Ornament wax pattern 3D printing temperature control and quantity control system and method based on data processing

Abstract

The invention relates to the field of 3D printing, in particular to an ornament wax pattern 3D printing temperature control and quantity control system and method.The ornament wax pattern 3D printing temperature control and quantity control system comprises a printing host module, a collaborative movement module, a temperature control module, a modulus forming quantity control module and a vibration analysis module, the printing host module is used for arranging a workbench and a camera, the collaborative movement module is used for conducting track compensation, and the temperature control module is used for controlling the modulus forming quantity control module; the temperature control module is used for adjusting the wax liquid preheating temperature or the wax mold printing speed, the modulus forming quantity control module is used for controlling the wax liquid extrusion thickness, and the vibration analysis module is used for eliminating nozzle vibration. The casting qualification rate of the wax mould and the design freedom degree of the wax mould are improved, the material cost is saved, the surface quality is improved, the printing risk of the wax mould is reduced, the mould forming efficiency is improved, and the 3D printing success rate and the quality of an ornament wax mould casting are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing, in particular to a jewelry wax mold 3D printing temperature and quantity control system and method based on data processing. BACKGROUND

[0002] 3D printing is a technology that stacks materials layer by layer to manufacture three-dimensional objects, which can manufacture complex model structures and shapes that are difficult to process by traditional methods. The 3D model manufactured by additive manufacturing has a layering structure, so the jewelry wax mold printed by 3D printing has higher complexity and aesthetics. In the process of manufacturing jewelry wax mold by 3D printing, photosensitive resin wax material is generally used for printing, and light curing technology is used to control the wax mold forming.

[0003] Because the viscosity of photosensitive resin wax material increases sharply when exposed to low temperature, it is difficult to uniformly coat the new material on the printed layer, causing layer loss problems. Therefore, the material consumption needs to be estimated before printing and the material needs to be preheated to a fixed temperature, and the liquid level needs to be checked regularly through the observation window during printing to ensure the printing quality of the wax mold. The existing wax mold material temperature control method is executed by a heating sensor, but the printing speed of different models is different, and the temperature is difficult to accurately control, so the model printing strength is poor.

[0004] In addition, although the control system of 3D printing can directly connect the MJP piezoelectric nozzle, the nozzle will still deviate from the position, the material will not be uniformly discharged, and other problems will occur due to mechanical collision and friction resistance nonlinearity during printing, which will cause the wax resin to overflow from the edge of the material tank, pollute the printed model, and also cause material shortage during printing, resulting in failure to complete printing. It is difficult to accurately control the nozzle. SUMMARY

[0005] The purpose of the present application is to provide a jewelry wax mold 3D printing temperature and quantity control system and method based on data processing to solve the problems raised in the background art.

[0006] In order to solve the above technical problems, the present application provides the following technical scheme: a jewelry wax mold 3D printing temperature and quantity control system based on data processing, comprising: a printing host module, a cooperative motion module, a temperature control module, a mold forming quantity control module and a vibration analysis module. The printing host module is used to set a moving workbench and a piezoelectric nozzle array outside a 3D printer, the moving workbench has a function of controlling three-dimensional movement of the nozzle array, which is used to control a printing position and a spraying direction, and prevent a wax mold from toppling, the piezoelectric nozzle array is used for wax liquid molding, a 3D jewelry wax mold model is input into a computer, a printing trajectory file containing a workbench rotation angle, nozzle movement coordinates and a wax liquid extrusion amount is generated through slicing software, a camera is installed beside the nozzle, a transformation matrix between a camera coordinate system and a workbench coordinate system is calculated, and registration is performed through a hand-eye calibration algorithm; The cooperative motion module is used to capture images of the nozzle and the workpiece on the workbench through the camera, to calculate the accurate position of the nozzle in real time through an image processing algorithm, to determine the deviation between the actual deposition position of the wax mold and the model trajectory slice, to input the actual trajectory slice of the wax mold printing and the real-time position of the nozzle into the computer, to establish a synthetic motion model of the workbench and the nozzle, to match the motion speed of the MJP piezoelectric nozzle of the printer through a cooperative motion algorithm, to set three-dimensional path points and output joint motion instructions of the nozzle and the workbench, and to adjust the rotation speed of the workbench and the motion speed of the nozzle for trajectory compensation. The temperature control module is used to establish a thermal analysis finite element model based on temperature feedback data when the nozzle extrudes the wax liquid, to perform transient thermal analysis through a FEM simulation model according to the thermal physical parameters of the wax material, to simulate the temperature distribution of the nozzle and the printed wax mold in the printing process, to predict the wax liquid cooling and solidification process, to establish a mapping model of the wax liquid strength, the printing speed and the initial temperature, and to adjust the wax liquid preheating temperature or the wax mold printing speed so that the molding strength of the printed workpiece is higher than a threshold value. The molding quantity control module is used to control the camera to shoot the wax liquid deposition layer image in the printing process, to extract ROI from the wax liquid deposition layer image, to calculate the pixel thickness of the wax liquid deposition layer through a wax mold thickness detection algorithm, to convert the pixel thickness into physical thickness, and to adopt an extrusion scheme of air pressure driving a screw valve when the physical thickness does not match the actual model extrusion thickness, to send instructions to a workbench servo driver and an MJP piezoelectric nozzle motion controller, to fine-tune the nozzle extrusion air pressure, and to control the wax liquid extrusion thickness. The vibration analysis module is used to install acceleration sensors on the workbench and the printing nozzle, to perform vibration tests in the empty and loaded states respectively, to identify the natural frequency and vibration mode in the printing process through modal analysis, to perform convolution processing on the motion trajectory according to the measured natural frequency and vibration mode, to minimize the residual vibration after the nozzle moves, and to determine the maximum safe motion parameters according to the strength-temperature mapping model of the wax liquid, to ensure that all motion instructions for the nozzle and the workbench are within the envelope of the safe motion parameters.

[0007] Further, the printing host module includes a drive control unit, a workbench motion unit and a visual registration unit. The drive control unit is used for controlled driving of the printer and the workbench by a servo motor with an absolute value encoder. The workbench movement unit is used for controlling the tilt angle and movement direction of the workbench, preventing the wax mold from toppling over, and realizing full closed-loop control. The visual registration unit is used for fixing a reference point at the center of the camera field of view and setting a reference point on the workbench, controlling the workbench to rotate by a fixed angle, making the camera continuously capture reference point images, and performing parameter registration through a hand-eye calibration algorithm.

[0008] Further, the cooperative movement module includes a trajectory planning unit and a feedback control unit. The trajectory planning unit is used for dynamically calculating the required movement speed vector of the nozzle when the workpiece moves, and matching the extrusion linear speed. The feedback control unit is used for generating movement instructions of each spatial axis of the workbench and movement rate instructions of the nozzle.

[0009] Further, the temperature control module includes a thermal analysis unit, a temperature simulation unit, and a strength adaptation unit. The thermal analysis unit is used for performing transient thermal analysis using finite element analysis software to determine the temperature field distribution of the wax mold. The temperature simulation unit is used for calibrating the temperature field distribution model according to the convective heat transfer coefficient between the nozzle and the exposed surface of the wax mold. The strength adaptation unit is used for adjusting the printing speed through temperature monitoring and simulation, so that the wax liquid reaches the set strength after solidification.

[0010] Further, the molding control module includes a thickness detection unit and an extrusion control unit. The thickness detection unit is used for adopting a wax mold thickness detection algorithm, including image greying, binarization, edge detection, and sub-pixel fitting algorithm, to measure the actual thickness of the wax liquid deposition layer in real time. The extrusion control unit is used for proportionally increasing the piezoelectric parameters of the corresponding nozzle when the thickness is small, and proportionally decreasing the piezoelectric parameters of the nozzle when the thickness is large.

[0011] Further, the vibration analysis module includes a modal analysis unit and a vibration suppression unit. The modal analysis unit is used for moving the workbench at different speeds and accelerations, recording vibration data, and formulating a speed and angle limitation envelope of the workbench. The vibration suppression unit is used for suppressing vibration caused by movement, and ensuring uniform line width of the extruded wax liquid through visual detection, and determining that the wax liquid extrusion amount remains constant when the nozzle position changes.

[0012] The jewelry wax mold 3D printing temperature and quantity control method based on data processing includes the following steps: Step S1. Set up a moving workbench, a piezoelectric nozzle array and a camera outside the 3D printer, fix a reference point at the center of the camera's field of view, register through a hand-eye calibration algorithm, input the jewelry wax mold model into the computer, and generate a printing trajectory file; Step S2. The camera captures the workbench image, determines the position of each nozzle in the array in real time, establishes a combined motion model of the workbench and the nozzle, and according to the deviation between the actual deposition position of the wax mold and the slice of the printing trajectory file, matches the horizontal and vertical movement speed of the MJP piezoelectric nozzle of the printer through a cooperative motion algorithm, and compensates the trajectory of the wax mold; Step S3. Establish a thermal analysis finite element model based on temperature feedback data, perform transient thermal analysis using a FEM simulation model according to the thermal physical parameters of the wax material, predict the wax liquid cooling and solidification process, establish a mapping model of wax liquid strength, deposition speed and initial temperature, and adjust the wax liquid preheating temperature or the wax mold printing speed to make the mold strength of the printed workpiece higher than the threshold value; Step S4. Control the camera to shoot the MJP array deposition image, and when the deposition thickness does not match the model printing result, use UV ultraviolet curing technology to fine-tune the array jet thickness; Step S5. Vibration test the workbench in empty and loaded states respectively, identify the natural frequency and mode shape, adjust the nozzle array position to suppress it during printing, and determine the maximum safe motion envelope of the workbench according to the strength-temperature mapping model of the wax liquid to limit the motion amplitude of the workbench.

[0013] Further, step S1 includes: Step S11. Set up a moving workbench and a piezoelectric nozzle array outside the 3D printer, the moving workbench has a function of controlling the three-dimensional movement of the nozzle array, which is used to control the printing position and the jet direction to prevent the wax mold from toppling over, and the controlled driving of the printer and the workbench is realized through a servo driver with an absolute value encoder, and the piezoelectric nozzle array is used for wax molding; Step S12. Install a camera beside the nozzle, fix a reference point at the center of the camera's field of view and set a reference point on the wax of the workbench, control the workbench to rotate by a fixed angle, make the camera continuously capture the reference point image, calculate the transformation matrix between the camera coordinate system and the workbench coordinate system, and perform parameter registration through a hand-eye calibration algorithm; Step S13. Input the 3D jewelry wax mold model into the computer, and generate a printing trajectory file containing the workbench rotation angle, nozzle array movement coordinates and wax solidification thickness through a slicing software.

[0014] Further, step S2 includes: Step S21. Load the printing trajectory file, generate the path planning of curved surface printing, set the three-dimensional path points and output the joint motion instructions of the nozzle array and the workbench, drive the 3D printer nozzle to execute the printing operation, and adjust the angle of the workbench for trajectory compensation when the trajectory deviates; Step S22. Input the actual trajectory slice of the wax mold printing and the nozzle array position into the computer, establish a combined motion model of the workbench and the nozzle array, dynamically calculate the required motion speed vector of the nozzle when the workpiece moves, match the wax liquid deposition thickness with the motion speed vector, and adjust the motion speed of the nozzle.

[0015] Further, step S3 includes: Step S31. When the nozzle extrudes the wax liquid, transient thermal analysis is performed using finite element analysis software according to the thermal physical parameters of the wax material to determine the temperature field distribution of the wax mold, the thermal physical parameters include: specific heat capacity, thermal conductivity, density, latent heat of phase change and viscosity-temperature curve, and a mapping model of wax liquid strength, printing speed and initial temperature is established; Step S32. According to the convective heat transfer coefficient of the nozzle and the exposed surface of the wax mold, the temperature field distribution model is calibrated, the printing speed and the irradiation time of the ultraviolet lamp are adjusted through temperature monitoring and simulation, so that the wax liquid reaches the set strength after solidification.

[0016] Further, step S4 includes: Step S41. Control the camera to shoot the wax liquid deposition layer image during the printing process, extract ROI from the wax liquid deposition layer image, calculate the deposition thickness of the wax mold through the wax mold thickness detection algorithm, and convert the pixel thickness into physical thickness, the wax mold thickness detection algorithm includes: image graying, binarization, edge detection and sub-pixel fitting algorithm; Step S42. In the case that the actual model extrusion thickness does not match, the piezoelectric parameters of the corresponding nozzle are increased in proportion when the actual thickness is small, and the piezoelectric parameters of the nozzle are decreased in proportion when the actual thickness is large.

[0017] Further, step S5 includes: Step S51. Install an acceleration sensor on the workbench and the printing nozzle, let the workbench move at different speeds and accelerations, record the vibration data, identify the natural frequency and vibration mode in the printing process through modal analysis, and perform convolution processing on the nozzle motion trajectory according to the measured natural frequency and vibration mode, so as to minimize the residual vibration after the nozzle moves; Step S52. According to the strength-temperature mapping model of the wax liquid, determine the maximum safe motion parameters, the maximum safe motion parameters are the maximum inclination angle and running speed of the workbench to avoid the case that the support force caused by the bonding strength of the wax mold is less than the gravity and centrifugal force of the wax mold structure, and the motion control instructions of the workbench are limited within the envelope line of the safe motion parameters.

[0018] Compared with the prior art, the present application has the following beneficial effects: The present application builds a cooperative motion system based on a computer workbench, and when the printer is running, the speed of the printer nozzle is matched through a cooperative motion algorithm, the workbench motion is controlled, the wax mold trajectory in the camera image is made to coincide with the model trajectory, a closed-loop control system for high-precision wax mold printing is constructed, different materials and printing sizes are compatible, the problems of non-coincidence of the wax mold trajectory, instability of the nozzle mechanical control and vibration affecting the printing precision are solved, and the 3D printing success rate and the final wax mold casting quality are improved.

[0019] The present application establishes a thermal analysis finite element model of the MJP piezoelectric nozzle based on temperature feedback data, simulates the temperature distribution on the printing nozzle and the jewelry wax mold, obtains a mapping relationship table of the wax liquid strength, temperature and cooling speed through offline FEM, keeps the mold strength higher than the threshold, avoids the influence of temperature fluctuation on the material performance, prevents high-temperature carbon deposition or wax liquid solidification from blocking the nozzle, helps to reduce the wax mold printing risk, and improves the mold forming efficiency.

[0020] The present application improves the vibration analysis of the 3D printer, determines the maximum motion speed and motion angle of the workbench, feeds back and adjusts the wax liquid extrusion air pressure based on a wax mold thickness detection algorithm, controls the nozzle discharge speed, makes the workbench motion speed and the wax mold printing speed stable within the set range, optimizes the acceleration and deceleration curve of the motion controller, suppresses the nozzle vibration, improves the wax mold casting qualification rate and the wax mold design freedom, saves material cost, and improves the surface quality. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the present application, and do not constitute a limitation on the present application. In the drawings: Figure 1 is a structure diagram of the jewelry wax mold 3D printing temperature and quantity control system based on data processing of the present application; Figure 2 is a step diagram of the jewelry wax mold 3D printing temperature and quantity control method based on data processing of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] Please refer to Figure 1The present invention provides a technical solution: a temperature and volume control system for 3D printing of jewelry wax models based on data processing, comprising: a printing host module, a cooperative motion module, a temperature control module, a molding volume control module, and a vibration analysis module; The printing host module is used to set up a movable worktable and a piezoelectric nozzle array outside the 3D printer. The movable worktable has the function of controlling the three-dimensional movement of the nozzle array to control the printing position and spray direction and prevent the wax model from tipping over. The piezoelectric nozzle array is used for wax molding. The 3D jewelry wax model is input into the computer, and the printing trajectory file containing the worktable rotation angle, nozzle movement coordinates and wax extrusion volume is generated by slicing software. A camera is installed next to the nozzle, the transformation matrix between the camera coordinate system and the worktable coordinate system is calculated, and registration is performed by hand-eye calibration algorithm. The printing host module includes: a drive control unit, a worktable motion unit, and a vision registration unit; The drive control unit is used to control the printer and workbench via a servo motor with an absolute encoder. The worktable motion unit is used to control the tilt angle and direction of movement of the worktable to prevent the wax mold from tipping over and to achieve full closed-loop control. The visual registration unit is used to fix a reference point at the center of the camera's field of view and set a reference point on the worktable, control the worktable to rotate at a fixed angle, so that the camera can continuously capture the reference point image, and perform parameter registration through a hand-eye calibration algorithm.

[0024] The cooperative motion module is used to capture images of the nozzle and workpiece on the worktable using a camera, calculate the precise position of the nozzle in real time using an image processing algorithm, determine the deviation between the actual deposition position of the wax model and the model trajectory slice, input the actual trajectory slice of the wax model printing and the real-time position of the nozzle into the computer, establish a composite motion model of the worktable and the nozzle, match the movement speed of the MJP piezoelectric nozzle of the printer using a cooperative motion algorithm, set three-dimensional path points and output joint motion commands of the nozzle and the worktable, and adjust the rotation speed of the worktable and the movement speed of the nozzle for trajectory compensation. The cooperative motion module includes: a trajectory planning unit and a feedback control unit; The trajectory planning unit is used to dynamically calculate the motion velocity vector required by the nozzle when it moves with the workpiece, and match it with the linear velocity of the extrusion. The feedback control unit is used to generate motion commands for each spatial axis of the worktable and motion rate commands for the nozzle.

[0025] The temperature control module is used to establish a thermal analysis finite element model based on temperature feedback data when the nozzle extrudes the wax liquid, perform transient thermal analysis using the FEM simulation model according to the thermal physical parameters of the wax material, simulate the temperature distribution of the nozzle and the printed wax mold during the printing process, predict the wax liquid cooling and solidification process, establish a mapping model of the wax liquid strength, printing speed and initial temperature, adjust the wax liquid preheating temperature or the wax mold printing speed, and make the mold forming strength of the printed workpiece higher than a threshold value. The temperature control module comprises a thermal analysis unit, a temperature simulation unit and a strength adaptation unit. The thermal analysis unit is used to perform transient thermal analysis using a finite element analysis software to determine the wax mold temperature field distribution. The temperature simulation unit is used to calibrate the temperature field distribution model according to the convective heat transfer coefficient of the nozzle and the exposed wax mold surface. The strength adaptation unit is used to adjust the printing speed through temperature monitoring and simulation to make the wax liquid reach a set strength after solidification.

[0026] The mold forming control module is used to control the camera to shoot the wax liquid deposition layer image during the printing process, extract ROI from the wax liquid deposition layer image, calculate the pixel thickness of the wax liquid deposition layer through a wax mold thickness detection algorithm, convert the pixel thickness into physical thickness, and when the physical thickness does not match the actual model extrusion thickness, adopt an extrusion scheme of air pressure driving a screw valve, send instructions to the workbench servo driver and MJP piezoelectric nozzle motion controller, fine-tune the nozzle extrusion air pressure, and control the wax liquid extrusion thickness. The mold forming control module comprises a thickness detection unit and an extrusion control unit. The thickness detection unit is used to adopt a wax mold thickness detection algorithm, including image greying, binarization, edge detection and sub-pixel fitting algorithm, and measure the actual thickness of the wax liquid deposition layer in real time. The extrusion control unit is used to proportionally increase the corresponding piezoelectric parameters of the nozzle when the thickness is small, and proportionally reduce the piezoelectric parameters of the nozzle when the thickness is large.

[0027] The vibration analysis module is used to install acceleration sensors on the workbench and the printing nozzle, perform vibration tests in the empty and loaded states respectively, identify the natural frequency and vibration mode in the printing process through modal analysis, perform convolution processing on the motion trajectory according to the measured natural frequency and vibration mode to minimize the residual vibration after the nozzle moves, determine the maximum safe motion parameters according to the strength-temperature mapping model of the wax liquid, and ensure that all motion instructions for the nozzle and the workbench are within the envelope line of the safe motion parameters.

[0028] The vibration analysis module comprises a modal analysis unit and a vibration suppression unit. The modal analysis unit is used to move the workbench at different speeds and accelerations, record vibration data, and formulate a speed and angle limit envelope for the workbench. The vibration suppression unit is used to suppress vibration caused by movement and ensure uniformity of the nozzle extrusion line width through visual detection, and to ensure that the wax liquid extrusion amount remains constant when the nozzle position changes.

[0029] The jewelry wax mold 3D printing temperature and quantity control method based on data processing includes the following steps: Step S1. A mobile workbench, a piezoelectric nozzle array, and a camera are set up outside the 3D printer, a reference point is fixed in the center of the camera's field of view, a hand-eye calibration algorithm is used for registration, a jewelry wax mold model is input into the computer, and a print trajectory file is generated; Step S1 includes: Step S11. A mobile workbench and a piezoelectric nozzle array are set up outside the 3D printer, the mobile workbench has a function of controlling the three-dimensional movement of the nozzle array to control the printing position and the spraying direction, prevent the wax mold from tilting, and realize controlled driving of the printer and the workbench through a servo driver with an absolute value encoder, and the piezoelectric nozzle array is used for wax molding; Step S12. A camera is installed beside the nozzle, a reference point is fixed in the center of the camera's field of view and a reference point is set on the wax of the workbench, the workbench is controlled to rotate by a fixed angle, the camera continuously captures images of the reference point, a transformation matrix between the camera coordinate system and the workbench coordinate system is calculated, and parameter registration is performed through a hand-eye calibration algorithm; Step S13. A 3D jewelry wax mold model is input into the computer, and a print trajectory file containing the workbench rotation angle, nozzle array movement coordinates, and wax solidification thickness is generated through slicing software.

[0030] Step S2. The camera captures the workbench image, determines the position of each nozzle in the array in real time, establishes a combined motion model of the workbench and the nozzle, matches the horizontal and vertical movement speed of the MJP piezoelectric nozzle of the printer through a coordinated motion algorithm according to the deviation between the actual deposition position of the wax mold and the slicing of the print trajectory file, and performs trajectory compensation on the wax mold; Step S2 includes: Step S21. Load the print trajectory file, generate path planning for curved surface printing, set three-dimensional path points and output joint motion instructions of the nozzle array and the workbench, drive the nozzle of the 3D printer to perform printing operations, and adjust the angle of the workbench for trajectory compensation when the trajectory deviates; Step S22. The actual trajectory slicing of the wax mold printing and the nozzle array position are input into the computer, a combined motion model of the workbench and the nozzle array is established, the required motion speed vector of the nozzle when the workpiece moves is dynamically calculated, the wax deposition thickness is matched with the motion speed vector, and the nozzle motion speed is adjusted.

[0031] Step S3. Establish a thermal analysis finite element model based on temperature feedback data, perform transient thermal analysis on the FEM simulation model according to the thermal physical parameters of the wax material, predict the wax liquid cooling and solidification process, establish a mapping model of wax liquid strength, deposition speed and initial temperature, and adjust the wax liquid preheating temperature or wax mold printing speed to make the mold strength of the printed workpiece higher than the threshold value; Step S3 includes: Step S31. When the nozzle extrudes the wax liquid, perform transient thermal analysis using finite element analysis software according to the thermal physical parameters of the wax material, determine the wax mold temperature field distribution, and the thermal physical parameters include: specific heat capacity, thermal conductivity, density, phase change latent heat and viscosity-temperature curve, and establish a mapping model of wax liquid strength, printing speed and initial temperature; Step S32. According to the convective heat transfer coefficient of the nozzle and the exposed wax mold surface, calibrate the temperature field distribution model, adjust the printing speed and the irradiation time of the ultraviolet lamp through temperature monitoring and simulation, so that the wax liquid reaches the set strength after solidification.

[0032] Step S4. Control the camera to shoot the MJP array deposition image, and according to the image, determine the deposition thickness. When the model printing result does not match, use UV ultraviolet curing technology to fine-tune the array jet thickness; Step S4 includes: Step S41. Control the camera to shoot the wax deposition layer image during printing, extract ROI from the wax deposition layer image, calculate the deposition thickness of the wax mold through the wax mold thickness detection algorithm, and convert the pixel thickness to physical thickness, and the wax mold thickness detection algorithm includes: image graying, binarization, edge detection and sub-pixel fitting algorithm; Step S42. When the actual model extrusion thickness does not match, increase the corresponding piezoelectric parameters of the nozzle in proportion when the actual thickness is too small, and decrease the piezoelectric parameters of the nozzle in proportion when the actual thickness is too large.

[0033] Step S5. Vibration test the workbench in empty and loaded states respectively, identify the natural frequency and vibration mode, adjust the position of the nozzle array to suppress it during printing, and determine the maximum safe motion envelope of the workbench according to the strength-temperature mapping model of the wax liquid, and limit the motion amplitude of the workbench.

[0034] Step S5 includes: Step S51. Install an acceleration sensor on the workbench and the printing nozzle, make the workbench move at different speeds and accelerations, record the vibration data, identify the natural frequency and vibration mode in the printing process through modal analysis, and perform convolution processing on the nozzle motion trajectory according to the measured natural frequency and vibration mode, so that the residual vibration after the nozzle motion is minimized; Step S52. According to the strength-temperature mapping model of the wax liquid, determine the maximum safe motion parameters, which are the maximum inclination angle and running speed of the workbench under the condition that the support force caused by the wax mold adhesion strength is less than the gravity and centrifugal force of the wax mold structure, limit the motion control instruction of the workbench within the envelope of the safe motion parameters.

[0035] Embodiment: When printing hollow cylindrical wax mold with 3D printer, preheat the wax liquid until the viscosity of the wax liquid reaches the printing standard, establish the temperature field model according to the room temperature and the wax liquid temperature, according to the wax liquid specification, get the strength of the wax liquid after 50s out of the nozzle under the current room temperature to support the upper layer of the wax mold, then control the printing time of the next layer of the wax mold to be 50s by slowing down the nozzle movement speed, and control the output amount of the wax liquid, shorten the printing time as the wax mold cools down until the printing is completed.

[0036] It should be noted that in this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0037] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for the purpose of limiting the present application, although the foregoing detailed description of the present application is made with reference to the foregoing embodiments, for those skilled in the art, it still can be modified to the technical solutions recorded in the foregoing embodiments, or equivalent replacement of part of the technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for temperature and volume control in 3D printing of jewelry wax models based on data processing, characterized in that, The method includes the following steps: Step S1. Set up a mobile worktable, piezoelectric nozzle array and camera outside the 3D printer, fix a reference point at the center of the camera's field of view, perform registration through hand-eye calibration algorithm, input the wax model of the jewelry into the computer, and generate a printing trajectory file; Step S2. The camera captures images of the worktable, determines the position of each nozzle in the array in real time, establishes a composite motion model of the worktable and nozzles, and performs trajectory compensation on the wax model by matching the horizontal and vertical movement speeds of the printer's MJP piezoelectric nozzles through a cooperative motion algorithm based on the deviation between the actual deposition position of the wax model and the slice of the printing trajectory file. Step S3. Establish a thermal analysis finite element model based on temperature feedback data. According to the thermal properties of the wax material, use the FEM simulation model to perform transient thermal analysis, predict the cooling and solidification process of the wax liquid, establish a mapping model between the wax liquid strength, deposition rate and initial temperature, and adjust the wax liquid preheating temperature or wax mold printing speed so that the molding strength of the printed workpiece is higher than the threshold. Step S4. Control the camera to capture images of the MJP array deposition, determine the deposition thickness based on the images, and if the results do not match the model printing results, use UV curing technology to fine-tune the array spraying thickness. Step S5. Perform vibration tests on the worktable under no-load and load conditions respectively, identify the natural frequency and mode shape, adjust the nozzle array position to suppress vibration during printing, and determine the maximum safe motion envelope of the worktable based on the wax intensity-temperature mapping model to limit the worktable's motion amplitude.

2. The method for temperature and volume control in 3D printing of jewelry wax models based on data processing according to claim 1, characterized in that: Step S1 includes: Step S11. Set up a movable worktable and a piezoelectric nozzle array outside the 3D printer. The movable worktable has the function of controlling the three-dimensional movement of the nozzle array to control the printing position and spray direction, prevent the wax model from tipping over, and realize the controlled drive of the printer and the worktable through a servo driver with an absolute encoder. The piezoelectric nozzle array is used for wax molding. Step S12. Install a camera next to the nozzle, fix a reference point at the center of the camera's field of view and set a reference point on the wax on the worktable, control the worktable to rotate at a fixed angle so that the camera continuously captures the reference point image, calculate the transformation matrix between the camera coordinate system and the worktable coordinate system, and perform parameter registration through a hand-eye calibration algorithm. Step S13. Input the 3D jewelry wax model into the computer and generate a printing trajectory file containing the worktable rotation angle, nozzle array movement coordinates, and wax curing thickness using slicing software.

3. The method for temperature and volume control in 3D printing of jewelry wax models based on data processing according to claim 2, characterized in that: Step S2 includes: Step S21. Load the printing trajectory file, generate the path plan for curved surface printing, set the three-dimensional path points and output the joint motion command of the nozzle array and the worktable, drive the 3D printer nozzle to perform the printing operation, and adjust the angle of the worktable to compensate for the trajectory when the trajectory deviates. Step S22. Input the actual trajectory slice of the wax model printing and the position of the nozzle array into the computer, establish a composite motion model of the worktable and the nozzle array, dynamically calculate the motion velocity vector required by the nozzle when the workpiece moves, match the wax deposition thickness with the motion velocity vector, and adjust the nozzle motion speed.

4. The method for temperature and volume control in 3D printing of jewelry wax models based on data processing according to claim 3, characterized in that: Step S3 includes: Step S31. When the wax liquid is extruded from the nozzle, a transient thermal analysis is performed using finite element analysis software based on the thermal property parameters of the wax material to determine the temperature field distribution of the wax mold. The thermal property parameters include: specific heat capacity, thermal conductivity, density, latent heat of phase change and viscosity-temperature curve. A mapping model between wax liquid strength, printing speed and initial temperature is established. Step S32. Based on the convective heat transfer coefficient of the nozzle and the exposed wax mold surface, calibrate the temperature field distribution model, and adjust the printing speed and UV lamp irradiation time through temperature monitoring and simulation so that the wax liquid reaches the set strength after solidification. Step S4 includes: Step S41. During the printing process, control the camera to capture images of the wax deposition layer, extract the ROI from the wax deposition layer image, calculate the deposition thickness of the wax mold through the wax mold thickness detection algorithm, and convert the pixel thickness into physical thickness. The wax mold thickness detection algorithm includes: image grayscale conversion, binarization, edge detection and subpixel fitting algorithm. Step S42. If the actual extrusion thickness does not match the actual model thickness, increase the corresponding nozzle piezoelectric parameters proportionally when the actual thickness is too small, and decrease the nozzle piezoelectric parameters proportionally when the actual thickness is too large.

5. The method for temperature and volume control in 3D printing of jewelry wax models based on data processing according to claim 4, characterized in that: Step S5 includes: Step S51. Install accelerometers on the worktable and print head, and let the worktable move at different speeds and accelerations to record vibration data. Identify the natural frequencies and mode shapes during the printing process through modal analysis. Based on the measured natural frequencies and mode shapes, perform convolution processing on the print head motion trajectory to minimize the residual vibration after the print head moves. Step S52. Based on the strength-temperature mapping model of the wax liquid, determine the maximum safe motion parameters. The maximum safe motion parameters are the maximum tilt angle and running speed of the worktable when the supporting force caused by the adhesion strength of the wax mold is less than the gravity and centrifugal force of the wax mold structure. The motion control commands of the worktable are restricted within the envelope of the safe motion parameters.

6. A temperature and volume control system for 3D printing of jewelry wax models based on data processing, characterized in that, The system includes the following modules: a printing host module, a coordinated motion module, a temperature control module, a molding quantity control module, and a vibration analysis module; The printing host module is used to set up a movable worktable and a piezoelectric nozzle array outside the 3D printer. The movable worktable has the function of controlling the three-dimensional movement of the nozzle array to control the printing position and spray direction and prevent the wax model from tipping over. The piezoelectric nozzle array is used for wax molding. The 3D jewelry wax model is input into the computer, and the printing trajectory file containing the worktable rotation angle, nozzle movement coordinates and wax extrusion volume is generated by slicing software. A camera is installed next to the nozzle, the transformation matrix between the camera coordinate system and the worktable coordinate system is calculated, and registration is performed by hand-eye calibration algorithm. The cooperative motion module is used to capture images of the nozzle and workpiece on the worktable using a camera, calculate the precise position of the nozzle in real time using an image processing algorithm, determine the deviation between the actual deposition position of the wax model and the model trajectory slice, input the actual trajectory slice of the wax model printing and the real-time position of the nozzle into the computer, establish a composite motion model of the worktable and the nozzle, match the movement speed of the MJP piezoelectric nozzle of the printer using a cooperative motion algorithm, set three-dimensional path points and output joint motion commands of the nozzle and the worktable, and adjust the rotation speed of the worktable and the movement speed of the nozzle for trajectory compensation. The temperature control module is used to establish a thermal analysis finite element model based on temperature feedback data when the nozzle extrudes wax liquid. According to the thermal property parameters of the wax material, the FEM simulation model is used to perform transient thermal analysis, simulate the temperature distribution of the nozzle and the printed wax mold during the printing process, predict the cooling and solidification process of the wax liquid, establish a mapping model between the wax liquid strength, printing speed and initial temperature, and adjust the wax liquid preheating temperature or the wax mold printing speed so that the molding strength of the printed workpiece is higher than the threshold. The molding control module is used to control the camera to capture images of the wax deposition layer during the printing process, extract the ROI from the wax deposition layer image, calculate the pixel thickness of the wax deposition layer through the wax mold thickness detection algorithm, convert the pixel thickness into physical thickness, and when it does not match the actual model extrusion thickness, a pneumatic drive combined with a screw valve extrusion scheme is adopted to send instructions to the worktable servo driver and MJP piezoelectric nozzle motion controller to fine-tune the nozzle extrusion air pressure and control the wax extrusion thickness. The vibration analysis module is used to install accelerometers on the worktable and printhead to conduct vibration tests under no-load and load conditions. It identifies the natural frequencies and mode shapes during the printing process through modal analysis. Based on the measured natural frequencies and mode shapes, it performs convolution processing on the motion trajectory to minimize residual vibration after the printhead moves. Based on the wax intensity-temperature mapping model, it determines the maximum safe motion parameters to ensure that all motion commands for the printhead and worktable are within the envelope of the safe motion parameters.

7. The temperature and volume control system for 3D printing of jewelry wax models based on data processing according to claim 6, characterized in that: The printing host module includes: a drive control unit, a worktable motion unit, and a vision registration unit; The drive control unit is used to control the printer and workbench via a servo motor with an absolute encoder. The worktable motion unit is used to control the tilt angle and direction of movement of the worktable to prevent the wax mold from tipping over and to achieve full closed-loop control. The visual registration unit is used to fix a reference point at the center of the camera's field of view and set a reference point on the worktable, control the worktable to rotate at a fixed angle, so that the camera can continuously capture the reference point image, and perform parameter registration through a hand-eye calibration algorithm.

8. The temperature and volume control system for 3D printing of jewelry wax models based on data processing according to claim 7, characterized in that: The cooperative motion module includes: a trajectory planning unit and a feedback control unit; The trajectory planning unit is used to dynamically calculate the motion velocity vector required by the nozzle when it moves with the workpiece, and match it with the deposition thickness; The feedback control unit is used to generate motion commands for each spatial axis of the worktable and motion rate commands for the nozzle.

9. The temperature and volume control system for 3D printing of jewelry wax models based on data processing according to claim 8, characterized in that: The temperature control module includes: a thermal analysis unit, a temperature simulation unit, and an intensity adaptation unit; The thermal analysis unit is used to perform transient thermal analysis using finite element analysis software to determine the temperature field distribution of the wax model. The temperature simulation unit is used to calibrate the temperature field distribution model based on the convective heat transfer coefficients of the nozzle and the exposed wax model surface. The strength adaptation unit is used to adjust the printing speed through temperature monitoring and simulation so that the wax liquid solidifies to reach the set strength.

10. The temperature and volume control system for 3D printing of jewelry wax models based on data processing according to claim 9, characterized in that: The molding control module includes: a thickness detection unit and an extrusion control unit; The thickness detection unit is used to employ a wax mold thickness detection algorithm, including: image grayscale conversion, binarization, edge detection and sub-pixel fitting algorithm, to measure the actual thickness of the wax liquid deposition layer in real time; The extrusion control unit is used to proportionally increase the corresponding nozzle piezoelectric parameters when the thickness is too small, and proportionally decrease the nozzle piezoelectric parameters when the thickness is too large. The vibration analysis module includes: a modal analysis unit and a vibration suppression unit; The modal analysis unit is used to make the worktable move at different speeds and accelerations, record vibration data, and define the limiting envelope of the worktable speed and angle. The vibration suppression unit is used to suppress vibrations caused by motion and to ensure uniform line width of the nozzle extrusion through visual detection, ensuring that the wax extrusion volume remains constant when the nozzle position changes.

Images