System and method for characterizing adhesion at the workpiece and mold interface in hot die forming

Abstract

The application discloses a system and method for characterizing adhesion between a workpiece and a die in hot die forming, which comprises a hot die forming device and a surface feature observation device. The hot die forming device comprises a temperature controller, a lower die, an upper die, a pressure rod, a force sensor and a temperature sensor. The surface feature observation device is used to detect the distribution form parameters of the adhesion residues and the surface defect parameters after the separation of the workpiece and the upper die. The hot die forming device is used to detect the demolding parameters of the workpiece in the demolding process, and the surface feature observation device is used to detect the surface feature parameters of the workpiece after demolding. The quantitative relationship between the adhesion and the die forming parameters can be established through the demolding parameters and the surface feature parameters, the adhesion between the workpiece and the die in the hot die forming can be quantitatively measured and characterized, and the hot die forming process design is facilitated.

Description

Technical Field

[0001] This invention relates to the field of adhesion characterization technology, and more particularly to a characterization system and method for the adhesion of the workpiece and mold interface in hot molding. Background Technology

[0002] In thermoforming, thermoplastic workpieces and molds undergo plastic deformation under complex stress and temperature conditions. During demolding, adhesion occurs at the workpiece-mold interface, affecting mold life and finished product quality. To address the damage caused by adhesion, quantitatively characterizing interfacial adhesion is paramount. Taking precision glass molding, a typical thermoplastic molding process, as an example, the molding process involves heating, molding, demolding, and cooling. During demolding, interfacial adhesion between the workpiece and mold causes surface damage to the mold and a decline in the surface quality of the molded part. Therefore, suitable adhesion characterization techniques are urgently needed to study the generation and evolution of adhesion, thereby providing insights and a basis for reducing or even completely avoiding interfacial adhesion.

[0003] Currently, the characterization of interfacial release adhesion in the thermoplastic molding process of precision optical components mainly focuses on two aspects: release force measurement and microscopic characterization. On the one hand, release force measurement devices are often limited to specific application scenarios and cannot be well applied to a wide range of thermoplastic molding applications. On the other hand, the characterization of workpiece adhesion on the mold surface is incomplete, and a universal standard for evaluating adhesion cannot be established. These problems all affect the quality control of finished products and the service life of molds in thermoplastic molding processes. Therefore, the existing technology for characterizing adhesion is incomplete and cannot provide quantitative measurement.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a characterization system and method for the adhesion of the workpiece and mold interface in hot molding, in order to address the above-mentioned deficiencies of the prior art. The aim is to solve the problem that the characterization of adhesion in the prior art is not comprehensive and cannot be quantitatively measured.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows:

[0007] A characterization system for the adhesion between a workpiece and a mold interface in hot molding, comprising: a hot molding apparatus and a surface feature observation device;

[0008] The hot molding apparatus includes:

[0009] The thermostat has an internal chamber.

[0010] The lower mold is set in the cavity and forms a placement position for placing the workpiece;

[0011] The upper mold is located inside the cavity;

[0012] A pressure rod is connected to the upper mold and extends out of the cavity;

[0013] A force sensor, connected to the pressure rod, is used to detect the tensile adhesion force value when the workpiece and the upper mold interface separate;

[0014] Temperature sensor for the temperature inside the cavity;

[0015] The surface feature observation device is used to detect the distribution parameters of the adhesive residue after the separation of the workpiece and the upper mold interface, as well as the surface defect parameter α. d .

[0016] The aforementioned system for characterizing the adhesion between the workpiece and the mold interface in hot molding, wherein the surface feature observation device includes at least one of a scanning electron microscope, a 3D profilometer, and an atomic force microscope.

[0017] The aforementioned system for characterizing the adhesion between the workpiece and the mold interface in hot molding, wherein the surface defect parameters include: the percentage difference between roughness and reference roughness; the distribution form parameters include at least one of: scatter distribution parameters, island aggregation parameters, linear flow parameters, and surface coverage parameters accompanied by wrinkles, and each distribution form parameter includes: the distribution size of adhesive residue, the area percentage of adhesive residue, and the distribution morphology of adhesive residue.

[0018] The aforementioned system for characterizing the adhesion between the workpiece and the mold interface in hot molding, wherein the workpiece is a thermoplastic workpiece, and the thermoplastic workpiece includes at least one of glass workpieces, plastic workpieces, and metal workpieces.

[0019] A method for characterizing the adhesion between a workpiece and a mold interface in hot molding, wherein the method is applied to the characterization system for the adhesion between a workpiece and a mold interface in hot molding as described in any of the above claims, and the characterization method includes the following steps:

[0020] Place the workpiece on the lower mold, and then place the upper mold and the lower mold against both sides of the workpiece respectively;

[0021] Inert gas is introduced into the chamber, and the temperature inside the chamber is controlled by a thermostat for heating and insulation.

[0022] The workpiece is molded to obtain the holding time, and the molding pressure value is detected by a force sensor;

[0023] The workpiece is demolded, and the tensile adhesion force value when the workpiece and the upper mold interface are separated is detected by the force sensor, and the temperature value is detected by the temperature sensor.

[0024] Cooling is achieved by controlling the temperature inside the chamber using a thermostat;

[0025] The workpiece is removed, and the distribution parameters of the adhesive residue after the separation of the workpiece and the upper mold interface and the surface defect parameters are detected by the surface feature observation device. The nominal contact area between the workpiece and the mold before demolding is determined.

[0026] Determine the surface energy of the mold, the surface energy of the workpiece, and the interfacial energy between the workpiece and the mold, and determine the adhesive stress value based on the tensile adhesion force value and the nominal contact area between the workpiece and the mold before demolding after deformation.

[0027] A quantitative relationship between the adhesion stress value and the molding parameters is established based on the adhesion stress value, the mold surface energy, the workpiece surface energy, the interface energy between the workpiece and the mold, the nominal contact area between the deformed workpiece and the mold before demolding, the temperature value, the holding time, the molding pressure value, and the surface defect parameters.

[0028] The method for characterizing the adhesion between the workpiece and the mold interface in the hot molding process, wherein the surface energy of the mold is:

[0029]

[0030] Where, γ mold Indicates the surface energy of the mold. This represents the percentage concentration of the i-th type of atom on the mold surface within the overall atomic composition of the mold surface. f represents the surface enthalpy of the i-th atom on the mold surface. i The coefficient representing the degree to which the i-th type of atom on the mold surface is surrounded by vacuum, c0 represents a constant, and V i Let represent the molar volume of the i-th type of atom on the mold surface in its pure state, and n represent the number of types of atoms in the atomic composition of the mold surface;

[0031] The surface energy of the workpiece is:

[0032]

[0033] Where, γ glass Represents the surface energy of the workpiece. This represents the percentage concentration of the j-th atom on the workpiece surface in the atomic composition of the workpiece surface. f represents the surface enthalpy of the j-th atom on the workpiece surface. j V represents the degree to which the j-th atom on the workpiece surface is surrounded by vacuum. j Let m represent the molar volume of the j-th atom on the workpiece surface in its pure state, and m represent the number of atom types in the atomic composition of the workpiece surface.

[0034] The interfacial energy between the workpiece and the mold is:

[0035]

[0036]

[0037]

[0038] Where, γ Interaction This represents the interfacial energy between the workpiece and the mold. It is the interfacial enthalpy value when the i-th type of atom on the mold surface is completely surrounded by the j-th type of atom on the workpiece surface. It is the interfacial enthalpy value when the j-th atom on the workpiece surface is completely surrounded by the i-th atom on the mold surface.

[0039] The method for characterizing the adhesion between the workpiece and the mold interface in the hot molding process, wherein the adhesion stress value is:

[0040]

[0041] Where σ represents the adhesive stress value, F ad Indicates the tensile adhesion force value, A de This represents the nominal contact area between the workpiece and the mold before demolding after deformation.

[0042] The method for characterizing the adhesion between the workpiece and the mold interface in hot molding, wherein the quantitative relationship between the adhesion stress value and the molding parameters is as follows:

[0043]

[0044] W ad =γ mold +γ glass -γ Interaction

[0045]

[0046] Among them, W ad Indicates reference temperature T ref Thermodynamic adhesion work under the given conditions, α d Ra represents the surface defect parameter, and Ra is the surface roughness. ref The roughness is represented by T, the molding temperature by P, the molding pressure by t, and the holding time by T. ref P represents the reference temperature. ref t represents the reference pressure. ref For reference holding time, K is a proportionality coefficient, and a, b, and c all represent coefficients.

[0047] The method for characterizing the adhesion between the workpiece and the mold interface in the hot molding process includes controlling the relative movement of the upper mold and the lower mold during the molding process to make the molding pressure value reach a preset molding force value, and keeping the molding pressure value unchanged during the holding time.

[0048] The method for characterizing the adhesion between the workpiece and the mold interface in hot molding includes, during the demolding process of the workpiece, the displacement value of the upper mold or the lower mold is collected by a displacement collector to keep the moving speed of the upper mold or the lower mold constant.

[0049] Beneficial effects: The hot molding device is used to detect demolding parameters during the demolding process, and the surface feature observation device is used to detect the surface feature parameters of the workpiece after demolding. A quantitative relationship between adhesion and molding parameters can be established through demolding parameters and surface feature parameters. It can quantitatively measure and characterize the adhesion between the workpiece and the mold interface in hot molding, and provide assistance for the design of hot molding process. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the hot molding apparatus in an embodiment of the present invention.

[0051] Figure 2 This is a schematic flowchart of a method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to an embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram illustrating the changes in temperature, force, and displacement over time in each process of the embodiments of the present invention.

[0053] Explanation of reference numerals in the attached figures:

[0054] 1. Upper mold; 2. Force sensor; 3. Lower mold; 4. Chamber; 5. Workpiece; 6. Pressure rod. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0056] Please also refer to Figures 1-2 This invention provides some embodiments of a characterization system for the adhesion of the workpiece and mold interface in hot molding.

[0057] like Figure 1As shown, the system for characterizing the adhesion between the workpiece and the mold interface in hot molding of the present invention includes: a hot molding apparatus and a surface feature observation device. The hot molding apparatus is used to detect demolding parameters during the demolding process, and the surface feature observation device is used to detect surface feature parameters of the workpiece after demolding. Demolding parameters include tensile adhesion force, temperature, holding time, molding pressure, mold surface energy, initial height of the workpiece before demolding, and final height after demolding. Surface feature parameters include the distribution pattern of adhesive residues after demolding and surface defect parameters. The distribution pattern parameters include at least one of scattered distribution parameters, island aggregation parameters, linear flow parameters, and surface coverage parameters accompanied by wrinkles. The adhesive residues after demolding... The adhesive residue will exhibit certain distribution patterns, specifically scattered distribution, island-like aggregation, linear flow distribution, and wrinkled surface coverage distribution. Scattered distribution indicates a star-shaped distribution of adhesive residue on the upper or lower mold; island-like aggregation indicates a discontinuous, blocky aggregation of adhesive residue; linear flow distribution indicates a linear distribution with a clear flow trajectory; and wrinkled surface coverage distribution indicates a large-area coverage of adhesive residue. Parameters for each distribution pattern include: the size of the adhesive residue distribution, the percentage of the adhesive residue area, and the distribution morphology. Surface defect parameters include: the percentage difference between the surface roughness and the reference roughness, i.e., the ratio of the difference between the surface roughness and the reference roughness to the reference roughness. A quantitative relationship between adhesion and molding parameters can be established using demolding parameters and surface feature parameters.

[0058] The hot molding apparatus includes:

[0059] The thermostat has an internal chamber 4;

[0060] The lower mold 3 is set inside the cavity 4 and forms a placement position for placing the workpiece 5;

[0061] Upper mold 1 is located inside the chamber 4;

[0062] The pressure rod 6 is connected to the upper mold 1 and extends to the outside of the chamber 4;

[0063] Force sensor 2 is connected to the pressure rod 6 and is used to detect the tensile adhesion force value when the interface between the workpiece 5 and the upper mold 1 separates;

[0064] Temperature sensor for the temperature inside chamber 4;

[0065] The surface feature observation device is used to detect the distribution parameters of the adhesive residue after the interface between the workpiece 5 and the upper mold 1 is separated, as well as the surface defect parameters.

[0066] Specifically, the temperature controller is used to control the temperature inside the chamber 4. The temperature controller includes a heat insulation cover and a heating device (such as a heating wire). The heating device is located inside the heat insulation cover, which has an opening. The pressure rod 6 is located inside this opening. Both the lower mold 3 and the upper mold 1 are located inside the chamber 4. During the molding process, the upper mold 1 and / or the lower mold 3 can be moved, causing them to move closer together or further apart. This application uses the upper mold 1 to move, controlled by the pressure rod 6. Figure 2 As shown.

[0067] Force sensor 2 is used to detect the tensile adhesion force when the interface between the workpiece 5 and the upper mold 1 separates during the demolding process. Force sensor 2 is also used to detect the molding pressure of the upper mold 1 on the workpiece 5 during the molding process. Temperature sensor is used to detect the temperature inside the chamber 4.

[0068] To make the adhesion between the tested workpiece 5 and the mold interface closer to the adhesion between the workpiece 5 and the mold in actual production or experimentation of hot molding, the materials of the upper mold 1 and the lower mold 3 in the hot molding apparatus are the same as the materials of the molds in actual production or experimentation, and the surface roughness of the upper mold 1 and the lower mold 3 is the same as the surface roughness of the molds in actual production or experimentation. The surface roughness of the workpiece 5 in this application is the same as the surface roughness of the workpiece 5 in actual production or experimentation. The shape of the workpiece 5 in this application can be any suitable shape (e.g., cylindrical), and it can be the same as or different from the shape of the workpiece 5 in actual production or experimentation. During the characterization process, the workpiece 5 needs to undergo operations such as heating, heat preservation, molding, demolding, and cooling. The process parameters of the workpiece 5 in this application in each operation can be the same as or different from the process parameters of the workpiece 5 in each operation in actual production or experimentation.

[0069] In a preferred embodiment of the present invention, the surface feature observation device includes at least one of a scanning electron microscope, a 3D profilometer, and an atomic force microscope.

[0070] Specifically, characterization methods for the features of adherent surfaces include, but are not limited to, multi-scale (macro-micro-nano) observation techniques such as scanning electron microscopy, 3D profilometer, and atomic force microscopy.

[0071] In a preferred embodiment of the present invention, the workpiece 5 is a thermoplastic workpiece, which includes at least one of glass workpieces, plastic workpieces, and metal workpieces.

[0072] Specifically, thermoplastic workpieces can also be composite structures, for example, with a thermoplastic coating formed on the surface, i.e., a coating made of thermoplastic materials.

[0073] This invention addresses the problems of limited methods and complex measurements in existing characterization techniques for the adhesion between workpieces and molds in thermoforming. This invention is a technique for detecting the interfacial adhesion force during the demolding process of workpieces and molds in thermoplastic molding. It simplifies the method for detecting the force value during the interface separation process, establishes a direct link between molding parameters and adhesion, and is applicable to the quantitative characterization of the adhesion between workpieces and molds in a wide range of multi-scale thermoplastic molding processes.

[0074] This method involves real-time monitoring of the tensile adhesion force at the interface between the mold and the workpiece. The adhesion stress is calculated by combining the tensile adhesion force with the nominal contact area. Furthermore, it combines microscopic characterization techniques to achieve quantitative characterization of adhesion. By using force monitoring combined with mechanical control, it enables interface separation regulation under various operating environments, thus achieving quantitative, microscopic, and direct characterization of interface separation adhesion.

[0075] Based on the characterization system for the adhesion between the workpiece and the mold interface in hot molding described in any of the above embodiments, the present invention also provides a preferred embodiment of a method for characterizing the adhesion between the workpiece and the mold interface in hot molding:

[0076] like Figure 2 As shown, the method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to an embodiment of the present invention includes the following steps:

[0077] Step S100: Place the workpiece on the lower mold, and then place the upper mold and the lower mold against both sides of the workpiece.

[0078] Step S200: Inert gas is introduced into the chamber, and the temperature inside the chamber is controlled by a temperature controller to raise and maintain the temperature.

[0079] Step S300: The workpiece is molded to obtain the holding time, and the molding pressure value is detected by a force sensor.

[0080] Step S400: Demold the workpiece, and detect the tensile adhesion force value when the workpiece and the upper mold interface separate using the force sensor, and detect the temperature value using the temperature sensor.

[0081] Step S500: Cooling is achieved by controlling the temperature inside the chamber using a temperature controller.

[0082] Step S600: Take out the workpiece, and use a surface feature observation device to detect the distribution parameters of the adhesive residue after the workpiece and the upper mold interface are separated, as well as the surface defect parameters, and determine the nominal contact area between the workpiece and the mold before demolding after deformation.

[0083] Step S700: Determine the surface energy of the mold, the surface energy of the workpiece, and the interface energy between the mold and the workpiece, and determine the adhesive stress value based on the tensile adhesion force value and the nominal contact area between the workpiece and the mold before demolding after deformation.

[0084] Step S800: Establish a quantitative relationship between the adhesion stress value and the molding parameters based on the adhesion stress value, the mold surface energy, the workpiece surface energy, the interface energy between the workpiece and the mold, the nominal contact area between the deformed workpiece and the mold before demolding, the temperature value, the holding time, the molding pressure value, and the surface defect parameters.

[0085] Specifically, during the hot molding process, the initial height of the workpiece is measured, which refers to the height of the workpiece along the direction of the molding pressure. The workpiece is then placed on the lower mold, and the pressure rod is moved to the upper mold, clamping the workpiece between the upper and lower molds. An inert gas, such as He, Ar, or N2, is introduced into the cavity, and the temperature inside the cavity is adjusted by a temperature controller at an appropriate heating rate (5-8℃ / s). After reaching the specified temperature, the temperature is held for a period of time (600-800s).

[0086] After adjusting the temperature inside the cavity, during the molding process of the workpiece, the upper mold and the lower mold are controlled to move relative to each other so that the molding pressure value reaches the preset molding force value and the molding pressure value is kept constant during the holding time.

[0087] To maintain a constant temperature within the mold chamber, the workpiece is molded. First, the pressure bar is moved downwards at a relatively high speed, applying pressure to the workpiece through the upper mold. Once the pressure sensor detects that the molding pressure has reached the preset molding force value, the pressure is maintained at this preset value for a specified holding time. Since the workpiece deforms under pressure, the pressure bar needs to be moved downwards at a lower speed to compensate for this deformation. Specifically, a displacement sensor can be used to collect the displacement value of the pressure bar, ensuring that the displacement value remains constant per unit time, thus maintaining a constant moving speed. The displacement sensor records the molding pressure and displacement values ​​at an appropriate frequency (e.g., 600Hz).

[0088] During the demolding process of the workpiece, the displacement value of the upper mold or the lower mold is collected by a displacement acquisition device to keep the moving speed of the upper mold or the lower mold (e.g., 1 μm / s) constant.

[0089] During demolding, the upper mold and / or lower mold can be moved. In this application, a pressure rod is used to move the upper mold. The pressure rod moves the upper mold at a fixed speed, causing it to detach from the workpiece. Initially, the force sensor reading rapidly drops to zero, meaning the upper mold applies no pressure to the workpiece. As the pressure rod continues to move, due to interfacial adhesion between the upper and lower molds and the workpiece, the force sensor reading becomes the tensile adhesion force. This tensile adhesion force gradually increases, reaching its maximum value when the tensile adhesion force reaches its maximum value (because the direction of the mold pressure and the tensile adhesion force are opposite). Figure 3 The lowest point of the curve during the demolding process is the maximum value of the tensile adhesion force. As the upper mold gradually detaches from the workpiece interface, the tensile adhesion force gradually decreases until the upper mold completely detaches from the workpiece, at which point the force sensor reading becomes zero. Temperature values ​​are detected by a temperature sensor during the demolding process.

[0090] After demolding, the temperature inside the cavity is controlled by a temperature controller for cooling, with a relatively slow cooling rate. During the cooling process, the pressure bar can be stopped or moved upwards at a slow speed.

[0091] After cooling, the workpiece is removed, and the distribution parameters of the adhesive residue on the surface of the workpiece after demolding and the surface defect parameters are detected by the surface feature observation device. The final height of the molded workpiece is measured, and the nominal contact area between the workpiece and the mold before demolding is determined.

[0092] Based on the initial height and the final height, determine the final deformation of the workpiece. The final deformation is:

[0093]

[0094] Where ε represents the final deformation, l represents the final height, and l0 represents the initial height. The final deformation can be recorded as supplementary data to determine the parameters of the workpiece machining process.

[0095] The nominal contact area between the deformed workpiece and the mold before demolding can be determined based on the distribution parameters, for example, by statistically analyzing the adhesion surface using relevant software.

[0096] The surface energy of the mold and the surface energy of the workpiece are determined based on the material composition characteristics of the mold. Typically, the surface energy is:

[0097]

[0098] Where, γ S Represents surface energy. This represents the percentage concentration of the i-th type of atom in the surface atomic composition. f represents the surface enthalpy of the i-th atom. iThe coefficient represents the degree to which the i-th atom is surrounded by vacuum, c0 represents a constant, and V i Let represent the molar volume of the i-th atom in its pure state, and n represent the number of atom types in the surface atomic composition.

[0099] Specifically, the surface energy of the mold is:

[0100]

[0101] Where, γ mold Indicates the surface energy of the mold. This represents the percentage concentration of the i-th type of atom on the mold surface within the overall atomic composition of the mold surface. f represents the surface enthalpy of the i-th atom on the mold surface. i The coefficient representing the degree to which the i-th type of atom on the mold surface is surrounded by vacuum, c0 represents a constant, and V i Let represent the molar volume of the i-th type of atom on the mold surface in its pure state, and n represent the number of types of atoms in the atomic composition of the mold surface;

[0102] The surface energy of the workpiece is:

[0103]

[0104] Where, γ glass Represents the surface energy of the workpiece. This represents the percentage concentration of the j-th atom on the workpiece surface in the atomic composition of the workpiece surface. f represents the surface enthalpy of the j-th atom on the workpiece surface. j The coefficient representing the degree to which the j-th atom on the workpiece surface is surrounded by vacuum, c0 represents a constant, and V j Let m represent the molar volume of the j-th atom on the workpiece surface in its pure state, and m represent the number of atom types in the atomic composition of the workpiece surface.

[0105] Taking the chemical composition of two elements as an example, the surface energy is:

[0106]

[0107] in, X represents surface energy. m Y n This indicates the atomic composition of the mold surface, with the percentage of atoms X and Y expressed as m:n. This indicates the concentration of atom X in the surface atomic composition. Let f represent the surface enthalpy of atom X, f represent the degree to which surface atoms A and B are surrounded by vacuum (e.g., 0.31 for alloys and amorphous glasses), and c0 represent a constant (e.g., 4.5 × 10⁻⁶). 8 V XThis represents the molar volume of atom X in its pure state. This indicates the concentration of atom Y in the surface atomic composition. V represents the surface enthalpy of atom Y. Y This represents the molar volume of atom Y in its pure state.

[0108] Based on the interfacial contact energy between the mold and the glass, it is necessary to calculate the interaction energy between the material elements on both sides of the interface. The interfacial energy between the workpiece and the mold is:

[0109]

[0110]

[0111]

[0112] Where, γ Interaction This represents the interfacial energy between the workpiece and the mold. It is the interfacial enthalpy value when the i-th type of atom on the mold surface is completely surrounded by the j-th type of atom on the workpiece surface. It is the interfacial enthalpy when the j-th atom on the workpiece surface is completely surrounded by the i-th atom on the mold surface, where c0 represents a constant and γ is the interfacial interaction energy. Interaction The result can be obtained by summing up all possible element-related effects; further proof is not provided here.

[0113] Based on the tensile adhesion force value, the adhesive stress value is determined. The adhesive stress value is:

[0114]

[0115] Where σ represents the adhesive stress value, F ad Indicates the tensile adhesion force value, A de This represents the nominal contact area between the workpiece and the mold before demolding after deformation. The tensile adhesion force value here is the maximum value of the tensile adhesion force.

[0116] By repeatedly adjusting parameters such as temperature, molding pressure, holding time, and gas environment, multiple sets of data can be obtained. Based on these data, a quantitative relationship between adhesion and molding parameters can be established. This helps reduce the impact of interfacial adhesion on the surface quality of the mold and workpiece, thereby enabling the manufacturing of multi-scale (such as nanoscale microarrays) precision thermoplastic components. The method of this invention is applicable to the quantitative characterization of workpiece and mold interfacial adhesion in a wide range of multi-scale thermoplastic molding processes.

[0117] The method for characterizing the adhesion between the workpiece and the mold interface in hot molding is characterized in that the quantitative relationship between the adhesion stress value and the molding parameters is as follows:

[0118]

[0119] W ad =γ mold +γ glass -γ Interaction

[0120]

[0121] Where σ represents the adhesive stress value, A de W represents the nominal contact area between the deformed workpiece and the mold before demolding. ad Indicates reference temperature T ref Thermodynamic adhesion work under the given conditions, α d Ra represents the surface defect parameter, and Ra is the surface roughness. ref The roughness is represented by T, the molding temperature by P, the molding pressure by t, and the holding time by T. ref P represents the reference temperature. ref t represents the reference pressure. ref For reference holding time, K is a proportionality coefficient, a, b, c represent coefficients, and γ mold γ represents the surface energy of the mold. glass γ represents the surface energy of the workpiece. Interaction This represents the interfacial energy between the workpiece and the mold, i.e., the interfacial tension between the workpiece and the mold. Specific Implementation Example 1

[0123] In precision glass molding, interfacial adhesion between the workpiece and the mold occurs during the physical demolding stage. For interfacial separation over a wide temperature range, the interfacial separation force and adhesive stress can directly reflect the adhesion strength during demolding and the influence of the gas environment, temperature, pressure, and coating on interfacial adhesion.

[0124] First, after cleaning, the workpiece is placed on the surface of the lower mold. Ar gas is then introduced into the cavity and maintained for 20 minutes to ensure a stable gas environment throughout the cavity. Next, the heating device within the cavity begins heating at a rate of 1.5°C / s until the entire cavity reaches the specified temperature, which is then maintained for 10 minutes to ensure uniform temperature distribution. Then, the upper mold moves downwards to reach the preset forming force value. This forming force is maintained constant for 3 minutes to allow sufficient stress relaxation time for the workpiece. Afterwards, the mold and workpiece are separated at a moving speed of 1 μm / s. Finally, the entire cavity is cooled to 25°C at a rate of 0.3°C / s to remove the workpiece, which is then characterized using a surface feature observation device.

[0125] Based on the experimental output of tensile adhesion force, mold surface energy, workpiece surface energy, workpiece-mold interfacial energy, nominal contact area between the workpiece and mold before demolding, temperature, holding time, molding pressure, and surface defect parameters, a quantitative relationship between adhesion stress and molding parameters is established. Adhesion force is detected using a force sensor, temperature is recorded using a thermocouple method, and microscopic surface defects are statistically analyzed using a scanning electron microscope and a 3D profilometer.

[0126] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for characterizing the adhesion between a workpiece and a mold interface in hot molding, characterized in that, A characterization system for the adhesion between the workpiece and the mold interface in hot molding, comprising: a hot molding apparatus and a surface feature observation device; The hot molding apparatus includes: The thermostat has an internal chamber. The lower mold is set in the cavity and forms a placement position for placing the workpiece; The upper mold is located inside the cavity; A pressure rod is connected to the upper mold and extends out of the cavity; A force sensor, connected to the pressure rod, is used to detect the tensile adhesion force value when the workpiece and the upper mold interface separate; Temperature sensor for the temperature inside the cavity; The surface feature observation device is used to detect the distribution parameters of the adhesive residue and surface defect parameters after the workpiece and the upper mold interface separate. The surface feature observation device includes at least one of a scanning electron microscope, a 3D profilometer, and an atomic force microscope. The characterization method includes the following steps: Place the workpiece on the lower mold, and then place the upper mold and the lower mold against both sides of the workpiece respectively; Inert gas is introduced into the chamber, and the temperature inside the chamber is controlled by a thermostat for heating and insulation. The workpiece is molded to obtain the holding time, and the molding pressure value is detected by a force sensor; The workpiece is demolded, and the tensile adhesion force value when the workpiece and the upper mold interface are separated is detected by the force sensor, and the temperature value is detected by the temperature sensor. Cooling is achieved by controlling the temperature inside the chamber using a thermostat; The workpiece is removed, and the distribution parameters of the adhesive residue after the separation of the workpiece and the upper mold interface and the surface defect parameters are detected by the surface feature observation device. The nominal contact area between the workpiece and the mold before demolding is determined. Determine the surface energy of the mold, the surface energy of the workpiece, and the interfacial energy between the mold and the workpiece; and determine the adhesive stress value based on the tensile adhesion force value and the nominal contact area between the workpiece and the mold before demolding after deformation. A quantitative relationship between the adhesion stress value and the molding parameters is established based on the adhesion stress value, the mold surface energy, the workpiece surface energy, the interface energy between the workpiece and the mold, the nominal contact area between the deformed workpiece and the mold before demolding, the temperature value, the holding time, the molding pressure value, and the surface defect parameters. The surface energy of the mold is: in, Indicates the surface energy of the mold. Indicates the first surface of the mold i The percentage concentration of each atom in the atomic composition of the mold surface. Indicates the first surface of the mold i Surface enthalpy of a type of atom Indicates the first surface of the mold i The degree to which atom is surrounded by vacuum. Represents a constant. Indicates the first surface of the mold i The molar volume of a type of atom in its pure state. n This indicates the number of different types of atoms in the atomic composition of the mold surface; The surface energy of the workpiece is: in, Represents the surface energy of the workpiece. Indicates the first surface of the workpiece j The percentage concentration of a particular atom in the atomic composition of the workpiece surface. Indicates the first surface of the workpiece j Surface enthalpy of a type of atom Indicates the first surface of the workpiece j The degree to which atom is surrounded by vacuum. Indicates the first surface of the workpiece j The molar volume of a type of atom in its pure state. m This indicates the number of different types of atoms in the atomic composition of the workpiece surface; The interfacial energy between the workpiece and the mold is: in, This represents the interfacial energy between the workpiece and the mold. It is the first layer on the mold surface i Atoms are on the surface of the workpiece j The interfacial enthalpy when the atoms completely surround the surface. It is the first on the surface of the workpiece j The first type of atom is on the surface of the mold i The interfacial enthalpy when the atoms completely surround the surface; The adhesion stress value is: in, Indicates the adhesive stress value. Indicates the tensile adhesion force value. This represents the nominal contact area between the deformed workpiece and the mold before demolding. The quantitative relationship between the adhesion stress value and the molding parameters is as follows: in, Indicates reference temperature Thermodynamic adhesion work under the given conditions These are the surface defect parameters of the workpiece. Indicates the surface roughness of the workpiece. Indicates the reference roughness of the workpiece surface. This indicates the molding temperature value. Indicates the mold pressure value. For the pressure holding time, Indicates reference temperature. Indicates reference pressure. For reference, holding time, This is the proportionality coefficient. a , b , c All represent coefficients.

2. The method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to claim 1, characterized in that, The distribution parameters include at least one of the following: scattered distribution parameters, island aggregation parameters, linear flow parameters, and surface coverage parameters associated with folds. Each distribution parameter includes: the distribution size of the adhesive residue, the area percentage of the adhesive residue, and the distribution morphology of the adhesive residue.

3. The method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to any one of claims 1-2, characterized in that, The workpiece is a thermoplastic workpiece, which includes at least one of glass workpieces, plastic workpieces, and metal workpieces.

4. The method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to any one of claims 1-2, characterized in that, During the molding process of the workpiece, the upper mold and the lower mold are controlled to move relative to each other so that the molding pressure value reaches the preset forming force value and the molding pressure value is kept constant during the holding time.

5. The method for characterizing the adhesion between the workpiece and the mold interface in hot molding according to any one of claims 1-2, characterized in that, During the demolding process of the workpiece, the displacement value of the upper mold or the lower mold is collected by a displacement acquisition device to keep the moving speed of the upper mold or the lower mold constant.

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