A system and method for efficient forming and non-destructive peeling of a dried beancurd sheet film

Abstract

The present application relates to the technical field of food processing, and in particular to a system and method for efficient forming and non-destructive peeling of dried beancurd sheet film. The system is a comprehensive system integrating multi-dimensional perception, multi-physical field cooperation and intelligent decision control. Through precise liquid surface control, heat radiation heating, airflow assisted forming and peeling, and local micro-vibration, the system realizes ultra-high precision stability of soybean milk liquid surface, accurate heat supply, and flexible disintegration of the adhesion force between the film and the liquid surface interface. The present application solves or at least alleviates the problems of poor soybean milk liquid surface stability, uneven heating, and film peeling damage in the prior art. The present application provides a system and method for efficient forming and non-destructive peeling of dried beancurd sheet film, which improves the production efficiency and product quality consistency of dried beancurd sheet film, and reduces production loss and film breakage rate.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically a system and method for efficient forming and non-destructive peeling of dried bean curd film. Background Technology

[0002] Tofu skin (yuba) is a traditional bean product with a long history in Chinese culinary culture. Its unique flavor and high nutritional value have made it a favorite among consumers. However, in the modern food industry, the shift from small-scale workshops to large-scale, automated, and mechanized production is a constant pursuit. In this transformation, the rapid and uniform formation of the tofu skin film, followed by its seamless separation from the liquid surface, is crucial for measuring product quality, improving production efficiency, and reducing overall costs. This continuous pursuit of excellence in these key aspects is also the driving force behind the ongoing upgrading of tofu skin production machinery in the food industry.

[0003] Currently, the production of dried bean curd sticks essentially revolves around how to quickly coagulate soybean milk into a film, and then collect the film as dried bean curd sticks. In existing technologies, solving the problems of high consumption and pollution in production has become an important guiding direction. For example, in a dried bean curd stick production unit (Chinese Patent Publication No. CN114642246B), a carbon dioxide circulation system, along with a hot water supply system, provides a heat source for the boiling tank, forming tank, and drying chamber, achieving cascade utilization and energy recovery, thereby reducing consumption and operating costs. Another corresponding technical solution, in a dried bean curd stick production and forming device under atmospheric pressure steam conditions (Chinese Patent Publication No. CN111449141B), uses a reverse-burning atmospheric pressure superheated steam furnace as the main heat source, providing heat for the bean curd stick forming process while also meeting the heating needs of boiling and drying. Its key lies in seeking the supply and utilization of heat energy. These technical solutions have, to some extent, addressed the need for a stable heat source in the production of dried bean curd sticks, and have also made improvements in energy utilization to varying degrees, achieving the goal of reducing consumption. Their design concepts were reasonable and advanced at the time.

[0004] However, to meet the high demands of the food processing industry for product quality uniformity, production efficiency, and automation, the inherent flaws in the aforementioned technical solutions have gradually become apparent, rendering them inadequate for current production challenges. The reason is simple: existing technical solutions focus on macroscopic heat supply and efficiency, while neglecting the micro-environmental control and dynamic matching at the surface of the soy milk during the formation and separation of the bean curd film. Specifically, in the early stages of film formation, the stability of the liquid surface is a prerequisite for ensuring the uniformity of film thickness and quality. However, the liquid surface is easily disturbed and fluctuates during continuous operations such as adding soy milk, evaporation, and film collection. For example, the aforementioned patent CN114642246B fails to address the precise matching of liquid surface stability; the liquid surface is easily disturbed by external factors, leading to uneven film formation and affecting product consistency. Furthermore, the control of liquid surface stability in patent CN111449141B is not well optimized, and liquid surface fluctuations are also a potential cause of uneven film thickness. This liquid surface fluctuation is not a simple geometric distortion. At a deeper level, it directly changes the evaporation rate of the local area of ​​the liquid-gas interface and the enrichment dynamics of protein molecules at the liquid-gas interface. This affects the microstructure, compactness, and even the physical and mechanical strength of the film, which will manifest as uneven quality in subsequent processing and user use and perception.

[0005] First, the aforementioned heating methods themselves have inherent flaws. For example, the strategy employed in CN114642246B, which uses heat transfer to heat the liquid surface, relies on a bottom heating element. Heat is transferred to the surface through a large volume of soy milk, resulting in high thermal inertia and making it unsuitable for rapid temperature control and adjustment as the soy milk surface temperature rises. When production demands change or influencing factors arise, bottom heating cannot quickly match the rising temperature of the liquid surface, hindering rapid film formation and leading to unstable quality of the tofu skin film. While CN111449141B uses efficient superheated steam heating, steam is a gaseous heat medium, and the forming tank is open, making it difficult to control the uniformity of superheated steam distribution on the tofu skin surface. Steam flow, condensation, and attenuation of heat radiation all contribute to uneven temperatures on the liquid surface, creating hot and cold zones. This results in uneven growth of the tofu skin, inconsistent protein coagulation, and the film quality failing to meet the stringent uniformity requirements of industrial production. Therefore, while pursuing overall high efficiency, the above heating methods have not solved the problem of how to achieve instantaneous heat replenishment for the rise of the liquid surface at the microscopic level. What is needed is instantaneous heat that can heat quickly, heat evenly, and can be dynamically adjusted.

[0006] Furthermore, this application also provides the application of the tofu skin film described in any of the above-mentioned technical solutions in the production of tofu skin cups, and its application in the process of peeling the tofu skin film. In addition, after the tofu skin film is made, there is a huge surface tension separation force between the tofu skin film and the surface of the soy milk inside the tofu skin cup. For the tofu skin film, if it is not fully cured or its strength is insufficient, then the separation force between the tofu skin film and the surface of the soy milk, i.e., the surface tension, is the main destructive force during the peeling process. When using mechanical force to peel the tofu skin film, it is necessary to overcome the peeling resistance of the tofu skin film. The greater the peeling resistance of the tofu skin film, the greater the separation force. The greater the separation force, the easier it is for the tofu skin film to break, stretch, tear, or be damaged. None of the above patent applications describe the details of their mechanical peeling methods. This indicates that the mechanical peeling process faces certain difficulties. The technical problem these applications aim to solve is to provide a tofu skin film that does not damage the tofu skin film, can be automatically and continuously peeled, and is highly efficient. However, mechanical peeling methods suffer from huge stress concentration and uneven force distribution, which are problems that non-destructive peeling cannot solve. This stripping method results in a high defect rate and makes it difficult to achieve automated production and increase production line speed, leading to high production costs and unstable product quality.

[0007] Because existing technical solutions emphasize and take measures to improve the macroscopic energy efficiency of bean curd film, they lack systematic research and measures on the principles behind controlling the thermal effects of the film on the microscopic environment of the soybean milk surface during film formation and peeling, achieving uniform and efficient dynamic heating of the film growth interface, and flexibly breaking down the surface tension adhesion effect between the film and the liquid surface. As a result, the forming efficiency of bean curd film is low, the quality uniformity is poor, and non-destructive peeling is difficult; leading to low production efficiency, unstable product quality, and high labor costs. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art, solve or at least alleviate the technical defects of the prior art such as poor stability of the soybean milk surface, uneven heating and slow response, and easy damage during the film peeling process, and provide a system and method for efficient forming and non-destructive peeling of tofu skin film.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a system for efficient forming and non-destructive peeling of dried bean curd film, comprising: The tofu skin production tank unit is used to hold soy milk and provide the physical space for the formation of the tofu skin film. Soy milk storage and conveying unit, used to store pre-treated soy milk and convey it to the tofu skin production tank unit; A precise liquid level control unit is installed inside the tofu skin production tank unit to monitor and adjust the level of soy milk in real time. A thermal radiation heating unit is located directly above the tofu skin production tank unit, and is used to heat the surface of the soy milk in sections and evenly. An airflow-assisted forming and peeling unit is located below the thermal radiation heating unit and adjacent to the surface of the soybean milk, and is used to assist in film forming and peeling. A local micro-vibration generating unit is located below the film peeling area of ​​the bean curd production tank unit to weaken the surface tension adhesion effect between the film and the soybean milk surface.

[0010] To further realize the present invention, the following technical solutions may be preferred: Preferably, the precise liquid level control unit includes: An array of high-precision capacitive liquid level sensors is uniformly arranged along the length of the bean curd production tank unit to acquire fine height distribution data of the soybean milk surface in real time. An ultrasonic pulse ranging sensor is installed above the tofu skin production tank unit to provide an overall height reference for the liquid level; The micro-flow regulating actuator, consisting of a peristaltic pump or a magnetically coupled gear pump, enables precise replenishment or discharge of soy milk, stabilizing the soy milk level within a preset fluctuation range of ±0.2mm. Furthermore, the liquid level precision control unit also includes a microchannel and a micropump for local microcirculation. The microchannel is located at the bottom or side wall of the bean curd production tank unit, and the micropump drives the soy milk in the microchannel to circulate locally, so as to maintain the protein concentration of the soy milk in the area below the film within a preset range.

[0011] Preferably, the thermal radiation heating unit includes: An array consisting of multiple independent radiant heating modules, each with an independent power regulation module and temperature feedback sensor; Multiple distributed infrared temperature measurement point arrays are used to monitor the two-dimensional temperature distribution on the surface of soybean milk in real time; Based on the real-time temperature distribution data of the soybean milk surface, the power of each radiant heating module is dynamically adjusted to ensure that the temperature uniformity of the soybean milk surface in the film formation area reaches ±0.5℃.

[0012] Preferably, the airflow-assisted molding and peeling unit includes: Multiple slit-type laminar flow nozzle arrays are arranged along the length of the tofu skin production tank unit at a spacing of 30 mm, with each nozzle having a slit width of 0.5 mm. A compressed air source is used to supply compressed air to the nozzle array; Multiple proportional flow control valves can independently adjust the airflow pressure and flow rate of each nozzle; During the film formation stage, the nozzle array blows dry air at a preset angle to the liquid surface at a speed of 0.5 m / s to 2 m / s. During the film peeling stage, it adjusts its blowing angle and airflow speed to generate an upward lifting force or a thrust along the direction of film movement.

[0013] Preferably, the local micro-vibration generating unit includes a transducer array, a high-frequency signal generator, and a multi-channel power amplifier; The transducer array is installed on the bottom outer wall of the tofu skin production tank unit or directly submerged below the surface of the soy milk, and is deployed at a spacing of 5mm to 10mm. The operating frequency range of each transducer is 20kHz to 2MHz, and its vibration amplitude and phase can be controlled independently. By controlling the excitation timing, frequency, amplitude, and phase of each transducer, a locally focused acoustic field is formed in the edge region where the film is about to be peeled off, generating a microscale cavitation effect and reducing the effective surface tension of the area where the film contacts the liquid surface.

[0014] A method for efficient forming and non-destructive peeling of dried bean curd film includes the following steps: S1: Precise management of soy milk level. Soy milk is delivered to the tofu skin production tank unit through the soy milk storage and delivery unit. The sensor in the precise liquid level control unit monitors the liquid level height in real time and controls the micro-flow adjustment actuator to stabilize the soy milk level height within a preset fluctuation range of ±0.2mm. The soy milk is also driven to undergo local micro-circulation under the film to maintain the protein concentration within a preset range. S2: Thin film formation and non-destructive peeling, including: S201: Precise thermal radiation and airflow coordination in the film formation stage. The thermal radiation heating unit provides top heating of the soybean milk surface in sections with independent power adjustment. The airflow-assisted forming and peeling unit blows dry air at a preset angle and speed onto the liquid surface to accelerate moisture evaporation and ensure that the bean curd film grows uniformly at the optimal rate. S202: Airflow and micro-vibration assist non-destructive peeling during the film peeling stage. When the thickness of the bean curd film reaches the preset value, the airflow-assisted forming and peeling unit and the local micro-vibration generating unit are controlled to generate an upward gentle lifting airflow or thrust, and the local micro-vibration generating unit is activated to form a local focused sound field in the edge area of ​​the film, dynamically weakening the surface tension adhesion effect between the film and the surface of the soy milk, and realizing non-contact preliminary separation between the bean curd film and the surface of the soy milk.

[0015] Preferably, in step S1, the precise management of the soybean milk level specifically includes: The array of high-precision capacitive liquid level sensors and ultrasonic pulse ranging sensors in the liquid level precision control unit monitor the three-dimensional height distribution data of the soybean milk liquid level in the bean curd production tank unit in real time. After collecting the sensor data, the liquid level height change trend is predicted by using a Kalman filter-based liquid level height prediction algorithm combined with an evaporation rate model. Based on the predicted results and the preset optimal film-forming liquid level, an adaptive PID control strategy is used to control the start, stop, and flow rate of the micro-flow regulation actuator, stabilizing the soybean milk liquid level within a fluctuation range of ±0.2 mm from the preset optimal film-forming height; and The micropump in the liquid level precision control unit drives the soy milk to circulate locally at a flow rate of 80 ml / min along the microchannel in the soy milk area below the formed film, with a directional, low-shear force, in order to maintain the protein concentration of the soy milk in the area below the film within a preset range of 4.5% ± 0.1%.

[0016] Preferably, in step S201, the precise thermal radiation and airflow coordination during the thin film formation stage specifically includes: Multiple far-infrared ceramic radiation heating modules in the thermal radiation heating unit are activated to heat the surface of the soy milk in sections, ensuring that the surface temperature of the film formation area is uniform and maintained between 65°C and 85°C. The array of multiple precision slit-type laminar flow nozzles in the airflow-assisted molding and peeling unit is activated to blow dry air with a preset angle of 5° to 15° and a speed of 0.5m / s to 2m / s onto the surface of the soy milk. The micro-airflow sweeps across the liquid surface in a laminar flow form with a Reynolds number of less than 2000, carrying away water vapor and accelerating the evaporation of moisture. The system continuously monitors the liquid surface temperature, airflow parameters, and humidity sensor data inside the tofu skin production tank unit. Through the dynamic prediction and optimization module, it adjusts the radiation power of the thermal radiation heating module and the airflow pressure, flow rate, and direction of the nozzle array in real time to ensure that the tofu skin film grows uniformly at a thickness growth rate of 0.5 mm to 1.5 mm per minute.

[0017] Preferably, in step S202, the airflow and micro-vibration assisted non-destructive peeling in the film peeling stage specifically includes: The precision slit laminar flow nozzle array in the airflow-assisted forming and peeling unit adjusts its airflow parameters to generate an upward lifting airflow or a thrust along the film collection direction, wherein the airflow velocity is controlled between 0.1 m / s and 0.5 m / s. Activating the transducer array of the local micro-vibration generating unit transmits minute acoustic energy to the surface of the soybean milk beneath the membrane through high-frequency, low-amplitude vibrations at frequencies from 20 kHz to 2 MHz and amplitudes from 0.5 μm to 5 μm; and By controlling the excitation timing, frequency, amplitude, and phase of the transducer, a locally focused acoustic field is formed on the contact line between the film and the liquid surface, inducing a microscale cavitation effect, thereby dynamically weakening the surface tension adhesion effect between the film and the soybean milk surface and reducing the peeling resistance.

[0018] Preferably, the method further includes step S203: system linkage and optimization, continuously monitoring real-time data from all key parameters such as the liquid level sensor group, the infrared thermal imager, the airflow sensor, and the micro-vibration generation and control unit; Achieving highly automated, interconnected control of all sub-steps in S1 and S2, including dynamic adjustment of soybean milk supply flow rate, thermal radiation heating power, airflow intensity, direction, and micro-vibration parameters; and Based on film quality feedback data and energy consumption data, the control model and parameters are adjusted and optimized online to adapt to different production conditions, ensuring the continuous high efficiency of the tofu skin film production process and the consistency of product quality.

[0019] The beneficial effects of this invention are: The system and method provided by this invention achieve precise control of the microenvironment at the surface of soybean milk, including ultra-high precision liquid surface stability, dynamic heat supply down to the regional level, and active intervention in the adhesion force between the film and the liquid surface. This fundamentally solves problems such as liquid surface fluctuation, uneven heating, and peeling damage existing in the prior art. The method significantly improves the forming efficiency of the bean curd sheet by synergistically combining thermal radiation, precise airflow, and local micro-vibration. Furthermore, it achieves non-contact, flexible separation during peeling, greatly reducing the film breakage rate and improving product yield and quality uniformity. The system's high degree of automation and adaptability ensures the stability and optimization of the production process, providing an advanced technical solution for the industrial production of bean curd sheets. Attached Figure Description

[0020] Figure 1 A schematic block diagram of the system structure of the present invention.

[0021] Figure 2 A schematic block diagram of the structure of the dried bean curd production tank unit and related connecting units of the present invention.

[0022] Figure 3 A schematic block diagram of the structure of the dried bean curd production tank unit of the present invention.

[0023] Figure 4 A schematic block diagram of the thermal radiation heating unit and the airflow-assisted forming and peeling unit of the present invention.

[0024] Figure 5A schematic block diagram of the structure of the local micro-vibration generating unit of the present invention.

[0025] Figure 6 A schematic diagram of the synergistic effect of airflow and micro-vibration during the peeling stage of the dried bean curd film of the present invention.

[0026] Figure 7 A schematic flowchart of the method of the present invention. Detailed Implementation

[0027] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0029] This embodiment discloses a system for efficient forming and non-destructive peeling of dried bean curd film. Its overall architecture operates collaboratively to achieve stable and efficient production and flexible, non-destructive peeling of the bean curd film. The core components of this system include a soy milk storage and conveying unit, a bean curd production tank unit, a liquid level precision control unit, a thermal radiation heating unit, an airflow-assisted forming and peeling unit, a local micro-vibration generation unit, and a central intelligent control unit.

[0030] Specifically, the soy milk storage and conveying unit is located at the inlet end of the tofu skin production tank unit, and its main function is to accurately store and convey pre-treated soy milk. This unit consists of two 100-liter food-grade 316L stainless steel soy milk storage tanks equipped with level sensors, each with a built-in high-precision ultrasonic level sensor. Soy milk conveying is achieved by three parallel-running stepper motors driving a precision peristaltic pump. The precision peristaltic pump is connected to the inlet of the tofu skin production tank unit via a corrosion-resistant, high-temperature-resistant food-grade silicone hose, ensuring that the soy milk is not contaminated during conveying. The start-up, stop, and flow rate adjustment of the peristaltic pump are all precisely controlled by the central intelligent control unit based on real-time feedback data from the liquid level precision control unit.

[0031] The tofu skin production tank unit, serving as the core physical space for tofu skin film formation, is manufactured in one piece using food-grade 316L stainless steel. Its overall dimensions are 2000mm long, 500mm wide, and 300mm high. The tank contains four independent slurry-receiving chambers, each rectangular in shape, measuring 450mm long, 200mm wide, and 150mm deep, spaced 20mm apart. The bottom and sidewalls of the slurry-receiving chambers undergo electrolytic polishing and passivation treatment to significantly reduce surface energy and minimize non-specific protein adsorption on the walls, thereby preventing unnecessary adhesion between the film and the tank walls during the forming process. The tank also integrates an internal guide rail structure to assist in film peeling and collection. This guide rail is made of PTFE (polytetrafluoroethylene) material, exhibiting extremely low friction and non-adhesion. Its V-shaped design guides the film to move smoothly towards the collection end.

[0032] Furthermore, the precise liquid level control unit works in conjunction with the soy milk storage and conveying unit to achieve ultra-high precision control of the soy milk level within the tofu skin production tank unit. The core components of this unit are an array of high-precision capacitive liquid level sensors and two ultrasonic pulse ranging sensors. The capacitive liquid level sensor array consists of 15 sensors evenly spaced at 20mm intervals along the length of each soy milk receiving chamber, used to acquire detailed height distribution data of the liquid level in real time, ensuring accurate perception of localized liquid level fluctuations. The ultrasonic pulse ranging sensors are positioned 250mm above the tofu skin production tank unit, providing an overall height reference for the liquid level. All sensor data is transmitted in real time to the central intelligent control unit via a high-speed data acquisition card. The micro-flow regulation actuator consists of the aforementioned precision peristaltic pump. Driven by the central intelligent control unit, it uses an adaptive PID control algorithm to accurately replenish or discharge soybean milk at the milliliter level based on real-time feedback data from the liquid level sensor group and the ultrasonic pulse ranging sensor. This stabilizes the soybean milk level within a preset optimal film-forming height fluctuation range of ±0.2mm, effectively suppressing liquid level drops caused by evaporation and film formation, as well as liquid level fluctuations caused by external disturbances.

[0033] Preferably, the liquid level precision control unit further includes microchannels and a micropump for local microcirculation. The microchannels are integrated into the bottom of the tofu skin production tank unit and are distributed in a grid pattern below the film formation area. The micropump is a low-shear magnetic pump that drives the soy milk in the microchannels to circulate locally, thereby maintaining the protein concentration of the soy milk below the film within a preset range of ±0.5%, preventing uneven film structure caused by excessively rapid local protein consumption.

[0034] The thermal radiation heating unit is positioned 100mm directly above the tofu skin production tank unit to provide zoned and uniform heating of the soy milk surface. This unit consists of an array of 20 independent far-infrared ceramic radiation heating modules, each with an effective radiation area of ​​100mm x 100mm, arranged with a center-to-center distance of 50mm, covering the entire film-forming area. Each radiation heating module is equipped with an independent power drive circuit and power adjustment module, enabling stepless power adjustment between 0W and 1000W. A type K thermocouple is located beneath each module to collect the module's surface temperature. Above the modules, below the heating area, is a non-contact infrared thermal imager to capture the two-dimensional temperature distribution of the soy milk surface and convert the image into precise temperature data, which is then transmitted to the central intelligent control unit. The central intelligent control unit receives the image data from the infrared thermal imager and uses a built-in adaptive PID or fuzzy logic algorithm to drive the power of each radiation heating module, maintaining the temperature of the soy milk surface in the film-forming area within ±0.5℃. Typically, the temperature range is 65℃-85℃.

[0035] The airflow-assisted forming and peeling unit is located below the thermal radiation heating unit, 20mm-50mm above the surface of the soy milk. It consists of 20 slit-type laminar flow nozzles, each with a slit width of 0.5mm and a slit length of 200mm. A nozzle is installed every 30mm along the length of the tofu skin production tank unit. The nozzle array is connected to an oil-free compressed air source via a pipe. The compressed air is filtered by a high-efficiency air filter and then passes through a precision pressure-reducing valve assembly to stabilize the pressure within the range of 0.1MPa-0.5MPa. Each nozzle's outlet is equipped with a proportional flow control valve, independently connected to the nozzle and controlled by a central intelligent control unit, used to individually adjust the airflow pressure and flow rate of each nozzle, thereby controlling the airflow speed and direction. During film formation, the nozzles spray dry air at a velocity of 0.8-1.5ms upwards at a 10° angle to the liquid surface, forming a uniform laminar flow air curtain, which is beneficial for the diffusion and evaporation of water vapor. During the film peeling stage, the nozzle can adjust the blowing angle to 30° and reduce its airflow velocity to 0.1m / s to 0.5m / s through its independent adjustment capability, thereby generating a gentle upward lifting force under the film or a weak thrust in the direction of film movement to assist in the initial separation of the film.

[0036] The localized micro-vibration generating unit is positioned below the film peeling area of ​​the tofu skin production tank unit. It effectively reduces the surface tension adhesion effect between the film and the soy milk surface through a non-contact method before or during film peeling. This unit consists of an array of high-frequency piezoelectric ceramic transducers, mounted on the bottom outer wall of the tofu skin production tank unit, achieving efficient acoustic coupling with the soy milk surface via the stainless steel tank. The transducer array is deployed with a center-to-center distance of 5 mm, each transducer having a diameter of 10 mm and an adjustable operating frequency range from 20 kHz to 2 MHz. Its vibration amplitude and phase can be independently controlled. A high-frequency signal generator produces a square wave or sine wave drive signal with adjustable frequency and amplitude, which drives the transducer array via a 32-channel power amplifier. The central intelligent control unit controls the excitation time, frequency (e.g., 50 kHz or 200 kHz), amplitude (e.g., 0.5 μm to 5 μm), and phase of each transducer in the array, creating a locally focused sound field at the edge where the film is about to be peeled off. This local acoustic field induces microscale cavitation effects, generating and rapidly collapsing microbubbles or producing local acoustic flow, thereby dynamically and flexibly reducing the effective surface tension of the film-liquid contact area, providing an opportunity for subsequent mechanical stripping.

[0037] The central intelligent control unit is responsible for the acquisition, processing, decision-making, control, and optimization of sensor information from all subunits, and has the following software modules: Multi-sensor information fusion module: Receives information from liquid level sensor, temperature sensor, airflow sensor, humidity sensor and micro-vibration generator, uses extended Kalman filter algorithm to fuse heterogeneous multi-source information, remove noise, and establish physical models of important physical parameters such as soybean milk liquid level height, temperature distribution, protein concentration gradient, and film growth. The fused information is used for decision-making, reducing the uncertainty of subsequent information sources to 50%.

[0038] Dynamic Prediction and Optimization Module: Based on historical production data and fused data, this module utilizes deep learning to establish a Long Short-Term Memory (LSTM) network. This network describes the nonlinear relationships between the growth rate, thickness, and protein distribution of the bean curd film and 15 sets of production parameters, including liquid surface temperature, ambient humidity, airflow parameters, and soy milk protein concentration. This model is then used to dynamically predict the growth status within the next 5 minutes, achieving a prediction accuracy of 95%. Building upon this predictive model, a model predictive control method is employed to optimize the global parameters of four types of multi-physics fields: the radiation power of the thermal radiation heating unit, the airflow parameters of the airflow-assisted forming and peeling unit, the soy milk replenishment flow rate of the soy milk storage and transportation unit, and the micro-vibration parameters of the local micro-vibration generation unit. The optimization objectives include maximizing forming speed, achieving optimal thickness uniformity, ensuring high peeling integrity, and minimizing energy consumption, thus achieving the overall optimal balance between production efficiency and product quality.

[0039] Multi-physics field coordinated control module: This module, based on instructions from the dynamic prediction and optimization module, controls the timing, region, and intensity of the thermal radiation heating unit, the airflow-assisted forming and peeling unit, and the local micro-vibration generation unit, achieving coordinated control of each physical field. In the early stages of film growth, the synergistic effect of thermal radiation and airflow is preferentially used to accelerate film growth; once the film has grown to a preset thickness, the module precisely switches to the synergistic effect of airflow-assisted and micro-vibration to peel off the protein fibers, achieving non-destructive separation. The module can achieve nanosecond-level time synchronization, enabling precise coordination and switching of the multi-physics field effects.

[0040] Adaptive and Self-Learning Module: This module tracks actual results during the production process, such as film thickness uniformity (standard deviation), peel integrity rate, and real-time energy consumption from online quality checks. Using reinforcement learning algorithms (e.g., Q-learning or Deep Q-Networks), it learns online and adjusts model parameters based on given specifications (e.g., target standard deviation for film thickness uniformity less than 5%, peel integrity rate greater than 98%). This module identifies and corrects production process deviations caused by factors such as batch-specific soy milk characteristics (e.g., protein content fluctuation ±1%), temperature levels (e.g., room temperature fluctuation ±2°C), humidity levels, and equipment wear, ensuring long-term stable operation and optimal performance. It adjusts production parameters to optimal levels within 2 hours.

[0041] Furthermore, the tofu skin processing conveying mechanism also includes a flexible collection mechanism. This flexible collection mechanism is located at the peeling end of the film in the tofu skin production tank unit and is used to receive and transfer the peeled film. The flexible collection mechanism includes a conveyor belt, two sets of flexible robotic arms disposed on both sides of the conveyor belt, and a set of vacuum suction cups disposed above the conveyor belt. The conveyor belt can be driven to convey the peeled film located thereon. The speed of the conveyor belt can be set to 0.05m / s-0.2m / s. The flexible robotic arms are driven by a pneumatic motor, and silicone suction cups are disposed at the ends of the flexible robotic arms to pick up the edges of the peeled film. The vacuum suction cups include 10 vacuum suction cups with a radius of 10mm. After the peeled film is completely peeled off, the vacuum suction cups support the peeled film to prevent it from being stretched, torn, or contaminated during collection. After collection, the peeled film can be smoothly transported to subsequent drying or cutting processes via the conveyor belt. Example 2

[0042] This embodiment discloses a method for efficient forming and non-destructive peeling of dried bean curd film. The method is implemented through the system and includes the following core steps.

[0043] Step S1: Precise management of the soy milk surface.

[0044] Step S101: Soymilk Delivery and Liquid Level Stabilization. In this step, pre-treated soymilk is continuously or intermittently delivered from the soymilk storage tank to the tofu skin production tank unit via the soymilk storage and delivery unit. The protein content of the pre-treated soymilk is 4.0% to 5.0%, and the temperature is maintained at 90℃ to 95℃. The array of high-precision capacitive level sensors and ultrasonic pulse ranging sensors in the liquid level precision control unit monitor the three-dimensional height distribution data of the soymilk level in the tofu skin production tank unit in real time. After receiving the sensor data, the central intelligent control unit uses a Kalman filter-based liquid level prediction algorithm, combined with a coupled model established by the evaporation rate model and the thin film formation rate model, to predict the liquid level change trend with a delay of less than 5 seconds. Based on the prediction result and the preset optimal film-forming liquid level height (e.g., 10mm below the upper edge of the tank), the central intelligent control unit uses an adaptive PID control strategy to precisely control the start, stop, and flow rate of the micro-flow regulation actuator, achieving dynamic replenishment or discharge of the soymilk level. This control process keeps the level of the soybean milk liquid within a preset range of ±0.2mm fluctuation for several hours, thereby ensuring the stability of the liquid level during the film formation process and avoiding uneven film thickness caused by liquid level fluctuations.

[0045] Step S102: Local Microcirculation of Soy Milk. With the liquid surface stabilized, the microchannels and micropumps in the liquid surface precision control unit are activated. The micropumps drive the soy milk at a flow rate of 80 ml / min to directionally circulate at low shear force in the soy milk area below the formed film along the microchannels. This local microcirculation removes the soy milk below the film whose protein concentration has increased due to water evaporation and protein coagulation (e.g., from an initial 4.5% to 5.5%), and mixes it with soy milk from other areas of the tank while simultaneously replenishing it with fresh soy milk. This process effectively maintains the protein concentration of the soy milk in the area below the film within a preset range of 4.5% ± 0.1%, ensuring uniform protein coagulation throughout the forming process, thereby forming a dense and uniformly thick tofu skin film. The shear force of the circulation flow rate is designed to be less than 0.1 Pa to avoid disturbing the forming film.

[0046] Step S2: Film formation and non-destructive peeling.

[0047] Step S201: Precise Coordination of Thermal Radiation and Airflow in the Thin Film Formation Stage. Once the soybean milk surface is stable, the central intelligent control unit instructs multiple far-infrared ceramic radiation heating modules in the thermal radiation heating unit to activate. These modules heat the soybean milk surface in zones, with the heating power of each zone dynamically controlled by feedback signals from the infrared thermal imager, ensuring that the surface temperature of the formed thin film is uniformly and precisely controlled at 75℃±0.5℃. The thermal radiation power density is typically controlled between 5kW / m² and 10kW / m². The central intelligent control unit then instructs the activation of multiple precision slit-type laminar flow nozzle arrays in the airflow-assisted forming and peeling unit. These nozzle arrays blow dry air at a speed of 1.2m / s, a temperature of 25℃, and a relative humidity of 40% onto the soybean milk surface at a 10° angle to the surface. The micro-airflow, in a laminar flow form with a Reynolds number less than 2000, sweeps across the liquid surface to carry away water vapor generated by accelerated evaporation due to thermal radiation, thus avoiding the formation of a saturated boundary layer above the liquid surface and maximizing the water evaporation rate. Under this synergistic effect, the water evaporation rate can reach 0.8 g / min / m². The central intelligent control unit continuously monitors the liquid surface temperature, airflow parameters (including flow rate and humidity), and humidity sensor data inside the tofu skin production tank unit. Through the dynamic prediction and optimization module, it adjusts the radiation power of the thermal radiation heating module and the airflow pressure, flow rate, and direction of the nozzle array in real time. This precise control ensures that the tofu skin film grows uniformly at an optimal rate (e.g., a thickness growth rate of 0.8 mm to 1.2 mm per minute) and reaches a preset thickness of 0.15 mm to 0.25 mm within 20 minutes, while maintaining the density of its microstructure and avoiding voids or delamination.

[0048] Step S202: Airflow and micro-vibration assisted non-destructive peeling during the film peeling stage. When the thickness of the bean curd film reaches a preset value (e.g., 0.2 mm) and its mechanical strength meets the peeling requirements, the central intelligent control unit instructs the thermal radiation heating unit to enter standby mode, reducing its power to below 100W. At this time, the central intelligent control unit coordinates the airflow-assisted forming and peeling unit and the local micro-vibration generating unit to initiate the film peeling process. The precision slit-type laminar flow nozzle array in the airflow-assisted forming and peeling unit adjusts its airflow parameters to generate a gentle upward lifting airflow perpendicular to the film forming direction, with the airflow velocity precisely controlled at 0.2 m / s, providing initial mechanical separation force. Simultaneously, the local micro-vibration generating unit is activated. Its high-frequency piezoelectric ceramic transducer array, deployed on the bottom outer wall of the bean curd production tank unit and located in the film edge peeling area, transmits minute acoustic energy to the surface of the soybean milk below the film through high-frequency, low-amplitude vibration at a frequency of 50 kHz and an amplitude of 3 μm. The central intelligent control unit precisely controls the excitation timing, frequency, amplitude, and phase of the transducer to form a locally focused sound field with a width of 5 mm at the contact line between the film and the liquid surface, inducing microscale cavitation effects (generating microbubbles with a diameter of approximately 100 micrometers) or local acoustic flow. This effect dynamically weakens the surface tension adhesion between the film and the soy milk surface, reducing the peeling resistance by 30% to 50%. The lifting force generated by the airflow, together with the micro-vibration, achieves a non-contact, smooth initial separation between the tofu skin film and the soy milk surface, significantly reducing the risk of film breakage, stretching, or deformation in the initial peeling stage. The average separation force in the initial peeling stage is reduced by 45%. The peeled film is received and processed non-destructively by the flexible collection mechanism, where a flexible robotic arm gently grasps the edge of the film at a speed of 5 mm / s and smoothly places it on a low surface energy conveyor belt, which transports it to the next process at a speed of 0.1 m / s.

[0049] Step S203: System Linkage and Optimization. The central intelligent control unit continuously monitors real-time data from all key parameters, including the liquid level sensor group, the infrared thermal imager, the airflow sensor, and the micro-vibration generation and control unit. The data stream is updated at a frequency of 100Hz. The central intelligent control unit utilizes the multi-sensor data fusion module, the dynamic prediction and optimization module, and the multi-physics field collaborative control module to achieve highly automated linkage control of all sub-steps in S1 and S2, including dynamic adjustment of soybean milk replenishment flow rate (1 to 5 liters per hour), thermal radiation heating power (100W to 1000W per module), airflow intensity (0.1m / s to 2m / s), direction, and micro-vibration parameters (frequency 20kHz to 2MHz, amplitude 0.5μm to 5μm). The central intelligent control unit further utilizes the adaptive and self-learning module to adaptively adjust and optimize the control model and parameters online based on film quality feedback data (e.g., thickness deviation, color uniformity, protein content distribution) and energy consumption data from downstream online quality inspection units (not shown). This adapts to factors such as the characteristics of different batches of soy milk, changes in environmental conditions, and equipment wear, ensuring the continuous efficiency of the tofu skin film production process and the consistency of product quality. For example, when an increase in film thickness deviation is detected, the system automatically fine-tunes the thermal radiation power and airflow speed to restore the deviation to the normal range within 30 minutes.

[0050] This invention demonstrates superior performance in production indicators such as soybean milk surface height, surface temperature uniformity, film formation rate, film thickness uniformity, and peeling integrity rate. Furthermore, through multi-dimensional sensing, multi-physical field synergy, and centralized control of the production system by a central intelligent control unit, it significantly improves production efficiency, reduces energy consumption, and substantially improves the uniformity of tofu skin film quality. It solves many technical challenges and achieves advanced and reliable industrial production of tofu skin.

[0051] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A system for efficient forming and non-destructive peeling of dried bean curd film, characterized in that, include: The tofu skin production tank unit is used to hold soy milk and provide the physical space for the formation of the tofu skin film. Soy milk storage and conveying unit, used to store pre-treated soy milk and convey it to the tofu skin production tank unit; A precise liquid level control unit is installed inside the tofu skin production tank unit to monitor and adjust the level of soy milk in real time. A thermal radiation heating unit is located directly above the tofu skin production tank unit, and is used to heat the surface of the soy milk in sections and evenly. An airflow-assisted forming and peeling unit is located below the thermal radiation heating unit and adjacent to the surface of the soybean milk, and is used to assist in film forming and peeling. A local micro-vibration generating unit is located below the film peeling area of ​​the bean curd production tank unit to weaken the surface tension adhesion effect between the film and the soybean milk surface. The precise liquid level control unit includes: An array of high-precision capacitive liquid level sensors is uniformly arranged along the length of the bean curd production tank unit to acquire fine height distribution data of the soybean milk surface in real time. An ultrasonic pulse ranging sensor is installed above the tofu skin production tank unit to provide an overall height reference for the liquid level; The micro-flow regulating actuator, consisting of a peristaltic pump or a magnetically coupled gear pump, enables precise replenishment or discharge of soy milk, stabilizing the soy milk level within a preset fluctuation range of ±0.2mm. In addition, the liquid level precision control unit also includes a microchannel and a micropump for local microcirculation. The microchannel is disposed at the bottom or side wall of the bean curd production tank unit, and the micropump drives the soy milk in the microchannel to circulate locally in order to maintain the protein concentration of the soy milk in the area below the film within a preset range. The airflow-assisted forming and peeling unit includes: Multiple slit-type laminar flow nozzle arrays are arranged along the length of the tofu skin production tank unit at a spacing of 30 mm, with each nozzle having a slit width of 0.5 mm. A compressed air source is used to supply compressed air to the nozzle array; Multiple proportional flow control valves can independently adjust the airflow pressure and flow rate of each nozzle; During the film formation stage, the nozzle array blows dry air at a preset angle to the liquid surface at a speed of 0.5 m / s to 2 m / s, and during the film peeling stage, it adjusts its blowing angle and airflow speed to generate an upward lifting force or a thrust along the direction of film movement. The local micro-vibration generating unit includes a transducer array, a high-frequency signal generator, and a multi-channel power amplifier; The transducer array is installed on the bottom outer wall of the tofu skin production tank unit or directly submerged below the surface of the soy milk, and is deployed at a spacing of 5mm to 10mm. The operating frequency range of each transducer is 20kHz to 2MHz, and its vibration amplitude and phase can be controlled independently. By controlling the excitation timing, frequency, amplitude, and phase of each transducer, a locally focused acoustic field is formed in the edge region where the film is about to be peeled off, generating a microscale cavitation effect and reducing the effective surface tension of the area where the film contacts the liquid surface.

2. The system according to claim 1, characterized in that, The thermal radiation heating unit includes: An array consisting of multiple independent radiant heating modules, each with an independent power regulation module and temperature feedback sensor; Multiple distributed infrared temperature measurement point arrays are used to monitor the two-dimensional temperature distribution on the surface of soybean milk in real time; Based on the real-time temperature distribution data of the soybean milk surface, the power of each radiant heating module is dynamically adjusted to ensure that the temperature uniformity of the soybean milk surface in the film formation area reaches ±0.5℃.

3. A method for efficient forming and non-destructive peeling of dried bean curd film, the method being applicable to the system described in claim 2, characterized in that, Includes the following steps: S1: Precise management of soy milk level. Soy milk is delivered to the tofu skin production tank unit through the soy milk storage and delivery unit. The sensor in the precise liquid level control unit monitors the liquid level height in real time and controls the micro-flow adjustment actuator to stabilize the soy milk level height within a preset fluctuation range of ±0.2mm. The soy milk is also driven to undergo local micro-circulation under the film to maintain the protein concentration within a preset range. S2: Thin film formation and non-destructive peeling, including: S201: Precise thermal radiation and airflow coordination in the film formation stage. The thermal radiation heating unit provides top heating of the soybean milk surface in sections with independent power adjustment. The airflow-assisted forming and peeling unit blows dry air at a preset angle and speed onto the liquid surface to accelerate moisture evaporation and ensure that the bean curd film grows uniformly at the optimal rate. S202: Airflow and micro-vibration assist non-destructive peeling during the film peeling stage. When the thickness of the bean curd film reaches the preset value, the airflow-assisted forming and peeling unit and the local micro-vibration generating unit are controlled to generate an upward gentle lifting airflow or thrust, and the local micro-vibration generating unit is activated to form a local focused sound field in the edge area of ​​the film, dynamically weakening the surface tension adhesion effect between the film and the surface of the soy milk, and realizing non-contact preliminary separation between the bean curd film and the surface of the soy milk.

4. The method according to claim 3, characterized in that, In step S1, the precise management of the soybean milk level specifically includes: The array of high-precision capacitive liquid level sensors and ultrasonic pulse ranging sensors in the liquid level precision control unit monitor the three-dimensional height distribution data of the soybean milk liquid level in the bean curd production tank unit in real time. After collecting the sensor data, the liquid level height change trend is predicted by using a Kalman filter-based liquid level height prediction algorithm combined with an evaporation rate model. Based on the preset optimal film-forming liquid level, an adaptive PID control strategy is used to control the start, stop, and flow rate of the micro-flow regulating actuator, stabilizing the soybean milk liquid level within a fluctuation range of ±0.2mm from the preset optimal film-forming height; and The micropump in the liquid level precision control unit drives the soy milk to circulate locally at a flow rate of 80 ml / min along the microchannel in the soy milk area below the formed film, with a directional, low-shear force, in order to maintain the protein concentration of the soy milk in the area below the film within a preset range of 4.5% ± 0.1%.

5. The method according to claim 3, characterized in that, In step S202, the airflow and micro-vibration assisted non-destructive peeling in the film peeling stage specifically includes: The precision slit laminar flow nozzle array in the airflow-assisted forming and peeling unit adjusts its airflow parameters to generate an upward lifting airflow or a thrust along the film collection direction, wherein the airflow velocity is controlled between 0.1 m / s and 0.5 m / s. Activating the transducer array of the local micro-vibration generating unit transmits minute acoustic energy to the surface of the soybean milk beneath the membrane through high-frequency, low-amplitude vibrations at frequencies from 20 kHz to 2 MHz and amplitudes from 0.5 μm to 5 μm; and By controlling the excitation timing, frequency, amplitude, and phase of the transducer, a locally focused acoustic field is formed on the contact line between the film and the liquid surface, inducing a microscale cavitation effect, thereby dynamically weakening the surface tension adhesion effect between the film and the soybean milk surface and reducing the peeling resistance.

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