Print head of 3D printer and 3D printer

Abstract

The present application provides a print head of a 3D printer and a 3D printer. A print head body is provided with an extrusion wheel, a hot end assembly, and a support located between the extrusion wheel and the hot end assembly. The hot end assembly and the support are fixedly connected to the print head body, and the rigidity of the print head body is within a certain range; when the extrusion wheel extrudes a printing material towards the hot end assembly, the print head body deforms, so that the hot end assembly generates displacement relative to the support; a distance sensing device is provided on the side of the support facing the hot end assembly, and the distance sensing device is used for sensing the distance between the hot end assembly and the support, so as to obtain the extrusion force applied by the printing material to the hot end assembly. By implementing the present application, the cost of measuring the extrusion force on the hot end assembly can be reduced, the structure is simple, and the space is compact.

Description

Print head of 3D printer and 3D printer

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 28, 2023, with application number 202322334305.3 and application name “A 3D printer print head and a 3D printer”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of 3D printing technology, and in particular to a print head of a 3D printer and a 3D printer. Background Art

[0003] In a 3D printer, the extruder pushes the printing material toward the hot-end assembly, which exerts an extrusion force on the hot-end assembly. This extrusion force is related to the 3D printer's printing performance, so it is necessary to measure the extrusion force on the hot-end assembly.

[0004] The prior art uses the cantilever surface strain method shown in FIG1 to measure the extrusion force. As shown in FIG1 , the hot end assembly 13 is connected to one end of the strain cantilever 15, and the other end of the strain cantilever 15 is fixed. A strain gauge 14 is attached to the surface of the strain cantilever 15. When the extrusion wheel 11 squeezes the printing material 12 toward the hot end assembly 13, the extrusion force exerted by the printing material 12 on the hot end assembly 13 is transmitted to the strain cantilever 15, causing strain to be generated on the surface of the strain cantilever 15. At this time, the strain of the strain cantilever 15 can be measured by the strain gauge 14, thereby measuring the extrusion force exerted on the hot end assembly 13. Due to the high cost of strain gauges, the prior art method of measuring the extrusion force exerted on the hot end assembly is expensive.

[0005] Summary of the Invention

[0006] The present application provides a 3D printer print head and a 3D printer, which can reduce the cost of measuring the extrusion force exerted on a hot end component, and has a simple structure and a compact space.

[0007] In a first aspect, an embodiment of the present application provides a print head of a 3D printer, wherein the print head body includes an extrusion wheel, a hot end assembly, and a bracket located between the extrusion wheel and the hot end assembly; wherein,

[0008] The hot end assembly and the bracket are fixedly connected to the print head body, and the rigidity of the print head body is within a certain range; when the extrusion wheel squeezes the printing material toward the hot end assembly, the print head body is deformed, causing the hot end assembly to be displaced relative to the bracket;

[0009] The bracket is provided with a distance sensor on a side facing the hot end assembly, and the distance sensor is used to sense the distance between the hot end assembly and the bracket to obtain the extrusion force applied by the printing material to the hot end assembly.

[0010] In the embodiment of the present application, a distance sensing device is added between the bracket and the hot end assembly, and the distance sensing device is used to sense the distance between the hot end assembly and the bracket, thereby obtaining the extrusion force exerted by the printing material on the hot end assembly (i.e., the extrusion force exerted on the hot end assembly). Compared with the cantilever surface strain method in the prior art, the cost of the back-end analog circuit required by the distance sensing device is low. Especially in the scenario where the extrusion force measurement requires a high sampling rate, the cost of the cantilever surface strain method is extremely high. The distance sensing device in the embodiment of the present application has a high bandwidth. Even if the sampling rate is increased, the distance sensing device is still applicable and the cost is relatively low. In addition, the hot end assembly does not need to rely on the cantilever to be connected to the upper-level structure, and has a simple structure, high design flexibility, and high space utilization.

[0011] In combination with the first aspect, in a first possible implementation manner, the hot end assembly is used to contact a printing platform of the 3D printer;

[0012] The distance sensing device is further used to sense multiple distances between the hot end assembly and multiple positions on the printing platform to obtain the flatness of the printing platform.

[0013] In the embodiment of the present application, the flatness of the printing platform can provide data support for the leveling of the printing platform of the 3D printer. That is, by implementing the embodiment of the present application, the extrusion force exerted on the hot end component and the leveling of the printing platform share a distance sensing device, which can further reduce costs.

[0014] In combination with the first aspect or any one of the above possible implementations of the first aspect, in a second possible implementation, the distance sensing device includes a coil, the hot end assembly includes a heat sink fin, and the plane where the coil is located is parallel to the surface of the heat sink fin.

[0015] In the embodiments of the present application, a coil is used to sense the distance between the hot end assembly and the bracket, which is low-cost. Furthermore, the plane of the coil is parallel to the surface of the heat sink fins. As the distance between the hot end assembly and the bracket changes, the reverse induced current generated by the heat sink fins can significantly affect the magnetic field strength of the coil, thereby improving the accuracy of extrusion force measurement.

[0016] In combination with the first aspect or any of the foregoing possible implementations of the first aspect, in a third possible implementation, the hot end assembly includes heat sink fins, and the distance between the distance sensor device and the heat sink fins is less than a sensing distance, where the sensing distance is related to the type of the distance sensor device. Implementing this embodiment of the present application can improve the accuracy of extrusion force measurement.

[0017] In combination with the first aspect or any one of the foregoing possible implementations of the first aspect, in a fourth possible implementation, the distance sensing device includes a coil, and the sensing distance is a diameter of a circumscribed circle of the coil.

[0018] By implementing the embodiment of the present application, by setting the distance between the distance sensor device and the heat dissipation fin to be smaller than the diameter of the circumscribed circle of the coil, the effect of the distance being too large on the measurement is avoided, thereby improving the measurement accuracy.

[0019] In combination with the first aspect or any one of the foregoing possible implementations of the first aspect, in a fifth possible implementation, the distance between the coil and the heat dissipation fin is less than one-fifth of the sensing distance.

[0020] By implementing the embodiment of the present application, the distance between the coil and the heat dissipation fins can be set to be less than one-fifth of the diameter of the circumscribed circle of the coil, which can further improve the detection sensitivity of the distance sensor device and thereby improve the accuracy of measuring distance and extrusion force.

[0021] In combination with the first aspect or any one of the above possible implementations of the first aspect, in a sixth possible implementation, the distance sensing device includes a coil, the hot end assembly includes a heat sink fin, and the winding direction of the coil is parallel to the surface of the heat sink fin.

[0022] By implementing the embodiments of the present application, the magnetic flux of the magnetic field generated by the coil can significantly affect the heat dissipation fins, thereby improving the accuracy of measuring the extrusion force.

[0023] In combination with the first aspect or any one of the above possible implementations of the first aspect, in a seventh possible implementation, the distance sensing device includes a coil, the hot end assembly includes a heat sink fin, and the angle between the plane where the coil is located and the surface of the heat sink fin is an acute angle.

[0024] The implementation of the embodiments of the present application can reduce the size of the coil, lower the cost and reduce the occupied space while adapting to different application scenarios.

[0025] In combination with the first aspect or any one of the foregoing possible implementations of the first aspect, in an eighth possible implementation, the distance sensing device includes a coil, and the hot end assembly includes a heat dissipation fin;

[0026] The print head is further provided with a resonant circuit, which is connected to the coil and is used to output different voltage signals according to the distance between the coil and the heat dissipation fins.

[0027] In the embodiment of the present application, a resonant circuit is used to output different voltage signals, and then the distance between the hot end assembly and the coil is obtained according to the voltage signal, thereby obtaining the extrusion force exerted by the printing material on the hot end assembly.

[0028] In combination with the first aspect or any one of the foregoing possible implementations of the first aspect, in a ninth possible implementation, the distance sensing device includes a coil, and the hot end assembly includes a heat dissipation fin;

[0029] The print head is further provided with a coil detection circuit, which is connected to the coil and is used to measure the inductance and resistance of the coil according to the distance between the coil and the heat sink fin.

[0030] By implementing the embodiments of the present application, a coil detection circuit is used to measure the inductance and resistance of the coil. Then, the distance between the hot end assembly and the coil can be obtained based on the inductance and resistance of the coil, and the extrusion force exerted by the printing material on the hot end assembly can be obtained.

[0031] In a second aspect, an embodiment of the present application provides a 3D printer, comprising a printing platform and a print head as described above in combination with the first aspect or in combination with any possible implementation method; wherein the print head is used to extrude printing material on the printing platform.

[0032] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can be referenced to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of a print head of a 3D printer provided by the prior art;

[0034] FIG2 is a schematic structural diagram of a 3D printer provided in an embodiment of the present application;

[0035] FIG3 is a schematic structural diagram of a print head provided in an embodiment of the present application;

[0036] FIG4 is a schematic diagram of the relative positions between the hot end assembly and the coil according to an embodiment of the present application;

[0037] FIG5 is another schematic diagram of the relative positions between the hot end assembly and the coil provided in an embodiment of the present application;

[0038] FIG6 is a schematic diagram of a coil circumscribed circle provided in an embodiment of the present application;

[0039] FIG7 is a circuit diagram of a resonant circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] The implementation of the technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0041] 2 , which is a schematic diagram of a 3D printer according to an embodiment of the present application, as shown in FIG2 , a 3D printer 102 is connected to a feeding device 101 .

[0042] The feeding device 101 can be used to suspend a material tray with printing material wound around it. The feeding device 101 can provide the printing material to the 3D printer 102, or the printing material can be rewound back to the material tray through the feeding device. In other words, the feeding device can both feed and withdraw material.

[0043] The 3D printer 102 includes a print head 1021, which includes a material guide unit 10211, a hot end assembly 10212, and an extruder wheel disposed between the material guide unit 10211 and the hot end assembly 10212. During material feeding from the feeder 101, the printing material passes through the material guide unit 10211 and then enters the extruder wheel, which delivers the printing material to the hot end assembly 10212. During material withdrawal from the feeder 101, the 3D printer 102 cuts the printing material in the print head 1021, and the extruder wheel delivers the printing material to the feeder 101.

[0044] Optionally, the 3D printer 102 may, for example, cut the printing material between the extrusion wheel and the hot end assembly 10212 or may cut the printing material in the extrusion wheel, etc. This application does not limit the position where the 3D printer cuts the printing material.

[0045] Exemplarily, the 3D printer 102 further includes a printing platform, a base 1025, and a slider 1029. The printing platform may include at least one of a printing panel 1023 and a heated bed 1024. The heated bed 1024 is located on the side of the base 1025a facing the hot end assembly 10212 and has a heating function. The printing panel 1023 is located on the side of the hot bed 1024 facing the hot end assembly 10212. Heat from the hot bed 1024 can be transferred to the printing panel 1023, and the hot end assembly 10212 can extrude molten printing material onto the printing panel 1023.

[0046] In a specific implementation, the 3D printer can adjust the temperature of the hot end assembly 10212 and the hot bed 1024. The temperature of the hot end assembly 10212 is adjusted to heat the printing material to a molten state, and the temperature of the hot bed 1024 is adjusted to adhere the printing material extruded by the hot end assembly 10212 to the printing panel 1023. The print head 1021 is slidably connected to the first guide rail 1026 and can move along the length of the first guide rail 1026, that is, the print head 1021 is displaced relative to the printing panel 1023 along the length of the first guide rail 1026. The hot bed 1024 is slidably connected to the second guide rail 1027 and can move along the length of the second guide rail 1027, that is, the print head 1021 is displaced relative to the printing panel 1023 along the length of the second guide rail 1027. The length of the second guide rail 1027 is perpendicular to the length of the first guide rail 1026. Furthermore, the first guide rail 1026 is slidably connected to the third guide rail 1028. By moving the first guide rail 1026 along the third guide rail 1028, the 3D printer 102 can achieve displacement of the print head 1021 relative to the print panel 1023 in a direction perpendicular to the length of the second guide rail 1027 and in a direction perpendicular to the length of the first guide rail 1026. In other words, the 3D printer 102 can achieve three mutually perpendicular printing paths to print a three-dimensional object.

[0047] In an embodiment of the present application, a distance sensing device is added between the bracket and the hot end assembly. The distance sensing device can sense the distance between the hot end assembly and the bracket to obtain the extrusion force exerted by the printing material on the hot end assembly.

[0048] Referring to Figure 3 , which is a schematic diagram of a print head according to an embodiment of the present invention, a print head body 200 includes an extrusion wheel 201 , a hot end assembly 202 , and a bracket 203 located between the extrusion wheel 201 and the hot end assembly 202 .

[0049] The hot end assembly 202 may include heat sink fins 2021, a nozzle 2023, and a heating unit. The heating unit is used to heat the printing material, which is then molten and extruded from the nozzle 2023. For example, the heat sink fins 2021 can dissipate heat conducted by the heating unit in the hot end assembly 202, preventing the printing material from becoming molten before passing through the heating unit. The heat sink fins 2021 may be made of a metal such as aluminum or iron.

[0050] Optionally, the hot end assembly 202 may further include a silicone sleeve 2022 , which is disposed around the heating unit to prevent heat loss from the heating unit and to prevent a user from being burned when accidentally touching the hot end assembly.

[0051] The hot end assembly 202 and the bracket 203 can be fixedly connected to the print head body 200. Optionally, the print head body 200 can include a print head bracket 206 and an extrusion rear cover 207. The print head bracket 206 can be fixedly connected to the extrusion rear cover 207 and the hot end assembly 202, wherein the hot end assembly 202 can be specifically fixedly connected to a base, and the base is connected to the print head bracket 206 via a fixed axis. The connection involved in this application includes a detachable connection and a non-detachable connection. For example, the fixed connection may include a detachable fixed connection and a non-detachable fixed connection. The extrusion rear cover 207 is fixedly connected to the bracket 203, that is, the bracket 203 is connected to the print head bracket 206 via the extrusion rear cover 207. Exemplarily, the extrusion rear cover 207 and the bracket 203 can be integrally formed.

[0052] The stiffness of the print head body 200 is within a certain range. Stiffness refers to the ability of a material or structure to resist elastic deformation under load. Therefore, the print head body 200 is not completely rigid. When the extrusion wheel 201 squeezes the printing material toward the hot end assembly 202, the nozzle 2023 in the hot end assembly 202 is subjected to the extrusion force, which drives the heat sink fins 2021 away from the extrusion wheel 201, causing the distance between the hot end assembly 202 and the bracket 203 to change.

[0053] In a specific implementation, a distance sensor 204 is provided on the side of the bracket 203 facing the hot-end assembly 202. Specifically, the distance sensor 204 is located between the bracket 203 and the hot-end assembly 202. The distance sensor 204 can be used to sense the distance between the hot-end assembly 202 and the bracket 203. This distance is correlated with the extrusion force exerted by the printing material on the hot-end assembly. Once the distance between the hot-end assembly 202 and the bracket 203 is determined, the extrusion force exerted by the printing material on the hot-end assembly 202 can be calculated by converting this distance into extrusion force, which is the extrusion force exerted on the nozzle 2023.

[0054] In the embodiment of the present application, a distance sensing device is added between the bracket and the hot end assembly, and the distance sensing device is used to sense the distance between the hot end assembly and the bracket, thereby obtaining the extrusion force exerted by the printing material on the hot end assembly (i.e., the extrusion force exerted on the hot end assembly). Compared with the cantilever surface strain method in the prior art, the cost of the back-end analog circuit required by the distance sensing device is low. Especially in the scenario where the extrusion force measurement requires a high sampling rate, the cost of the cantilever surface strain method is extremely high. The distance sensing device in the embodiment of the present application has a high bandwidth. Even if the sampling rate is increased, the distance sensing device is still applicable and the cost is relatively low. In addition, the hot end assembly does not need to rely on the cantilever to be connected to the upper-level structure, and has a simple structure, high design flexibility, and high space utilization.

[0055] In some feasible embodiments, the distance sensing device 204 may include a coil. When the distance between the hot end assembly 202 and the bracket 203 changes, the distance between the hot end assembly 202 and the coil also changes, causing the coil's equivalent inductance to change. For example, when the distance between the hot end assembly 202 and the coil increases, the coil's equivalent inductance decreases. The distance between the hot end assembly 202 and the coil can be measured by measuring the coil's equivalent inductance, thereby determining the extrusion force exerted by the printing material on the hot end assembly 202. By using only one coil to measure the extrusion force, the space and material costs required for extrusion force measurement are reduced. Furthermore, because the coil lacks a filtering circuit, the coil-based distance measurement has a high bandwidth, sampling rate, and refresh rate, making it suitable for high-sampling-rate scenarios and improving the accuracy of extrusion force measurement.

[0056] Optionally, the inductance of the coil may be 20 μH. The inductance of the coil is related to the self-inductance capability of the inductor. A better inductance can improve the ability to sense distance changes.

[0057] The distance sensor 204 senses the distance between the hot end assembly 202 and the bracket 203, specifically, the distance between the heat sink fins 2021 in the hot end assembly 202 and the bracket 203. When the distance sensor 204 includes a coil, the distance between the heat sink fins 2021 in the hot end assembly 202 and the coil on the bracket 203 is sensed.

[0058] Furthermore, in some feasible embodiments, referring to FIG. 4 , FIG. 4 is a schematic diagram of the relative positions between the hot-end assembly and the coil according to an embodiment of the present application. As shown in FIG. 4 , the plane of the coil 3041 is parallel to the surface of the heat sink fins 3021. In a specific implementation, when the distance between the hot-end assembly and the bracket decreases, due to the oscillating current in the coil 3041, according to Lenz's law, the heat sink fins 3021 will generate a reverse induced current. This reverse induced current reduces the magnetic flux passing through the coil 3041, that is, the equivalent inductance of the coil 3041 decreases, and the resonant frequency of the coil 3041 increases. For another example, when the distance between the hot-end assembly and the bracket increases, the reverse induced current generated by the heat sink fins 3021 increases the magnetic flux passing through the coil 3041, that is, the equivalent inductance of the coil 3041 increases, and the resonant frequency of the coil 3041 decreases. In other words, there is a correlation between the distance between the hot-end assembly and the bracket and the resonant frequency of the coil 3041. When the plane where the coil 3041 is located is parallel to the surface of the heat sink fin 3021, the reverse magnetic field corresponding to the reverse induced current generated by the heat sink fin 3021 is perpendicular to the plane where the coil 3041 is located. The number of magnetic flux lines in the reverse magnetic field passing through the coil is large, and the coil sensing sensitivity is high, thereby improving the accuracy of measuring the extrusion force.

[0059] Optionally, in some feasible implementations, the winding direction of the coil 3041 is parallel to the surface of the heat sink 3021. In this case, the magnetic flux of the magnetic field generated by the coil can greatly affect the heat sink, thereby improving the accuracy of measuring the extrusion force.

[0060] Alternatively, in some feasible embodiments, Figure 5 illustrates another schematic diagram of the relative positions of the hot end assembly and the coils provided in an embodiment of the present application. As shown in Figure 5 , the angle between the plane of coil 4041 and the surface of heat sink fins 4021 can be acute. This allows for greater flexibility in the placement of coil 4041, allowing for a wider range of application scenarios.

[0061] In some feasible embodiments, the distance between the distance sensor device and the heat sink fins can be less than the sensing distance, which can be related to the type of distance sensor device. If the plane on which the distance sensor device is located forms an acute angle with the heat sink fins, the distance between the distance sensor device and the heat sink fins can be the maximum distance between the distance sensor device and the heat sink fins. Because different types of distance sensors have different sensing distances, by setting the distance between the distance sensor device and the heat sink fins to be less than the sensing distance, the distance sensor device can ensure that it can perform its measurement function and avoid the distance being too far away from the distance sensor device and making it unable to measure.

[0062] For example, the distance sensing device may be an eddy current sensor, and the distance sensing device may include a coil. In this case, the sensing distance of the distance sensing device may be the diameter of the circumscribed circle of the coil. As shown in FIG6 , taking the coil as a square as an example, assuming that the size of the coil is 10 mm*10 mm, the diameter of the circumscribed circle of the coil is

[0063] In some feasible embodiments, the distance between the coil and the heat sink fins can be less than one-fifth of the sensing distance. For example, the distance between the coil and the heat sink fins is less than one-fifth of the diameter of the coil's circumcircle. The inventors of this application have found in practice that setting the distance between the coil and the heat sink fins to less than one-fifth of the diameter of the coil's circumcircle results in higher sensitivity and better accuracy in measuring extrusion force.

[0064] In some feasible implementations, see Figure 7, which is a circuit diagram of a resonant circuit provided in an embodiment of the present application. As shown in Figure 7, the printhead further includes a resonant circuit connected to a coil. Because the coil's equivalent inductance varies with the distance between the hot end assembly and the bracket, the resonant circuit outputs voltage signals of varying frequencies.

[0065] In a specific implementation, the resonant circuit may include a first capacitor C1, a second capacitor C2, a third capacitor C3, a first resistor R1, a second resistor R2, and a third resistor R3, wherein the first capacitor C1 and the second capacitor C2 are resonant capacitors. For example, by adjusting the capacitance values ​​of the first capacitor C1 and the second capacitor C2 to set the resonant frequency to about 1 MHz, a voltage signal having an oscillation frequency of about 1 MHz and varying with the distance between the coil and the heat sink fins can be output at Out+, and by connecting the Out+ connector to a controller with a frequency measurement function, the oscillation frequency can be digitally input into the program on the controller. Through the calculation of the controller, the distance between the hot end assembly and the bracket can be obtained, and the extrusion force exerted by the printing material on the hot end assembly can be obtained by converting the distance into the extrusion force.

[0066] In an embodiment of the present application, a resonant circuit is used to output different voltage signals, and then the distance between the hot end assembly and the coil is obtained based on the voltage signal, thereby obtaining the extrusion force exerted by the printing material on the hot end assembly, thereby realizing the distance sensing process.

[0067] Optionally, in some feasible embodiments, the print head may further include a coil detection circuit connected to the coil. Because the coil's equivalent inductance varies with the distance between the hot end assembly and the bracket, the coil's inductance and resistance also vary with the distance between the hot end assembly and the bracket. Therefore, the coil detection circuit can convert the coil's inductance and resistance into analog voltage signals. A controller collects these analog voltage signals to obtain the coil's inductance and resistance, and then determines the distance between the hot end assembly and the bracket based on the coil's inductance and resistance.

[0068] In an embodiment of the present application, a coil detection circuit is used to measure the inductance and resistance of the coil. Then, the distance between the hot end assembly and the coil can be obtained based on the inductance and resistance of the coil, and the extrusion force exerted by the printing material on the hot end assembly can be obtained, thereby realizing the distance sensing process.

[0069] Optionally, in some feasible embodiments, the nozzle in the hot end assembly can contact the printing platform of the 3D printer, and the distance sensing device is also used to sense multiple distances between the hot end assembly and multiple positions in the printing platform to obtain the flatness of the printing platform.

[0070] For example, the print head may also be provided with a leveling detection circuit, which may be connected to a distance sensor device that may output different signals according to the distance between the coil and the heat sink fins, thereby obtaining the flatness of the printing platform.

[0071] In one example, the distance sensing device is a coil, and the leveling detection circuit can be connected in parallel with the extrusion force detection circuit (such as the resonant circuit and coil detection circuit mentioned above), and the leveling detection circuit can also share the same circuit with the extrusion force detection circuit.

[0072] In the embodiment of the present application, the flatness of the printing platform can provide data support for the leveling of the printing platform of the 3D printer. That is, by implementing the embodiment of the present application, the extrusion force exerted on the hot end component and the leveling of the printing platform share a distance sensing device, which can further reduce costs.

[0073] It should be noted that the above terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

Claims

1. A print head for a 3D printer, characterized in that: The print head body is provided with an extrusion wheel, a hot end assembly and a bracket located between the extrusion wheel and the hot end assembly; wherein, The hot end assembly and the bracket are fixedly connected to the print head body, and the rigidity of the print head body is within a certain range; The bracket is provided with a distance sensor on a side facing the hot end assembly.

2. The print head according to claim 1, characterized in that: The hot end assembly is used to contact the printing platform of the 3D printer; The distance sensing device is also used to sense multiple distances between the hot end assembly and multiple positions in the printing platform to obtain the flatness of the printing platform.

3. The print head according to any one of claims 1 to 2, characterized in that: The distance sensor device includes a coil, the hot end component includes a heat sink fin, and the plane where the coil is located is parallel to the surface of the heat sink fin.

4. The print head according to any one of claims 1 to 3, characterized in that: The hot end assembly includes heat dissipation fins, and the distance between the distance sensor device and the heat dissipation fins is less than a sensing distance, and the sensing distance is related to the type of the distance sensor device.

5. The print head according to claim 4, characterized in that: The distance sensing device comprises a coil, and the sensing distance is the diameter of a circumscribed circle of the coil.

6. The print head according to claim 5, characterized in that: The distance between the coil and the heat dissipation fin is less than one fifth of the sensing distance.

7. The print head according to any one of claims 1 to 6, characterized in that: The distance sensor device comprises a coil, the hot end assembly comprises a heat sink fin, and the winding direction of the coil is parallel to the surface of the heat sink fin.

8. The print head according to any one of claims 1 to 2, characterized in that: The distance sensor device includes a coil, the hot end component includes a heat dissipation fin, and the angle between the plane where the coil is located and the surface of the heat dissipation fin is an acute angle.

9. The print head according to any one of claims 1 to 8, characterized in that: The distance sensor device includes a coil, and the hot end component includes a heat dissipation fin; The print head is further provided with a resonant circuit, the resonant circuit is connected to the coil, and the resonant circuit is used to output a voltage signal according to the distance between the coil and the heat sink fin.

10. The print head according to any one of claims 1 to 8, characterized in that: The distance sensor device includes a coil, and the hot end assembly includes a heat sink fin; The print head is further provided with a coil detection circuit, which is connected to the coil and is used to measure the inductance and resistance of the coil according to the distance between the coil and the heat sink fin.

11. The print head according to any one of claims 1 to 10, characterized in that: The distance sensing device is used to sense the distance between the hot end assembly and the bracket to obtain the extrusion force applied by the printing material to the hot end assembly.

12. A 3D printer, characterized in that: The 3D printer comprises a printing platform and a print head as claimed in any one of claims 1 to 11; wherein the print head is used to extrude printing material on the printing platform.

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