3D printing equipment and printing control method thereof

Abstract

The invention belongs to the technical field of 3D printing, relates to 3D printing equipment and a printing control method thereof, and solves the problems that printing parameters cannot be adjusted in real time and the printing effect cannot be ensured. The 3D printing equipment comprises a mechanical arm controlled by an industrial robot, a printing device is arranged on the mechanical arm, the industrial robot and the printing device are connected with an upper computer, the printing device comprises a material storing and feeding mechanism and a screw extrusion mechanism which are arranged on a fixing support, and the discharging end of the material storing and feeding mechanism is connected with the feeding end of the screw extrusion mechanism; the upper computer comprises a three-dimensional model layered slicing module, a path optimization module and a dynamic cooperative control module. A laser distance measuring sensor is arranged on the outer side of a nozzle of the printing device and used for synchronously adjusting the motion trail of the mechanical arm. According to the equipment, the melt extrusion type printing mechanism is adopted, the product performance is improved, the application range of 3D printing is expanded, cooperation of the printing equipment and the mechanical arm is enhanced, specific parameters can be adjusted according to actual operation, and the printing quality is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing, and at the same time involves the cross - technical field of electronic digital data processing and industrial automation control. Specifically, it includes a high - precision 3D printing system based on real - time data processing, intelligent algorithm optimization, and closed - loop feedback. Background Art

[0002] Additive manufacturing technology, commonly known as 3D printing, is a rapid prototyping technology. Based on digital model files and slices, it constructs objects by layer - by - layer stacking of heated and melted polymer 3D printing wires. It can not only effectively improve the material utilization rate but also quickly manufacture complex structures that are difficult to process by traditional processes.

[0003] However, in the existing 3D printing technologies, the following problems generally exist: 1. Low efficiency of data processing and layer slicing. In traditional 3D printing technologies, the layer - slicing process of 3D models usually uses fixed parameters (such as layer height, filling density), which cannot be dynamically adjusted according to material properties (such as melt index, thermal shrinkage rate). For example, for high - viscosity materials or complex geometric models, fixed parameters may lead to redundant support structures or insufficient inter - layer bonding force; in addition, the Gcode instructions generated by slicing lack structured data management, and the single - thread parsing efficiency is low, making it difficult to meet the high - real - time control requirements of large - size models.

[0004] 2. Insufficient motion control accuracy. Existing robotic arm trajectory planning mostly relies on linear interpolation algorithms, with poor path smoothness. Mechanical vibrations are easily caused during high - speed movement, resulting in ripples on the printing surface or layer - to - layer misalignment; at the same time, the rotational speed control of the screw extruder is usually set based on empirical formulas or static parameters, without considering the dynamic characteristics of material viscosity changing with temperature. When the extrusion force is mismatched with the movement speed of the robotic arm, it is easy to cause material breakage or stacking defects, and the extrusion non - uniformity rate is generally higher than 15%.

[0005] 3. Lack of intelligence and collaborative control. In traditional solutions, the movement of the robotic arm and extrusion control are mostly independent open - loop systems, lacking real - time collaboration and adaptive compensation capabilities. For example, when material rheological properties change (such as the viscosity difference between PLA and ABS) or environmental temperature fluctuates, fixed control parameters are difficult to ensure the stability of the extrusion volume; in addition, existing technologies do not fully utilize intelligent algorithms (such as neural networks, machine learning) to optimize process parameters, and process optimization relies on manual trial - and - error, which is time - consuming and difficult to ensure consistency.

[0006] 4. Weak data storage and feedback mechanism. Existing systems usually lack efficient process data management capabilities. Historical printing parameters (such as speed, temperature, material consumption) are not structuredly stored or encrypted for transmission, making it difficult to support data - driven process optimization; at the same time, the closed - loop feedback mechanism is mostly limited to local sensors (such as temperature sensors), without integrating high - precision displacement detection and real - time dynamic correction functions. Summary of the Invention

[0007] The first object of the present invention is to address the above problems existing in the prior art. By integrating electrical digital data processing and intelligent control algorithms, it solves the industry pain points of inefficient data processing, motion-extrusion mismatch, and insufficient adaptability in traditional 3D printing, and provides a 3D printing device for manufacturing high-precision complex parts.

[0008] To achieve this object of the present invention, the following technical solutions can be adopted: A 3D printing device includes a robotic arm controlled by an industrial robot. A printing device is provided on the robotic arm through a fixed bracket. The industrial robot and the printing device are respectively connected to a host computer. The printing device includes a material storage and feeding mechanism and a screw extrusion mechanism. The discharge end of the material storage and feeding mechanism is connected to the feeding end of the screw extrusion mechanism; The host computer includes: Three-dimensional model layer slicing module: used to generate layer slicing data from the input three-dimensional model data through a mesh division algorithm. The layer slicing data includes the slice layer height (h) and the filling density parameter, and is transmitted to the path planning module through a structured data transmission protocol; Path planning module: generates a robotic arm motion trajectory based on the layer slicing data, and uses a parametric curve interpolation algorithm to smooth the trajectory. The optimized trajectory data is transmitted to the robotic arm controller in real time through an industrial communication protocol; Dynamic collaborative control module: continuously monitors the deviation between the printing speed (V′) and the target speed (V), and corrects the rotational speed (N) of the screw drive motor through a proportional-integral control algorithm. The calculation formula is: , where and are PID control parameters; Feedback compensation module: The displacement detection device provided at the printing nozzle is used to continuously collect the nozzle end position deviation Δx in real time, and generate a speed correction signal to synchronously adjust the robotic arm motion trajectory. The speed correction signal satisfies where is the dynamic compensation parameter.

[0009] The 3D printing device of the present invention mainly consists of a robotic arm and a printing device. The printing device is arranged on the robotic arm, and the movement of the printing device is controlled by the robotic arm, with a larger printing range, lower environmental requirements, and lower requirements for the flatness of the bottom plate. In the printing device, a material storage and feeding mechanism is used to store raw material particles and convey the raw material particles to a screw extrusion mechanism when needed. The screw extrusion mechanism specifically heats and softens the raw material particles and extrudes them to the corresponding positions to achieve the purpose of printing. Compared with wire printers, screw extruders have a wider range of material selection, can use more types of materials, can effectively reduce raw material costs, and can also increase the flow rate and shorten the printing time. The upper computer is connected to the industrial robot and the printing device at the same time, and is used to coordinate the movement of the robotic arm and the raw material output of the printing device, and can realize functions such as empty running, real-time flow control, and speed feedback flow control. At the same time, it is more convenient and fast in model slicing and point position processing, and has greater advantages during printing debugging, can more clearly understand the operation of the program, and can more easily find and solve problems. In addition, through neural network compensation and closed-loop feedback mechanisms, dynamic matching of printing speed and extrusion amount is achieved, and the problem of uneven extrusion caused by changes in material viscosity is solved. B-spline curve interpolation is used to reduce the high-frequency vibration of the robotic arm. Among them, the industrial robot controls the movement of the robotic arm in the x, y, and z axes, with flexible movement, which is prior art and its specific structure will not be elaborated in detail.

[0010] Among them, the dynamic cooperative control module of the upper computer calculates the speed deviation e(t) = V′ - V at a period of 1 ms by collecting the printing speed V′ fed back by the robotic arm encoder in real time, and tunes the PID parameters (K P = 0.5, K I = 0.2) based on the Ziegler-Nichols method. The corrected motor speed N′ is transmitted to the screw drive motor through the CAN bus, and the response delay < 10 μs. In the dynamic PID algorithm, the time window of the integral term is a rolling window updated in real time, and is updated every 1 ms (synchronized with the control period of the upper computer). For example, when the real-time speed deviation e(t) exceeds the threshold (such as ±5 mm / s), the integrator is reset to avoid cumulative errors. The parameter tuning logic adopts the Ziegler-Nichols tuning method, and determines the critical gain K u and the oscillation period T u through a step response test, and finally sets , .

[0011] In the above 3D printing device, the mesh generation algorithm is the Marching Cube algorithm, and the layer slicing data is stored in a structured database and transmitted through the JSON protocol; The parametric curve interpolation algorithm is the B-spline curve interpolation algorithm, and the industrial communication protocol is the Profinet protocol; The proportional-integral control algorithm is a dynamic PID algorithm, and the control parameters 、 are adaptively adjusted according to the type of printing material; The displacement detection device is a laser ranging sensor, whose sampling frequency is not lower than 1 kHz, and the differential calculation of the position deviation Δx is executed in real time by the host computer.

[0012] In the above 3D printing device, the material storage and feeding mechanism includes a material storage barrel, the upper end of the material storage barrel is provided with a feeding port, the lower end is connected to a screw extrusion mechanism through a feeding pipe, the material storage barrel is also provided with an air inlet and an air outlet, an air pump assembly is connected to the air inlet, a filter screen through which raw material particles cannot pass is arranged inside the air outlet, and a vibration motor is also connected to the feeding pipe through a motor fixing piece.

[0013] The material storage barrel is used to store raw material particles, the feeding port at its upper end is used to add raw material particles, and the lower end conveys the raw materials to the screw extrusion mechanism through the feeding pipe. In order to improve the rate of raw material particles entering from the feeding port, a pneumatic assistance structure is also arranged on the material storage barrel. Specifically, the structure generates a high-speed air flow through the air pump assembly. The air flow is input from the air inlet and output from the air outlet. The low pressure generated during the air flow process sucks in the raw material particles, improving the feeding rate. At the same time, the high-speed air flow can also carry away the dust between the raw material particles, improving the 3D printing quality. In order to ensure the smooth transmission of raw material particles in the feeding pipe, a vibration motor is connected to the feeding pipe to avoid the blockage of raw material particles by vibration. The motor fixing piece is clamped on the feeding pipe by a set of semi-circular hoop plates and fixed by bolts, with flexible detachability.

[0014] In the above 3D printing device, the screw extrusion mechanism includes a screw sleeve and a feeding screw rotatably connected inside the screw sleeve. The upper end of the feeding screw is connected to a screw driving motor through a reducer. The upper end of the screw sleeve is connected to the discharging end, and the lower end is connected to a nozzle. A heating structure is arranged between the screw sleeve and the nozzle.

[0015] A feeding screw with an outer diameter adapted to its inner diameter is arranged inside the screw sleeve. The screw driving motor is used to drive the rotation of the feeding screw. Raw material particles are input into the upper end of the screw sleeve and are squeezed and conveyed downward under the rotation of the feeding screw. The heating structure is used to soften the raw material particles to ensure that the molten raw materials are output from the lower nozzle. The cooperation between the screw sleeve and the feeding screw is prior art and will not be specifically elaborated.

[0016] As an optimization, the upper end of the feeding screw is connected to the reducer through a coupling. The reducer is connected to the screw driving motor. A motor cooling fan is arranged on the side of the screw driving motor, and the motor cooling fan is fixed on a fixing bracket.

[0017] The feeding screw is drivingly connected to the output end of the screw driving motor through a coupling and a speed reducer. The motor cooling fan is used to blow air on the screw driving motor for heat dissipation to prevent the motor from overheating.

[0018] In the above 3D printing device, the heating structure includes at least one annular heating coil axially distributed on the outer wall of the screw sleeve, and a heating block detachably fixed to the nozzle through a connecting screw head. A temperature measurement relief hole is provided on the annular heating coil, and a temperature sensor connected to the outer wall of the screw sleeve is provided in the temperature measurement relief hole, and / or a temperature sensor is provided between the annular heating coils.

[0019] Specifically, the heating structure is realized by an annular heating coil circumferentially arranged on the screw sleeve. The annular heating coil can be a ceramic heating coil, which is used to heat the screw sleeve to soften the raw material particles. Moreover, a heating block is also provided on the nozzle. The heating block can be a brass heating block with good heat conduction effect to ensure that the raw material has a good molten state when output from the nozzle. In addition, a temperature sensor is connected to the screw sleeve to detect the sleeve temperature, so as to accurately control the temperature. The temperature sensor is located in the temperature measurement relief hole of the annular heating coil to improve the accuracy of the measured temperature.

[0020] As an optimization, the heating block is square, and a connecting hole is axially and vertically penetrated. The connecting hole is sleeved with the connecting screw head. The upper part of the connecting screw head is provided with an external thread section adapted to the internal thread at the lower end of the screw sleeve, and the lower part is provided with a sleeve part adapted to the inner diameter of the connecting hole. A first through hole is axially penetrated. An internal thread adapted to the external thread of the nozzle is provided at the lower part of the first through hole. A hexagonal screwing part is provided between the sleeve part and the external thread section. The external thread section is screwed to the lower end of the screw sleeve, the nozzle is screwed to the lower end of the first through hole, and the heating block is just sleeved on the sleeve part through its connecting hole.

[0021] In the above 3D printing device, a feeding funnel is provided at the upper end of the screw sleeve. The feeding funnel is connected to the discharge end of the storage and feeding mechanism. At least one annular heat dissipation fin is axially distributed on the feeding funnel, and / or a funnel cooling fan is provided on the side of the feeding funnel. The funnel cooling fan is fixed on a fixed bracket.

[0022] As an intermediate channel, the feeding funnel ensures the smooth transportation of the raw material channel from the storage and feeding mechanism to the screw sleeve. The heat dissipation fins and the funnel cooling fan can both be used to cool the feeding funnel to prevent the raw material particles from getting hot and sticking in the feeding funnel, which may affect the downward transportation.

[0023] As an optimization, the funnel flange at the lower end of the feed hopper and the sleeve flange at the upper end of the screw sleeve are fixedly connected by bolts, which has flexible detachability. In order to reduce energy loss and prevent the feed hopper from getting too hot, a backup cooling structure is also provided between the sleeve flange and the funnel flange. The backup cooling structure includes an annular cooling ring. The cooling ring is circumferentially distributed with axially extending second through holes, which correspond to the connection holes on the sleeve flange and the funnel flange. The interior of the cooling ring is hollow to form a circulation cavity. An input pipe and an output pipe connected to the circulation cavity are connected to the cooling ring. The input pipe and the output pipe are connected to a heat exchange liquid conveying device. A funnel temperature measuring component is connected to the feed hopper. The heat exchange liquid conveying device is used to stop the circulation of the heat exchange liquid when the temperature of the feed hopper is lower than the preset temperature to reduce the heat consumption of the lower screw sleeve, but when the temperature of the feed hopper is higher than the preset temperature, it circulates the heat exchange liquid to block the heat conduction between the screw sleeve and the feed hopper, realizing rapid cooling of the feed hopper.

[0024] The cooling ring is similar in shape to the flange and can play an intermediate supporting role to ensure a stable connection between the funnel flange and the sleeve flange. A circulation cavity is formed inside it. Of course, the second through holes pass through the circulation cavity but are not connected. Moreover, the through holes of the cooling ring are smoothly docked with the lower opening of the upper feed hopper and the upper port of the screw sleeve to ensure the smooth conveyance of raw material particles. The circulation cavity can circulate the heat exchange liquid, which is used to timely block or reduce the heat conduction efficiency to the feed hopper when the temperature of the feed hopper is too high, realizing the temperature control of the feed hopper and preventing the raw material particles from melting prematurely in the feed hopper. The funnel temperature measuring component and the heat exchange liquid conveying device are prior arts and will not be specifically elaborated here.

[0025] As a further optimization, a stirring structure is provided between the upper end of the feeding screw and the feed hopper. The stirring structure includes at least one stirring rod circumferentially distributed and attached to the conical inner wall of the feed hopper. The stirring rod extends along the length direction of the conical inner wall and is fixedly connected to the smooth rod section at the upper end of the feeding screw through a fixing rod. The end of the fixing rod is fastened to the feeding screw through a hoop structure.

[0026] The stirring rod and the fixing rod are in a Y shape and are fixedly connected to the feeding screw and rotate synchronously. Of course, the inclination angle of the stirring rod is adapted to the conical inner wall of the feed hopper and can move along the conical inner wall of the feed hopper during the printing operation to stir the raw material particles attached to the inner wall, reducing the possibility of the raw material particles in long-term contact with the high-temperature inner wall of the feed hopper from melting prematurely, and also facilitating the feeding of the feed hopper. The hoop structure makes the connection between the fixing rod and the feeding screw have flexible detachability. The specific structure is a prior art and will not be elaborated.

[0027] In the above 3D printing device, at least two groups of end cooling fans are evenly distributed circumferentially outside the nozzle. The end cooling fans are fixed on a fixed bracket and blow air to the end of the nozzle for heat dissipation through a guiding tube. The guiding tube includes a conical air duct, and the width of its air outlet is adapted to the diameter of the nozzle.

[0028] An end cooling fan is provided at the lower end of the screw extrusion mechanism to cool the raw material after it is input into the nozzle for rapid shaping, ensuring the 3D printing forming effect. A guiding tube is connected to the end cooling fan to guide the air to the corresponding position through the conical air duct therein. The conical air duct is gradually narrowing, and its air outlet is the small end, which is adapted to the size of the nozzle, increasing the speed of the air output from the air outlet and improving the heat dissipation efficiency.

[0029] Furthermore, wind guiding protrusions are spirally distributed along the air outlet direction inside the guiding tube to output the air in a spiral rotation manner. On the one hand, it increases the contact with the guiding tube, improving the heat exchange and heat dissipation effect of the guiding tube. On the other hand, the spiral blowing output improves the cooling effect on the raw material output below the nozzle, facilitating the rapid shaping of the molten raw material from multiple angles.

[0030] As an optimization, the printing device includes a protective housing. The screw extrusion mechanism is arranged inside the protective housing. The protective housing also includes a horn-shaped protective cover at the lower end, and the nozzle is located inside the protective cover.

[0031] Another object of the present invention is to propose a printing control method for the above problems existing in the prior art.

[0032] To achieve this object of the present invention for innovation, the following technical solutions can be adopted: A printing control method applicable to the above 3D printing device includes the following steps: S1. Receive a 3D model file through a 3D model layer slicing module, dynamically adjust the slicing parameters based on the rheological properties of the material, and generate a structured control instruction file containing line width (d) and layer height (h) tags. S2. Analyze the printing parameters using a trajectory prediction model to generate a robotic arm joint motion trajectory instruction. The input parameters include printing speed (V) and screw diameter (D), and the output is a trajectory instruction in the form of a Denavit - Hartenberg matrix. S3. Calculate the simulated output value AO according to the point position data file. S4. According to the real - time printing speed (V′), output a compensation coefficient (γ) through a closed - loop control algorithm and calculate the corrected motor speed. The calculation formula is: ; S5. The host computer controls the movement of the robotic arm through the robotic arm control data, and at the same time controls the driving motor of the printing device according to the motor speed data; S6. The displacement detection device is used to collect the nozzle position deviation (Δx), and the real-time printing speed is corrected to, and the calculation formula is: , And input the corrected V′ into step S3 to recalculate the analog output value AO′; S7. Encrypt the process parameter log (including timestamp, material consumption, PID parameters) and upload it to the cloud service platform, which supports SQL-based query and Matplotlib visual analysis.

[0033] The printing control method of the present invention is used to realize the coordinated control of the robotic arm and the printing device. Step S1 is used to convert the model to be printed into a corresponding point position data file, and this file is in Gcode format, while the industrial robot controlling the robotic arm is not compatible with this format. Step S2 is used to convert the original point position data file into the robotic arm control data in the corresponding format; Step S3 calculates the analog output value AO, and the unit of this AO value is volts; Step S4 calculates the corresponding motor speed data through the AO value, and the motor speed data is used to specifically control the rotation of the screw drive motor. Ideally, the range of the AO value is from 0 volts to +10 volts, linearly corresponding to the screw drive motor speed from 0 r / min to 3000 r / min; due to the deviation between the expected situation and the actual situation, step S6 is used to make corresponding corrections according to the actual situation, specifically by correcting the analog output quantity through the real-time actual speed, and then correcting the motor speed data through this output quantity to improve the coordination of the robotic arm and the printing device.

[0034] More specifically, the input layer of the convolutional neural network (CNN) is a 3×100 matrix, which contains the historical data of V, D, and N of nearly 100 printing tasks. The training uses the Adam optimizer, the learning rate is set to 0.001, and the MSE of the test set drops to 0.012 after 500 iterations.

[0035] In step S7, the process parameter log is encrypted and uploaded to the cloud platform. The encryption algorithm uses AES-256 encryption, and the key is stored through the hardware security module (HSM). The encrypted data is transmitted in Base64 encoding. Specifically, the data storage uses the MySQL database, and the log table fields include: timestamp, material_consumption, PID_params (in JSON format); the query interface provides a RESTful API, which supports filtering data by time range and material type.

[0036] In addition, the visual analysis in step S7 generates dynamic charts (such as the extrusion non-uniformity rate trend chart) through Matplotlib and integrates the Jupyter Notebook template for users to customize the analysis.

[0037] Regarding the training process of the neural network compensation coefficient γ, the training data comes from the sensor logs of historical printing tasks, including parameters such as V, D, N, Δx, T (temperature), with a total of 10,000 groups of samples, covering 5 materials (such as ABS, PETG, TPU). When the data is preprocessed, it is normalized to the interval [0, 1], and noise (±2%) is added to enhance the robustness of the model. In the model structure, the input layer is a 5-dimensional vector (V, D, N, Δx, T); the hidden layer is 3 fully connected layers (128 - 64 - 32 nodes), with the activation function being ReLU; the output layer is a single node (γ), with the activation function being Sigmoid (restricting γ ∈ [0.8, 1.2]).

[0038] The compensation coefficient γ satisfies , where K P , K I are the proportional-integral control parameters.

[0039] In the above printing control method, step S1 specifically is: using slicing software to generate the point position data file corresponding to the model, and this point position data file is in Gcode format; Step S2 includes: using the trajectory prediction model to process the point position data file. First, use a For loop to iterate through all the data, then read out the XYZ-axis data of each point position data, and then write the XYZ-axis data of the point position, the pose data during printing, and the movement speed into a set of robotic arm control data.

[0040] Step S2 details the conversion from the point position data file to the robotic arm control data, and the pose data is stored in the robot teach pendant.

[0041] In the above printing control method, step S3 specifically includes: calculating the simulated output value AO of the printing device, and the calculation formula is: where d is the slicing line width (mm), h is the slicing layer height (mm), V is the printing speed (mm / s), D is the diameter of the feeding screw (mm), H3 is the depth of the screw groove of the feeding screw (mm), θ is the thread lead angle of the feeding screw (degrees), and K is the reduction ratio of the reducer.

[0042] In the above printing control method, step S4 specifically includes calculating the driving motor speed N based on the AO value, and the calculation formula is: ; The specific steps of step S6 include correcting AO to AO' and N to N', and the calculation formula is: .

[0043] As an expansion of the formula derivation process, the AO value is determined by formula calculation. Different line widths and layer heights correspond to different material flow rates. When generating the original point data file, the material flow rate can be calculated by substituting the set parameters into the formula. The formula for calculating the material flow rate is as follows: (1) Then substitute the Q value obtained from formula (1) into formula (2) to calculate the corresponding screw drive motor speed. Formula (2) is as follows: (2) Record multiple groups of AO values and the corresponding motor speed N. Substitute these AO values and the corresponding motor speed N into the linear regression formula to obtain the relationship between the AO value and the motor speed N. The conversion formula is as follows: (3) Among them, K1 and K2 are two constants calculated by the linear regression formula, K1 = 0.0034, and K2 = 0.958.

[0044] Compared with the prior art, the present invention mainly has the following advantages: 1. The printing device of this 3D printing equipment is controlled by a robotic arm to move. The printing range is larger, the environmental requirements are lower, and the requirement for the flatness of the bottom plate is also lower. In the printing device, the screw extrusion mechanism specifically heats and softens the raw material particles and extrudes them to the corresponding positions to achieve the purpose of printing. Compared with wire printers, its material selection range is wider, more types of materials can be used, the raw material cost can be effectively reduced, the flow rate can be increased at the same time, and the printing time can be shortened. The upper computer is connected to the robotic arm and the printing device at the same time, and is used to coordinate the movement of the robotic arm and the raw material output of the printing device. Functions such as empty running, real-time flow control, and speed feedback flow control can be realized. At the same time, it is more convenient and fast in model slicing and point processing, and has greater advantages in printing debugging. It can understand the operation of the program more clearly, and it is easier to find and solve problems.

[0045] 2. In order to improve the rate at which raw material particles enter from the feeding port, a pneumatic auxiliary structure is also provided on the storage barrel. High-speed air flows in from the air inlet and out from the air outlet. During the air flow process, the raw material particles are inhaled to improve the feeding rate. The high-speed air can also take away the dust between the raw material particles to improve the 3D printing quality.

[0046] 3. To ensure the smooth transmission of raw material particles in the feed pipe, a vibration motor is connected to the feed pipe to avoid the blockage of raw material particles by vibration.

[0047] 4. A temperature sensor is also connected to the screw sleeve. The temperature sensor is located in the temperature measurement relief hole of the annular heating coil to improve the accuracy of the measured temperature.

[0048] 5. The heat dissipation fins and the funnel cooling fan can both be used to cool the feed funnel, avoiding problems such as adhesion of raw material particles due to heat in the feed funnel, which affect the downward transportation.

[0049] 6. A terminal cooling fan is provided at the lower end of the screw extrusion mechanism to cool the raw material after it is input from the nozzle for rapid shaping, ensuring the 3D printing forming effect. A guide pipe is connected to the terminal cooling fan, and the outlet of the guide pipe is adapted to the size of the nozzle, improving the air outlet rate of the air outlet and enhancing the heat dissipation efficiency.

[0050] 7. Step S1 of this printing control method is used to convert the model to be printed into a corresponding point position data file. Step S2 is used to convert the original point position data file into the robotic arm control data in the corresponding format for controlling the movement of the robotic arm; Step S3 calculates the simulated output value AO value; Step S4 calculates the corresponding motor speed data through the AO value for specifically controlling the rotation of the screw drive motor; Step S6 is used to make corresponding corrections according to the actual situation. Specifically, the simulated output quantity is corrected by the real-time actual speed, and then the motor speed data is corrected by this output quantity to improve the actual coordination of the robotic arm and the printing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is the overall structural schematic diagram of the 3D printing device provided by the present invention; Figure 2 is the overall structural schematic diagram of the printing device provided by the present invention; Figure 3 is the sectional schematic diagram of the printing device provided by the present invention (the air guiding protrusion is not shown); Figure 4 is the structural schematic diagram of the printing device after hiding the protective housing provided by the present invention; Figure 5 is the structural schematic diagram of the feeding screw provided by the present invention; Figure 6 is the structural schematic diagram of the connecting screw head provided by the present invention; Figure 7 is Figure 3 the detailed enlarged view of part A in Figure 8 is the program operation logic diagram of the 3D printing control method provided by the present invention; Figure 9 This is a schematic cross-sectional view of the spare cooling structure and the material stirring structure provided by the present invention.

[0052] In the figure, there are industrial robot 1, robotic arm 11, printing device 2, fixed bracket 21, protective housing 22, protective cover 23, material storage and feeding mechanism 3, material storage barrel 31, vibration motor 32, motor fixing part 33, feeding port 34, feeding pipe 35, screw extrusion mechanism 4, screw sleeve 41, feeding screw 42, screw driving motor 43, nozzle 44, heating structure 45, coupling 46, reducer 47, motor cooling fan 48, annular heating coil 49, temperature measurement relief hole 50, temperature sensor 51, feeding funnel 52, funnel cooling fan 53, funnel flange 54, sleeve flange 55, end cooling fan 56, guiding pipe 57, heating block 58, heat dissipation fins 59, connecting screw head 60, external thread section 61, socket part 62, first through hole 63, hexagonal turning part 64, air guiding protrusion 65, spare cooling structure 7, cooling ring 71, second through hole 72, flow cavity 73, input pipe 74, output pipe 75, material stirring structure 8, stirring rod 81, fixed rod 82, hoop structure 83. Specific embodiments

[0053] The following are specific embodiments of the present invention in combination with the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0054] Embodiment 1 The specific embodiment of this 3D printing device is as Figures 1-7 shown, including a robotic arm 11 controlled by an industrial robot 1. A printing device 2 is provided on the robotic arm 11 through a fixed bracket 21. The industrial robot 1 and the printing device 2 are respectively connected to a host computer. The printing device 2 includes a material storage and feeding mechanism 3 and a screw extrusion mechanism 4. The discharge end of the material storage and feeding mechanism 3 is connected to the feeding end of the screw extrusion mechanism 4.

[0055] Specifically, this 3D printing device mainly consists of a robotic arm 11 and a printing device 2. The printing device 2 is arranged on the robotic arm 11, and the movement of the printing device 2 is controlled by the robotic arm 11. It has a larger printing range, lower environmental requirements, and lower requirements for the flatness of the bottom plate. In the printing device, a material storage and feeding mechanism 3 is used to store raw material particles and convey the raw material particles to a screw extrusion mechanism 4 when needed. The screw extrusion mechanism 4 specifically heats and softens the raw material particles and extrudes them to the corresponding positions to achieve the purpose of printing. Compared with wire printers, screw extruders have a wider range of material selection, can use more types of materials, can effectively reduce raw material costs, and can also increase the flow rate and shorten the printing time. The host computer is connected to the industrial robot 1 and the printing device 2 at the same time, and is used to coordinate the movement of the robotic arm 11 and the raw material output of the printing device 2. Functions such as empty running, real-time flow control, and speed feedback flow control can be achieved. At the same time, it is more convenient and fast in model slicing and point position processing, and has greater advantages during printing debugging. It can more clearly understand the operation of the program, and more easily find and solve problems.

[0056] As Figures 1-4 shown, the material storage and feeding mechanism 3 includes a storage barrel 31. The upper end of the storage barrel 31 is provided with a feeding port 34, and the lower end is connected to the screw extrusion mechanism 4 through a feed pipe 35. The storage barrel 31 is also provided with an air inlet and an air outlet. An air pump assembly is connected to the air inlet, and a filter screen through which raw material particles cannot pass is arranged inside the air outlet. A vibration motor 32 is also connected to the feed pipe 35 through a motor fixing member 33.

[0057] Specifically, the storage barrel 31 is used to store raw material particles. The feeding port 34 at its upper end is used to add raw material particles, and the lower end conveys the raw materials to the screw extrusion mechanism 4 through the feed pipe 35. In order to improve the rate at which raw material particles enter from the feeding port 34, a pneumatic assistance structure is also arranged on the storage barrel 31 to improve the feeding rate. The high-speed air flow can also carry away the dust between the raw material particles, improving the 3D printing quality. In order to ensure the smooth transmission of raw material particles in the feed pipe 35, a vibration motor 32 is connected to the feed pipe 35 to avoid the blockage of raw material particles by vibrating. The motor fixing member 33 is clamped on the feed pipe 35 by a set of semi-circular hoop plates and fixed by bolts, with flexible detachability.

[0058] As Figures 3-5As shown, the screw extrusion mechanism 4 includes a screw sleeve 41 and a feed screw 42 rotatably connected to the screw sleeve 41. The upper end of the feed screw 42 is connected to the screw drive motor 43 through a reducer 47. The upper end of the screw sleeve 41 is connected to the discharge end, and the lower end is connected to a nozzle 44. A heating structure 45 is provided between the screw sleeve 41 and the nozzle 44. The upper end of the feed screw 42 is connected to the reducer 47 through a coupling 46, and the reducer 47 is connected to the screw drive motor 43. A motor cooling fan 48 is provided on the side of the screw drive motor 43, and the motor cooling fan 48 is fixed to the fixed bracket 21. The heating structure 45 includes four annular heating rings 49 axially distributed on the outer wall of the screw sleeve 41, and a heating block 58 arranged on the nozzle 44. The annular heating rings 49 are provided with temperature measuring holes 50. The temperature measuring holes 50 are provided with temperature sensors 51 connected to the outer wall of the screw sleeve 41. Temperature sensors 51 are also provided between the annular heating rings 49.

[0059] Specifically, a feeding screw 42 having an outer diameter adapted to the inner diameter is inserted into the screw sleeve 41, and a screw drive motor 43 is used to drive the rotation of the feeding screw 42. The raw material particles are input into the upper end of the screw sleeve 41, and are extruded and transported to the lower end under the rotation of the feeding screw 42. The heating structure 45 is used to soften the raw material particles to ensure that the lower end nozzle 44 outputs molten raw materials. The feeding screw 42 is connected to the output end of the screw drive motor 43 through a coupling 46 and a reducer 47. The motor cooling fan 48 is used to blow air to dissipate heat from the screw drive motor 43 to prevent the motor from overheating and being damaged. The heating structure 45 is specifically realized by an annular heating ring 49 circumferentially arranged on the screw sleeve 41. The annular heating ring 49 is a ceramic heating ring, which is used to heat the screw sleeve 41, thereby achieving the effect of softening the raw material particles. Moreover, it is detachably fixed to the heating block 58 on the nozzle 44 through a connecting screw head 60. The heating block 58 can be made of a brass heating block with good thermal conductivity, thereby ensuring that the raw material is in a good molten state when it is output from the nozzle 44. In addition, a temperature sensor 51 is also connected to the screw sleeve 41 for detecting the sleeve temperature, thereby achieving the effect of accurately controlling the temperature. The temperature sensor 51 is located in the temperature measuring hole 50 of the annular heating ring 49 to improve the accuracy of the measured temperature.

[0060] In this embodiment, the heating block 58 is square and has a connecting hole vertically penetrated in the axial direction. The upper part of the connecting screw head 60 is provided with an external thread section 61 adapted to the internal thread of the lower end of the screw sleeve 41, and the lower part is provided with a sleeve portion 62 adapted to the inner diameter of the connecting hole, and a first through hole 63 is axially penetrated. The lower end of the first through hole 63 is provided with an internal thread adapted to the external thread of the nozzle 44, and a hexagonal screwing portion 64 is provided between the sleeve portion 62 and the external thread section 61. The external thread section 61 is screwed to the lower end of the screw sleeve 41, and the nozzle 44 is screwed to the lower end of the first through hole 63. The heating block 58 is just sleeved on the sleeve portion 62 through its connecting hole.

[0061] As Figure 2 , Figure 3 , Figure 4 shown, a feed hopper 52 is provided at the upper end of the screw sleeve 41. The feed hopper 52 is connected to the discharge end of the storage and feeding mechanism 3. Nine annular heat dissipation fins 59 are axially distributed on the feed hopper 52. A hopper heat dissipation fan 53 is provided on the side of the feed hopper 52. The hopper heat dissipation fan 53 is fixed on the fixed bracket 21.

[0062] Specifically, the feed hopper 52 serves as an intermediate channel to ensure the smooth transportation of the raw material channel from the storage and feeding mechanism 3 to the screw sleeve 41. Both the heat dissipation fins 59 and the hopper heat dissipation fan 53 can be used to cool the feed hopper 52, avoiding problems such as the adhesion of raw material particles due to heat in the feed hopper 52, which affects the downward transportation. The hopper flange 54 at the lower end of the feed hopper 52 and the sleeve flange 55 at the upper end of the screw sleeve 41 are fixedly connected by bolts, having flexible detachability.

[0063] As Figure 3 , Figure 7 shown, two groups of end heat dissipation fans 56 are evenly distributed circumferentially on the outer periphery of the nozzle 44. The end heat dissipation fans 56 are fixed on the fixed bracket 21 and blow air to the end of the nozzle 44 for heat dissipation through the guide pipe 57. The guide pipe 57 includes a conical air duct, and the width of its air outlet is adapted to the diameter of the nozzle 44. A spiral air guiding protrusion 65 is provided in the guide pipe 57.

[0064] Specifically, an end heat dissipation fan 56 is provided at the lower end of the screw extrusion mechanism 4 to cool the raw material after it is input into the nozzle 44 for rapid shaping, ensuring the 3D printing forming effect. The end heat dissipation fan 56 is connected with a guide pipe 57 to guide the air to the corresponding position through the conical air duct therein. The conical air duct is gradually narrowing, and its air outlet is the small end, which is adapted to the size of the nozzle 44, improving the air output speed of the air outlet and the heat dissipation efficiency. The air guiding protrusion 65 outputs the air in a rotating manner, improving the heat dissipation effect.

[0065] In this embodiment, the screw extrusion mechanism 4 is arranged in the protective housing 22. A horn-shaped protective cover 23 is provided at the lower end of the protective housing 22. The nozzle 44 is located in the protective cover 23.

[0066] On the other hand, this embodiment also provides a 3D printing control method, and the following formulas are used in this method: (1) (2) (3) (4) The specific printing process is as follows: 1. Load the model to be printed (STL type file) into the open-source slicing software Cura, set the slicing layer height to 2.5 mm, the slicing line width to 3 mm, and the printing speed to 100 mm / s, and then perform the slicing operation on the model; 2. Substitute the layer height, line width, and printing speed set for the sliced model into formula (1) to calculate and obtain .

[0067] 3. Substitute the Q value into formula (2) to calculate and obtain = 1581.954 r / min.

[0068] 4. Set different AO values, and then record the corresponding motor speeds for each AO value to obtain the following data set: 5. Substitute the data set obtained in the previous step into the linear regression equation to calculate and obtain formula (3) , where is the coefficient of determination, which is a parameter used to measure the goodness of fit of the model in linear regression calculations. The value ranges from 0 to 1, and the closer it is to 1.0, the better the fitting situation. Since in this embodiment , it indicates that the fitting situation of this formula is very good. Therefore, formula (3) can be used to calculate the AO value and the motor speed N. , indicating that the fitting situation of this formula is very good. Therefore, formula (3) can be used to calculate the AO value and the motor speed N.

[0069] 6. Substitute the motor speed N value obtained in the third step into formula (3) obtained in the fifth step to get: 7. After setting the variable AO_SET for storing the AO value in the robot program to 5.47, printing can start.

[0070] During the printing process, the "Read" program in the industrial robot will read the real-time speed of the robot while controlling the movement, compare the real-time speed with the preset speed, then calculate the proportional relationship between the real-time speed and the preset speed, and then calculate the flow rate that should be set at present through formula (4), and send this variable to the "Speed_Read" program to modify the AO value.

[0071] Assuming that the real-time speed read is 150 mm / s, then according to formula (4), we can get Wherein, is the analog output value (volt) after feedback control, and V’ is the actual printing speed (mm / s).

[0072] After the printing work is completed, the screw drive motor stops running, the industrial robot runs back to the Home point, and then the host computer program and the industrial robot program end running one after another.

[0073] Embodiment 2 The specific working principle of this embodiment is basically the same as that of Embodiment 1, and the difference lies in the spare cooling structure 7 and the stirring structure 8.

[0074] Specific embodiments are as Figure 9 shown. In order to reduce energy consumption and prevent the temperature of the feed hopper 52 from being too high, a spare cooling structure 7 is also provided between the sleeve flange 55 and the hopper flange 54. The spare cooling structure 7 includes an annular cooling ring 71. The cooling ring 71 is circumferentially distributed with axially extending second through holes 72, and the through holes correspond to the connection holes on the sleeve flange 55 and the hopper flange 54. The inside of the cooling ring 71 is hollow to form a circulation cavity 73. An input pipe 74 and an output pipe 75 communicating with the circulation cavity 73 are connected to the cooling ring 71. The input pipe 74 and the output pipe 75 are connected to the heat exchange liquid conveying device. A hopper temperature measuring component is connected to the feed hopper 52. The heat exchange liquid conveying device is used to stop the circulation of the heat exchange liquid when the temperature of the feed hopper 52 is lower than the preset temperature, so as to reduce the heat consumption of the lower screw sleeve 41, but when the temperature of the feed hopper 52 is higher than the preset temperature, the heat exchange liquid circulates, reducing and even blocking the heat conduction between the screw sleeve 41 and the feed hopper 52, and realizing the rapid cooling of the feed hopper 52.

[0075] Specifically, the cooling ring 71 is similar in shape to the flange, which can play an intermediate supporting role to ensure the stable connection between the hopper flange 54 and the sleeve flange 55. A circulation cavity 73 is formed inside it. Of course, the second through hole 72 passes through the circulation cavity 73 but is not connected. The circulation cavity 73 can circulate the heat exchange liquid, which is used to block or reduce the heat conduction efficiency of the feed hopper 52 in time when the temperature of the feed hopper 52 is too high, realize the temperature control of the feed hopper 52, and avoid the premature melting of the raw material particles in the feed hopper 52.

[0076] Furthermore, a stirring structure 8 is provided between the upper end of the feeding screw 42 and the feed hopper 52. The stirring structure 8 includes a stirring rod 81 that is attached to the conical inner wall of the feed hopper 52. The stirring rod 81 extends along the length direction of the conical inner wall and is fixedly connected to the polished rod section at the upper end of the feeding screw 42 through a fixing rod 82. The end of the fixing rod 82 is clamped to the feeding screw 42 through a hoop structure 83.

[0077] Specifically, the stirring rod 81 and the fixed rod 82 are in a y-shaped configuration, which are fixedly connected to the feeding screw 42 and rotate synchronously. Of course, the inclination angle of the stirring rod 81 is adapted to the conical inner wall of the feeding funnel 52, and it can move along the conical inner wall of the feeding funnel 52 during the printing operation to agitate the raw material particles adhering to the inner wall, reducing the possibility of premature melting of the raw material particles in long-term contact with the high-temperature inner wall of the feeding funnel, and also facilitating the feeding.

[0078] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A 3D printing device, characterized in that, It includes a robotic arm (11) controlled by an industrial robot (1). A printing device (2) is arranged on the robotic arm (11) through a fixed bracket (21). The industrial robot (1) and the printing device (2) are respectively connected to a host computer. The printing device (2) includes a material storage and feeding mechanism (3) and a screw extrusion mechanism (4). The discharging end of the material storage and feeding mechanism (3) is connected to the feeding end of the screw extrusion mechanism (4). The host computer includes: A three-dimensional model layer slicing module: It is used to generate layer slicing data from the input three-dimensional model data through a mesh division algorithm. The layer slicing data includes the slice layer height (h) and the filling density parameter, and is transmitted to the path planning module through a structured data transmission protocol. A path planning module: Based on the layer slicing data, it generates the motion trajectory of the robotic arm, and uses a parametric curve interpolation algorithm to smooth the trajectory. The optimized trajectory data is transmitted to the robotic arm controller in real time through an industrial communication protocol. A dynamic cooperative control module: It monitors the deviation between the printing speed (V′) and the target speed (V) in real time, and corrects the rotation speed (N) of the screw driving motor through a proportional-integral control algorithm. The calculation formula is: ， Among them, and are PID control parameters; Feedback compensation module: The displacement detection device set at the printing nozzle is used to collect the position deviation Δx at the end of the nozzle in real time, and generate a speed correction signal to synchronously adjust the motion trajectory of the robotic arm. The speed correction signal satisfies , where is the dynamic compensation parameter.

2. The 3D printing device according to claim 1, characterized in that, The material storage and feeding mechanism (3) includes a material storage barrel (31). A feeding port (34) is arranged at the upper end of the material storage barrel (31), and the lower end is connected to the screw extrusion mechanism (4) through a feeding pipe (35). An air inlet and an air outlet are also arranged on the material storage barrel (31). An air pump assembly is connected to the air inlet. A filter screen through which raw material particles cannot pass is arranged inside the air outlet. A vibration motor (32) is also connected to the feeding pipe (35) through a motor fixing piece (33).

3. The 3D printing device according to claim 1, characterized in that, The screw extrusion mechanism (4) includes a screw sleeve (41) and a feeding screw (42) rotatably connected inside the screw sleeve (41). The upper end of the feeding screw (42) is connected to a screw driving motor (43) through a reducer (47). The upper end of the screw sleeve (41) is connected to the discharging end, and the lower end is connected to a nozzle (44). A heating structure (45) is arranged between the screw sleeve (41) and the nozzle (44).

4. The 3D printing device according to claim 3, characterized in that, The heating structure (45) includes at least one annular heating coil (49) axially distributed on the outer wall of the screw sleeve (41), and a heating block (58) detachably fixed to the nozzle (44) through a connecting screw head (60). A temperature measurement relief hole (50) is opened on the annular heating coil (49). A temperature sensor (51) connected to the outer wall of the screw sleeve is arranged in the temperature measurement relief hole (50), and / or a temperature sensor (51) is arranged between the annular heating coils (49).

5. The 3D printing device according to claim 3, characterized in that, The upper end of the screw sleeve (41) is provided with a feed hopper (52), and the feed hopper (52) is connected to the discharge end of the storage and feeding mechanism (3). At least one annular heat dissipation fin (59) is axially distributed on the feed hopper (52), and / or a funnel heat dissipation fan (53) is provided on the side of the feed hopper (52). The funnel heat dissipation fan (53) is fixed on the fixed bracket (21).

6. The 3D printing device according to claim 3, characterized in that, At least two groups of end heat dissipation fans (56) are evenly distributed circumferentially outside the nozzle (44). The end heat dissipation fans (56) are fixed on the fixed bracket (21), and blow air to dissipate heat from the end of the nozzle (44) through the guide pipe (57). The guide pipe (57) includes a conical air duct, and the width of its air outlet is adapted to the diameter of the nozzle (44).

7. A printing control method, characterized in that, The 3D printing device applicable to any one of claims 1-6 includes the following steps: S1. Receive a 3D model file through a three-dimensional model layer slicing module, dynamically adjust the slicing parameters based on the material rheological properties, and generate a structured control instruction file containing line width (d) and layer height (h) tags. S2. Analyze the printing parameters using a trajectory prediction model to generate a robotic arm joint motion trajectory instruction. The input parameters include the printing speed (V) and the screw diameter (D), and the output is a trajectory instruction in the form of a Denavit-Hartenberg matrix. S3. Calculate the simulated output value AO according to the point position data file. S4. According to the real-time printing speed (V′), output a compensation coefficient (γ) through a closed-loop control algorithm, and calculate the corrected motor speed. The calculation formula is: , where N is the motor speed before correction; S5. The host computer controls the motion of the robotic arm through the robotic arm control data, and at the same time controls the driving motor of the printing device according to the motor speed data. S6. Collect the nozzle position deviation (Δx) through a displacement detection device, and correct the real-time printing speed to, and the calculation formula is: ， And input the corrected V′ into step S3 to recalculate the simulated output value AO′. S7. Encrypt the process parameter log and upload it to the cloud service platform, which supports SQL-based query and Matplotlib visualization analysis. The process parameter log includes one or more data such as timestamp, material consumption, and PID parameters.

8. The printing control method according to claim 7, characterized in that, The specific step S1 is: use slicing software to generate a point position data file corresponding to the model, and this point position data file is in Gcode format. The step S2 includes: using a trajectory prediction model to process the point position data file. First, use a For loop to iterate through all the data, then read out the XYZ axis data of each point position data, and then write the XYZ axis data and the motion speed of the point position as a set of robotic arm control data.

9. The printing control method according to claim 7, characterized in that, The specific step S3 includes: calculating the simulated output value AO (volt) of the printing device, and the calculation formula is: ， Where d is the slicing line width (mm), h is the slicing layer height (mm), V is the printing speed (mm / s), D is the diameter of the feeding screw (mm), H3 is the depth of the screw groove of the feeding screw (mm), θ is the thread lead angle of the feeding screw (degree), and K is the reduction ratio of the reducer.

10. The printing control method according to claim 9, characterized in that, The specific steps of step S4 include calculating the driving motor speed N (r / min) according to the AO value, and the calculation formula is: ； The specific steps of step S6 include correcting AO to AO' and correcting N to N', and the calculation formula is: ， ， Wherein, AO' is the corrected analog output value (volt), V' is the real-time printing speed (mm / s), and N' is the corrected driving motor speed (r / min).

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