Thermal expansion dynamic compensation method and system and high-temperature 3D printer

Abstract

The invention relates to the technical field of additive manufacturing, and discloses a thermal expansion dynamic compensation method and system and a high-temperature 3D printer, and the method comprises the steps that the real-time temperature of each thermal expansion sensitive area is measured through N temperature sensors arranged on the 3D printer; a coefficient vector obtained through pre-calculation is substituted into the mapping relation formula, and thermal expansion displacement between the spray head and the printing platform under the current temperature condition is obtained through calculation; and based on the thermal expansion displacement, the real-time distance between the spray head and the printing platform is compensated, so that the compensated distance is consistent with the initial distance. The method further comprises the steps that a high-temperature-resistant distance sensor is used, and a data set of the temperature-thermal expansion displacement mapping relation is measured in advance; and calculating to obtain a coefficient vector in a temperature-thermal expansion displacement mapping relation formula corresponding to each temperature sensor. The Z-axis thermal expansion displacement is dynamically compensated, and the problem of nozzle height deviation caused by thermal deformation in high-temperature printing is solved.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing technology. Specifically, it relates to a method and system for dynamic thermal expansion compensation and a high-temperature 3D printer. Background Art

[0002] In recent years, 3D printing technology has developed rapidly. Especially in the field of high-temperature 3D printers, the application of high-precision and high-performance materials has promoted the popularization of high-temperature 3D printers. High-temperature 3D printers use a special nozzle and heating system to heat thermoplastic materials (such as plastic filaments) to a molten state of about 500°C, and then extrude them layer by layer through the nozzle onto the printing platform, depositing materials along the preset path to construct a three-dimensional object layer by layer. In addition, a constant-temperature chamber is equipped in the high-temperature 3D printer. The chamber can be heated up to 300°C at most. The chamber temperature is maintained at a relatively high level, which helps to provide a stable thermal environment and can significantly reduce the shrinkage and warping of materials during the cooling process. Different from traditional 3D printing technology, high-temperature 3D printers can use high-temperature-resistant materials, such as high-temperature polymers and metals, to print high-strength and heat-resistant parts, showing great potential in the fields of aerospace, medical devices, and industrial manufacturing.

[0003] However, with the increase in printing temperature, the problem of thermal expansion of the internal structure of the printer becomes increasingly prominent. For example, during the high-temperature fused deposition modeling (FDM) printing process, the structural components of the printer (such as the frame, motion system, hot end assembly, etc.) will undergo thermal expansion due to long-term exposure to a high-temperature environment. Metal linear guides, lead screws, and frames may produce deformations of dozens to hundreds of micrometers when the temperature rises. This deformation directly causes a change in the initial calibration distance between the printing nozzle and the platform. Specifically, it is manifested as follows: the nozzle height is normal at the beginning of printing, but as the temperature of the heated bed and the hot end increases, the structure expands, causing the nozzle to gradually approach the platform, which may result in excessive extrusion pressure, material accumulation, and even nozzle scratching of the platform; conversely, if the expansion direction of the frame is opposite, it may cause the nozzle to move away from the platform, leading to poor adhesion of the first layer. For high-precision printing, this error at the micron level is sufficient to seriously affect the printing quality. Summary of the Invention

[0004] In order to solve the above technical problems, this application discloses a method and system for dynamic thermal expansion compensation and a high-temperature 3D printer. By real-time monitoring the temperature field distribution of key parts, combining offline calibration data with an online parameter update algorithm, it dynamically compensates for the thermal expansion displacement of the Z-axis, solves the problem of nozzle height deviation caused by thermal deformation during high-temperature printing, and realizes a more stable and low-cost real-time dynamic compensation technology to improve the reliability of Z-axis correction. Specifically, the technical solution of this application is as follows:

[0005] In a first aspect, the present application discloses a thermal expansion dynamic compensation method for a high-temperature 3D printer, including the following steps:

[0006] Measure the real-time temperature of each thermal expansion sensitive area through N temperature sensors arranged on the 3D printer;

[0007] Substitute the pre-calculated coefficient vector into the mapping relation formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition; wherein, the coefficient vector is obtained by offline calibrating the mapping relation of temperature-thermal expansion displacement and fitting by the least square method;

[0008] Based on the thermal expansion displacement, compensate the real-time distance between the nozzle and the printing platform so that the compensated distance is consistent with the initial distance.

[0009] In some embodiments, the thermal expansion dynamic compensation method for a high-temperature 3D printer further includes: using a high-temperature resistant distance sensor to pre-determine the data set of the mapping relation of temperature-thermal expansion displacement; so as to calculate the coefficient vector in the mapping relation formula of temperature-thermal expansion displacement corresponding to each temperature sensor.

[0010] In some embodiments, the using a high-temperature resistant distance sensor to pre-determine the data set of the mapping relation of temperature-thermal expansion displacement specifically includes:

[0011] Obtain the temperature values of N sensors at a certain moment; at the same time, use a high-temperature resistant distance sensor to measure the measured distance between the nozzle and the printing platform;

[0012] Based on the measured distance and the initial distance, calculate the thermal expansion displacement ΔZ;

[0013] Repeat the test M times to calibrate the data set of the mapping relation of temperature-thermal expansion displacement: {(t1, t2, t3... t n ), ΔZ};

[0014] wherein, t n is the measured temperature of the nth temperature sensor, and ΔZ is the thermal expansion displacement.

[0015] In some embodiments, the thermal expansion dynamic compensation method for a high-temperature 3D printer further includes:

[0016] Designate the temperature sensor in the specified constant temperature chamber as the reference sensor;

[0017] Based on the temperature value measured by the reference sensor, use a high-temperature resistant distance sensor to perform temperature-thermal expansion displacement measurement at preset temperature intervals within the specified temperature measurement range.

[0018] In some embodiments, calculating the coefficient vector in the mapping relationship formula of temperature-thermal expansion displacement corresponding to each of the temperature sensors; specifically including:

[0019] Establishing a first temperature parameter matrix T of the temperature sensor and a thermal expansion displacement matrix Y;

[0020]

[0021] Y = [ΔZ1, ΔZ2, ΔZ3, … ΔZ m T ;

[0022] where t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the measured temperature of the first temperature sensor in the first test sample; t nm is the measured temperature of the nth temperature sensor in the mth test sample; ΔZ m is the thermal expansion displacement measured in the mth test sample;

[0023] Based on the first temperature parameter matrix and the mapping relationship of temperature-thermal expansion displacement, constructing a first coefficient vector equation W1:

[0024] w1 = [ω1, ω2... ω n

[0025] w1 = ((T - t0) T (T - t0)) -1 (T - t0) T Y;

[0026] where T is the first temperature parameter matrix, t0 is the initial ambient temperature; Y is the thermal expansion displacement matrix;

[0027] Calculating the linear term coefficient ω corresponding to each of the temperature sensors in the first mapping relationship formula by the least squares method i , i ∈ 1 ~ n.

[0028] Based on this embodiment, substituting the pre-calculated coefficient vector into the mapping relationship formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition; specifically including:

[0029] Obtaining the current real-time temperature;

[0030] Substituting the linear term coefficient ω corresponding to each of the temperature sensors into the following first mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under the real-time temperature condition:​​

[0031]

[0032] Among them, ω i is the linear term coefficient corresponding to the i-th sensor; t i is the real-time temperature measured by the i-th temperature sensor; t0 is the initial ambient temperature; ε is the error term.

[0033] In some embodiments, calculating the coefficient vector in the mapping relationship formula of the temperature-thermal expansion displacement corresponding to each of the temperature sensors; specifically including:

[0034] Considering the non-linearity of thermal expansion, establishing the second temperature parameter matrix T of the temperature sensor and the thermal expansion displacement matrix Y;

[0035]

[0036] Y = [ΔZ1, ΔZ2, ΔZ3, … ΔZ m T ;

[0037] Among them, t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the measured temperature of the first temperature sensor in the first test sample; t nm is the measured temperature of the n-th temperature sensor in the m-th test sample; ΔZ m is the thermal expansion displacement measured in the m-th test sample;

[0038] Based on the second temperature parameter matrix and the mapping relationship of temperature-thermal expansion displacement, constructing the second coefficient vector equation W2:

[0039] w2 = [ω1, ω2... ω n , β1, β2... β n T ;

[0040] w2 = (T T T) -1 T T Y;

[0041] Among them, T is the second temperature parameter matrix and Y is the thermal expansion displacement matrix;

[0042] Calculating the linear term coefficient ω i and the quadratic term coefficient β i corresponding to each of the temperature sensors through the least squares method, where i ∈ 1 to n.

[0043] ​​Preferably, in matrix solving, if the matrix is close to a singular matrix, the singular value decomposition method is used for calculation.

[0044] Based on the present embodiment, substituting the pre-calculated coefficient vector into the mapping relationship formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition; specifically including:

[0045] Obtain the current real-time temperature;

[0046] Substitute the linear term coefficient ω corresponding to each temperature sensor i and the quadratic term coefficient β i into the following second mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under the real-time temperature condition:

[0047]

[0048] where ω i is the linear term coefficient corresponding to the i-th sensor; t i is the real-time temperature measured by the i-th temperature sensor; t0 is the initial ambient temperature; and ε is the error term.

[0049] In a second aspect, the present application also discloses a thermal expansion dynamic compensation system for a high-temperature 3D printer, including a memory, a processor, and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the method in any of the above embodiments.

[0050] In a third aspect, the present application also discloses a high-temperature 3D printer, where temperature sensors are respectively arranged at N thermal expansion sensitive areas on the high-temperature 3D printer; and it is further equipped with a thermal expansion dynamic compensation system for a high-temperature 3D printer as described in the above embodiment.

[0051] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0052] 1. By integrating the temperature sensor and the thermal expansion displacement mapping relationship formula to construct a dynamic compensation system, the present application can significantly improve the stability and reliability of the Z-axis correction of the high-temperature 3D printer. By using the temperature sensor to real-time monitor the temperature distribution of the thermal expansion sensitive areas (nozzle assembly, XYZ-axis motion assembly, frame, platform) of the printer, and combining with the coefficient vector in the mapping relationship formula, the thermal deformation amount can be calculated in real time and the Z-axis offset can be dynamically adjusted. It effectively solves the problem that the traditional leveling technology cannot cope with the continuous thermal expansion during the printing process.

[0053] 2. This application has a relatively low cost, is easy to promote, and features low hardware dependence. This application only uses high-temperature resistant distance sensors or laser interferometers, etc. during the pre-calibration stage to establish the reference mapping relationship between temperature and displacement. During specific use, it only relies on low-cost temperature sensors to collect real-time temperature data, and does not require high-value high-temperature resistant ranging sensors during specific use. High-precision compensation can be achieved only through algorithms, avoiding the cost of expensive high-temperature resistant ranging probes. In addition, through real-time data processing at the software level, the mechanical structure transformation cost can be further reduced.

[0054] 3. This application takes into account that the print head and frame in the device are usually composed of different materials, and the difference in the thermal expansion coefficients of each material will cause non-linear deformation. Therefore, the compensation parameters are optimized online by the least squares method to adapt to material and environmental changes, making the compensation algorithm more accurate. Furthermore, the success rate of the first-layer printing of the 3D printer is improved, and the unattended operation ability of the device is enhanced.

[0055] 4. Based on the thermal expansion compensation method of this application, the thermal equilibrium waiting time is shortened from 2 - 4 hours to 10 - 15 minutes. There is no need to wait for the device to reach thermal equilibrium (from low temperature to thermal equilibrium), and printing can be started immediately after the heated bed reaches the required temperature (to ensure the adhesion of the first-layer model during the heating of the heated bed). It can significantly reduce the printing failure rate, reduce material waste, and at the same time improve the dimensional accuracy of the formed parts, providing a more reliable additive manufacturing solution for high-end fields such as aerospace and medical implants. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The above characteristics, technical features, advantages and their implementation manners of this application will be further described below in a clear and understandable manner in combination with the drawings in the preferred embodiments.

[0057] Figure 1 It is a flowchart of the steps of an embodiment of the thermal expansion dynamic compensation method for a high-temperature 3D printer of this application;

[0058] Figure 2 It is a schematic diagram of the distribution of temperature sensors on a high-temperature 3D printer device of this application;

[0059] Figure 3 It is a flowchart of the steps of another embodiment of the thermal expansion dynamic compensation method for a high-temperature 3D printer of this application;

[0060] Figure 4 It is a structural block diagram of an embodiment of the thermal expansion dynamic compensation system for a high-temperature 3D printer of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] In the following description, specific details such as specific system architectures, technologies, etc. are presented for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0062] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0063] To make the drawings concise, only the parts related to the invention are schematically shown in each drawing, and they do not represent the actual structure of the product. Additionally, to make the drawings concise and easy to understand, for components with the same structure or function in some drawings, only one of them is schematically shown, or only one of them is labeled. In this document, "one" not only means "only this one" but also can mean "more than one" situation.

[0064] It should also be further understood that the term "and / or" used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0065] In addition, in the description of the present application, the terms "first", "second", etc. are only used for differentiating descriptions and cannot be understood as indicating or implying relative importance.

[0066] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will describe the specific embodiments of the present application with reference to the accompanying drawings. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, and other embodiments can also be obtained.

[0067] In recent years, 3D printing technology has developed rapidly and has been widely used in aerospace, automobile manufacturing, medical implants, architectural models and consumer goods manufacturing. With the advancement of materials science and printing technology, 3D printing technology has gradually expanded from early photo-curing (SLA) and fused deposition modeling (FDM) to high-end manufacturing technologies such as selective laser sintering (SLS), electron beam melting (EBM) and direct metal laser sintering (DMLS). In particular, the emergence of high-temperature 3D printers has enabled high-performance materials such as PEEK, ULTEM, PEKK, metal alloys and ceramics to be used in the manufacture of parts in extreme environments, such as aircraft engine parts, high-temperature molds and corrosion-resistant chemical equipment. However, during high-temperature 3D printing, the printing temperature usually needs to be maintained at 300°C, and the material will undergo significant volume expansion during the heating process due to the high coefficient of thermal expansion (CTE). During printing, the distance from the printing nozzle to the platform will continue to change, affecting the printing effect of the first layer, and often causing printing failure. The existing technology lacks the ability of real-time dynamic compensation and cannot be applied to temperature fluctuations from low temperature to thermal equilibrium.

[0068] Taking fused deposition modeling (FDM) printing as an example, during the FDM 3D printing process, the print nozzle and the print platform will undergo thermal expansion when heated, resulting in an increase in the actual distance between the two, which in turn has a significant impact on the printing quality. First, the increase in the distance between the nozzle and the platform will cause the first layer of printing height to deviate from the preset value, resulting in the material being unable to fully fit the platform after extrusion, causing insufficient adhesion, and even causing warping or prints to fall off. Secondly, the Z-axis offset caused by thermal expansion will accumulate layer by layer, causing height errors in subsequent printing layers, affecting dimensional accuracy and surface flatness. In addition, if the thermal expansion is uneven (such as local deformation of the platform due to heat), it may also cause the print head to collide with the formed part, which can easily lead to failure of adhesion of the first layer, misalignment between layers, or even overall printing collapse and printing failure.

[0069] At present, the most common approach to the thermal expansion problem is to wait for the chamber temperature to rise to the specified temperature, keep it warm for a period of time, wait for the chamber to reach thermal equilibrium, and then perform the leveling printing operation. However, this will still encounter the following problems, such as: 1. Thermal balance dependence problem: It is necessary to wait for the chamber to be completely thermally balanced (2-4 hours) before leveling. 2. Safety hazards: Manual leveling in a high temperature environment can easily cause burns to the operator (the heat wave of the chamber temperature and the contact surface temperature can reach 250℃+, and there is a serious risk of burns). 3. Poor material adaptability: Different materials (ABS 90℃ / PEEK 300℃) require repeated leveling processes. 4. Low efficiency in winter: Low ambient temperature causes the thermal balance time to be extended by 30% to 50%.

[0070] In some existing technical means, temperature control in a constant-temperature environment and other technical means can also be adopted in the prior art to address the thermal expansion problem. For example, a preheated printing platform or a closed constant-temperature chamber can be used to control thermal expansion through heat insulation. However, these methods still have limitations. For example, in a closed constant-temperature chamber, although the heating chamber is isolated from the motion system, the nozzle assembly is still between the chamber and the motion assembly, and true heat insulation cannot be achieved. Moreover, the temperature is easily conducted to the motion assembly, resulting in thermal expansion problems in the motion assembly and the like.

[0071] To solve the above technical problems, this application adopts the technical means of Z-axis automatic correction and compensation, aiming to maintain a stable printing distance. In the specific implementation process, the Z-axis automatic correction and compensation technology mainly relies on sensor feedback and software compensation. Common sensor solutions include laser rangefinders, mechanical limit switches, and capacitive / inductive contact probes. The sensor adjusts the thermal expansion displacement by measuring the distance between the nozzle and the printing platform. However, in a 3D printer, high-temperature-resistant ranging sensors are usually expensive, and it is impossible to equip every 3D printer with a high-temperature-resistant ranging sensor to save costs. Moreover, there is a certain lag in the process of software compensation after ranging, and it is impossible to correct the dynamic deformation during the printing process in real time.

[0072] Based on this, this application proposes a dynamic thermal compensation method for the nozzle height of a high-temperature 3D printer based on multi-sensor fusion. By real-time monitoring the temperature field distribution of key parts, combining offline calibration data with an online parameter update algorithm, it dynamically compensates for the Z-axis thermal expansion displacement, solves the problem of nozzle height deviation caused by thermal deformation during high-temperature printing, and is applicable to the stable forming of high-melting-point materials such as PEEK, PEI, ULTEM, and PEKK, as well as improving printing efficiency.

[0073] Refer to the attached Figure 1 As shown in the specification, Embodiment 1 of the thermal expansion dynamic compensation method for a high-temperature 3D printer in this application specifically includes the following steps:

[0074] S100, measure the real-time temperature of each thermal expansion sensitive area through N temperature sensors set on the 3D printer.

[0075] S200, substitute the pre-calculated coefficient vector into the mapping relation formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition. Among them, the coefficient vector is obtained by calibrating the temperature-thermal expansion displacement mapping relation offline and fitting it by the least squares method.

[0076] S300, based on the thermal expansion displacement, compensate the real-time distance between the nozzle and the printing platform so that the compensated distance is consistent with the initial distance.

[0077] Specifically, the thermal expansion sensitive areas usually include key positions such as the XYZ carbon steel crossbeam, the nozzle base, the printing platform, and the heat preservation cavity.

[0078] Optionally, in an implementation manner of this embodiment, refer to the attached drawings of the specification. Figure 2 As shown, the red marked points of the 3D printer in this embodiment are the thermal expansion sensitive areas in this embodiment, that is, the sensor arrangement. In this embodiment, the sensor selects a high-precision temperature sensor, such as a PT100 temperature sensor (accuracy ±0.5°C), in order to construct a temperature field distribution and thermal expansion displacement data model.

[0079] Among them, the N temperature sensors are respectively distributed at the following positions, including:

[0080] a. The XYZ carbon steel crossbeam; it has a large thermal expansion coefficient, is easy to conduct heat, and has significant deformation. The carbon steel part; has a large specific heat capacity and is easily affected by thermal deformation. b. The nozzle assembly; such as the nozzle base plate, which is close to the bellows cover and is directly affected by high temperature, and has a direct impact on the Z-direction displacement of the nozzle. c. The printing platform column; is affected by the heating of the heating bed and the temperature of the cavity. d. The heat preservation cavity; is used to monitor the overall temperature field distribution. e. The frame column near the heat preservation cavity; the temperature rise of the frame column directly affects the Z-direction height of the nozzle.

[0081] The N temperature sensors realize synchronous acquisition of sensor signals through a multi-channel data acquisition system to ensure the time-domain consistency of temperature data at each position.

[0082] In another implementation manner of this embodiment, the sensors are arranged at the parts that have a greater impact on the Z-direction height of the nozzle and the thermal expansion sensitive areas. These sensitive positions can also be obtained by means of finite element analysis and experiments. This application does not specifically limit the position and distribution of the sensors, and those skilled in the art should be able to set the sensor positions according to the actual situation of the 3D printer and the test data.

[0083] Preferably, the number N of temperature sensors is taken as 6 - 15 groups. The more the number of temperature sensors, the higher the accuracy of temperature field modeling, and the greater the corresponding calculation amount.

[0084] In this embodiment, it is expected to pre-determine the coefficient vector and the mapping relationship formula. During specific use, it only depends on low-cost temperature sensors to collect temperature data in real time, and then the thermal deformation amount can be calculated in real time and the Z-axis offset can be dynamically adjusted. Solve the problem of nozzle height offset caused by thermal deformation during high-temperature printing.

[0085] In addition, during specific use, there is no need to equip high-value high-temperature-resistant ranging sensors. Only through temperature sensors and algorithms can high-precision compensation be achieved, avoiding the cost of expensive high-temperature-resistant ranging probes. Through real-time data processing at the software level, the mechanical structure transformation cost can be further reduced.

[0086] Based on this embodiment, referring to the appended drawings of the specification Figure 3 , before implementing the thermal expansion dynamic compensation method of the high-temperature 3D printer of the present application, it is also necessary to pre-determine the mapping relationship formula and the coefficient vector therein. The specific steps are as follows:

[0087] S010. Use a high-temperature resistant distance sensor to pre-determine the dataset of the temperature-thermal expansion displacement mapping relationship.

[0088] S020. Calculate the coefficient vector in the mapping relationship formula of temperature-thermal expansion displacement corresponding to each of the temperature sensors.

[0089] The following will be specifically explained in the form of embodiments.

[0090] An embodiment two of the thermal expansion dynamic compensation method of the high-temperature 3D printer disclosed in the present application, the step S010 specifically includes the following sub-steps:

[0091] S011. Obtain the temperature values of N sensors at a certain moment; at the same time, use a high-temperature resistant distance sensor to measure the measurement distance between the nozzle and the printing platform.

[0092] S012. Calculate the thermal expansion displacement ΔZ based on the measurement distance and the initial distance.

[0093] S013. Repeat the test M times to calibrate the mapping relationship dataset of temperature-thermal expansion displacement: {(t1, t2, t3... t n ), ΔZ}.

[0094] where t n is the measured temperature of the nth temperature sensor, and ΔZ is the thermal expansion displacement.

[0095] Specifically, the high-temperature resistant distance sensor used in the present application includes accurately measuring the thermal expansion displacement through a laser interferometer, or a non-contact high-temperature eddy current ranging sensor (such as KAMAN KD-1925), a laser coaxial displacement meter (Keyence CL-V020), etc. Of course, those skilled in the art can also choose other ranging devices to achieve distance measurement in the high-temperature 3D printer.

[0096] During data acquisition, the N temperature sensors and the high-temperature resistant distance sensor realize synchronous acquisition of sensor signals through a multi-channel data acquisition system to ensure the time-domain consistency of the temperature data at each position.

[0097] Preferably, to ensure data reliability, during M - time test sampling, it should be ensured that the temperature values of the sampling samples cover the test temperature threshold range, and the distribution at different temperature points is as uniform as possible (for example, between the temperature threshold range of 200°C to 350°C, a sample point is taken every 10°C), rather than concentrated in a small temperature interval. If the sample temperature distribution is non - uniform (such as random sampling or sampling only concentrated in the high - temperature or low - temperature section), it may cause the test results to not fully reflect the true performance of the object under test at different temperatures, thus affecting the credibility of the conclusion.

[0098] In an implementation manner of this embodiment, the temperature sensor in the constant - temperature chamber can be designated as the reference sensor. Based on the temperature value measured by the reference sensor, a high - temperature - resistant distance sensor is used to perform temperature - thermal expansion displacement measurement at preset temperature intervals within the specified temperature measurement range.

[0099] Specifically, monitor that the temperature fluctuation of the temperature measurement point is about ±1°C, and perform measurement after reaching a steady state. When the temperature measured by the reference temperature sensor rises to the preset temperature interval, use a high - temperature - resistant laser rangefinder to measure the real - time distance between the nozzle and the printing platform, and record the values of all temperature sensors at the same time. For example, when the temperature of the temperature measurement point at the key position of the core cavity reaches the 10°C interval point (such as rising from 200°C to 210°C), it is used as a trigger data point to start a data measurement and continue for a period of time, such as 15 - 30 min. Of course, relevant technicians can set the temperature measurement interval and measurement time by themselves. For example, to speed up the test progress, the interval temperature can be adjusted to 15°C or 20°C, etc.

[0100] This application discloses a third embodiment of the thermal expansion dynamic compensation method for a high - temperature 3D printer. On the basis of any one of the above - mentioned methods, the step S020 specifically includes the following sub - steps:

[0101] S021, establish the first - temperature - parameter matrix T of the temperature sensor:

[0102]

[0103] Establish the thermal expansion displacement matrix Y:

[0104] Y = [ΔZ1, ΔZ2, ΔZ3, … ΔZ m T ;

[0105] Where t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the measured temperature of the first temperature sensor in the first test sample; t nm is the measured temperature of the nth temperature sensor in the mth test sample.​

[0106] S022, construct the first coefficient vector equation W1 based on the first temperature parameter matrix and the mapping relationship between temperature and thermal expansion displacement:

[0107] w1 = [ω1, ω2... ω n ;

[0108] Y = (T - t0)w1;

[0109] (T - t0) T (T - t0)w1 = (T - t0) T Y;

[0110] w1 = ((T - t0) T (T - t0)) -1 (T - t0) T Y;

[0111] where T is the first temperature parameter matrix, t0 is the initial ambient temperature; Y is the thermal expansion displacement matrix;

[0112] Based on this embodiment, using the calculation method in the ideal state of this embodiment, the step S200 specifically includes:

[0113] Obtain the current real-time temperature; substitute the linear term coefficient ω corresponding to each temperature sensor i into the following first mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under the current real-time temperature condition:

[0114]

[0115] where ω i is the linear term coefficient corresponding to the i-th sensor; t i is the real-time temperature measured by the i-th temperature sensor; t0 is the initial ambient temperature; ε is the error term.

[0116] Specifically, ΔZ = ω1(t1 - t0) + ω2(t2 - t0) + ω3(t3 - t0)... + ω n (t n - t0);

[0117] where ω1 is the linear term coefficient corresponding to the first sensor; …; ω n is the linear term coefficient corresponding to the n-th sensor; t1 is the real-time temperature measured by the first temperature sensor; …; t n is the real-time temperature measured by the n-th temperature sensor.

[0118] Based on the calculation result, the compensated height value Z of the device Final= Z - axis height after thermal expansion - ΔZ.

[0119] This application discloses an embodiment 4 of the dynamic thermal expansion compensation method for a high - temperature 3D printer. Since the print head and the frame in the device are usually composed of different materials (carbon steel, titanium alloy, 6061, POM plastic, etc.), the difference in the thermal expansion coefficients of each material will lead to non - linear deformation. For example, the thermal expansion coefficient of the carbon steel cross - beam, the titanium alloy TC4 of the print head heating block bracket, the aluminum alloy 6061 of the print head bracket, etc. After the superposition of relevant thermal deformations, the overall deformation displacement shows non - linear thermal gradient and non - uniformity of the thermal gradient. The local heating rate of the print head is high, while the temperature in other areas is low. Especially in the cross - beam area, it is isolated by a bellows cover, and there is an obvious temperature gradient. The non - uniform thermal field leads to the distribution of thermal stress. At high temperatures, due to creep (slow plastic deformation) and thermal hysteresis effect (the change rate of the temperature field affects the deformation response) of the material, the instantaneous thermal expansion amount deviates from the steady - state theoretical value. Based on the above theory, considering the non - linearity of thermal expansion, on the basis of Embodiment 1 or Embodiment 2 of the above - mentioned method, the step S020 specifically includes the following sub - steps:

[0120] S021, establish the second temperature parameter matrix T of the temperature sensor and the thermal expansion displacement matrix Y:

[0121]

[0122] Y = [ΔZ1, ΔZ2, ΔZ3, … ΔZ m T ;

[0123] where t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the measured temperature of the first temperature sensor in the first test sample; t nm is the measured temperature of the nth temperature sensor in the mth test sample; ΔZ m is the thermal expansion displacement measured in the mth test sample.

[0124] S022, based on the second temperature parameter matrix and the mapping relationship between temperature and thermal expansion displacement, construct the second coefficient vector equation W2:

[0125] w2 = [ω1, ω2... ω n , β1, β2... β n T ;

[0126] w2 = (T T T) -1 T T Y;

[0127] where T is the second temperature parameter matrix and Y is the thermal expansion displacement matrix.​​

[0128] S023, the linear term coefficient ω in the second mapping relationship formula corresponding to each of the temperature sensors is calculated by the least squares method i and the quadratic term coefficient β i , i ∈ 1 to n.

[0129] In an implementation manner of this embodiment, in matrix solution, if the matrix is invertible, it can be directly solved.

[0130] In another implementation manner of this embodiment, in matrix solution, if the matrix is close to a singular matrix, the method of singular value decomposition is used for calculation. Specifically, if the matrix is close to singular (the determinant is close to zero and the condition number is large), direct solution will result in unstable or inaccurate solutions due to numerical errors. The method of singular value decomposition (SVD decomposition, Singular Value Decomposition) decomposes an arbitrary matrix into the product of three special matrices. In SVD, ignoring extremely small singular values can avoid numerical instability, but it will introduce approximate solutions (such as Tikhonov regularization), sacrificing efficiency for stability, and controlling errors by analyzing singular values.

[0131] Based on this embodiment, considering the calculation method under the non - linear problem of thermal expansion, the step S200 specifically includes: obtaining the current real - time temperature; substituting the linear term coefficient ω i and the quadratic term coefficient β i corresponding to each of the temperature sensors into the following second mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under the condition of the real - time temperature:

[0132]

[0133] where ω i is the linear term coefficient corresponding to the i - th sensor; t i is the real - time temperature measured by the i - th temperature sensor; t0 is the initial ambient temperature; ε is the error term.

[0134] This embodiment online - optimizes compensation parameters by the least squares method, adapts to material and environmental changes, and directly corrects the Z - axis height based on the real - time temperature field. Based on the thermal expansion compensation method of this application, the thermal equilibrium waiting time is shortened from 2 - 4 hours to 10 - 15 minutes. There is no need to wait for the equipment to reach thermal equilibrium (from low temperature to thermal equilibrium), and printing can be started after the hot bed temperature rises (the hot bed temperature rise is to ensure the adhesion of the first - layer model). It can significantly reduce the printing failure rate, reduce material waste, and at the same time improve the dimensional accuracy of the formed parts, providing a more reliable additive manufacturing solution for high - end fields such as aerospace and medical implants.

[0135] Another embodiment of the thermal expansion dynamic compensation method for a high-temperature 3D printer is provided in this application. Based on any one of the embodiments of the above method, the following steps are further included:

[0136] Based on the trend of the temperature field model, use an artificial intelligence algorithm or a neural network model to predict the temperature value at a future moment, and compensate the Z-axis height in advance according to the predicted temperature value to offset the lag during instruction response. This further improves the reliability of Z-axis correction and ensures the accuracy of the formed parts.

[0137] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these changes and modifications.

[0138] Based on the same concept, this application also discloses a thermal expansion dynamic compensation system for a high-temperature 3D printer. The system is used to implement the steps described in any one of the above method embodiments. Specifically, an embodiment of a thermal expansion dynamic compensation system for a high-temperature 3D printer in this application specifically includes: a memory, a processor, and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the thermal expansion dynamic compensation method for a high-temperature 3D printer described in any one of the above embodiments.

[0139] Based on the above embodiments, another embodiment of a thermal expansion dynamic compensation system for a high-temperature 3D printer is disclosed in this application. Referring to the attached Figure 4 description, it specifically includes the following sub-modules:

[0140] A temperature acquisition module, which is used to measure the real-time temperature of each thermal expansion sensitive area through N temperature sensors arranged on the 3D printer.

[0141] An algorithm module, which is used to substitute the pre-calculated coefficient vector into the mapping relation formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition. Among them, the coefficient vector is obtained by calibrating the temperature-thermal expansion displacement mapping relation offline and fitting it by the least squares method.

[0142] A compensation module, which is used to compensate the real-time distance between the nozzle and the printing platform based on the thermal expansion displacement so that the compensated distance is consistent with the initial distance.

[0143] A relationship determination module, which is used to use a high-temperature resistant distance sensor to pre-determine the data set of the temperature-thermal expansion displacement mapping relation.

[0144] The algorithm module is further configured to calculate the coefficient vector in the mapping relation formula of temperature-thermal expansion displacement corresponding to each temperature sensor.

[0145] Based on the same concept, the present application also discloses a high-temperature 3D printer. Temperature sensors are respectively arranged at N thermal expansion sensitive areas on the high-temperature 3D printer. It is further equipped with a thermal expansion dynamic compensation system for a high-temperature 3D printer as described in the above embodiment.

[0146] A thermal expansion dynamic compensation method, system and a high-temperature 3D printer of the present application have the same technical concept, and the technical details of the embodiments of the three can be mutually applicable. To avoid repetition, they will not be elaborated here.

[0147] Those skilled in the art can clearly understand that for the convenience and brevity of description, only the above division of each program module is used as an example. In practical applications, the above functions can be assigned to different program modules according to needs, that is, the internal structure of the device can be divided into different program units or modules to complete all or part of the functions described above. Each program module in the embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in a processing unit. The above integrated units can be implemented in the form of hardware or in the form of software program units. In addition, the specific names of each program module are only for the convenience of mutual distinction and do not limit the protection scope of the present application.

[0148] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

Claims

1. A method for dynamic compensation of thermal expansion of a high-temperature 3D printer, characterized in that: The steps include: The real-time temperature of each thermal expansion sensitive area is measured by N temperature sensors arranged on the 3D printer; Substituting the pre-calculated coefficient vector into the mapping relationship formula, the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition is calculated; wherein the coefficient vector is obtained by offline calibration of the mapping relationship between temperature and thermal expansion displacement and fitting by the least square method; Based on the thermal expansion displacement, the real-time distance between the nozzle and the printing platform is compensated so that the compensated distance is consistent with the initial distance.

2. A high temperature resistant distance sensor, within a specified temperature measurement range, according to claim 1, a method for dynamic compensation of thermal expansion of a high temperature 3D printer, characterized in that: Also includes: Using a high temperature resistant distance sensor, a data set of the mapping relationship between temperature and thermal expansion displacement is measured in advance; In order to calculate the coefficient vector in the mapping relationship formula of temperature-thermal expansion displacement corresponding to each temperature sensor.

3. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 2, characterized in that: The method of using a high temperature resistant distance sensor to pre-measure a data set of a mapping relationship between temperature and thermal expansion displacement specifically includes: Obtaining the temperature values ​​of N sensors at a certain moment; and simultaneously using a high temperature resistant distance sensor to measure the distance between the nozzle and the printing platform; Calculating a thermal expansion displacement ΔZ based on the measured distance and the initial distance; Repeat the test M times to calibrate the temperature-thermal expansion displacement mapping relationship data set: {(t1, t2, t3...t n ),ΔZ}; Among them, t n is the measured temperature of the nth temperature sensor, and ΔZ is the thermal expansion displacement.

4. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 3, characterized in that: Also includes: designating the temperature sensor in the constant temperature chamber as a reference sensor; Based on the temperature value measured by the reference sensor, the temperature-thermal expansion displacement is measured at every preset temperature interval.

5. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 3 or 4, characterized in that: The calculation to obtain the coefficient vector in the temperature-thermal expansion displacement mapping relationship formula corresponding to each temperature sensor specifically includes: Establishing a first temperature parameter matrix T and a thermal expansion displacement matrix Y of the temperature sensor; Y=[ΔZ1,ΔZ2,ΔZ3,…ΔZ m ] T ; Where t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the temperature measured by the first temperature sensor in the first test sample; t nm is the measured temperature of the nth temperature sensor in the mth test sample; ΔZ m is the thermal expansion displacement measured in the mth test sample; Based on the mapping relationship between the first temperature parameter matrix and the temperature-thermal expansion displacement, the first coefficient vector equation W1 is constructed: w1=[ω1,ω2...ω n ]; w1=((T-t0) T (T-t0)) -1 (T-t0) T Y; Where T is the first temperature parameter matrix, t0 is the initial ambient temperature; Y is the thermal expansion displacement matrix; The linear term coefficient ω in the first mapping relationship formula corresponding to each temperature sensor is obtained by least squares method. i , i∈1~n.

6. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 5, characterized in that: Substituting the pre-calculated coefficient vector into the mapping relationship formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition specifically includes: Get the current real-time temperature; The linear term coefficient ω corresponding to each temperature sensor i Substitute the following first mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under real-time temperature conditions: Among them, ω i is the linear term coefficient corresponding to the i-th sensor; i is the real-time temperature measured by the i-th temperature sensor; t0 is the initial ambient temperature; ε is the error term.

7. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 3, characterized in that: The calculation to obtain the coefficient vector in the temperature-thermal expansion displacement mapping relationship formula corresponding to each temperature sensor specifically includes: Considering the nonlinearity of thermal expansion, a second temperature parameter matrix T of the temperature sensor and a thermal expansion displacement matrix Y are established; Y=[ΔZ1,ΔZ2,ΔZ3,…ΔZ m ] T ; Where t0 is the initial ambient temperature; n is the sensor number; m is the sample number; similarly, t 11 is the temperature measured by the first temperature sensor in the first test sample; t nm is the measured temperature of the nth temperature sensor in the mth test sample; ΔZ m is the thermal expansion displacement measured in the mth test sample; Based on the second temperature parameter matrix and the mapping relationship between temperature and thermal expansion displacement, the second coefficient vector equation W2 is constructed: w2=[ω1,ω2...ω n ,β1,β2...β n ] T ; w2=(T T T) -1 T T Y; Wherein, T is the second temperature parameter matrix, and Y is the thermal expansion displacement matrix; The linear term coefficient ω in the second mapping relationship formula corresponding to each temperature sensor is obtained by least squares method. i and the quadratic coefficient β i , i∈1~n.

8. A method for dynamic compensation of thermal expansion of a high temperature 3D printer as claimed in claim 7, characterized in that: Substituting the pre-calculated coefficient vector into the mapping relationship formula to calculate the thermal expansion displacement between the nozzle and the printing platform under the current temperature condition; Specifically include: Get the current real-time temperature; The linear term coefficient ω corresponding to each temperature sensor i and the quadratic term coefficient β i Substitute the following second mapping relationship formula to calculate the thermal expansion displacement ΔZ between the nozzle and the printing platform under real-time temperature conditions: Among them, ω i is the linear term coefficient corresponding to the i-th sensor; i is the real-time temperature measured by the i-th temperature sensor; t0 is the initial ambient temperature; ε is the error term.

9. A thermal expansion dynamic compensation system for a high temperature 3D printer, comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 8.

10. A high temperature 3D printer, characterized in that: Temperature sensors are respectively arranged at the N thermal expansion sensitive areas on the high-temperature 3D printer; and the high-temperature 3D printer is also equipped with a thermal expansion dynamic compensation system according to claim 9.

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