achieve 3D printing of workpiece.

[0094] The lower part of the heating chamber 21 is provided with heat dissipation holes 24, which are used to dissipate heat from the inside of the heating chamber 21, cool and adjust the temperature of the printing material inside the heating chamber.

[0095] The heating chamber 21 can be connected to an external heat dissipation device, and the nozzle temperature can be actively adjusted by controlling the heat dissipation device. Optionally, the heat dissipation device in this embodiment is a cooling fan, or a suitable cooling device can be selected according to actual needs.

[0096] See Figure 1 , Figure 5 , Figure 6 The wire feeding mechanism is set on the static platform 5. The wire feeding mechanism includes: material wheel 7, wire feeding drive motor 33, wire feeding motor base 32, L-shaped base 31, T-shaped support 29, wire feeding mechanism drive wheel 35, and stop pin 28.

[0097] The material wheel 7 is fixedly mounted on the upper surface of the static platform 5 by a bracket. The material wheel 7 is used to wind the material rod 30 to provide filament for the print head 36.

[0098] The wire feeding motor base 32 is fixed on the lower surface of the stationary platform 5, and the wire feeding motor 33 is fixedly installed at the rear end of the wire feeding motor base 32. The wire feeding motor base 32 is provided with a third through hole for the output end of the wire feeding motor 33 to pass through.

[0099] The front end of the L-shaped base 31 is provided with a boss 37 so that the side of the L-shaped base 31 is L-shaped. The rear end of the L-shaped base 31 is fixedly connected to the front end of the wire feeding motor base 32 by a cross screw 27. The L-shaped base 31 is provided with a fourth through hole coaxially with the third through hole. The fourth through hole is used for the output end of the wire feeding motor 33 to pass through.

[0100] The T-shaped base 29 is set on the top of the boss 37 and is fixedly connected by the T-shaped base fixing screw 34. The fixing screw 34 passes through the T-shaped base 29 and the boss 37 in sequence. A spring is provided between the fixing screw 34 and the T-shaped base 29 and the boss 37, so that there is a gap between the T-shaped base 29 and the boss 37 for setting the drive wheel 35 of the wire feeding mechanism.

[0101] The output end of the wire feeding motor 33 passes through the wire feeding motor base 32 and the L-shaped base 31 in sequence. The drive wheel 35 of the wire feeding mechanism is located at the output end of the wire feeding motor 33. The drive wheel 35 of the wire feeding mechanism is located between the T-shaped base 29 and the boss 37.

[0102] The bottom of the T-shaped base 29 is provided with a stop pin connecting part 38, the stop pin 28 passes through the stop pin connecting part 38, and an adjusting wheel 39 is provided at the protruding part of the stop pin 28.

[0103] The upper surface of the T-shaped base 29 is designed with a fifth through hole and a sixth through hole. The fifth through hole is used to guide the material rod 30 wire wound on the material wheel 7 to be fed to the print head 36 under the drive of the wire feeding mechanism drive wheel 35. The sixth through hole is used to install the fixing screw 34 to connect and fix the T-shaped base 29 to the L-shaped base 31.

[0104] The L-shaped base 31 has a seventh through hole corresponding to the fifth through hole of the T-shaped base 29, through which the material rod 30 passes. The material rod 30, as the printing material for 3D printing, passes through the seventh through hole, so that the material rod 30 is located between the adjusting wheel 39 and the active wheel 35 of the filament feeding mechanism. The adjusting wheel 39 is used to adjust the distance between the adjusting wheel 39 and the active wheel 35 of the filament feeding mechanism to match the material rod 30.

[0105] The surface of the axle of the drive wheel 35 of the filament feeding mechanism is machined with grooves, and the material rod 30 is dragged to the print head as needed by adjusting the gap between it and the stop pin 28.

[0106] The lower end of the material rod 30 is inserted into the feed column 20. The filament feeding motor 33 drives the drive wheel 35 of the filament feeding mechanism to rotate, which drives the material rod 30 through the T-shaped base 29 and the L-shaped base 31 to feed the material into the feed hole of the feed column 20. The lower end of the material rod 30 is fed into the heating chamber 21 through the feed hole. The heating chamber 21 heats the material rod 30 to form liquid printing material for 3D printing.

[0107] During the process of the servo motor 4 driving the print head 36 to work through the crank 6 and connecting rod 12, the crank 6 and connecting rod 12 will undergo elastic deformation, and the nozzle 26 of the print head 36 will undergo thermal deformation. Therefore, it is necessary to detect the temperature of the deformed components and the print head 36, and to comprehensively consider the factors that cause deformation based on the obtained detection data.

[0108] The performance testing module is used to acquire the test variables of the corresponding strain measurement points. The performance testing module includes: a first strain sensor 8 and a second strain sensor 9 set on the crank 6, a third strain sensor 13 set on the connecting rod 12, a fourth strain sensor 25 set on the nozzle 26, a temperature sensor 18 connected to the heating chamber 21, and a high-speed camera for acquiring the spatial position and attitude of the moving platform 15.

[0109] Among them, the strain sensors at crank 6 and connecting rod 12 use conventional resistance strain gauges to measure the elastic deformation of structural components such as crank 6 and connecting rod 12 (reading strain values). For nozzle 26, which has a high temperature and complex structural thermal deformation, a high-temperature, high-precision triaxial strain gauge is selected to obtain the structural thermal deformation at nozzle 26. Then, combined with the temperature sensor 18 installed at the temperature measurement point, the nozzle temperature load is obtained, and the thermal deformation results of nozzle 26 under different printing media and different heating temperatures are obtained.

[0110] When the servo motor 4 drives the print head 36 to work via the crank 6 and connecting rod 12, the crank 6 deforms most significantly under the influence of the motor torque at the connection points between the flange of the servo motor 4 and the crank 6, and between the crank 6 and the connecting rod 12. These are the first and second strain measurement points in this embodiment. A first strain sensor 8 and a second strain sensor 9 are respectively installed at the first and second strain measurement points to obtain the elastic deformation at the connection points at both ends of the crank 6.

[0111] During operation, the connecting rod 12 is mainly subjected to tensile and compressive loads. Therefore, a third strain sensor 13 is set at the middle position of the connecting rod, which is the third strain measuring point in this embodiment, to obtain the elastic deformation of the connecting rod 12.

[0112] Optionally, the strain sensor can be adjusted according to the different operating parameters of the 3D printing test device and the actual conditions.

[0113] The temperature load generated by heating the printing material near the nozzle 26 can cause thermoelastic deformation at the nozzle 26. To address this, a high-precision high-temperature strain gauge is installed at the nozzle 26, specifically at the fourth strain measurement point in this embodiment, to obtain the thermal deformation of the nozzle 26 in various directions, thereby collecting the thermal deformation error of the printhead under different temperature loads.

[0114] After the strain sensor and temperature sensor 18 are installed according to the test requirements, when the servo motor 4 drives the print head to work at different printing speeds through the crank 6 and connecting rod 12, the strain sensor can obtain the elastic deformation of structural components such as the crank 6 and connecting rod 12 in real time. Through the fourth strain sensor 25 installed on the print head 36 and the temperature sensor 18 connected to the heating cavity 21, the thermal deformation generated under different printing working temperatures can be obtained. The coupling and superposition effect of the two will affect the motion accuracy of the print head.

[0115] The high-speed camera is set up independently and installed outside the 3D printing test device. The high-speed camera is used to capture the actual position of the moving platform 15. The printing end of the high-speed camera is directly facing the middle part of the printed image of the print head 36. It can observe the coordinate origin on the heated bed 3 and capture the entire 3D printing image, which is convenient for continuous observation and capture of the constantly moving platform 15 during the printing process.

[0116] Example 2:

[0117] This embodiment provides an experimental method for a teaching 3D printing experimental device based on a parallel robotic arm, including the following steps:

[0118] Step 1: Connect the robotic arm motion mechanism and print head 36, which require printing error measurement and accuracy retention testing, to the support mechanism.

[0119] Step 2: Install strain sensors for measuring the elastic and thermal deformation of the structure on crank 6, connecting rod 12, and print head 36.

[0120] Step 3: Calculate the theoretical printing position of the test piece to be printed using a computer.

[0121] Step 4: Adjust the forward and reverse rotation frequency and the number of rotor rotations of servo motor 4 to set the 3D printing test device to the preset printing speed. The number of rotor rotations is the output angle of servo motor 4.

[0122] Adjust the heating temperature of the heating chamber 21 to the preset printing working temperature.

[0123] Step 5: Control the robotic arm motion mechanism to move the print head 36 on the drive platform 15, so that it can perform 3D printing processing under the preset printing speed and printing working temperature.

[0124] An external high-speed camera captures the actual position of the print head 36 during the 3D printing process and uploads the image to a computer.

[0125] Step 6: Complete the printing process of the test piece and obtain the data from the strain sensor during the printing process, namely, the elastic deformation of crank 6 and connecting rod 12 under the current printing speed and printing working temperature, as well as the thermal deformation of print head 36.

[0126] By comparing the theoretical and actual printing positions of the printed test piece, the print head movement error under the current printing speed and printing operating temperature conditions is calculated.

[0127] Based on the data from strain sensors during the printing process and the motion error of the print head, the accuracy retention of the 3D printing experimental device is estimated.

[0128] Step 7: Return to step 4 and reset the forward and reverse frequency and the number of rotor rotations of servo motor 4, and test again.

[0129] Example 3:

[0130] Specifically, the calculation method for the print head motion error of the 3D printing experimental device is as follows:

[0131] To accurately measure the motion precision of the 3D printing experimental device, a spatial rectangular coordinate system O is established with the left corner of the front end of the heated bed 3 as the origin O. -xyz Based on the forward and reverse rotation frequency and output angle of servo motor 4, and combined with the spatial rectangular coordinate system, the theoretical printing position, i.e., the coordinates P1(x1,y1,z1), is calculated through servo motor programming of the robotic arm. Here, x1, y1, and z1 are the coordinate values ​​of P1 in the x, y, and z directions, respectively.

[0132] During the 3D printing process, a high-speed camera captures the actual position of the print head 36 and uploads it to a computer. The computer then calculates the actual spatial and positional orientation of the print head 36 in the same Cartesian coordinate system, i.e., the coordinates P2(x2, y2, z2) of its actual position. Here, x2, y2, and z2 are the coordinate values ​​of P2 in the x, y, and z directions, respectively.

[0133] By comparing the actual position with the theoretical position, we can obtain the motion error of the printhead in the x, y, and z directions at different printing speeds and operating temperatures:

[0134] Δx=x1-x2, Δy=y1-y2, Δz=z1-z2

[0135] The aforementioned deviation ΔP = [ΔxΔyΔz] is calculated at each point along the printhead's trajectory. TIt can obtain the difference between the actual printing position and the theoretical position of the print head under different printing speeds and operating temperatures, forming the processing error of the 3D print head under different printing conditions (affected by different parameters).

[0136] Specifically, by controlling the servo motor 4 to drive the robotic arm motion mechanism, which in turn drives the platform 15 to produce translational motion in the x, y, and z directions and relative rotation around the three coordinate axes, the spatial position and attitude of the print head are controlled. The printing speed of the device is adjusted by changing the forward and reverse rotation frequency and the rotation angle of the servo motor 4.

[0137] The morphological characteristics of the printed test piece to be printed are programmed by computer to control the motion state of servo motor 4, providing theoretical position input for the print head's motion posture and spatial coordinates. The actual position P2(x2,y2,z2) of the print head 36 is acquired by a high-speed camera and compared with the theoretical position P1(x1,y1,z1). The difference Δz in the z-direction is calculated to obtain the morphological error of the actual printed workpiece surface.

[0138] During the motion accuracy measurement process, under different printing speeds and operating temperatures, the elastic deformation of crank 6 and connecting rod 12, as well as the thermal deformation of print head 36, are obtained by strain sensors. Combined with the print head motion error of the 3D printing test device, the accuracy retention of the 3D printing test device is inferred.

[0139] Specifically, the method for calculating the accuracy retention of the 3D printing experimental device is as follows:

[0140] The ∞ norm of the deviation ΔP is calculated using a computer. ∞ The maximum processing error of the 3D printing head can be determined. During repeated processing, the parameter ||ΔP|| is plotted. ∞ The graph of the function f(t,‖ΔP‖ with respect to time t ∞ The printing accuracy retention characteristics under repeated processing and thermal error accumulation can be obtained through the function graph curve.

[0141] When f(t,‖ΔP‖ ∞ The value remains relatively small, i.e., the function f(t,‖ΔP‖) remains relatively small. ∞ When the value of the ordinate of the curve is small and the curve is stable, it indicates good printing accuracy retention.

[0142] The beneficial effects of this invention are:

[0143] This invention provides a teaching 3D printing experimental device and method based on a parallel robot arm, used to test and evaluate the factors affecting the quality of 3D printed workpieces.

[0144] By combining the print head 36 with multiple parallel robotic arm motion mechanisms, the print head 36 can move in multiple directions, which can meet the needs of 3D printing testing for printed test pieces of different shapes.

[0145] By installing strain sensors on force transmission components such as crank 6 and connecting rod 12 in the robotic arm motion mechanism, the elastic deformation of the corresponding components of the robotic arm motion mechanism can be obtained.

[0146] The thermal deformation of the nozzle 26 can be obtained by setting a strain sensor in the nozzle 26 of the printhead 36.

[0147] The operating temperature of the printhead 36 can be obtained by installing a temperature sensor 18 outside the heating chamber 21 of the printhead 36.

[0148] The actual position of the print head 36 of the 3D printing experimental device during the printing process can be obtained by using an independently set height camera.

[0149] By adjusting the forward and reverse rotation frequency, rotation angle, and printing operating temperature of the servo motor, the motion error of the 3D print head under different printing speeds and temperatures was calculated.

[0150] Through multiple experiments and combined with data processing methods such as regression analysis, the accuracy retention of the 3D printing experimental device under different printing conditions was obtained and evaluated.

[0151] Furthermore, the 3D printing experimental device of this invention can be combined with the needs of 3D printing science education for teenagers. During the experimental testing process, it combines the explanation of the working principle of 3D printing mechanism, 3D printing processing of workpieces based on different materials, and the analysis of the influence of different processing parameters on the surface morphology and mechanical properties of workpieces. This deepens the popularization of 3D printing technology among teenagers, guides teenagers to carry out performance improvement and innovation of 3D printed structures, and, combined with the development of a human-computer interaction interface with popular science and test data display functions, becomes an experimental device that integrates popular science education for teenagers and performance testing of 3D printing mechanisms.

[0152] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0153] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0154] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0155] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0156] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A teaching 3D printing experimental device based on a parallel robotic arm, characterized in that, include: Support mechanism, several parallel robotic arm motion mechanisms, filament feeding mechanism, print head (36) and performance testing module; Several robotic arm motion mechanisms are arranged on the top of the support mechanism. The lower end of the robotic arm motion mechanism is connected to the print head (36). The robotic arm motion mechanism drives the print head (36) to perform 3D printing through a servo motor (4). The filament feeding mechanism is disposed on the support mechanism and is used to feed the material rod (30) for 3D printing to the print head (36). The performance testing module includes: several strain sensors, a high-speed camera and a temperature sensor (18). The strain sensors are set at the strain measurement points of the 3D printing test device. The strain measurement points are the crank (6) of the manipulator motion mechanism, the connecting rod (12) of the manipulator motion mechanism and the nozzle (26) of the print head (36). The temperature sensor (18) is connected to the heating chamber (21) of the print head (36) to obtain the elastic deformation parameters of the manipulator motion mechanism and the thermal deformation parameters of the print head (36). The high-speed camera is set independently of the support mechanism and is used to obtain the actual position of the print head (36) during the printing process.

2. The 3D printing experimental device for teaching based on a parallel robotic arm according to claim 1, characterized in that, The support structure includes: an aluminum profile frame (1), a support platform (2), a heated bed (3), and a static platform (5); The static platform (5) is located on the upper part of the aluminum profile frame (1), the support platform (2) is located on the lower part of the aluminum profile frame (1), the heated bed (3) is located on the top of the support platform (2), and the height of the heated bed (3) is adjustable.

3. The 3D printing experimental device for teaching based on a parallel robotic arm according to claim 2, characterized in that, Several of the aforementioned robotic arm motion mechanisms are arranged around the static platform (5), and the robotic arm motion mechanisms further include: the crank (6) and the connecting rod (12). One end of the crank (6) is rotatably connected to the output end of the servo motor (4) via a coupling (14), and the crank (6) is set perpendicular to the output end of the servo motor (4); The bottom of the coupling (14) is provided with a fixed seat, through which the coupling (14) and the servo motor (4) are fixed on the static platform (5); The crank (6) is provided with a pair of active arm fixing columns (11) at the end away from the coupling (14). The outer end of the active arm fixing column (11) is provided with a ball joint (10). The connecting rod (12) is rotatably connected to the crank (6) through the ball joint (10).

4. The 3D printing experimental device for teaching based on a parallel robotic arm according to claim 3, characterized in that, The lower end of the connecting rod (12) of all the robotic arm motion mechanisms is also connected to a moving platform (15). The moving platform (15) is rotatably connected to the connecting rod (12) through the moving platform connecting column (16). The moving platform (15) is used to carry the print head (36).

5. The 3D printing experimental device for teaching based on a parallel manipulator according to claim 4, characterized in that, The print head (36) is fixed to the moving platform (15) by means of hex bolts (17) and nuts (23). The print head (36) includes: a print head nozzle cover and a print head nozzle. The printhead includes a feed column (20), a heating chamber (21), and a nozzle (26), which are connected from top to bottom to form a 3D printing spray path; The heating chamber (21) passes through the middle of the printhead nozzle cover and is fixed to the moving platform (15) by the printhead nozzle cover; The heating chamber (21) is provided with heat dissipation holes (24) in the lower part.

6. The 3D printing experimental device for teaching based on a parallel manipulator according to claim 2, characterized in that, The wire feeding mechanism includes: a material wheel (7), a wire feeding drive motor (33), a wire feeding motor base (32), an L-shaped base (31), a T-shaped base (29), a wire feeding mechanism drive wheel (35), and a stop pin (28). The material wheel (7) is fixedly mounted on the upper surface of the stationary platform (5) by a bracket. The material wheel (7) is used to wind the material rod (30) to provide filament for the print head (36). The wire feeding motor base (32) is fixed on the lower surface of the stationary platform (5), the wire feeding motor (33) is fixedly disposed at the rear end of the wire feeding motor base (32), and the L-shaped base (31) is fixedly disposed at the front end of the wire feeding motor base (32). The wire feeding motor base (32) and the L-shaped base (31) are provided with through holes for the output end of the wire feeding motor (33).

7. The 3D printing experimental device for teaching based on a parallel robotic arm according to claim 6, characterized in that, The front end of the L-shaped base (31) is provided with a boss (37), and the T-shaped base (29) is set on the top of the boss (37) and fixedly connected by a fixing screw (34). The fixing screw (34) passes through the T-shaped base (29) and the boss (37) in sequence. The fixing screw (34) is provided with a spring between the T-shaped base (29) and the boss (37) so that there is a gap between the T-shaped base (29) and the boss (37) for setting the drive wheel (35) of the wire feeding mechanism. The drive wheel (35) of the wire feeding mechanism is located at the output end of the wire feeding motor (33).

8. The 3D printing experimental device for teaching based on a parallel manipulator according to claim 7, characterized in that, The bottom of the T-shaped base (29) is provided with a stop pin connection part (38), the stop pin (28) passes through the stop pin connection part (38), and an adjustment wheel (39) is provided at the protruding section of the stop pin (28). The adjustment wheel (39) is used to adjust the distance between the adjustment wheel (39) and the active wheel (35) of the wire feeding mechanism to match the material bar (30). The T-shaped base (29) and L-shaped base (31) are respectively provided with through holes for the material rod (30) to pass through, so that the material rod (30) is located between the adjusting wheel (39) and the active wheel (35) of the filament feeding mechanism, and is driven to the print head (36) by the active wheel (35) of the filament feeding mechanism.

9. A test method for a teaching 3D printing experimental device based on a parallel manipulator, characterized in that, The teaching 3D printing experimental device based on a parallel manipulator as described in any one of claims 1-8 includes the following steps: S1: Install strain sensors at the strain measurement points of the robotic arm motion mechanism and the print head (36) to obtain the elastic deformation parameters of the robotic arm motion mechanism and the thermal deformation parameters of the print head (36); S2: The theoretical position of the print head (36) during the printing process is obtained by computer calculation; S3 adjusts the forward and reverse frequency and the number of rotor rotations of the servo motor (4) to adjust the 3D printing test device to the preset printing speed; Adjust the heating temperature of the heating chamber (21) inside the printhead (36) to the preset printing working temperature; The servo motor (4) controls the robotic arm motion mechanism to drive the print head (36) to move, enabling it to perform 3D printing processing under the preset printing speed and printing working temperature. S4: Capture the actual position of the print head (36) during the 3D printing process using an external high-speed camera and upload it to the computer; S5: Complete the printing process of the test piece and obtain the data of the strain sensor during the printing process, that is, obtain the elastic deformation of the robot motion mechanism under the current printing speed and printing working temperature conditions, as well as the thermal deformation of the print head (36); The theoretical and actual positions of the print head (36) during the printing process of the test piece are compared, and the motion error of the print head under the current printing speed and printing working temperature conditions is calculated. Based on the data from the strain sensor during the printing process and the motion error of the print head, the accuracy retention of the 3D printing experimental device is estimated. S6: Return to step S2 and try again.

10. The test method for the teaching 3D printing experimental device based on a parallel manipulator according to claim 9, characterized in that, The method for calculating the accuracy retention of the 3D printing experimental device is as follows: A spatial rectangular coordinate system O is established by computer based on the printing space of the printed test piece. -xyz The actual position of the print head (36) is obtained through a high-speed camera. , and theoretical position By comparison, the motion errors of the print head in the x, y, and z directions of the 3D printing experimental setup under the current printing speed and operating temperature were obtained: ； in, , The print head (36) is located in the rectangular coordinate system O. -xyz Theoretical coordinates and actual coordinates in the diagram; That is, the deviation between the theoretical coordinates and the actual coordinates of the print head (36) is ; The deviation was solved by computer. of norm To obtain the maximum processing error of the 3D printing head; During repeated trials, the plots were drawn. Graph of the function with respect to time t The printing accuracy retention characteristics under repeated processing and thermal error accumulation are obtained through function graphs.

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