Leather white ink digital pyrography printing machine control system

Abstract

The present application relates to the technical field of industrial control, in particular to a kind of leather white ink digital pyrograph printing machine control system, including data acquisition module, the two-dimensional space distribution data of the physical attribute of controlled object is obtained;Based on two-dimensional space distribution data, predictive state model is established, and the predictive state variable of controlled object is obtained when the first process acts;Based on the predictive state variable, the first dynamic target value of adjusting the first process parameter is generated;Based on two-dimensional space distribution data, the second target value of adjusting the second process parameter is generated;First control output module is used to output control instruction to equipment first actuator according to the first dynamic target value, adjusts the first process parameter;Second control output module is used to output control instruction to equipment second actuator system according to the second target value to adjust the second process parameter, to enhance leather white ink digital pyrograph printing machine forms dynamic adaptation and collaborative compensation control.

Description

Technical Field

[0001] This invention relates to the field of industrial control technology, specifically to a control system for a digital heat transfer printing machine for leather with white ink. Background Technology

[0002] Digital heat transfer printing is an important process in modern textile printing, but existing control systems lack an effective circulation mechanism to maintain the uniformity and flowability of the ink. Secondly, the process has extremely strict temperature control requirements; different products require precise temperature profile control, but existing systems lack sufficient temperature control accuracy, making it difficult to achieve coordinated temperature control across multiple areas, easily leading to poor results or material damage. Furthermore, existing control systems also have deficiencies in pressure control. The stability and uniformity of the pressure rollers directly affect the quality of pattern transfer, but traditional motor control methods have slow response speeds and low control accuracy. Simultaneously, tension control of the special film is also a key technical challenge; excessive tension can cause film tearing, while insufficient tension can create wrinkles, affecting printing accuracy. In existing technologies, each control subsystem often operates independently, lacking an effective coordinated control mechanism, and cannot adaptively adjust according to different process parameters and material characteristics, resulting in complex equipment operation, low production efficiency, and unstable product quality.

[0003] Therefore, a control system for a digital heat transfer printing machine for leather with white ink is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a control system for a digital heat transfer printing machine for leather with white ink, comprising: a data acquisition module for acquiring two-dimensional spatial distribution data of the physical properties of the controlled object; establishing a predictive state model based on the two-dimensional spatial distribution data to obtain predicted state variables of the controlled object during a first process; generating a first dynamic target value for adjusting the parameters of the first process based on the predicted state variables; generating a second target value for adjusting the parameters of the second process based on the two-dimensional spatial distribution data; a first control output module for outputting control commands to a first actuator of the device according to the first dynamic target value to adjust the first process parameters; and a second control output module for outputting control commands to a second actuator system of the device according to the second target value to adjust the second process parameters, thereby enhancing the dynamic adaptation and collaborative compensation control of the digital heat transfer printing machine for leather with white ink.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A control system for a digital heat transfer printing machine for leather with white ink includes: a data acquisition module for acquiring two-dimensional spatial distribution data of the physical properties of the controlled object;

[0007] The adjustment parameter acquisition module establishes a predictive state model based on two-dimensional spatial distribution data to obtain the predicted state variables of the controlled object during the first process; based on the predicted state variables, it generates a first dynamic target value for adjusting the parameters of the first process; and based on the two-dimensional spatial distribution data, it generates a second target value for adjusting the parameters of the second process.

[0008] The first control output module is used to output control commands to the first actuator of the device according to the first dynamic target value, and adjust the first process parameters;

[0009] The second control output module is used to output control commands to the second actuator system of the device to adjust the second process parameters according to the second target value.

[0010] Preferably, the controlled object is leather; the two-dimensional spatial distribution data includes a leather defect distribution map, correlation curves, and leather types;

[0011] The data acquisition module includes:

[0012] The leather feature recognition unit detects the texture features and physical parameters of the leather surface, identifies scars, pore distribution and color differences on the leather surface, and generates a leather defect distribution map;

[0013] The moisture content gradient detection unit detects the moisture content distribution in different areas of the leather and establishes a correlation curve between moisture content and heat shrinkage rate.

[0014] The automatic leather type identification unit automatically identifies leather types based on texture features and physical parameters.

[0015] Preferably, the white ink circulation control module adjusts the parameters of the white ink circulation based on the leather surface characteristics in the two-dimensional spatial distribution data; when the leather surface texture depth is detected to be greater than a preset texture threshold, the white ink circulation frequency and pressure are increased; when a flat area is detected, the circulation intensity is reduced.

[0016] The white ink concentration monitoring unit monitors the particle dispersion of white ink in real time. When particle aggregation is detected to be greater than the particle aggregation threshold, the enhanced cycle mode is activated.

[0017] Preferably, the first process is a leather tension control process; the second process is a leather thermosetting process.

[0018] The predictive state model includes:

[0019] The leather thermal strain prediction unit, based on two-dimensional spatial distribution data and combined with the shrinkage characteristics of leather collagen fibers, predicts the shrinkage strain and stress distribution of leather during the heating process.

[0020] The strain timing prediction unit predicts the timing and duration of strain occurrence based on the heating temperature curve and the physical properties of the leather.

[0021] The local stress concentration identification unit identifies areas of leather mutation and predicts stress concentration phenomena that will occur in these areas during heat treatment.

[0022] Preferably, the first dynamic target value includes:

[0023] Based on the predicted shrinkage strain and stress distribution, a tension adjustment command is generated before the leather enters the heating zone; specifically, based on the cooling shrinkage characteristics of the leather after leaving the heating zone, combined with the time point and duration of strain occurrence, a segmented tension recovery curve is obtained.

[0024] Based on the stress concentration phenomenon obtained, tension transition control is set in the leather abrupt change area.

[0025] Preferably, the second target value includes:

[0026] The temperature compensation parameters are configured by acquiring thickness, density, and moisture content distribution data of the leather surface through a leather feature recognition unit. The leather surface is divided into multiple calculation units according to a preset grid size. The physical parameters of each calculation unit are analyzed, and when the thickness difference exceeds a thickness threshold and / or the density difference exceeds a density threshold, the area is marked as a sudden change area. The calculation units are grouped into thick areas, thin areas, high-density areas, low-density areas, and sudden change areas. The temperature compensation value of each area is calculated based on the distribution of the leather's physical characteristics. Thicker areas are heated earlier and / or the heating time is extended, while thinner areas are heated less and / or the heating time is shortened.

[0027] The heat penetration depth control parameter adjusts the power output mode of the heater based on the leather density information, so that heat can penetrate leather areas of different densities evenly.

[0028] Temperature gradient control parameters are set to control the temperature gradient in areas of leather mutation.

[0029] Preferably, the temperature gradient control setting process includes:

[0030] The system acquires coordinate information and physical parameter difference data of the mutation boundary through a leather mutation region identification unit; calculates the ideal temperature transition curve at the mutation boundary based on the heat conduction equation and leather thermophysical parameters; discretizes the ideal temperature transition curve into multiple control nodes, each corresponding to the temperature setpoint of a heating unit; calculates the timing trigger time of each control node according to the leather conveying speed and the spatial distribution of the heating units; monitors the actual temperature output of each heating unit in real time through a temperature feedback control system, and activates a temperature compensation mechanism when the deviation between the actual temperature and the set temperature exceeds a set threshold; the temperature compensation mechanism adjusts the power output of adjacent heating units according to the direction and magnitude of the deviation to ensure a smooth transition of the temperature gradient in the leather mutation region.

[0031] Preferably, the powder application control module adjusts the vibration frequency and powder application amount of the powder application device according to the leather surface characteristics in the two-dimensional spatial distribution data; it increases the powder application amount and extends the vibration time for concave areas of the leather surface, and reduces the powder application amount for convex areas of the leather surface.

[0032] The residual powder recovery optimization unit adjusts the suction distribution of the residual powder collection device according to the texture distribution of the leather surface, and regulates the suction in areas where the texture changes.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention introduces "two-dimensional spatial distribution data" and a "predictive state model" to identify the physical properties of the leather surface in different areas, and dynamically adjusts several key process parameters during the printing process accordingly. For areas with obvious scars or abrupt texture changes, fine-tuning of the process can be achieved through tension pre-adjustment, delayed heat treatment, and enhanced white ink circulation to avoid pattern deformation or color difference problems. In areas with smooth surfaces, energy consumption and ink density are automatically reduced, thereby improving printing efficiency and reducing material waste. By implementing a fusion strategy of "local precise response" and "overall collaborative control," this system significantly enhances the adaptability and intelligence level of the leather white ink digital heat transfer printing machine.

[0035] 2. This invention adds a white ink circulation control module and a powder application control module, and adjusts parameters based on the two-dimensional spatial characteristic data of leather. The automatic texture depth recognition function determines the microscopic undulations of the leather surface, and accordingly sets the white ink circulation frequency, pressure, and particle dispersion monitoring strategy to prevent inkjet clogging and uneven deposition. Simultaneously, the powder application amount and vibration frequency are adjusted according to the surface unevenness, increasing the powder application amount and extending the application time in areas with deeper textures, while reducing powder coverage in raised areas.

[0036] 3. This invention integrates four core process units—white ink printing, powder coating, thermal curing, and tension control—for coordinated control. Through the integrated deployment of a "multi-process coordinated optimization control unit" and a "process parameter coupling analysis unit," dynamic balance and response optimization are achieved in complex physical processes. Based on predictive identification of abrupt change regions, the system can automatically determine the response sensitivity of these regions in each process and adjust the corresponding tension control, heating curve, inkjet intensity, and powder coating strategy, forming a dynamic adaptation and coordinated compensation mechanism. Attached Figure Description

[0037] Figure 1 This invention provides a schematic diagram of the control system structure for a digital heat transfer printing machine for leather with white ink.

[0038] Figure 2 A schematic diagram of the control process of the digital heat transfer printing machine for white ink on leather provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the tension adjustment command acquisition process provided in an embodiment of the present invention. Detailed Implementation

[0040] 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.

[0041] Example 1:

[0042] This invention provides a control system for a digital heat transfer printing machine for leather with white ink, as detailed below. Figure 1 The technical solution is as follows:

[0043] It is used in equipment for pattern processing of continuous flexible products; the specific process is as follows: Figure 2 ,include.

[0044] The data acquisition module is used to acquire two-dimensional spatial distribution data of the physical properties of the controlled object;

[0045] The adjustment parameter acquisition module establishes a predictive state model based on two-dimensional spatial distribution data to obtain the predicted state variables of the controlled object during the first process; based on the predicted state variables, it generates a first dynamic target value for adjusting the parameters of the first process; and based on the two-dimensional spatial distribution data, it generates a second target value for adjusting the parameters of the second process.

[0046] The first control output module is used to output control commands to the first actuator of the device according to the first dynamic target value, and adjust the first process parameters;

[0047] The second control output module is used to output control commands to the second actuator system of the device to adjust the second process parameters according to the second target value.

[0048] The controlled object is leather; the two-dimensional spatial distribution data includes a leather defect distribution map, correlation curves, and leather types.

[0049] The data acquisition module includes:

[0050] The leather feature recognition unit detects the texture features and physical parameters of the leather surface, identifies scars, pore distribution and color differences on the leather surface, and generates a leather defect distribution map;

[0051] The moisture content gradient detection unit detects the moisture content distribution in different areas of the leather and establishes a correlation curve between moisture content and heat shrinkage rate.

[0052] The automatic leather type identification unit automatically identifies leather types based on texture features and physical parameters.

[0053] In this embodiment, by accurately identifying leather defects, moisture content distribution, and leather type, the control of multiple parameters during leather processing is achieved. By dynamically optimizing the processing strategy according to the actual state of the leather, the consistency of processing and the quality of finished products are improved.

[0054] Furthermore, the white ink circulation control module adjusts the parameters of the white ink circulation based on the leather surface characteristics in the two-dimensional spatial distribution data; when the leather surface texture depth is detected to be greater than the preset texture threshold, the white ink circulation frequency and pressure are increased; when a flat area is detected, the circulation intensity is reduced.

[0055] The white ink concentration monitoring unit monitors the particle dispersion of white ink in real time. When particle aggregation is detected to be greater than the particle aggregation threshold, the enhanced cycle mode is activated.

[0056] In this embodiment, the white ink circulation parameters are dynamically adjusted according to the characteristics of the leather surface to achieve differentiated processing of different texture areas, thereby improving the uniformity of white ink adhesion on complex surfaces. At the same time, by monitoring the white ink concentration in real time, the problem of ink clogging caused by particle aggregation is avoided, ensuring stable printing quality.

[0057] The first process is the leather tension control process; the second process is the leather thermosetting process.

[0058] The predictive state model includes:

[0059] The leather thermal strain prediction unit, based on two-dimensional spatial distribution data and combined with the shrinkage characteristics of leather collagen fibers, predicts the shrinkage strain and stress distribution of leather during the heating process.

[0060] The strain timing prediction unit predicts the timing and duration of strain occurrence based on the heating temperature curve and the physical properties of the leather.

[0061] The local stress concentration identification unit identifies areas of leather mutation and predicts stress concentration phenomena that will occur in these areas during heat treatment.

[0062] In this embodiment, by constructing a predictive state model that covers the leather tension control and thermosetting process, the shrinkage strain and stress distribution of the leather during the heating process can be predicted in advance, thus avoiding deformation and damage caused by uneven fiber shrinkage during heat treatment.

[0063] The process for obtaining the shrinkage strain and stress distribution of the leather thermal strain prediction unit includes:

[0064] Infrared thermal imaging technology is used to scan the leather surface to obtain leather thickness and density distribution data. Based on the database of thermal shrinkage coefficients of leather collagen fibers and combined with the leather type identification results, the basic shrinkage parameters of the corresponding leather are queried. The thickness distribution data and the basic shrinkage parameters are convolved to generate a shrinkage strain distribution matrix for each region. The shrinkage strain distribution matrix is ​​converted into stress distribution data through finite element analysis. The strain time-series prediction unit establishes a mapping relationship between heating temperature and time, and calculates the time node when each region reaches the critical shrinkage temperature by combining the leather's thermal conductivity coefficient. Based on the leather thickness and moisture content distribution, the strain duration is predicted. The local stress concentration identification unit identifies the abrupt boundary of leather thickness, density, and moisture content through a gradient algorithm, calculates the difference in physical parameters at the abrupt boundary, and predicts the stress concentration coefficient and distribution range based on the principles of materials mechanics.

[0065] By integrating infrared thermal imaging with the thermal shrinkage coefficient of collagen fibers, the thickness, density, and basic shrinkage characteristics of different regions of leather are obtained. Convolution operations and finite element analysis are used to model the shrinkage strain and stress distribution, effectively improving stress control during heat treatment. Through a heating temperature-time mapping model, combined with thermal conductivity and moisture content distribution, accurate prediction of strain time points and duration is achieved, enhancing the controllability of the thermosetting process.

[0066] The first dynamic target value includes:

[0067] Based on the predicted shrinkage strain and stress distribution, tension adjustment instructions are generated before the leather enters the heating zone;

[0068] Based on the cooling and shrinkage characteristics of leather after it leaves the heating zone, and combined with the time point and duration of strain occurrence, a segmented tension recovery curve is obtained;

[0069] Based on the stress concentration phenomenon obtained, tension transition control is set in the leather abrupt change area.

[0070] The process of the tension adjustment command is referred to Figure 3 ,include:

[0071] A pre-adjustment zone is set before the leather enters the heating zone. The length of the pre-adjustment zone is determined based on the leather conveying speed and the predicted strain occurrence time. Based on the predicted shrinkage strain distribution matrix, the required pre-compensation tension value for each zone is calculated. The current tension state of the leather is monitored in real time by distributed tension sensors. The difference between the pre-compensation tension value and the current tension value is calculated to generate a tension adjustment command. The tension transition control setting process includes: identifying the boundary coordinates and physical parameter differences of the leather abrupt change zone; setting buffer control sections before and after the abrupt change zone, with the length of the buffer control section dynamically determined based on the degree of abrupt change and the leather conveying speed; and adopting a gradual tension adjustment mode within the buffer control section, with the tension change rate calculated based on the physical parameter differences and the leather tensile strength data to prevent the leather from tearing or deforming in the abrupt change zone.

[0072] By setting a pre-adjustment zone before leather heating, combined with predicted shrinkage strain and stress distribution, tension can be controlled in advance, effectively mitigating the risk of deformation caused by heat-induced strain. A segmented tension recovery curve is employed to match the nonlinear shrinkage characteristics of the leather during cooling, improving the timeliness and stability of tension control. For abrupt change areas, by dynamically identifying differences in physical parameters, a buffer control segment is set and a gradual tension adjustment strategy is implemented to avoid tearing, breakage, or surface deformation caused by stress concentration, significantly improving the continuity of the processing and product yield.

[0073] The second target value includes:

[0074] The temperature compensation parameters are configured by acquiring thickness, density, and moisture content distribution data of the leather surface through a leather feature recognition unit. The leather surface is divided into multiple calculation units according to a preset grid size. The physical parameters of each calculation unit are analyzed, and when the thickness difference exceeds a thickness threshold and / or the density difference exceeds a density threshold, the area is marked as a sudden change area. The calculation units are grouped into thick areas, thin areas, high-density areas, low-density areas, and sudden change areas. The temperature compensation value of each area is calculated based on the distribution of the leather's physical characteristics. Thicker areas are heated earlier and / or the heating time is extended, while thinner areas are heated less and / or the heating time is shortened.

[0075] The heat penetration depth control parameter adjusts the power output mode of the heater based on the leather density information, so that heat can penetrate leather areas of different densities evenly.

[0076] Temperature gradient control parameters are set to control the temperature gradient in areas of leather mutation.

[0077] The process involves scanning the entire leather surface in a grid pattern to obtain thickness measurements for each computational unit. A region is defined as thick if its thickness exceeds 110% of the baseline thickness, and thin if its thickness is less than 80%. Thick regions require longer heat penetration time and higher heating power during heat treatment, so heating is initiated earlier and the heating time is extended. Thin regions, due to their faster heat conduction and greater susceptibility to overheating, are treated with 10% to 20% lower heating power and a shorter heating time to ensure consistent heat treatment results across all regions.

[0078] Density distribution data for different regions of the leather is obtained. Using the standard density value of leather as a benchmark, regions with a density exceeding 115% of the standard density value are classified as high-density regions; regions with a density below 85% of the standard density value are classified as low-density regions. High-density regions, due to their dense fiber structure, have difficulty heat penetration, requiring increased heater power output and extended heat treatment time. Low-density regions, due to their loose fibers, have rapid heat conduction, necessitating a lower-power pulse heating mode to avoid fiber damage caused by localized overheating.

[0079] The process of setting up the temperature gradient control includes:

[0080] The system acquires coordinate information and physical parameter difference data of the mutation boundary through a leather mutation region identification unit; calculates the ideal temperature transition curve at the mutation boundary based on the heat conduction equation and leather thermophysical parameters; discretizes the ideal temperature transition curve into multiple control nodes, each corresponding to the temperature setpoint of a heating unit; calculates the timing trigger time of each control node according to the leather conveying speed and the spatial distribution of the heating units; monitors the actual temperature output of each heating unit in real time through a temperature feedback control system, and activates a temperature compensation mechanism when the actual temperature deviates from the set temperature by more than a set threshold; the temperature compensation mechanism adjusts the power output of adjacent heating units according to the direction and magnitude of the deviation to ensure a smooth transition of the temperature gradient in the leather mutation region and avoid local overheating or uneven heating of the leather caused by temperature mutation.

[0081] By setting zoned temperature compensation parameters, heat penetration depth control parameters, and temperature gradient control parameters, the thermodynamic regulation of different physical properties of the leather is achieved. For areas with significant differences in thickness and density, the heating power and duration are dynamically adjusted to improve the uniformity of heat treatment. Especially in abrupt change areas, by constructing an ideal temperature transition curve and implementing discrete control nodes and a temperature feedback adjustment mechanism, a smooth temperature gradient transition is ensured, effectively avoiding abnormal shrinkage and surface defects caused by local overheating or underheating, and significantly improving the stability and processing quality of the heat treatment process.

[0082] The powder application control module adjusts the vibration frequency and powder application amount of the powder application device according to the leather surface characteristics in the two-dimensional spatial distribution data; it increases the powder application amount and extends the vibration time for concave areas of the leather surface, and reduces the powder application amount for convex areas of the leather surface.

[0083] The residual powder recovery optimization unit adjusts the suction distribution of the residual powder collection device according to the texture distribution of the leather surface, and enhances the suction in areas with deeper texture.

[0084] By dynamically adjusting the amount of powder applied and the vibration frequency according to the unevenness of the leather surface, the powder application can be controlled, improving the uniformity of adhesion. At the same time, the suction distribution of the residual powder removal device can be adjusted according to the depth of the texture to effectively avoid residual powder or insufficient adsorption, thereby improving the clarity of the pattern and the processing quality.

[0085] The multi-process collaborative optimization control unit unifies and coordinates the four process links of white ink printing, powder application, heat curing and tension control; and adjusts the white ink printing parameters, powder application parameters, heating parameters and tension parameters corresponding to the mutation areas of the leather according to the physical characteristics of the mutation areas.

[0086] The process parameter coupling analysis unit analyzes the mutual influence between different process parameters. When adjusting one process parameter, it calculates and adjusts other related process parameters.

[0087] Through multi-process collaborative optimization control, unified adjustment of white ink printing, powder application, thermal curing and tension control is achieved. Multi-parameter linkage optimization is carried out for abrupt change areas to effectively avoid process conflicts and uneven processing. Through process parameter coupling analysis, adaptive adjustment between parameters is achieved to improve overall processing consistency and stability.

[0088] This invention addresses the pattern processing of continuous flexible leather products. By acquiring two-dimensional spatial distribution data of leather defects, moisture content, and type, a predictive state model is constructed to dynamically control multiple process parameters, including tension, thermal curing, white ink printing, and powder coating. The system features infrared thermal imaging, strain prediction, tension pre-adjustment, temperature gradient control, and multi-process collaborative optimization. It can accurately adapt to changes in the physical properties of leather, especially in abrupt regions, achieving multi-parameter linkage compensation and dynamic coordination to avoid problems such as stress concentration, overheating, or uneven powder coating, significantly improving the consistency, yield, and stability of pattern processing. When a process parameter is adjusted (e.g., increasing heating power), the system can automatically analyze its potential impact on other parameters (e.g., tension or white ink concentration) and adjust them in real time, preventing performance degradation due to localized optimization. This intelligent closed-loop adjustment capability not only significantly improves the overall control accuracy and robustness of the system but also provides a technical foundation for personalized, multi-batch leather printing processing.

[0089] Example 2:

[0090] As another embodiment of the present invention, this embodiment is mainly aimed at the precision printing processing scenario of high-end leather products.

[0091] The leather feature recognition unit first uses laser 3D scanning technology to comprehensively inspect the leather surface, accurately identifying microscopic texture changes. The system then analyzes the scanned data using image processing algorithms, automatically marking scar locations, pore density distribution areas, and color change boundaries to generate a leather defect distribution map containing coordinate information. The moisture content gradient detection unit employs near-infrared spectroscopy to establish a gridded detection point network on the leather surface, acquiring real-time moisture content values ​​for each area and establishing a curve showing the correlation between moisture content and expected heat shrinkage rate.

[0092] The system has a built-in standard feature database for various leather types, including texture feature parameters and physical property parameters of common leathers. By comparing the detected texture depth, pore shape, surface hardness and other feature parameters with the standard parameters in the database, the system uses a pattern matching algorithm to automatically identify the type of leather.

[0093] The leather thermal strain prediction unit calculates the expected shrinkage of each region at different heating temperatures based on acquired leather thickness distribution data and collagen fiber thermal shrinkage characteristic parameters of different leather types using numerical analysis methods. The system divides the leather surface into several calculation units, calculating the shrinkage strain and the resulting internal stress distribution for each unit. The strain timing prediction unit analyzes the heater's temperature output curve and the leather's thermal conductivity to predict the time point at which each region reaches the shrinkage initiation temperature, as well as the duration of the shrinkage process, providing a time reference for tension control.

[0094] The system identifies abrupt changes in the physical parameters of the leather surface using a boundary detection algorithm, including the boundaries of abrupt changes in thickness, density, and moisture content. When the difference in physical parameters between adjacent regions exceeds a preset threshold, the system marks that region as an abrupt change area. Based on the principles of materials mechanics, stress concentration occurs at abrupt change boundaries. The system calculates the stress concentration factor using finite element analysis to predict risk areas where cracks or deformation may occur.

[0095] Based on the predicted shrinkage strain distribution data, the tension distribution is adjusted in the pre-conditioning section before the leather enters the heating zone. The length of the pre-conditioning section is determined according to the leather conveying speed and the predicted thermal response time. Differentiated pre-compensation tension is applied to different areas through a multi-point tension control mechanism. The magnitude of the compensation tension is proportional to the predicted shrinkage strain. The segmented tension recovery curve takes into account the nonlinear shrinkage characteristics of the leather during the cooling process, dividing the cooling process into three stages: rapid cooling, stable cooling, and natural cooling. Different tension recovery strategies are adopted in each stage.

[0096] A buffer control section, three to five centimeters in length, is set before and after the identified mutation area. The length of the buffer section is dynamically adjusted according to the degree of mutation. Within the buffer control section, a gradual tension adjustment mode is used, with the tension change rate controlled to no more than 5% per second to avoid damage to the leather from rapid tension changes. The system monitors the stress response of the leather in real time, and automatically reduces the tension change rate or suspends tension adjustment when an abnormal stress peak is detected.

[0097] The zoned temperature compensation parameters are calculated based on the leather thickness and density distribution. For areas with a thickness exceeding the standard, heating is initiated earlier and the heating time is extended. For areas with a thickness less than 20% of the standard thickness, the heating power is reduced by 10% to 20%, and the heating time is shortened accordingly. The heat penetration depth control parameters are based on the leather density information, adjusting the heater's power output mode to ensure that heat can penetrate leather areas of different densities evenly, avoiding the problem of surface overheating and insufficient internal heating.

[0098] The detailed implementation process of temperature gradient control is as follows: First, the precise coordinate information and physical parameter difference data of the abrupt boundary are obtained. Then, the ideal temperature transition curve is calculated based on the heat conduction theory. The temperature transition curve is discretized into multiple control nodes, corresponding to an independent heating unit. The triggering sequence of each control node is calculated according to the leather conveying speed to ensure that the temperature gradient is synchronized with the leather movement. The temperature feedback control system monitors the actual temperature output of each heating unit in real time. When the temperature deviation exceeds ±3 degrees Celsius, the power compensation mechanism of the adjacent heating unit is activated.

[0099] The optimization strategy of the white ink circulation control module is as follows: Based on the detected leather surface texture depth data, the white ink circulation parameters are dynamically adjusted. When the texture depth exceeds 0.5 mm, the system increases the white ink circulation frequency by 20% to 40% and increases the circulation pressure by 10% to 20% to ensure that the white ink can fully penetrate into the texture depth. For areas with high surface flatness, the system reduces the circulation intensity by 10% to 20% to reduce unnecessary energy consumption. The white ink concentration monitoring unit uses the optical scattering principle to monitor the dispersion state of particles in the white ink. When the detected particle aggregation exceeds the set threshold, the enhanced circulation mode is automatically activated, increasing the stirring intensity until the particles are redispersed uniformly.

[0100] The precise adjustment method for powder application control includes: the powder applicator adjusts the vibration frequency and powder application amount according to the unevenness of the leather surface; for areas with surface depressions deeper than 0.3 mm, the system increases the powder application amount by 30% to 50% and extends the vibration time by 20% to 40% to ensure that the powder can fully fill the depression area. For areas with surface protrusions higher than 0.2 mm, the system reduces the powder application amount by 20% to 30% to avoid excessive powder accumulation in the protruding areas. The excess powder recovery optimization unit adjusts the suction distribution according to the texture depth, increasing suction by 20% to 30% in areas with deeper textures to ensure that excess powder is effectively recovered.

[0101] This embodiment achieves intelligent and coordinated control of multiple key parameters in the printing process by establishing a precise detection system for the physical properties of leather. First, two-dimensional spatial distribution data of the leather is acquired through various detection technologies. Then, a predictive state model is established to predict potential physical changes in the leather during processing. Based on the prediction results, the system dynamically adjusts process parameters such as tension control, temperature control, white ink circulation, and powder application to achieve synergistic optimization of each process step. Particularly in areas of abrupt leather change, the system effectively avoids problems such as stress concentration, uneven temperature, and material deformation through a multi-parameter linkage compensation mechanism, significantly improving the consistency and stability of printing quality.

[0102] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A control system for a digital heat transfer printing machine for leather with white ink, characterized in that, include: The data acquisition module is used to acquire two-dimensional spatial distribution data of the physical properties of the controlled object; The adjustment parameter acquisition module establishes a predictive state model based on two-dimensional spatial distribution data to obtain the predicted state variables of the controlled object during the first process. Based on the predicted state variables, a first dynamic target value for adjusting the first process parameters is generated; Based on two-dimensional spatial distribution data, a second target value for adjusting the parameters of the second process is generated; The first process is the leather tension control process; The second process is the thermal curing of the leather. The predictive state model includes: The leather thermal strain prediction unit, based on two-dimensional spatial distribution data and combined with the shrinkage characteristics of leather collagen fibers, predicts the shrinkage strain and stress distribution of leather during the heating process. The strain timing prediction unit predicts the timing and duration of strain occurrence based on the heating temperature curve and the physical properties of the leather. The local stress concentration identification unit identifies areas of leather mutation and predicts stress concentration phenomena that will occur in these areas during heat treatment. The first dynamic target value includes: Based on the predicted shrinkage strain and stress distribution, tension adjustment instructions are generated before the leather enters the heating zone; specifically: Based on the cooling and shrinkage characteristics of leather after it leaves the heating zone, and combined with the time point and duration of strain occurrence, a segmented tension recovery curve is obtained; Based on the stress concentration phenomenon observed, tension transition control is implemented in the leather abrupt change area; The second target value includes: The temperature compensation parameters are configured by acquiring thickness, density, and moisture distribution data of the leather surface through a leather feature recognition unit. The leather surface is divided into multiple calculation units according to a preset grid size. The physical parameters of each calculation unit are analyzed, and when the thickness difference exceeds a thickness threshold and / or the density difference exceeds a density threshold, the area is marked as abrupt change region. The calculation units are grouped into thick regions, thin regions, high-density regions, low-density regions, and abrupt change regions. The temperature compensation value of each region is calculated based on the distribution of leather physical characteristics, and the temperature of abrupt change regions is adjusted in advance. The heat penetration depth control parameter adjusts the power output mode of the heater based on the leather density information, so that heat can penetrate leather areas of different densities evenly. Temperature gradient control parameters: Set temperature gradient control in areas of leather aberration. The first control output module is used to output control commands to the first actuator of the device according to the first dynamic target value, and adjust the first process parameters; The second control output module is used to output control commands to the second actuator of the device according to the second target value, and adjust the second process parameters.

2. The control system for a digital heat transfer printing machine for leather with white ink according to claim 1, characterized in that: The controlled object is leather; the two-dimensional spatial distribution data includes a leather defect distribution map, correlation curves, and leather types. The data acquisition module includes: The leather feature recognition unit detects the texture features and physical parameters of the leather surface, identifies scars, pore distribution and color differences on the leather surface, and generates a leather defect distribution map; The moisture content gradient detection unit detects the moisture content distribution in different areas of the leather and establishes a correlation curve between moisture content and heat shrinkage rate. The automatic leather type identification unit automatically identifies leather types based on texture features and physical parameters.

3. The control system for a digital heat transfer printing machine for leather with white ink according to claim 1, characterized in that, Also includes: The white ink circulation control module adjusts the parameters of the white ink circulation based on the leather surface characteristics in the two-dimensional spatial distribution data. When the texture depth of the leather surface is detected to be greater than the preset texture threshold, the white ink circulation frequency and pressure are increased; when a flat area is detected, the circulation intensity is reduced. The white ink concentration monitoring unit monitors the particle dispersion of white ink in real time. When particle aggregation is detected to be greater than the particle aggregation threshold, the enhanced cycle mode is activated.

4. The control system for a digital heat transfer printing machine for leather with white ink according to claim 1, characterized in that: The process of setting up the temperature gradient control includes: The mutation boundary is obtained through a leather mutation region identification unit; based on the heat conduction equation and leather thermophysical parameters, the ideal temperature transition curve at the mutation boundary is calculated; the ideal temperature transition curve is discretized into multiple control nodes, each corresponding to the temperature setpoint of a heating unit; the timing trigger time of each control node is calculated according to the leather conveying speed and the spatial distribution of the heating units; the actual temperature output of each heating unit is monitored in real time through a temperature feedback control system, and when the deviation between the actual temperature and the set temperature exceeds a set threshold, a temperature compensation mechanism is activated; the temperature compensation mechanism adjusts the power output of adjacent heating units according to the direction and magnitude of the deviation.

5. The control system for a digital heat transfer printing machine for leather with white ink according to claim 1, characterized in that, Also includes: The powder application control module adjusts the vibration frequency and powder application amount of the powder application device according to the leather surface characteristics in the two-dimensional spatial distribution data; it increases the powder application amount and extends the vibration time for concave areas of the leather surface, and reduces the powder application amount for convex areas of the leather surface. The residual powder recovery optimization unit adjusts the suction distribution of the residual powder collection device according to the texture distribution of the leather surface, and regulates the suction in areas where the texture changes.

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