An apparatus and method for surface treatment of additive manufacturing parts using chemical vapor

Abstract

This invention relates to the field of plastic molding technology, specifically to an apparatus and method for surface treatment of additively manufactured parts using chemical vapor. The method includes: determining the theoretical feed rate for the pre-charging and stabilizing stage, feeding the material, determining the effective volume of the polishing chamber to determine the theoretical feed rate for the gradient pressurization stage, feeding the material, obtaining the actual gas pressure at the end of the gradient pressurization stage, determining the vaporization efficiency deviation coefficient for the gradient pressurization stage to determine the target feed rate correction value for the precise pressurization stage, and combining this with the initial feed rate control at each moment in the precise pressurization stage to determine the final feed rate control for each control cycle in the precise pressurization stage, until entering the heat preservation and pressure holding stage, where the surface polishing of the plastic part to be polished is completed under heat preservation and pressure holding conditions. This invention achieves high-precision and high-consistency control of the chemical vapor concentration, improving the surface polishing effect of plastic parts.

Description

Technical Field

[0001] This invention relates to the field of plastic molding technology, and more specifically to an apparatus and method for surface treatment of additive manufacturing parts using chemical vapor. Background Technology

[0002] For polishing the surface of plastic parts, existing chemical reagent immersion methods typically involve placing the parts in a basket and then immersing them in a chemical reagent that dissolves the material. After a period of time, the reagent penetrates the parts and corrodes and levels the micropores on their surface. After a reaction period, the parts are removed from the reagent and dried, resulting in a smooth surface. In contrast, existing chemical vapor polishing technology generally employs a material quality control method. Its core principle is based on the ideal gas law. The total mass of organic solvent required is calculated according to the nominal volume of the polishing chamber and the target vapor concentration. Concentration control within the chamber is achieved through quantitative addition of the solvent in a single batch or in multiple batches. This method features simple equipment structure and convenient operation.

[0003] Existing problems: In additive manufacturing parts processing scenarios, existing chemical vapor polishing technology cannot quantify the loss of fixed materials caused by surface adsorption, system pipeline and inner wall condensation, and cannot compensate for the impact of ambient temperature fluctuations on the vaporization efficiency of organic solvents in real time. This results in a large deviation between the actual vapor concentration in the chamber and the theoretical calculation value. Furthermore, the lack of a closed-loop feedback control mechanism can easily lead to defects such as over-etching, flow marks or internal blind holes and insufficient channel treatment on the parts surface. It is also difficult to effectively guarantee the consistency of the processing effect of different batches. Summary of the Invention

[0004] This invention provides an apparatus and method for surface treatment of additive manufacturing parts using chemical vapor, in order to solve existing problems.

[0005] The present invention provides an additive manufacturing part surface treatment apparatus and method utilizing chemical vapor, which adopts the following technical solution:

[0006] One embodiment of the present invention provides a surface treatment method for additively manufactured parts using chemical vapor, the method comprising the following steps:

[0007] Obtain the nominal volume of the polishing chamber, the volume of the plastic part to be polished, the target air pressure corresponding to the plastic part to be polished, and the molar mass of the organic solvent;

[0008] Based on the difference between the nominal volume of the polishing chamber and the volume of the plastic part to be polished, combined with the target air pressure of the plastic part to be polished and the molar mass of the organic solvent, the theoretical feed rate for the pre-charging and stabilizing stage is determined; the material is fed according to the theoretical feed rate for the pre-charging and stabilizing stage to determine the effective volume of the polishing chamber.

[0009] Based on the effective volume of the polishing chamber, determine the theoretical feed rate for the gradient pressurization stage; based on the theoretical feed rate for the gradient pressurization stage, determine the theoretical feed rate for the gradient pressurization stage; feed according to the theoretical feed rate for the gradient pressurization stage, and obtain the actual gas pressure at the end of the gradient pressurization stage; based on the actual gas pressure at the end of the gradient pressurization stage, determine the gasification efficiency deviation coefficient for the gradient pressurization stage.

[0010] Based on the magnitude of the gasification efficiency deviation coefficient during the gradient pressurization stage, the target feed rate correction value for the precision pressurization stage is determined. The initial feed rate control value at each moment during the precision pressurization stage is obtained. Combined with the target feed rate correction value for the precision pressurization stage, the initial feed rate control value is limited to determine the final feed rate control value corresponding to each control cycle during the precision pressurization stage, until the heat preservation and pressure preservation stage is entered. Under the heat preservation and pressure preservation conditions, the surface polishing treatment of the plastic parts to be polished is completed.

[0011] Furthermore, the specific steps for determining the theoretical feed rate during the pre-charging and stabilization stage are as follows:

[0012] The difference between the nominal volume of the polishing chamber and the volume of the plastic part to be polished is recorded as the material gas filling volume.

[0013] Based on the ideal gas law, the target total theoretical feed rate is determined by the target gas pressure corresponding to the plastic part to be polished, the gas filling volume of the material, the molar mass of the organic solvent, the ideal gas constant, and the preset process preheating reference temperature.

[0014] The product of the target total theoretical feed rate and the preset first adjustment coefficient is denoted as the theoretical feed rate during the pre-charging and stabilization stage.

[0015] Furthermore, the specific steps for determining the effective volume of the polishing chamber are as follows:

[0016] Feed materials according to the theoretical feed rate during the pre-charging and stabilizing stage, and obtain the actual air pressure at the end of the pre-charging and stabilizing stage;

[0017] Based on the ideal gas law, the effective volume of the polishing chamber is determined by the theoretical feed rate during the pre-charging and stabilization stage, the ideal gas constant, the preset process preheating reference temperature, the actual gas pressure at the end of the pre-charging and stabilization stage, and the molar mass of the organic solvent.

[0018] Furthermore, the specific steps for determining the theoretical feed rate during the gradient pressurization stage are as follows:

[0019] Based on the ideal gas law, the updated target total theoretical feed rate is determined by the target gas pressure corresponding to the plastic part to be polished, the effective volume of the polishing chamber, the molar mass of the organic solvent, the ideal gas constant, and the preset process preheating reference temperature.

[0020] Multiply the preset second adjustment coefficient by the total theoretical feed amount of the updated target, subtract the theoretical feed amount of the pre-charging and stabilizing stage from the product, and record the calculated difference as the theoretical feed amount of the gradient boosting stage.

[0021] Furthermore, the specific steps for determining the theoretical feed rate during the gradient pressurization stage are as follows:

[0022] The ratio of the theoretical feed rate during the gradient pressurization stage to the preset duration of the gradient pressurization stage is denoted as the theoretical feed rate during the gradient pressurization stage.

[0023] Furthermore, the specific steps for determining the gasification efficiency deviation coefficient during the gradient pressurization stage are as follows:

[0024] The sum of the theoretical feed rates of the pre-charge stabilization stage and the gradient pressurization stage is denoted as the total theoretical feed rate of the pre-charge stabilization stage and the gradient pressurization stage.

[0025] Based on the ideal gas law, the theoretical target gas pressure for the gradient pressurization stage is determined by the theoretical total feed rate, ideal gas constant, preset process preheating reference temperature, effective volume of the polishing chamber, and molar mass of the organic solvent.

[0026] The theoretical pressure rise rate of the gradient pressure rise stage is obtained by subtracting the actual pressure at the end of the pre-charge stabilization stage from the theoretical target pressure of the gradient pressure rise stage, and then dividing the difference by the preset duration of the gradient pressure rise stage.

[0027] The actual average pressure rise rate of the gradient pressure rise phase is obtained by subtracting the actual pressure at the end of the pre-charge stabilization phase from the actual pressure at the end of the gradient pressure rise phase, and then dividing the difference by the preset duration of the gradient pressure rise phase.

[0028] The ratio of the actual average pressurization rate to the theoretical pressurization rate during the gradient pressurization stage is denoted as the gasification efficiency deviation coefficient during the gradient pressurization stage.

[0029] Furthermore, the specific steps for determining the target feed rate correction value in the precise pressure compensation stage are as follows:

[0030] The difference between the target air pressure corresponding to the plastic part to be polished and the actual air pressure at the end of the gradient pressurization stage is recorded as the actual air pressure deviation value at the end of the gradient pressurization stage.

[0031] Based on the ideal gas law, the feed amount required for the precise pressurization stage is determined by the actual gas pressure deviation value, the effective volume of the polishing chamber, the molar mass of the organic solvent, the ideal gas constant, the preset process preheating reference temperature, and the gasification efficiency deviation coefficient of the gradient pressurization stage.

[0032] The sum of the theoretical feed rates of the pre-charging and stabilizing stage and the gradient pressurization stage is denoted as the theoretical total feed rate of the pre-charging and stabilizing stage and the gradient pressurization stage; the product of the complement of the gasification efficiency deviation coefficient of the gradient pressurization stage and the theoretical total feed rate is the total amount of condensed material in the precise pressurization stage.

[0033] The total amount of condensed material in the precise pressurization stage is divided by the preset gas release time constant, and then multiplied by the exponential decay correction term to calculate the amount of condensed material re-vaporized at each moment in the precise pressurization stage; the exponential decay correction term is an exponential term with the natural constant as the base and the negative value of the ratio of time to the preset gas release time constant as the exponent.

[0034] Based on the ideal gas law, the predicted pressure increment at each moment in the precise pressure replenishment stage is determined by the amount of condensed material regasified at each moment, the ideal gas constant, the preset process preheating reference temperature, the effective volume of the polishing chamber, and the molar mass of the organic solvent.

[0035] The pressure ratio is obtained by dividing the predicted air pressure increment at the preset termination time of the precise pressure replenishment stage by the difference between the target air pressure corresponding to the plastic part to be polished and the actual air pressure at the end of the gradient pressurization stage. The complement of the pressure ratio is then taken and multiplied by the feed amount required for the precise pressure replenishment stage to obtain the target feed amount correction value for the precise pressure replenishment stage.

[0036] Furthermore, the specific steps for obtaining the initial feed rate control value at each moment during the precise pressure compensation stage are as follows:

[0037] The difference between the target air pressure corresponding to the plastic part to be polished and the predicted air pressure increment at each moment in the precise pressure replenishment stage is denoted as the dynamic target air pressure at each moment in the precise pressure replenishment stage.

[0038] Obtain the actual air pressure at each moment during the precise pressurization phase, and record the difference between the dynamic target air pressure and the actual air pressure at each moment during the precise pressurization phase as the air pressure deviation at each moment during the precise pressurization phase.

[0039] The adaptive proportional value, adaptive integral value, and adaptive derivative value are obtained by multiplying the gain coefficient by the preset proportional value, preset integral value, and preset derivative value, respectively. The gain coefficient is determined by the ideal gas constant, the preset process preheating reference temperature, the effective volume of the polishing chamber, the molar mass of the organic solvent, and the gasification efficiency deviation coefficient of the gradient pressurization stage.

[0040] Based on the adaptive proportional value, adaptive integral value, and adaptive derivative value, and combined with the air pressure deviation at each moment in the precise pressure replenishment stage, PID calculation is performed to output the initial feed rate control quantity at each moment in the precise pressure replenishment stage.

[0041] Furthermore, the specific steps for determining the final feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage are as follows:

[0042] The control is adjusted once every preset control cycle to obtain the feed amount of each control cycle in the precise pressure replenishment stage. The sum of the feed amounts of each control cycle in the precise pressure replenishment stage and all previous control cycles is recorded as the cumulative feed amount of each control cycle in the precise pressure replenishment stage.

[0043] The difference between the target feed rate correction value in the precision pressure replenishment stage and the cumulative feed rate in each control cycle of the precision pressure replenishment stage is recorded as the material difference value in each control cycle of the precision pressure replenishment stage.

[0044] Based on the numerical range of the material difference in each control cycle during the precision pressure replenishment stage relative to the target feed rate correction value of the precision pressure replenishment stage, the maximum allowable feed rate for each control cycle during the precision pressure replenishment stage is determined in segments.

[0045] By limiting the initial feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage to the range of zero to the maximum allowable feed rate, the final feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage is obtained.

[0046] The present invention also proposes an additive manufacturing part surface treatment apparatus using chemical vapor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program stored in the memory to implement the steps of the aforementioned additive manufacturing part surface treatment method using chemical vapor.

[0047] The beneficial effects of the technical solution of the present invention are:

[0048] In this embodiment of the invention, the theoretical feed rate for the pre-charging and stabilizing stage is determined, and feeding is performed. Then, the effective volume of the polishing chamber is determined, thereby determining the theoretical feed rate for the gradient pressurization stage. Feeding is performed, the actual gas pressure at the end of the gradient pressurization stage is obtained, and the gasification efficiency deviation coefficient for the gradient pressurization stage is determined, thereby determining the target feed rate correction value for the precise pressurization stage. The initial feed rate control value at each moment in the precise pressurization stage is obtained. Combined with the target feed rate correction value for the precise pressurization stage, the initial feed rate control value is limited, and the final feed rate control value corresponding to each control cycle in the precise pressurization stage is determined until the heat preservation and pressure holding stage is entered. Under the heat preservation and pressure holding conditions, the surface polishing treatment of the plastic parts to be polished is completed. Thus, this invention indirectly controls the steam concentration through chamber gas pressure, adopts a three-stage gasification control strategy of pre-charging and stabilizing, gradient pressurization, and precise pressurization, and introduces the effective volume and gasification efficiency deviation coefficient to achieve high-precision and high-consistency control of chemical steam concentration, improving the surface polishing effect of plastic parts. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a flowchart illustrating the steps of an additive manufacturing part surface treatment method utilizing chemical vapor according to the present invention.

[0051] Figure 2 A schematic diagram of a system for polishing the surface of plastic parts using chemical vapor.

[0052] Figure 3 A schematic diagram of the external structure of a device for polishing the surface of plastic parts using chemical vapor.

[0053] Figure 4 This is a schematic diagram of the internal structure of the processing device;

[0054] Figure 5 This is a schematic diagram of the rear of the processing device;

[0055] Figure 6 This is a schematic diagram of the bottom structure of the processing device;

[0056] Figure 7 This is a schematic diagram of the structure on the other side of the bottom of the processing device;

[0057] Figure 8 This is a schematic diagram showing the nozzle positions in the processing device;

[0058] Figure 9 Example images of the first type of plastic part before and after chemical vapor polishing;

[0059] Figure 10 Example images of a second type of plastic part before and after chemical vapor polishing;

[0060] Figure 11 Example images of a third type of plastic part before and after chemical vapor polishing. Detailed Implementation

[0061] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an additive manufacturing part surface treatment apparatus and method utilizing chemical vapor according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0063] The following description, in conjunction with the accompanying drawings, details the specific solution of the additive manufacturing part surface treatment apparatus and method utilizing chemical vapor provided by the present invention.

[0064] Please see Figure 1 The diagram illustrates a flowchart of a surface treatment method for additively manufactured parts using chemical vapor, according to an embodiment of the present invention. The method includes the following steps:

[0065] Step S001: Obtain the nominal volume of the polishing chamber, the volume of the plastic part to be polished, the target air pressure corresponding to the plastic part to be polished, and the molar mass of the organic solvent.

[0066] In this embodiment, a schematic diagram of the system structure for polishing the surface of plastic parts using chemical vapor is shown, as follows: Figure 2 As shown. The system structure includes a processing chamber, a vaporization device, a feeding system, reagent bottles, a weighing sensor, a pressure sensor, a vacuum pump, a condenser / liquefier, activated carbon, and five solenoid valves.

[0067] It should be noted that: the processing chamber is a sealed structure, containing at least one door, one steam inlet, one air inlet, and one air outlet. The parts to be polished are placed in the processing chamber for polishing. A pressure sensor is installed in the processing chamber to monitor the internal pressure and feed it back to the control center, which regulates the chamber pressure via a vacuum pump. A weighing sensor is used to detect the remaining solvent in the reagent bottle. The reagent bottle is a solvent storage container, and the condensed and recovered solvent also flows back into the reagent bottle. The reagent bottle is placed above the weighing sensor to detect the remaining solvent. The feeding device is a corrosion-resistant solvent delivery device, which can be a peristaltic pump, plunger pump, or magnetic pump, etc. The vaporization device is a high-efficiency heat exchange device, which includes a heating element, a temperature sensor, a safety temperature limit switch, piping, at least one liquid inlet, and one air outlet. The vacuum pump is used to evacuate the processing chamber, transport the solvent vapor to the condensation and liquefaction device, extract the waste gas from the chamber, purify it through activated carbon adsorption, and then discharge it into the atmosphere. The chemical vapors inside the chamber are pumped to a condenser and liquefied by a vacuum pump, then flow back into the reagent bottles. Solenoid valves are used to control the on / off state of the pipelines and regulate the flow of gas or liquid.

[0068] In this embodiment, example images of the first type of plastic part before and after chemical vapor polishing are provided, such as... Figure 9 As shown; Example images of the second type of plastic part before and after chemical vapor polishing, such as... Figure 10 As shown; Example images of a third type of plastic part before and after chemical vapor polishing, such as... Figure 11 As shown.

[0069] Figure 9 The left side shows a schematic diagram of the part before chemical vapor polishing, and the right side shows a schematic diagram of the part after chemical vapor polishing. Figure 10 and Figure 11 The right side shows a schematic diagram of the part before chemical vapor polishing, and the left side shows a schematic diagram of the part after chemical vapor polishing.

[0070] It should be noted that in this embodiment, basic data acquisition and system initialization are performed first. Addressing the insufficient precision of traditional chemical reagent material quality control methods, chamber pressure control is used to replace traditional quality control. This requires collecting various data related to concentration and pressure, but only core parameters directly related to concentration control are acquired, avoiding redundant data acquisition and ensuring data validity and processability. All parameters are quantifiable and recordable physical quantities with clearly defined data types, and their technical scale is compatible with the control precision requirements of this embodiment. Specifically:

[0071] (1) Acquisition of inherent system parameters:

[0072] The nominal volume of the polishing chamber (processing chamber) for collection. (Unit: L), This parameter is provided by the equipment manufacturer and calibrated at the factory with an accuracy of ±0.01L.

[0073] The actual air pressure (unit: kPa) inside the polishing chamber at every moment is collected. A capacitive pressure sensor with an accuracy of ±0.01 kPa is used for real-time measurement, and the sampling frequency is 10 Hz.

[0074] Collect the molar mass of organic solvents (Unit: g / mol), where the molar mass is the intrinsic constant of the substance, and this parameter is obtained from the standard substance handbook and verified experimentally.

[0075] (2) Collection of relevant parameters of the part:

[0076] Collect the volume of the plastic part to be polished (the part to be processed). (Unit: L), measured by 3D scanning or drainage method (or directly extracted from design documents), with an accuracy of ±0.001L.

[0077] (3) Target parameter setting:

[0078] Based on the initial surface roughness and target surface roughness of the plastic part to be polished, the corresponding target air pressure is retrieved from the material-processing intensity-target air pressure related knowledge base. (Unit: kPa).

[0079] If there is no corresponding record in the knowledge base, an empirical formula will be used for calculation:

[0080]

[0081] in, Material-related proportionality coefficients (unit: ), which belongs to the well-known conventional experience coefficients in the field of process experience modeling; Initial surface roughness of the plastic part to be polished (unit: ), Ra 12 μm; Target surface roughness of the plastic part to be polished (unit: ), Ra 3 μm; Polishing time (unit: ), The value is 300s. This calculation formula is a well-known engineering experience calculation model in the field of surface polishing processes.

[0082] (4) System initialization:

[0083] Close the polishing chamber door and start the vacuum pump to reduce the air pressure inside the chamber to below 30 kPa, and maintain this pressure for 30 seconds to remove any residual air.

[0084] The heating system is activated to preheat the polishing chamber wall temperature and the workpiece temperature to the preset process preheating reference temperature. (Unit: K) The value is 318.15K, and the temperature control accuracy is ±0.5K.

[0085] Initialize the feeding device by heating the organic solvent to its vaporization temperature and ensuring that there are no air bubbles in the feeding pipeline.

[0086] Step S002: Based on the difference between the nominal volume of the polishing chamber and the volume of the plastic part to be polished, and combined with the target air pressure corresponding to the plastic part to be polished and the molar mass of the organic solvent, determine the theoretical feed amount for the pre-charge and stabilization stage; feed materials according to the theoretical feed amount for the pre-charge and stabilization stage to determine the effective volume of the polishing chamber.

[0087] It should be noted that when pure gas pressure closed-loop control is used as the sole control method, the unavoidable vaporization time constant between the organic solvent feed and the chamber pressure response, along with the system's delayed gas release process, leads to continuous oscillations and irreversible overshoot in the control loop. This results in control stability and accuracy that cannot meet the requirements of high-precision surface treatment. Therefore, in this embodiment, the vapor concentration is indirectly controlled by the chamber pressure. A three-stage control strategy of pre-charging stabilization, gradient pressurization, and precise pressurization is adopted, coordinating vaporization concentration and material quality. Furthermore, effective volume and vaporization efficiency deviation coefficients are introduced to achieve high-precision and high-consistency control of the chemical vapor concentration. In other words, precise material control is achieved by controlling the chamber pressure, thereby improving the effect and precision of surface treatment.

[0088] The first step is the pre-charge stabilization stage and effective volume quantification:

[0089] It should be noted that: First, a certain concentration of material is injected into the chamber during the pre-filling and stabilization stage to eliminate the impact of vacuum shock on the workpiece, pre-fill the internal channels of the complex structure with steam, and simultaneously quantify the effective volume of the system to provide accurate volume parameters for subsequent concentration calculations. Under vacuum conditions, the gas pressure generated after a certain mass of pure substance is completely vaporized is inversely proportional to the effective volume. By measuring the actual gas pressure after the vaporization of a known mass of material, the effective volume of the system, i.e., the effective volume of the polishing chamber, can be calculated.

[0090] Calculate the nominal volume of the polishing chamber. Subtract the volume of the plastic part to be polished. The difference , which is denoted as the gas filling volume of the material.

[0091] Determine the target total theoretical feed rate based on the well-known ideal gas law. The specific calculation formula is as follows:

[0092]

[0093] in, is the ideal gas constant, with a value of 8.314. This is a well-known physical constant; The preset preheating reference temperature for the process; The molar mass of the organic solvent; The target air pressure corresponds to the plastic part to be polished.

[0094] The first adjustment factor is set to 0.2, and this will be used as an example for explanation.

[0095] Obtain the theoretical feed rate during the pre-charge and stabilization stage. .

[0096] Start the feeding device and feed the material at a constant rate for 10 seconds, delivering a mass of [missing information]. All organic solvents are sprayed into the vaporization chamber, where they are completely vaporized and enter the polishing chamber. The system is kept sealed, and 10 seconds are allowed for the gas pressure inside the polishing chamber to stabilize. The actual gas pressure after stabilization is recorded as the actual gas pressure at the end of the pre-charging and stabilization phase. .

[0097] The effective volume of the polishing chamber The calculation formula is:

[0098]

[0099] Step S003: Determine the theoretical feed rate for the gradient pressurization stage based on the effective volume of the polishing chamber; determine the theoretical feed rate for the gradient pressurization stage based on the theoretical feed rate; feed materials according to the theoretical feed rate for the gradient pressurization stage and obtain the actual gas pressure at the end of the gradient pressurization stage; determine the gasification efficiency deviation coefficient for the gradient pressurization stage based on the actual gas pressure at the end of the gradient pressurization stage.

[0100] Then, the deviation coefficient between the gradient pressurization stage and the gasification efficiency is calculated:

[0101] It should be noted that during the gradient pressurization phase, the vapor concentration inside the chamber is rapidly increased to near the target value. Simultaneously, the impact of temperature fluctuations and system condensation on vaporization efficiency is quantified, and the vaporization efficiency deviation coefficient is calculated. The vaporization of organic solvents in a vacuum environment is a strongly endothermic process. During the gradient pressurization phase, a continuous uniform feed mode is used to achieve rapid pressurization. The instantaneous vaporization of a large amount of material rapidly absorbs heat from the vaporization chamber, chamber walls, and component surfaces, causing a sudden drop in local temperature. Some material does not have time to completely vaporize and condenses directly on the chamber walls, pipe inner walls, and component surfaces, becoming temporarily ineffective material. This portion of material does not participate in the formation of the current chamber pressure but will slowly re-vaporize as the system temperature gradually recovers, producing a delayed release effect. Under uniform feed conditions, the theoretical pressurization rate inside the chamber should be constant, but the deviation between the actual pressurization rate and the theoretical pressurization rate is essentially caused by the insufficient effective vaporization volume due to the aforementioned condensation. By comparing the deviations between the two and applying temperature correction, the gasification efficiency deviation coefficient under the current operating conditions can be accurately calculated, and the effective gas pressure increment that can be generated per unit mass of feed can be quantified.

[0102] Based on the effective volume obtained above, the theoretical feed rate is recalculated, and the target total theoretical feed rate is updated. The calculation formula is:

[0103]

[0104] The second adjustment factor is preset to 0.9, and this will be used as an example for explanation.

[0105] Obtain the theoretical feed rate during the gradient boost stage. .

[0106] Then obtain the theoretical target air pressure during the gradient pressurization phase. The specific calculation formula is as follows:

[0107]

[0108] in, This represents the theoretical total feed rate for the pre-charging and stabilization phases and the gradient pressurization phases.

[0109] Therefore, the theoretical boost rate during the gradient boost stage The calculation formula is:

[0110]

[0111] It should be noted that the theoretical target air pressure during the gradient pressurization phase is... This is the theoretical pressure that should be reached at the end of the gradient pressurization phase. This represents the actual air pressure at the end of the pre-charging and stabilization phase, and also indicates the actual air pressure at the beginning of the gradient pressurization phase. In this embodiment, the duration of the preset gradient boost phase is... It is 170s.

[0112] Obtain the theoretical feed rate during the gradient boost stage .

[0113] Start the feeding device at the theoretical feed rate of the gradient pressurization stage. The material is fed at a constant speed, and the air pressure data inside the polishing chamber is collected in real time at a sampling frequency of 10Hz. When the feeding time reaches... Stop feeding and wait 10 seconds for the air pressure inside the polishing chamber to stabilize. Record the actual air pressure after stabilization as the actual air pressure at the end of the gradient pressurization stage. .

[0114] The actual average boost rate during the gradient boost phase The calculation formula is:

[0115]

[0116] Therefore, the gasification efficiency deviation coefficient during the gradient pressurization stage The calculation formula is:

[0117]

[0118] It should be noted that the gasification efficiency deviation coefficient is... This reflects the ratio of actual gasification efficiency to theoretical gasification efficiency. When A value less than 1 indicates that the actual gasification efficiency is lower than the theoretical value, meaning that some material has not been completely gasified or has been condensed by the system, requiring precise pressure replenishment afterwards. A value greater than 1 indicates that the actual gasification efficiency is higher than the theoretical gasification efficiency. This is often caused by an abnormal increase in the chamber temperature or a minor system leak, leading to artificially high chamber pressure and excessive steam concentration. In this case, material feeding and pressurization operations should be stopped immediately. A small-flow-rate gradient micro-pressure relief method should be used to restore the chamber pressure to the target pressure range. Simultaneously, the chamber temperature setting should be corrected and potential leaks should be investigated. After the chamber pressure and steam concentration stabilize, the heat preservation and pressure holding stage should begin. Under these conditions, the surface polishing of the plastic parts to be polished should be completed. When the value equals 1, it means that the actual gasification efficiency has reached the theoretical value. Therefore, no further pressurization is required, and the process can directly enter the heat preservation and pressure preservation stage. The surface polishing of the plastic parts to be polished is completed under the heat preservation and pressure preservation conditions.

[0119] Step S004: Based on the magnitude of the gasification efficiency deviation coefficient in the gradient pressurization stage, determine the target feed rate correction value for the precision pressurization stage; obtain the initial feed rate control value at each moment in the precision pressurization stage, and limit the initial feed rate control value in combination with the target feed rate correction value for the precision pressurization stage to determine the final feed rate control value corresponding to each control cycle in the precision pressurization stage, until entering the heat preservation and pressure preservation stage, and complete the surface polishing treatment of the plastic parts to be polished under the heat preservation and pressure preservation conditions.

[0120] Finally, the precise pressure replenishment stage and dual PID dynamic vaporization control are implemented:

[0121] It should be noted that the purpose of the precise pressurization stage is to accurately adjust the steam concentration in the chamber to the target value and maintain its stability throughout the entire process, ensuring the uniformity and consistency of the surface treatment of the parts. This stage uses pneumatic control to dynamically track the pneumatic pressure balance point to precisely control the strength of the surface treatment effect. However, because vaporization causes pressure changes in the chamber during pure pneumatic control, leading to significant fluctuations and overshoot in the vaporization control, this stage embeds dynamic limiting control of accumulated material at the PID output of the vaporization control. By dynamically tightening the upper limit of the control quantity based on the difference between the accumulated feed amount and the target feed amount, it fundamentally suppresses the large fluctuations and irreversible overshoot that easily occur with pure pneumatic control, balancing control accuracy and system stability.

[0122] It should be further explained that: First, the feedforward feed rate is calculated using the parameters obtained in the above stages. The space not occupied by the workpiece in the polishing chamber, the pipeline volume, the vaporization chamber volume, and the volume of the closed pores inside the workpiece are collectively referred to as the dead zone volume. The dead zone volume will cause system deviation, and the deviation in vaporization efficiency will lead to delayed gas release in the subsequent process. Therefore, based on the effective volume and vaporization efficiency deviation coefficient obtained from the calibration in the first two stages after removing the influence of the dead zone volume, the feed rate required for the precise pressure replenishment stage is calculated.

[0123] The required feed volume for the precise pressure replenishment stage The calculation formula is:

[0124]

[0125] in, This represents the actual pressure deviation at the end of the gradient pressurization phase.

[0126] It should be noted that a delayed gas release dynamic model is then constructed. Because the condensate from the rapid pressurization phase described above will gradually volatilize in subsequent stages, resulting in delayed gas release and affecting subsequent pressure control, a decaying gas release model is established by quantifying the total amount of condensate accumulated in the system using the gasification efficiency deviation coefficient. This model predicts the pressure increment caused by the regasification of condensate in the future and adjusts the target feed rate and dynamic target pressure accordingly.

[0127] Total amount of condensed material during the precise pressurization stage The calculation formula is:

[0128]

[0129] It should be noted that: since the regasification process of the condensate follows a first-order exponential decay law, a hysteresis release dynamic model is constructed using a first-order exponential decay, specifically as follows:

[0130]

[0131] in, For the precise pressure replenishment stage The amount of condensed material re-vaporized at any given time. This is the exponential decay correction term. It is a natural constant. The preset gas release time constant (unit: s). Through experimental calibration, it was found that common organic solvents such as acetone and dichloromethane... The value range is 60 to 120 seconds. The specific calibration procedure is as follows:

[0132] (1) Evacuate the polishing chamber to a vacuum of less than 30 kPa, preheat it to the preset process preheating reference temperature, and place the standard sample inside.

[0133] (2) Quickly inject a known mass of organic solvent (approximately 50% of the target total feed amount), immediately shut off the heating system, keep it sealed for 120 seconds, and allow the material to fully condense on the chamber walls, pipelines and sample surface.

[0134] (3) Start the pressure sensor to continuously collect the cabin pressure at a frequency of 10Hz for 600s (covering the complete gas release process) to obtain the pressure-time curve.

[0135] (4) The curve is to be fitted with a first-order exponential function. The reciprocal of the obtained exponential coefficient is the gas release time constant at the preset process preheating reference temperature. .

[0136] By using a hysteresis release dynamic model, the first step in the precise pressurization stage can be obtained. Predicted pressure increment at time The specific calculation formula is as follows:

[0137]

[0138] It should be noted that, to offset the delayed gas release, the target feed rate and dynamic target gas pressure need to be adjusted. The typical duration of the precise pressure replenishment phase is 0.5 to 3 minutes. In this embodiment, the preset duration of the precise pressure replenishment phase is... The duration is 100 seconds. Timing begins at the start of the precise pressure compensation phase and continues for the specified duration. The corresponding time is the preset termination time of the precise pressure replenishment phase. Therefore, the predicted pressure increment at the preset termination time of the precise pressure replenishment phase can be obtained. .

[0139] Target feed rate correction value during the precise pressure replenishment stage The calculation formula is:

[0140]

[0141] Establish a dynamic target pressure curve over time, and in the precise pressurization stage... Dynamic target air pressure at any given time The calculation formula is:

[0142]

[0143] It should be noted that the final step involves PID control with cumulative material dynamic limiting based on air pressure. When tracking the target air pressure, direct PID control using the error between the real-time and target air pressures due to air pressure fluctuations can lead to fluctuations and overshoot in the final control result. Material control, however, is unaffected by air pressure fluctuations. Therefore, cumulative material dynamic limiting is embedded in the air pressure PID output, using the difference between the cumulative feed rate and the target feed rate to suppress overshoot risk. Specifically:

[0144] (1) Based on the system open-loop gain, the parameters of the air pressure PID controller are adaptively tuned to ensure that the stability and response speed of the control loop are consistent under different operating conditions, and the gain coefficient is... The gain coefficient represents the steady-state pressure increment (kPa / g) that can be generated per unit mass of feed.

[0145] It should be noted that the PID controller is a very common and well-known type of controller used to control industrial processes, mechanical systems, and various other systems. PID stands for Proportional, Integral, and Derivative, representing the three main components of the controller.

[0146] (2) Initialization of the air pressure PID controller: The air pressure PID controller uses the dynamic target air pressure as the controlled variable and employs PID control. Its output is the initial feed rate control quantity. In the precise pressure replenishment stage... Initial feed rate control amount at time 1 The calculation formula is:

[0147]

[0148] in, For the precise pressure replenishment stage Pressure deviation at any given time , For the first stage of precise pressure replenishment in the polishing chamber The actual air pressure at that moment. For the precise pressure replenishment phase from time zero to the first The integral cumulative value of the air pressure deviation at time t. For the precise pressure replenishment stage The rate of change of air pressure deviation at any given time. Preset proportional value. The preset integral value is 1.8. The preset differential value is 0.4. The value is 0.09. Therefore, the adaptive scaling value is... Adaptive integral value Adaptive differential value .

[0149] (3) Cumulative material dynamic limit: After the initial control quantity is calculated by the air pressure PID, it is not directly output to the feeding device. Instead, the upper limit of the control quantity is dynamically adjusted by accumulating the material difference, thereby achieving graded suppression of overshoot risk. Specifically:

[0150] First, calculate the cumulative feed amount and preset the control cycle. That is, every interval Perform one adjustment to obtain the first precise pressure replenishment phase. Feed rate per control cycle (Unit: g), which is the difference in material weight (remaining solvent in the reagent bottle) before and after the control cycle, collected by a weighing sensor. Therefore, in the precise pressure replenishment stage... Cumulative feed amount per control cycle ,in For the precise pressure replenishment stage The feed rate for each control cycle.

[0151] Then, calculate the material difference and the limiting coefficient, and calculate the target feed rate correction value for the precise pressure compensation stage. In the precise pressure replenishment stage Cumulative feed amount per control cycle The difference is denoted as the first value in the precise pressure replenishment stage. Material difference per control cycle Based on the magnitude of the material difference, the precise pressure compensation stage of the PID output is adjusted accordingly. Maximum allowable feed rate per control cycle Implement tiered restrictions, specifically:

[0152] The default high coefficient is 0.1 and the default low coefficient is 0.03. This will be used as an example for explanation.

[0153] like ,but ,in This is the system's nominal maximum feed rate.

[0154] like ,but .

[0155] like ,but .

[0156] like ,but .

[0157] It should be noted that: when the cumulative feed rate is far below the target value, the limiting function is ineffective, and the air pressure PID control is completely independent, ensuring rapid response. When the cumulative feed rate approaches the target value, the maximum allowable feed rate is gradually reduced to avoid overshoot caused by PID integral saturation and system lag. When the cumulative feed rate reaches or exceeds the target value, regardless of the air pressure deviation, the feed is forcibly stopped, fundamentally preventing over-etching of parts caused by excessive feed.

[0158] Finally, the final control output is performed, and the air pressure PID is used in the precise pressure compensation stage. The initial feed rate control quantity corresponding to each control cycle Limited to Within the range, the first stage of precise pressure replenishment was obtained. The final feed rate control quantity corresponding to each control cycle ,in To find the maximum value function, This is a function that takes the minimum value.

[0159] (4) The real-time control process for the precise pressure replenishment stage is as follows:

[0160] (4.1) Start the precise pressure replenishment stage timer, with the initial time being 0, the cumulative feed amount being initialized to 0, and the air pressure PID controller being initialized.

[0161] (4.2) Calculate the dynamic target air pressure at the current moment. Pressure deviation .

[0162] (4.3) The air pressure PID controller is based on Calculate the initial feed rate control value at the current moment. .

[0163] (4.4) Calculate the cumulative feed amount at the current time. Difference between material Determine the maximum allowable feed rate at the current moment. .

[0164] (4.5) By limiting the amplitude, the final feed rate control value at the previous time step is obtained. Control the feeding of the feeding device.

[0165] (4.6) Update the cumulative feed amount and add 1 control cycle to the timer.

[0166] (4.7) Repeat (4.1) to (4.6) above until any of the following stopping conditions are met, stop feeding, enter the heat preservation and pressure preservation stage, and complete the surface polishing treatment of the plastic parts to be polished under the heat preservation and pressure preservation conditions.

[0167] Condition 1: At the current moment, the cumulative feed amount reaches Furthermore, the actual air pressure collected inside the polishing chamber is different from the target air pressure. The absolute value of the difference is less than 0.005 kPa;

[0168] Condition 2: The total duration of the precise pressure replenishment phase reaches the preset precise pressure replenishment phase duration. .

[0169] It should be noted that: In this embodiment, the system parameters include a nominal volume of 100L for the polishing chamber (processing chamber), the material of the plastic part to be polished is nylon 12 (PA2200), a rectangular plate with a shape of 100mm×200mm×3mm, and the model is EOS P396; the environmental parameters include an ambient temperature of 28℃ and an ambient air pressure of 101kPa; the part-related parameters include a volume of 60cm³ and a surface area of ​​526cm² for the plastic part to be polished; the reagent parameters include a reagent composition of 90% HFIP and 10% TFP, and a vaporization flow rate of 10mL / s; the target parameters include an untreated surface roughness of Ra 12 μm, a target roughness of Ra 3μm, and the corresponding air pressure conditions for the target roughness are: first, a vacuum is drawn to 30kPa, and then the pressure is raised to 65kPa through reagent vaporization; the process parameters include a polishing time of 300s, a solvent recovery time of 180s, and a purification time of 3600s. The parameters for three repeated chemical vapor polishing processes are as follows: First result: reagent consumption 102g, reagent recovery 28g, surface roughness of the plastic part to be polished Ra 3 μm; Second result: reagent consumption 101g, reagent recovery 29g, surface roughness of the plastic part to be polished Ra 3 μm; Third result: reagent consumption 101g, reagent recovery 28g, surface roughness of the plastic part to be polished Ra 3 μm.

[0170] Further explanation is needed: A control experiment was conducted. Under the premise that system parameters, environmental parameters, part-related parameters, and process parameters remained unchanged, the target parameters for existing chemical vapor polishing were set as follows: untreated surface roughness Ra 12 μm, target roughness Ra 3 μm, and target reagent mass 100 g. The results of three repeated control chemical vapor polishing experiments were as follows: First control results included: reagent consumption 100 g, reagent recovery 29 g, and surface roughness of the plastic part to be polished Ra 3 μm; Second control results included: reagent consumption 103 g, reagent recovery 27 g, and surface roughness of the plastic part to be polished Ra 3 μm; Third control results included: reagent consumption 105 g, reagent recovery 25 g, and surface roughness of the plastic part to be polished Ra 3 μm.

[0171] Compared with the results of multiple sets of control experiments, the reagent consumption and reagent recovery of this embodiment fluctuated less in multiple experiments, and the process parameters and polishing effect were more stable.

[0172] This invention also provides a surface treatment apparatus for additively manufactured parts using chemical vapor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program stored in the memory to implement the steps of the aforementioned surface treatment method for additively manufactured parts using chemical vapor. Specifically:

[0173] In this embodiment, an external schematic diagram of the device for polishing the surface of plastic parts using chemical vapor is shown. Figure 3 As shown; a schematic diagram of the internal structure of the processing device, as shown. Figure 4 As shown; a schematic diagram of the rear side of the processing device, as shown. Figure 5 As shown; a schematic diagram of the bottom structure of the processing device, as shown. Figure 6 As shown; a schematic diagram of the structure on the other side of the bottom of the processing device, as shown. Figure 7 As shown; a schematic diagram of the nozzle positions in the processing device, as shown. Figure 8 As shown.

[0174] exist Figures 3 to 8 In the diagram: 01 is the processing chamber door; 02 is the reagent chamber door; 03 is the display screen; 04 is the chamber door lock; 05 is the power button; 06 is the equipment power cord; 071 and 072 are cooling fans; 08 is the exhaust port; 11 is the reagent bottle; 12 is the vaporization device; 13 is the feeding device; 14 is the condenser / liquefier; 15 is the vacuum pump; 16 is the activated carbon adsorber; 171 is solenoid valve 1; 172 is solenoid valve 2; 173 is solenoid valve 3; 174 is solenoid valve 4; 175 is solenoid valve 5; 181 is the weighing sensor; 182 is the air pressure sensor; 19 is the processing chamber; 20 is the nozzle.

[0175] It should be noted that the specific processing procedure for the chemical vapor polishing device for plastic parts is as follows: Open reagent chamber door 02, add solvent to reagent bottle 11, and open processing chamber door 01; place several parts to be polished into processing chamber 19, close processing chamber door 01, and lock the door lock 04; connect the device power cord 06 to the device power supply, turn on the power button 05, and simultaneously start cooling fans 071 and 072; the user inserts a memory card containing the 3D model of the parts to be polished into the SD card slot of the processing module, and uploads the 3D model to the processing module; it should be noted that the processing module's memory stores several existing 3D model libraries, and the user can decide whether to agree to upload the 3D model of the parts to be polished to the 3D model library; open Solenoid valve 173 is activated to turn on vacuum pump 15 and evacuate the processing chamber 19 to a vacuum. After reaching the required vacuum level, vacuum pump 15 and solenoid valve 173 are turned off. The vaporization device 12 is heated to the evaporation temperature of the chemical solvent and maintained at that temperature. Solenoid valve 171 is opened to draw the chemical solvent from reagent bottle 11 into vaporization device 12 through feeding device 13. After vaporization, the solvent enters the processing chamber 19 through nozzles 20. Since the temperature of the vapor is higher than the temperature of the parts (room temperature), the vapor condenses and liquefies on the surface of the parts, forming a thin liquid film that corrodes and levels the pores of the parts. The amount of solvent supplied is controlled by weighing sensor 181, feeding device 13, and solenoid valve 171. After the supply is completed, solenoid valve 171 is turned off.

[0176] Further explanation is needed regarding the solvent recovery process: Open solenoid valves 172 (No. 2) and 175 (No. 5), run vacuum pump 15 for solvent recycling. The vapor is liquefied in condenser 14 and returned to reagent bottle 11 until the reading on weighing sensor 181 of reagent bottle 11 stops rising, indicating recovery is complete. Then close solenoid valves 172 (No. 2) and 175 (No. 5). The exhaust gas purification process is as follows: Open exhaust port 08, open solenoid valves 174 (No. 4) and 173 (No. 3), run vacuum pump 15. Air enters treatment chamber 19 and is extracted by vacuum pump 15. A small amount of residual solvent vapor inside treatment chamber 19 is drawn into activated carbon filter 16 for adsorption before being discharged into the atmosphere. All solenoid valves and vacuum pump 15 are then closed. After purification, open solenoid valve 174, allowing air to enter treatment chamber 19. The pressure inside the treatment chamber is restored to normal pressure via pressure sensor 182, indicating treatment is complete. Turn off power button 05, turn off cooling fans 071 and 072, close exhaust port 08, unlock hatch 04, open processing hatch 01 and remove all parts to be polished. Display screen 03 can display the processing time of the processing device in real time.

[0177] This invention is now complete.

[0178] In summary, in this embodiment of the invention, the theoretical feed rate for the pre-charging and stabilizing stage is determined, and feeding is performed accordingly. Then, the effective volume of the polishing chamber is determined, thereby determining the theoretical feed rate for the gradient pressurization stage. Feeding is then performed, and the actual gas pressure at the end of the gradient pressurization stage is obtained. Next, the vaporization efficiency deviation coefficient for the gradient pressurization stage is determined, thereby determining the target feed rate correction value for the precise pressurization stage. The initial feed rate control value at each moment in the precise pressurization stage is obtained. Combined with the target feed rate correction value for the precise pressurization stage, the initial feed rate control value is limited, and the final feed rate control value corresponding to each control cycle in the precise pressurization stage is determined until the heat preservation and pressure holding stage is entered. Under heat preservation and pressure holding conditions, the surface polishing treatment of the plastic parts to be polished is completed. This invention achieves high-precision and high-consistency control of chemical vapor concentration, improving the surface polishing effect of plastic parts.

[0179] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for surface treatment of additively manufactured parts using chemical vapor, characterized in that, The method includes the following steps: Obtain the nominal volume of the polishing chamber, the volume of the plastic part to be polished, the target air pressure corresponding to the plastic part to be polished, and the molar mass of the organic solvent; Based on the difference between the nominal volume of the polishing chamber and the volume of the plastic part to be polished, combined with the target air pressure of the plastic part to be polished and the molar mass of the organic solvent, the theoretical feed rate for the pre-charging and stabilizing stage is determined; the material is fed according to the theoretical feed rate for the pre-charging and stabilizing stage to determine the effective volume of the polishing chamber. Based on the effective volume of the polishing chamber, determine the theoretical feed rate for the gradient pressurization stage; based on the theoretical feed rate for the gradient pressurization stage, determine the theoretical feed rate for the gradient pressurization stage; feed according to the theoretical feed rate for the gradient pressurization stage, and obtain the actual gas pressure at the end of the gradient pressurization stage; based on the actual gas pressure at the end of the gradient pressurization stage, determine the gasification efficiency deviation coefficient for the gradient pressurization stage. Based on the magnitude of the gasification efficiency deviation coefficient during the gradient pressurization stage, the target feed rate correction value for the precision pressurization stage is determined. The initial feed rate control value at each moment during the precision pressurization stage is obtained. Combined with the target feed rate correction value for the precision pressurization stage, the initial feed rate control value is limited to determine the final feed rate control value corresponding to each control cycle during the precision pressurization stage, until the heat preservation and pressure preservation stage is entered. Under the heat preservation and pressure preservation conditions, the surface polishing treatment of the plastic parts to be polished is completed.

2. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps for determining the theoretical feed rate during the pre-charging and stabilization stage are as follows: The difference between the nominal volume of the polishing chamber and the volume of the plastic part to be polished is recorded as the material gas filling volume. Based on the ideal gas law, the target total theoretical feed rate is determined by the target gas pressure corresponding to the plastic part to be polished, the gas filling volume of the material, the molar mass of the organic solvent, the ideal gas constant, and the preset process preheating reference temperature. The product of the target total theoretical feed rate and the preset first adjustment coefficient is denoted as the theoretical feed rate during the pre-charging and stabilization stage.

3. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps for determining the effective volume of the polishing chamber are as follows: Feed materials according to the theoretical feed rate during the pre-charging and stabilizing stage, and obtain the actual air pressure at the end of the pre-charging and stabilizing stage; Based on the ideal gas law, the effective volume of the polishing chamber is determined by the theoretical feed rate during the pre-charging and stabilization stage, the ideal gas constant, the preset process preheating reference temperature, the actual gas pressure at the end of the pre-charging and stabilization stage, and the molar mass of the organic solvent.

4. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps for determining the theoretical feed rate during the gradient pressurization stage are as follows: Based on the ideal gas law, the updated target total theoretical feed rate is determined by the target gas pressure corresponding to the plastic part to be polished, the effective volume of the polishing chamber, the molar mass of the organic solvent, the ideal gas constant, and the preset process preheating reference temperature. Multiply the preset second adjustment coefficient by the total theoretical feed amount of the updated target, subtract the theoretical feed amount of the pre-charging and stabilizing stage from the product, and record the calculated difference as the theoretical feed amount of the gradient boosting stage.

5. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps for determining the theoretical feed rate during the gradient pressurization stage are as follows: The ratio of the theoretical feed rate during the gradient pressurization stage to the preset duration of the gradient pressurization stage is denoted as the theoretical feed rate during the gradient pressurization stage.

6. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 3, characterized in that, The specific steps for determining the gasification efficiency deviation coefficient during the gradient pressurization stage are as follows: The sum of the theoretical feed rates of the pre-charge stabilization stage and the gradient pressurization stage is denoted as the total theoretical feed rate of the pre-charge stabilization stage and the gradient pressurization stage. Based on the ideal gas law, the theoretical target gas pressure for the gradient pressurization stage is determined by the theoretical total feed rate, ideal gas constant, preset process preheating reference temperature, effective volume of the polishing chamber, and molar mass of the organic solvent. The theoretical pressure rise rate of the gradient pressure rise stage is obtained by subtracting the actual pressure at the end of the pre-charge stabilization stage from the theoretical target pressure of the gradient pressure rise stage, and then dividing the difference by the preset duration of the gradient pressure rise stage. The actual average pressure rise rate of the gradient pressure rise phase is obtained by subtracting the actual pressure at the end of the pre-charge stabilization phase from the actual pressure at the end of the gradient pressure rise phase, and then dividing the difference by the preset duration of the gradient pressure rise phase. The ratio of the actual average pressurization rate to the theoretical pressurization rate during the gradient pressurization stage is denoted as the gasification efficiency deviation coefficient during the gradient pressurization stage.

7. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps involved in determining the target feed rate correction value for the precise pressure replenishment stage are as follows: The difference between the target air pressure corresponding to the plastic part to be polished and the actual air pressure at the end of the gradient pressurization stage is recorded as the actual air pressure deviation value at the end of the gradient pressurization stage. Based on the ideal gas law, the feed amount required for the precise pressurization stage is determined by the actual gas pressure deviation value, the effective volume of the polishing chamber, the molar mass of the organic solvent, the ideal gas constant, the preset process preheating reference temperature, and the gasification efficiency deviation coefficient of the gradient pressurization stage. The sum of the theoretical feed rates of the pre-charging and stabilizing stage and the gradient pressurization stage is denoted as the theoretical total feed rate of the pre-charging and stabilizing stage and the gradient pressurization stage; the product of the complement of the gasification efficiency deviation coefficient of the gradient pressurization stage and the theoretical total feed rate is the total amount of condensed material in the precise pressurization stage. The total amount of condensed material in the precise pressurization stage is divided by the preset gas release time constant, and then multiplied by the exponential decay correction term to calculate the amount of condensed material re-vaporized at each moment in the precise pressurization stage; the exponential decay correction term is an exponential term with the natural constant as the base and the negative value of the ratio of time to the preset gas release time constant as the exponent. Based on the ideal gas law, the predicted pressure increment at each moment in the precise pressure replenishment stage is determined by the amount of condensed material regasified at each moment, the ideal gas constant, the preset process preheating reference temperature, the effective volume of the polishing chamber, and the molar mass of the organic solvent. The pressure ratio is obtained by dividing the predicted air pressure increment at the preset termination time of the precise pressure replenishment stage by the difference between the target air pressure corresponding to the plastic part to be polished and the actual air pressure at the end of the gradient pressurization stage. The complement of the pressure ratio is then taken and multiplied by the feed amount required for the precise pressure replenishment stage to obtain the target feed amount correction value for the precise pressure replenishment stage.

8. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 7, characterized in that, The specific steps for obtaining the initial feed rate control value at each moment in the precise pressure compensation stage are as follows: The difference between the target air pressure corresponding to the plastic part to be polished and the predicted air pressure increment at each moment in the precise pressure replenishment stage is denoted as the dynamic target air pressure at each moment in the precise pressure replenishment stage. Obtain the actual air pressure at each moment during the precise pressurization phase, and record the difference between the dynamic target air pressure and the actual air pressure at each moment during the precise pressurization phase as the air pressure deviation at each moment during the precise pressurization phase. The adaptive proportional value, adaptive integral value, and adaptive derivative value are obtained by multiplying the gain coefficient by the preset proportional value, preset integral value, and preset derivative value, respectively. The gain coefficient is determined by the ideal gas constant, the preset process preheating reference temperature, the effective volume of the polishing chamber, the molar mass of the organic solvent, and the gasification efficiency deviation coefficient of the gradient pressurization stage. Based on the adaptive proportional value, adaptive integral value, and adaptive derivative value, and combined with the air pressure deviation at each moment in the precise pressure replenishment stage, PID calculation is performed to output the initial feed rate control quantity at each moment in the precise pressure replenishment stage.

9. The surface treatment method for additive manufacturing parts using chemical vapor according to claim 1, characterized in that, The specific steps for determining the final feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage are as follows: The control is adjusted once every preset control cycle to obtain the feed amount of each control cycle in the precise pressure replenishment stage. The sum of the feed amounts of each control cycle in the precise pressure replenishment stage and all previous control cycles is recorded as the cumulative feed amount of each control cycle in the precise pressure replenishment stage. The difference between the target feed rate correction value in the precision pressure replenishment stage and the cumulative feed rate in each control cycle of the precision pressure replenishment stage is recorded as the material difference value in each control cycle of the precision pressure replenishment stage. Based on the numerical range of the material difference in each control cycle during the precision pressure replenishment stage relative to the target feed rate correction value of the precision pressure replenishment stage, the maximum allowable feed rate for each control cycle during the precision pressure replenishment stage is determined in segments. By limiting the initial feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage to the range of zero to the maximum allowable feed rate, the final feed rate control amount corresponding to each control cycle in the precise pressure replenishment stage is obtained.

10. A surface treatment apparatus for additively manufactured parts using chemical vapor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by the processor, it implements the steps of the surface treatment method for additive manufacturing parts using chemical vapor as described in any one of claims 1-9.

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