Moldflow-based warp prevention production method and long strip injection molding production method

Abstract

The application discloses a warping prevention production method based on Moldflow, which comprises the following steps: firstly, obtaining and optimizing a theoretical deformation amount by automatically measuring and calculating through simulation analysis of Moldflow, so as to obtain a warping pre-deformation amount; then, establishing standard parameters of a pressure maintaining time and a pressure maintaining pressure according to the warping value of different pressure maintaining parameters through the pre-deformation amount; and finally, performing trial molding and mold repairing according to the pre-deformation amount and the standard pressure maintaining parameters until the molding size of the product meets the requirements, so that mass production can be realized. The warping prevention production method based on Moldflow simulation analysis determines the pre-deformation amount of the mold and the standard parameters of the pressure maintaining process in sequence, reduces the number of mold repairing, reduces the mold repairing cost, reduces the cost of early development investment, and improves the quality and efficiency of production development. The application further discloses a long strip injection molding part production method, which optimizes the above warping prevention production method by establishing a standard parameter interval, improves the efficiency, and reduces the production investment cost.

Description

Technical Field

[0001] This invention relates to the field of automotive trim parts processing and manufacturing technology, and in particular to a warping prevention production method based on Moldflow and a method for producing long strip injection molded parts. Background Technology

[0002] Cars are a very common means of transportation. With the development and progress of society and the gradual improvement of people's living standards, cars have gradually become more and more common in households. There are many types of cars, such as sedans, SUVs, MPVs, etc. Different types of cars have different appearances. Cars have a lot of accessories, among which large electroplated exterior parts in the shape of thin strips are often used.

[0003] With technological advancements, the requirements for the shape and size of electroplated exterior parts are becoming increasingly stringent. Because the substrate for electroplated parts is generally derived from electroplating-grade ABS plastic (a terpolymer of acrylonitrile, butadiene, and styrene), shrinkage and warping deformation can occur during injection molding due to the product's structure.

[0004] Warpage is a common defect in injection-molded plastic products, seriously affecting product quality. In the actual molding process, once the plastic part material and mold structure are determined, the molding process parameters become the main factors influencing warpage. Moldflow is a powerful computer-aided engineering (CAE) simulation software that uses its injection molding simulation tools to help verify and optimize plastic parts, injection molds, and injection molding processes. Summary of the Invention

[0005] The purpose of this invention is to provide a warp prevention production method based on Moldflow, so as to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0006] The technical solution adopted to solve the above-mentioned technical problems is as follows:

[0007] A warp prevention manufacturing method based on Moldflow includes the following steps:

[0008] Step 1: Through Moldflow simulation analysis, the theoretical deformation of the product warpage is automatically calculated;

[0009] Step 2: Further optimize the theoretical deformation amount using Moldflow to obtain the pre-deformation amount of warping;

[0010] Step 3: Reconfigure the pre-deformation amount and different holding pressure parameters in the Moldflow simulation analysis to obtain the corresponding warpage value. Based on the change in the warpage value, establish standard parameters for holding time and holding pressure.

[0011] Step 4: Fabricate the mold according to the pre-deformation amount;

[0012] Step 5: Perform a trial molding according to the standard parameters for holding time and holding pressure;

[0013] Step Six: Repair the mold according to the actual amount of warping deformation;

[0014] Step 7: Repeat steps 5 and 6 until the product dimensions meet the requirements after molding, then proceed with mass production.

[0015] The Moldflow-based anti-warping production method provided by this invention has at least the following beneficial effects: In the processing and production of long injection molded parts, the pre-deformation amount can be efficiently selected with the assistance of Moldflow simulation analysis, enabling the development of the injection mold. Furthermore, by rationally analyzing the influence of various holding pressure process parameters on warpage deformation through Moldflow, the influence law of process parameters on warpage deformation can be obtained. This provides necessary reference for the rational selection of process parameters and the reduction of warpage deformation in actual production, significantly reducing initial production costs and improving analysis efficiency. The Moldflow-based anti-warpage production method of this invention, based on Moldflow simulation analysis, sequentially determines the pre-deformation amount of the mold and the standard parameters of the holding pressure process, reducing the number of mold repairs and lowering repair costs. This reduces initial development costs and improves the quality and efficiency of production development.

[0016] As a further improvement to the above technical solution, step two specifically involves: automatically executing the optimization of injection molding simulation parameters through Moldflow, and obtaining the maximum warpage deformation value after completing the analysis.

[0017] As a further improvement to the above technical solution, the value obtained by multiplying the maximum warping deformation value after analysis by the empirical coefficient of deformation result 0.7 is used as the pre-deformation amount.

[0018] Due to differences in product structure and shape, there is a certain difference between the deformation amount simulated in Moldflow software and the actual deformation amount in injection molding production. Through the above technical solution, the pre-deformation amount can be corrected by empirical coefficients to avoid excessive pre-deformation.

[0019] As a further improvement to the above technical solution, step three specifically involves: the product's pressure holding molding process being a two-stage pressure holding process, including a first-stage pressure holding and a second-stage pressure holding under different pressure holding parameters.

[0020] As a further improvement to the above technical solution, during the pressure holding period, the holding time and pressure allow the stress inside the cavity to be released.

[0021] By using the above technical solution, a lower holding pressure is set in the first stage of holding pressure, which causes the injection screw to retract under the reaction force of the molten plastic injected into the cavity. The molten plastic near the gate will flow back, which releases the stress in the cavity. This allows the end of the product to cool down first, and then the middle section and gate position of the product to cool and form through the second stage of holding pressure, thereby achieving the purpose of controlling warpage deformation.

[0022] As a further improvement to the above technical solution, in the two-stage pressure holding process, the pressure holding time is changed to obtain the warpage value change curve, thereby determining the standard parameter of the pressure holding time.

[0023] As a further improvement to the above technical solution, after determining the standard parameters of the holding time, the warpage value change curve is obtained by changing the holding pressure, thereby determining the standard parameters of the holding pressure.

[0024] Establishing standard parameters for holding time and holding pressure based on the warp value variation curve requires setting multiple sets of holding times and pressures, which is a rather cumbersome process. The above technical solution can serve as a reference if standard parameters for products with similar shapes have already been established.

[0025] As a further improvement to the above technical solution, in steps four and five, the mold cavity template is reserved for mold repair thickness. After the cavity and core are processed, the mold assembly is carried out, but the water channel hole processing and the front mold polishing are not performed.

[0026] With the above technical solution, when reserving the thickness for mold repair in the cavity template, even if there are errors in the deformation data, these errors can be corrected by reprocessing by lowering the surface area. Eliminating the need for machining the water channels and polishing the front mold avoids damaging the water channels during mold repair, thus preventing mold scrapping.

[0027] As a further improvement to the above technical solution, in step seven, after completing the mold repair, the water channel holes of the mold are processed and the front mold is polished, and the mold is tested again. Once the product molding size meets the requirements, it can be put into mass production.

[0028] The present invention also provides a method for producing long injection molded parts, comprising the following steps:

[0029] First, based on the above-mentioned anti-warping production method based on Moldflow, the standard parameter range of holding time and holding pressure for long injection molded parts is obtained;

[0030] Next, when importing similar long injection molded parts into production, the standard parameters in the standard parameter range are configured in the Moldflow simulation analysis of the product, and the corresponding pre-deformation amount is obtained through optimization.

[0031] Then, molds are made according to the pre-deformation amount, and mass production is achieved through trial molding and mold repair.

[0032] The method for producing elongated injection molded parts provided by this invention has at least the following beneficial effects: After establishing a standard parameter range for similar elongated injection molded parts, during the production introduction process of new products, the standard parameters are configured into the simulation analysis of Moldflow to obtain the pre-deformation amount, and the mold is made according to the pre-deformation amount. In this method for producing elongated injection molded parts, after establishing the standard parameter range, the pre-deformation amount can be determined by Moldflow based on the standard parameter range, without the need to re-establish the standard parameters. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0034] Figure 1 This is a three-dimensional schematic diagram of a long strip injection molded product, an embodiment of the Moldflow-based anti-warping production method of the present invention.

[0035] Figure 2 This is a schematic diagram of the anti-warping production method based on Moldflow according to the present invention, and its embodiment is a product mold flow simulation analysis report obtained by Moldflow.

[0036] Figure 3 This is a schematic diagram of product warping after automatic optimization by Moldflow in an embodiment of the present invention.

[0037] Figure 4 This invention relates to a Moldflow-based anti-warping production method, and in its embodiments, a pressure attenuation curve is automatically optimized by Moldflow.

[0038] Figure 5 This is a curve showing the change in warpage value versus holding time in an embodiment of the Moldflow-based anti-warpage production method of the present invention.

[0039] Figure 6 This is a warpage curve of the anti-warpage production method based on Moldflow according to the present invention, and an embodiment thereof.

[0040] Figure 7 This is a schematic diagram of the product warping in an embodiment of the Moldflow-based anti-warping production method of the present invention;

[0041] Figure 8 This is a schematic diagram of the product placement in an embodiment of the Moldflow-based anti-warping production method of the present invention. Detailed Implementation

[0042] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0043] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not 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 limiting this invention.

[0044] In the description of this invention, if there are words such as "several", they mean one or more, "multiple" means two or more, "greater than", "less than", "exceeding" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself.

[0045] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0046] Reference Figures 1 to 8 The anti-warping production method based on Moldflow of the present invention is illustrated in the following embodiments:

[0047] A warp prevention manufacturing method based on Moldflow includes the following steps:

[0048] Step 1: The theoretical deformation of the product warpage is automatically calculated through Moldflow simulation analysis.

[0049] First, a 3D model of the long injection molded part is created. Then, the 3D model is imported into Moldflow simulation software for mold flow analysis to obtain the theoretical deformation.

[0050] Taking product A, a sheet-like exterior trim piece, as an example, product A has dimensions of 1223 x 44 mm and a wall thickness that gradually transitions from 2.5 to 3.4 mm. The 3D model of product A is attached. Figure 1 As shown in the attached figure, after importing the data into Moldflow for model flow analysis, the results are as follows. Figure 2 The Moldflow simulation analysis report shows that the theoretical deformation of product A obtained from the Moldflow simulation analysis is 41.98 mm.

[0051] In this embodiment, the product is 3D modeled in AutoCAD software and imported into Moldflow software. In other embodiments, other 3D modeling software such as PRO / E, Solidworks, UG, and Catia can be used, and the data can be imported into Moldflow software in STL, IGS, or STP formats. During the modeling process, small fillets, chamfers, and sharp corners should be avoided as much as possible, as their presence can easily cause a decrease in mesh distribution ratio and mesh quality, leading to failure of the model flow analysis.

[0052] Step 2: Optimize the theoretical deformation amount to obtain the pre-deformation amount of warping.

[0053] Specifically: Moldflow is used to automatically perform parameter optimization for injection molding simulation, including: importing the finite element mesh model, setting process parameters, and performing finite element analysis of warpage deformation. After the analysis is completed, the maximum warpage deformation value is obtained.

[0054] Because there is a certain difference between the deformation amount simulated in Moldflow software and the actual deformation amount produced in injection molding, directly using the simulated maximum warpage deformation value as the pre-deformation amount generally results in a large error, leading to a large amount of mold repair later. In this embodiment, the pre-deformation amount is obtained by multiplying the analyzed maximum warpage deformation value by the empirical coefficient of 0.7 for the deformation result.

[0055] Taking product A as an example again, after automatic analysis and optimization by Moldflow, the pressure attenuation in each area of ​​the product's warp location is uniform (e.g., Figure 4 As shown), the maximum warpage deformation value is 30.45mm upward, located at both ends of the product (e.g. Figure 3 (As shown). Therefore, the pre-deformation amount is set to 21mm.

[0056] Step 3: Reconfigure the pre-deformation amount and different holding pressure parameters in the Moldflow simulation analysis to obtain the corresponding warpage value. Based on the change of the warpage value, establish standard parameters for holding time and holding pressure.

[0057] Specifically: For a mold with a pre-deformation amount set to 21mm, the process parameters in Moldflow are set as follows: mold surface temperature 40℃, melt temperature 230℃, and injection speed 65mm / s. These process parameters are set according to the product material and shape. Under these process parameters, standard parameters for holding time and holding pressure are established based on the warpage values ​​obtained from different holding pressure parameters.

[0058] In this embodiment, the product's pressure-holding molding process is a two-stage pressure-holding process, including a first-stage pressure-holding and a second-stage pressure-holding with different pressure-holding parameters. A lower pressure is set in the first stage, causing the injection screw to retract under the reaction force of the molten plastic injected into the cavity. This causes the molten plastic near the gate to flow back, releasing the stress within the cavity. This allows the end of the product to cool down first, and then the middle section and gate area are cooled and molded through the second-stage pressure-holding, thereby controlling warpage.

[0059] When using a single-stage pressure holding process, the molding effect on the product is not significant because the stress within the mold cavity is not released. Referring to Table 1, with a pressure of 80 MPa as the baseline, increasing or decreasing the pressure by 50% results in minimal change in the warpage value. However, when using a two-stage pressure holding process, the holding time and pressure of the first stage are set to 1 second and 5 MPa respectively, depending on the injection pressure. This allows the injection screw to retract, releasing the stress within the mold cavity, and resulting in a significant change in the warpage value.

[0060]

[0061] Table 1

[0062] The holding pressure for the two-stage holding pressure is first set according to the pressure parameter of 80 MPa used in the automatic calculation in step one, and the standard parameter of holding pressure time is determined by obtaining the warp value change curve by changing the holding pressure time.

[0063] Specifically, referring to Table 2 below, the pressure parameters for the first stage of pressure holding are set to a holding time of 1 second and a holding pressure of 5 MPa; the holding pressure for the second stage of pressure holding is set to 80 MPa. By setting the holding time to 5, 8, 10, and 12 seconds respectively, the corresponding warpage values ​​are +3.2, -0.9, -3.5, and -4.2 mm. Based on this, a curve showing the change between the holding time and the product warpage value when the second stage of pressure holding is set to 80 MPa is attached. Figure 5 As shown.

[0064]

[0065] Table 2

[0066] Based on the change curve and taking into account potential issues such as surface shrinkage during product molding, the standard parameter for holding time is selected as 8s, with a deformation amount of -1mm as the benchmark.

[0067] After determining the standard parameters for the holding time, the warpage value variation curve is obtained by changing the holding pressure, thereby determining the standard parameters for the holding pressure. Specifically, refer to the table below (Table 3): the pressure parameters for the first stage of holding pressure are still set to a holding time of 1 second and a holding pressure of 5 MPa; the holding time for the second stage of holding pressure is set to 8 seconds. By setting the holding pressure to 40, 60, 80, 100, and 120 MPa respectively, the corresponding warpage values ​​are -1.5, -1.7, -0.9, +1.4, and +2.6 mm. Based on this, the variation curve of the holding pressure and the product warpage value when the second stage holding time is set to 8 seconds can be plotted as shown in the attached figure. Figure 6 As shown.

[0068]

[0069] Table 3

[0070] Based on the change curve and taking into account potential issues such as surface shrinkage during product molding, the standard parameter for holding pressure is selected as 80 MPa, with a deformation of -1 mm as the benchmark.

[0071] It is worth noting that in Tables 1, 2, and 3 above, when the warpage value is positive, the warped portion is in an upward-curving state relative to the original cavity (e.g., Figure 7 As shown); when the warpage value is negative, the warped portion is in a collapsed state relative to the original cavity (as shown). Figure 8 (As shown).

[0072] Step 4: Make a mold according to the pre-deformation amount.

[0073] To avoid the need for mold repair and re-molding, the mold cavity template has an additional 20mm thickness allowance beyond the required thickness and strength. Even if there are errors in the deformation data, these can be corrected by re-machining with a lower surface area. Furthermore, considering that lowering the surface area after the water channel holes have already been machined could easily break the water channel and render the mold unusable, in step four, after completing the machining of the cavity and core, the mold can be assembled and tested.

[0074] Step 5: Perform a trial molding according to the standard parameters for holding time and holding pressure.

[0075] Specifically, the holding time of the first stage of pressure holding is 1 second, and the holding pressure is 5 MPa; the holding time of the second stage of pressure holding is 8 seconds, and the holding pressure is 80 MPa.

[0076] Step 6: Repair the mold according to the actual warpage deformation of the product under pre-deformation.

[0077] Step 7: Repeat steps 5 and 6 until the product dimensions meet the tolerance requirements of the product drawings, then proceed to mass production. Since step 4 involves machining the water channels and polishing the front mold, after completing the mold repair, machine the water channels and polish the front mold again, and perform another trial molding to ensure that the product dimensions meet the requirements before proceeding to mass production.

[0078] Establishing standard parameters for holding time and holding pressure using the warp value variation curve requires setting multiple sets of holding time and holding pressure, which is a rather cumbersome process. This invention also provides a method for producing long strip injection molded parts.

[0079] First, based on the Moldflow-based anti-warping production method described above, the standard parameter range for holding time and holding pressure of the long injection molded parts is obtained. During the initial production of each product, the determined standard parameters for each product should be recorded. Multiple similar long injection molded parts can form a standard parameter range.

[0080] Then, when importing similar long injection molded parts into production, the standard parameters in the standard parameter range are configured in the Moldflow simulation analysis of the product, and the corresponding pre-deformation amount is obtained through optimization.

[0081] Finally, the mold is directly manufactured based on the pre-deformation amount, without the need to reserve thickness for mold repair, and the processing of water channels and polishing of the front mold can be completed directly. Then, through trial molding and mold repair, the mold is improved and verified, and the product quality is improved in stages until it meets the drawing requirements, ultimately achieving mass production.

[0082] After establishing standard parameter ranges for similar long injection molded parts, these standard parameters are configured into Moldflow's simulation analysis during the production introduction of new products to obtain pre-deformation amounts. Molds are then fabricated based on these pre-deformation amounts. Once the standard parameter ranges are established, the pre-deformation amounts can be determined by Moldflow based on these ranges, eliminating the need to re-establish the standard parameters.

[0083] Specifically, for long plastic parts such as signs and nameplates, the injection speed of molten plastic is generally between 30 and 55 mm / s, and the standard range of its holding pressure parameters can be referred to in the table below (Table 4).

[0084]

[0085] Table 4

[0086] For decorative strip-type long injection molded parts, their structure is more complex than that of lettering and signage-type long plastic parts. The injection speed of molten plastic is generally between 65 and 95 mm / s. The standard range of its holding pressure parameters can be referred to in the table below (Table 5).

[0087]

[0088] Table 5

[0089] Based on the aforementioned standard pressure holding parameter ranges (Tables 4 and 5), long injection molded parts such as lettering, signs, and decorative strips can have their standard parameters directly set during Moldflow simulation analysis when imported into production. After obtaining the pre-deformation amount, the mold can be fabricated based on this pre-deformation amount. This eliminates the need to re-establish standard parameters through Moldflow, significantly improving efficiency. Mold fabrication based on the pre-deformation amount eliminates the need for pre-machining allowances in the cavity template and postpones the machining of water channels and the polishing of the front mold, reducing the number of trial moldings and repairs, and further improving efficiency.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] Although embodiments of the present invention have been shown and described, those skilled in the art can make various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the invention. All such changes, modifications, equivalent alterations or substitutions are included within the scope defined by the claims of this application, and the scope of the invention is defined by the claims and their equivalents.

Claims

1. A moldflow based anti-warping production method, characterized by: The method comprises the following steps: Step 1: automatically measuring and calculating the theoretical deformation of product warping through simulation analysis of Moldflow; Step 2: continuously optimizing the theoretical deformation through Moldflow to obtain a pre-deformation of warping; Step 3: reconfiguring the pre-deformation and different holding pressure parameters in the simulation analysis of Moldflow to obtain corresponding warping values, and establishing standard parameters of holding pressure time and holding pressure according to the change of the warping values; Specifically, the holding pressure forming process of the product is two-stage holding pressure, including one-stage holding pressure and two-stage holding pressure under different holding pressure parameters; in the one-stage holding pressure, the holding pressure time and the holding pressure are set according to the injection pressure, so that the stress in the cavity can be released; in the two-stage holding pressure, the holding pressure is set according to the pressure parameter automatically calculated in step 1, and then the warping value change curve is obtained by changing the holding pressure time, so as to determine the standard parameter of the holding pressure time; after the standard parameter of the holding pressure time is determined, the warping value change curve is obtained by changing the holding pressure, so as to determine the standard parameter of the holding pressure; Step 4: manufacturing a mold according to the pre-deformation; Step 5: trial molding according to the standard parameters of the holding pressure time and the holding pressure; Step 6: repairing the mold according to the actual warping deformation; Step 7: repeating steps 5 and 6 until the size of the product after forming meets the requirements, and then introducing mass production.

2. The Moldflow-based warpage-preventing production method according to claim 1, characterized by: Specifically, step 2: automatically executing the optimization of injection molding simulation parameters through Moldflow, and obtaining the maximum warping deformation value after analysis.

3. The Moldflow-based warpage-preventive production method according to claim 2, characterized by: The pre-deformation is the value obtained by multiplying the maximum warping deformation value after analysis by an empirical coefficient 0.

7.

4. The Moldflow-based warpage-prevention production method according to claim 1, characterized by: In steps 4 and 5, the mold cavity template of the mold is reserved with a repair thickness, and after the processing of the cavity and the core is completed, the mold is assembled, and the water hole processing and the front mold polishing are not performed.

5. The Moldflow-based warpage-preventive production method according to claim 4, characterized by: In step 7, after the mold is repaired, the water hole processing and the front mold polishing are performed on the mold, and trial molding is performed again, and the product forming size meets the requirements, and then mass production is introduced.

6. A method of producing a long strip injection molded part, characterized by: The method comprises the following steps: First, obtaining the standard parameter interval of the holding pressure time and the holding pressure of a long strip injection molded part according to the Moldflow-based anti-warping production method of any one of claims 1 to 3; Next, when introducing production of similar long strip injection molded parts, configuring the standard parameters in the standard parameter interval in the simulation analysis of Moldflow on the product, and optimizing to obtain a corresponding pre-deformation; Then, manufacturing a mold according to the pre-deformation, and realizing mass production through trial molding and mold repair.

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