CN-122008476-A - Workpiece processing method and system based on liquid encapsulation integrated forming

CN122008476ACN 122008476 ACN122008476 ACN 122008476ACN-122008476-A

Abstract

The invention discloses a workpiece processing method and system based on liquid encapsulation integrated forming, and belongs to the technical field of precision manufacturing. The method comprises the steps of constructing a chemical anchor point layer with active functional groups, placing a pretreated material into a mould system as an insert, injecting liquid silicone rubber, controlling the vulcanization reaction rate at the surface of the material to be lower than that of a central area of a cavity in the vulcanization process, enabling the vulcanization conversion rate at the surface to be delayed in the central area, enabling the active functional groups in the liquid silicone rubber to diffuse to the chemical anchor point layer and generate covalent crosslinking during the delay period to form a cross-interface chemical bonding network, and finally cooling and demoulding. According to the invention, the chemical anchor point layer is constructed on the material surface, and the interface hysteresis reaction in the vulcanization process is controlled, so that the covalent bonding of the liquid silicone rubber and the heterogeneous material on the molecular level is realized, the interface stress mismatch caused by physical assembly is eliminated, the interface bonding strength and the sealing reliability are obviously improved, and the production flow is simplified.

Inventors

ZHENG CHUANCHAO
Tang Youxia
JIANG ZHIJUN
LI XIONGWEI
REN YAJUN

Assignees

内江鸿图超越科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260331

Claims (10)

1. A workpiece processing method based on liquid encapsulation integrated forming is characterized by comprising the following steps: step S1, preprocessing the surface to be combined of the materials to be processed, wherein the preprocessing comprises surface activation processing and interfacial chemical modification so as to construct a chemical anchor point layer with active functional groups on the surface to be combined; s2, placing the pretreated material into a mould system as an insert, and enabling the surface to be combined of the material and the mould surface to jointly enclose a closed glue injection cavity; s3, injecting liquid silicone rubber into the glue injection cavity, so that the liquid silicone rubber is directly filled on the surface to be combined of the materials; Step S4, controlling the vulcanization reaction rate of the surface to be combined of the materials to be lower than that of the central area of the glue injection cavity in the vulcanization process of the filled liquid silicone rubber, enabling the vulcanization reaction conversion rate of the surface to be combined to lag behind the central area, and enabling active functional groups in the liquid silicone rubber to diffuse to a chemical anchor point layer and to be covalently crosslinked with the chemical anchor point layer during the lag period to form a cross-interface chemical bonding network; And S5, cooling and demolding the vulcanized workpiece.
2. The method for processing the workpiece based on the liquid encapsulation integrated forming is characterized in that a plasma treatment technology is adopted in surface activation treatment, polar functional groups are introduced to the surface of a material through high-energy particle bombardment, so that the surface energy of the material is improved to a degree sufficient for wetting and spreading with a coupling agent coated subsequently, an interface is chemically modified to coat the activated surface with a silane coupling agent, the molecular structure of the silane coupling agent comprises a first active group and a second active group, the first active group is used for forming covalent bond connection with the polar functional groups on the surface of the material, and the second active group is used as a chemical anchor layer for carrying out addition reaction with the active functional groups of the liquid silicone rubber in a subsequent vulcanization process.
3. The method for processing a workpiece based on liquid encapsulation integrated molding as set forth in claim 2, wherein the thickness of the coating of the coupling agent is determined according to an interfacial stress transfer theory, and is set such that the coupling agent layer can completely cover microscopic defects on the surface of the material and form a continuous stress buffer layer at the interface, while the cohesive strength of the coupling agent layer is not lower than the bonding strength between the interface of the liquid silicone rubber and the coupling agent.
4. The method for processing the workpiece based on the liquid encapsulation integrated molding of claim 1, wherein when the pretreated material is placed in a mold system, a visual positioning compensation technology is adopted, wherein characteristic point coordinates of the surface of the material are collected, deviation between actual pose and theoretical pose of the material is calculated based on an image processing algorithm, and the placement position of the material is compensated in real time according to the deviation, so that the attaching gap between the material and the mold is smaller than a critical gap value for leakage of liquid silicone rubber under injection pressure.
5. The method for processing the workpiece based on the liquid encapsulation integrated molding of claim 1, wherein the mold system is provided with an elastic sealing compensation structure in an edge area contacted with the material, the elastic sealing compensation structure generates elastic deformation under the action of mold clamping pressure, sealing specific pressure is applied to the surface of the material, and the sealing specific pressure is set to be larger than the multiple of the peak value of the injection pressure of the liquid silicone rubber according to the Hertz contact theory so as to ensure that a sealing interface is always in an elastic contact state in a mold clamping force fluctuation range.
6. The method for processing the workpiece based on the liquid encapsulation integrated molding of claim 1 is characterized in that a sectional injection control strategy is adopted in the injection process of the liquid silicone rubber, the first stage is used for high-speed filling at a shearing rate higher than a shearing and thinning critical value of the liquid silicone rubber, the shearing and thinning effect is utilized to reduce the viscosity of the rubber material so as to realize quick mold filling, the second stage is used for decelerating and penetrating at a shearing rate lower than the shearing and thinning critical value so that the rubber material penetrates into microscopic pores on the surface of the material at the low shearing rate, and the third stage is used for maintaining the pressure at a preset pressure maintaining pressure so as to compensate the volume shrinkage of the rubber material in the subsequent vulcanization process.
7. The method for processing a workpiece based on liquid encapsulation integrated molding as set forth in claim 1, wherein the injection process is controlled based on a rheology constitutive equation of liquid silicone rubber: Wherein, the In order to obtain the apparent viscosity of the product, In order to be able to determine the temperature, In order to achieve a shear rate, Is zero shear viscosity and satisfies the WLF equation in relation to temperature, For a critical shear stress of the material into the shear-thinning region, Is a non-Newton index; The current shear rate and apparent viscosity are reversely pushed by monitoring the displacement and pressure of the injection screw in real time, and the injection speed is dynamically regulated according to a rheology constitutive equation, so that the filling process is always in a preset shear rate window.
8. The method and system for processing the workpiece based on the liquid encapsulation integrated molding are characterized in that the specific method for controlling the vulcanization reaction rate at the surface to be combined to be lower than that of the central area is characterized in that a zonal independent temperature control technology is adopted, differential thermal power is applied to different areas of the glue injection cavity, the temperature at the surface to be combined is lower than that of the central area, a temperature gradient window is formed, the vulcanization reaction conversion rate at the surface to be combined is delayed to the central area by utilizing the influence of the temperature on the vulcanization reaction rate, the delay time is determined according to the diffusion coefficient of an active functional group in liquid silicone rubber and the equivalent diffusion distance of a chemical anchor point layer, and the diffusion-reaction coupling condition is set.
9. The method and system for integrally forming a workpiece by liquid encapsulation according to claim 8, wherein the control of the vulcanization process is based on Kamal-Sourour reaction kinetic model: Wherein, the For the conversion rate of the vulcanization reaction, 、 For reaction rate constants and obeying the arrhenius equation, 、 Is a reaction series parameter; Temperature distribution data are obtained through multi-point thermocouples buried at the joint surfaces of the die cavity and the materials, and zonal heating power is dynamically adjusted based on a reaction kinetic model, so that the vulcanization process is carried out according to a preset conversion rate curve, and the concentration of active functional groups of the sizing material at the interface is maintained to be higher than that of the central area of the die cavity in a hysteresis period.
10. A liquid encapsulation integrated workpiece processing system for performing the method of any of claims 1 to 9, the system comprising: The surface treatment and coating subsystem is used for carrying out plasma activation treatment and coupling agent coating on the surfaces to be combined of the materials so as to construct a chemical anchor point layer on the surfaces of the materials; The integrated die unit comprises a fixed die, a movable die, a die temperature control assembly and a material positioning mechanism, wherein the material positioning mechanism is used for fixing materials at a preset position, so that a to-be-combined surface of the materials and a die surface jointly form a physical boundary of a closed glue injection cavity, and the die temperature control assembly adopts a regional independent temperature control framework and can apply differential thermal power to different regions of the glue injection cavity; the raw material storage and transportation and metering unit is used for storing A, B component liquid silicone rubber raw materials and precisely outputting the liquid silicone rubber raw materials according to a preset proportion; the mixing and injection execution unit is connected with the raw material storage and transportation and metering unit and is used for injecting the mixed sizing material into the sizing material injection cavity; The central control and real-time monitoring system is respectively connected with the surface treatment and coating subsystem, the integrated die unit, the raw material storage and transportation and metering unit and the mixing and injection execution unit in a signal way, the rheological control module and the vulcanization control module are integrated in the central control and real-time monitoring system, the rheological control module is solidified with a rheological constitutive equation of liquid silicone rubber and is used for dynamically correcting an injection speed curve according to injection parameters fed back in real time, and the vulcanization control module is solidified with a vulcanization reaction dynamics model and is used for dynamically adjusting partition heating power according to real-time temperature data so as to realize differential vulcanization control of the surface to be combined and a central area.

Description

Workpiece processing method and system based on liquid encapsulation integrated forming Technical Field The invention belongs to the technical field of precision manufacturing, and particularly relates to a workpiece processing method and system based on liquid encapsulation integrated forming. Background With the continuous evolution of the precision manufacturing field and the wide application of high-performance elastomer material technology, liquid silicone rubber (Liquid Silicone Rubber, abbreviated as LSR) has become an indispensable key material in the fields of automotive electronics, medical equipment, high-end consumer electronics, aerospace and the like due to its excellent thermal stability, excellent biocompatibility, chemical inertness and excellent electrical insulation property. In the current industrial practice, the liquid silicone rubber injection molding process has formed a relatively mature set of technical systems. The system generally covers the whole process from the precise metering and static mixing of A, B double-component raw materials, to the conveying of the double-component raw materials to an injection unit through a pressurizing system, and the double-component raw materials are injected into a preheating die cavity under the precise temperature control of a cold runner technology, and finally the cross-linking and vulcanizing are completed under the high-temperature and high-pressure environment. Specifically, in order to ensure the physicochemical properties of the molded product, the accuracy of the proportioning is extremely emphasized in the prior art, the component A (containing the base sizing material and the crosslinking agent) and the component B (containing the base sizing material and the platinum catalyst) are generally controlled within a very small error range by a high-precision gear pump or a piston pump, and the runner temperature is maintained between 30 ℃ and 50 ℃ by using a cold runner system, so that the sizing material is prevented from being vulcanized in advance before entering a cavity, and the efficient production of the runner-free waste is realized. However, while the existing LSR molding technology exhibits extremely high process maturity in manufacturing single material silicone articles, this traditional production model is facing serious technical challenges as contemporary industrial products evolve toward miniaturization, high integration, and extreme operating reliability. In the prior art paradigm, the design and manufacturing logic of the mold is focused entirely on the geometry of the silicone article itself, i.e. "first formed and then assembled". This means that the silica gel function and the hard substrate (e.g. plastic housing, metal structural part, etc.) to be combined with it are in a completely decoupled state on the production chain. After the vulcanization molding of the silica gel piece is completed, the silica gel piece is fixed on the target material by means of a subsequent secondary assembly process, gluing and bonding or mechanical embedding. The decoupled production logic not only significantly lengthens the process flow and increases the labor and equipment cost, but also has a deeper problem that the decoupled production logic introduces technical contradiction which is difficult to overcome in the principle level. The root cause is that the split process causes the essential defects of interface binding force and sealing reliability. Firstly, the preformed silica gel piece can generate unavoidable shrinkage stress and dimensional slight difference after demolding, and the hard base material has tolerance in the processing process, when the two are physically assembled, the contact stress distribution on the microscopic level is extremely uneven, and a stress concentration area or a tiny gap is extremely easy to form, so that the sealing failure is induced when the pressure fluctuation, the thermal cycle or the mechanical vibration is received. Secondly, the fully vulcanized silicone rubber has extremely low surface energy and high chemical inertness, molecular chains between interfaces are in a relatively stable crosslinking state, and if the fully vulcanized silicone rubber is combined with materials through an adhesive, the interface wettability is poor, strong chemical bonding is difficult to form, and the bonding strength is quickly attenuated under extreme environments (such as high humidity and heat, solvent soaking or cyclic loading) because the bonding strength is often maintained only by means of intermolecular force or micro-mechanical embedding. Further, from a precision-molded rheology and thermodynamics perspective, the prior art is struggling to handle the sealing requirements of complex shaped structures. Because the silica gel piece and the base material are manufactured separately, the complete fitting of the interface can not be ensured in the assembly process, and particularly when the assembly e