Mould 3D printing manufacturing method for fusion thermal deformation real-time compensation

Abstract

The invention discloses a fusion thermal deformation real-time compensation mold 3D printing manufacturing method. The method comprises the steps that 3D printing equipment is initialized, a mold design model is loaded, and the equipment comprises a printing head, a temperature sensor and a visual sensor; establishing a thermal deformation prediction model based on the thermal physical properties of the material; temperature data and deformation data are collected in real time in the printing process; calculating the real-time compensation amount through a thermal deformation prediction model based on the collected data, wherein the real-time compensation amount comprises a path compensation amount and a parameter compensation amount; dynamically adjusting a printing path and printing parameters according to the real-time compensation amount; and the steps of collection, calculation and adjustment are repeatedly executed until printing is completed, and the compensation effect is ensured through real-time verification. Through real-time data acquisition and dynamic compensation adjustment, the problem of thermal deformation in the mold 3D printing process is effectively solved, the mold manufacturing precision is remarkably improved, the post-processing requirement is reduced, and the method is suitable for additive manufacturing of high-precision molds.

Description

Technical Field

[0001] This invention relates to the field of 3D printing manufacturing technology, and in particular to a 3D printing manufacturing method for molds that integrates real-time thermal deformation compensation. Background Technology

[0002] Molds play a crucial role in industrial production, used to mold complex parts, and their precision directly affects the quality of the final product. With the development of 3D printing technology, especially additive manufacturing technology based on the B29C64 classification, mold manufacturing is increasingly adopting 3D printing methods to achieve rapid prototyping and the molding of complex structures. 3D printed molds construct mold cavities by layer-by-layer material deposition, offering advantages such as high design freedom and short manufacturing cycles. However, during the 3D printing process, material heating and cooling can lead to thermal deformation, a major issue affecting mold precision. Thermal deformation stems from the thermal expansion and contraction of the material during printing. After the print head heats and deposits the material, uneven shrinkage occurs during the cooling phase, causing dimensional deviations and shape distortions in the mold. This deviation is particularly significant in large molds or high-precision applications, potentially leading to out-of-tolerance mold cavity dimensions and affecting the molding quality of subsequent injection molding or die casting processes.

[0003] In existing technologies, compensation methods for thermal deformation mainly include offline compensation and compensation based on prediction models. Offline compensation adjusts the printing path before printing based on historical data or simulation results, but this method cannot adapt to real-time changes during the printing process, such as fluctuations in ambient temperature or batch differences in materials, resulting in limited compensation effectiveness. Compensation based on prediction models uses finite element analysis or empirical formulas to establish a thermal deformation prediction model and pre-calculates the compensation amount before printing, but the accuracy of the model is limited by the assumptions and cannot handle dynamic factors during the printing process, such as changes in printing speed or interlayer heat accumulation.

[0004] Furthermore, some technologies employ post-processing adjustments, such as machining or heat treatment correction, but this increases manufacturing time and cost and may introduce secondary errors. Therefore, existing technologies lack the ability to monitor and compensate for thermal deformation in real time during the printing process, resulting in insufficient mold manufacturing precision and low efficiency.

[0005] Specifically, in mold 3D printing, thermal deformation manifests as interlayer misalignment, warping, and dimensional shrinkage, problems that are more pronounced when printing high-temperature materials (such as engineering plastics or metal powders). Existing compensation methods often rely on static parameters, failing to respond in real-time to changes in the printing state, and the compensation calculation is disconnected from printing execution, resulting in compensation lag. Furthermore, the integration between sensor data acquisition and printing control is insufficient, making it difficult to achieve closed-loop control.

[0006] Therefore, there is an urgent need for a 3D printing method that can integrate thermal deformation compensation in real time and dynamically adjust printing parameters during the printing process to improve the precision and efficiency of mold manufacturing. Summary of the Invention

[0007] To achieve the above objectives, this invention provides a mold 3D printing manufacturing method that integrates real-time thermal deformation compensation, comprising the following steps:

[0008] Step 1: Initialize the 3D printing equipment and load the mold design model. The 3D printing equipment includes a print head, a heating platform, a temperature sensor, and a vision sensor.

[0009] Step 2: Establish a thermal deformation prediction model, which is based on the thermophysical properties of the mold material, including the material's coefficient of thermal expansion, elastic modulus, and specific heat capacity;

[0010] Step 3: During the mold printing process, temperature data and deformation data are collected in real time. The temperature data is collected by a temperature sensor, and the deformation data is collected by a vision sensor.

[0011] Step 4: Based on the temperature and deformation data collected in Step 3, calculate the real-time compensation amount using the thermal deformation prediction model. The real-time compensation amount includes the path compensation amount of the print head movement path and the parameter compensation amount of the printing parameters.

[0012] Step 5: Based on the real-time compensation amount calculated in Step 4, dynamically adjust the print head's movement path and printing parameters to manufacture the current printing layer;

[0013] Step Six: Repeat steps three through five until the mold printing is complete. After each layer is printed, verify the actual deformation of the printed layer based on the image data collected by the vision sensor. If the residual between the actual deformation and the design model exceeds the preset threshold, re-execute the compensation calculation in step four to adjust the subsequent printed layers.

[0014] Preferably, in step two, the heat deformation prediction model is calibrated using historical printing data, which is obtained from the measurement results of multiple printing experiments. The calibration process uses the least squares method to fit the model coefficients of the heat deformation prediction model so that the average error between the predicted deformation amount of the heat deformation prediction model and the actual deformation amount obtained from multiple printing experiments is less than a preset percentage.

[0015] Preferably, in step three, the temperature sensor is arranged at the printhead nozzle and the surface of the printing platform. The temperature data acquisition frequency is synchronized with the formation of the printing layer. After each printing layer is deposited, the temperature data at the printhead nozzle and the surface of the current printing layer is acquired once.

[0016] The processing of the temperature data includes calculating the average temperature of multiple sampling points and calculating the temperature gradient between different sampling points.

[0017] Preferably, in step three, the visual sensor is a high-resolution CCD camera, and the visual sensor is mounted above the printing area;

[0018] The timing of the deformation data acquisition is aligned with the cooling phase after each layer of printing is completed;

[0019] The processing of the deformation data includes extracting the contour features of the printed layer through an edge detection algorithm, and calculating the actual deformation of the printed layer relative to the design model through the calibration conversion relationship between image pixel distance and physical size.

[0020] Preferably, in step four, the path compensation amount is calculated by a geometric transformation algorithm, which maps the actual deformation amount to the coordinate offset of the printing coordinate system. The coordinate offset includes the offset of the print head in the X, Y and Z directions.

[0021] Preferably, in step four, the parameter compensation amount includes a printing speed adjustment amount and a printing temperature adjustment amount;

[0022] The printing speed adjustment is calculated based on the deformation rate, which is the amount of deformation per unit time.

[0023] The printing temperature adjustment is calculated based on the temperature gradient.

[0024] Preferably, in step five, the adjustment of the printing path is achieved by modifying the layered slicing data, applying the path compensation amount to the movement trajectory of the print head, and generating a compensated printing path;

[0025] The printing parameters are adjusted by controlling the actuator of the print head, adjusting the printing speed and printing temperature to the values ​​calculated by the parameter compensation.

[0026] Preferably, in step five, after dynamically adjusting the printing path and printing parameters, the adjustment record is fed back to the thermal deformation prediction model for updating the thermal deformation prediction model and calculating compensation for subsequent printing layers.

[0027] Preferably, the mold material is ABS plastic, and the input parameters of the thermal deformation prediction model include the coefficient of thermal expansion, elastic modulus, and specific heat capacity of ABS plastic, which are obtained from a material database.

[0028] Preferably, in step four, the period for calculating the real-time compensation amount is consistent with the period for data acquisition in step three, ensuring that the real-time compensation amount calculation and the adjustment of the printing path and parameters for each printing layer are completed before the start of manufacturing of each printing layer.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention achieves real-time compensation by acquiring temperature and deformation data in real time and combining them with a thermal deformation prediction model. Temperature data is collected through a temperature sensor, and deformation data is acquired through a vision sensor. This real-time data acquisition scheme effectively avoids the limitations of static compensation methods in dealing with dynamic changes. The real-time compensation amount calculated by the thermal deformation prediction model can not only accurately adjust the printhead path but also dynamically adjust printing parameters, ensuring effective compensation during each layer of printing.

[0031] 2. This invention integrates real-time compensation calculation with the adjustment of printing path and printing parameters into a closed-loop control system. This seamless integration of compensation calculation and printing control allows for accurate adjustment of the path and printing parameters before each layer is printed, eliminating compensation lag and thus improving printing accuracy. This closed-loop control system ensures that printing speed, printing temperature, and printing path are dynamically adjusted based on real-time feedback during the printing process, optimizing the mold manufacturing process.

[0032] 3. This invention, through compensation calculations based on a thermal deformation prediction model, can accurately predict and correct thermal deformation during the printing process. The compensation amount is calculated based on the thermophysical properties of the material, and the coordinate offset of the printing path is adjusted through a geometric transformation algorithm, further reducing the impact of thermal deformation on mold accuracy.

[0033] 4. This invention also solves the problem of increased time and cost caused by traditional post-processing adjustments. Because thermal deformation compensation is performed in real time during printing, additional processing is avoided, thereby reducing the overall manufacturing cycle and lowering manufacturing costs. Ultimately, the improved mold precision and manufacturing efficiency make this method particularly suitable for high-precision applications, such as the molding of large molds or complex structures, solving the problems of insufficient mold precision and low efficiency in traditional 3D printing technology. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart of the steps of the method of the present invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should also be noted that, to make the embodiments more comprehensive, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0037] Please see Figure 1 This invention provides a 3D printing method for molds that integrates real-time thermal deformation compensation. First, the 3D printing equipment is initialized and a mold design model is loaded, providing the foundation for the entire printing process. The equipment includes a print head, a heating platform, a temperature sensor, and a vision sensor, enabling precise temperature monitoring and deformation data acquisition. The temperature sensor monitors the temperature changes of the material during printing, while the vision sensor acquires the mold's deformation through real-time imaging, providing data support for subsequent compensation calculations.

[0038] When establishing a thermal deformation prediction model, the thermophysical properties of the mold material, such as the coefficient of thermal expansion, elastic modulus, and specific heat capacity, are combined to accurately simulate the thermal deformation behavior of the material during the printing process. By analyzing these performance parameters, the prediction model can calculate the thermal expansion and contraction of the material during the printing process, providing a theoretical basis for subsequent real-time compensation.

[0039] During the mold printing process, real-time collected temperature and deformation data are used to calculate the compensation amount. This compensation amount consists of two parts: path compensation and parameter compensation. The path compensation amount is used to correct the movement path of the print head to ensure that the mold shape is not affected by thermal deformation; the parameter compensation amount is used to adjust printing parameters (such as temperature, speed, etc.) to optimize the printing effect and avoid deformation caused by uneven temperature.

[0040] Based on real-time calculated compensation, the printhead's movement path and printing parameters are dynamically adjusted to adapt to the changes in each printing layer. After each layer is printed, image data acquired by a vision sensor is used to verify the actual deformation. If the difference between the actual deformation and the design model exceeds a preset threshold, the compensation calculation is re-executed, and the parameters and paths of subsequent printing layers are adjusted to ensure the mold's accuracy.

[0041] By collecting temperature and deformation data in real time and dynamically adjusting the compensation amount, the accuracy problems caused by thermal deformation can be effectively addressed. Unlike traditional static compensation methods, this invention can adjust in real time according to the actual printing status, greatly improving the accuracy of the mold and printing efficiency. Furthermore, through a closed-loop control system, compensation calculation and printing control are linked in real time, avoiding compensation lag, reducing post-processing requirements, lowering manufacturing costs, and improving production efficiency.

[0042] In one possible implementation, step two involves calibrating the thermal deformation prediction model to improve the accuracy of the model's predictions. This calibration process is based on historical printing data and is accomplished through measurement results obtained from multiple printing experiments. Specifically, actual deformation data under different materials and printing conditions is collected through multiple printing experiments. This data includes the deformation of the mold during the actual printing process, including influencing factors such as thermal expansion, shrinkage, and warpage.

[0043] During calibration, the model coefficients of the thermal deformation prediction model are fitted using the least squares method. The least squares method is a mathematical approach that adjusts the model coefficients by minimizing the sum of squared errors between the predicted and actual measured deformation, making the model's predictions as close as possible to the actual deformation measured in the experiment. In this process, the adjustment of the model coefficients aims to bring the average error between the predicted deformation of the thermal deformation prediction model and the experimental data to a preset minimum value. This error is typically set to an acceptable percentage. For example, the error can be set to be less than 1%.

[0044] This method of calibration using historical printing data effectively improves the accuracy of the thermal deformation prediction model, making it more adaptable to changes during the actual printing process. This improved thermal deformation prediction model can more accurately predict potential thermal deformation during printing, providing a more reliable basis for real-time compensation. The calibrated model has higher adaptability, providing effective compensation under different printing conditions, further improving mold accuracy, reducing defects caused by thermal deformation, and ultimately enhancing the stability and quality control of the entire 3D printing manufacturing process.

[0045] In one possible implementation, step three involves the acquisition and processing of temperature data. To accurately monitor thermal changes during the printing process, temperature sensors are positioned at two key locations: the printhead nozzle and the surface of the printing platform. These locations effectively capture heat sources and temperature fluctuations that may occur during the thermal deposition process. The frequency of temperature data acquisition is synchronized with the deposition progress of the printed layers; that is, temperature data is acquired immediately after each printed layer is deposited to ensure that the temperature changes of each layer during the printing process are reflected.

[0046] In the temperature data processing, the data from multiple acquisition points are first averaged. This process, by calculating the average temperature at different acquisition points, eliminates the influence of local temperature fluctuations and provides an overall temperature trend. By acquiring temperature data from multiple points at the printhead nozzle and the print platform surface, a more comprehensive thermal distribution can be obtained. Furthermore, the calculation of temperature gradients helps analyze temperature differences between different locations, revealing potential thermal non-uniformity. This information is crucial for further compensation calculations, as thermal non-uniformity directly affects the thermal deformation behavior of the material, thus impacting the mold's accuracy.

[0047] By acquiring and processing high-frequency and high-precision temperature data, the thermal state changes during the printing process can be obtained in real time, thus providing accurate data support for subsequent thermal deformation compensation. This invention accurately captures the temperature changes of each layer during printing, ensuring the accuracy of thermal deformation compensation, thereby reducing mold deformation problems caused by temperature changes and improving the precision and quality of the final printed mold.

[0048] In one possible implementation, key features of step three include the application of a vision sensor and the acquisition and processing of deformation data. First, the vision sensor employs a high-resolution CCD camera and is mounted above the printing area. This arrangement allows for comprehensive monitoring of deformation at each layer during the printing process from above, ensuring that all possible deformation information is captured.

[0049] The timing of deformation data acquisition coincides with the cooling phase after each layer is printed. Specifically, after each layer is printed, the cooling phase begins. At this point, the deformation of the printed layer has stabilized, making deformation data acquisition more accurate and effectively avoiding the impact of instantaneous deformation caused by temperature fluctuations during the printing process.

[0050] In terms of data processing, the contour features of the printed layer are first extracted using an edge detection algorithm. Edge detection algorithms can efficiently and accurately identify contour lines in an image, especially in the transition area between the printed layer and the background. This algorithm clearly locates the shape of the printed layer, providing accurate contour data for subsequent deformation calculations. Next, using the calibration conversion relationship between image pixels and physical dimensions, pixel distances are converted into actual physical dimensions. This calibration process typically uses a pre-calibrated standard physical dimension and the ratio of the corresponding pixel value to ensure the accuracy of the deformation calculation. Finally, using this processed data, the actual deformation of the printed layer relative to the design model is calculated.

[0051] By combining a high-resolution CCD camera with a precise edge detection algorithm, the deformation of each layer can be monitored in real time and accurately, providing effective data support for subsequent thermal deformation compensation. Secondly, by aligning the timing during the cooling stage, the acquired data is ensured to be more stable and reliable, avoiding interference from instantaneous temperature changes during printing. This method significantly improves the final accuracy and quality of the printed mold, helps reduce mold defects caused by deformation, and ensures the mold's functionality and precision.

[0052] In one possible implementation, step four involves calculating the path compensation amount using a geometric transformation algorithm. The core task of this algorithm is to map the actual thermal deformation to the printing coordinate system, thereby providing compensation for printhead path adjustment. Specifically, the actual deformation amount is first determined using deformation data collected by a vision sensor; this deformation is the mold deformation caused by thermal expansion or contraction during printing. Then, the geometric transformation algorithm converts these actual deformation amounts into coordinate offsets in the coordinate system.

[0053] The geometric transformation algorithm maps the actual deformation in three-dimensional space through a series of mathematical calculations, thereby obtaining the offset of the print head in various directions. These offsets involve positional adjustments in the X, Y, and Z directions. Specifically, in the X direction, the horizontal position of the print head may shift due to the thermal expansion or contraction of the material; in the Y direction, lateral deformation may occur due to temperature changes; and in the Z direction, the height of the printed layer may also be affected by thermal deformation. Therefore, the geometric transformation algorithm can provide precise path compensation for the print head by calculating these offsets, ensuring the accuracy of each layer during the printing process.

[0054] By using a geometric transformation algorithm to accurately calculate the coordinate offset of the actual deformation, the print head path can be dynamically adjusted during printing to compensate for errors caused by thermal deformation. This not only improves the accuracy of mold printing but also enables real-time responses to changes in thermal deformation, ensuring the accuracy of each printed layer and the high quality of the final mold. This method effectively reduces errors caused by thermal deformation, avoids mold defects caused by path deviations, and enhances the stability and reliability of the overall printing process.

[0055] In one possible implementation, the parameter compensation in step four includes two important aspects: printing speed adjustment and printing temperature adjustment. Both are calculated in close relation to thermal deformation and temperature gradient, aiming to further compensate for errors caused by thermal deformation by precisely controlling the speed and temperature during the printing process, thereby ensuring the accuracy and quality of the mold.

[0056] First, the printing speed adjustment is calculated based on the deformation rate. The deformation rate refers to the actual amount of deformation that occurs in the mold per unit time, typically measured using data from vision and temperature sensors. The deformation rate reflects how quickly the material deforms due to thermal expansion or contraction during printing. Based on this rate, the printing speed needs to be adjusted accordingly. Slowing down the printing speed reduces drastic material deformation during printing, helping to mitigate uneven mold deformation caused by temperature changes; conversely, increasing the printing speed can help reduce deformation in certain situations, thus maintaining higher mold precision.

[0057] Secondly, the printing temperature adjustment is calculated based on the temperature gradient. The temperature gradient refers to the temperature difference between different locations during the printing process. A larger temperature gradient can lead to more pronounced thermal deformation of the material, thus affecting the shape and size of the mold. Therefore, by adjusting the printing temperature, the temperature gradient can be effectively controlled, reducing deformation caused by temperature differences. For example, in areas with severe thermal deformation, the printing temperature can be appropriately increased to reduce the temperature difference in the material, thereby reducing deformation; while in areas with smaller temperature changes, the temperature can be decreased to prevent excessive material expansion due to overheating.

[0058] By adjusting these two parameter compensation amounts in real time, printing conditions can be dynamically optimized throughout the printing process, thereby compensating for errors caused by thermal deformation and temperature gradients. This invention significantly improves the accuracy and stability of mold printing, reduces defects caused by improper temperature and deformation rate control, and ensures the quality of each layer, resulting in a final mold that better meets design requirements.

[0059] In one possible implementation, the print path adjustment is first achieved by modifying the layer slicing data. This process involves applying path compensation to the print head's movement trajectory to generate a compensated print path. Specifically, by analyzing thermal deformation data and path offsets calculated using geometric transformation algorithms, these compensation amounts are integrated into the slicing data of each layer. The print path of each layer is precisely adjusted based on actual deformation to ensure that the print head moves along the corrected trajectory during actual printing, thereby reducing path deviations caused by thermal deformation. In this way, the print head's movement trajectory is more consistent with the design model, ensuring the dimensional accuracy and shape precision of the mold.

[0060] Secondly, the printing parameters are adjusted by controlling the actuators of the print head. While adjusting the printing path, the printing speed and temperature need to be adjusted in real time based on the compensation amount. Specifically, the printing speed is adjusted based on the deformation rate calculation results; this may involve reducing the speed to decrease thermal deformation or increasing the speed to address certain thermal effects. Simultaneously, the printing temperature is also adjusted based on the temperature gradient calculation results. In areas with significant thermal deformation, the printing temperature can be appropriately increased to reduce the thermal stress on the material; while in areas with smaller temperature differences, the temperature can be decreased to avoid excessive expansion.

[0061] By precisely controlling the printing path and parameters, and responding in real time to changes in thermal deformation, mold defects caused by temperature and speed fluctuations are reduced. The compensated printing path and optimized printing parameters significantly improve the accuracy and stability of the printing process, ensuring that the printing quality of each layer more closely matches the design goals. This method not only improves the overall quality of the mold but also reduces production costs and time wasted due to thermal deformation, further enhancing the efficiency and precision of mold manufacturing.

[0062] In one possible implementation, further refinement of step five includes dynamically adjusting the printing path and printing parameters, and then feeding these adjustments back to the thermal deformation prediction model. The core objective of this process is to ensure, by continuously updating the thermal deformation prediction model, that more accurate compensation calculations can be performed in subsequent printed layers based on the latest deformation information.

[0063] In practice, when the printing path and printing parameters are adjusted, these changes are recorded and fed back as input data to the thermal deformation prediction model. The thermal deformation prediction model is primarily used to predict the potential thermal deformation of the material during the subsequent printing process. These predictions are based on a comprehensive calculation of previous deformation data, printing speed, temperature, and other factors to arrive at the prediction results. By using the real-time adjusted printing path and parameters as new inputs, the model can continuously correct and optimize its prediction accuracy, ensuring that the thermal deformation of each layer can be accurately predicted.

[0064] By feeding back path and parameter adjustment information from each printing process to the prediction model, the model can continuously update itself, thereby improving the accuracy of predicting thermal deformation. As the model is continuously optimized, the compensation calculations for subsequent printing layers become more precise, reducing the uncertainty caused by thermal deformation and further improving mold precision and manufacturing efficiency. Furthermore, this feedback mechanism ensures that thermal deformation compensation can be adjusted in real time according to changes in the environment and process during long printing processes, resulting in a final printed mold that better meets design requirements and reducing the need for multiple adjustments and manual intervention.

[0065] In one possible implementation, the mold material used in the 3D printing manufacturing method for molds with real-time compensation for fused thermal deformation is ABS plastic. ABS plastic, as a common engineering plastic, possesses good mechanical properties and thermal stability, and is widely used in the 3D printing field. In this method, the input parameters of the thermal deformation prediction model include the coefficient of thermal expansion, elastic modulus, and specific heat capacity of the ABS plastic, which are obtained from a material database. These physical parameters have a significant impact on the thermal deformation behavior of the material; therefore, they are essential inputs to the thermal deformation prediction model.

[0066] Specifically, the coefficient of thermal expansion describes the degree of expansion of a material when the temperature changes, helping to predict the dimensional changes of the material at different printing temperatures; the modulus of elasticity reflects the material's resistance to deformation and plays an important role in the generation of thermal stress and its impact on the mold shape; specific heat capacity refers to the amount of heat required per unit mass of material to increase its temperature, affecting the material's thermal response at different temperatures. By obtaining these parameters from a database, the thermal deformation prediction model can more accurately simulate the thermal deformation behavior of ABS plastic during actual printing.

[0067] Accurate material parameter input enables the heat deformation prediction model to more precisely predict the thermal expansion and contraction phenomena that may occur in ABS plastic during the printing process. By updating and compensating for these predictions in real time, dimensional errors caused by heat deformation can be significantly reduced, improving the printing accuracy and quality of the mold. Furthermore, adjusting the model based on the physical properties of ABS plastic helps optimize key parameters such as temperature control and speed adjustment during the printing process, thereby further improving printing efficiency and reducing production costs.

[0068] In one possible implementation, the real-time compensation calculation cycle in step four is consistent with the data acquisition cycle in step three. This is to ensure that the real-time compensation calculation for each printing layer can be completed before manufacturing begins, and the printing path and printing parameters can be adjusted.

[0069] In practice, the data acquisition cycle in step three is typically synchronized with the layer switching during the printing process. The purpose of data acquisition is to gather key information such as printing materials, temperature changes, and deformation rates to provide real-time data support for thermal deformation prediction. The acquired data is usually updated before each layer is printed to ensure that the latest deformation information is fed back into the system. Therefore, the calculation cycle for real-time compensation is also consistent with the data acquisition cycle, so that the compensation amount can be calculated in a timely manner based on the latest data before each printing layer begins, thereby adjusting the printing path and related parameters.

[0070] This invention ensures that each printing layer is optimized based on the most accurate real-time data, preventing mold size and shape deviations due to outdated data or unupdated parameters. This effectively avoids errors caused by accumulated thermal deformation, resulting in more stable printing quality and accuracy for each layer. Furthermore, ensuring real-time compensation calculations for each layer before manufacturing begins makes the entire printing process more coherent and efficient, thereby improving the precision and consistency of mold manufacturing.

[0071] Example:

[0072] This embodiment focuses on 3D printing the cavity portion of an injection mold, used to mold plastic parts that require high dimensional accuracy and good surface quality. In traditional 3D printing, ABS material undergoes significant thermal deformation during the cooling phase after heating and deposition, primarily manifested as warping and dimensional shrinkage, leading to dimensional deviations in the cavity and affecting the quality of subsequent injection molding. This embodiment utilizes a real-time thermal deformation compensation method to dynamically adjust printing parameters and paths during the printing process to counteract the effects of thermal deformation.

[0073] Detailed implementation steps:

[0074] Step 1: Initialize the 3D printing equipment and load the mold design model;

[0075] The initialization process includes two parts: equipment preparation and model preparation.

[0076] Equipment Preparation: A fused deposition modeling (FDM) 3D printer conforming to the B29C64 standard was selected. This equipment includes a print head, a heating platform, a temperature sensor, and a vision sensor. The print head features a single nozzle design with a nozzle diameter of 0.4 mm. The heating platform has temperature control functionality to maintain a stable temperature during printing. The temperature sensor consists of two K-type thermocouples: one mounted on the outer wall of the print head nozzle, 2 mm from the nozzle exit, and the other mounted at the center of the printing platform. The vision sensor uses a 5-megapixel CCD camera, mounted directly above the printing area, covering the entire printing area with an optical resolution of 0.01 mm per pixel.

[0077] Model Preparation: The mold design model is the cavity part of the injection mold, in STL file format. Layered slicing data is generated using slicing software. The layered slicing parameters are set as follows: layer thickness 0.2 mm, infill density 80%, and 3 printing contours. Initial printing parameters are set based on the properties of ABS material: printing speed 50 mm / s, printing temperature 230 degrees Celsius, and platform temperature 80 degrees Celsius. These parameters are based on recommendations provided by the material supplier.

[0078] Step 2: Establish a thermal deformation prediction model;

[0079] The thermal deformation prediction model is a mathematical model based on the thermophysical properties of materials, used to predict the deformation behavior of molds under temperature changes.

[0080] The model input parameters include the coefficient of thermal expansion, elastic modulus, and specific heat capacity of ABS plastic. These parameters are obtained from a material database and are specifically: coefficient of thermal expansion 0.00008 degrees Celsius, elastic modulus 2.2 gigapascals, and specific heat capacity 1.6 joules per gram per degree Celsius.

[0081] The thermal deformation prediction model employs linear thermal expansion theory combined with thermal stress analysis. Its basic form is that the predicted deformation is equal to the coefficient of thermal expansion multiplied by the temperature change multiplied by the characteristic length, and then multiplied by a correction factor determined by the elastic modulus and specific heat capacity. The characteristic length is taken as the length in the maximum dimension direction of the mold design model.

[0082] Model calibration utilizes historical printing data, obtaining measurement results through 10 printing experiments. Each experiment involved printing a standard test mold and measuring the actual deformation. The calibration process employs the least squares method to fit the model coefficients, specifically minimizing the squared difference between the predicted and measured deformation. After calibration, the average error between the model's predicted and measured deformation is controlled within 3%. This error threshold is set based on the mold's accuracy requirements, ensuring the reliability of the model's predictions.

[0083] Step 3: Real-time data acquisition and processing;

[0084] Data acquisition includes the simultaneous acquisition of temperature and deformation data. Temperature data acquisition is achieved through two temperature sensors. The acquisition frequency is synchronized with the printing layers; immediately after the deposition of each printing layer, the temperature values ​​at the printhead nozzle and the surface of the current printing layer are acquired. The timing of acquisition is precisely controlled within one second after the completion of the current layer's printing to avoid interlayer interference.

[0085] Temperature data processing includes calculating the average temperature and temperature gradient. The average temperature is the arithmetic mean of the temperature values ​​from two sampling points. The temperature gradient is calculated as the difference between the printhead nozzle temperature and the surface temperature of the printed layer, reflecting the non-uniformity of heat conduction.

[0086] Deformation data acquisition is achieved using a vision sensor. The vision sensor acquires images 5 seconds after each layer is printed and has cooled; the cooling time is determined based on the thermal relaxation characteristics of the ABS material. Uniform lighting is ensured during image acquisition to avoid shadow interference.

[0087] Deformation data processing includes image analysis and actual deformation calculation. Image analysis employs the Canny edge detection algorithm, which consists of four steps: Gaussian filtering, gradient calculation, non-maximum suppression, and double threshold detection, to accurately extract the contour features of the printed layer. Actual deformation calculation is achieved by comparing the extracted contour with the design model contour. First, a calibration conversion relationship between image pixel distance and physical size is established. The calibration process uses a standard mesh board to determine that each pixel corresponds to 0.01 mm. Then, the positional deviation of the contour key points is calculated, and the root mean square value of all point deviations is taken as the actual deformation.

[0088] Step 4: Real-time compensation calculation;

[0089] Real-time compensation calculations are based on the data processed in step three, generating compensation amounts through a thermal deformation prediction model. The calculation process first inputs the average temperature and actual deformation into the thermal deformation prediction model to update the predicted deformation. Then, it compares the difference between the actual and predicted deformation; compensation calculations are triggered when the difference exceeds 0.01 mm. This threshold is set based on the tolerance requirements of mold manufacturing.

[0090] The path compensation amount is calculated using a geometric transformation algorithm that employs the principle of three-dimensional coordinate transformation. Specifically, the actual deformation amount is decomposed into offset components in the X, Y, and Z directions, and then these components are mapped to the coordinate offset of the printing coordinate system through a translation transformation matrix. For example, if the actual deformation amount shows that the edge of the display layer warps upward by 0.05 mm, then the path compensation amount is set to an offset of -0.05 mm in the Z direction.

[0091] The parameter compensation amounts include print speed adjustment and print temperature adjustment. Print speed adjustment is calculated based on the deformation rate, which is the amount of deformation per unit time, obtained by the ratio of the difference in actual deformation between two consecutive layers to the time interval. If the deformation rate exceeds 0.01 mm / s, the print speed is reduced proportionally. Print temperature adjustment is calculated based on the temperature gradient. If the temperature gradient is greater than 10 degrees Celsius, the print temperature is fine-tuned proportionally to reduce thermal stress.

[0092] The compensation calculation cycle is strictly consistent with the data acquisition cycle to ensure that the calculation is completed before each layer is printed.

[0093] Step 5: Dynamically adjust the print path and parameters;

[0094] The adjustment process is carried out based on the real-time compensation amount calculated in step four;

[0095] Print path adjustment is achieved by modifying the layer slicing data. Specifically, path compensation is applied to the print head's movement trajectory to generate a compensated print path. For example, the coordinate parameters of the G-code are adjusted in the slicing software, adding a compensation offset. The adjusted path ensures the print head moves along the compensated trajectory. Printing parameter adjustment is achieved by controlling the print head's actuators. Printing speed adjustment is achieved by changing the pulse frequency of the stepper motor, and printing temperature adjustment is achieved by changing the heater power. The adjustment values ​​are strictly set according to the parameter compensation amount; for example, when the printing speed adjustment is -5 mm / s, the printing speed is reduced from 50 mm / s to 45 mm / s.

[0096] After the adjustment is completed, the adjustment record, including the amount of compensation and the execution time, will be fed back to the thermal deformation prediction model for model updates and compensation calculations for subsequent layers.

[0097] Step Six: Real-time Verification and Iterative Compensation;

[0098] After each layer is printed, steps three through five are immediately repeated. The verification process involves acquiring images using a vision sensor and calculating the residual between the actual deformation and the design model. The residual is calculated as the maximum absolute value of the deviations at all measurement points.

[0099] If the residual exceeds 0.02 mm, the compensation calculation in step four is repeated to adjust the parameters of subsequent printed layers. This threshold is set based on the final usage requirements of the mold to ensure dimensional accuracy.

[0100] The iterative process continues until the mold printing is complete. Throughout the printing process, the compensation system monitors and adjusts in real time, forming an adaptive control loop.

[0101] To demonstrate the effectiveness of this embodiment, two comparative experiments were conducted. Comparative Example 1 employed a traditional offline compensation method, where the compensation amount was pre-set based on experience before printing and not adjusted during the printing process. Comparative Example 2 employed offline compensation based on a prediction model, where a fixed compensation amount was calculated using a thermal deformation prediction model, but without real-time data acquisition and adjustment. This embodiment employs the aforementioned complete real-time compensation method.

[0102] The experimental subjects were the same injection mold cavity, all made of ABS plastic. Evaluation metrics included dimensional error and printing time. Dimensional error was measured by the deviation of key mold features, and printing time was recorded as the total time from start to finish. The experimental results are shown in the table below:

[0103]

[0104]

[0105] As can be seen from the table, this embodiment is significantly superior to the two comparative examples in terms of dimensional accuracy. Although the printing time is slightly increased, the accuracy improvement is significant, meeting the requirements of high-precision mold manufacturing. This indicates that the real-time compensation method of the present invention effectively solves the problem of thermal deformation.

[0106] It is understood that in this embodiment:

[0107] Thermal deformation prediction model: This model is a combination of linear model and empirical correction. It takes into account both theoretical thermal expansion and historical data calibration to improve its practical applicability.

[0108] Edge detection algorithm: The Canny algorithm distinguishes between strong and weak edges through dual threshold detection, ensuring the accuracy of contour extraction.

[0109] Geometric transformation algorithm: Homogeneous coordinate transformation is used to convert the deformation into translation and rotation adjustments of the printing coordinate system.

[0110] Deformation rate: The deformation change of continuous layers is calculated by differential calculation to reflect the deformation trend and is used for forward compensation.

[0111] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for 3D printing molds that integrates real-time thermal deformation compensation, characterized in that, Includes the following steps: Step 1: Initialize the 3D printing equipment and load the mold design model. The 3D printing equipment includes a print head, a heating platform, a temperature sensor, and a vision sensor. Step 2: Establish a thermal deformation prediction model, which is based on the thermophysical properties of the mold material, including the material's coefficient of thermal expansion, elastic modulus, and specific heat capacity; Step 3: During the mold printing process, temperature data and deformation data are collected in real time. The temperature data is collected by a temperature sensor, and the deformation data is collected by a vision sensor. Step 4: Based on the temperature and deformation data collected in Step 3, calculate the real-time compensation amount using the thermal deformation prediction model. The real-time compensation amount includes the path compensation amount of the print head movement path and the parameter compensation amount of the printing parameters. Step 5: Based on the real-time compensation amount calculated in Step 4, dynamically adjust the print head's movement path and printing parameters to manufacture the current printing layer; Step Six: Repeat steps three through five until the mold printing is complete. After each layer is printed, verify the actual deformation of the printed layer based on the image data collected by the vision sensor. If the residual between the actual deformation and the design model exceeds the preset threshold, re-execute the compensation calculation in step four to adjust the subsequent printed layers.

2. The mold 3D printing manufacturing method with real-time thermal deformation compensation according to claim 1, characterized in that, In step two, the heat deformation prediction model is calibrated using historical printing data, which is obtained from the measurement results of multiple printing experiments. The calibration process uses the least squares method to fit the model coefficients of the heat deformation prediction model so that the average error between the predicted deformation amount of the heat deformation prediction model and the actual deformation amount obtained from multiple printing experiments is less than a preset percentage.

3. The mold 3D printing manufacturing method with real-time thermal deformation compensation according to claim 1, characterized in that, In step three, the temperature sensor is arranged at the printhead nozzle and the surface of the printing platform. The temperature data acquisition frequency is synchronized with the printing layer. After each printing layer is deposited, the temperature data at the printhead nozzle and the surface of the current printing layer is acquired once. The processing of the temperature data includes calculating the average temperature of multiple sampling points and calculating the temperature gradient between different sampling points.

4. The mold 3D printing manufacturing method with real-time thermal deformation compensation according to claim 1, characterized in that, In step three, the visual sensor is a high-resolution CCD camera, and the visual sensor is mounted above the printing area; The timing of the deformation data acquisition is aligned with the cooling phase after each layer of printing is completed; The processing of the deformation data includes extracting the contour features of the printed layer through an edge detection algorithm, and calculating the actual deformation of the printed layer relative to the design model through the calibration conversion relationship between image pixel distance and physical size.

5. The 3D printing manufacturing method for molds with real-time thermal deformation compensation according to claim 1, characterized in that, In step four, the path compensation amount is calculated by a geometric transformation algorithm, which maps the actual deformation amount to the coordinate offset of the printing coordinate system. The coordinate offset includes the offset of the print head in the X, Y and Z directions.

6. The mold 3D printing manufacturing method with real-time thermal deformation compensation according to claim 1, characterized in that, In step four, the parameter compensation amount includes the printing speed adjustment amount and the printing temperature adjustment amount; The printing speed adjustment is calculated based on the deformation rate, which is the amount of deformation per unit time. The printing temperature adjustment is calculated based on the temperature gradient.

7. The 3D printing manufacturing method for molds with real-time thermal deformation compensation according to claim 1, characterized in that, In step five, the adjustment of the printing path is achieved by modifying the layered slicing data, applying the path compensation amount to the movement trajectory of the print head, and generating a compensated printing path; The printing parameters are adjusted by controlling the actuator of the print head, adjusting the printing speed and printing temperature to the values ​​calculated by the parameter compensation.

8. The 3D printing manufacturing method for molds with real-time thermal deformation compensation according to claim 1, characterized in that, In step five, after dynamically adjusting the printing path and printing parameters, the adjustment records are fed back to the thermal deformation prediction model for updating the thermal deformation prediction model and calculating compensation for subsequent printing layers.

9. The 3D printing manufacturing method for molds with real-time thermal deformation compensation according to claim 1, characterized in that, The mold material is ABS plastic, and the input parameters of the thermal deformation prediction model include the coefficient of thermal expansion, elastic modulus and specific heat capacity of ABS plastic, which are obtained from a material database.

10. A method for 3D printing a mold with real-time compensation for thermal deformation according to claim 6, characterized in that, In step four, the calculation cycle for the real-time compensation amount is kept consistent with the data acquisition cycle in step three, ensuring that the calculation of the real-time compensation amount and the adjustment of the printing path and parameters for each printing layer are completed before the start of manufacturing of each printing layer.

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