A 3D printing head and additive manufacturing equipment with automatic positioning and replacement function

Abstract

This invention discloses a 3D printing head and additive manufacturing equipment with automatic positioning and replacement function, belonging to the field of additive manufacturing technology. It includes a support frame, a moving mechanism, a mounting base, a vision positioning camera, a printing head body, a second moving component, a replacement mechanism, and control components. The replacement mechanism includes a robotic arm and a placement box containing multiple spare printing heads. The control components are configured to: monitor the printing head's working status in real time and automatically trigger a replacement request; control the moving mechanism for coarse positioning; activate the vision positioning camera to acquire images and calculate compensation for fine positioning; control the robotic arm to disassemble the old printing head and install a new printing head; and resume printing operation after verifying the new printing head is functioning correctly. This invention achieves fully automatic closed-loop replacement and resume printing from interrupted points through status monitoring, vision-guided fine positioning, and robotic arm-assisted replacement, eliminating the need for manual intervention and improving the continuous operation capability and automation level of additive manufacturing equipment.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, specifically to a 3D printing head and additive manufacturing equipment with automatic positioning and replacement function. Background Technology

[0002] In additive manufacturing (3D printing) technology, the print head (extrusion unit) is a key component. During prolonged continuous printing or printing of high-strength / high-melting-point materials, the print head is prone to failure due to factors such as heating rod aging, thermocouple failure, nozzle clogging, or extrusion motor overload, leading to printing interruptions. Furthermore, the print head needs to be replaced when switching between nozzles of different diameters or different materials (such as switching from PLA to ABS).

[0003] Most existing 3D printing equipment uses manual printhead replacement. Operators need to stop the machine and manually unscrew the fixing screws, plug and unplug the cables, reinstall and calibrate. The whole process is time-consuming and requires manual intervention, making it impossible to achieve unattended continuous production. Some high-end equipment provides semi-automatic replacement solutions, such as mechanical quick-change through quick connectors, but still requires manual confirmation and assistance, and lacks the ability to automatically monitor the printhead status and automatically verify the replacement.

[0004] Therefore, developing a device that can automatically monitor the printhead status, autonomously complete replacement operations, and resume printing is of great significance for improving the production efficiency and automation level of additive manufacturing. Summary of the Invention

[0005] This invention provides a 3D print head and additive manufacturing equipment with automatic positioning and replacement function, including a support frame, a moving mechanism, a mounting base, a vision positioning camera, a print head body, a second moving component, a replacement mechanism, and a control unit. The replacement mechanism includes a robotic arm and a placement box containing multiple spare print heads. The control unit is configured to: monitor the print head's working status in real time and automatically trigger a replacement request; control the moving mechanism for coarse positioning; activate the vision positioning camera to acquire images and calculate compensation for fine positioning; control the robotic arm to disassemble the old print head and install a new print head; and resume printing operation after verifying that the new print head is functioning correctly. This invention achieves fully automatic closed-loop replacement and resume printing from interrupted points through status monitoring, vision-guided fine positioning, and robotic arm-assisted replacement, without manual intervention. This improves the continuous operation capability and automation level of additive manufacturing equipment and solves the problems mentioned in the background art.

[0006] The present invention provides the following technical solution: a 3D printing head and additive manufacturing equipment with automatic positioning and replacement function, including a support frame, a moving mechanism provided on the top of the support frame, the moving mechanism including a lifting component installed on the top of the support frame, a first moving component integrated in the lifting component, and a moving plate installed in the first moving component, a mounting base fixedly installed on the outer wall of the moving plate, a visual positioning camera and a 3D printing head body installed at the bottom of the mounting base, a second moving component also provided on the top of the support frame, a base plate installed on the top of the second moving component, a replacement mechanism provided on the top of the base plate, the replacement mechanism including a robotic arm and a placement box fixedly installed on the top of the base plate, and multiple spare printing heads embedded in the placement box, and a control component fixedly installed on the top of the support frame;

[0007] The control element is configured to:

[0008] (a) Monitor the working status parameters of the printhead body in real time, and automatically generate a replacement request when the working status parameters exceed a preset threshold;

[0009] (b) In response to the replacement request, control the moving mechanism to move the printhead body to the coarse positioning coordinates, and control the second moving component to move the replacement mechanism to the corresponding receiving coordinates;

[0010] (c) Start the visual positioning camera to acquire images including the end of the robotic arm and the spare print head, calculate the compensation displacement through image processing, and control the moving mechanism and / or the second moving component to perform fine positioning adjustment according to the compensation displacement;

[0011] (d) After the precision positioning is completed, the robotic arm is controlled to remove the printhead body from the mounting base and place it into the placement box, and then a spare printhead is picked up from the placement box and installed onto the mounting base;

[0012] (e) After verifying that the newly installed printhead is working properly, control the moving mechanism to move the new printhead to the printing interruption point to resume the additive manufacturing operation.

[0013] In a preferred embodiment, the control unit includes a motion control module, a vision positioning and processing module, a robotic arm collaborative control module, a printhead status monitoring module, a decision-making and logic scheduling module, a human-machine interaction module, and a data storage and self-testing module; the motion control module is electrically connected to the lifting assembly, the first moving assembly, and the second moving assembly; the vision positioning and processing module is electrically connected to the vision positioning camera; the robotic arm collaborative control module is communicatively connected to the controller of the robotic arm; the printhead status monitoring module is electrically connected to the sensors and storage chips in the printhead body and the spare printhead; and the decision-making and logic scheduling module is connected to the other modules via an internal message bus.

[0014] In a preferred embodiment, the printhead status monitoring module includes a temperature acquisition unit, a current acquisition unit, a timing and counting unit, and an in-situ detection unit. The temperature acquisition unit is used to read temperature sensor data from the printhead body and the spare printhead in real time. The current acquisition unit is used to monitor the drive current of the extrusion motor. The timing and counting unit is used to accumulate the total power-on time of the printhead body or the length of the extruded filament. The in-situ detection unit is used to detect the placement status of each spare printhead in the placement box and read its identification. When abnormal temperature, excessive current, accumulated usage time exceeding a preset lifespan threshold, or a manual replacement signal is received, the printhead status monitoring module sends a replacement request to the decision and logic scheduling module.

[0015] In a preferred embodiment, the decision and logic scheduling module has a built-in finite state machine, which includes at least an initialization state, a printing operation state, a replacement preparation state, a replacement execution state, a replacement verification state, a print resumption state, and a fault handling state. When a replacement request is received from the printhead status monitoring module, the decision and logic scheduling module controls the printing to be interrupted and saves the current print breakpoint data. It then sequentially drives the motion control module to perform coarse positioning, the vision positioning and processing module to perform fine positioning, the robotic arm collaborative control module to perform disassembly and installation, and the printhead status monitoring module to perform post-replacement verification. After successful verification, the motion control module resumes the printing job. If any sub-step fails, the system enters the fault handling state and issues an alarm.

[0016] In a preferred embodiment, the visual positioning and processing module is configured with hand-eye calibration parameters and a target detection algorithm. During the fine positioning process, the visual positioning and processing module controls the visual positioning camera to acquire images including the end gripper of the robotic arm and the spare print head, identifies the center coordinates and rotation angle of the gripper center and the gripping part of the print head, calculates the compensation displacement (Δx, Δy, Δθ) through the coordinate transformation matrix, and sends it to the motion control module.

[0017] In a preferred embodiment, the robotic arm collaborative control module integrates a force-position hybrid control function; when installing a spare printhead, the robotic arm collaborative control module sends a force control mode command to the robotic arm to push the spare printhead into the mounting base with a preset target force until the contact sensor on the mounting base is triggered, and then controls the automatic locking mechanism to lock it; when disassembling the printhead body, the robotic arm collaborative control module controls the robotic arm to grasp the printhead with a force feedback threshold, and moves it into the placement box after unlocking.

[0018] In a preferred embodiment, the data storage and self-test module includes a non-volatile memory for storing system calibration parameters, replacement history logs, life counters for each printhead, and breakpoint data. When the device is powered on, the data storage and self-test module executes a self-test program to check the communication status of the motion control module, the vision positioning camera, the robotic arm, and the integrity of the calibration matrix. Printing is only allowed to start after the self-test is passed.

[0019] In a preferred embodiment, the placement box has multiple independent slots. Each slot has an in-situ sensor installed at the bottom to detect the in-situ status of the spare printhead. Each slot also has a spring probe on its side that contacts the built-in storage chip of the spare printhead to read the model, parameters, and cumulative usage data of the spare printhead.

[0020] In a preferred embodiment, the lifting assembly is a screw lifting mechanism, and both the first moving assembly and the second moving assembly are synchronous belt linear modules; the moving direction of the first moving assembly and the moving direction of the second moving assembly are perpendicular to each other in the horizontal plane.

[0021] In a preferred embodiment, the control unit is also connected to an emergency stop button and a touch-screen human-machine interface; the emergency stop button has the highest priority and can interrupt all actions of the motion control module and the robotic arm collaborative control module and cut off the drive power; the touch-screen human-machine interface is used to display the current printhead temperature, remaining life, spare printhead list and fault alarm information, and to receive manual replacement, reset and zeroing operation commands.

[0022] The present invention has the following beneficial effects:

[0023] 1. Fully automated closed-loop replacement: Through integrated status monitoring, visual positioning, robotic arm collaboration, and breakpoint resume printing functions, a fully automated process is achieved from fault / lifespan triggering to replacement completion and resumption of printing, without manual intervention, which greatly improves the continuous operation capability of additive manufacturing.

[0024] 2. High-precision positioning and reliable installation: The two-level strategy of "coarse positioning + visual fine positioning" is adopted, combined with the force-position hybrid control installation method, which ensures the repeatability of positioning accuracy during replacement and the reliability of interface connection, avoiding collisions or poor contact caused by positioning deviation.

[0025] 3. Intelligent status management: Each printhead has a built-in storage chip, and the device can automatically record its cumulative usage time, fault history, etc., to achieve predictive maintenance; at the same time, the in-situ detection function of the placement box ensures the availability of spare printheads.

[0026] 4. Modular control architecture: The control components adopt a modular design, with each functional module being independent yet collaborative, facilitating debugging, maintenance, and upgrades, and also enhancing the equipment's compatibility with different brands of robotic arms or vision cameras. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the moving mechanism of the present invention;

[0029] Figure 3 This is a schematic diagram of the replacement mechanism of the present invention;

[0030] Figure 4 This is a schematic diagram showing the position of the control component of the present invention;

[0031] Figure 5 This is a schematic diagram of the control module composition of the present invention;

[0032] Figure 6 The finite state machine diagram for the replacement process of this invention;

[0033] In the diagram: 1. Support frame; 2. Moving mechanism; 21. Lifting assembly; 22. First moving assembly; 23. Moving plate; 3. Mounting base; 4. Visual positioning camera; 5. Printhead body; 6. Second moving assembly; 7. Base plate; 8. Changing mechanism; 81. Robotic arm; 82. Placement box; 83. Spare printhead; 9. Control components. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The 3D printing head and additive manufacturing equipment with automatic positioning and replacement function involved in the present invention are not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figures 1-4The diagram illustrates a 3D printing head and additive manufacturing equipment with automatic positioning and replacement function. It includes a support frame 1 for providing an overall mounting support base. A moving mechanism 2 is mounted on the top of the support frame 1, driving the printing head to move in multiple directions within space. The moving mechanism 2 includes a lifting assembly 21 mounted on the top of the support frame 1, a first moving assembly 22 integrated within the lifting assembly 21, and a moving plate 23 mounted within the first moving assembly 22. The lifting assembly 21 employs a screw-driven structure to drive subsequent components to move vertically. The first moving assembly 22 employs a belt-driven structure to drive the moving plate 23 to move horizontally. A mounting base 3 is fixedly mounted on the outer wall of the moving plate 23 to provide a mounting base. A vision positioning camera 4 and a printing head body 5 are mounted on the bottom of the mounting base 3. 4 is used for visual recognition and positioning of the workpiece position on the printing platform. The print head body 5 is used to perform additive manufacturing printing operations. The top of the support frame 1 is also provided with a second moving component 6. The second moving component 6 adopts a belt drive structure to drive the base plate 7 to move in the second horizontal direction. The base plate 7 is installed on the top of the second moving component 6. The top of the base plate 7 is provided with a replacement mechanism 8 for automatically replacing the print head body 5. The replacement mechanism 8 includes a robotic arm 81 and a placement box 82 fixedly installed on the top of the base plate 7, and multiple spare print heads 83 embedded in the placement box 82. The robotic arm 81 is used to grasp and replace the print head body 5. The placement box 82 is used to store the spare print heads 83 for the robotic arm 81 to use, so as to ensure continuous printing operations. The top of the support frame 1 is also fixedly installed with a control component 9 for controlling the coordinated operation of each component.

[0036] During operation, the operator controls the moving mechanism 2 via the control component 9 to move the print head body 5 to the printing area for additive manufacturing printing. When the print head needs to be replaced, the control component 9 controls the lifting component 21 and the first moving component 22 to move the print head body 5 to the designated replacement position. Then, the control component 9 controls the second moving component 6 to drive the base plate 7 to move, moving the replacement mechanism 8 below the location of the print head body 5. The vision positioning camera 4 performs visual recognition and positioning. Then, the control component 9 controls the robotic arm 81 to remove the print head body 5 and place it into the placement box 82. The spare print head 83 is then picked up from the placement box 82 and installed at the bottom of the mounting base 3. After the automatic positioning and replacement of the print head is completed, the second moving component 6 drives the replacement mechanism 8 to reset. The lifting component 21 and the first moving component 22 drive the replaced print head body 5 back to the printing area to continue the printing operation, thereby realizing the automatic positioning and replacement of the 3D print head and continuous additive manufacturing operation.

[0037] It should be further explained that, in the preferred embodiment of the present invention, the detailed implementation of the control element 9 is as follows:

[0038] I. Hardware Configuration and System Environment of Control Components

[0039] The controller 9 employs an embedded industrial computer equipped with an ARM Cortex-A series multi-core processor with a main frequency of no less than 1.5GHz, 4GB of memory, 64GB of built-in eMMC flash memory for program storage, and an additional 2MB of non-volatile ferroelectric memory (FRAM) for power-off data retention of critical data. The controller runs a real-time operating system (RT-Linux, kernel version 5.10, configured with the PREEMPT_RT real-time patch), with a task scheduling cycle of 1 millisecond. The controller connects to the servo driver via an EtherCAT master protocol stack (such as SOEM or IgH), to the visual positioning camera 4 via the GigE Vision protocol, to the controller of the robotic arm 81 via the Modbus-TCP protocol, and to the EEPROM built into each printhead and the sensors in the placement box 82 via a single-bus protocol.

[0040] The control unit 9 is internally divided into seven modules according to function, such as Figure 5 As shown, the modules communicate with each other via a zero-copy message queue based on shared memory. The seven modules are: motion control module, vision positioning and processing module, robotic arm collaborative control module, print head status monitoring module, decision-making and logic scheduling module, human-machine interaction module, and data storage and self-test module. The connection relationships between the modules are as follows:

[0041] The motion control module is connected to the servo drives of the lifting assembly 21, the first moving assembly 22, and the second moving assembly 6 via an EtherCAT bus. Internally, this module maintains an array of axis objects (Z-axis, X-axis, Y-axis), each encapsulating position, velocity, acceleration, PID parameters, and encoder feedback values. The motion control module is responsible for performing coarse positioning movements, receiving compensation from the vision module for fine adjustments, and restoring the trajectory interpolation used during printing.

[0042] The visual positioning and processing module is connected to the visual positioning camera 4 via a Gigabit Ethernet interface (GigE Vision protocol). This module has built-in hand-eye calibration parameters and image processing algorithms, and is responsible for acquiring images, extracting features, and calculating compensation displacement.

[0043] The robotic arm collaborative control module connects to the controller of robotic arm 81 via the TCP / IP protocol (Modbus-TCP). This module encapsulates the inverse kinematics solution library and force-position hybrid control commands, and is responsible for sending action sequences such as grasping, moving, releasing, and installing.

[0044] The printhead status monitoring module is connected to multiple EEPROMs and sensors (temperature sensor, current sampling circuit, and presence sensor) within the mounting base 3 and placement box 82 via a single-wire interface. This module polls each sensor in a time-division multiplexing manner to monitor the printhead's operating status in real time.

[0045] Furthermore, an in-situ sensor refers to any non-contact or contact sensing element capable of detecting whether the spare printhead 83 has been inserted into the slot. Specifically, it can be:

[0046] Microswitch: A normally open microswitch is used, with the switch contact protruding from the bottom surface of the slot. When the spare printhead 83 is placed in the slot, its bottom plane presses down on the contact, closing the switch, and the control unit 9 detects a low-level signal; when the printhead is removed, the contact resets, the switch opens, and the signal becomes high-level. This method is simple in structure, low in cost, requires no external power supply, and is suitable for environments with low vibration.

[0047] Photoelectric sensor: A reflective photoelectric sensor (such as the ITR series) is used. The sensor includes an infrared emitting tube and a receiving tube, which are installed on the side wall of the slot. When there is no printhead in the slot, the emitted infrared light is reflected by the bottom of the slot, and the receiving tube detects a strong signal. When the printhead is inserted, the printhead shell blocks the light, and the reflected signal is significantly weakened. The control unit 9 determines the presence status by comparing the detected voltage with a preset threshold (e.g., 2.5V). The photoelectric sensor has no mechanical contact, a long lifespan, and a fast response speed (microsecond level), making it suitable for environments with frequent replacements or low dust levels.

[0048] The decision-making and logic scheduling module does not connect directly to external devices, but exchanges instructions and statuses with the other six modules via a message bus. Internally, this module runs a finite state machine engine that manages the complete logic of the changeover process.

[0049] The human-machine interface module connects to a 10.1-inch industrial-grade capacitive touchscreen via an LVDS interface to display device status and receive manual commands.

[0050] The data storage and self-test module connects to FRAM and eMMC via the SPI interface. It is responsible for storing calibration parameters, replacement logs, lifetime counters and breakpoint data, and performs a self-test upon power-up.

[0051] II. Coordinate System Calibration and Transformation Matrix Calculation

[0052] To achieve precise coordinate transformation between the visual positioning camera 4 and the mobile device (mobile mechanism 2 and second mobile component 6) and the robotic arm 81, the control unit 9 performs a calibration process after the equipment is first installed or maintained, and stores the calibration parameters in the data storage and self-test module.

[0053] (a) Camera intrinsic parameter calibration

[0054] The Zhang Zhengyou calibration method is adopted. Control unit 9 controls robotic arm 81 to grasp a chessboard calibration board of known size (square side length 10mm, accuracy ±0.001mm), and sequentially moves the calibration board to nine different positions within the field of view of visual positioning camera 4 (covering the four corners, center, and midpoint of the edge of the field of view). At each position, visual positioning camera 4 captures an image, and control unit 9 runs the findChessboardCorners function from the OpenCV library to extract the sub-pixel coordinates of the corner points. Then, the calibrateCamera function is used to calculate the camera intrinsic parameter matrix K and distortion coefficients D. The intrinsic parameter matrix is ​​in the following form:

[0055] K=[[f x ,0,c x ],[0,f y ,c y ],[0,0,1]]

[0056] Among them, f x f y c is the focal length in pixels. x c y The coordinates are those of the optical center. The distortion coefficients D include radial distortions k1, k2, and k3, and tangential distortions p1 and p2. After calibration, control unit 9 first performs distortion correction on all subsequently acquired images.

[0057] (ii) Hand-eye calibration (transformation between camera and robotic arm)

[0058] The system employs an "eye-outside-hand" configuration (the camera is fixedly mounted at the bottom of mounting base 3, moving with the print head but remaining stationary relative to the robotic arm base). Control unit 9 controls the end effector of robotic arm 81 to grasp the calibration plate and move it to at least 15 different poses within its field of view (each pose includes a different 3D position and rotation angle). For each pose, the homogeneous transformation matrix T of the robotic arm end effector in the robotic arm's base coordinate system is recorded. btg Simultaneously, the visual positioning camera 4 captures images of the calibration board, and the transformation matrix T of the calibration board in the camera coordinate system is calculated using the PnP algorithm (solvePnP). ctbo Due to the transformation matrix T between the calibration plate and the end effector of the robotic arm. gtb It is fixed; solve for the hand-eye matrix T. ctba Satisfy the equation:

[0059] T ctba *T ctbo =T btg *T gtb

[0060] After collecting multiple sets of data, control unit 9 uses the Tsai or Park algorithm to solve for T. ctbaFinally, the rotation matrix R from the camera coordinate system to the robot arm's base coordinate system is obtained. ctba Translation vector t ctba This matrix is ​​used to convert the visually recognized pixel coordinates into a three-dimensional spatial pose that the robotic arm can execute.

[0061] (III) Joint calibration of the moving mechanism and the vision camera

[0062] The visual positioning camera 4 is mounted on the bottom of the mounting base 3 and moves with the first moving component 22 and the lifting component 21. Therefore, there is a fixed translational relationship between the camera coordinate system and the moving mechanism coordinate system. The control unit 9 is calibrated through the following steps: controlling the moving mechanism 2 to move the camera to a calibration point at a known location (e.g., a precision cylindrical pin fixed on the support frame 1), and recording the current three-dimensional coordinates (X, Y, X) of the moving mechanism. m ,Y m Z m The visual positioning camera 4 captures images of the calibration points, extracts the center pixel coordinates (u,v) of the image through contour detection, and converts them into coordinates (X,V) in the camera coordinate system using the camera intrinsic parameter matrix. c ,Y c Z c Since the world coordinates of the calibration point are known, the translation vector t from the camera coordinate system to the moving mechanism coordinate system can be solved. ctm Any subsequent visual positioning results (Δu, Δv) are converted into the displacement (ΔX, ΔY) that the moving mechanism needs to compensate for using the following formula:

[0063] ΔX=Δu×S x ;

[0064] ΔY = Δv × S y ;

[0065] Among them, S x S y S is the pixel equivalent (mm / pixel). In this embodiment, S x =S y ≈0.00335mm / pixel.

[0066] III. Detailed Implementation of the Printhead Status Monitoring Module:

[0067] The printhead status monitoring module includes a temperature acquisition unit, a current acquisition unit, a timing and counting unit, and an in-situ detection unit.

[0068] Temperature acquisition unit: Each printhead embeds a PT100 platinum resistance temperature sensor. Control unit 9 reads the temperature every 100 milliseconds and calculates the temperature value according to the Callendar-Van Dusen equation (above 0°C: R...). t=R0×(1+A×t+B×t²), where R0=100Ω, A=3.9083×10 -3 ℃ -1 B = -5.775 × 10 -7 ℃ -2 To speed up the calculation, a resistance-temperature correspondence table from -20℃ to 300℃ can be pre-established, and the temperature can be obtained by interpolation.

[0069] Current acquisition unit: The TMC2209 extrusion motor driver chip has a built-in current sensor, which samples the current through an ADC (12-bit resolution) and converts it into a current value I. act The current value conversion process is as follows:

[0070] Let the raw value read by the ADC be ADC value (Value range 0~4095, corresponding to 0~3.3V input), then the analog voltage U output by the driver chip adc for:

[0071] U adc =(ADC value / 4095)×3.3 (volts)

[0072] The transfer function for the internal current sensing of the TMC2209 is: I act =U adc / (R sense ×Gain), where R sense The internal equivalent sampling resistance is 0.11Ω (typical value), and Gain is the internal amplification factor (fixed at 10). Therefore, the actual motor current I... act The formula for calculating (unit: ampere) is: I act =(ADC value / 4095)×3.3 / (0.11×10);

[0073] Timing Counting Unit: Timing Accumulation Variable life seconds Stored in FRAM, it increases by 1 per second when the printhead heating rod relay is closed and the extrusion motor is enabled. Preset lifespan threshold L. max =720,000 seconds (200 hours). Extrusion length accumulator filament length_mm Based on the cumulative step pulses: extrusion wheel diameter D = 12mm, step angle 1.8°, subdivision number 16, advance length per step = π×D / (360 / 1.8×16)≈0.09425mm. Replacement is triggered when the cumulative extrusion length exceeds 5000 meters.

[0074] In-place detection unit: An in-place sensor is installed at the bottom of each slot in the placement box 82. The control unit 9 reads the switch status via GPIO (low level indicates a printhead is present). Each spare printhead 83 has a DS2431 EEPROM embedded on its side, and its 64-bit unique serial number and cumulative usage data are read via a single bus. If the read fails or the ID does not match, it is determined to be unusable.

[0075] Replacement trigger conditions: When the absolute value of the deviation between the actual temperature and the target temperature is >10℃ for 5 consecutive samplings (within 0.5 seconds), or the temperature rise rate during heating is <0.5℃ / s for 10 seconds, or the extrusion current is >1.44A for 30 milliseconds, or the cumulative lifespan exceeds the threshold, or a manual replacement instruction is received, the status monitoring module sends a replacement request to the decision module.

[0076] It should be further noted that the extrusion motor is a two-phase hybrid stepper motor with a rated phase current of 1.2A. The driver chip used is the TMC2209, which integrates a non-destructive current detection circuit, allowing real-time monitoring of the motor winding current without the need for an external sampling resistor. The TMC2209 measures the voltage drop during the power transistor's conduction period, amplifies it through an internal differential amplifier, and outputs an analog voltage signal from its pin. This signal is proportional to the instantaneous motor current.

[0077] The analog voltage signal is input to the analog-to-digital converter (ADC) of the control unit 9. The ADC is a 12-bit successive approximation type, with a reference voltage of 3.3V, an input range of 0~3.3V, and a conversion period of 10 microseconds. The control unit 9 reads the ADC conversion result every 10 milliseconds, that is, it reads about 1000 current samples in each extrusion cycle, and takes the maximum value as the peak current of that cycle to avoid misjudgment caused by PWM switching noise.

[0078] Extrusion motor current over-limit judgment:

[0079] Set the rated current I rated =1.2A, overcurrent threshold I threshold =1.2×I rated =1.44A. Considering that the stepper motor may experience instantaneous current spikes (lasting less than 1 millisecond) during startup and commutation, a continuous sampling method is adopted to avoid false triggering: the controller 9 continuously samples the current value with a period of 10 milliseconds, and only when 3 consecutive sampling values ​​(i.e., 30 consecutive milliseconds) exceed I... threshold Only when the current exceeds the limit or the rotor is locked is it considered a true overcurrent or stall fault. If it is only a single instantaneous spike, it is not considered a fault.

[0080] When a current over-limit fault is detected, the printhead status monitoring module immediately sends a replacement request to the decision and logic scheduling module, and at the same time executes a protection action: immediately cuts off the enable signal of the extrusion motor to prevent further damage to the drive circuit or extrusion mechanism.

[0081] IV. Precise Positioning Implementation of the Visual Positioning and Processing Module

[0082] During the fine-positioning phase of the process changeover, the visual positioning and processing module performs the following calculations:

[0083] (I) Image Acquisition and Preprocessing

[0084] The visual positioning camera 4 acquires a 1920×1200 pixel grayscale image with an exposure time of 50 milliseconds. The control unit 9 sequentially performs Gaussian filtering (kernel size 5×5, standard deviation σ=1.5) on the image to remove noise, and then performs histogram equalization to enhance contrast.

[0085] (II) Feature Extraction

[0086] Center recognition of the robotic arm gripper: A circular reflective marker with a diameter of 5mm is affixed to the gripper at the end of the robotic arm 81. The control unit 9 employs a circle detection algorithm based on Hough transform, setting the radius range to 4-6mm and the accumulator threshold to 30, to detect the sub-pixel coordinates (u) of the circle's center. claw ,v claw Simultaneously, by detecting the direction of the line connecting two symmetrical marker points on the gripper, the rotation angle θ of the gripper is calculated. claw (Radian measure, range from -π to π).

[0087] Identification of the gripping area of ​​the spare printhead: Each spare printhead 83 has an AprilTag (10mm × 10mm, family Tag36h11) affixed to its outer shell. The control unit 9 runs an AprilTag detection algorithm (such as OpenCV's Apriltag module) to extract the pixel coordinates of the four corner points of the tag, and then calculates the three-dimensional position and rotation angle of the tag center in the camera coordinate system using the PnP algorithm. Among these, the precise center position of the gripping area (u...) tip ,v tip The coordinates of the tag center are added to the pre-calibrated offset (Δu). offset ,Δv offset The offset is obtained by measuring the physical distance (in millimeters) between the gripping area and the center of the tag, and then multiplying it by the pixel / millimeter ratio.

[0088] (III) Calculation of Compensation Amount

[0089] Assuming that after the current coarse positioning is completed, the target pixel position of the robotic arm gripper center should be the image center (u center ,v center However, the actual detected gripper center is (u claw ,v claw Then the pixel deviation is:

[0090] Δu claw =u claw -u center ;

[0091] Δv claw =v claw -v center ;

[0092] Similarly, the deviation between the actual pixel position of the gripping part of the spare printhead and the target position (which is also the image center) is:

[0093] Δu tip =u tip -u center ;

[0094] Δv tip =v tip -v center ;

[0095] Since the robotic arm gripper and the spare printhead gripping area should be aligned simultaneously, control component 9 takes the weighted average of the two as the final compensation amount, with a weighting coefficient of 0.5 for each.

[0096] Δu=0.5*Δu claw +0.5*Δu tip ;

[0097] Δv=0.5*Δv claw +0.5*Δv tip ;

[0098] Convert to physical displacement: ΔX comp =Δu×S x ΔY comp =Δv×S y Rotational compensation Δθ=θ claw .

[0099] The rotation angle compensation Δθ is directly taken as the angle θ detected by the gripper. claw (Because the gripping part of the spare printhead should maintain the same posture as the gripper). This compensation amount is sent to the motion control module, which superimposes it onto the current coarse positioning coordinates, driving the first moving component 22 and the second moving component 6 to perform micro-motion. The above fine positioning process is repeated 2-3 times until the absolute values ​​of Δu and Δv are both less than 0.5 pixels (corresponding to a physical displacement of approximately 0.02 mm), at which point the fine positioning is considered complete.

[0100] (iv) Two optional implementation methods for object detection algorithms

[0101] When the visual positioning and processing module identifies the reflective markings on the end gripper of the robotic arm 81 and the AprilTag on the spare print head 83, it supports two optional algorithm implementation methods. Those skilled in the art can choose one or use a combination of them according to the accuracy requirements, computing resources and ambient lighting conditions of the actual application scenario.

[0102] Method 1: Traditional visual algorithms based on template matching

[0103] When the equipment operates in a stable lighting environment, the target features are clear, and computing resources are limited, a template matching algorithm based on normalized cross-correlation (NCC) is adopted.

[0104] First, during the equipment debugging phase, the control unit 9 acquires an image of the gripper marker points in a standard posture and an image of the gripping area of ​​the spare print head. Rectangular regions containing the target are then cropped from each image as template images T(u,v), with a size of 32×32 pixels. During the real-time detection phase, for the currently acquired and preprocessed image I(u,v), the control unit 9 slides the template within a preset region of interest (ROI) and calculates the normalized cross-correlation value R(x,y) at each location.

[0105]

[0106] in, The average value of the image within the template coverage area. The template mean is used. R(x,y) ranges from -1 to 1, with values ​​closer to 1 indicating a higher degree of matching. Control unit 9 sets a matching threshold of 0.85, and the position (x,y) where R(x,y) reaches its maximum value is used as the target center. If the maximum value is below the threshold, the matching is considered a failure, triggering a visual localization retry. This method has low computational cost, with a single matching time of approximately 15 milliseconds on a 1920×1200 image, making it suitable for scenarios with high real-time requirements.

[0107] Method 2: Object detection algorithm based on deep learning

[0108] When ambient lighting varies significantly, or the target may be partially occluded or have changing pose, a lightweight convolutional neural network is used for target detection. The control unit 9 incorporates a pre-trained YOLOv8-nano model containing approximately 2 million parameters. The input image size is 640×640 pixels, and the output categories include gripper markers and the print head's grasping area. The network structure consists of a backbone network (CSPDarknet), a neck network (PAN-FPN), and a detection head.

[0109] The training process is as follows: 5000 images of the gripper and spare printhead under different lighting, angles, and occlusion conditions were pre-collected. The target bounding boxes were manually labeled using the LabelImg tool, and the images were divided into training, validation, and test sets in an 8:1:1 ratio. A stochastic gradient descent optimizer was used with an initial learning rate of 0.01, momentum of 0.937, and weight decay of 0.0005, for 300 epochs.

[0110] During actual inference, controller 9 calls the ONNX Runtime or TensorRT inference engine, inputting a 640×640 image into the network. The network outputs the bounding box center coordinates, width, height, and confidence score for each detected target. The confidence threshold is set to 0.6, and the IOU threshold for non-maximum suppression (NMS) is set to 0.5. The center of the bounding box of the target with the highest confidence score is extracted as the target center pixel coordinates (utarget, vtarget).

[0111] The switching strategy between the two methods is as follows: Control component 9 defaults to template matching. When the confidence level of three consecutive matches is below 0.7, it automatically switches to deep learning. After deep learning stabilizes, if the confidence level of ten consecutive detections is above 0.9, it switches back to template matching to reduce computational load. Both methods share the subsequent compensation calculation process, which is transparent to the upper-level decision-making module.

[0112] V. PID Control Algorithm for Motion Control Module

[0113] The motion control module employs position-speed-current three-closed-loop control for each drive axis of the lifting assembly 21, the first moving assembly 22, and the second moving assembly 6. Taking the X-axis of the first moving assembly 22 as an example, its control algorithm is as follows:

[0114] (a) Position ring

[0115] The position loop period is 1 millisecond. Given the target position X ref (Unit: mm), Feedback position X fdb From the encoder. Position error e p =X ref -X fdb The position loop output is the speed command V. ref :

[0116] V ref =K pp *e p +K pi *∫e pdt +K pd *d(e p ) / dt

[0117] Among them, K pp Kpi K pd These are the proportional, integral, and differential coefficients, respectively, which are tuned using the Ziegler-Nichols method to obtain typical values: K pp =50 (mm / s) / mm, K pi =0.5 (mm / s) / (mm·s), K pd =0.1 (mm / s) / (mm / s). The integral term is limited, with the maximum integral not exceeding ±50 mm / s to prevent integral saturation.

[0118] (ii) Speed ​​Loop

[0119] The velocity loop period is 0.5 milliseconds. Given a velocity V... ref With feedback speed V fdb error e v =V ref -V fdb The speed loop output is the current command I. ref :

[0120] I ref =K vp *e v +K vi *∫e v dt;

[0121] Among them, K vp =0.2 amperes / (mm / s), K vi =2 amperes / (mm / s·s). The current command is sent to the servo driver, which drives the motor via vector control. The motion control module also implements S-curve acceleration and deceleration planning to avoid mechanical shock during start-up and shutdown. The acceleration change rate J of the S-curve is set to 500 mm / s³.

[0122] VI. Force-position hybrid control of the robotic arm collaborative control module

[0123] The robotic arm 81 is a six-axis articulated industrial robotic arm. Its controller receives the target pose (x, y, z, Rx, Ry, Rz) and force / torque target from the end effector. The robotic arm collaborative control module sends commands every 5 milliseconds via Modbus-TCP.

[0124] (a) Force-controlled gripping when disassembling an old printhead

[0125] The controller 9 sends a "grip" command, setting the target force for gripper closure to 15 Newtons, with an allowable error of ±2 Newtons. The robotic arm controller uses an impedance control algorithm to convert gripper closure position control into force control. When the gripper force feedback reaches 13 Newtons, it is determined that the printhead has been contacted; the force is further increased to 15 Newtons and stabilized for 100 milliseconds, indicating successful gripping. If the force feedback remains less than 5 Newtons within 2 seconds, gripping is considered a failure, and the replacement process is aborted. After successful gripping, the automatic locking mechanism is first unlocked, and then the printhead 5 is removed from the mounting base 3.

[0126] (ii) Force control insertion when installing a new printhead

[0127] Mounting base 3 has four spring pin connectors and one mechanical positioning pin. After the robotic arm grasps the spare printhead 83, the controller 9 sends an "install" command, setting the end effector to move in force control mode along the negative Z-axis (downward), with a target force of 10 Newtons and a maximum movement speed limited to 2 mm / s. The robotic arm controller converts Z-axis position control into force control: when resistance is encountered during insertion, the force feedback increases, and the robotic arm automatically reduces its movement speed; when the force feedback reaches 10 Newtons, the robotic arm stops descending and remains stationary for 100 milliseconds. At this time, the presence sensor at the bottom of mounting base 3 should be triggered. The controller 9 reads the presence sensor signal; if triggered, it sends a "lock" command to the automatic locking mechanism on mounting base 3 (specifically, an electromagnetic lock (energized and engaged), which mechanically locks the printhead by engaging the locking pin in the locking slot). After receiving locking feedback again (which can be confirmed by electromagnet current monitoring or an independent microswitch), the controller 9 commands the robotic arm to open its gripper and retract to a safe position (20mm upward in the Z-axis direction). If the in-situ sensor is not triggered but the force feedback has reached 10 Newtons, it is determined to be stuck and a fault alarm is issued.

[0128] VII. Finite State Machine Implementation of the Decision and Logic Scheduling Module

[0129] The finite state machine (FSM) built into the decision module contains the following 7 states, and the transition process is as follows: Figure 6 As shown, the state transition conditions are as follows:

[0130] Initialization state: Automatically enters this state after the device is powered on. It performs a hardware self-test, reads calibration parameters, and checks the spare printhead list. Upon completion, it automatically transitions to "Printing Run State".

[0131] Printing operation status: Normal additive manufacturing operation is being performed. Listening for replacement requests from the status monitoring module. If a request is received, the current printing breakpoint is immediately saved (including the current layer number, coordinate position X / Y / Z within the current layer, cumulative extrusion amount, extrusion rate, etc.), and then the moving mechanism 2 is controlled to raise the print head to a safe height of Z=+50mm and enter the "replacement preparation state".

[0132] Change to preparation state: The motion control module is called sequentially to perform coarse positioning, and the vision module is called to perform fine positioning (repeated up to 3 times). If the fine positioning is successful (deviation < 0.5 pixels), the process will proceed to "Change execution state"; if it fails, after 3 retries, the process will proceed to "Fault handling state".

[0133] Change execution state: Invoke the robotic arm collaborative control module to execute the sequence of disassembly → placing the old head → grabbing the new head → installing the new head. After each step is completed, wait for the robotic arm to return a "success" status code. If any step returns a failure or times out (maximum 30 seconds per step), proceed to "fault handling state". After all steps are successful, proceed to "change verification state".

[0134] Change verification status: Call the status monitoring module to read the ID of the newly installed printhead and the initial value of the temperature sensor (which should be within the range of room temperature ±5℃), and command the extrusion motor to idle at a speed of 5 mm / s for 5 steps to check if the current is within the rated range. If the verification passes, update the life counter (reset the cumulative time of the new printhead to zero or read the historical value from the EEPROM), and then switch to "Restore Printing Status"; if the verification fails, switch to "Fault Handling Status".

[0135] Resume printing status: Read the coordinates and extrusion volume at the time of the printing interruption from the saved breakpoint data, command the motion control module to move to that coordinate using an S-curve acceleration and deceleration method, and restart extrusion and heating. The recovery process requires waiting for the printhead temperature to reach the target value (temperature difference <2℃) before extrusion can begin. After recovery is complete, switch to "print running status".

[0136] Fault handling status: Stop all movement, disconnect the heating rod power supply, issue an audible and visual alarm (buzzer sounds continuously, red LED flashes), and display the fault code on the human-machine interface. After the user presses the "Reset" button, the equipment will re-enter the "initialization state".

[0137] Each state of the FSM starts a watchdog timer (with a period of 1 second) during execution. If the state execution time exceeds the maximum allowed time (e.g., the maximum allowed time for the change preparation state is 60 seconds), it will be forcibly switched to the "fault handling state".

[0138] VIII. Verification Algorithm for Data Storage and Self-Test Module

[0139] (a) CRC check of calibration parameters

[0140] When storing all calibration parameters (camera intrinsics, distortion coefficients, hand-eye matrix, motion mechanism transformation matrix, etc.), controller 9 calculates their CRC32 checksum (polynomial 0x04C11DB7, initial value 0xFFFFFFFF). This checksum is recalculated and compared with the stored checksum each time the data is loaded. If they do not match, the system prompts "Calibration data is corrupted, please recalibrate" and refuses to start.

[0141] (ii) Three-sector redundant backup of breakpoint data

[0142] Each time the breakpoint data (including X / Y / Z coordinates, extrusion amount, and current layer G-code line number) changes, it is written to three different sectors (sector A, sector B, and sector C) of the FRAM. During each read operation, two sectors are read simultaneously and compared. If they match, the data is used; otherwise, a third backup sector (sector C) is read, and the correct data is determined by majority vote. If all three sectors are inconsistent, the data is considered corrupted, and an alarm is triggered. This ensures accurate return to the breakpoint upon recovery after an unexpected power outage.

[0143] (III) Writing printhead life data

[0144] Each printhead's built-in EEPROM (DS2431, 1Kbit capacity) stores the cumulative usage time (uint32_t, in seconds) at addresses 0x00-0x03 and the cumulative extrusion length (uint32_t, in millimeters) at addresses 0x04-0x07. Controller 9 writes an update value to the currently used printhead's EEPROM every 10 seconds. Before writing, the current value is read, and writing is only performed if the change exceeds 10 seconds, reducing the number of erase / write cycles. After writing, a readback verification is performed. If the readback value is inconsistent with the written value, it is retried 3 times. If it still fails, a "printhead communication failure" alarm is issued.

[0145] IX. Alarm Classification and Display of the Human-Computer Interaction Module

[0146] The touch-screen human-computer interaction interface (7-inch, 800×480 resolution) displays the following content in real time:

[0147] Main area: Displays the current printhead temperature (0-300℃ scale) and remaining lifespan percentage (0-100%) in the form of a dashboard.

[0148] List area: Displays the status of spare printheads in the 8 slots of the placement box 82, including model (e.g., "0.4mm-PLA"), remaining life, and availability status ("available" or "missing").

[0149] Status bar: Displays the current printing status ("Printing", "Replacing", "Fault"), current layer number, and printing time.

[0150] Alarm pop-up: When a fault occurs, a semi-transparent red window will pop up, displaying the fault code and troubleshooting suggestions. The fault codes are defined as follows:

[0151] E101: Printhead temperature abnormal (it is recommended to check the heating element or thermocouple).

[0152] E102: Extrusion motor overcurrent (it is recommended to clean the nozzle or check the extrusion gears).

[0153] E103: Printhead has reached the end of its lifespan (please replace with a new printhead).

[0154] E201: Visual positioning failed (Please check if the camera lens is clean or if the calibration is accurate).

[0155] E202: Robotic arm failed to grasp (check the placement of the spare printhead or the gripper force sensor).

[0156] E301: Mounting bracket locking failed (check electromagnet and presence sensor)

[0157] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0158] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A 3D printing head with automatic positioning replacement function and an additive manufacturing device, comprising a support frame (1), characterized in that: The support frame (1) is provided with a moving mechanism (2) at the top. The moving mechanism (2) includes a lifting component (21) installed at the top of the support frame (1), a first moving component (22) integrated in the lifting component (21), and a moving plate (23) installed in the first moving component (22). The outer wall of the moving plate (23) is fixedly installed with a mounting base (3). The bottom of the mounting base (3) is equipped with a visual positioning camera (4) and a print head body (5). The support frame (1) is also provided with a second moving component (6). The second moving component (6) is installed with a base plate (7) at the top. The base plate (7) is provided with a replacement mechanism (8) at the top. The replacement mechanism (8) includes a robotic arm (81) and a placement box (82) fixedly installed at the top of the base plate (7), and multiple spare print heads (83) embedded in the placement box (82). The support frame (1) is also fixedly installed with a control component (9). The control element (9) is configured to: (a) Monitor the working status parameters of the printhead body (5) in real time, and automatically generate a replacement request when the working status parameters exceed a preset threshold; (b) In response to the replacement request, control the moving mechanism (2) to move the printhead body (5) to the coarse positioning coordinates, and control the second moving component (6) to move the replacement mechanism (8) to the corresponding receiving coordinates; (c) Start the visual positioning camera (4) to acquire images including the end of the robotic arm (81) and the spare print head (83), calculate the compensation displacement through image processing, and control the moving mechanism (2) and / or the second moving component (6) to perform fine positioning adjustment according to the compensation displacement; (d) After the precision positioning is completed, the robotic arm (81) removes the print head body (5) from the mounting base (3) and puts it into the placement box (82), and then grabs a spare print head (83) from the placement box (82) and installs it onto the mounting base (3); (e) After verifying that the newly installed printhead is working properly, control the moving mechanism (2) to move the new printhead to the printing interruption point to resume the additive manufacturing operation.

2. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 1, characterized in that: The control unit (9) includes a motion control module, a vision positioning and processing module, a robotic arm collaborative control module, a printhead status monitoring module, a decision and logic scheduling module, a human-machine interaction module, and a data storage and self-test module. The motion control module is electrically connected to the lifting assembly (21), the first moving assembly (22), and the second moving assembly (6), respectively. The vision positioning and processing module is electrically connected to the vision positioning camera (4). The robotic arm collaborative control module is communicatively connected to the controller of the robotic arm (81). The printhead status monitoring module is electrically connected to the sensors and storage chips in the printhead body (5) and the spare printhead (83), respectively. The decision and logic scheduling module is connected to the other modules through an internal message bus.

3. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 2, characterized in that: The printhead status monitoring module includes a temperature acquisition unit, a current acquisition unit, a timing and counting unit, and an in-situ detection unit. The temperature acquisition unit is used to read the temperature sensor data in the printhead body (5) and the spare printhead (83) in real time. The current acquisition unit is used to monitor the drive current of the extrusion motor. The timing and counting unit is used to accumulate the total power-on time of the printhead body (5) or the length of the extruded filament. The in-situ detection unit is used to detect the placement status of each spare printhead (83) in the placement box (82) and read its identification. When abnormal temperature, excessive current, accumulated usage time exceeding the preset lifespan threshold, or a manual replacement signal is received, the printhead status monitoring module sends a replacement request to the decision and logic scheduling module.

4. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 2, characterized in that: The decision-making and logic scheduling module has a built-in finite state machine, which includes at least an initialization state, a printing operation state, a replacement preparation state, a replacement execution state, a replacement verification state, a print resumption state, and a fault handling state. When a replacement request is received from the printhead status monitoring module, the decision-making and logic scheduling module controls the printing to be interrupted and saves the current print breakpoint data. It then sequentially drives the motion control module to perform coarse positioning, the vision positioning and processing module to perform fine positioning, the robotic arm collaborative control module to perform disassembly and installation, and the printhead status monitoring module to perform post-replacement verification. After successful verification, the motion control module resumes the printing job. If any sub-step fails, the system enters the fault handling state and issues an alarm.

5. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 4, characterized in that: The visual positioning and processing module is equipped with hand-eye calibration parameters and target detection algorithm. During the fine positioning process, the visual positioning and processing module controls the visual positioning camera (4) to acquire images including the end gripper of the robotic arm (81) and the spare print head (83), identifies the center coordinates and rotation angle of the gripper center and the gripping part of the print head, calculates the compensation displacement (Δx, Δy, Δθ) through the coordinate transformation matrix and sends it to the motion control module.

6. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 4, characterized in that: The robotic arm collaborative control module integrates a force-position hybrid control function. When installing the spare printhead (83), the robotic arm collaborative control module sends a force control mode command to the robotic arm (81) to push the spare printhead (83) into the mounting base (3) with a preset target force until the contact sensor on the mounting base (3) is triggered, and then controls the automatic locking mechanism to lock it. When disassembling the printhead body (5), the robotic arm collaborative control module controls the robotic arm (81) to grab the printhead with a force feedback threshold and moves it into the placement box (82) after unlocking.

7. The 3D printing head and additive manufacturing apparatus with automatic positioning and replacement function according to claim 2, characterized in that: The data storage and self-test module includes a non-volatile memory for storing system calibration parameters, replacement history logs, life counters of each printhead, and breakpoint data. When the device is powered on, the data storage and self-test module executes a self-test program to check the communication status of the motion control module, the visual positioning camera (4), the robotic arm (81), and the integrity of the calibration matrix. The printing job is allowed to start only after the self-test is passed.

8. The 3D printing head with automatic positioning and replacing function and the additive manufacturing equipment according to claim 1, characterized in that: The placement box (82) has multiple independent slots. Each slot has an in-situ sensor installed at the bottom to detect the in-situ status of the spare printhead (83). Each slot has a spring probe on the side that contacts the built-in storage chip of the spare printhead (83) to read the model, parameters and cumulative usage data of the spare printhead (83).

9. The 3D printing head with automatic positioning and replacing function and the additive manufacturing equipment according to claim 1, characterized in that: The lifting component (21) is a screw lifting mechanism, and the first moving component (22) and the second moving component (6) are both synchronous belt linear modules; the moving direction of the first moving component (22) and the moving direction of the second moving component (6) are perpendicular to each other in the horizontal plane.

10. The 3D printing head with automatic positioning and replacing function and the additive manufacturing equipment according to claim 1, characterized in that: The control unit (9) is also connected to an emergency stop button and a touch-screen human-machine interface; the emergency stop button has the highest priority and can interrupt all actions of the motion control module and the robotic arm collaborative control module and cut off the drive power; the touch-screen human-machine interface is used to display the current printhead temperature, remaining life, spare printhead list and fault alarm information, and to receive manual replacement, reset and zeroing operation commands.

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