A method for avoiding stress marks on the surface of a two-color injection molded ins part

Abstract

The present application relates to the technical field of double-color injection molding INS film piece, and discloses a method for avoiding surface stress marks of double-color injection molding INS parts, comprising the following steps: S1, material preparation, S2, product preparation, S3, PC material thickness optimization, the thickness of PC material is designed as 2.5-3 mm, and the thickness of PC material is 1:30 transition optimized at the intersection of one-shot and two-shot, so that the PC thickness of the edge of the INS film piece is 1.8-2.3 mm; S4, PC+ABS material thickness design, the thickness of PC+ABS material gradually transitions from 0.2 mm at the intersection of one-shot and two-shot to 1.2-1.5 mm at the edge position; S5, injection molding process control and optimization, S6, post-processing, through the thickness optimization of one-shot material and two-shot material, PC material is fully laid on the entire part surface and is compounded with the INS film piece, the thickness of PC material is 1:30 transition optimized at the intersection of one-shot and two-shot, the injection stress is reduced, the surface stress mark phenomenon of the double-color INS film piece can be effectively avoided, and the obtained INS film piece product has good appearance quality.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of double-color injection-molded INS film pieces, and particularly relates to a method for avoiding stress marks on the surface of double-color injection-molded INS parts. BACKGROUND

[0002] The double-color injection-molding technology can realize the fusion of two different colors or materials, so that the INS film piece has more rich colors and levels, and the appearance of the product is improved. The double-color injection-molded INS film piece usually comprises a plurality of layers, such as an outer light-transmitting plastic plate, an INS film piece, an inner light-transmitting plastic plate and a paint-sprayed light-shielding layer, and the layers are tightly combined through a precise injection-molding process. Different plastic materials with different properties, such as a combination of hard plastic and soft plastic, can be selected for the double-color injection-molding process, so that the physical properties of the part, such as wear resistance and impact resistance, are improved.

[0003] After retrieval, the patent with the application number CN202111278017.X discloses an automobile interior and exterior part of a double-color injection-molded intermediate INS film piece, which comprises, from top to bottom, an outer light-transmitting plastic plate, an INS film piece, an inner light-transmitting plastic plate and a paint-sprayed light-shielding layer. The INS film piece comprises a PMMA acrylic layer, an ink-printed light-transmitting layer and an ABS transparent substrate layer which are compounded from top to bottom. The bottom side of the INS film piece is integrally formed with the inner plastic plate through injection molding, and the top side of the INS film piece is integrally formed with the outer plastic plate through double-color injection molding. The paint-sprayed light-shielding layer is processed with a light-transmitting pattern for light to pass through and be visible. The light-transmitting pattern on the surface of the invention has high precision and will not be affected by the specific shape of the light-transmitting pattern due to the deformation of the product during the molding process. In addition, the inner and outer sides of the INS film piece are respectively provided with the inner and outer light-transmitting plastic plates, and the weather resistance is good.

[0004] In the current double-color injection-molding process of the INS film piece, the wall thickness of the second-shot material at the junction of the first-shot material and the second-shot material changes abruptly, as shown in the figure. After the second-shot injection, the INS film piece produces overall secondary shrinkage. The position of the double-color junction is affected by the shrinkage of the second-shot product, resulting in stress marks on the surface of the double-color INS film piece. Therefore, we need to propose a method for avoiding stress marks on the surface of double-color injection-molded INS parts. Figure 1 SUMMARY

[0005] The purpose of the application is to provide a method for avoiding stress marks on the surface of double-color injection-molded INS parts. Through the thickness optimization of the first-shot material and the second-shot material, the PC material covers the entire surface of the part and is combined with the INS film piece. At the junction of the first-shot and the second-shot, the thickness of the PC material is optimized by 1:30 transition, reducing the injection stress, which can effectively avoid the stress mark phenomenon on the surface of the double-color INS film piece, and the obtained INS film piece product has good appearance quality, thereby solving the problems raised in the background technology. ​

[0006] To achieve the above object, the present application provides the following technical scheme: a method for avoiding stress marks on the surface of a two-color injection-molded INS part, comprising the following steps:

[0007] S1, material preparation: selecting PC materials and PC+ABS materials with stable performance, and drying the PC materials to remove moisture in the PC materials and prevent bubbles and stress from being generated during injection molding;

[0008] S2, product preparation: selecting an INS part with appropriate size, shape, and function according to design requirements, and laying PC materials on the surface of the INS part;

[0009] S3, PC material thickness optimization: the thickness of the PC materials is designed to be 2.5-3 mm, and the thickness of the PC materials is optimized by 1:30 transition at the intersection of the first and second shots, so that the PC thickness at the edge of the INS diaphragm is 1.8-2.3 mm;

[0010] S4, PC+ABS material thickness design: the thickness of the PC+ABS materials gradually transitions from 0.2 mm at the intersection of the first and second shots to 1.2-1.5 mm at the edge position;

[0011] S5, injection molding process control and optimization: according to the characteristics of the PC materials and PC+ABS materials and the mold structure, appropriate injection molding temperature, injection molding pressure, injection molding speed, and holding time are set, and the injection molding parameters are monitored in real time during the injection molding process;

[0012] S6, post-processing: annealing treatment, surface treatment, and quality detection are performed on the injection-molded INS diaphragm.

[0013] Preferably, in step S1, the drying temperature of the PC materials is controlled between 80-100℃, the drying time of the PC materials is not less than 4 hours, the greater the humidity and thickness of the PC materials, the longer the drying time, and the humidity of the dried PC materials is less than 0.02%.

[0014] Preferably, in step S2, after the PC materials are combined with the INS diaphragm, a reasonable mold structure is designed and selected, including a runner, a gate, and an exhaust system, so that the PC materials and PC+ABS materials are uniformly and quickly filled into the mold cavity, and the mold temperature distribution is uniform to avoid stress problems caused by local overheating or overcooling.

[0015] Preferably, in step S3, the PC materials include a main body part combined at the middle position of the INS diaphragm and an edge part combined at the edge position of the INS diaphragm;

[0016] The thickness of the main body part is 2.5-3 mm, which is used to provide sufficient strength and stability.

[0017] The thickness of the edge part is 1.8-2.3mm, which ensures the strength and aesthetics of the edge position of the INS diaphragm.

[0018] Preferably, in step S4, the PC material is gradually transitioned at a ratio of 1:30, i.e. from a 3mm area of the first shot to a 0.2mm area of the second shot, and the PC+ABS material is used as the second shot material, and the thickness of the second shot material gradually transitions from 0.2mm at the junction to 1.2-1.5mm at the edge, which helps the PC material and the PC+ABS material to be well combined at the junction of the first and second shots, and reduces stress marks.

[0019] Preferably, in step S5, the injection temperature of the PC material is controlled between 250-300℃, and the injection temperature of the PC+ABS material is controlled between 240-280℃;

[0020] The injection pressure value is adjusted so that the PC material and the PC+ABS material melt sufficiently fills the mold cavity, and the injection pressure is gradually increased during the injection process until the plastic material melt is stably discharged;

[0021] The injection speed is adjusted, the injection speed is slowed down when the plastic material melt passes through the gate, high-speed injection is used during the filling process, and the speed is slowed down at the end of the filling;

[0022] The INS diaphragm is fully cured and the shrinkage deformation is reduced through the holding pressure treatment, the mold applies a stable holding pressure to the plastic material, which prevents the INS diaphragm from sinking or changing in size.

[0023] Preferably, when monitoring the injection parameters in real time, the monitoring equipment on the injection molding machine is used to observe the parameter changes of the injection pressure, injection temperature, and injection speed in real time during the injection process, and the exhaust condition of the mold is checked regularly to ensure that the air passage is unobstructed and to avoid the generation of bubbles and stress marks; when abnormal conditions are found during the injection process, the machine is immediately stopped for inspection of the injection parameters.

[0024] Preferably, in step S6, annealing treatment: through the heating and cooling process, the residual stress inside the INS diaphragm is released, and the stress marks and deformation are reduced, and the specific process is as follows:

[0025] The injected INS diaphragm is placed in an annealing furnace, heated to a temperature lower than the glass transition temperature of the PC material and the PC+ABS material, and kept for a period of time to release the stress inside the INS diaphragm, and then slowly cooled to room temperature to avoid thermal stress caused by rapid cooling.

[0026] Preferably, the surface treatment includes:

[0027] Polishing: using polishing tools and polishing agents to polish the side edges of the INS film, removing burrs, flash and surface defects generated during the injection molding process;

[0028] Cleaning: using cleaning agents to clean the surface of the INS film, removing oil stains, dust and other impurities, ensuring that the surface of the INS film is clean and flawless.

[0029] Preferably, the quality detection includes:

[0030] Appearance detection: using naked eyes to inspect the appearance of the INS film, checking whether the INS film has obvious defects, including cracks, bubbles, depressions, uneven color and stress marks;

[0031] Size measurement: using precise measurement tools to measure the size of the INS film through sampling inspection, to check whether the size of the INS film meets the design requirements and tolerance requirements, and to evaluate the size consistency of the same batch of INS films;

[0032] Material performance test: detecting the melting point, strength, hardness and toughness of the INS film, to evaluate the durability and reliability of the INS film.

[0033] Compared with the prior art, the beneficial effects of the present application are:

[0034] The present application optimizes the thickness of the first and second materials, PC material covers the entire surface of the part and is compounded with the INS film, and at the interface of the first and second materials, the thickness of the PC material is 1:30 transition optimized, reducing the injection stress, which can effectively avoid the stress mark phenomenon on the surface of the double-color INS film, and the obtained INS film product has good appearance quality. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a sectional view of the prior art INS film;

[0036] Figure 2 is a sectional view of the INS film prepared by the present application;

[0037] Figure 3 is a flowchart of the present application.

[0038] In the figure: 1, INS film; 2, PC material; 3, PC+ABS material; 4, light guide lamp plate; 5, light shielding substrate. DETAILED DESCRIPTION

[0039] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0040] Please refer to Figure 2-3 The present application provides a technical solution: a method for avoiding stress marks on the surface of a double-color injection-molded INS part, comprising the following steps:

[0041] S1, material preparation: selecting PC material 2 and PC+ABS material 3 with stable performance, and drying the PC material 2 to remove moisture in the PC material 2 and prevent bubbles and stress from being generated during injection molding;

[0042] In step S1, when the PC material 2 is dried, the drying temperature is controlled between 80-100℃, and the drying time of the PC material 2 is not less than 4 hours. The greater the humidity and thickness of the PC material 2, the longer the drying time. The humidity of the dried PC material 2 is less than 0.02%.

[0043] S2, product preparation: selecting an INS part with appropriate size, shape and function according to design requirements, and laying the PC material on the surface of the INS part;

[0044] The INS film includes a light guide lamp plate 4, one side of the light guide lamp plate 4 is provided with a light-shielding substrate 5, and the other side of the light guide lamp plate 4 is provided with an INS film 1, and the INS film 1 is attached with PC material 2 and PC+ABS material 3 injected by a double-color injection molding process.

[0045] During the product design stage, special attention is paid to the areas that may generate stress marks. For example, sharp corners and sharp thickness changes are avoided to reduce stress concentration.

[0046] In step S2, after the PC material 2 is combined with the INS film, a reasonable mold structure is designed and selected, including a flow channel, a gate and an exhaust system, so that the PC material 2 and the PC+ABS material 3 are uniformly and quickly filled into the mold cavity, and the mold temperature distribution is uniform to avoid stress problems caused by local overheating or overcooling.

[0047] Ensure that the gate size is moderate and uniformly distributed to avoid insufficient filling caused by too small or too few gates, and increase the cold well or overflow groove to improve the filling effect;

[0048] Design a balanced mold temperature control system to ensure uniform mold temperature and avoid local overheating. Install water wells in the mold or use 3D-printed conformal water channels to address uneven mold temperature.

[0049] The plastic injection mold runner and cavity should be designed with a good exhaust system to reduce the stress and pressure in the mold cavity. More exhaust holes should be opened around the mold to ensure that the gas in the mold cavity is smoothly discharged during injection.

[0050] Ensure that the moving parts (such as lifters, sliders, etc.) are tightly fitted to avoid looseness that may cause the mold temperature to rise. Optimize the water channel configuration to ensure good cooling effect.

[0051] S3. PC material 2 thickness optimization: The thickness of PC material 2 is designed to be 2.5-3mm, and at the junction of the first shot and the second shot, the thickness of PC material 2 is optimized by a transition ratio of 1:30, so that the PC thickness at the edge of the INS diaphragm is 1.8-2.3mm;

[0052] In step S3, the PC material 2 includes a main body portion compounded at the middle position of the INS diaphragm and an edge portion compounded at the edge position of the INS diaphragm;

[0053] The thickness of the main body is 2.5-3 mm to provide sufficient strength and stability;

[0054] The thickness of the edge portion is 1.8 to 2.3 mm to ensure the strength and aesthetics of the INS diaphragm edge. The thickness of the edge portion should not be too thin to prevent shrinkage deformation and stress marks during the injection molding process.

[0055] Reasonable exhaust grooves can be designed in the mold to ensure that gas can be discharged smoothly during the injection molding process, reducing the generation of bubbles and stress marks.

[0056] S4. Thickness design of PC+ABS material 3: The thickness of PC+ABS material 3 gradually transitions from 0.2mm at the junction of the first and second shots to 1.2-1.5mm at the edge to reduce stress concentration;

[0057] In step S4, PC material 2 adopts a smooth transition ratio of 1:30, that is, transitioning from the 3mm area of ​​the first shot to the 0.2mm area of ​​the second shot. PC+ABS material 3 is used as the second shot material, and the thickness of the second shot material gradually transitions from 0.2mm at the intersection to 1.2-1.5mm at the edge, which helps PC material 2 and PC+ABS material 3 to be well combined at the intersection of the first shot and the second shot, and reduces stress marks.

[0058] S5. Injection molding process control and optimization: According to the characteristics of PC material 2 and PC+ABS material 3 and the mold structure, set the appropriate injection temperature, injection pressure, injection speed and holding time, and monitor the injection molding parameters in real time during the injection molding process;

[0059] In step S5, the injection temperature of PC material 2 is controlled between 250-300℃, and the injection temperature of PC+ABS material 3 is controlled between 240-280℃;

[0060] The injection pressure value is adjusted so that the PC material 2 and PC+ABS material 3 melt sufficiently fills the mold cavity, and the injection pressure is gradually increased during the injection process until the plastic material melt is stably discharged;

[0061] The injection speed is adjusted, the injection speed is slowed down when the plastic material melt passes through the gate, high-speed injection is used during the mold filling process, and the speed is slowed down at the end of the mold filling;

[0062] The INS film is fully cured by the holding pressure process, and the shrinkage deformation is reduced, the mold applies stable holding pressure to the plastic material, and the INS film is prevented from sinking or changing in size.

[0063] The holding pressure and time are reasonably set to avoid the generation of stress marks caused by excessive or insufficient holding pressure, and the injection pressure is reduced to reduce the stress during the filling process;

[0064] The material temperature, back pressure and screw speed are appropriately increased, if necessary, local heating of the mold can be performed by using electric heating rods or adding water channels to run high temperature hot oil, etc. to improve the stress marks.

[0065] When monitoring the injection parameters in real time, the monitoring equipment on the injection molding machine is used to observe the parameter changes of injection pressure, injection temperature and injection speed in real time during the injection process, and the exhaust condition of the mold is checked regularly to ensure that the gas path is unobstructed and avoid the generation of bubbles and stress marks; when abnormal conditions are found during the injection process, stop immediately and check the injection parameters.

[0066] The opening and closing state of the mold is monitored in real time to ensure that the mold is opened and closed at the correct time;

[0067] Check if the mold is damaged or abnormal, such as broken ejector pins, loose inserts, etc., to prevent further damage to the mold;

[0068] Monitor the cleanliness and lubrication of the mold to ensure normal operation of the mold;

[0069] Real-time monitoring of various parameters of the injection molding machine, such as pressure, temperature, speed, etc., to ensure that these parameters fluctuate within the set range;

[0070] Monitor the clamping force during the injection process to ensure that the mold is tightly locked during the injection process to prevent the mold from being opened;

[0071] Monitor the appearance quality of the injection molded product by visual inspection and other technical means, such as burrs, material defects, deformation, etc.

[0072] Monitor the dimensional accuracy of the product to ensure that it meets the design requirements.

[0073] The above monitoring process can be achieved by using mold monitors, sensor technology, or machine vision technology.

[0074] S6, post-processing: annealing, surface treatment and quality detection of injection molded INS diaphragm.

[0075] In step S6, annealing: through heating and cooling process, release the residual stress inside the INS diaphragm, reduce stress marks and deformation, the specific process is:

[0076] Put the injection molded INS diaphragm in the annealing furnace, heat it to below the glass transition temperature of PC material 2 and PC+ABS material 3, and keep it for a period of time, so that the stress inside the INS diaphragm is released, and then slowly cool it to room temperature to avoid thermal stress caused by rapid cooling.

[0077] Surface treatment includes:

[0078] Polishing: use polishing tools and polishing agents to polish and polish the side edges of the INS diaphragm, remove burrs, flash and surface defects generated during injection molding;

[0079] Cleaning: use cleaning agent to clean the surface of INS diaphragm, remove oil stains, dust and other impurities, ensure the surface of INS diaphragm clean and flawless.

[0080] Quality detection includes:

[0081] Appearance detection: use naked eye to check the appearance of INS diaphragm, check whether there are obvious defects in INS diaphragm, defects include cracks, bubbles, concave, uneven color and stress marks;

[0082] Dimension measurement: use precise measurement tools to measure the size of INS diaphragm by sampling inspection, to evaluate the size consistency of INS diaphragm in the same batch;

[0083] Material performance test: test the melting point, strength, hardness and toughness of INS diaphragm, evaluate the durability and reliability of INS diaphragm.

[0084] Also includes functional test:

[0085] Pressure test: pressure test on parts that need to bear pressure to verify their performance under pressure, which helps to evaluate the sealing, pressure resistance and structural strength of the parts;

[0086] Fluid testing: Fluid testing is performed on parts that require contact with fluids to verify their performance in a fluid environment, which helps to assess the corrosion resistance, sealing, and fluid resistance of the parts, among other characteristics.

[0087] Wear resistance testing: Wear resistance testing is performed on parts that need to withstand wear to verify their wear resistance during use, which helps to assess the service life and reliability of the parts.

[0088] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements, and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method of avoiding surface stress marks on a two-color injection molded (INS) part, characterized by: The method comprises the following steps: S1, material preparation: selecting PC materials and PC+ABS materials with stable performance, and drying the PC materials to remove moisture in the PC materials to prevent bubbles and stress from being generated in the injection molding process; S2, product preparation: selecting INS parts with appropriate size, shape and function according to design requirements, and laying PC materials on the surface of the INS parts; S3, PC material thickness optimization: the thickness of the PC material is designed to be 2.5-3mm, and the thickness of the PC material is optimized by 1:30 transition at the intersection of the first and second shots, so that the thickness of the PC at the edge of the INS film is 1.8-2.3mm; S4, PC+ABS material thickness design: the thickness of the PC+ABS material gradually transitions from 0.2mm at the intersection of the first and second shots to 1.2-1.5mm at the edge position; S5, injection molding process control and optimization: according to the characteristics of the PC material and the PC+ABS material and the mold structure, the appropriate injection temperature, injection pressure, injection speed and holding time are set, and the injection parameters are monitored in real time during the injection process; S6, post-processing: annealing treatment, surface treatment and quality detection are performed on the injection molded INS film.

2. The method of avoiding stress marks on the surface of a two-color injection molded INS part of claim 1, wherein: In step S1, when the PC material is dried, the drying temperature is controlled between 80-100℃, the drying time of the PC material is not less than 4 hours, the greater the humidity and thickness of the PC material, the longer the drying time, and the humidity of the dried PC material is less than 0.02%.

3. The method of avoiding stress marks on the surface of a two-color injection molded INS part of claim 1, wherein: In step S2, after the PC material is combined with the INS film, a reasonable mold structure including a runner, a gate and an exhaust system is designed and selected, so that the PC material and PC+ABS material melt uniformly and quickly fills the mold cavity, and the mold temperature distribution is uniform to avoid stress problems caused by local overheating or overcooling.

4. The method of avoiding stress marks on the surface of a two-color injection molded INS part of claim 1, wherein: In step S3, the PC material includes a main body part combined at the middle position of the INS film and an edge part combined at the edge position of the INS film; The thickness of the main body part is 2.5-3mm, which is used to provide sufficient strength and stability; The thickness of the edge part is 1.8-2.3mm, which ensures the strength and aesthetics of the edge position of the INS film.

5. The method of avoiding stress marks on the surface of a two-color injection molded INS part of claim 1, wherein: In step S4, the PC material is gradually transitioned by 1:30 ratio, i.e. from 3mm area of the first shot to 0.2mm area of the second shot, and the PC+ABS material is used as the second shot material, which is gradually transitioned from 0.2mm at the intersection to 1.2-1.5mm at the edge, which helps the PC material and PC+ABS material to be well combined at the intersection of the first and second shots and reduces stress marks.

6. The method of avoiding surface stress marks on a two-color injection molded INS part of claim 1, wherein: In step S5, the injection temperature of the PC material is controlled between 250-300℃, and the injection temperature of the PC+ABS material is controlled between 240-280℃; The injection pressure value is adjusted so that the PC material and PC+ABS material melt fills the mold cavity, and the injection pressure is gradually increased during the injection process until the plastic material melt is stably discharged; Adjusting the injection speed, slowing down the injection speed when the plastic material solution passes through the gate, using high-speed injection during the mold filling process, and slowing down the speed at the end of the mold filling process; Through the holding pressure process, the INS diaphragm is fully cured and the shrinkage deformation is reduced. The mold applies stable holding pressure to the plastic material to prevent the INS diaphragm from sagging or changing in size.

7. A method of avoiding surface stress marks on a two-color injection molded INS part according to claim 6, characterized in that: When monitoring the injection molding parameters in real time, use the monitoring equipment on the injection molding machine to observe the changes in injection pressure, injection temperature, and injection speed during the injection molding process in real time, and periodically check the exhaust condition of the mold to ensure that the air path is unobstructed and avoid the formation of bubbles and stress marks. When abnormal conditions are found during the injection molding process, stop immediately and check the injection molding parameters.

8. The method of avoiding surface stress marks on a two-color injection molded INS part of claim 1, wherein: In step S6, annealing treatment: through the heating and cooling process, the residual stress inside the INS diaphragm is released, and the stress marks and deformation are reduced. The specific process is as follows: Place the injection-molded INS diaphragm in the annealing furnace, heat it to a temperature lower than the glass transition temperature of PC material and PC+ABS material, and keep it for a period of time to release the stress inside the INS diaphragm. Slowly cool to room temperature to avoid thermal stress caused by rapid cooling.

9. The method of avoiding surface stress marks on a two-color injection molded INS part of claim 1, wherein, Surface treatment includes: Polishing: use polishing tools and polishing agents to polish and polish the side edges of the INS diaphragm, remove burrs, flash and surface defects generated during the injection molding process; Cleaning: use cleaning agents to clean the surface of the INS diaphragm to remove oil stains, dust and other impurities, and ensure that the surface of the INS diaphragm is clean and flawless.

10. The method of avoiding stress marks on the surface of a two-color injection molded INS part of claim 1, wherein, Quality detection includes: Visual inspection: visually inspect the appearance of the INS diaphragm to check for obvious defects, including cracks, bubbles, sagging, uneven color, and stress marks; Dimensional measurement: use precision measurement tools to measure the dimensions of the INS diaphragm through sampling inspection to determine whether the dimensions meet the design requirements and tolerance requirements, and evaluate the dimensional consistency of the same batch of INS diaphragms; Material performance testing: test the melting point, strength, hardness, and toughness of the INS diaphragm to evaluate its durability and reliability.

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