Injection molding and post-treatment integrated process for resin teeth

Abstract

The invention discloses a resin tooth injection molding and post-treatment integrated process, and relates to the technical field of dental medical instrument manufacturing. Which comprises oral cavity scanning, mold replacement, resin mixing, demolding, cleaning and sterilization, and is characterized by comprising the following steps: mold manufacturing: manufacturing a resin tooth mold according to prosthesis three-dimensional data obtained by oral cavity scanning; and injection molding: based on the first AI algorithm model, injecting the mixed resin into the mold cavity to obtain a resin tooth semi-finished product. The ultrasonic flow meters are embedded into the cooling runners in the prepared mold, the states of the cooling runners are monitored in real time, and the problems of product quality defects, production rate reduction and the like caused by blockage of the cooling runners are reduced. Meanwhile, a mold is generated through oral cavity scanning data, and personalized adaptation is achieved; through the first AI algorithm model, runner simulation is carried out in advance, so that temperature / pressure compensation is carried out in time, and the injection molding quality and efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dental medical device manufacturing, in particular to an integrated process of resin tooth injection molding and post-processing. Background Art

[0002] With the rapid development of oral restoration technology, resin teeth, as an important restorative material, have a manufacturing process whose precision and efficiency directly impact clinical outcomes. Traditional resin tooth production suffers from large process connection errors and extensive manual intervention in injection molding, demolding, and finishing. This invention achieves technological upgrades in resin tooth injection molding and post-processing through the deep integration of mechatronics and artificial intelligence.

[0003] In the denture processing scenario, a fully automatic integrated injection molding equipment with patent application number 2020230426470 discloses a fully automatic integrated injection molding method, which realizes partial process integration through the collaborative design of the mold device and the pushing device. When the mounting head is injection molded, the fixing block and the mounting head are directly integrated by injection molding, realizing the synchronous production and assembly of the fixing block and the mounting head.

[0004] However, in the production scenario of oral medical-grade resin teeth, the above-mentioned equipment still relies on a step-by-step process design, and has the following three disadvantages: (1) Its mold device adopts a fixed structure design and cannot be dynamically adjusted according to the patient's oral scan data; (2) It relies on a machine push device to complete the process integration, which is easily affected by material batches and temperature fluctuations, resulting in unstable quality; (3) Subsequent processing still requires manual intervention, and the accuracy is limited by the operator's experience. Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated process for resin tooth injection molding and post-processing to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an integrated process for resin tooth injection molding and post-processing, including oral scanning, mold replacement, resin mixing, demolding, cleaning and sterilization, characterized in that:

[0007] Mold making: Make resin tooth molds based on the three-dimensional data of the restoration obtained by oral scanning;

[0008] Injection molding: Based on the first AI algorithm model, the mixed resin is injected into the mold cavity to obtain the semi-finished resin tooth;

[0009] Curing: Based on the second AI algorithm model, the resin tooth semi-finished product is cured to obtain a cured resin tooth semi-finished product;

[0010] Laser trimming: Based on AI visual recognition method, the parts that need trimming are identified, and laser trimming is performed to obtain smooth resin tooth semi-finished products.

[0011] Furthermore, the mold manufacturing includes embedding ultrasonic flow meters in each cooling channel in the prepared mold to monitor the status of the cooling channel.

[0012] Furthermore, the ultrasonic flowmeter uses a cooling channel blockage determination method, which includes: a sudden drop in single channel flow to 70%-80% of the set threshold triggers an alarm; a difference in multi-channel flow exceeds 30%-40% of the maximum flow, triggers an alarm.

[0013] Furthermore, the injection molding, through the first AI algorithm model, includes:

[0014] S1: Data acquisition: Acquire restoration 3D data, mixed resin property data, and initial injection molding process parameters;

[0015] S2: Runner simulation: Build a 3D model of the restoration, perform meshing, simulate injection molding based on the initial injection molding process parameters and mixed resin property data, and obtain a filling time cloud map;

[0016] S3: Temperature / pressure compensation; the mold cavity is divided into thin-walled and thick-walled areas, and the injection pressure, temperature, and speed are adjusted based on the mixed resin characteristics and the cavity area position and fill time cloud map.

[0017] Furthermore, the solidification, through the second AI algorithm model, includes:

[0018] M1: Data acquisition: Acquire curing equipment data, mixed resin characteristic data and initial curing process parameters;

[0019] M2: Light curing: By calculating the light penetration depth, predicting the light curing depth, and then adjusting the light intensity, lighting time and light path to perform light curing;

[0020] M3: Thermal curing: predict the trend of curing degree with temperature and adjust the thermal curing temperature, time and location;

[0021] M4: Curing degree inspection: According to the curing equipment data, obtain the degree of curing and uncured position;

[0022] M5: Feedback control: According to the curing degree inspection results, adjust the light curing parameters and heat curing parameters and supplement the curing.

[0023] Furthermore, the laser trimming, through the AI ​​visual recognition method, includes:

[0024] N1: Model design: Design the restoration based on the 3D data of the restoration to obtain the design model;

[0025] N2: Image acquisition: Obtain the three-dimensional point cloud data of the resin tooth after demolding by scanning;

[0026] N3: 2D object detection: locate the semi-finished resin tooth area after demolding and mark key features;

[0027] N4: 3D modeling: Generate a 3D point cloud of the semi-finished resin tooth after demoulding based on N2-N3 for design model comparison;

[0028] N5: Compare to the design model: Align the 3D point cloud with the design model, calculate the deviation through the iterative closest point algorithm, and output the position information and thickness of the area that needs to be trimmed;

[0029] N6: Laser trimming: The laser trims according to the output position information and thickness of the area to be trimmed.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The integrated process of resin tooth injection molding and post-processing embeds ultrasonic flow meters in each cooling channel in the prepared mold to monitor the cooling channel status in real time, reducing problems such as product quality defects and reduced productivity caused by cooling channel blockage.

[0032] At the same time, molds are generated through oral scanning data to achieve personalized adaptation; the first AI algorithm model is used to simulate the flow channel in advance, so that temperature / pressure compensation can be performed in time to improve the quality and efficiency of injection molding; the curing is intelligently controlled through the collaboration of photothermal curing and the second AI algorithm model to achieve precise curing and reduce curing time; laser trimming is performed through AI visual recognition methods to solve the problems of poor adaptability and insufficient trimming accuracy of curved restorations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall process flow of the present invention;

[0034] Figure 2 Schematic diagram of the injection molding steps of the present invention;

[0035] Figure 3 Schematic diagram of the curing step of the present invention;

[0036] Figure 4 Schematic diagram of the laser trimming steps of the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the present invention provides a technical solution: an integrated process of resin tooth injection molding and post-processing, comprising:

[0039] Step 1: Oral scanning and resin tooth design: The operator uses a handheld intraoral scanner to move the probe to scan the patient's mouth at multiple angles to obtain three-dimensional data of the restoration's dentition, gums, and occlusal relationship; then the resin tooth model is designed in CAD software to obtain the design model.

[0040] Step 2: Mold making, including:

[0041] S1: 3D modeling: Based on the 3D data of the restoration obtained by oral scanning, combined with the analysis of the resin material's fluidity, shrinkage, and cooling characteristics, CAD software is used to perform 3D modeling to determine the mold cavity size and shape;

[0042] S2: Mold Design: Determine the mold structure, including the movable mold, fixed mold, gating system, cooling system, and ejection system. When designing the cooling system, reserve a location for an ultrasonic flowmeter in the cooling channel to ensure that the flowmeter can accurately measure the coolant flow rate. When designing the gating system, select the appropriate gate location and type to ensure that the resin can evenly fill the mold cavity. When designing the ejection system, include ejectors and bevel ejectors to ensure that the resin teeth can be smoothly demolded.

[0043] S3: Material selection: Choose mold steel with high hardness and wear resistance to make the mold;

[0044] S4: Processing and Manufacturing: First, the mold material is rough-machined to remove excess material and roughly shape the mold. At the same time, internal stress of the material is eliminated through drilling. Then, CNC machine tools are used to precisely machine the mold parts. EDM and wire cutting are used for complex shapes and small parts. The installation holes for the ultrasonic flow meter are reserved in the cooling channel, and the corresponding fixing structure is machined. Finally, the mold cavity is polished to ensure the smooth surface of the resin teeth, and chemical surface treatment is performed on the parts that need to be etched.

[0045] S5: Cooling system installation: Process cooling channels in the mold to ensure that the coolant can flow evenly; embed an ultrasonic flow meter in the cooling channel and fix it with threads or buckles to ensure the sealing between the flow meter and the cooling channel;

[0046] S6: Assembly and debugging: Assemble the processed mold parts, adjust the mold gap, and ensure the closing accuracy of the mold during the injection molding process and the consistency of the product size; after assembly, install the mold on the injection molding machine for trial film, observe the molding quality of the resin teeth, including size, appearance and defects, check the reading of the ultrasonic flowmeter to ensure that it is placed in a suitable position and can accurately measure the coolant flow, and then adjust the mold parameters according to the trial mold results to obtain the finished mold.

[0047] It should be noted that the methods for determining cooling channel blockage include: a sudden drop in the flow rate of a single channel to 70%-80% of the set threshold triggers an alarm; a difference in the flow rate of multiple channels exceeds 30%-40% of the maximum flow rate, triggering an alarm. When the cooling system is operating stably, the flow rate of a single channel usually does not suddenly drop by more than 20%-30%. If the flow rate drops to 70%-80%, it indicates that there may be partial blockage, such as sediment accumulation or foreign matter stuck, but it is not yet completely blocked. At this time, the alarm can intervene in advance to avoid system overheating or pressure surges. Under normal circumstances, the flow rate of parallel channels is affected by pipeline resistance, valve opening, etc., and the difference should be less than 10%-20%. If the flow rate of a channel is 30%-40% lower than that of other channels, it indicates that the channel is obviously abnormal, such as local blockage or leakage, and an alarm needs to be triggered. This threshold avoids false alarms, such as short-term flow fluctuations, and can effectively identify faults.

[0048] Step 3: Mold replacement: Turn off the power of the injection molding machine, drain the hydraulic system and cooling water circuit, use a hydraulic ejector to push open the old mold at a speed of 5mm / s, then use a copper shovel to remove residual resin, and finally replace the new mold.

[0049] Step 4: Mix the resin: Mix the epoxy resin, accelerator cobalt isooctanoate, and curing agent potassium ethyl copper peroxide in a ratio of 100:1:2.

[0050] Note that if accelerated curing is required, N,N-dimethylaniline can be added as an accelerator. The epoxy resin, cobalt 2-ethylhexanoate, potassium ethyl copper peroxide, and N,N-dimethylaniline should be mixed in a ratio of 100:0.8:1.5:0.3. The order of adding the materials is: epoxy resin + cobalt 2-ethylhexanoate → stir evenly → N,N-dimethylaniline → stir evenly → slowly add potassium ethyl copper peroxide and stir for at least three minutes until the color is uniform, avoiding any unmixed areas.

[0051] Step 5: Injection molding: Based on the first AI algorithm model, the mixed resin is injected into the mold cavity to obtain a semi-finished resin tooth.

[0052] like Figure 2 As shown, an injection molding method is provided:

[0053] Specifically, it includes:

[0054] M1: Data acquisition: A digital model of the patient's restoration was obtained using an intraoral scanner in STL format; mixed resin characteristic data included viscosity-temperature curve, curing shrinkage of 3.5%, and thermal conductivity of 0.3 W / m·K; initial injection molding process parameters included injection temperature of 110°C, injection pressure of 120 MPa, and holding time of 10 s.

[0055] M2: Runner simulation: CAD software was used to draw a 3D model of the restoration. Moldflow software was used to divide the restoration model into a hybrid mesh consisting of a tetrahedral core and boundary layer edges, with a minimum cell size of 0.1 mm. Injection molding was simulated based on the initial injection molding process parameters and the mixed resin property data to obtain a filling time cloud map with the hysteresis area marked.

[0056] M3: Temperature / pressure compensation; the mold cavity is divided into the following: thin-walled area (thickness less than 1.5 mm), the injection speed is increased to 30 mm / s, and the mold temperature is reduced by 10°C to reduce shrinkage; thick-walled area (thickness greater than 2.5 mm), the holding pressure is increased to 1.5 times the initial pressure, and the mold temperature is increased by 5°C to promote compensation; then, based on the fill time contour, an additional 8% pressure increment is applied to the hysteresis area.

[0057] It should be noted that the injection molding process must verify the compensation effect in a closed loop, with less than three iterations to avoid over-correction. The injection molding process is carried out in a closed, 0.4 bar nitrogen environment, isolating oxygen and moisture through inert gas to prevent oxidation and deterioration of the mixed resin and improve surface quality, improve the fluidity of the mixed resin and mold filling uniformity, reduce internal stress and deformation risks, and at the same time reduce raw material consumption and scrap rate.

[0058] Step 6: Curing: Based on the second AI algorithm model, the resin tooth semi-finished product is cured to obtain a cured resin tooth semi-finished product.

[0059] like Figure 3 As shown, a curing method is provided:

[0060] Specifically, it includes:

[0061] M1: Data acquisition: Acquire curing equipment data. The wavelength of the light curing machine is 385-405nm, and the light intensity range is 50-200mW / cm 2 ,Thermosetting machine temperature control accuracy ±1℃, motion axis positioning accuracy 10μm; mixed resin characteristic data, critical exposure 15mJ / cm 2 , curing depth 0.3mm / layer, temperature-viscosity curve; initial curing process parameters, default light intensity 100mW / cm 2 , illumination time 40s / layer, thermal curing temperature 60℃, thermal curing time 60min, layer thickness setting 0.1mm;

[0062] M2: Light curing: Based on the Beer-Lambert law, combined with the resin absorption coefficient and light intensity distribution, the curing depth D is predicted. P =Exposure E0 / critical energy E C For thin-walled areas, use scanning path optimization, such as spiral filling or partitioned exposure; for thick-walled areas, increase the light intensity by 1.5 times or extend the exposure time by 10s;

[0063] M3: Thermal curing: A curing kinetics model was established using differential scanning calorimetry. The temperature gradient was adjusted to 60%-80°C, and the holding time was extended by 6 minutes for every 10°C increase. Uncured areas were heated locally with a hot air nozzle, with a temperature differential of 4°C.

[0064] M4: Cure degree inspection: Use near-infrared spectroscopy to analyze the functional group conversion rate to detect the cure degree, and use optical coherence tomography to identify internal bubbles or delamination; the acceptance threshold is a near-infrared spectroscopy conversion rate of 95% and an optical coherence tomography defect area of ​​0.5mm 2 ,When the curing degree inspection fails to meet the standard, the coordinates of the local uncured area are marked;

[0065] M5: Feedback control: Based on the results of the curing degree inspection, local defects are fixed-point supplementary curing is carried out with an accuracy of 0.1mm grid.

[0066] It should be noted that both light-curing and thermal-curing technologies require synchronous calibration to prevent resin temperature fluctuations of ±2°C from interfering with the test results. The curing process is carried out in a closed, 0.4-bar nitrogen environment, which can effectively isolate oxygen and moisture interference, significantly improving product quality and process stability. The nitrogen inert environment can prevent surface stickiness, yellowing, or strength loss caused by resin oxidation, while inhibiting micro-leakage and bubble defects caused by moisture. 0.4 bar can stabilize the reaction conditions and reduce the risk of uneven curing or deformation.

[0067] Step 7: Demolding: The mold is separated by moving the movable template backward and releasing the undercut structure of the half bevel block. The servo motor then drives the gear shaft to unscrew the thread core for thread demoulding. The vacuum suction cup then absorbs the crown at 0.5MPa to eject the part and transfer it to the robotic arm. The mold is then reset after chip removal with 0.6MPa compressed air. Finally, unqualified resin teeth are automatically sorted by an industrial camera with an accuracy of 0.01mm.

[0068] Step 8: Laser trimming: Based on AI visual recognition method, the parts that need to be trimmed are identified, and laser trimming is performed to obtain a smooth resin tooth semi-finished product.

[0069] like Figure 4 As shown, a laser trimming method is provided:

[0070] Specifically, it includes:

[0071] N1: Model design: Input the patient's oral scan data and generate a parametric model of the restoration using CAD software. The occlusal surface accuracy must be less than 50μm and the edge fitting error must be less than 30μm.

[0072] N2: Image acquisition: Use a blue light structured light scanner to obtain three-dimensional point cloud data of the resin tooth, with a point cloud density of 500 points / mm 2 ;

[0073] N3: 2D object detection: locate the crown boundary line based on the YOLOv5 model, and mark key features such as the cervical margin line and occlusal surface;

[0074] N4: 3D modeling: Use Poisson reconstruction and Laplace smoothing to pre-process the three-dimensional point cloud data of the resin tooth to generate a closed triangular mesh model with the number of facets controlled at 500,000 ± 5%;

[0075] N5: Compare the generated closed triangular mesh model with the design model: Align the generated closed triangular mesh model with the design model, iterate the ICP algorithm 50 times to converge, output the deviation heat map, and automatically mark the areas where the alignment error is greater than 80μm;

[0076] N6: Laser trimming: Use a fiber laser with a wavelength of 1064nm and a power of 20W to cut layer by layer according to the marked path planning. The cutting depth of each layer is 15μm. The real-time galvanic monitoring temperature is less than 80℃ to prevent carbonization of the resin tooth.

[0077] Step 9: Cleaning and sterilization: The smooth semi-finished resin teeth are transferred to the cleaning tank. First, 40kHz high-frequency ultrasound is used to remove microscopic debris, and then the UV-C sterilization lamp is started to activate the photocatalytic decomposition of organic residues. At the same time, 28kHz low-frequency ultrasound is used to promote the reaction. Finally, the water in the cleaning tank is drained and 60℃ hot air is passed for drying. After drying, the finished resin teeth are obtained.

[0078] In the production of medical-grade resin teeth, this process is compared with existing technologies:

[0079] Table 1 Comparison between this process and existing technology

[0080]

[0081] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is limited by the accompanying embodiments and their equivalents.

Claims

1. The integrated process of resin tooth injection molding and post-processing includes oral scanning, mold replacement, resin mixing, demoulding, cleaning and sterilization, characterized by: Mold making: Make resin tooth molds based on the three-dimensional data of the restoration obtained by oral scanning; Injection molding: Based on the first AI algorithm model, the mixed resin is injected into the mold cavity to obtain the semi-finished resin tooth; Curing: Based on the second AI algorithm model, the resin tooth semi-finished product is cured to obtain a cured resin tooth semi-finished product; Laser trimming: Based on AI visual recognition method, the parts that need trimming are identified, and laser trimming is performed to obtain smooth resin tooth semi-finished products.

2. The integrated process of resin tooth injection molding and post-processing according to claim 1, characterized in that: The mold making includes embedding ultrasonic flow meters in each cooling channel of the prepared mold to monitor the status of the cooling channel.

3. The integrated process of resin tooth injection molding and post-processing according to claim 2, characterized in that: The ultrasonic flowmeter uses a cooling channel blockage determination method, which includes: triggering an alarm when a single channel flow rate suddenly drops to 70%-80% of a set threshold; triggering an alarm when the difference in multi-channel flow rate exceeds 30%-40% of the maximum flow rate.

4. The integrated process of resin tooth injection molding and post-processing according to claim 1, characterized in that: The injection molding, through the first AI algorithm model, includes: S1: Data acquisition: Acquire restoration 3D data, mixed resin property data, and initial injection molding process parameters; S2: Runner simulation: Build a 3D model of the restoration, perform meshing, simulate injection molding based on the initial injection molding process parameters and mixed resin property data, and obtain a filling time cloud map; S3: Temperature / pressure compensation; the mold cavity is divided into thin-walled and thick-walled areas, and the injection pressure, temperature, and speed are adjusted based on the mixed resin characteristics and the cavity area position and fill time cloud map.

5. The integrated process of resin tooth injection molding and post-processing according to claim 1, characterized in that: The solidification, through the second AI algorithm model, includes: M1: Data acquisition: Acquire curing equipment data, mixed resin characteristic data and initial curing process parameters; M2: Light curing: By calculating the light penetration depth, predicting the light curing depth, and then adjusting the light intensity, lighting time and lighting path to perform light curing; M3: Thermal curing: predict the trend of curing degree with temperature and adjust the thermal curing temperature, time and location; M4: Curing degree inspection: According to the curing equipment data, obtain the degree of curing and uncured position; M5: Feedback control: According to the curing degree inspection results, adjust the light curing parameters and heat curing parameters and supplement the curing.

6. The integrated process of resin tooth injection molding and post-processing according to claim 1, characterized in that: The laser trimming, through the AI ​​visual recognition method, includes: N1: Model design: Design the resin tooth model based on the three-dimensional data of the restoration to obtain the design model; N2: Image acquisition: Obtain the three-dimensional point cloud data of the resin tooth after demolding by scanning; N3: 2D object detection: locate the semi-finished resin tooth area after demolding and mark key features; N4: 3D modeling: Generate a 3D point cloud of the semi-finished resin tooth after demoulding based on N2-N3 for design model comparison; N5: Compare to the design model: Align the 3D point cloud with the design model, calculate the deviation through the iterative closest point algorithm, and output the position information and thickness of the area that needs to be trimmed; N6: Laser trimming: The laser trims according to the output position information and thickness of the area to be trimmed.

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