A preparation system and method for a test sample of structural adhesive for automobiles

Abstract

The present invention discloses a system and method for preparing automotive structural adhesive test samples. The system comprises: a forming mold; a temperature control assembly; a glue gun assembly; a pressure-maintaining assembly; and a program control device. The present invention improves the demolding performance of the structural adhesive test sample by designing a middle mold and a silicon-coated film within the forming mold. The design of the temperature control assembly, glue gun assembly, pressure-maintaining assembly, and program controller achieves stable glue injection and curing, resulting in a structural adhesive test sample with good surface quality and no internal defects, thereby improving the molding quality and yield rate of the structural adhesive test sample. The resulting structural adhesive test sample has good and stable mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of automobile manufacturing technology, and in particular to a system and method for preparing a structural adhesive test sample for automobiles. The system is a method for preparing a dumbbell specimen of structural adhesive in steel-aluminum hybrid body connection technology and a special device design thereof, and is particularly suitable for high-precision molding and rapid demolding of high-viscosity structural adhesives. Background Art

[0002] Steel-aluminum hybrid body technology has been a significant development in the automotive industry in recent years. Due to its high strength and lightweight design, it has attracted considerable attention amidst the growing demand for lightweight vehicles.

[0003] At present, the main connection technologies for steel-aluminum hybrid car bodies include riveting, welding (laser welding, spot welding, etc.), bonding and mechanical connection, each with its own advantages and disadvantages. Among them, bonding can connect a variety of materials, has a simple process, does not require prefabricated holes, can reduce weight and cost, has uniform stress distribution in the adhesive layer, and has excellent performance in sealing, shock absorption, durability and fatigue resistance. It can connect complex structures and has a protective effect on electrochemical corrosion. The adhesive-riveted combined connection technology combines the advantages of advanced riveting technologies such as self-piercing riveting and flow drill riveting with adhesive bonding to form a new type of connection method. Compared with traditional pure riveted joints, adhesive-riveted composite joints have significantly improved in strength, stiffness and fatigue performance. In this composite connection, the contribution of the adhesive to the mechanical properties of the joint is particularly prominent, and the combined effect of factors such as its curing temperature, curing time and adhesive layer thickness has a significant impact on the joint performance. Therefore, in-depth research on the performance of structural adhesives is particularly important. This will help us better understand and optimize the mechanical behavior of adhesive-riveted composite joints, improve the strength of new connection processes, significantly enhance the safety performance of the entire vehicle, identify and resolve potential performance bottlenecks, and ensure the reliability and durability of adhesive-riveted composite joints in practical applications. This comprehensive research approach is of great significance for promoting technological progress in the automotive manufacturing field.

[0004] The existing structural adhesive test samples have the following shortcomings in the preparation process, making it difficult to meet the requirements of high-precision testing:

[0005] 1. Difficulty in demoulding: Since the structural adhesive is in a high-viscosity fluid state and forms a solid with high hardness after thermal curing, further processing can easily cause defects on the sample surface or even break the sample. During the curing process, the edge of the structural adhesive will produce extremely strong adhesion, and the cured colloid will adhere to the metal mold, which can easily damage the sample during demoulding.

[0006] 2. Unstable colloid extrusion: Due to the high viscosity of the colloid, it is difficult to extrude it stably by manpower alone, resulting in low extrusion efficiency and many bubbles;

[0007] 3. Uncontrollable curing pressure: Thermal expansion of the colloid causes internal defects, affecting the quality of the test sample. Summary of the Invention

[0008] The present invention can solve the above-mentioned defects existing in the preparation process of automotive structural adhesive test samples in the prior art by providing a preparation system and preparation method for automotive structural adhesive test samples.

[0009] To solve the above technical problems, the present invention provides a system for preparing automotive structural adhesive test samples, comprising:

[0010] A molding die, comprising an upper mold, a middle mold, and a lower mold; wherein the middle mold has a colloid molding cavity and a glue injection port and an overflow port connected thereto; the middle mold is a Teflon material mold, with silicon-coated films laid on both sides;

[0011] A temperature control component is installed in a groove at the bottom of the lower mold;

[0012] A glue gun assembly, which is detachably connected to the glue injection port and is used to inject structural glue into the colloid molding cavity;

[0013] A pressure-maintaining component, which is detachably connected to the glue injection port and the overflow port and is used to stabilize the pressure in the molding die during the glue injection and curing processes;

[0014] A program control device is connected to the temperature control component, the glue gun component and the pressure maintaining component by signal.

[0015] In a preferred embodiment of the present invention, the upper mold and the middle mold are also provided with dovetail lifting plates.

[0016] In a preferred embodiment of the present invention, the glue injection port and the overflow port are located at two ends of the colloid molding cavity, and the overflow port is connected to a vertical threaded port that passes through the upper mold.

[0017] In a preferred embodiment of the present invention, the temperature control component includes a thermocouple, an electric heating pipe and a cooling water channel; wherein the thermocouple and the switch valves of the electric heating pipe and the cooling water channel are respectively connected to the program control device signal.

[0018] In a preferred embodiment of the present invention, the glue gun assembly includes a glue gun body, a pressure plate and a speed regulating motor; wherein, the glue outlet end of the glue gun body is threadedly connected to the glue injection port, and the other end thereof is installed with the pressure plate, and the speed regulating motor is connected to the pressure plate to drive the pressure plate to squeeze glue toward the glue outlet end; the speed regulating motor is signal-connected to the program control device.

[0019] In a preferred embodiment of the present invention, a preheating coil is further provided around the glue gun body for preheating the glue in the glue gun body.

[0020] In a preferred embodiment of the present invention, the pressure maintaining component includes a pressure-controlling overflow tank, the open end of which is connected to the glue injection port or the overflow port; a pressure-regulating piston, a pressure-regulating spring and a pressure-regulating screw are installed in the pressure-controlling overflow tank from the open end to the other end; the pressure-regulating screw passes through the pressure-controlling overflow tank and is connected to a pressure calculator, and the pressure calculator is connected to the signal of the program control device.

[0021] In a preferred embodiment of the present invention, a protective air hole is further opened on one side of the pressure-controlling overflow tank, and the protective air hole is located below the pressure-regulating screw when the pressure-controlling overflow tank is in a maximum pressure state.

[0022] To solve the above technical problems, the present invention further provides a method for preparing a test sample of an automotive structural adhesive, which uses the above preparation system and includes the following steps:

[0023] (1) Mold preheating: Turn on the temperature control component to preheat the molding mold to 40-60°C;

[0024] (2) Glue injection: The pressure holding assembly and the glue gun assembly are respectively installed on the overflow port and the glue injection port. The program control device adjusts the glue extrusion speed of the glue gun assembly through a PID algorithm based on the real-time pressure data fed back by the pressure calculator of the pressure holding assembly, and squeezes glue into the molding die;

[0025] (3) Heating and curing molding: disassembling the glue gun assembly, installing the pressure-maintaining assembly on the glue injection port, adjusting the upper pressure limits of the two groups of the pressure-maintaining assemblies, and completing the heating and curing process through the temperature control assembly;

[0026] (4) Cooling and demoulding: After the curing is completed, the mold is cooled to below 50° C., and the mold is opened and demoulded to obtain the automotive structural adhesive test sample.

[0027] In a preferred embodiment of the present invention, in step (3), the temperature control component monitors the temperature of the forming mold in real time, and dynamically adjusts the heating power using a PID algorithm through a PID controller in the temperature control component.

[0028] The beneficial effects of the present invention are as follows: a preparation system for a structural adhesive test sample for an automobile of the present invention improves the demolding performance of the structural adhesive test sample through the design of a middle layer mold and a silicon-coated film in a molding mold; stable glue injection and curing are achieved through the design of a temperature control component, a glue gun component, a pressure-maintaining component and a program controller, so that the surface quality of the prepared structural adhesive test sample is good and the internal defects are free, thereby improving the molding quality and yield of the structural adhesive test sample; the mechanical properties of the obtained structural adhesive test sample are good and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a schematic diagram of the three-dimensional structure of the forming mold in the preparation system of the automotive structural adhesive test sample of the present invention. Figure 1 ;

[0030] Figure 2 This is a schematic diagram of the three-dimensional structure of the forming mold in the preparation system of the automotive structural adhesive test sample of the present invention. Figure 2 ;

[0031] Figure 3 1 is a schematic diagram of the exploded structure of the molding die shown;

[0032] Figure 4 Schematic diagram of the structure of the middle layer mold shown;

[0033] Figure 5 Schematic diagram of the combined structure of the molding die, temperature control component and program control device;

[0034] Figure 6 is a flow chart of temperature feedback regulation control of the molding die shown;

[0035] Figure 7 Schematic diagram of the combined structure of the molding die and glue gun assembly;

[0036] Figure 8 Schematic diagram of pressure-maintaining feedback regulation control of the glue gun assembly shown;

[0037] Figure 9 Schematic diagram of the combined structure of the forming die and the pressure holding component;

[0038] Figure 10 Schematic diagram of the internal structure of the pressure-controlled overflow tank shown;

[0039] Figure 11 is a schematic diagram of the tensile results of the test sample prepared in Example 2;

[0040] The markings of the components in the accompanying drawings are as follows:

[0041] 10. Molding mold, 11. Upper mold, 12. Middle mold, 13. Lower mold, 14. U-bolt slot, 15. Dovetail lifting plate, 16. Silicone film, 121. Colloidal molding cavity, 122.

[0042] Glue injection port, 123. Overflow port, 124. Positioning pile, 125. Vertical thread port, 131. Mold positioning anchor hole, 132. Nut limit slot, 133. Temperature control component installation slot;

[0043] 20. Temperature control components, 21. Thermocouple, 22. Electric heating pipe, 23. Cooling water channel,

[0044] 30. Glue gun assembly, 31. Glue gun body, 32. Press plate, 33. Speed ​​regulating motor, 34. Preheating coil,

[0045] 40. Pressure control overflow tank, 41. Pressure regulating piston, 42. Pressure regulating spring, 43. Pressure regulating screw, 44. Protective air hole, 45. Pressure calculator;

[0046] 50. Program control device. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0048] Example 1

[0049] The present invention discloses a system for preparing a test sample of a structural adhesive for automobiles, comprising a forming die 10, a temperature control component 20, a glue gun component 30, a pressure maintaining component and a program control device 50.

[0050] like Figure 1-4 As shown, the molding die 10 comprises an upper mold 11, a middle mold 12, and a lower mold 13. Both the upper mold 11 and the lower mold 13 are made of high-strength mold steel to ensure overall rigidity and stability. The middle mold 12 is made of Teflon, which resists adhesion to the cured structural adhesive, facilitating demolding of the molded structural adhesive test specimens and improving molding quality.

[0051] Specifically, eight U-shaped bolt slots 14 are provided on both side edges of the forming die 10 for positioning and fastening bolts, thereby improving the convenience and accuracy of installing the forming die on a machine tool.

[0052] The lower mold 13 is designed with four precise mold positioning anchor holes 131 on its edge for precise positioning and installation of the forming mold 10. The bottom of the lower mold 13 also has nut retaining grooves 132 and a temperature control assembly mounting groove 133. The structural design of the lower mold 13 enables quick and accurate positioning and installation of the entire forming mold.

[0053] The upper mold 11 and the middle mold 12 are both installed with dovetail lifting plates 15, which facilitate the rapid removal of the middle mold 12 from the forming mold, thereby realizing rapid disassembly and sampling of the forming mold.

[0054] The middle mold 12 has a colloid forming cavity 121, specifically a standard dumbbell-shaped forming cavity in the ASTM D638 standard. One end of the colloid forming cavity 121, such as Figure 4The right end shown is an open end and is connected to a horizontal glue injection port 122, which is a horizontal threaded port. The other end of the colloid molding cavity 121, i.e. Figure 4 The left end is a closed end with an overflow port 123, which is connected to a vertical threaded port 125 arranged vertically, and the vertical threaded port 125 passes through the upper mold 11 upward. The overflow port 123 is used to adjust the pressure and exhaust in the colloid molding cavity 121 to ensure that the colloid moves in one direction to fill the cavity, so as to ensure the integrity and molding quality of the molding. In addition, the area where the center line of the middle mold 12 is located is also provided with four positioning piles 124 arranged at intervals, and the upper mold 11 is provided with correspondingly designed positioning grooves. Specifically, the positioning piles 124 are cylindrical with a diameter of 5 mm, and are clearance-matched with the positioning grooves of the upper mold 11 to determine the position of the middle mold 12 and ensure that the molds are accurately aligned.

[0055] Additionally, a 0.1-0.3mm thick layer of silicone film 16, made of a polysiloxane composite material, is placed on both sides of the middle mold 12, between the upper mold 11, and the lower mold 13. This film exhibits strong polymer repellency, preventing adhesion to the cured structural adhesive. Furthermore, its thinness, strength, and density make it an ideal material for the interlayer of structural adhesive molding molds.

[0056] The material design of the middle mold 12 and the use of silicon-coated films 16 on both sides thereof can effectively prevent the structural adhesive from adhering to the mold after molding, facilitate demolding, thereby improving the demolding effect and preventing adhesion to the metal mold to affect the quality of the test sample after molding and the accuracy of the test results.

[0057] like Figure 5 As shown, the temperature control assembly 20 is installed in a groove at the bottom of the lower mold 13, specifically in the temperature control assembly installation groove 133. The temperature control assembly 20 includes a thermocouple 21, an electric heating pipe 22 and a cooling water channel 23.

[0058] The electric heating pipe 22 and cooling water channel 23 are arranged in a rectangular shape, with the cooling water channel 23 located inside the electric heating pipe 22. The thermocouples 21 are installed on the lower mold and symmetrically distributed outside the electric heating pipe 22 to monitor the temperature of the molding mold in real time. The thermocouples 21 and the on / off valves of the electric heating pipe 22 and cooling water channel 23 are each connected to the program control device 50 for signal communication.

[0059] The program control device 50 contains a small computer that can set the required curing temperature and control the current in the electric heating pipe and the opening and closing of the water flow in the cooling water channel 23. The program control device 50 also has a PID regulator that can accurately control the electric heating and water cooling based on the temperature signal fed back by the thermocouple 21 through the PID algorithm to achieve constant temperature control. The specific temperature feedback control flow chart is shown in the attached figure. Figure 6 shown.

[0060] like Figure 7 As shown, the glue gun assembly 30 is detachably connected to the glue injection port 122 and is used to inject structural glue into the colloid molding cavity 121. Specifically, the glue gun assembly 30 includes a glue gun body 31, a pressure plate 32, a speed regulating motor 33 and a preheating coil 34. The glue outlet end (i.e., the glue gun nozzle) of the glue gun body 31 is threadedly connected to the glue injection port 122, and the other end is installed with the pressure plate 32. The speed regulating motor 33 is connected to the pressure plate 32 to drive the pressure plate 32 to squeeze glue toward the glue outlet end to ensure that the glue gun body 31 squeezes the structural glue into the molding mold at a stable speed. The preheating coil 34 surrounds the glue gun body 31 and preheats and softens the structural glue therein to reduce the viscosity of the colloid and increase the fluidity of the colloid. The speed regulating motor 33 is connected to the program control device 50 by signal, and the program control device 50 can regulate the speed of the speed regulating motor 33 to adjust the glue injection speed.

[0061] The pressure maintaining assembly is detachably connected to the glue injection port 122 and the vertical threaded port 125 , and is used to stabilize the pressure in the molding die during the glue injection and curing processes.

[0062] The pressure maintaining component is a pressure control overflow tank 40, and the open end of the pressure control overflow tank 40 is threadedly connected to the glue injection port 122 or the vertical threaded port. Figure 10 As shown, the pressure-controlled overflow tank 40 is equipped with a pressure-regulating piston 41, a pressure-regulating spring 42, and a pressure-regulating screw 43, sequentially installed from the open end toward the other end. The pressure-regulating spring 42 is positioned between the pressure-regulating piston 41 and the pressure-regulating screw 43, which extends through the pressure-controlled overflow tank 40. The pressure-regulating screw 43 is also connected to a pressure calculator 45, which calculates the pressure within the pressure-controlled overflow tank 40 based on the telescopic beam of the pressure-regulating screw, thereby monitoring the pressure within the colloid molding cavity 121 in real time.

[0063] The pressure calculator 45 is connected to the program control device 50 by signal transmission. The program control device 50 can pre-set the pressure in the pressure-controlled overflow tank 40. The pressure regulating screw 43 is rotatable. By rotating the pressure regulating screw 43, the tension of the pressure regulating spring 42 can be adjusted to achieve the set pressure value with high accuracy.

[0064] A protective air hole 44 is also provided on one side of the pressure-control overflow tank 40. This hole is located below the pressure-regulating screw 43 when the tank is at maximum pressure. When the internal pressure of the pressure-control overflow tank exceeds the set pressure, the pressure-regulating piston 41 is squeezed to a position above the protective air hole 44. This allows the protective air hole 44 to communicate with the outside world, prioritizing the exhaust of gas. This prevents the pressure-regulating spring from failing due to overload and improves system safety. This configuration precisely controls the pressure within the mold, ensuring pressure stability and safety during injection and curing, thereby improving the molding quality of test specimens.

[0065] The protective air hole is located below the pressure regulating screw, which can be used when the pressure exceeds the limit. Specifically, during the glue injection process, the overflow port 123 is threadedly connected to the pressure control overflow tank 40, the glue injection port 122 is connected to the glue gun body in the glue gun assembly 30, and the speed regulating motor 33 is connected to the program control device. The pressure calculator 45 provides real-time feedback of the pressure in the colloid molding cavity to the program control device 50. The program control device 50 adjusts the speed of the speed regulating motor 33 through the PID controller, thereby adjusting the glue injection speed according to the real-time pressure in the colloid molding cavity, effectively reducing the problem of gas inside the test sample, and significantly improving the finished product quality of the structural adhesive test sample. The glue injection speed adjustment diagram is shown in FIG. Figure 8 shown.

[0066] like Figure 9 As shown, during the curing molding process, the glue injection port 122 is threadedly connected to another pressure-controlled overflow tank 40. During the curing process, the internal control of the molding die expands due to heat, gathers inside the pressure-controlled overflow tank 40 and squeezes the pressure-regulating piston 41. The pressure-regulating piston 41 is limited in displacement by the tensioning force of the pressure-regulating spring 42, thereby achieving the effect of controlling the internal pressure of the mold. When the internal pressure of the pressure-controlled overflow tank 40 is higher than the set pressure, the position of the pressure-regulating piston 41 is squeezed higher than the protection position. At this time, the protective air hole 44 leaks out to connect to the outside world, and the excess air is discharged for pressure regulation. The system ensures the stability of the mold during the curing process by precisely controlling the pressure in the mold, thereby improving the quality of the sample.

[0067] Example 2

[0068] Taking the 1840C one-component epoxy adhesive widely used in the automotive manufacturing industry as an example, the preparation process of its test sample is explained.

[0069] 1. Work environment preparation and material pretreatment

[0070] First, the working environment is thoroughly purified to ensure it meets sterile and dust-free standards. Two precisely measured pieces of silicon-coated film are cut and preheated using the preheating coil 34 in the glue gun assembly 30 to improve the fluidity of the colloid and reduce adhesion.

[0071] 2. Assembly and debugging of mold system

[0072] 2.1 Mould positioning and fixing

[0073] The lower mold 13 is firmly fixed to the workbench by high-strength bolts through precise mold positioning anchor holes 131 to ensure its stability and accuracy during operation.

[0074] 2.2 Installation of hot and cold runners and thermocouples

[0075] The cooling water channel 23 and the thermocouple 21 are precisely installed in the temperature control component installation groove 133 of the lower mold 13 to ensure that they are tightly integrated with the lower mold 13 to provide accurate data support for subsequent temperature control.

[0076] 2.3 Laying of silicon-coated film

[0077] A layer of processed silicon-coated film 16 with a thickness of 0.2 mm is laid on the lower mold 13 to reduce the adhesion between the mold and the colloid and improve the demoulding efficiency.

[0078] 2.4 Assembly of the middle layer mold

[0079] The middle mold 12 is installed on the lower mold 13 and the silicon-coated film 16 thereon through precise positioning holes, and a glue gun adapter is installed to ensure the integrity and functionality of the mold structure.

[0080] 2.5 Laying of top film

[0081] A layer of silicon-coated film 16 is again laid on the middle mold 12 to further improve the demoulding effect and the sealing performance of the mold.

[0082] 2.6 Installation of overflow transfer interface and upper mold

[0083] Vertical threaded ports, namely overflow ports 123 and upper mold 11, are installed on the middle mold 12 and the silicon-coated film 16 thereon to ensure the sealing and functionality of the mold system.

[0084] 2.7 Tightening and inspection of the entire mold

[0085] High-strength fastening bolts are used to tighten the entire forming mold, and a precise inspection mechanism is used to ensure that the mold body does not loosen or shift, ensuring the stability and accuracy of the mold.

[0086] 3. Colloid injection and curing process

[0087] 3.1 Preheating the mold

[0088] Turn on the temperature control component 20, set the preheating temperature to 50℃±5℃, the heating time to 5 minutes, and keep warm before curing. This temperature can reduce the viscosity of the 1840℃ one-component epoxy adhesive, making the colloid have good fluidity so that it can fully adhere to the inner surface of the mold.

[0089] 3.2 Glue gun assembly connection

[0090] The pressure-controlled overflow tank 40 is threadedly installed on the overflow port 123, and the glue gun system is threadedly connected to the glue injection port 122. At the same time, the real-time pressure of the pressure-controlled overflow tank 40 is input into the program control device 50. According to the actual sample size, the pressure regulating screw 43 of the pressure-controlled overflow tank 40 is adjusted so that the upper limit of the pressure that the pressure-controlled overflow tank 40 can withstand is 0.3MPa, and the glue extrusion speed is set to between 0.8ml / s-1ml / s. The structural glue is squeezed into the molding mold evenly and stably, and the total amount squeezed is 11ml. According to the real-time pressure data of the pressure calculator 45 at the overflow port 123, the speed of the speed regulating motor 33 in the glue gun assembly can be closed-loop controlled to control the colloid inflow speed so that the overall pressure in the mold is controlled at about 0.25MPa. Maintaining pressure in the mold can increase the density of the glue sample, effectively reduce the bubble defects inside the molded glue sample, and ensure the accuracy and yield of the test sample.

[0091] 3.3 Installation of pressure-controlled overflow tank at injection port

[0092] After glue injection is complete, remove the glue gun assembly 30 and install a pressure-controlled overflow tank 40 horizontally above the glue injection port. Adjust the upper pressure limits of both the overflow port 123 and the glue injection port 122 to 0.5 MPa. This ensures pressure control during the curing process, avoids defects in the specimen caused by thermal expansion of the glue, and improves specimen quality.

[0093] 3.4 Setting and executing curing parameters

[0094] In the program control device 50, according to the 1840C one-component epoxy adhesive process manual, the curing temperature is set to 180°C, the heating time is 5 minutes, and the curing time is 30 minutes, and the curing program is started. At this time, the molding mold will gradually heat up to the set temperature and maintain it at 180°C to ensure that the physical properties of the colloid meet the expected standards.

[0095] 3.5 Cooling and disassembly

[0096] After the curing time reaches 30 minutes, the curing is completed. The PID controller (PID algorithm) in the program control device 50 controls the flow of cooling water to cool the molding die to 50°C and keep it warm. This temperature is conducive to the demolding of the 1840C single-component epoxy adhesive dumbbell specimen after molding. After the curing is completed, the mold fastening bolts and the pressure-controlled overflow tank can be removed to ensure the integrity and safety of the specimen.

[0097] 4. Sample removal and quality inspection

[0098] Using the designed dovetail lifting plate 15, the upper mold 11 and the middle mold 12 are carefully and slowly removed one by one. The middle mold 12 and the molded specimen are now protected by the silicone films 16 on both sides. After peeling off the silicone films, the cured dumbbell-shaped specimen can be easily removed because the structural adhesive and the Teflon material used in the middle mold 12 do not adhere. It is then placed in a safe location and allowed to rest for a period of time to dissipate residual heat, resulting in a dumbbell-shaped test specimen.

[0099] The dumbbell-shaped test sample prepared by the method is easy to demould, does not stick to the mold, has good surface quality, no bubbles, no mold sticking damage, no internal defects, and has uniform and stable quality.

[0100] Ten groups of test samples were prepared in parallel using the above method and subjected to tensile performance tests. The Young's modulus of the 1840C single-component epoxy structural adhesive test sample was 2505MPa, while the official data was 2270MPa; the breaking stress was 35.1MPa, while the official data was 36MPa. The standard deviation of the Young's modulus of the 10 groups of test samples was ±15MPa, and the standard deviation of the breaking stress was ±0.3MPa, which showed good consistency. This shows that the method and equipment of the present invention are feasible and reusable, filling the gap in the prior art. The test results are shown in the attached figure. Figure 11 shown.

[0101] The present invention has the following advantages:

[0102] 1. Through the dumbbell-shaped cavity design and overflow port design of the middle mold, the colloid flow direction is fixed, and the rapid one-piece molding preparation of dumbbell rubber samples can be achieved.

[0103] 2. The middle mold is made of Teflon material, and the upper and lower molds are designed to be made of mold steel material. Silicone film is used to solve the demoulding problem after the colloid is cured.

[0104] 3. Through the design of temperature control components, dumbbell rubber sample molding + curing integrated production is achieved, ensuring the temperature and time during the curing process, avoiding the problem of insufficient curing due to unstable furnace temperature, and improving the yield of rubber samples.

[0105] 4. Through the design of the glue extrusion device, the colloid is preheated before extrusion, which enhances the fluidity of the colloid and thus improves the integrity of the colloid filling the mold; through the design of the extrusion motor to ensure the extrusion flow rate, the generation of bubbles is reduced and the quality of the glue sample is improved.

[0106] 5. The design of the pressure-controlled overflow tank ensures the pressure inside the cavity during the colloid curing process, thereby avoiding the generation of bubbles inside the colloid due to volume expansion during the curing process.

[0107] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A system for preparing test samples of automotive structural adhesives, characterized in that: include: A molding die, comprising an upper mold, a middle mold, and a lower mold; wherein the middle mold has a colloid molding cavity and a glue injection port and an overflow port connected thereto; the middle mold is a Teflon material mold, with silicon-coated films laid on both sides; A temperature control component is installed in a groove at the bottom of the lower mold; A glue gun assembly, which is detachably connected to the glue injection port and is used to inject structural glue into the colloid molding cavity; A pressure-maintaining component, which is detachably connected to the glue injection port and the overflow port and is used to stabilize the pressure in the molding die during the glue injection and curing processes; A program control device is connected to the temperature control component, the glue gun component and the pressure maintaining component by signal.

2. The preparation system according to claim 1, characterized in that: The upper mold and the middle mold are also provided with dovetail lifting plates.

3. The preparation system according to claim 1, characterized in that: The glue injection port and the overflow port are located at two ends of the colloid forming cavity, and the overflow port is connected to a vertical threaded port that passes through the upper mold.

4. The preparation system according to claim 1, characterized in that: The temperature control component includes a thermocouple, an electric heating pipe and a cooling water channel; wherein the thermocouple and the switch valves of the electric heating pipe and the cooling water channel are respectively connected to the program control device by signal.

5. The preparation system according to claim 1, characterized in that: The glue gun assembly includes a glue gun body, a pressure plate and a speed regulating motor; wherein, the glue outlet end of the glue gun body is threadedly connected to the glue injection port, and the other end thereof is installed with the pressure plate, and the speed regulating motor is connected to the pressure plate to drive the pressure plate to squeeze glue toward the glue outlet end; the speed regulating motor is signal-connected to the program control device.

6. The preparation system according to claim 5, characterized in that: The glue gun body is also surrounded by a preheating coil for preheating the colloid in the glue gun body.

7. The preparation system according to claim 1, characterized in that: The pressure maintaining component includes a pressure-controlling overflow tank, the open end of which is connected to the glue injection port or the overflow port; a pressure-regulating piston, a pressure-regulating spring and a pressure-regulating screw are installed in the pressure-controlling overflow tank from the open end to the other end; the pressure-regulating screw passes through the pressure-controlling overflow tank and is connected to a pressure calculator, and the pressure calculator is connected to the program control device signal.

8. The preparation system according to claim 7, characterized in that: A protective air hole is further provided on one side of the pressure-controlling overflow tank, and the protective air hole is located below the pressure-regulating screw when the pressure-controlling overflow tank is in a maximum pressure state.

9. A method for preparing a test sample of a structural adhesive for automobiles, characterized in that: The preparation system according to any one of claims 1 to 8 comprises the following steps: (1) Mold preheating: Turn on the temperature control component to preheat the molding mold to 40-60°C; (2) Glue injection: The pressure holding assembly and the glue gun assembly are respectively installed on the overflow port and the glue injection port. The program control device adjusts the glue extrusion speed of the glue gun assembly through the PID algorithm according to the real-time pressure data fed back by the pressure calculator of the pressure holding assembly, and squeezes glue into the molding die; (3) Heating and curing molding: disassembling the glue gun assembly, installing the pressure holding assembly on the glue injection port, adjusting the upper pressure limit values ​​of the two groups of the pressure holding assemblies, and completing the heating and curing process through the temperature control assembly; (4) Cooling and demolding: After the curing is completed, the mold is cooled to below 50°C, and the mold is opened and demolded to obtain the automotive structural adhesive test sample.

10. The preparation method according to claim 9, characterized in that In step (3), the temperature control component monitors the temperature of the forming mold in real time, and dynamically adjusts the heating power using a PID algorithm through a PID controller in the temperature control component.

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