An on-line directed deposition method of a die lubricant for vacuum isothermal forging

Abstract

The application discloses an online directional deposition method for a die lubricant of vacuum isothermal forging, and relates to the technical field of vacuum isothermal forging die lubrication. An independent coating cabin is arranged in a vacuum isothermal forging furnace, a forging gap is used to move a die into the coating cabin to be grounded and sealed, process gas is filled into the coating cabin to build an environment meeting the requirements of a stable high-voltage electrostatic field, ultrasonic high-frequency mechanical vibration is used to atomize glass lubricant into micron-sized droplets, the droplets are charged based on induction and corona combined charging through the high-voltage electrostatic field, and the droplets are directionally deposited on the surface of the die under the action of coulomb force; after the deposition is completed, the coating cabin is vacuumized, and the die is moved back to a forging station. The application realizes online lubrication coating of the die in the vacuum isothermal forging process, and improves the continuity of forging processing.

Description

Technical Field

[0001] This invention relates to the field of vacuum isothermal forging die lubrication technology, specifically to an online directional deposition method for a lubricant in vacuum isothermal forging dies. Background Technology

[0002] Vacuum isothermal forging is performed at 10 -4 This precision plastic forming process is performed under high vacuum conditions of ~50Pa and high temperature conditions of 800~1200℃. The entire process from heating the billet to forging takes place in a sealed vacuum chamber, and the billet and the die are kept at the same temperature during forging. This process is particularly suitable for preparing key components of aero-engines made of difficult-to-deform materials such as powder metallurgy superalloys and titanium-aluminum alloys, such as turbine disks, compressor disks, and blades.

[0003] In vacuum isothermal forging, due to the large tonnage of the press, low strain rate, and single-pass deformation time of several minutes to tens of minutes, coupled with the consistently high temperatures of the die and billet (800-1200℃), the metal billet and die are highly susceptible to adhesive wear under high temperature and pressure, severely affecting the surface quality of the forgings and the service life of the die. Therefore, applying glass lubricant between the billet and the die is a key technical step in achieving high-quality forming.

[0004] Currently, the glass lubricant widely used in vacuum isothermal forging is a glass protective lubricant with amorphous glass as the main solid base. The glass lubricant typically consists of a slurry composed of glass powder, organic solvents, organic binders, and fillers, which is pre-coated onto the surface of the billet at room temperature. During the forging heating process, the glass slurry undergoes a phase transition process involving the volatilization of organic components, glass softening, and melting, ultimately forming a continuous and dense glass film on the surface of the metal billet. This film serves to isolate the metal surface from the mold and lubricate the surface, reducing the coefficient of friction.

[0005] Existing lubrication coating methods for vacuum isothermal forging mainly fall into two categories, but both suffer from fundamental technical defects: One method is the pre-coating of the blank: before the blank enters the vacuum chamber, a glass lubricant slurry is pre-coated onto the surface of the blank by brushing, spraying, or dipping. After drying, it is placed into the vacuum chamber along with the blank for heating and forging. The drawback of this method is that the glass lubricant is only pre-applied to the surface of the blank. During the forging process, the glass lubricant on the surface of the die will be gradually lost due to high temperature and high pressure shearing, and cannot be replenished in real time. This leads to insufficient lubrication in the later stages of multi-pass forging, resulting in a significant increase in the coefficient of friction.

[0006] The second method is external pre-coating: before the mold is assembled and enters the vacuum chamber, glass lubricant is applied to the working surface of the mold. The drawback of this method is that the vacuum isothermal forging temperature is as high as 800~1200℃, and the pre-coated glass lubricant will flow, decompose and evaporate during the long-term heating and holding process, and cannot be replenished in real time.

[0007] In summary, existing technologies cannot achieve online lubrication coating of the die during vacuum isothermal forging, nor can they replenish the die with lubricant. This directly affects the continuity and stability of multiple processes and forging production. Summary of the Invention

[0008] The purpose of this invention is to provide an online directional deposition method for mold lubricant in vacuum isothermal forging, in order to solve the problem that existing technologies are difficult to achieve online lubrication coating on the mold during vacuum isothermal forging, and to replenish the mold lubricant, which directly affects the continuity and stability of multiple processes and forging production.

[0009] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: This invention provides an online directional deposition method for mold lubricant in vacuum isothermal forging, comprising the following steps: S1. A coating chamber is set up inside a vacuum isothermal forging furnace; and a robotic arm for providing glass lubricant is set up inside the coating chamber, and an ultrasonic atomizing nozzle for ultrasonic atomization treatment of glass lubricant is assembled on the robotic arm. S2. Maintain the initial environment inside the coating chamber consistent with the environment inside the vacuum isothermal forging furnace. After moving the lower mold of the mold to the grounding position inside the coating chamber, seal the coating chamber. S3. Introduce process gas into the coating chamber to create a process environment that can meet the requirements of a stable high-voltage electrostatic field. S4. After the robotic arm moves and the ultrasonic atomizing nozzle is directed toward the mold and moved to a preset position, the glass lubricant is atomized into micron-sized droplets by ultrasonic high-frequency mechanical vibration. S5. A high-voltage electrostatic field is constructed in the region from the ultrasonic atomizing nozzle to the mold, and the droplets acquire charge based on induced charging and corona charging technology. The high-voltage electrostatic field is configured to apply a Coulomb force to drive the charged droplets to be deposited directionally from the ultrasonic atomizing nozzle to the location of the glass lubricant to be coated in the lower mold. S6. After the glass lubricant is deposited, the coating chamber is evacuated so that the pressure inside the coating chamber is close to the pressure inside the vacuum isothermal forging furnace. S7. Open the coating chamber, remove the lower mold from the coating chamber and return it to the furnace chamber.

[0010] According to one embodiment of the present invention, the process gas is air.

[0011] According to one embodiment of the present invention, the high-voltage electrostatic field adopts a negative high voltage; the voltage range is -8 to -3kV.

[0012] According to one embodiment of the present invention, the single directional deposition time is 10 to 60 seconds, so as to ensure sufficient deposition on the mold surface while adapting to the forging production cycle.

[0013] According to one embodiment of the present invention, a method for supplying glass lubricant slurry to the ultrasonic atomizing nozzle includes: storing the glass lubricant slurry in a sealed storage tank, the sealed storage tank being connected to the coating chamber via a vacuum pipeline, so that the pressure inside the sealed storage tank is consistent with the pressure inside the coating chamber; providing a transition cavity between the outlet of the sealed storage tank and the ultrasonic atomizing nozzle, and maintaining the pressure difference between the transition cavity and the ultrasonic atomizing nozzle at 1000~5000Pa through a differential pressure overflow valve; supplying liquid to the ultrasonic atomizing nozzle by a liquid supply device at a set flow rate; and providing a dual redundant isolation valve between the sealed storage tank and the coating chamber for cutting off the air path between the sealed storage tank and the coating chamber during replenishment, so that the sealed storage tank returns to normal pressure before replenishment.

[0014] According to one embodiment of the present invention, the robotic arm moves along a preset path and adjusts the distance between the ultrasonic atomizing nozzle and the mold surface in real time according to the curvature of the mold surface: the greater the curvature, the greater the distance of the ultrasonic atomizing nozzle; the smaller the curvature, the smaller the distance of the ultrasonic atomizing nozzle, so that the distance is always maintained within the range of 30~80mm, so as to counteract the electric field distortion caused by the curvature, maintain a uniform electric field intensity, and ensure consistent deposition thickness.

[0015] According to one embodiment of the present invention, after directional deposition is completed, the electrostatic field is kept in place for 5 to 10 seconds; then the residual charge of the electrostatic field is released.

[0016] According to one embodiment of the present invention, for complex molds with cavities deeper than 50 mm and minimum corner radius less than 5 mm, a layered directional deposition strategy is adopted: first, the ultrasonic atomizing nozzle is moved to a first position to cover the entire cavity opening for directional deposition; then, the ultrasonic atomizing nozzle is moved to a second position to cover the bottom and sidewalls of the cavity for localized fixed-point directional deposition; finally, the ultrasonic atomizing nozzle is moved to a third position to cover the rounded corner area for localized fixed-point directional deposition.

[0017] According to one embodiment of the present invention, the ultrasonic atomizing nozzle applies the high-frequency mechanical vibration of the ultrasonic waves to the glass lubricant slurry supplied to the atomizing plane, causing the slurry to form capillary waves on the surface of the atomizing plane; when the vibration amplitude reaches a critical value, the liquid film tears at the wave crest to form droplets; by adjusting the matching relationship between the slurry flow rate supplied to the atomizing plane and the ultrasonic vibration frequency, a stable atomization state is maintained within a liquid supply flow rate range of 0.01~10mL / min.

[0018] According to one embodiment of the present invention, after directional deposition is completed, a self-cleaning step is automatically performed, in which cleaning solvent is injected at a flow rate of 2 to 3 times the working flow rate to rinse the ultrasonic atomizing nozzle and pipeline for 30 to 120 seconds; when an abnormality in the transducer resonant frequency or impedance is detected, pulse cleaning or backflushing is triggered; after directional deposition is completed, a laser triangular displacement sensor is used to measure the height difference before and after directional deposition on the mold surface to obtain the thickness distribution of the lubricating layer; ultraviolet fluorescence imaging and machine vision algorithms are used to detect the lubricating layer coverage area to obtain coverage data; based on the thickness distribution and coverage data, the directional deposition parameters for the next pass are automatically adjusted, including the liquid supply flow rate, scanning speed and nozzle height, to achieve closed-loop control.

[0019] Compared with the prior art, the present invention has the following advantages: This embodiment provides an online directional deposition method for mold lubricant. It mainly achieves droplet atomization in a high-temperature vacuum isothermal forging furnace and uses electrostatic deposition to achieve the online coating process of glass lubricant. This method can replenish the lubricant of the mold in the vacuum isothermal forging furnace in real time, so as to ensure the continuity between multiple processes and production, thereby ensuring the performance of mold forging products and improving the service life of the mold. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating an online directional deposition method for a mold lubricant in vacuum isothermal forging, as provided in an embodiment of this application.

[0022] Figure 2 A simplified schematic diagram of the overall structure of a dedicated system for the online directional deposition method of lubricant for vacuum isothermal forging dies provided in this application embodiment.

[0023] The reference numerals in the figure are as follows: 100 Lower mold; 200 Coating chamber; 300 Ultrasonic atomizing nozzle; 310 Sealed storage tank; 320 Transition chamber; 330 Differential pressure relief valve; 340 Dual redundant isolation valve; 400 Dual annular electrodes; 500 High-voltage DC power supply; 700 Control unit; 800 Multi-degree-of-freedom robotic arm; 810 End effector; 820 Drive motor; 830 Transmission mechanism. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] like Figure 1 As shown, this application provides an online directional deposition method for mold lubricant in vacuum isothermal forging, which mainly includes the following steps: S1. A coating chamber is set up inside a vacuum isothermal forging furnace; and a robotic arm for providing glass lubricant is set up inside the coating chamber, and an ultrasonic atomizing nozzle for ultrasonic atomization treatment of glass lubricant is assembled on the robotic arm. S2. Maintain the initial environment inside the coating chamber consistent with the environment inside the vacuum isothermal forging furnace. After moving the lower mold of the mold to the grounding position inside the coating chamber, seal the coating chamber. S3. Introduce process gas into the coating chamber to create a process environment that can meet the requirements of a stable high-voltage electrostatic field. S4. After the robotic arm moves and the ultrasonic atomizing nozzle is directed toward the mold and moved to a preset position, the glass lubricant is atomized into micron-sized droplets by ultrasonic high-frequency mechanical vibration. S5. A high-voltage electrostatic field is constructed in the region from the ultrasonic atomizing nozzle to the mold, and the droplets acquire charge based on induced charging and corona charging technology. The high-voltage electrostatic field is configured to apply a Coulomb force to drive the charged droplets to be deposited directionally from the ultrasonic atomizing nozzle to the location of the glass lubricant to be coated in the lower mold. S6. After the glass lubricant is deposited, the coating chamber is evacuated so that the pressure inside the coating chamber is close to the pressure inside the vacuum isothermal forging furnace. S7. Open the coating chamber, remove the lower mold from the coating chamber and return it to the furnace chamber.

[0026] This embodiment provides an online directional deposition method for mold lubricants, primarily addressing the difficulty of online lubricant coating within high-temperature vacuum isothermal forging furnaces. By achieving droplet atomization within the furnace and utilizing electrostatic deposition to perform the online coating process of glass lubricant, the lubricant for the molds within the vacuum isothermal forging furnace can be replenished in real-time. This ensures continuity between multiple processes and in production, thereby guaranteeing the performance of forged products and extending the mold's service life.

[0027] It should be noted that the vacuum isothermal forging furnace is at 10 -4 The process is carried out under conditions of ~50Pa high vacuum and 800~1200℃ high temperature. Therefore, the glass lubricant selected can basically maintain its original properties under this environment and will not produce vaporization or other phenomena.

[0028] In addition, the atomization technology of the glass lubricant can be any method that can be achieved in this vacuum high-temperature environment, preferably by achieving its online atomization through high-frequency mechanical vibration.

[0029] The challenge in this embodiment lies in achieving electrostatic deposition. Considering the high temperature and pressure environment, constructing a stable high-voltage electrostatic field requires a specific gaseous environment, and in 10... -4 In a high vacuum environment of ~50Pa, it is difficult to maintain a stable high-voltage electrostatic field.

[0030] To address this, this implementation method primarily involves constructing an independent coating chamber within the vacuum forging furnace. The coating chamber can be connected to the internal environment of the vacuum forging furnace when not in operation, and can be sealed during operation. Process gases (specifically, gases sufficient to achieve corona discharge while avoiding oxidation of the mold, such as selecting a low-oxygen mixed gas) can be injected into it.

[0031] Specifically, the goal of injecting process gas is to raise the gas environment inside the coating chamber to a high-pressure environment of 100 Pa to 200 Pa (the gas environment can undergo relatively stable ionization), while using the combination of induced charging and corona charging technologies to achieve the stable construction of a high-voltage electrostatic field.

[0032] The high-voltage electrostatic field is mainly achieved through ring electrodes, and at least some of the ring electrodes have pointed structures at their edges so that corona discharge can occur under conditions of sufficient gas molecule density.

[0033] Normally, the coating chamber itself is not very large. When the injection of process gas increases the pressure inside the chamber to 100 Pa to 200 Pa, the effect on the temperature of the coating chamber is not significant and can be ignored.

[0034] After the directional deposition is completed, the gas environment in the coating chamber is evacuated again to maintain a state that is basically consistent with the environment inside the vacuum forging furnace, so as to avoid a significant impact on the vacuum forging furnace (the slight impact caused by factors such as airtightness can be ignored on the entire vacuum forging furnace).

[0035] One such mechanism is to install a guide rail, similar to the one used for the mold entering the forging furnace from the outside, as a motion mechanism for entering the coating chamber within the vacuum forging furnace.

[0036] During forging intervals or breaks in continuous production, the lower die automatically moves along the guide rail mechanism to the grounded position inside the coating chamber. The electrically controlled sealing door of the coating chamber is then closed. The coating chamber can also be equipped with a temperature control structure to maintain the internal temperature, ensuring that the temperature drop during die transfer does not exceed 50℃~100℃.

[0037] The robotic arm carries the ultrasonic atomizing nozzle to a preset position. The ultrasonic generator and liquid supply device are activated, and a high-voltage electrostatic field is applied simultaneously. After the droplets are atomized and charged, they are directionally deposited onto the mold surface under the action of Coulomb force. After deposition is complete, the ultrasonic generator and liquid supply device are turned off, and the coating chamber is evacuated to the same pressure as the forging cavity. The electrically controlled sealing door is opened, and the lower mold automatically moves back to the forging station.

[0038] The droplet flight time is extremely short, and it will not evaporate prematurely due to high temperature. Under the action of electrostatic field, the flight speed of glass lubricant droplets of 1~20μm is 10~20m / s. The distance between the nozzle and the mold surface is controlled at 30~80mm. Therefore, the total flight time of the droplet from the nozzle outlet to the mold surface is only 1.5~8ms.

[0039] According to D 2 According to the law of evaporation, at 1200℃, it takes approximately 120 ms for a 10 μm diameter glass lubricant droplet to completely evaporate, which is 15 to 80 times the actual flight time. Experiments show that the amount of organic solvent that evaporates during flight accounts for only 5 to 10% of the total mass, and the remaining 90% or more of the glass powder can be effectively deposited on the mold surface to form a continuous lubricating film.

[0040] This method enables online directional deposition of mold lubricant during vacuum isothermal forging, solving the problems of existing technologies where atomization relies on gaseous media that disrupt the vacuum environment and cannot achieve uniform online deposition during forging gaps.

[0041] The coating process is completed entirely within the forging gap, without affecting the continuity of the forging process. It can increase die life by 50%–100%, reduce the coefficient of friction from 0.4–0.6 to 0.1–0.2, reduce deformation resistance by 15%–25%, reduce forging passes, and increase material utilization by 5%–10%. Compared with traditional spraying, material utilization increases from 40%–60% to over 85%. The equipment has good compatibility and can be integrated with existing vacuum isothermal forging equipment via standard flanges, requiring no large-scale modifications and resulting in low modification costs.

[0042] While the previous solution addressed the core issues of online directional deposition in a vacuum environment, the high cost of process gases and the complexity of equipment remain problems. Therefore, this embodiment proposes the following design for the process gases: While the previous solution addressed the issue of online directional core deposition in a vacuum environment, the problem of improper selection of the high-voltage electrostatic field voltage leading to discharge risk or insufficient charging efficiency still exists. This embodiment addresses this by designing the high-voltage electrostatic field parameters as follows: The high-voltage electrostatic field uses negative high voltage. Negative high voltage has a higher spark discharge breakdown threshold and better discharge stability than positive high voltage.

[0043] The voltage range is -8 to -3kV. This range represents the optimal range for balancing discharge safety and charging efficiency.

[0044] The control unit automatically adjusts the output voltage of the high-voltage DC power supply based on the real-time air pressure inside the coating chamber. When the air pressure is high, the voltage is appropriately increased to ensure stable corona discharge; when the air pressure is low, the voltage is appropriately decreased to avoid spark discharge.

[0045] While ensuring that the droplets acquire sufficient charge, the risk of vacuum gap spark discharge is effectively reduced, thereby improving the safety and stability of system operation.

[0046] While the previous solution addressed the core issues of online directional deposition in a vacuum environment, the problem of mismatch between directional deposition time and production cycle time still exists. This embodiment addresses this by designing the directional deposition time as follows: The time for a single directional deposition is 10-60 seconds. The duration is determined based on the mold surface area and cavity complexity.

[0047] This ensures sufficient deposition on the die surface while adapting to the forging production cycle. The forging interval is typically 60-120 seconds, and the deposition time falls entirely within this window.

[0048] For simple planar molds, the deposition time is set to 10-20 seconds; for medium-complexity cavity molds, the deposition time is set to 20-40 seconds; and for complex deep cavity molds, the deposition time is set to 40-60 seconds.

[0049] While ensuring sufficient deposition of glass lubricant on the mold surface, it is fully compatible with the existing production cycle of vacuum isothermal forging, without occupying additional production time, thus improving equipment utilization. For multi-pass continuous forging processes, production efficiency can be increased by 20% to 30%.

[0050] While the previous solution addressed the core issues of online directional deposition under vacuum conditions, the challenge of balancing liquid supply accuracy and refueling convenience under high vacuum remains. This embodiment addresses this by designing the liquid supply system as follows: Methods for supplying glass lubricant slurry to an ultrasonic atomizing nozzle include: The glass lubricant slurry is stored in a sealed tank. Optionally, the sealed tank is a stainless steel pressure vessel capable of withstanding alternating changes in vacuum and atmospheric pressure.

[0051] The sealed storage tank is connected to the coating chamber via a vacuum pipeline. Optionally, the vacuum pipeline is a metal bellows. The vacuum pipeline connection achieves the first stage of pressure balance, eliminating the huge pressure difference between atmospheric pressure and vacuum, and fundamentally preventing uncontrollable inflow of slurry due to pressure difference.

[0052] This ensures that the pressure inside the sealed storage tank is consistent with the pressure inside the coating chamber. The first-stage pressure balance makes the pressures in the sealed storage tank and the coating chamber equal, eliminating the pressure difference driving force between the liquid supply system and the coating chamber. The slurry flows only under the active drive of the liquid supply device.

[0053] A transition chamber is provided between the outlet of the sealed storage tank and the ultrasonic atomizing nozzle. The transition chamber is a buffer chamber used to eliminate pressure fluctuations caused by factors such as changes in the liquid level of the sealed storage tank, and to provide stable inlet pressure conditions for the liquid supply device.

[0054] A differential pressure relief valve maintains a pressure difference of 1000~5000Pa between the transition chamber and the ultrasonic atomizing nozzle. Optionally, the differential pressure relief valve is a vacuum-specific control valve. The sealed storage tank, transition chamber, differential pressure relief valve, and liquid supply device are all located on the atmospheric side outside the vacuum chamber. The valve body of the differential pressure relief valve operates in the atmospheric environment. Its reference pressure end senses the vacuum pressure inside the coating chamber in real time through a pressure-sensing pipeline. Using the vacuum pressure as a reference, it stably maintains the pressure in the transition chamber at a slightly positive pressure level 1000~5000Pa higher than the coating chamber pressure, achieving a second-stage pressure balance. This architecture ensures that the mechanical structure of the differential pressure relief valve operates normally in the atmospheric environment, avoiding the risk of failure of the valve diaphragm and spring assembly due to the vacuum environment.

[0055] The liquid supply device supplies liquid to the ultrasonic atomizing nozzle at a set flow rate. Optionally, the liquid supply device is a micro-injection pump, which can precisely control the liquid supply flow rate within the range of 0.01~10mL / min.

[0056] A dual-redundant isolation valve is installed between the sealed storage tank and the coating chamber. Optionally, the dual-redundant isolation valve consists of two electromagnetic vacuum valves connected in series.

[0057] Used to cut off the gas supply between the sealed storage tank and the coating chamber during refueling. By sequentially closing two isolation valves, a dual gas supply cutoff is achieved, effectively preventing vacuum leakage caused by single valve failure.

[0058] After restoring the sealed storage tank to normal pressure, add material. Fill the sealed storage tank with inert gas until normal pressure is reached, then open the feed port to add slurry.

[0059] Throughout system operation, the sealed storage tank and coating chamber remain connected, with their pressures balanced. The transition chamber maintains a slight positive pressure of 1000-5000 Pa under the control of the differential pressure relief valve. After the liquid supply device is activated, the slurry flows steadily to the ultrasonic atomizing nozzle at a set flow rate. During replenishment, the dual redundant isolation valve is closed, and inert gas is introduced into the sealed storage tank to restore atmospheric pressure before feeding. After feeding is complete, the sealed storage tank is evacuated until the pressure matches that of the coating chamber, and then the isolation valve is opened to restore connectivity.

[0060] This fluid supply system achieves precise metering of glass lubricant slurry in a high-vacuum environment by deploying core components on the atmospheric side and employing a two-stage pressure balancing architecture. Simultaneously, dual redundant isolation valves, combined with an independent replenishment process, enable online replenishment without disrupting the vacuum environment of the coating chamber and forging cavity, ensuring the continuity of the forging process.

[0061] While the previous solution addressed the issue of online directional deposition of the core in a vacuum environment, the problem of uneven deposition thickness on complex curved mold surfaces still exists. This embodiment addresses this by designing the robot's motion control as follows: The robotic arm moves along a preset path. The preset path uses an S-shaped or spiral scanning path.

[0062] The distance between the ultrasonic atomizing nozzle and the mold surface is adjusted in real time according to the curvature of the mold surface. The distance is detected in real time by a laser rangefinder sensor installed at the end of the robotic arm.

[0063] The greater the curvature, the more curved the surface. Curvature refers to the degree of bending of the mold surface; the greater the curvature, the more curved the surface.

[0064] The greater the distance between the ultrasonic atomizing nozzle and the atomizing nozzle, the lower the local electric field intensity, thus preventing excessive deposition.

[0065] The smaller the curvature, the flatter the surface.

[0066] The smaller the distance between the ultrasonic atomizing nozzle and the atomizing nozzle, the better. Reducing the distance increases the local electric field strength and prevents the deposition from becoming too thin.

[0067] The distance should always be maintained within the range of 30~80mm. This range is the effective deposition distance; below 30mm, discharge is likely to occur, and above 80mm, the electric field strength is insufficient.

[0068] This is to compensate for the electric field distortion caused by curvature. Electric field distortion refers to the uneven distribution of electric field intensity caused by different curvatures.

[0069] Maintain a uniform electric field strength. Ensure that the electric field strength at all points on the mold surface is basically the same.

[0070] Ensure consistent deposition thickness.

[0071] During directional deposition, a robotic arm carrying an ultrasonic atomizing nozzle scans the mold surface along a preset path. A laser rangefinder continuously monitors the distance between the nozzle and the mold surface. When an area with high curvature is detected, the robotic arm automatically increases the nozzle distance; when an area with low curvature is detected, the robotic arm automatically decreases the nozzle distance, ensuring that the distance between the nozzle and the mold surface is consistently maintained within the range of 30-80 mm.

[0072] It effectively counteracts the electric field distortion on the surface of complex curved molds, ensuring that the electric field intensity at various points on the mold surface is basically consistent, thus guaranteeing the uniformity of the lubricant layer deposition thickness. The coating uniformity can reach over 90%.

[0073] While the previous solution addressed the core issue of online directional deposition in a vacuum environment, problems still exist regarding loose, easily detached particles after deposition and the safety hazards posed by residual charge. Therefore, this embodiment designs the post-processing steps as follows: After directional deposition is completed. This refers to the period after the ultrasonic generator and liquid supply device are turned off.

[0074] First, keep the electrostatic field energized and let it stand in place for 5-10 seconds. During this standing period, the electrostatic field continues to act on the deposited glass powder particles.

[0075] Then, the residual electrostatic charge is released. The residual electrostatic charge on the electrodes and mold surface is conducted to the ground through a grounding resistor.

[0076] After directional deposition, the high-voltage DC power supply is maintained in output mode for 5-10 seconds. Under the action of the electric field force, the charged glass powder particles further clump together, filling the gaps between the particles. After settling, the high-voltage DC power supply is cut off, and the grounding discharge circuit is connected simultaneously. The mold surface temperature is not lower than 900℃, which can promote the instantaneous softening and sintering of the glass powder, releasing the residual static charge on the electrode and mold surface.

[0077] It improves the density and adhesion of the lubricating film. At the same time, it completely eliminates static electricity safety hazards, ensuring the safe operation of the equipment.

[0078] While the previous solution addressed the core issue of online directional deposition in a vacuum environment, problems still exist, such as thin coatings or even missed coatings at the bottom and rounded corners of complex deep cavity molds. This embodiment employs a layered directional deposition strategy: For complex molds with cavities deeper than 50 mm and minimum corner radii less than 5 mm, there is a significant electric field shielding effect, making uniform coverage impossible with conventional scanning.

[0079] A layered directional deposition strategy was adopted: First, move the ultrasonic atomizing nozzle to the first position. The first position corresponds to above the cavity opening.

[0080] Directional deposition is performed to cover the entire cavity opening. This quickly completes a large-area basic cover of the cavity opening area.

[0081] Next, move the ultrasonic atomizing nozzle to the second position. The second position corresponds to the center of the cavity.

[0082] Localized, targeted deposition is performed on the bottom and sidewalls of the cavity. The local electric field intensity is enhanced, allowing the droplets to penetrate deep into the cavity.

[0083] Finally, move the ultrasonic atomizing nozzle to the third position. The third position corresponds to the area above the rounded corners.

[0084] Localized, targeted deposition is performed on the rounded corner area. The nozzle remains at the rounded corner for several seconds to compensate for the thinner coating caused by electric field shielding.

[0085] After coating begins, the robotic arm first moves the nozzle to the first position, scanning the entire cavity opening to complete the basic coverage. Then, the nozzle descends to the second position to perform a fine scan of the cavity bottom and sidewalls. Finally, the nozzle moves to the third position to perform targeted coating on each rounded corner area. After the three layers are deposited, the robotic arm returns to the standby position.

[0086] It effectively solves the electric field shielding problem of complex deep cavity molds, ensuring sufficient coating thickness at the bottom and rounded corner areas of the cavity, eliminating problems of missed coating and thin coating. The overall coverage of complex cavities reaches over 92%.

[0087] While the previous solution addressed the core issue of online directional deposition in a vacuum environment, the problem of unstable atomization due to variations in the liquid supply flow rate still exists. This embodiment addresses this by designing the atomization mechanism and parameter matching as follows: The ultrasonic atomizing nozzle applies high-frequency ultrasonic mechanical vibrations to the glass lubricant slurry supplied to the atomizing plane. The atomizing plane is the metal plate at the end of the ultrasonic atomizing nozzle.

[0088] This causes capillary waves to form on the surface of the atomized plane. Capillary waves are periodic surface ripples formed by the liquid film under ultrasonic vibration excitation.

[0089] When the vibration amplitude reaches a critical value. The critical amplitude is related to the slurry viscosity and surface tension.

[0090] The liquid film tears at the crest to form droplets. The droplet size is proportional to the capillary wavelength.

[0091] The matching relationship between the slurry flow rate supplied to the atomizing plane and the ultrasonic vibration frequency is adjusted. When the flow rate increases, the vibration frequency is increased accordingly, and when the flow rate decreases, the vibration frequency is decreased accordingly.

[0092] Maintain a stable atomization state within a liquid supply flow rate range of 0.01~10 mL / min. A stable atomization state refers to a stable droplet size distribution and a continuous atomization flow rate without pulsation.

[0093] After the glass lubricant slurry is supplied to the atomizing plane, it forms capillary waves under the action of high-frequency mechanical vibration. When the vibration amplitude reaches a critical value, the liquid film tears at the crest to form micron-sized droplets. The control unit automatically adjusts the ultrasonic vibration frequency according to the set liquid supply flow rate to keep the liquid film thickness within the tearable range.

[0094] Stable ultrasonic atomization was achieved over a wide liquid supply flow range, without dripping or atomization interruptions. The droplet size distribution was uniform, with a uniformity greater than 95%, ensuring the stability of the deposition quality.

[0095] While the previous solution addressed the core issues of online directional deposition in a vacuum environment, problems still exist such as slurry residue clogging the nozzle and the inability to control coating quality in a closed loop. This embodiment adds self-cleaning and closed-loop control functions: A self-cleaning step is automatically performed after directional deposition is completed. The self-cleaning step is automatically triggered after each coating process.

[0096] Inject cleaning solvent at a flow rate of 2-3 times the operating flow rate to rinse the ultrasonic atomizing nozzle and pipeline for 30-120 seconds. The cleaning solvent is anhydrous ethanol or deionized water.

[0097] When an abnormality is detected in the transducer's resonant frequency or impedance, the blockage status is determined by real-time monitoring of the transducer's electrical parameters.

[0098] Trigger pulse cleaning or backflushing. Pulse cleaning refers to injecting cleaning solvent in a high-frequency pulse manner, while backflushing refers to injecting cleaning solvent in the reverse direction from the nozzle outlet.

[0099] After directional deposition is completed. This refers to the completion of residual charge release.

[0100] A laser triangulation sensor was used to measure the height difference on the mold surface before and after directional deposition. The laser triangulation sensor was integrated into the end effector of the robotic arm.

[0101] Obtain the lubricant layer thickness distribution. Calculate the lubricant layer thickness at each point by comparing height maps before and after deposition.

[0102] Ultraviolet fluorescence imaging and machine vision algorithms were used to detect the area covered by the lubricating layer. The ultraviolet fluorescence effect of specific components in the glass powder was utilized.

[0103] Obtain coverage data. Coverage refers to the proportion of the lubricated layer area to the total working surface area of ​​the mold.

[0104] The directional deposition parameters for the next pass are automatically adjusted based on thickness distribution and coverage data. The control unit has a built-in parameter adjustment algorithm that automatically optimizes process parameters based on detection results.

[0105] This includes liquid flow rate, scanning speed, and nozzle height. These parameters are adjusted to compensate for coating quality deviations.

[0106] Achieve closed-loop control to ensure consistent coating quality across each pass.

[0107] After each coating cycle, the three-way valve automatically switches to the cleaning path, flushing the nozzle and piping with a high-flow-rate cleaning solvent. If any transducer parameters are detected as abnormal, pulse cleaning or backflushing is automatically triggered. After coating, a laser triangular displacement sensor scans the mold surface to obtain the thickness distribution, and an ultraviolet fluorescence imaging system captures an image of the covered area. The control unit automatically adjusts the liquid supply flow rate, scanning speed, and nozzle height for the next pass based on the detection results.

[0108] It effectively prevents nozzle clogging caused by residual slurry solidification. It enables real-time detection and closed-loop control of coating quality, ensuring consistent coating quality for each pass and improving the automation level of the production process.

[0109] like Figure 2 As shown in the figure, this specific embodiment also provides a dedicated system for implementing the above-mentioned online directional deposition method for vacuum isothermal forging die lubricant. The following describes this solution from the perspective of system-side logic: This specific embodiment provides an online automatic coating system for mold lubricant in vacuum isothermal forging, including: The coating chamber 200, located inside the vacuum chamber, has an electrically controlled door that can be opened and closed independently to create an internal sealed space. A gas supply system is used to supply process gases into the coating chamber 200 to create a gaseous environment for stabilizing the electrostatic field. A vacuum system is used to perform vacuum treatment inside the coating chamber 200; A guide rail is disposed in the vacuum cavity and its end is connected to the interior of the coating chamber 200. It is configured to guide the lower mold 100 in the vacuum cavity to the coating station in the coating chamber 200. A grounding line is used to connect to the mold located at the coating station inside the coating chamber 200, so that the surface of the mold is grounded. The multi-degree-of-freedom robotic arm 800 has its drive motor 820 and transmission mechanism 830 located outside the vacuum chamber. The transmission mechanism 830 is connected to the end effector 810 located inside the coating chamber 200 through a magnetohydrodynamic sealed drive shaft or a welded bellows sealing structure. An ultrasonic atomizing nozzle 300 is fixed to the end effector 810 and is set inside the coating chamber 200. It is used to atomize glass lubricant slurry into micron-sized droplets by ultrasonic high-frequency vibration. The annular electrode 400, with at least a portion of its edges having a pointed structure, is used to charge the droplet simultaneously through charge induction and corona discharge. The annular electrode 400 is fixed to the end effector 810 and located at the outlet of the ultrasonic atomizing nozzle 300. The annular electrode 400 is configured such that the generated electrostatic field can apply a Coulomb force to the charged droplet to drive the droplet toward the location of the lubricant to be applied within the mold and to deposit it in a directional manner. A high-voltage DC power supply 500 is electrically connected to the annular electrode 400; The sealed storage tank 310 is connected to the coating chamber 200 through a vacuum pipeline, so that the pressure inside the sealed storage tank 310 is consistent with the pressure inside the coating chamber 200. The transition cavity 320 has its inlet connected to the sealed storage tank 310; The injection pump 321 has its inlet connected to the outlet of the transition chamber 320 and its outlet connected to the ultrasonic atomizing nozzle 300. The injection pump 321 is used to draw glass lubricant from the transition chamber 320 and to meter and supply it to the ultrasonic atomizing nozzle 300. Differential pressure relief valve 330, as a pressure relief valve, has its inlet connected to transition chamber 320 and its outlet connected to coating chamber 200. The reference pressure end of differential pressure relief valve 330 is connected to coating chamber 200 through pressure tapping pipeline to maintain the pressure in transition chamber 320 at a level 1000~5000Pa higher than the pressure in coating chamber 200. A dual-redundant isolation valve 340 is installed between the sealed storage tank 310 and the coating chamber 200. It is used to cut off the air passage between the sealed storage tank 310 and the coating chamber 200 when replenishing materials, so that the sealed storage tank 310 can be replenished after returning to normal pressure. The automatic cleaning system selectively connects the liquid supply line to the cleaning solvent storage tank via a three-way valve, which is used to flush the ultrasonic atomizing nozzle 300 and the liquid supply line after the coating operation is completed; it also includes a nozzle blockage diagnosis unit, which determines the blockage status by detecting the transducer resonant frequency or impedance change, and triggers the automatic cleaning system to perform pulse cleaning or backflushing. The control unit 700 is connected to the PLC system of the vacuum isothermal forging equipment. The control unit 700 is configured to automatically start the coating operation during the forging interval and automatically stop and retract the multi-degree-of-freedom robotic arm 800 before the forging action begins. The control unit 700 is also electrically connected to a laser triangulation sensor and an ultraviolet fluorescence imaging sensor. The laser triangulation sensor is integrated into the end effector 810 and is used to detect the thickness distribution of the lubricating layer. The ultraviolet fluorescence imaging sensor is installed on the top of the coating chamber 200 and is used to detect the coverage of the lubricating layer. The control unit 700 is configured to adjust the liquid supply flow rate, scanning speed and nozzle height parameters of the next pass according to the thickness distribution and coverage data under different coating quality conditions.

[0110] In a preferred embodiment, the annular electrode 400 has a double-ring structure, including a first high-voltage annular electrode 400 near the nozzle outlet and a second grounding annular electrode 400 located below it; the distance between the two rings is 10~15mm; wherein, the first high-voltage annular electrode 400 has an inner diameter of 25mm and an outer diameter of 30mm, is made of stainless steel 304 with nickel plating, and has an edge chamfer radius of 0.2~0.5mm; the second grounding annular electrode 400 has an inner diameter of 35mm and an outer diameter of 40mm.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. All such modifications or substitutions should be covered within the protection scope of this application, and should not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for online directional deposition of a mold lubricant in vacuum isothermal forging, characterized in that, Includes the following steps: S1. A coating chamber is set up inside a vacuum isothermal forging furnace; and a robotic arm for providing glass lubricant is set up inside the coating chamber, and an ultrasonic atomizing nozzle for ultrasonic atomization treatment of glass lubricant is assembled on the robotic arm. S2. Maintain the initial environment inside the coating chamber consistent with the environment inside the vacuum isothermal forging furnace. After moving the lower mold of the mold to the grounding position inside the coating chamber, seal the coating chamber. S3. Introduce process gas into the coating chamber to create a process environment that can meet the requirements of a stable high-voltage electrostatic field. S4. After the robotic arm moves and the ultrasonic atomizing nozzle is directed toward the mold and moved to a preset position, the glass lubricant is atomized into micron-sized droplets by ultrasonic high-frequency mechanical vibration. S5. A high-voltage electrostatic field is constructed in the region from the ultrasonic atomizing nozzle to the mold, and the droplets acquire charge based on induced charging and corona charging technology. The high-voltage electrostatic field is configured to apply a Coulomb force to drive the charged droplets to be deposited directionally from the ultrasonic atomizing nozzle to the location of the glass lubricant to be coated in the lower mold. S6. After the glass lubricant is deposited, the coating chamber is evacuated so that the pressure inside the coating chamber is close to the pressure inside the vacuum isothermal forging furnace. S7. Open the coating chamber, remove the lower mold from the coating chamber and return it to the furnace chamber.

2. The method for online directional deposition of a mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, The process gas is argon.

3. The method for online directional deposition of mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, The high-voltage electrostatic field uses a negative high voltage. The voltage range is -8 to -3kV.

4. The method for online directional deposition of a mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, The single directional deposition time is 10~60 seconds to ensure sufficient deposition on the mold surface while adapting to the forging production cycle.

5. The method for online directional deposition of a mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, The method of supplying glass lubricant slurry to the ultrasonic atomizing nozzle includes: The glass lubricant slurry is stored in a sealed tank, which is connected to the coating chamber via a vacuum pipeline, so that the pressure inside the sealed tank is consistent with the pressure inside the coating chamber. A transition cavity is provided between the outlet of the sealed storage tank and the ultrasonic atomizing nozzle, and a differential pressure overflow valve is used to maintain the pressure difference between the transition cavity and the ultrasonic atomizing nozzle at 1000~5000Pa. The liquid supply device supplies liquid to the ultrasonic atomizing nozzle at a set flow rate; A dual-redundant isolation valve is provided between the sealed storage tank and the coating chamber to cut off the air passage between the sealed storage tank and the coating chamber during material replenishment, so that the sealed storage tank can be restored to normal pressure before material is added.

6. The method for online directional deposition of a mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, The robotic arm moves along a preset path and adjusts the distance between the ultrasonic atomizing nozzle and the mold surface in real time according to the curvature of the mold surface: the greater the curvature, the greater the distance of the ultrasonic atomizing nozzle; the smaller the curvature, the smaller the distance of the ultrasonic atomizing nozzle, so that the distance is always maintained within the range of 30~80mm, so as to counteract the electric field distortion caused by curvature, maintain a uniform electric field intensity, and ensure consistent deposition thickness.

7. The method for online directional deposition of a mold lubricant for vacuum isothermal forging according to claim 1, characterized in that, After directional deposition is completed, keep the electrostatic field energized and leave it in place for 5 to 10 seconds; then release the residual charge of the electrostatic field.

8. The method for online directional deposition of a mold lubricant in vacuum isothermal forging according to claim 1, characterized in that, For complex molds with cavities deeper than 50 mm and minimum fillet radii less than 5 mm, a layered directional deposition strategy is adopted: First, the ultrasonic atomizing nozzle is moved to the first position to cover the entire cavity opening for directional deposition; The ultrasonic atomizing nozzle is then moved to a second position to cover the bottom and sidewalls of the cavity for localized, targeted deposition. Finally, the ultrasonic atomizing nozzle is moved to the third position to cover the rounded corner area for localized, targeted deposition.

9. The method for online directional deposition of a mold lubricant for vacuum isothermal forging according to claim 1, characterized in that, The ultrasonic atomizing nozzle applies the high-frequency mechanical vibration of the ultrasonic waves to the glass lubricant slurry supplied to the atomizing plane, causing the slurry to form capillary waves on the surface of the atomizing plane. When the vibration amplitude reaches a critical value, the liquid film tears at the crest to form a droplet; By adjusting the matching relationship between the slurry flow rate supplied to the atomizing plane and the ultrasonic vibration frequency, a stable atomization state is maintained within the liquid supply flow rate range of 0.01~10mL / min.

10. The method for online directional deposition of a mold lubricant for vacuum isothermal forging according to claim 9, characterized in that, After directional deposition is completed, a self-cleaning step is automatically performed, in which cleaning solvent is injected at a flow rate of 2 to 3 times the working flow rate to rinse the ultrasonic atomizing nozzle and pipeline for 30 to 120 seconds; when an abnormality in the transducer resonant frequency or impedance is detected, pulse cleaning or backflushing is triggered. After directional deposition is completed, a laser triangulation sensor is used to measure the height difference on the mold surface before and after directional deposition to obtain the thickness distribution of the lubricating layer. Ultraviolet fluorescence imaging and machine vision algorithms are used to detect the coverage area of ​​the lubricating layer to obtain coverage data. Based on the thickness distribution and coverage data, the parameters of the next directional deposition pass, including the liquid supply flow rate, scanning speed and nozzle height, are automatically adjusted to achieve closed-loop control.

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