Nozzle calibration system and method for a 3D printer, eddy current sensor and detection assembly

Abstract

The application provides a nozzle calibration system and method of a 3D printer, an eddy current sensor and a detection assembly. The calibration system comprises a 3D printer, the 3D printer comprising a nozzle and a controller, the nozzle being movably arranged in a printing space of the 3D printer. The calibration system further comprises an eddy current sensor arranged in the printing space. The controller is configured to control the nozzle to move above the eddy current sensor, collect a detection value of the eddy current sensor, and obtain a change curve of the detection value in a moving direction. The actual position of the nozzle is determined according to the change curve. The calibration value of the nozzle is determined based on the actual position and the center position of the eddy current sensor. The whole calibration system is simple in structure, convenient to install, and basically does not need to additionally increase the space of the 3D printer, and can be applied to a miniaturized 3D printer.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, specifically to a nozzle calibration system and method for a 3D printer, an eddy current sensor and detection component for nozzle calibration of a 3D printer. Background Technology

[0002] In recent years, 3D printers (also known as additive printers) have developed rapidly. Core xy structure 3D printers include nozzles movable in the XY plane and a printing platform movable along the Z-axis. The nozzles print layer by layer on the printing platform to form a 3D product. Other structures, such as gantry or cantilever structures, include printing nozzles movable along the Z-axis. The nozzles and printing platform move relative to each other in the xy plane to form the 3D product. In 3D printing, the precise coordinates of the nozzles within the printer are crucial for ensuring printing accuracy. This is especially true in dual-nozzle printers; if the coordinates of both nozzles deviate, the resulting printed product will have more serious problems.

[0003] To address these issues, the first method is manual calibration, which involves printing lines with varying offsets using the nozzle to determine its position. The second method uses a force sensor for calibration; a force sensor is installed on the nozzle, and the nozzle drives the sensor to touch a calibration object (such as a cylinder) fixed to the printing platform from different directions to calculate the nozzle's coordinates relative to the calibration object, thus determining the nozzle's offset. The third method is visual calibration, which uses a camera placed inside the 3D printer to take pictures of the nozzle and then calculate its coordinates.

[0004] However, the manual calibration method described above is complex to operate and has low accuracy; the force sensor method and the visual calibration method have high requirements for the cleanliness of the nozzle. Summary of the Invention

[0005] Based on the above situation, the main purpose of this application is to provide a nozzle calibration system and method for 3D printers, an eddy current sensor and detection components for nozzle calibration of 3D printers. The entire calibration system has a simple structure, is easy to install, and basically does not require additional space to be added to the 3D printer, and can be applied to miniaturized 3D printers.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] A first aspect of this application provides a nozzle calibration system for a 3D printer, including a 3D printer, the 3D printer including a nozzle and a controller, the nozzle being movably disposed within the printing space of the 3D printer; the calibration system further includes an eddy current sensor disposed within the printing space; the controller is used for:

[0008] The nozzle is controlled to move above the eddy current sensor, and the detection value of the eddy current sensor is collected to obtain the change curve of the detection value in the moving direction;

[0009] The actual position of the nozzle is determined based on the change curve;

[0010] The calibration value of the nozzle is determined based on the actual position and the center position of the eddy current sensor.

[0011] Optionally, the controller is used to control the nozzle to move along a straight path above the eddy current sensor.

[0012] Optionally, the center position of the eddy current sensor includes the X-axis and Y-axis positions of the eddy current sensor in the 3D printer; the controller is used to,

[0013] The nozzle is controlled to move along a first straight line and a second straight line respectively, and the detection value of the eddy current sensor is collected to obtain a first change curve corresponding to each position on the first straight line and a second change curve corresponding to each position on the second straight line; wherein, the first straight line and the second straight line are parallel to the X-axis and Y-axis of the 3D printer respectively, and the intersection of the two is located in the central region of the eddy current sensor.

[0014] The actual position of the nozzle on the X-axis is determined based on the first change curve, and the actual position of the nozzle on the Y-axis is determined based on the second change curve;

[0015] The X-axis calibration value of the nozzle is determined based on the actual position of the X-axis and the X-axis position of the center position, and the Y-axis calibration value of the nozzle is determined based on the actual position of the Y-axis and the Y-axis position of the center position.

[0016] Optionally, the controller is used to,

[0017] The nozzle is controlled to move from the center region of the eddy current sensor, first moving an initial preset distance along the first direction of the straight path; then continuing to move along the second direction of the straight path at a preset step distance to detect a preset distance; and the detection value of the eddy current sensor is collected to obtain the change curve of the detection value along the straight path;

[0018] Wherein, the first direction is opposite to the second direction.

[0019] Optionally, the straight path includes a straight line parallel to the X-axis direction, and the controller obtains the change curve of the detected value in the X-axis direction, thereby obtaining the X-axis calibration value of the nozzle;

[0020] The straight path includes a straight line parallel to the Y-axis direction. The controller obtains the change curve of the detected value in the Y-axis direction, and then obtains the Y-axis calibration value of the nozzle.

[0021] Optionally, during the acquisition of eddy current sensor detection values, the starting end of at least one straight path of nozzle movement is located at the first end of the eddy current sensor along the straight path or outside the first end of the eddy current sensor.

[0022] Optionally, during the acquisition of eddy current sensor detection values, the termination end of at least one straight path of nozzle movement is located at the second end of the eddy current sensor along the straight path or outside the second end of the eddy current sensor.

[0023] Optionally, the actual position of the nozzle can be determined based on the peak or trough region of the change curve.

[0024] Optionally, the 3D printer is provided with two nozzles, and the two nozzles are calibrated respectively.

[0025] Optionally, the two nozzles include a first nozzle and a second nozzle;

[0026] Determining the nozzle calibration value based on the actual position and the center position of the eddy current sensor includes:

[0027] Based on the actual positions of the first nozzle and the second nozzle, the offset of the first nozzle and the second nozzle in the XY plane of the 3D printer is determined.

[0028] Optionally, one nozzle is closer to the printing platform of the 3D printer on the Z-axis than the other nozzle.

[0029] Optionally, the eddy current sensor includes a coil, the maximum dimension of the outer contour of the coil in a straight line passing through its center being 1 to 10 times the diameter of the nozzle opening; the center position of the eddy current sensor is the center position of the coil.

[0030] Optionally, the 3D printer further includes a printing platform that is movable relative to the nozzle along the Z-axis, and the eddy current sensor is disposed on the printing platform and located outside the printing area of ​​the printing platform.

[0031] Optionally, the eddy current sensor is disposed on the side wall of the printing platform.

[0032] Optionally, the printing platform includes a platform body and a mounting base, the mounting base being connected to the side wall of the platform body, and the mounting base having a mounting groove with the opening of the mounting groove facing the nozzle;

[0033] The eddy current sensor is mounted in the mounting groove and does not extend beyond the printing plane of the printing platform.

[0034] Optionally, the eddy current sensor includes a magnetic conductor, a magnetic generator, and a coil, wherein the magnetic conductor and the magnetic generator are stacked, and the coil is disposed on the side of the magnetic conductor facing away from the magnetic generator.

[0035] Optionally, the magnetic conductor has an annular groove on the side facing away from the magnetic generator; the coil is embedded in the annular groove.

[0036] Optionally, a detection component is included, the detection component comprising a base and the eddy current sensor, the first surface of the base being provided with a sensor groove; the magnetic conductor and the magnetic generating component are mounted in the sensor groove, and the eddy current sensor is disposed in the printing space via the base.

[0037] Optionally, the second side of the base is provided with a receiving groove; the eddy current sensor also includes a circuit board, which is mounted in the receiving groove.

[0038] Optionally, the printing platform includes a mounting base, the mounting base having a mounting groove for mounting the base, and a limiting structure being provided on the side wall of the mounting groove, with at least a portion of the side wall of the base cooperating with the limiting structure.

[0039] Optionally, the limiting structure includes two opposing protrusions that extend from the opening of the mounting groove to the bottom surface.

[0040] Optionally, a Z-axis calibration area is further provided on the first surface of the base; the detection component also includes a Z-axis detection plate, which is installed on the Z-axis calibration area.

[0041] Optionally, the Z-axis calibration area is provided with a receiving groove; the Z-axis detection plate is provided with multiple hollow holes, and the Z-axis detection plate covers the receiving groove.

[0042] Optionally, the 3D printer has two nozzles, and the 3D printer also includes a printing platform that is movable relative to the nozzles along the Z-axis of the 3D printer; the calibration system also includes a force sensor for detecting whether the nozzles are in contact with the Z-axis detection plate; the controller is further configured to:

[0043] The movement of two nozzles and at least one of the printing platform is controlled respectively. During the relative movement of each nozzle and the printing platform, when the touch signal of the force sensor is detected, the first relative position and the second relative position of the two nozzles and the printing platform in the Z direction are obtained respectively.

[0044] The offset of the two nozzles in the Z direction is determined based on the first relative position and the second relative position.

[0045] Optionally, the eddy current sensor is disposed on the rear edge of the printing platform and located in the middle region in the X-axis direction.

[0046] Optionally, the eddy current sensor can be detachably installed from the printing platform.

[0047] A second aspect of this application provides a nozzle calibration method for a 3D printer, the 3D printer including a nozzle movably disposed in the printing space of the 3D printer; an eddy current sensor is also disposed within the printing space; the calibration method includes the following steps:

[0048] S10: Control the nozzle to move above the eddy current sensor and collect the detection value of the eddy current sensor to obtain the change curve of the detection value in the moving direction;

[0049] S20: Determine the actual position of the nozzle based on the change curve;

[0050] S30: Determine the calibration value of the nozzle based on the actual position and the center position of the eddy current sensor.

[0051] Optionally, in step S10, the nozzle is controlled to move along a straight path above the eddy current sensor.

[0052] Optionally, step 10 includes the following steps:

[0053] S11: Control the nozzle to move along the first straight line and the second straight line respectively, and collect the detection value of the eddy current sensor to obtain the first change curve corresponding to each position of the detection value on the first straight line and the second change curve corresponding to each position of the second straight line; wherein, the first straight line and the second straight line are parallel to the X-axis and Y-axis of the 3D printer respectively, and the intersection of the two is located in the central region of the eddy current sensor.

[0054] Step S20 includes the following steps:

[0055] S21: Determine the actual position of the nozzle on the X-axis based on the first change curve, and determine the actual position of the nozzle on the Y-axis based on the second change curve;

[0056] Step S30 includes the following steps:

[0057] S31: Determine the X-axis calibration value of the nozzle based on the actual position of the X-axis and the X-axis position of the center position, and determine the Y-axis calibration value of the nozzle based on the actual position of the Y-axis and the Y-axis position of the center position.

[0058] Optionally, step S10 includes the following steps:

[0059] S12: Control the nozzle to start from the center region of the eddy current sensor, first move an initial preset distance along the first direction of the straight path; then continue to move along the second direction of the straight path according to a preset step distance to detect a preset distance; and collect the detection value of the eddy current sensor to obtain the change curve of the detection value along the straight path;

[0060] Wherein, the first direction is opposite to the second direction.

[0061] Optionally, the straight path includes a straight line parallel to the X-axis direction, to obtain a curve showing the change of the detected value along the X-axis direction, and then to obtain the X-axis calibration value of the nozzle;

[0062] The straight path includes a straight line parallel to the Y-axis direction, resulting in a curve showing the change of the detected value along the Y-axis direction, and thus obtaining the Y-axis calibration value of the nozzle.

[0063] Optionally, the preset step distance by which the nozzle moves along the X-axis is equal to the preset step distance by which it moves along the Y-axis; and / or,

[0064] The preset detection distance by which the nozzle moves along the X-axis is equal to the preset detection distance by which it moves along the Y-axis.

[0065] Optionally, both the initial preset distance and the detection preset distance are related to the outer contour dimensions of the eddy current sensor.

[0066] Optionally, the initial preset distance is 0.5 to 1 times the maximum size of the eddy current sensor, wherein the maximum size refers to the maximum size of the outer contour of the coil in the straight line direction passing through its center.

[0067] Optionally, the preset detection distance is 0.5 to 2.5 times the maximum size of the eddy current sensor.

[0068] Optionally, the preset step size is 0.01 to 0.03 times the maximum size of the eddy current sensor, wherein the maximum size refers to the maximum size of the outer contour of the coil in the straight line direction passing through its center.

[0069] Optionally, in step S10, during the process of acquiring the detection value of the eddy current sensor, the starting end of at least one straight path of the nozzle movement is located at the first end of the eddy current sensor along the straight path or outside the first end of the eddy current sensor.

[0070] Optionally, in step S10, during the process of acquiring the detection value of the eddy current sensor, the termination end of at least one straight path of the nozzle movement is located at the second end of the eddy current sensor along the straight path or outside the second end of the eddy current sensor.

[0071] Optionally, in step S20, the actual position of the nozzle is determined based on the peak or trough region of the change curve.

[0072] Optionally, the 3D printer is equipped with two nozzles, and the two nozzles are controlled to perform steps S10 to S30 respectively to obtain the calibration value of each nozzle.

[0073] Optionally, the 3D printer is provided with a first nozzle and a second nozzle, and the two nozzles are controlled to perform steps S10 to S20 respectively to obtain the actual positions of the first nozzle and the second nozzle;

[0074] Step S30 further includes the following step:

[0075] S32: Determine the offset of the first nozzle and the second nozzle on the XY plane of the 3D printer based on the actual position of the first nozzle and the actual position of the second nozzle.

[0076] Optionally, the 3D printer has two nozzles, and the 3D printer also includes a printing platform that is movable relative to the nozzles along the Z-axis of the 3D printer. The 3D printer is also equipped with a force sensor for detecting whether the nozzles are in contact with the printing panel; the calibration method further includes the step of:

[0077] S50: Control the relative movement of the two nozzles and the printing platform respectively. During the relative movement of each nozzle and the printing platform, when the touch signal of the touch sensor is detected, record the first relative position and the second relative position of the two nozzles and the printing platform in the Z direction.

[0078] S60: Determine the offset of the two nozzles in the Z direction based on the first relative position and the second relative position.

[0079] Optionally, in step S50, during the relative movement of the nozzle and the printing platform, the nozzle is also controlled to be at the printing temperature of the filament.

[0080] Optionally, before performing step S10, the nozzle temperature is also controlled to rise to the printing temperature of the filament.

[0081] A third aspect of this application provides an eddy current sensor for nozzle calibration in a 3D printer, comprising a magnetic conductor, a magnetic generating element, and a coil.

[0082] The magnetic conductive element and the magnetic generating element are stacked, and the coil is provided on the side of the magnetic conductive element that is away from the magnetic generating element.

[0083] Optionally, the magnetic conductor has an annular groove on the side facing away from the magnetic generator; the coil is recessed in the annular groove.

[0084] Optionally, the magnetic conductor is positioned in the cylindrical part in the middle of the annular groove to form a positioning magnetic focusing structure, and the coil is positioned and installed with the positioning magnetic focusing structure.

[0085] Optionally, the magnetic conductive element is further provided with a wiring groove on the side facing away from the magnetic generating element. The wiring groove passes through two opposite sidewalls of the magnetic conductive element and communicates with the annular groove.

[0086] The coil leads are recessed in the wiring groove and emerge from the two opposite side walls.

[0087] Optionally, it also includes a circuit board disposed on the side of the magnetic generating element away from the magnetic conductor;

[0088] The wiring channel also extends along two opposite sidewalls to the side of the magnetic conductor near the magnetic generating element and connects to the circuit board.

[0089] Optionally, the annular groove is further filled with adhesive, which forms a protective layer on the surface of the coil.

[0090] Optionally, a protective film is also included, which covers the side of the magnetic conductor away from the magnetic generating element to protect the coil.

[0091] Optionally, the magnetic conductive element includes a ferrite structural element.

[0092] Optionally, the magnetic generating element includes a permanent magnet or a device capable of generating a magnetic field, wherein the device capable of generating a magnetic field includes an energized coil.

[0093] A fourth aspect of this application provides a detection assembly for nozzle calibration of a 3D printer, including a base and an eddy current sensor as described in any of the preceding claims, wherein the magnetic guide and the magnetic generating element are mounted on the base.

[0094] Optionally, a sensor groove is provided on the first surface of the base, the magnetic conductor and the magnetic generator are recessed in the sensor groove, and the magnetic generator is closer to the bottom surface of the sensor groove than the coil.

[0095] Optionally, a receiving groove is provided on the second side of the base opposite to the first surface; the eddy current sensor further includes a circuit board, which is mounted in the receiving groove; the leads of the coil are electrically connected to the circuit board.

[0096] Optionally, the base includes a plate portion and a boss portion connected to one side of the plate portion; the sensor groove is disposed on the side of the plate portion opposite to the boss portion; and the receiving groove is disposed on the boss portion.

[0097] Optionally, a Z-axis verification area is further provided on the first surface of the base;

[0098] The detection component also includes a Z-axis detection plate, which is installed in the Z-axis calibration area.

[0099] Optionally, the Z-axis calibration area is provided with a receiving groove; the Z-axis detection plate is provided with multiple hollow holes, and the Z-axis detection plate covers the receiving groove.

[0100] Optionally, the receiving groove is a stepped groove, and the Z-axis detection plate overlaps the stepped surface of the stepped groove.

[0101] This application directly integrates the eddy current sensor within the printing space, resulting in a simple structure that occupies virtually no printing space in the 3D printer and does not affect the printing area. It eliminates the need for a large additional detection space for the nozzle calibration system, thus reducing the need to increase the overall 3D printer space. Furthermore, it has lower requirements for nozzle cleanliness, and the small size of the eddy current sensor broadens its applicability, expanding the scope of the calibration system, particularly for miniaturized 3D printers. In this structure, the nozzle is already located within the printing space during actual printing. Therefore, with the same length, width, and height for the 3D printer, the height of the printing space is increased, thereby increasing the printing area of ​​the part. In printers with a door frame, this also allows for a larger door frame diameter, reducing the difficulty of removing the printed part.

[0102] Other beneficial effects of this application will be explained in detail through the introduction of specific technical features and technical solutions in the specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0103] The embodiments of this application will now be described with reference to the accompanying drawings.

[0104] Figure 1 A schematic diagram of one embodiment of the nozzle calibration system for the 3D printer provided in this application;

[0105] Figure 2 , Figure 3 A schematic diagram showing the relative positions of the nozzle and the coil during the calibration process in one and two positions of the nozzle calibration system for the 3D printer provided in this application.

[0106] Figure 4 In one embodiment of the nozzle calibration system for the 3D printer provided in this application, the curve of the change of the detection value in the X-axis direction is shown.

[0107] Figure 5 A schematic diagram of the assembly of the printing platform and the detection component in one embodiment of the nozzle calibration system for the 3D printer provided in this application;

[0108] Figure 6 for Figure 5 A magnified view of a portion of the image;

[0109] Figure 7 An exploded view of the printing platform and detection components from one perspective, in one embodiment of the nozzle calibration system for the 3D printer provided in this application.

[0110] Figure 8 for Figure 7 A magnified view of a portion of point I in the middle;

[0111] Figure 9 An exploded view of the printing platform and detection components from another perspective, in one embodiment of the nozzle calibration system for the 3D printer provided in this application.

[0112] Figure 10 for Figure 9 A magnified view of a section at point II;

[0113] Figure 11 A schematic diagram of one embodiment of the detection component provided in this application;

[0114] Figure 12 An exploded view of one embodiment of the detection component provided in this application;

[0115] Figure 13 A schematic diagram of one embodiment of the magnetic conductive element in the detection component provided in this application;

[0116] Figure 14 A circuit diagram of one embodiment of the RLC oscillator in the detection component provided in this application;

[0117] Figure 15 A circuit diagram of another implementation of the RLC oscillator in the detection component provided in this application;

[0118] Figure 16 A flowchart illustrating one embodiment of the nozzle calibration method for a 3D printer provided in this application.

[0119] In the picture:

[0120] 100. Detection component; 110. Eddy current sensor; 111. Magnetic guide component; 1111. Annular groove; 1112. Wiring groove; 1113. Positioning and magnetic focusing structure; 112. Magnetic generating component; 113. Coil; 114. Circuit board; 115. Protective film; 120. Base; 121. Sensor groove; 122. Receiving groove; 123. Plate body; 124. Boss; 125. Receiving groove; 1251. Stepped surface; 130. Z-axis detection plate; 131. Hole;

[0121] 200. Printing platform; 210. Platform body; 220. Mounting base; 221. Mounting groove; 2211. Strip-shaped protrusion; 230. Printing panel; 240. Heated bed;

[0122] 300. Tool head; 310. Nozzle;

[0123] 400. Controller. Detailed Implementation

[0124] In the following detailed description of this application, certain specific details are described in detail. In order to avoid confusion with the substance of this application, well-known methods, processes, procedures and elements are not described in detail.

[0125] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0126] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0127] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0128] This application also provides a nozzle calibration system for a 3D printer, such as... Figures 1-16 As shown, the system includes a 3D printer, which includes a nozzle 310 and a controller 400. The nozzle 310 is positioned within the printing space of the 3D printer. The calibration system also includes an eddy current sensor 110, which is positioned within the printing space. The controller 400 is used for:

[0129] The nozzle 310 is controlled to move above the eddy current sensor 110 and the detection value of the eddy current sensor 110 is collected to obtain the change curve of the detection value in the moving direction. For example, the collected detection value can be matched with the corresponding point in the moving direction to obtain the change curve.

[0130] The actual position of nozzle 310 is determined based on the change curve;

[0131] The calibration value of nozzle 310 is determined based on the actual position of nozzle 310 and the center position of eddy current sensor.

[0132] This application also provides a nozzle calibration method for a 3D printer, which can be used in the aforementioned nozzle calibration system, such as... Figure 16 As shown, the calibration method includes the following steps:

[0133] S10: Control the nozzle 310 to move above the eddy current sensor 110 and collect the detection value of the eddy current sensor 110 to obtain the change curve of the detection value in the moving direction.

[0134] S20: Determine the actual position of nozzle 310 based on the change curve;

[0135] S30: Determine the calibration value of nozzle 310 based on the actual position and the center position of eddy current sensor 110.

[0136] In the above embodiments, the eddy current sensor 110 is directly placed within the printing space. The coordinates of the center of the eddy current sensor 110 are known, meaning the center position of the eddy current sensor 110 is known. However, due to manufacturing and assembly errors, even if the nozzle 310 is directly controlled to move to the aforementioned coordinates of the center of the eddy current sensor, it may not actually be located at the true center of the eddy current sensor. In this application, by controlling the nozzle 310 to move above the eddy current sensor, that is, after the eddy current sensor 110 is set up and remains stationary, the nozzle 310 moves relative to the eddy current sensor 110. In one possible implementation, the nozzle can also remain stationary while the printing platform equipped with the eddy current sensor moves. Since the nozzle 310 is a metal component (it can be partially metal, such as a metal nozzle orifice, or entirely metal), the detection value of the eddy current sensor 110 changes during the movement of the nozzle 310, resulting in a curve showing the change in the detection value along the direction of movement. Different positions of the nozzle 310 relative to the eddy current sensor 110 correspond to different points on the curve. Therefore, based on the curve, the position coordinates of the nozzle 310 when it is truly located at the center of the eddy current sensor 110 can be determined, i.e., the actual position of the nozzle 310. Then, the difference between the actual position and the previously known center position of the eddy current sensor is calculated, yielding the calibration value of the nozzle 310. The center position of the eddy current sensor can be a design value or a value pre-stored in the controller.

[0137] The printing platform may include a heated bed, and may further include at least one of a printing panel located on the heated bed and a heated bed support for supporting the heated bed, wherein the heated bed support may elastically support the heated bed or fixedly support the heated bed.

[0138] This application directly places the eddy current sensor within the printing space of the 3D printer. Its simple structure means it occupies virtually no printing space and does not affect the printing area. It eliminates the need for a large additional detection space for the nozzle calibration system, thus reducing the need to increase the overall size of the 3D printer and expanding the applicability of the calibration system. Furthermore, it has lower requirements for nozzle cleanliness, and the small size of the eddy current sensor makes it more versatile, especially suitable for miniaturized 3D printers. In this structure, the nozzle is already located within the printing space during actual printing. Therefore, with the same length, width, and height of the 3D printer, the height of the printing space is increased, thereby increasing the printing area of ​​the printed part. In printers with a door frame, it also allows for a larger door frame diameter, reducing the difficulty of removing the printed part.

[0139] The printing space refers to the three-dimensional range in which the print head of a 3D printer can move during operation, including the entire working area where the print head moves, and not limited to the actual printable part.

[0140] The printing area refers to the two-dimensional area that a 3D printer can actually print on the printing platform (i.e., the effective printing area on the XY plane).

[0141] Specifically, the controller 400 is signal-connected to the motion mechanism of the control nozzle 310. The controller 400 can be installed inside or outside the 3D printer. It can include a data acquisition unit, an identification unit, and a calibration unit. The data acquisition unit is used to perform step S10, that is, to control the nozzle 310 to move above the eddy current sensor 110 and acquire the detection value of the eddy current sensor 110 to obtain the change curve of the detection value in the moving direction. The identification unit is used to perform step S20, that is, to determine the actual position of the nozzle 310 according to the change curve. The calibration unit is used to perform step S30, that is, to determine the calibration value of the nozzle 310 based on the actual position of the nozzle 310 and the center position of the eddy current sensor.

[0142] In some embodiments, the movement trajectory of the nozzle 310 in step S10 is a plurality of concentric circles. In other embodiments, the movement trajectory of the nozzle 310 is a straight path. Specifically, in step S10, the nozzle 310 is controlled to move along a straight path above the eddy current sensor 110, that is, the controller 400 is used to control the nozzle 310 to move along a straight path above the eddy current sensor 110. The nozzle 310 moves along a straight path, resulting in a simple movement trajectory, high control accuracy, and minimal computational load, thus making the entire calibration process faster.

[0143] Understandably, a 3D printer has mutually perpendicular X-axis and Y-axis. The nozzle 310 can move along either the X-axis or the Y-axis, or simultaneously along both. The aforementioned actual position and center position refer to coordinates in the XY coordinate system. The variation curve is the curve of the detected value in the XY coordinate system; that is, the horizontal axis of the variation curve is the X or Y position coordinate in the XY coordinate system, and the vertical axis is the detected value; or, the horizontal axis of the variation curve is the detected value, and the vertical axis is the X or Y position coordinate in the XY coordinate system. Specifically, this XY coordinate system can take a point on the overall frame of the 3D printer as its origin, a corner of the printing platform as its origin, or a fixed point on the 3D printer as its zero point. The center position of the eddy current sensor 110 includes its X-axis and Y-axis positions within the 3D printer. The actual position of the nozzle includes its actual position in the X-axis direction and its actual position in the Y-axis direction within the 3D printer.

[0144] In one embodiment, an XY coordinate system is established based on the printing platform of the 3D printer, and the center position of the coil is the coordinate of the XY coordinate system. In an embodiment using a straight path, the straight path is a straight line in the XY coordinate system, and the resulting curve is the curve of the change of the detected value at different positions in the XY coordinate system. The actual position of the nozzle 310 is the position coordinate when the nozzle actually moves to the center of the eddy current sensor 110, and the resulting calibration value is the deviation value of the nozzle in the XY coordinate system (including the deviation on the X-axis and the deviation on the Y-axis, i.e., the X-axis calibration value and Y-axis calibration value below). Further, the printing platform can be a square structure, and the XY coordinate system can use a corner of the printing platform as the origin, such as choosing the corner of the printing platform near the nozzle as the origin. Since the printing platform is the carrier of the printed part, using the printing platform as the reference to establish a coordinate system is beneficial for the 3D printer to control the nozzle during the printing process, thereby improving the printing accuracy of the printed part.

[0145] The straight path in step S10 can be a 3D straight line parallel to the X-axis or Y-axis, or a straight line at an angle to the X-axis.

[0146] In one embodiment, the straight path is set as a first straight line parallel to the X-axis direction, and steps S10 to S30 are executed to obtain the X-axis calibration value of the nozzle. In another embodiment, the straight path is set as a second straight line parallel to the Y-axis direction, and steps S10 to S30 are executed to obtain the Y-axis calibration value of the nozzle.

[0147] In another embodiment, the nozzle 310 can be controlled to move along a first straight line and a second straight line respectively, thereby obtaining the X-axis calibration value and Y-axis calibration value of the nozzle 310. This embodiment can calculate the X-axis calibration value and Y-axis calibration value separately, and the control method is simple. Furthermore, the first and second change curves are two-dimensional curves, which makes determining the actual position based on the change curves more accurate and faster, further improving the calibration response speed. Specifically, step S10 includes the following steps:

[0148] S11: Control the nozzle 310 to move along the first straight line and the second straight line respectively, and collect the detection values ​​of the eddy current sensor to obtain the first change curve corresponding to each position of the detection value on the first straight line and the second change curve corresponding to each position of the second straight line, such as... Figure 4 As shown, the curve of the change of the detection value along the first straight line is illustrated; wherein the first straight line and the second straight line are parallel to the X-axis and Y-axis of the 3D printer, respectively.

[0149] Step S20 includes the following steps:

[0150] S21: Determine the actual position of the nozzle on the X-axis based on the first change curve, and determine the actual position of the nozzle on the Y-axis based on the second change curve;

[0151] Step S30 includes the following steps:

[0152] S31: The X-axis calibration value of the nozzle is determined based on the actual X-axis position and the known X-axis position of the center position of the eddy current sensor 110. The Y-axis calibration value of the nozzle is determined based on the actual Y-axis position and the Y-axis position of the center position. That is, the X-axis calibration value of the nozzle is obtained by subtracting the X-axis coordinate of the actual position from the X-axis coordinate of the center position, and the Y-axis calibration value of the nozzle is obtained by subtracting the Y-axis coordinate of the actual position from the Y-axis coordinate of the center position.

[0153] In this embodiment, the controller 400 is used to execute steps S11 to S31, and the specific steps will not be described in detail here.

[0154] In some embodiments, in step S11, the nozzle 310 is controlled to move only along a first straight line, thus obtaining only a curve showing the change of the detected value along the first straight line. In step S21, the actual position of the nozzle on the X-axis is determined only based on the first curve. In step S31, the X-axis calibration value of the nozzle is determined only based on the actual position on the X-axis and the known X-axis position of the center of the eddy current sensor 110. Similarly, in step S11, the nozzle 310 can be controlled to move only along a second straight line, thus obtaining only a curve showing the change of the detected value along the second straight line. In step S21, the actual position of the nozzle on the Y-axis is determined only based on the second curve. In step S31, the Y-axis calibration value of the nozzle is determined only based on the actual position on the Y-axis and the known Y-axis position of the center of the eddy current sensor 110.

[0155] The intersection of the first straight line and the second straight line is preferably located in the central region of the eddy current sensor 110, and more preferably, the focal point of the two lines is located on the central axis of the eddy current sensor 110.

[0156] In step S10 above, the starting position of the nozzle 310 and the length of the straight path are not limited, as long as the straight path can pass through the central region of the eddy current sensor 110. That is to say, the nozzle 310 can start moving from any position relative to the eddy current sensor 110, such as starting from any side of the eddy current sensor 110 in the direction of the straight path, or starting directly from a point inside the eddy current sensor 110; and the length of the entire path of the nozzle 310 is not limited, such as moving from one side of the eddy current sensor 110 to the other side along the direction of the straight path, moving a certain distance inside the eddy current sensor 110 along the direction of the straight path, or moving directly to the outside of the eddy current sensor 110.

[0157] In some embodiments, the nozzle 310 is first controlled to move to the central region of the eddy current sensor 110, such as to the central axis of the eddy current sensor 110, and then moved twice from the central axis of the eddy current sensor 110. Specifically, step 10 includes the following steps:

[0158] S12: Control the nozzle to move an initial preset distance along the first direction of the straight path, starting from the center area of ​​the eddy current sensor 110, such as... Figure 2 As shown, it moves a preset distance d1 along the first direction; then it continues to move along the second direction of the straight path according to a preset step size to detect a preset distance, as shown. Figure 3 As shown, the sensor moved a preset distance d2 along the second direction and collected the detection value from the eddy current sensor, obtaining the curve of the change in the detection value along the straight path, as shown. Figure 4 As shown.

[0159] In this embodiment, the controller 400 (specifically the acquisition unit 410) is used to perform the above step S12.

[0160] In this embodiment, the first direction is opposite to the second direction, meaning they are two opposite directions on a straight path. The nozzle first moves to the central region of the eddy current sensor 110, and then begins its movement from that central region. This ensures that the straight path is as close as possible to or along the diameter direction of the eddy current sensor or the centerline of the plane containing the coil of the eddy current sensor 110. This makes the characteristic region of the changing curve closer to the actual central axis of the eddy current coil 110, thereby improving the calibration accuracy.

[0161] In step S12, the detection values ​​of the eddy current sensor 110 can be collected both when the nozzle 310 moves along the first direction and the second direction; alternatively, the detection values ​​of the eddy current sensor 110 can be collected only when moving along the second direction. The former method can improve the accuracy of the change curve; the latter method can avoid frequent nozzle motion control and signal acquisition, reduce the complexity of subsequent data processing, and improve calibration efficiency.

[0162] In step S12, the straight path can be either a first straight line parallel to the X-axis or a second straight line parallel to the Y-axis. In a preferred embodiment, the straight path in step S14 includes a straight line parallel to the X-axis, i.e., the first straight line. The controller 400 obtains the change curve of the detected value in the X-axis direction, and then obtains the X-axis calibration value of the nozzle 310. That is, in step S14, when the nozzle moves along the first and second directions on the first straight line, the obtained change curve is the change curve in the direction of the first straight line. The obtained actual position of the nozzle 310 is the X-axis coordinate of the actual position of the nozzle 310. Then, based on this X-axis coordinate and the X-axis coordinate of the center position of the eddy current sensor, the X-axis calibration value of the nozzle 310 can be obtained. Similarly, the straight path in step S14 includes a straight line parallel to the Y-axis direction, i.e., the second straight line. The controller 400 obtains the change curve of the detected value in the Y-axis direction, and then obtains the Y-axis calibration value of the nozzle 310. That is, in step S14, when the nozzle moves along the first and second directions on the second straight line, the obtained change curve is the change curve in the direction of the second straight line. The actual position of the nozzle 310 is the Y-axis coordinate of the actual position of the nozzle 310. Then, based on this Y-axis coordinate and the Y-axis coordinate of the center position of the eddy current sensor, the Y-axis calibration value of the nozzle 310 can be obtained. It should be noted that it is also possible to control the nozzle to move along the X-axis to obtain the calibration value of the nozzle in the X-axis, or to control the nozzle to move along the Y-axis to obtain the calibration value of the nozzle in the Y-axis.

[0163] Regardless of which of the above-described methods of linear path movement is adopted by the nozzle 310, during the acquisition of the detection value of the eddy current sensor 110, the starting end of at least one linear path of movement of the nozzle 310 is located at the first end of the eddy current sensor 110 along that linear path or outside the first end of the eddy current sensor 110. Alternatively, during the acquisition of the detection value of the eddy current sensor 110, the ending end of at least one linear path of movement of the nozzle 310 may be located at the second end of the eddy current sensor 110 along that linear path or outside the second end of the eddy current sensor 110. In other words, the starting and ending points of each straight path can be located at opposite ends of the eddy current sensor, or outside of opposite ends, or one starting and ending point can be located at one end and the other outside the other. Alternatively, each straight path can have only one starting or ending point located at one end of the eddy current sensor 110. Of course, only some straight paths can be used, such as the first or second straight line, where the starting and ending points are located at opposite ends of the eddy current sensor, or outside of opposite ends, or one starting and ending point can be located at one end and the other outside the other. This allows for more comprehensive data collection, leading to more accurate change curves, improved accuracy in determining the actual nozzle position, and increased calibration accuracy.

[0164] In some embodiments, during the process of acquiring the detection value of the eddy current sensor 110, the starting end of at least one straight path of the nozzle 310 is located at the first end of the eddy current sensor 110 along the straight path or outside the first end of the eddy current sensor 110; or the ending end of at least one straight path of the nozzle 310 is located at the second end of the eddy current sensor 110 along the straight path or outside the second end of the eddy current sensor 110.

[0165] Specifically, in one embodiment, in step S12, when the nozzle 310 moves an initial preset distance, the nozzle 310 is at least located at one end of the eddy current sensor 110 along the straight path or outside that end; when the nozzle moves a detection preset distance, the nozzle is at least located at the other end of the eddy current sensor 110 or outside that end. That is, in step S12, the nozzle moves from one end or side of the eddy current sensor 110 to the other end or side of the eddy current sensor 110, thereby allowing the nozzle 310 to cross the entire eddy current sensor 110.

[0166] In other embodiments, in step S10, the nozzle 310 moves directly from one end or side of the eddy current sensor 110 to the other end or side of the eddy current sensor 110, as shown in Figure 1. Figure 2 , Figure 3 In the case of the eddy current sensor 110, the left side is designated as the first side and the right side as the second side. Therefore, in step S10, the nozzle can move directly from the first side to the second side, simultaneously collecting detection values ​​at each preset step distance; alternatively, the nozzle can move directly from the second side to the first side, simultaneously collecting detection values ​​at each preset step distance. In other embodiments, the nozzle can also move from the first side to the second side and then back to the first side, or it can collect detection values ​​only when moving from the second side to the first side.

[0167] Of course, regardless of the method by which the nozzle moves, the detection values ​​can be collected throughout the entire movement of the nozzle.

[0168] In another embodiment, the straight path is a straight line at an angle to the X-axis, such as a straight line at 30°, 45°, or 60° to the X-axis, and the nozzle is controlled to move along this straight line between the X-axis and the Y-axis. That is, by setting the straight path to a straight line at an angle to the X-axis direction and executing steps S10 to S30, the nozzle calibration value is obtained. By calculating this calibration value, the nozzle's calibration value on the X-axis and calibration value on the Y-axis can be obtained. Specifically,

[0169] The nozzle 310 can be controlled to move a third preset distance along a straight path at an angle to the X-axis, and the detection value at each third preset step distance can be collected to obtain the change curve of the detection value on the straight path, thereby obtaining the actual position of the nozzle, including the actual X coordinate and actual Y coordinate of the nozzle. The difference between the actual position and the center position of the eddy current sensor 110 is the calibration value of the nozzle. The calibration value can be calculated to obtain the calibration value of the nozzle on the X-axis and the calibration value on the Y-axis. Alternatively, when obtaining the actual position of the nozzle, the actual X-axis coordinate and actual Y-axis coordinate of the nozzle can be calculated first. The difference between the actual X-axis coordinate and the X-axis coordinate of the center of the eddy current sensor 110 is the calibration value of the nozzle on the X-axis, and the difference between the actual Y-axis coordinate and the Y-axis coordinate of the center of the eddy current sensor 110 is the calibration value of the nozzle on the Y-axis.

[0170] In this embodiment, the preset step distance the nozzle moves along the X-axis can be equal to or unequal to the preset step distance it moves along the Y-axis, and the preset detection distance the nozzle moves along the X-axis can also be equal to or unequal to the preset detection distance it moves along the Y-axis. In a preferred embodiment, the preset step distance the nozzle moves along the X-axis (denoted as the first preset step distance) is equal to the preset step distance it moves along the Y-axis (denoted as the second preset step distance); the preset detection distance the nozzle moves along the X-axis (denoted as the first preset detection distance) is equal to the preset detection distance it moves along the Y-axis (denoted as the second preset detection distance). This approach simplifies the algorithm and improves calibration efficiency. Of course, it is also possible that only the first preset step distance is less than the second preset step distance and equal to it, or only the first preset detection distance and the second preset detection distance are equal. In the embodiment including step S14, the initial preset distance the nozzle moves along the X-axis can also be equal to or unequal to the initial preset distance it moves along the Y-axis.

[0171] In the above embodiments, the initial preset distance and the detection preset distance can be set empirically. In a preferred embodiment, both the initial preset distance and the detection preset distance are related to the outer contour dimensions of the eddy current sensor 110. For example, the initial preset distance d1 is 0.5 to 1.5 times the maximum dimension D of the eddy current sensor 110, such as 0.5D, 0.8D, 1D, or 1.5D. The initial preset distance d1 is affected by the maximum manufacturing error. If the manufacturing error is very small, d1 can be selected as 0.5D; if the manufacturing error is relatively large, d1 can be selected as D.

[0172] In some embodiments, the preset detection distance d2 is 0.5 to 2.5 times the maximum size D of the eddy current sensor, such as d2 being 0.5D, dD, 1.5D, 2.0D, or 2.5D. Preferably, the preset detection distance d2 is selected as 2D.

[0173] To obtain a more accurate variation curve and to get calibration results faster, the preset step size is 0.01 to 0.03 times the maximum size D of the eddy current sensor, such as 0.01D, 0.02D, or 0.03D.

[0174] It should be noted that the maximum dimension D of the eddy current sensor 110 refers to the maximum dimension of the outer contour of the eddy current sensor 110. For example, when the coil of the eddy current sensor 110 is a square coil, D is the dimension of the longest side of the square coil. When the coil is a circular coil, D is the outer diameter of the coil.

[0175] In the above embodiments, the plane in which the coil of the eddy current sensor is located can be parallel to the XY plane or at an angle. Preferably, the plane in which the coil is located is parallel to the XY plane, that is, the central axis of the eddy current sensor is perpendicular to the XY plane. In this way, the accuracy of nozzle position detection can be improved, the efficiency of subsequent data processing can be improved, and the speed of calibration can be improved.

[0176] The aforementioned detection value can be the inductance of the eddy current sensor 110, the resistance of the eddy current sensor 110, or the frequency of the output signal of the eddy current sensor 110.

[0177] In step S20, the actual position of the nozzle 310 can be determined based on the characteristic values ​​on the change curve. For example, the position corresponding to the peak or trough on the change curve can be directly selected as the actual position of the nozzle. In a preferred embodiment, the actual position of the nozzle is determined based on the peak or trough region of the change curve to improve the accuracy of the actual position extraction.

[0178] In the above embodiments, before controlling the nozzle to move above the eddy current sensor 110, the nozzle is first controlled to move closer to the eddy current sensor 110 in the Z-axis direction. For example, the distance between the nozzle and the eddy current sensor 110 can be controlled to be between 0.5mm and 1.5mm, such as 0.5mm, 1mm, or 1.5mm. This can better ensure the detection stability and accuracy of the eddy current sensor. Specifically, in a 3D printer where the nozzle can move along the Z-axis, the nozzle can be controlled to move along the Z-axis to move closer to the eddy current sensor 110; in a 3D printer where the printing platform 200 can move along the Z-axis, the printing platform 200 can be controlled to move along the Z-axis to bring the nozzle closer to the eddy current sensor 110; of course, the nozzle 310 and the printing platform 200 can also be controlled to move along the Z-axis simultaneously to bring them closer to each other.

[0179] It should be noted that the above calibration method mainly calibrates the XY coordinates of the nozzle. It can be applied to both single-nozzle and dual-nozzle tool heads 300. In a dual-nozzle tool head 300, one nozzle can be used as the main material printing nozzle and the other as the auxiliary material printing nozzle; alternatively, both nozzles can be used as main material printing nozzles (such as nozzles for dual-color printing); one nozzle can be used as a backup nozzle to prevent printing failure if one malfunctions. Regardless of the tool head type, it is preferable that the controller 400 controls each nozzle to perform steps S10-S30 separately, such as controlling two nozzles to perform steps S10-S30 separately, thereby obtaining the calibration value for each nozzle, especially in embodiments where both nozzles are used as main material printing nozzles. Of course, in embodiments with multiple nozzles, only the nozzle being printed can be controlled to perform steps S10-S30.

[0180] In the embodiment where steps S10 to S30 are performed on both nozzles, the two nozzles are referred to as the first nozzle and the second nozzle, respectively. Step S30, which determines the calibration value of the nozzle based on the actual position and the center position of the eddy current sensor, includes the following steps:

[0181] S32: Determine the offset between the two nozzles in the XY plane of the 3D printer based on their respective calibration values. Specifically, determine the offset between the first nozzle and the second nozzle in the XY plane of the 3D printer based on the actual positions of the first nozzle and the second nozzle.

[0182] In other words, the controller 400 also determines the offset of the two nozzles on the XY plane of the 3D printer based on their actual positions, thereby improving the matching accuracy of the two nozzles when they work together, and improving the printing accuracy and quality of the product.

[0183] In embodiments where the tool head 300 includes two nozzles 310, it is preferable that one nozzle is positioned closer to the printing platform 200 of the 3D printer along the Z-axis than the other nozzle. Specifically, the nozzle performing the printing can be positioned closer to the printing platform 200, thus preventing the other nozzle from affecting the printed product. More preferably, one nozzle is configured to be height-adjustable relative to the other nozzle, at least in the Z-axis direction. This height adjustment ensures that the printing nozzle is always closer to the printing platform than the other nozzle, especially in embodiments where both nozzles perform main material printing.

[0184] Understandably, 3D printing is generally done layer by layer. Therefore, the nozzle also needs to be calibrated in the Z-axis direction. Especially in embodiments where the 3D printer has two nozzles, the 3D printer also includes a printing platform 200 that is relatively movable relative to the nozzle along the Z-axis of the 3D printer. The calibration system also includes a force sensor for detecting whether the nozzle is in contact with the printing platform. The force sensor can be mounted on a bracket on the tool head 300, which is non-rigidly connected to the nozzle, and can sense the contact force between the nozzle and the printing platform (or the Z-axis detection plate hereinafter) through deformation. The above calibration method also includes the following steps:

[0185] S50: Control the relative movement of the two nozzles 310 and the printing platform 200 respectively; that is, only the nozzles 310 can move, only the printing platform can move, or both the nozzles and the printing platform 200 can move. During the relative movement of each nozzle 310 and the printing platform 200, when a touch signal is detected by the touch sensor, record the first relative position and the second relative position of the two nozzles 310 and the printing platform 200 in the Z direction.

[0186] S60: Determine the offset of the two nozzles in the Z direction based on the first relative position and the second relative position.

[0187] In this embodiment, the controller 400 is also used to perform the above steps S50 and S60. Since the first relative position and the second relative position are both relative to the printing platform 200, the offset of the two nozzles on the Z-axis can be obtained through these two relative positions, thereby improving the accuracy of the two nozzles cooperating on the Z-axis and improving the quality of the printed product.

[0188] In step S50, during the relative movement of the nozzle 310 and the printing platform 200, the nozzle 310 is also controlled to be at the printing temperature of the filament.

[0189] In some embodiments, before performing step S10, the temperature of the nozzle 310 is also controlled to rise to the printing temperature of the filament.

[0190] By setting the temperature of nozzle 310 as described above, the state of the nozzle during the calibration process can be made as close as possible to the state during actual printing. This avoids the impact of nozzle thermal deformation on the nozzle position, thereby improving the calibration accuracy of the nozzle during actual printing through the above calibration system and calibration method.

[0191] In one embodiment, the eddy current sensor is disposed on the printing platform 200, the frame of the 3D printer, etc., and located outside the non-printing area. Preferably, the 3D printer further includes a printing platform 200 that is movable relative to the nozzle 310 along the Z-axis, and the eddy current sensor 110 is disposed on the printing platform 200 and located outside the printing area, such as... Figures 5-10As shown, placing the eddy current sensor 110 on the printing platform 200 facilitates its installation and removal. More importantly, during printing, the nozzle 310 actually sprays the filament onto the printing platform 200. By placing the eddy current sensor 110 on the printing platform 200, the calibration value, relative to the center of the eddy current sensor 110, is essentially also relative to the printing platform 200. This reduces the positional changes between structural components during printing, shortens the dimensional chain between the printed part and the nozzle, and thus improves printing accuracy. In some embodiments, the printing platform 200 includes a printing panel 230 and a heated bed 240. The printing panel 230 is detachably mounted on the side of the heated bed 240 facing the nozzle. After printing is complete, the printing panel 230 and the printed part can be removed from the printing space together (especially in printers with a closed or semi-closed printing space) for easy separation from the printed part. Of course, in some embodiments, the printing panel 230 and the heated bed 240 are an integral structure or a non-detachable structure. It is worth noting that the aforementioned printing area refers to the working area of ​​the nozzles on the printing platform when printing, or the area where the printed part can be located; the non-printing area, as the name suggests, is the area on the printing platform other than the printing area. The printing space refers to the operating space of the nozzles, which includes the aforementioned printing area.

[0192] Specifically, the eddy current sensor 110 can be disposed at any non-printing area of ​​the printing platform 200. In a preferred embodiment, the eddy current sensor 110 is disposed on the side wall of the printing platform 200. More preferably, it can be disposed on the side wall of the printing platform 200 near the nozzle, so as to make full use of the non-printing space within the 3D printer, improve the space utilization of the 3D printer, and make it more conducive to miniaturization. In embodiments including the printing panel 230, the eddy current sensor 110 is mounted on the heated bed 240.

[0193] Continue to refer to Figures 7-10The printing platform 200 includes a platform body 210 and a mounting base 220. The mounting base 220 is connected to the side wall of the platform body 210. A mounting groove 221 is provided on the mounting base 220, with its opening facing the nozzle 310. The mounting groove 221 is formed by recessing the side of the mounting base 220 facing the nozzle 310. In this embodiment, the eddy current sensor 110 is mounted in the mounting groove 221, and it does not extend beyond the printing plane of the printing platform 200. The mounting base 220 and its mounting groove 221 facilitate the installation and removal of the eddy current sensor 110, and ensure that the eddy current sensor 110 does not affect the printing of the tool head on the printing platform 200 when it is installed. The mounting base 220 and the platform body 210 can be integrally formed, or they can be processed separately and then installed together. The mounting groove 221 can be a groove structure with a circumferentially closed sidewall. In a preferred embodiment, the mounting groove 221 is open on the side wall area opposite to the platform body 210. This structure makes it easier to install the eddy current sensor 110 (or the detection component 100 described below).

[0194] In a preferred embodiment, the eddy current sensor 110 is disposed on the rear edge of the printing platform 200 and located in the middle region in the X-axis direction, so as to minimize the occupation of the effective space inside the printer.

[0195] Specifically, the eddy current sensor 110 is detachably mounted to the printing platform 200. When the detection component 100 (described in detail below) is provided, the detection component 100 and the printing platform 200 are detachably mounted.

[0196] In one feasible implementation, the eddy current sensor 110 includes a coil 113. The maximum dimension of the outer contour of the coil 113 of the eddy current sensor 110 used in this application, in the straight line direction passing through its center, is 1 to 10 times the opening diameter of the nozzle 310. That is, the maximum dimension D of the aforementioned eddy current sensor 110 is 1 to 10 times the opening diameter of the nozzle 310, such as 1, 3, 5, 8, 9, or 10 times the opening diameter of the nozzle 310. The center position of the aforementioned eddy current sensor 110 refers to the center position of the coil 1113. The central region and central axis of the eddy current sensor 110 both refer to the central region and central axis of the coil 110. Using an eddy current sensor 110 with a diameter 1 to 10 times that of the nozzle 310 opening diameter can improve calibration accuracy while increasing calibration efficiency.

[0197] Eddy current sensors in the prior art are commonly used for distance measurement and defect detection. Their measurement sensitivity is highly sensitive to distance; as the detection distance increases, their sensitivity and signal-to-noise ratio drop sharply. Therefore, the measurement range of such eddy current sensors is often small. However, increasing the area of ​​the coil facing the detection element (specifically a metal part) is one way to improve sensitivity, but this would make the structure too large, making miniaturization difficult.

[0198] To address the aforementioned issues, this application also provides an eddy current sensor 110, which can be used for nozzle calibration in 3D printers, and of course, can be used in the calibration system and calibration method described in any of the above embodiments. Figures 11-13 The eddy current sensor 110 includes a magnetic conductor 111, a magnetic generator 112, and a coil 113. The magnetic conductor 111 and the magnetic generator 112 are stacked. The coil 113 is located on the side of the magnetic conductor 111 facing away from the magnetic generator 112. That is, the coil 113 is located on one side of the magnetic conductor 111, and the magnetic generator 112 is located on the other side. Using this structure, the eddy current sensor 110 achieves magnetic saturation of the magnetic material by applying an external magnetic field. Magnetic saturation refers to the stage where the permeability of the magnetic conductor changes drastically when the external magnetic field changes. Therefore, the sensitivity of the eddy current coil can be greatly improved, thereby increasing its measurement range and accuracy. This allows for an increase in the range of movement of the nozzle 310 relative to the eddy current sensor 110, increasing the number of data collection points, increasing the accuracy of the change curve, and further improving calibration accuracy. Furthermore, this structure can minimize the size of the eddy current sensor 110, making it miniaturized and reducing its footprint in the 3D printer. This makes it more suitable for use in small 3D printers, such as home 3D printers. When the eddy current sensor 110 is installed in the printing space of the 3D printer, the side where the coil 113 is located faces the nozzle 310.

[0199] Continue to refer to Figure 12 and Figure 13 The magnetic conductor 111 has an annular groove 1111 on the side facing away from the magnetic generator 112. The coil 113 is recessed in the annular groove 1111, meaning the coil 113 is installed in the annular groove 111, and the coil 113 does not exceed the opening of the annular groove 111. It can be at a certain distance from the opening of the annular groove, or it can be flush with the opening of the annular groove. By setting the annular groove 111, the installation of the coil 113 can be positioned, and the size of the eddy current sensor 110 in the thickness direction (i.e., the size along the stacking direction of the magnetic conductor 111 and the magnetic generator 112) can be further reduced, which is more conducive to the miniaturization of the eddy current sensor 110.

[0200] Furthermore, the columnar portion of the magnetic conductive element 111 located in the middle of the annular groove 1111 forms a positioning and magnetic focusing structure 1113. The coil 113 is positioned and installed with the positioning and magnetic focusing structure 1113. That is, the coil 113 is sleeved on the positioning and magnetic focusing structure 1113. By using this positioning and magnetic focusing structure 1113, the coil 113 can be positioned, and the structure can also concentrate magnetic field lines. Specifically, when the eddy current sensor 110 in the above embodiment approaches a conductive or magnetically conductive material to be detected (such as the nozzle in this application), as the distance between the eddy current sensor 110 and the material to be detected decreases, the material to be detected is gradually magnetized. The magnetized material to be detected will, in turn, further enhance the magnetic field of the eddy current sensor (especially the positioning and magnetic focusing structure 1113). Since the positioning magnetic focusing structure 1113 is already close to or has reached magnetic saturation, its permeability will rapidly decrease when the external magnetic field is further strengthened. This decrease in permeability will cause the inductance of the coil 113 to also decrease rapidly, resulting in a rapid increase in the oscillation frequency of the coil 113. When the eddy current sensor 110 moves away from the workpiece, the magnetization of the workpiece weakens, the magnetic field strength of the positioning magnetic focusing structure 1113 also decreases, its permeability begins to increase, and the inductance of the coil 113 also begins to increase, resulting in a decrease in the oscillation frequency of the coil 113. Because the permeability of the positioning magnetic focusing structure 1113 in the saturated state is very sensitive to changes in the magnetic field (i.e., a small change in magnetic field strength can lead to a large change in permeability), the eddy current sensor equipped with the positioning magnetic focusing structure 1113 has high sensitivity. Even at a distance from the workpiece, it can measure a large signal amplitude, thereby greatly improving the nozzle calibration accuracy of the 3D printer.

[0201] The end of the positioning magnetic focusing structure 1113 can be flush with the side of the magnetic conductor 111 that is away from the magnetic generating member 112, or it can be closer to the magnetic generating member 112 than that side. The positioning magnetic focusing structure 1113 can extend out of the coil 113, or it can be flush with the surface of the coil 113 or lower than the surface of the coil 113.

[0202] Continue to refer to Figure 13 The magnetic conductive element 111 has a wiring groove 1112 on the side facing away from the magnetic generating element 112. The wiring groove 1112 penetrates two opposite sidewalls of the magnetic conductive element 111 and communicates with the annular groove 1111. The lead wire of the coil 113 is recessed in the wiring groove 1112 and exits from the two opposite sidewalls of the magnetic conductive element 111. That is, the annular groove 1111 and the wiring groove 1112 are located on the same side of the magnetic conductive element 111 and are connected, thereby guiding and protecting the signal line (i.e., lead wire) of the coil 113. Of course, the lead wire of the coil 113 can also be directly arranged along the surface of the magnetic conductive element 111 facing away from the magnetic generating element 112.

[0203] The eddy current sensor 110 also includes a circuit board 114, to which the leads of the coil 113 are connected. In a preferred embodiment, the circuit board 114 is disposed on the side of the magnetic generating element 112 away from the magnetic conductor 111, that is, the circuit board 114 and the magnetic conductor 111 are located on opposite sides of the magnetic generating element 112. In an embodiment with a wiring groove 1112, more preferably, the wiring groove 1112 extends along two opposite sidewalls to the side of the magnetic conductor 111 near the magnetic generating element 112 and is connected to the circuit board 114. Specifically, the leads can be connected to the circuit board 114 by means of connection, that is, the wiring groove 1112 is provided on the side of the magnetic conductor 112 with an annular groove and on two opposite sides connected to that side. In this way, the leads can be completely recessed in the wiring groove 1112 on that side and the two sides, thereby better guiding and protecting the leads.

[0204] In methods such as measuring inductance, coil 113 can be connected to an RLC oscillator formed on circuit board 114 to measure the inductance of coil 113. The inductance measurement technique can adopt existing techniques, such as building an RLC oscillator on circuit board 114. Figure 14 The L-shaped oscillation circuit shown in the diagram has L1 as coil 113, and C1 and C2 as resonant capacitors. Adjusting C1 and C2 sets the resonant frequency to approximately 1MHz. This results in an output oscillation frequency of around 1MHz at the "1+" connector position. The oscillation frequency changes with the distance between the nozzle and the coil. Connecting the "1+" connector to a microcontroller with frequency measurement capabilities allows the oscillation frequency to be digitally input into the program. For example... Figure 15 The RLC bridge shown in the figure has its main components as shown in the figure. The detection coil is the coil 113 in this application. This method can simultaneously measure the inductance and resistance of the coil, convert the inductance and resistance into analog voltage signals, and obtain the detection value by the ADC of the microcontroller.

[0205] In some feasible implementations, the eddy current sensor described in this application can be used to detect whether a nozzle is installed. The base for mounting the nozzle in the 3D printer is a metal component, and the cross-sectional area of ​​the metal component facing the eddy current sensor is larger than the cross-sectional area of ​​the nozzle facing the eddy current sensor. For example, when the nozzle is mounted to the metal component, it protrudes from the base. If the nozzle is mounted on the 3D printer, the eddy current sensor first detects the presence of the nozzle. As the distance between the nozzle and the eddy current sensor gradually decreases, the amplitude of the output signal change of the eddy current sensor is small. If the nozzle is not mounted on the 3D printer, the eddy current sensor only detects the presence of the base, i.e., the metal component. As the distance between the base and the eddy current sensor gradually decreases, the amplitude of the output signal change of the eddy current sensor is large. That is, the amplitude of the change in the output signal of the eddy current sensor can be used to determine whether the nozzle is mounted on the 3D printer. For example, the eddy current sensor includes a coil, and the amplitude of the frequency change of the coil can be used to determine whether the nozzle is mounted on the 3D printer. Alternatively, the amplitude of the inductance change of the coil can be used to determine whether the nozzle is mounted on the 3D printer. Optionally, in some feasible implementations, the control tool head is moved to a region away from the eddy current sensor and not above it, and the output frequency A0 of the eddy current sensor is obtained at this time; the control tool head is moved above the eddy current sensor, and the output frequency A1 of the eddy current sensor is obtained at this time. Since the cross-sectional area of ​​the metal part facing the eddy current sensor is larger than the cross-sectional area of ​​the nozzle facing the eddy current sensor, the frequency at which the eddy current sensor detects the nozzle will be lower than the frequency at which it detects the metal part. For example, if the output frequency A1 is greater than a preset threshold, or the difference between the output frequency A1 and the output frequency A0 is greater than a preset threshold, it is determined that the nozzle is not installed on the tool head; if the output frequency A1 is less than a preset threshold, or the difference between the output frequency A1 and the output frequency A0 is less than a preset threshold, it is determined that the nozzle is installed on the tool head.

[0206] To protect the coil, the annular groove 1111 is also filled with adhesive. That is, after the coil 113 is installed in the annular groove 1111, the annular groove is filled with adhesive, and the adhesive forms a protective layer on the surface of the coil 113. In some embodiments, adhesive may also be filled in the wiring groove 1112.

[0207] In some embodiments, the eddy current sensor 110 further includes a protective film 115, which covers the side of the magnetic conductor 111 away from the magnetic generator 112 to protect the coil 113. Specifically, the protective film 115 can be a thin film with adhesive backing, covering the surface of the magnetic conductor 111, thereby protecting the coil 113, especially during nozzle calibration, to prevent the printing material from the nozzle from adhering to the eddy current sensor 110.

[0208] In the above embodiments, the magnetic conductive component 111 may include a ferrite structure. The magnetic generating component 112 includes a permanent magnet or a device capable of generating a magnetic field, such as an energized coil.

[0209] Understandably, the eddy current sensor 110 of this application also includes a housing, on which the magnetic conductor 111, the magnetic generator 112, the coil 113, and the circuit board 114 can all be mounted. The housing can be structured to mate with the magnetic conductor 111, the magnetic generator 112, the coil 113, and the circuit board 114 on the base 120 described below. In this embodiment, the eddy current sensor 110 can be disposed in the printing space via the housing.

[0210] This application also provides a detection component 100 for nozzle calibration of a 3D printer, including a base 120 and an eddy current sensor 110 as described in any of the above embodiments. The eddy current sensor can be mounted entirely on the base 120, or the base can be reused as the housing of the eddy current sensor 110. The magnetic conductive element 111 and the magnetic generating element 112 are directly mounted on the base 110. When the detection component 100 is used for nozzle calibration, the eddy current sensor 110 can be directly placed in the printing space via the base 120. In this embodiment, the eddy current sensor 110 can be placed in the printing space via the base 120. In embodiments where the mounting base 220 is provided with a mounting groove 221, the eddy current sensor 110 can be mounted in the mounting groove 221 via the base 120.

[0211] like Figures 7-12 The base 110 has a sensor groove 121 on its first surface. A magnetic conductor 111 and a magnetic generator 112 are recessed in the sensor groove 121, with the magnetic generator 112 positioned closer to the bottom surface of the sensor groove 121 than the coil 113, thus positioning the coil 113 at the opening of the sensor groove 121. By providing the sensor groove 121, the volume of the detection component can be minimized, which is beneficial for its application in miniaturized 3D printers. Furthermore, this groove structure protects structures such as the coil 113, extending the lifespan of the eddy current sensor. When installing the detection component 100 in the mounting groove 221, it is preferable that the detection component 100 is flush with the printing panel 230.

[0212] In some embodiments, a receiving groove 122 is provided on the second surface of the base 120 opposite to the first surface; the eddy current sensor 110 also includes a circuit board 114, which is mounted in the receiving groove 122; the leads of the coil 113 are electrically connected to the circuit board 114. The receiving groove 122 not only protects the circuit board, especially the components and solder joints thereon, but also further reduces the size of the detection component 100, making it better suited for miniaturized 3D printers.

[0213] Continue to refer to Figure 12 The base 120 has a stepped structure and includes a plate portion 123 and a boss portion 124 connected to one side of the plate portion 123. A sensor groove 121 is disposed on the side of the plate portion 123 facing away from the boss portion 124. A receiving groove 122 is disposed on the boss portion 124. The stepped structure increases the strength of the base 120. In some embodiments, the base 120 can overlap the mounting base 220, that is, the edge area of ​​the plate portion 123 exposed by the boss portion 124 overlaps the mounting base 220. In embodiments with a mounting groove 221, only a portion of the detection component 100 can be located in the mounting groove 221.

[0214] To increase the installation reliability and accuracy of the detection component 100, a limiting fit structure can be provided between the mounting groove 221 and the base 120. For example, a limiting structure can be provided on the side wall of the mounting groove 221, and at least part of the side wall of the base 120 can mate with the limiting structure. The limiting structure includes two opposing protrusions that extend from the opening of the mounting groove 221 to the bottom surface. This protrusion structure increases the strength of the mounting base 220, provides a limiting function, and is easy to manufacture, especially by casting. Alternatively, a positioning structure can be provided on the base 120, including a strip groove that matches the two protrusions. The strip groove can be specifically located on the boss portion. Furthermore, a limiting protrusion can be provided on one of the mounting groove 221 and the base 120, and a limiting groove that mates with the limiting protrusion can be provided on the other.

[0215] In one embodiment, such as Figure 12 As shown, a Z-axis calibration area is also provided on the first surface of the base 120; the detection assembly 100 also includes a Z-axis detection plate 130, which is mounted on the Z-axis calibration area. During Z-axis calibration of the two nozzles, the nozzle 310 contacts the Z-axis detection plate 130. By providing a structure specifically for Z-axis detection, it is possible to prevent the nozzle from contacting other areas of the printing platform, especially in case of ink leakage, which could affect subsequent printing results.

[0216] In a preferred embodiment, the Z-axis calibration area is provided with a receiving groove 125, and the Z-axis detection plate 130 is provided with multiple hollow holes 131, such as... Figure 11 and Figure 12 As shown, the Z-axis detection plate 130 covers the receiving groove 125. By setting the receiving groove 125 and the hollow hole 131, even if wire leaks out when the nozzle 310 touches the Z-axis detection plate 130, it can fall into the receiving groove 125 through the hollow hole 131, so as to avoid the accumulation of wire affecting the calibration accuracy.

[0217] Furthermore, the receiving groove 125 is a stepped groove, and the Z-axis detection plate 130 overlaps the stepped surface 1251 of the stepped groove. By setting the stepped groove, the volume of the detection component can be further reduced.

[0218] The base 120 has a strip-shaped structure, and the Z-axis calibration area and the sensor groove 121 are arranged side by side along the length of the strip-shaped structure. In the embodiment with a plate body, the plate body extends out of the boss portion at both ends along the length of the strip-shaped structure for overlapping.

[0219] It will be understood by those skilled in the art that the above-described preferred solutions can be freely combined and superimposed without conflict. The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings; for example, two consecutively indicated blocks may actually be executed substantially in parallel, or sometimes in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions. The use of step numbers (letter or number) to refer to specific method steps in this application is solely for the purpose of convenience and brevity, and is by no means intended to restrict the order of these method steps. Those skilled in the art will understand that the order of the relevant method steps should be determined by the technology itself and should not be unduly restricted by the existence of step numbers. Those skilled in the art can determine various permissible and reasonable orderings of steps based on the technology itself.

[0220] It should be understood that the above-described embodiments are merely exemplary and not restrictive. Any obvious or equivalent modifications or substitutions made by those skilled in the art regarding the above details without departing from the basic principles of this application shall be included within the scope of the claims of this application.

Claims

1. A nozzle calibration system for a 3D printer, comprising a 3D printer, the 3D printer including a nozzle and a controller, the nozzle being movably disposed in the printing space of the 3D printer; characterized in that, The calibration system further includes an eddy current sensor disposed within the printing space; the controller is used for: The nozzle is controlled to move above the eddy current sensor, and the detection value of the eddy current sensor is collected to obtain the change curve of the detection value in the moving direction; The actual position of the nozzle is determined based on the change curve; The calibration value of the nozzle is determined based on the actual position and the center position of the eddy current sensor.

2. The calibration system according to claim 1, characterized in that, The controller is used to control the nozzle to move along a straight path above the eddy current sensor.

3. The calibration system according to claim 2, characterized in that, The center position of the eddy current sensor includes the X-axis and Y-axis positions of the eddy current sensor in the 3D printer; the controller is used for, The nozzle is controlled to move along a first straight line and a second straight line respectively, and the detection value of the eddy current sensor is collected to obtain a first change curve corresponding to each position on the first straight line and a second change curve corresponding to each position on the second straight line; wherein, the first straight line and the second straight line are parallel to the X-axis and Y-axis of the 3D printer respectively, and the intersection of the two is located in the central region of the eddy current sensor. The actual position of the nozzle on the X-axis is determined based on the first change curve, and the actual position of the nozzle on the Y-axis is determined based on the second change curve; The X-axis calibration value of the nozzle is determined based on the actual position of the X-axis and the X-axis position of the center position, and the Y-axis calibration value of the nozzle is determined based on the actual position of the Y-axis and the Y-axis position of the center position.

4. The calibration system according to claim 2, characterized in that, The controller is used for, The nozzle is controlled to move from the center region of the eddy current sensor, first moving an initial preset distance along the first direction of the straight path; then continuing to move along the second direction of the straight path at a preset step distance to detect a preset distance; and the detection value of the eddy current sensor is collected to obtain the change curve of the detection value along the straight path; Wherein, the first direction is opposite to the second direction.

5. The calibration system according to claim 4, characterized in that, The straight path includes a straight line parallel to the X-axis direction, and the controller obtains the change curve of the detected value in the X-axis direction, thereby obtaining the X-axis calibration value of the nozzle; The straight path includes a straight line parallel to the Y-axis direction. The controller obtains the change curve of the detected value in the Y-axis direction, and then obtains the Y-axis calibration value of the nozzle.

6. The calibration system according to claim 3 or 4, characterized in that, During the acquisition of eddy current sensor detection values, the starting end of at least one straight path of nozzle movement is located at the first end of the eddy current sensor along the straight path or outside the first end of the eddy current sensor.

7. The calibration system according to claim 3 or 4, characterized in that, During the acquisition of eddy current sensor detection values, the termination end of at least one straight path of nozzle movement is located at the second end of the eddy current sensor along the straight path or outside the second end of the eddy current sensor.

8. The calibration system according to claim 1, characterized in that, The actual position of the nozzle is determined based on the peak or trough region of the change curve.

9. The calibration system according to claim 1, characterized in that, The 3D printer is equipped with two nozzles, and the two nozzles are calibrated respectively.

10. The calibration system according to claim 9, characterized in that, The two nozzles include a first nozzle and a second nozzle; Determining the nozzle calibration value based on the actual position and the center position of the eddy current sensor includes: Based on the actual positions of the first nozzle and the second nozzle, the offset of the first nozzle and the second nozzle in the XY plane of the 3D printer is determined.

11. The calibration system according to claim 10, characterized in that, One of the nozzles is closer to the printing platform of the 3D printer on the Z-axis than the other nozzle.

12. The calibration system according to claim 1, characterized in that, The eddy current sensor includes a coil, the maximum dimension of the outer contour of the coil in the straight line passing through its center is 1 to 10 times the diameter of the nozzle opening; the center position of the eddy current sensor is the center position of the coil.

13. The calibration system according to claim 1, characterized in that, The 3D printer also includes a printing platform that is movable relative to the nozzle along the Z-axis, and the eddy current sensor is disposed on the printing platform and located outside the printing area of ​​the printing platform.

14. The calibration system according to claim 13, characterized in that, The eddy current sensor is located on the side wall of the printing platform.

15. The calibration system according to claim 13, characterized in that, The printing platform includes a platform body and a mounting base. The mounting base is connected to the side wall of the platform body and has a mounting groove with the opening of the mounting groove facing the nozzle. The eddy current sensor is mounted in the mounting groove and does not extend beyond the printing plane of the printing platform.

16. The calibration system according to claim 1, characterized in that, The eddy current sensor includes a magnetic conductor, a magnetic generator, and a coil. The magnetic conductor and the magnetic generator are stacked together, and the coil is disposed on the side of the magnetic conductor that faces away from the magnetic generator.

17. The calibration system according to claim 16, characterized in that, The magnetic conductive component has an annular groove on the side facing away from the magnetic generating component; the coil is embedded in the annular groove.

18. The calibration system according to claim 16, characterized in that, The device includes a detection component, which comprises a base and an eddy current sensor. A sensor groove is provided on a first surface of the base. A magnetic conductor and a magnetic generator are mounted in the sensor groove, and the eddy current sensor is disposed in the printing space via the base.

19. The calibration system according to claim 18, characterized in that, The second side of the base is provided with a receiving groove; the eddy current sensor also includes a circuit board, which is mounted in the receiving groove.

20. The calibration system according to claim 18, characterized in that, The printing platform includes a mounting base, which has a mounting groove for mounting the base. A limiting structure is provided on the side wall of the mounting groove, and at least a portion of the side wall of the base cooperates with the limiting structure.

21. The calibration system according to claim 20, characterized in that, The limiting structure includes two opposing protrusions that extend from the opening of the mounting groove to the bottom surface.

22. The calibration system according to claim 18, characterized in that, A Z-axis calibration area is also provided on the first surface of the base; the detection component also includes a Z-axis detection plate, which is installed on the Z-axis calibration area.

23. The calibration system according to claim 22, characterized in that, The Z-axis calibration area is provided with a receiving groove; the Z-axis detection plate is provided with multiple hollow holes, and the Z-axis detection plate covers the receiving groove.

24. The calibration system according to claim 22, characterized in that, The 3D printer has two nozzles, and also includes a printing platform that is movable relative to the nozzles along the Z-axis of the 3D printer; the calibration system further includes a force sensor for detecting whether the nozzles are in contact with the Z-axis detection plate; the controller is also used for: The movement of two nozzles and at least one of the printing platform is controlled respectively. During the relative movement of each nozzle and the printing platform, when the touch signal of the force sensor is detected, the first relative position and the second relative position of the two nozzles and the printing platform in the Z direction are obtained respectively. The offset of the two nozzles in the Z direction is determined based on the first relative position and the second relative position.

25. The calibration system according to claim 14, characterized in that, The eddy current sensor is located on the rear edge of the printing platform and in the middle region of the X-axis direction.

26. The calibration system according to claim 1, characterized in that, The eddy current sensor is detachably mounted to the printing platform.

27. A nozzle calibration method for a 3D printer, the 3D printer comprising a nozzle, the nozzle being movably disposed in the printing space of the 3D printer; characterized in that, An eddy current sensor is also installed within the printing space; the calibration method includes the following steps: S10: Control the nozzle to move above the eddy current sensor and collect the detection value of the eddy current sensor to obtain the change curve of the detection value in the moving direction; S20: Determine the actual position of the nozzle based on the change curve; S30: Determine the calibration value of the nozzle based on the actual position and the center position of the eddy current sensor.

28. The calibration method according to claim 27, characterized in that, In step S10, the nozzle is controlled to move along a straight path above the eddy current sensor.

29. The calibration method according to claim 28, characterized in that, Step 10 includes the following steps: S11: Control the nozzle to move along the first straight line and the second straight line respectively, and collect the detection value of the eddy current sensor to obtain the first change curve corresponding to each position of the detection value on the first straight line and the second change curve corresponding to each position of the second straight line; wherein, the first straight line and the second straight line are parallel to the X-axis and Y-axis of the 3D printer respectively, and the intersection of the two is located in the central region of the eddy current sensor. Step S20 includes the following steps: S21: Determine the actual position of the nozzle on the X-axis based on the first change curve, and determine the actual position of the nozzle on the Y-axis based on the second change curve; Step S30 includes the following steps: S31: Determine the X-axis calibration value of the nozzle based on the actual position of the X-axis and the X-axis position of the center position, and determine the Y-axis calibration value of the nozzle based on the actual position of the Y-axis and the Y-axis position of the center position.

30. The calibration method according to claim 28, characterized in that, Step S10 includes the following steps: S12: Control the nozzle to start from the center region of the eddy current sensor, first move an initial preset distance along the first direction of the straight path; then continue to move along the second direction of the straight path according to a preset step distance to detect a preset distance; and collect the detection value of the eddy current sensor to obtain the change curve of the detection value along the straight path; Wherein, the first direction is opposite to the second direction.

31. The calibration method according to claim 30, characterized in that, The straight path includes a straight line parallel to the X-axis direction, resulting in a curve showing the change of the detected value along the X-axis direction, and thus obtaining the X-axis calibration value of the nozzle; The straight path includes a straight line parallel to the Y-axis direction, resulting in a curve showing the change of the detected value along the Y-axis direction, and thus obtaining the Y-axis calibration value of the nozzle.

32. The calibration method according to claim 31, characterized in that, The preset step distance by which the nozzle moves along the X-axis is equal to the preset step distance by which it moves along the Y-axis; and / or, The preset detection distance by which the nozzle moves along the X-axis is equal to the preset detection distance by which it moves along the Y-axis.

33. The calibration method according to claim 31, characterized in that, Both the initial preset distance and the detection preset distance are related to the outer contour dimensions of the eddy current sensor.

34. The calibration method according to claim 33, characterized in that, The initial preset distance is 0.5 to 1 times the maximum size of the eddy current sensor, wherein the maximum size refers to the maximum size of the outer contour of the coil in the straight line direction passing through its center.

35. The calibration method according to claim 33, characterized in that, The preset detection distance is 0.5 to 2.5 times the maximum size of the eddy current sensor.

36. The calibration method according to claim 31, characterized in that, The preset step size is 0.01 to 0.03 times the maximum size of the eddy current sensor, wherein the maximum size refers to the maximum size of the outer contour of the coil in the straight line direction passing through its center.

37. The calibration method according to claim 29 or 30, characterized in that, In step S10, during the process of acquiring the detection value of the eddy current sensor, the starting end of at least one straight path of the nozzle movement is located at the first end of the eddy current sensor along the straight path or outside the first end of the eddy current sensor.

38. The calibration method according to claim 29 or 30, characterized in that, In step S10, during the process of acquiring the detection value of the eddy current sensor, the termination end of at least one straight path of the nozzle movement is located at the second end of the eddy current sensor along the straight path or outside the second end of the eddy current sensor.

39. The calibration method according to claim 27, characterized in that, In step S20, the actual position of the nozzle is determined based on the peak or trough region of the change curve.

40. The calibration method according to claim 27, characterized in that, The 3D printer is equipped with two nozzles. The two nozzles are controlled to perform steps S10 to S30 respectively to obtain the calibration value of each nozzle.

41. The calibration method according to claim 27, characterized in that, The 3D printer is equipped with a first nozzle and a second nozzle. The two nozzles are controlled to perform steps S10 to S20 respectively to obtain the actual positions of the first nozzle and the second nozzle. Step S30 further includes the following step: S32: Determine the offset of the first nozzle and the second nozzle on the XY plane of the 3D printer based on the actual position of the first nozzle and the actual position of the second nozzle.

42. The calibration method according to claim 1, characterized in that, The 3D printer has two nozzles and also includes a printing platform that is movable relative to the nozzles along the Z-axis of the 3D printer. The 3D printer is further equipped with a force sensor to detect whether the nozzles are in contact with the printing panel. The calibration method also includes the following steps: S50: Control the relative movement of the two nozzles and the printing platform respectively. During the relative movement of each nozzle and the printing platform, when the touch signal of the touch sensor is detected, record the first relative position and the second relative position of the two nozzles and the printing platform in the Z direction. S60: Determine the offset of the two nozzles in the Z direction based on the first relative position and the second relative position.

43. The calibration method according to claim 42, characterized in that, In step S50, during the relative movement of the nozzle and the printing platform, the nozzle is also controlled to be at the printing temperature of the filament.

44. The calibration method according to claim 27, characterized in that, Before performing step S10, the nozzle temperature is also controlled to rise to the printing temperature of the filament.

45. An eddy current sensor for nozzle calibration in a 3D printer, characterized in that, Includes magnetic conductors, magnetic generating components, and coils. The magnetic conductive element and the magnetic generating element are stacked, and the coil is provided on the side of the magnetic conductive element that is away from the magnetic generating element.

46. ​​The eddy current sensor according to claim 45, characterized in that, The magnetic conductive element has an annular groove on the side facing away from the magnetic generating element; the coil is recessed in the annular groove.

47. The eddy current sensor according to claim 46, characterized in that, The magnetic conductor is located in the cylindrical part in the middle of the annular groove to form a positioning and magnetic focusing structure, and the coil is positioned and installed with the positioning and magnetic focusing structure.

48. The eddy current sensor according to claim 46, characterized in that, The magnetic conductive component is also provided with a wiring groove on the side opposite to the magnetic generating component. The wiring groove passes through two opposite sidewalls of the magnetic conductive component and communicates with the annular groove. The coil leads are recessed in the wiring groove and emerge from the two opposite side walls.

49. The eddy current sensor according to claim 48, characterized in that, It also includes a circuit board disposed on the side of the magnetic generating element away from the magnetic conductive element; The wiring channel also extends along two opposite sidewalls to the side of the magnetic conductor near the magnetic generating element and connects to the circuit board.

50. The eddy current sensor according to claim 49, characterized in that, The annular groove is also filled with glue, which forms a protective layer on the surface of the coil.

51. The eddy current sensor according to claim 45, characterized in that, It also includes a protective film that covers the side of the magnetic conductor away from the magnetic generating element to protect the coil.

52. The eddy current sensor according to any one of claims 45-51, characterized in that, The magnetic conductive component includes a ferrite structural component.

53. The eddy current sensor according to any one of claims 45-51, characterized in that, The magnetic generating device includes a permanent magnet or a device capable of generating a magnetic field, and the device capable of generating a magnetic field includes an energized coil.

54. A detection component for nozzle calibration in a 3D printer, characterized in that, The device includes a base and an eddy current sensor as described in any one of claims 28-35, wherein the magnetic conductive element and the magnetic generating element are mounted on the base.

55. The detection component according to claim 54, characterized in that, The first surface of the base is provided with a sensor groove, the magnetic conductor and the magnetic generating element are recessed in the sensor groove, and the magnetic generating element is closer to the bottom surface of the sensor groove than the coil.

56. The detection component according to claim 55, characterized in that, A receiving groove is provided on the second side of the base opposite to the first surface; the eddy current sensor also includes a circuit board, which is mounted in the receiving groove; the leads of the coil are electrically connected to the circuit board.

57. The detection component according to claim 56, characterized in that, The base includes a plate portion and a boss portion connected to one side of the plate portion; the sensor groove is disposed on the side of the plate portion opposite to the boss portion; the receiving groove is disposed on the boss portion.

58. The detection component according to any one of claims 54-57, characterized in that, A Z-axis calibration area is also provided on the first surface of the base; The detection component also includes a Z-axis detection plate, which is installed in the Z-axis calibration area.

59. The detection component according to claim 58, characterized in that, The Z-axis calibration area is provided with a receiving groove; the Z-axis detection plate is provided with multiple hollow holes, and the Z-axis detection plate covers the receiving groove.

60. The detection component according to claim 59, characterized in that, The receiving groove is a stepped groove, and the Z-axis detection plate overlaps the stepped surface of the stepped groove.

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