Injection molding deformation compensation method and automobile weather strip injection molding method

Abstract

This invention discloses a deformation compensation method for injection molding and a method for injection molding automotive water deflectors. The method includes: analyzing the deformation of the product after injection molding and obtaining deformation data; based on the distance between the starting position and the position of maximum deformation and the deformation amount at the position of maximum deformation, taking the starting position as the origin, obtaining the deformation deflection angle of the product at the position of maximum deformation relative to its initial state; setting a deformation compensation angle based on the obtained deformation deflection angle; and deflecting the designed product by the set deformation compensation angle from the starting position of deformation in the opposite direction of product deformation to obtain a compensated product design model. This invention effectively solves the warpage deformation problem of products during injection molding, ensuring that the injection-molded exterior parts meet product quality requirements.

Description

Technical Field

[0001] This invention belongs to the field of injection molding technology, specifically relating to an injection molding deformation compensation method and an injection molding method for automotive water deflectors. Background Technology

[0002] As people's demands for the quality of car exteriors increase, higher requirements are being placed on the quality and manufacturing processes of automotive interior components. The A-pillar, a key exterior component of a car, is located in the most visible area to the user, and its assembly quality has a significant impact on the overall appearance of the vehicle. (Refer to...) Figure 1 and 2 A water deflector strip 1 is installed on the outer pillar 2 of car A. When the existing water deflector strip products are formed, there is often warping and deformation at the tip of the water deflector strip, which makes it difficult to meet the design requirements for the gap surface difference at the tip of the water deflector strip. Mouse holes (holes caused by poor assembly) are easy to appear at the tip position. Furthermore, assembly gaps are also easy to appear at the joint position of the sealing skirt 6 and the sheet metal part 3 around the perimeter, thus affecting the assembly appearance quality of the outer pillar of car A. Summary of the Invention

[0003] The purpose of this invention is to provide a method for compensating for deformation during injection molding and a method for injection molding automotive water deflectors, so as to solve the assembly quality problem caused by deformation of the water deflector after injection molding.

[0004] This invention is achieved through the following technical solution:

[0005] Injection molding deformation compensation methods include:

[0006] S01. Analyze the deformation of the product after injection molding and obtain the deformation data of the product.

[0007] S02. Based on the deformation data, obtain the starting position where deformation begins on the product, the position with the largest deformation, and the deformation amount at the position with the largest deformation.

[0008] S03. Based on the distance between the starting position of deformation and the position of maximum deformation and the deformation at the position of maximum deformation, take the starting position of deformation as the origin and obtain the deformation deflection angle of the product at the position of maximum deformation relative to its initial state.

[0009] S04. Based on the obtained deformation deflection angle, set the deformation compensation angle. Starting from the starting position of the deformation, deflect the designed product in the opposite direction of the product deformation by the set deformation compensation angle to obtain the compensated product design model.

[0010] In some embodiments, in step S01, the deformation data is the product deformation data when the product deformation is at its minimum.

[0011] In some embodiments, the injection molding process parameters corresponding to the minimum product deformation are obtained, and the product is injection molded using the injection molding process parameters and the compensated product design model.

[0012] In some embodiments, the effects of deformation caused by cooling, deformation caused by volume shrinkage, and deformation caused by material molecular alignment on product deformation are analyzed, and injection molding process parameters are optimized to obtain the injection molding process parameters corresponding to the minimum product deformation.

[0013] In some embodiments, a size gradient transition zone is provided in the area where the product is deformed, from the starting position of deformation toward the side with the largest deformation, wherein the ratio between the length of the size gradient transition zone and the size difference of the size gradient transition zone in the deformation direction is not less than 30.

[0014] On the other hand, the present invention also provides a method for injection molding a water deflector strip for automobiles, wherein the water deflector strip is injection molded using a two-color injection molding process, and the method includes the following steps:

[0015] Using the aforementioned injection molding deformation compensation method, compensation designs were performed on both hard and soft rubber products of the water-blocking strip, resulting in the compensated design models of the hard and soft rubber products and the corresponding injection molding process parameters.

[0016] Based on the compensated hard rubber product design model, soft rubber product design model, and corresponding injection molding process parameters, the water-blocking strip is subjected to two-color injection molding.

[0017] In some embodiments, the injection molding process parameters are the parameters corresponding to the minimum deformation of hard rubber products and soft rubber products.

[0018] In some embodiments, the material of the hard rubber product is PP+30%GF; the material of the soft rubber product is TPE.

[0019] In some embodiments, the injection molding process parameters for the rigid plastic product are as follows: the number of injection gates is set to 3, and the holding pressure is set to 80% of the maximum injection pressure.

[0020] In some embodiments, the injection molding process parameters for the soft rubber product are as follows: the number of injection gates is set to 4, and the holding pressure is set to 80% of the maximum injection pressure.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] This invention pre-compensates the product design by obtaining the amount of warpage deformation of the product under corresponding injection molding process parameters, and then uses the pre-compensated product design model and corresponding injection molding process parameters to perform injection molding of the product. This can effectively solve the warpage deformation problem of the product during injection molding, and enable the injection-molded exterior parts to meet the product quality requirements.

[0023] This method can be widely applied to automotive injection molded parts that are prone to warping and deformation, avoiding mold repair, improving production yield, and enhancing the assembly quality of automotive products. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram showing the assembly status of a car's water deflector.

[0026] Figure 2 for Figure 1 Schematic diagram of the AA-direction section.

[0027] Figure 3 This is a schematic diagram of the deformation compensation principle in the method of the present invention.

[0028] Figure 4 This is a schematic diagram of the size gradient transition zone structure in the method of the present invention.

[0029] Figure 5 This is a schematic diagram of the deformation of the automotive water deflector in the Z direction, as analyzed by CAE.

[0030] Figure 6 This is a partial schematic diagram of the deformation of the automotive water deflector in the Z direction, as analyzed by CAE.

[0031] Figure 7 This is a schematic diagram showing the difference between the soft rubber product for automotive water deflectors before and after deformation according to the present invention.

[0032] Figure 8 This is a schematic diagram showing the difference between the hard rubber product of the car water deflector before and after deformation according to the present invention.

[0033] Figure 9 This is a schematic diagram of the deformation compensation for the water deflector strip of an automobile according to the present invention.

[0034] in:

[0035] 1. Water barrier strip; 2. External column; 3. Sheet metal parts;

[0036] 4. Soft rubber products; 5. Hard rubber products; 6. Sealing skirts;

[0037] 8. Soft rubber product before deformation; 9. Soft rubber product after deformation; 10. Hard rubber product before deformation; 11. Hard rubber product after deformation.

[0038] 12. Gradual transition zone in size;

[0039] α, Deformation deflection angle; β, Deformation compensation angle. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0041] This invention relates to a deformation compensation method for injection molding, used for designing injection molding models and injection molding process schemes for automotive exterior parts such as water deflectors. By obtaining the amount of deformation that causes warping deformation of the product under corresponding injection molding process parameters, the product design is pre-compensated. Then, the pre-compensated product design model and corresponding injection molding process parameters are used to perform injection molding of the product, thereby solving the problem of warping deformation of the product during injection molding and ensuring that the injection-molded exterior parts meet product quality requirements.

[0042] In one embodiment, reference is made to Figure 3 The method for compensating for deformation during injection molding includes the following steps:

[0043] S01. Analyze the deformation of the product after injection molding and obtain the deformation data of the product. The deformation data here includes the starting position of deformation, the position with the largest deformation, and the deformation amount at the position with the largest deformation. The product deformation can be analyzed by CAE analysis software for product simulation analysis.

[0044] S02. Based on the deformation data, obtain the starting position where deformation begins on the product, the position with the largest deformation, and the deformation amount at the position with the largest deformation.

[0045] S03. Based on the distance between the starting position of deformation and the position of maximum deformation, and the deformation at the position of maximum deformation, take the starting position of deformation as the origin and obtain the deformation deflection angle α of the product at the position of maximum deformation relative to its initial state; here, the initial state refers to the initial state of the injection molded product before deformation.

[0046] S04. Based on the obtained deformation deflection angle, set the deformation compensation angle β. Starting from the initial position of deformation, deflect the designed product in the opposite direction of the product deformation by the set deformation compensation angle β, obtaining the compensated product design model. The deformation compensation angle set here is obtained by multiplying the deformation deflection angle by a correction coefficient, which is generally taken as 0.5-0.8. Furthermore, by analyzing the influence of different injection molding process parameters on product warpage, a correspondence between the correction coefficient and the injection molding process parameters can be established. This allows for obtaining the corresponding correction coefficient based on the injection molding process parameters used during injection molding, enabling more accurate compensation of the product design model.

[0047] At this point, the mold is designed based on the compensated product design model. Combined with the product injection molding process parameters corresponding to the deformation data obtained in step S01, the product is injection molded. Since the product obtained by injection molding has undergone pre-compensation design in the opposite direction of its deformation, the product obtained by injection molding can ultimately meet the requirements of the product design index after deformation.

[0048] In one embodiment, in step S01, the deformation data refers to the product deformation data when the deformation amount is minimal. By obtaining the deformation data when the product deformation amount is minimal, the product design model based on the obtained deformation compensation design can better guarantee the injection molding quality of the product.

[0049] In one embodiment, the injection molding process parameters corresponding to the minimum product deformation are obtained, and the product is injection molded using the injection molding process parameters and the compensated product design model.

[0050] In one embodiment, the effects of deformation caused by cooling, volume shrinkage, and molecular alignment during product injection molding are analyzed. Based on the analysis, injection molding process parameters are optimized to obtain the injection molding process parameters that minimize product deformation. This reduces the time required for optimizing injection molding process parameters and improves product development efficiency. Based on the optimized injection molding process parameters, the amount of deformation of the injection-molded product is controlled. When pre-compensating the product design model under this condition, the product injection molding deformation can be more precisely controlled. At this point, based on the compensated product design model and injection molding process parameters, it can be ensured that the quality of the injection-molded product meets the design requirements even after warping deformation.

[0051] In one embodiment, a size gradient transition zone is provided in the deformation area of ​​the product from the starting position of deformation toward the position of maximum deformation, and the ratio between the length of the size gradient transition zone and the size difference of the size gradient transition zone in the deformation direction is not less than 30.

[0052] Reference Figure 4 As shown, the length of the dimensional gradient transition zone 12 is L, and the difference in product dimensions in the deformation direction (such as the difference between the maximum and minimum thickness values ​​of the product in this dimensional gradient transition zone) is T. The ratio between the two is called the smooth transition ratio, which is set to be no less than 30. By setting the dimensional gradient transition zone and its length, the dimensional accuracy of the product after injection molding can be further improved, resulting in better appearance quality. This effectively compensates for deformation caused by uneven material molecular alignment.

[0053] The water deflector strip of the exterior pillar of a car is usually made using a two-color injection molding process (i.e., a two-material injection molding process). This process uses a rotating injection mold to drive the moving mold part of the mold to rotate. Through one set of molds, products containing two materials can be produced in one process.

[0054] During injection molding, the first shot injects hard plastic to obtain hard plastic product 5, and the second shot injects soft plastic onto the hard plastic product to obtain soft plastic product 4, thus obtaining a two-color injection molded product.

[0055] When molding water deflectors, the hard plastic is generally made of PP + 30%GF, with an elastic modulus of about 4000 MPa, which can provide a certain rigidity for the product. PP + 30%GF is prone to appearance defects such as floating fibers and flow marks during injection molding. Therefore, a layer of soft plastic is usually injected onto the outside of the molded hard plastic product. The soft plastic is generally made of TPE material, with an elastic modulus of generally less than 100 MPa, which can cover the appearance defects of the hard plastic product. At the same time, the low modulus and low interference of the soft plastic can provide a sealing effect to prevent water from entering the windshield.

[0056] Furthermore, since PP+30%GF is an anisotropic material, it is prone to warping and deformation after injection molding, which can cause the entire product to deform and affect the assembly appearance quality of the product.

[0057] To address the above problems, the present invention provides an injection molding method for automotive water deflectors, wherein the water deflector is injection molded using a two-color injection molding process. This injection molding method includes the following steps:

[0058] Using the injection molding deformation compensation method in the above embodiments, compensation design is performed on the hard rubber product and the soft rubber product of the water barrier strip respectively, and the design model of the compensated hard rubber product, the design model of the soft rubber product and the corresponding injection molding process parameters (injection molding process parameters of hard rubber product and injection molding process parameters of soft rubber product) are obtained.

[0059] Based on the compensated hard rubber product design model, soft rubber product design model and corresponding injection molding process parameters, the water-blocking strip is subjected to two-color injection molding. The specific two-color injection molding method adopts the existing method, and no specific limitation is made here.

[0060] In one embodiment, the injection molding process parameters are those corresponding to the minimum deformation of the hard and soft rubber products, in order to further improve the quality of the products obtained by injection molding.

[0061] Reference Figure 5 and Figure 6 Based on CAE analysis, the deformation of the water barrier strip in the Z direction after injection molding is analyzed, and deformation data such as the starting position of the deformation of the water barrier strip in the Z direction and the amount of deformation at each position can be obtained.

[0062] Reference Figure 7 and Figure 8 The deformation of hard rubber products and soft rubber products was analyzed, such as... Figure 7 This is a schematic diagram showing the soft rubber product of the water-retaining strip before and after deformation. Figure 8 This is a schematic diagram of the water-blocking strip hardware product before and after deformation.

[0063] Analysis of the causes of warping and deformation of water-retaining strips during injection molding:

[0064] The main reasons for warping and deformation of injection molded products are as follows: 1) uneven shrinkage, 2) uneven temperature, 3) uneven material molecular orientation, and 4) corner effect. Uneven shrinkage refers to the difference in shrinkage between different areas of the product, leading to product deformation; uneven temperature refers to the temperature difference between the upper and lower surfaces of the product, leading to product deformation; uneven material molecular orientation refers to the difference in fiber or molecular orientation, leading to product deformation; and the corner effect refers to the effect of heat accumulation at the corners of the product, resulting in differences in shrinkage between the inner and outer surfaces of the corners, leading to product deformation.

[0065] To address the deformation caused by cooling during injection molding, the cooling water temperature of the moving mold / stationary mold can be optimized to obtain an optimized injection molding process.

[0066] To address the deformation caused by volume shrinkage during injection molding, the holding time, holding pressure, product structure, number of gates, and gate type can be optimized to obtain an optimized injection molding process.

[0067] To address the deformation caused by the orientation of material molecules during injection molding, the holding time, holding pressure, product structure, number of gates, and gate type can be optimized to obtain an optimized injection molding process.

[0068] For the PP+30%GF material used in the rigid plastic, the best optimization method to solve the warping deformation problem caused by uneven molecular orientation is to change the gate position so that the glass fibers can be oriented in one direction. However, since the water-blocking strip is a slender strip part, in order to ensure the quality of injection molding, the injection molding scheme is optimized by improving the number of gates.

[0069] Taking rigid plastic products as an example, three injection gates are set up. Injection and filling proceed sequentially from the middle to both sides. That is, the middle injection gate is opened first, and when the injection reaches the positions of the two side injection gates, the two side injection gates are opened to achieve injection molding of the rigid plastic product. Using this injection molding method can not only avoid the formation of weld lines, but also, to a certain extent, allow the glass fiber to be oriented along the length of the part.

[0070] Specifically, in this embodiment, the injection molding process parameters for hard rubber products are: holding time of 5 seconds, number of injection gates set to 3, and holding pressure set to 80% of the maximum injection pressure (30 MPa); the injection molding process parameters for soft rubber products are: holding time of 5 seconds, number of injection gates set to 4, and holding pressure set to 80% of the maximum injection pressure (20 MPa). Simultaneously, the diameter of the cooling water channels can be increased, and the spacing between the cooling water channels can be decreased, such as setting the diameter of the cooling water channels to 12 mm and the spacing between the cooling water channels to 80 mm, to improve product warpage.

[0071] by Figure 9 Taking the aforementioned water deflector product as an example, CAE analysis revealed a deformation of 2.5mm at the end, corresponding to a deflection angle of 4°. Pre-deformation compensation was applied to the product design model based on the mold-making data, with a correction factor of 0.5, resulting in a compensation value of 2° for the product design model. Based on the compensated product design model, mold design and manufacturing were carried out. After trial molding, the clearance fit between the water deflector product and the body sheet metal parts was 0, meeting the assembly standard requirements of the body.

[0072] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0073] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this invention does not imply that the components are required to be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0074] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for injection molding automotive water deflectors, characterized in that, The water-blocking strip is injection molded using a two-color injection molding process, and the method includes the following steps: The deformation compensation method of injection molding was adopted to compensate for the hard rubber product and soft rubber product of the water barrier strip respectively, and the design models of the compensated hard rubber product and soft rubber product and the corresponding injection molding process parameters were obtained. Based on the compensated hard rubber product design model, soft rubber product design model and corresponding injection molding process parameters, the water-blocking strip is subjected to two-color injection molding. Injection molding deformation compensation methods include: S01. Analyze the deformation of the product after injection molding and obtain the deformation data of the product. S02. Based on the deformation data, obtain the starting position where deformation begins on the product, the position with the largest deformation, and the deformation amount at the position with the largest deformation. S03. Based on the distance between the starting position of deformation and the position of maximum deformation and the deformation at the position of maximum deformation, take the starting position of deformation as the origin and obtain the deformation deflection angle of the product at the position of maximum deformation relative to its initial state. S04. Based on the obtained deformation deflection angle, set the deformation compensation angle. Starting from the starting position of the deformation, deflect the designed product in the opposite direction of the product deformation by the set deformation compensation angle to obtain the compensated product design model. From the starting position of deformation toward the side with the largest deformation, a size gradient transition zone is set in the area where deformation occurs on the product. The ratio between the length of the size gradient transition zone and the size difference of the size gradient transition zone in the deformation direction is not less than 30. The material of the rigid plastic product is PP+30%GF; the injection molding process parameters of the rigid plastic product are: the number of injection gates is set to 3, and the holding pressure is set to 80% of the maximum injection pressure; when the rigid plastic product is injected, it is injected and filled sequentially from the middle to both sides. The middle injection gate is opened first. When the injection fills to the position of the two injection gates on both sides, the two injection gates on both sides are opened to make the glass fiber oriented along the length of the part.

2. The injection molding method for automotive water deflectors according to claim 1, characterized in that, In step S01, the deformation data is the product deformation data when the product deformation is at its minimum.

3. The injection molding method for automotive water deflectors according to claim 2, characterized in that, Obtain the injection molding process parameters corresponding to the minimum product deformation, and use the injection molding process parameters and the compensated product design model to perform injection molding on the product.

4. The injection molding method for automotive water deflectors according to claim 2, characterized in that, The effects of deformation caused by cooling, volume shrinkage, and molecular alignment on product deformation are analyzed. Injection molding process parameters are optimized to obtain the injection molding process parameters that minimize product deformation.

5. The injection molding method for automotive water deflectors according to claim 1, characterized in that, The injection molding process parameters are those corresponding to the minimum deformation of hard and soft rubber products.

6. The injection molding method for automotive water deflectors according to claim 1, characterized in that, The material of the soft rubber product is TPE.

7. The injection molding method for automotive water deflectors according to claim 6, characterized in that, The injection molding process parameters for the soft rubber product are as follows: the number of injection gates is set to 4, and the holding pressure is set to 80% of the maximum injection pressure.

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