Injection-molded parts for vehicle sub-instrument assemblies and their manufacturing methods, vehicles

Abstract

This application provides an injection-molded part for a vehicle auxiliary instrument assembly, a method for its preparation, and a vehicle. The injection-molded part provided by this application is made of a polypropylene composite material, which comprises at least the following components by weight: 30-35 parts of highly crystalline copolymer polypropylene; 25-30 parts of homopolymer polypropylene; 25-30 parts of glass fiber; 3-5 parts of toughening agent; 2-3 parts of nucleating agent; and 0.2-0.4 parts of whiskers; wherein the glass fiber has a specification of 2400 tex. The polypropylene composite material prepared using the above proportions enables the lightweighting of the auxiliary instrument assembly.

Description

Technical Field

[0001] This application relates to the field of vehicles, and more specifically, to an injection-molded part for a vehicle sub-instrument assembly, a method for its preparation, and a vehicle. Background Technology

[0002] With the trend towards lightweighting in the automotive industry, injection-molded parts made of polypropylene composites have been widely used in automotive components. Thermoplastic polypropylene, due to its good processability and recyclability, is ubiquitous in everyday life. However, because the strength and hardness of thermoplastics still lag behind those of metals, thermoplastic products are generally used as non-structural components and are difficult to use as structural load-bearing parts.

[0003] By combining thermoplastic polypropylene with glass fiber, its hardness and strength are significantly enhanced. Compared to unmodified thermoplastic polypropylene, the reinforced composite material exhibits approximately twice the tensile strength, more than 1.4 times the flexural strength, and approximately 2.2 times the flexural modulus. Simultaneously, dimensional stability is optimized, heat distortion is reduced, shrinkage is decreased, material hardness is increased, and water absorption is reduced. Furthermore, thermal stability is improved, with a significantly higher heat resistance temperature compared to unmodified polypropylene, making it suitable for products requiring high temperature resistance and strength.

[0004] With the increasing demand for lightweight materials, how to reduce the density of materials while ensuring both product performance and cost requirements, and achieve good comprehensive performance to meet product needs, has become a key research direction for major scientific research institutions. Summary of the Invention

[0005] This application provides an injection-molded part for a vehicle sub-instrument assembly, a method for manufacturing the same, and a vehicle, which enables the sub-instrument to be lightweight.

[0006] Specifically, this application is implemented through the following technical solution:

[0007] One aspect of this application provides an injection-molded part for a vehicle sub-instrument assembly, said injection-molded part being made of a polypropylene composite material, said polypropylene composite material comprising at least the following components by weight:

[0008] 30-35 parts of highly crystalline copolymer polypropylene;

[0009] 25-30 parts of homopolymer polypropylene;

[0010] 25-30 parts glass fiber;

[0011] 3-5 parts toughening agent, 2-3 parts nucleating agent, 0.2-0.4 parts whiskers;

[0012] The glass fiber has a specification of 2400 tex.

[0013] Optionally, the polypropylene composite material further includes the following components in parts by weight:

[0014] Antioxidant 0.1-0.3 parts, lubricant 0.1-0.3 parts, scratch resistant agent 0.1-0.3 parts, light stabilizer 0.05-0.15 parts.

[0015] Optionally, the toughening agent is selected from one or more of ethylene propylene diene monomer (EPDM), ethylene propylene rubber (EPR), thermoplastic elastomer (SEBS), and polyolefin elastomer (POE).

[0016] Optionally, the side of the injection molded part includes a first sidewall and a second sidewall disposed opposite to each other. The first sidewall is used to fix the parts inside the injection molded part. The surface of the first sidewall is provided with an outwardly protruding first reinforcing rib, and the first reinforcing rib is distributed in a polygonal shape. Along the height direction of the injection molded part, the first sidewall includes a first region, a second region and a third region arranged sequentially up and down. The number of parts fixed in the second region is greater than the number of parts fixed in the first region and greater than the number of parts fixed in the third region.

[0017] The first reinforcing ribs in the first region are distributed in multiple first polygons, the first reinforcing ribs in the second region are distributed in multiple second polygons, and the first reinforcing ribs in the third region are distributed in multiple third polygons. The number of sides of the second polygons is greater than the number of sides of the first polygons and greater than the number of sides of the third polygons.

[0018] Optionally, the surface of the second sidewall is provided with an outwardly protruding second reinforcing rib, which is distributed in multiple regular hexagons on the second sidewall.

[0019] Optionally, the side of the injection molded part further includes a third sidewall, which connects the first sidewall and the second sidewall. The third sidewall has a drawer opening and a third reinforcing rib extending toward the interior of the injection molded part. The cross-section of the third reinforcing rib is double H-shaped.

[0020] Optionally, the injection molded part further includes a top wall, the three sides of which are respectively connected to the first side wall, the second side wall and the third side wall, and the length of the top wall is less than the length of the first side wall along the thickness direction of the injection molded part;

[0021] Along the thickness direction of the injection molded part, the first region includes a first sub-region and a second sub-region distributed side by side, and the side length of the top wall includes the side length of the first sub-region and part of the side length of the second sub-region. The reinforcing ribs of the first sub-region are distributed in multiple squares, and the reinforcing ribs of the second sub-region are distributed in multiple rectangles.

[0022] Optionally, the top wall is provided with at least one first protrusion facing the interior of the injection molded part, and at least one second protrusion facing the exterior of the injection molded part; and / or

[0023] The top wall has multiple weight-reduction holes.

[0024] Another aspect of this application provides a method for manufacturing an injection-molded part for a vehicle sub-instrument assembly, comprising:

[0025] The raw materials are mixed to form a polypropylene composite material, wherein the raw materials include: 30-35 parts of highly crystalline copolymer polypropylene, 25-30 parts of homopolymer polypropylene, 25-30 parts of glass fiber, 3-5 parts of toughening agent, 2-3 parts of nucleating agent, 0.2-0.4 parts of whiskers, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of lubricant, 0.1-0.3 parts of scratch resistant agent, and 0.05-0.15 parts of light stabilizer, wherein the glass fiber has a specification of 2400 tex;

[0026] The molten polypropylene composite material is integrally injection molded into the injection molded part using an injection mold.

[0027] Optionally, in the step of integrally injection molding the molten polypropylene composite material into the injection molded part through an injection mold, the temperature of the injection mold is 50-60℃, the melt temperature is 230-240℃, the injection speed is 40-60mm / s, the back pressure is 165-170bar, and the holding pressure is 30-42MPa.

[0028] Another aspect of this application provides a vehicle including any of the injection-molded parts described above.

[0029] This application provides an injection-molded part for a vehicle sub-instrument assembly and its manufacturing method. The part uses fine-gauge glass fibers and is a composite material prepared according to the formulation specified in this application. Essentially, polyethylene (PVE) is added to a glass fiber composite polypropylene material to plasticize the composite, thereby altering the raw material ratio. Furthermore, the fine-gauge glass fibers result in a polypropylene composite material with a low density, as measured experimentally, achieving material lightweighting. Products made using the modified polypropylene composite material of this application are more than 7% lighter than those made with traditional materials, achieving product lightweighting. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a secondary instrument assembly shown in an exemplary embodiment;

[0031] Figure 2 This is a schematic diagram of an injection-molded part shown in an exemplary embodiment of this application;

[0032] Figure 3 This is a left view of an injection-molded part shown in an exemplary embodiment of this application;

[0033] Figure 4 This is a right view of an injection-molded part shown in an exemplary embodiment of this application;

[0034] Figure 5 This is a front view of an injection-molded part shown in an exemplary embodiment of this application;

[0035] Figure 6 This is a top view of an injection-molded part shown in an exemplary embodiment of this application;

[0036] Figure 7 This is a flowchart illustrating an exemplary embodiment of the present application of a method for preparing an injection molded part. Detailed Implementation

[0037] The technical solutions in the embodiments (or "implementations") of this application will be clearly and completely described herein with reference to the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0038] If the embodiments of this application contain terms relating to directional indications or positional relationships (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationships and movements between components in a specific posture (as shown in the attached figures); if the specific posture changes, the directional indications or positional relationships will also change accordingly. Furthermore, the terms "first" and "second" used in the embodiments of this application are only for descriptive convenience and should not be construed as indicating or implying relative importance.

[0039] Currently, automotive interior and exterior frame components are primarily made of composite materials containing 30% glass fiber and polypropylene resin, with a density exceeding 1.15 g / cm³, indicating a relatively high density. With the trend towards lightweighting in automobiles, combined with... Figure 1 and Figure 2 This application provides an injection-molded part 100 for a vehicle sub-instrument assembly. The vehicle sub-instrument consists of the injection-molded part 100 and a skin 200. The injection-molded part 100 is the skeleton of the sub-instrument, and the skin 200 surrounds the outside of the injection-molded part 100.

[0040] The injection molded part 100 is made of polypropylene composite material, mainly a composite of glass fiber and polypropylene. The polypropylene composite material includes at least the following components by weight: 30-35 parts of highly crystalline copolymer polypropylene (e.g., 30, 32, 35 parts); 25-30 parts of homopolymer polypropylene (e.g., 25, 28, 30 parts); 25-30 parts of glass fiber (e.g., 25, 26, 30 parts); and 3-5 parts of toughening agent (e.g., 3, 4, 5 parts); 2-3 parts of nucleating agent (e.g., 2, 2.5, 3 parts); and 0.2-0.4 parts of whiskers (e.g., 0.2, 0.3, 0.4 parts). The glass fiber has a specification of 2400 tex.

[0041] The whiskers can be magnesium oxysulfate whiskers, which can form a good interfacial bond with the polypropylene matrix, more effectively transferring stress and preventing crack propagation, thereby improving the overall strength of the material. An exemplary whisker can be type 152 magnesium oxysulfate whiskers. Nucleating agents can accelerate the crystallization rate; an exemplary nucleating agent can be maleic anhydride.

[0042] This application involves adding polyethylene (PVE) to a glass fiber composite polypropylene material to plasticize the composite and thus alter the raw material ratio. Furthermore, the glass fibers are finer, resulting in a polypropylene composite material with a lower density, as measured experimentally, achieving material lightweighting. Products made from the modified polypropylene composite material of this application are more than 7% lighter than those made from traditional materials, achieving product weight reduction.

[0043] In one embodiment, the polypropylene composite material further includes the following components by weight: 0.1-0.3 parts antioxidant, 0.1-0.3 parts lubricant, 0.1-0.3 parts scratch resistant agent, and 0.05-0.15 parts light stabilizer. Specifically, the components may be 0.2 parts antioxidant, 0.2 parts lubricant, 0.2 parts scratch resistant agent, and 0.1 parts light stabilizer. The light stabilizer can improve the light stability of the composite material; an exemplary light stabilizer may be light stabilizer 770. The antioxidant is 1010 antioxidant. The lubricant facilitates the mixing of the raw materials. The scratch resistant agent can improve the scratch resistance of the material. For example, the lubricant may include at least one of polyethylene wax, polypropylene wax, etc. The scratch resistant agent may include at least one of tetraboride, nano-zirconia, erucamide, and oleamide, etc.

[0044] In another embodiment, the toughening agent is selected from one or more of ethylene propylene diene monomer (EPDM), ethylene propylene rubber (EPR), thermoplastic elastomer (SEBS), and polyolefin elastomer (POE). The toughening agent can improve the toughness of the composite material, enhance its crack resistance, and increase the mechanical strength of the resulting polypropylene composite material.

[0045] In one embodiment, combined with Figure 2 and Figure 3 The side portion of the injection molded part 100 includes a first sidewall 110 and a second sidewall 120 disposed opposite to each other. The first sidewall 110 is used to fix parts inside the injection molded part 100. The surface of the first sidewall 110 is provided with outwardly protruding first reinforcing ribs, and the first reinforcing ribs are distributed in a polygonal pattern. Along the height direction z of the injection molded part 100, the first sidewall 110 includes a first region 111, a second region 112, and a third region 113 arranged sequentially vertically. The number of parts fixed in the second region 112 is greater than the number of parts fixed in the first region 111, and is greater than the number of parts fixed in the third region 113.

[0046] The first reinforcing ribs in the first region 111 are distributed in multiple first polygons 20, the first reinforcing ribs in the second region 112 are distributed in multiple second polygons 30, and the first reinforcing ribs in the third region are distributed in multiple third polygons 40. The number of sides of the second polygons 30 is greater than the number of sides of the first polygons 20 and also greater than the number of sides of the third polygons 40. Furthermore, the uniformity of the distribution of the sides of the second polygons 30 is greater than that of the first polygons 20 and the third polygons 40. Structural strength is related to the symmetry and uniformity of the structure; structural shapes with better symmetry and uniformity can generally more effectively disperse and resist external forces. Therefore, the structural strength of the second polygons 30 in this application is greater than that of the first polygons 20 and the third polygons 40.

[0047] The second region 112 has more fixing points for components such as brackets and wiring harnesses inside the secondary instrument panel, thus bearing a greater load and requiring greater strength. Therefore, in this embodiment, the first reinforcing ribs of the second region 112 are arranged as multiple second polygons 30. Dividing the secondary instrument panel into three regions with different shapes of first reinforcing ribs is to meet the strength requirements of different regions. Depending on the installation of components at different locations, when the secondary instrument panel is assembled inside the vehicle, the corresponding interior environment of different regions, the shape of different side walls, and the fixing positions of the brackets and wiring harnesses inside the injection molded part 100 all need to be considered, and the shape distribution of the first reinforcing ribs is designed in conjunction with the strength requirements of each location.

[0048] In one embodiment, the first polygon 20 is a quadrilateral, including squares and rectangles. The second polygon 30 is a regular hexagon, i.e., a honeycomb pattern. The third polygon 40 is a rectangle.

[0049] It should be noted that the regular hexagon of the second polygon 30 will conform to the outline of the second region 112, presenting a partial structure or deformation of a regular hexagon. The structural strength of a regular hexagon is greater than that of a quadrilateral or a rectangle.

[0050] The wall thickness of the injection molded part 100 can be designed to be 2.5-3.0mm, such as 2.5mm, 2.8mm, 3.0mm, etc. The first reinforcing rib protrudes 2mm from the surface of the first sidewall 110. The first region 111, facing the interior of the injection molded part (not shown in the figure), can be designed with a 1*3mm rectangular weight-reducing hole and a 1*2mm oblong weight-reducing hole. The weight-reducing hole is designed to meet the requirements of lightweighting while ensuring the strength of the first region 111. At the same time, the first region 111 also includes two first mounting bosses 51. The surface of the mounting bosses is provided with groove-shaped fixing holes for fixed connection with the skin 200 of the auxiliary instrument through threaded connectors. The threaded connectors can be M6 bolts. The mounting bosses protrude outward from the surface of the first sidewall 110, and the height is greater than the height of the first reinforcing rib. The second region 112 is provided with one second mounting boss 52, and the third region 113 is provided with one third mounting boss 53. The number of mounting bosses in different areas is related to the shape of the skin 200 corresponding to the first sidewall 110. Areas with larger surface areas and heavier weight of the skin 200 have more mounting bosses to ensure the stability of the skin 200's fixing surface to the first sidewall 110. Specifically, the height of the first mounting boss 51 in the first area 111 is 10mm-15mm, and the width is 5mm-10mm. The height of the second mounting boss 52 in the second area 112 is 9mm-12mm, and the width is 3mm-8mm. The height of the third mounting boss 53 in the third area 113 is 10mm-12mm, and the width is 5mm-8mm. These different heights are related to the distance between different areas of the skin 200 and the sidewall areas of the injection molded part.

[0051] Due to spatial design limitations, the second region 112 can have a portion of its structure cut off from a regular hexagon to match the outline of the second region 112 and the outline of parts such as mounting and fixing bosses. The first rectangular reinforcing ribs of the third region 113 are mostly composed of 3mm*4mm rectangles 41. However, given the spatial limitations of the third region 113 structure, a 1*1 triangle structure 42 can be designed with the two corners removed from the rectangle. Alternatively, other first reinforcing rib shapes can be modified from the 3mm*4mm rectangle 41. This allows for a more abundant and rational distribution of the 3mm*4mm rectangle 41-shaped first reinforcing ribs in the third region.

[0052] In one embodiment, combined with Figure 4The surface of the second sidewall 120 is provided with an outwardly protruding second reinforcing rib, the protrusion height of which can be 2mm. The second reinforcing rib of the second sidewall 120 is distributed in multiple regular hexagons. The number of parts, wiring harnesses or brackets inside the auxiliary instrument is small near the second sidewall 120, and the number of installation points that need to be designed is also small. Therefore, the second sidewall 120 does not need a complex second reinforcing rib structure design to meet the strength requirements.

[0053] The second sidewall 120 is provided with four fourth mounting and fixing bosses 54, with a height of 9mm-12mm and a width of 3mm-8mm. Due to space design limitations, the distribution of the second reinforcing ribs of the second sidewall 120 can be based on a regular hexagon, by cutting off a portion of the structure to match the outline of the second sidewall 120 and the outline of the mounting and fixing bosses and other parts.

[0054] In one embodiment, reference Figure 2 and Figure 5 The injection-molded part 100 also includes a third sidewall 130, which connects to the first sidewall 110 and the second sidewall 120. The third sidewall 130 has a drawer opening 131 and a third reinforcing rib 132. The third reinforcing rib 132 extends inwards towards the interior of the injection-molded part, and its cross-section is double-H shaped, specifically with two H-shaped sections laterally distributed and connected to each other. The H-shaped structure can more effectively disperse stress. When external force is applied to the structure, the double-H shaped reinforcing rib can evenly transfer the stress to the entire structure, thereby avoiding damage caused by excessive local stress. Because the third sidewall 130 has a drawer opening 131, its structure is relatively weak. The third reinforcing rib 132 can strengthen both the overall strength of the third sidewall 130 and the strength of the drawer opening 131.

[0055] The third reinforcing rib 132 has a width of 40mm-60mm, a length of 150mm-200mm, and extends 150mm-200mm into the injection molded part.

[0056] In one embodiment, combined with Figure 6 The injection-molded part 100 also includes a top wall 140, which is the platform of the sub-instrument assembly. The three sides of the top wall 140 connect to the first side wall 110, the second side wall 120, and the third side wall 130, respectively. Along the thickness direction y of the injection-molded part, the length of the top wall 140 is less than the length of the first side wall 110. From the top view, the top wall, the first side wall 110, and the second side wall 120 present... The countertop has a U-shaped structure. Users typically place items such as water glasses, keys, and mobile phones on the countertop, which also requires strong structural strength.

[0057] Along the thickness direction y of the injection molded part 100, the first region 111 includes a first sub-region 1111 and a second sub-region 1112 arranged side-by-side, and the side length of the top wall 140 includes the side length of the first sub-region 1111 and a portion of the side length of the second sub-region 1112. The first reinforcing ribs of the first sub-region 1111 are distributed in multiple squares, and the first reinforcing ribs of the second sub-region 1112 are distributed in multiple rectangles. The structural strength of a square is greater than that of a rectangle, while a rectangle can achieve weight reduction compared to a square.

[0058] The surface of the injection-molded part 100 is located above the first sub-region 1111, where users typically place items such as mobile phones and keys. The entire first sub-region 1111, and part of the second sub-region 1112, serve as the sidewall supporting the top wall 140. Therefore, the first sub-region 1111 requires greater structural strength than the second sub-region 1112. Thus, the first reinforcing rib of the first sub-region 1111 is designed as a square. The second sub-region 1112, not requiring greater strength, can be designed with a rectangular first reinforcing rib to meet some lightweighting requirements. The square is a 5mm × 5mm square 21, and the rectangle can include 5mm × 8mm or 5mm × 3mm rectangles 22. For some local structures with relatively low stress, a pentagonal grid structure formed by removing 1×1 triangles from the corners of an 8×3 rectangular grid can be designed.

[0059] In one embodiment, the top wall 140 is provided with at least one first protrusion 141 facing inward toward the injection molded part 100, and at least one second protrusion 142 facing outward toward the injection molded part 100. The presence of the first protrusion 141 and the second protrusion 142 increases the area of ​​the tabletop, i.e., the force-bearing area of ​​the tabletop. Compared to a tabletop with an entirely planar structure, the tabletop in this embodiment can withstand greater impact strength along the thickness direction y of the auxiliary instrument. The second protrusions 142 are distributed on both sides of the first protrusion 141, giving the top wall a "U" shape. On the surface of the second protrusion 142, to ensure the installation of the skin 200, fifth mounting bosses 55 can be provided. On both sides of the first protrusion 141, one side of the second protrusion 142 is designed with six fifth mounting bosses 55, and the other side is designed with three fifth mounting bosses 55. Alternatively, multiple first protrusions 141 and multiple second protrusions 142 can be provided.

[0060] Multiple weight-reducing holes are provided on the top wall at 140mm to achieve lightweighting while meeting the required strength of the countertop. The weight-reducing holes are 6mm*8mm in size, and there are 18 of them arranged in a 6*3 pattern.

[0061] The structural design of the aforementioned injection molded part 100 is based on the mechanical properties of polypropylene composite materials, as well as the stress analysis, stiffness and strength analysis, and lightweight considerations of various positions in the auxiliary instrument assembly.

[0062] refer to Figure 7 This application also provides a method for manufacturing an injection-molded part for a vehicle sub-instrument assembly, comprising:

[0063] S100. The raw materials are mixed to form a polypropylene composite material, wherein the raw materials include: 30-35 parts of highly crystalline copolymer polypropylene, 25-30 parts of homopolymer polypropylene, 25-30 parts of glass fiber, 3-5 parts of toughening agent, 2-3 parts of nucleating agent, 0.2-0.4 parts of whiskers, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of lubricant, 0.1-0.3 parts of scratch resistant agent, and 0.05-0.15 parts of light stabilizer, wherein the glass fiber has a specification of 2400 tex.

[0064] S200. The molten polypropylene composite material is integrally injection molded into the injection molded part using an injection mold.

[0065] Specific step S100 may include: first, weighing the raw materials according to the composition formula; mixing the high-crystallinity copolymer polypropylene, homopolymer polypropylene, toughening agent, nucleating agent, and other related additives evenly in a high-speed mixer; then adding the mixture to an extruder for plasticizing and compounding; the fully compounded melt enters a specially designed die head, where the raw material glass fiber passes through the specially designed die head, completing dispersion, wetting, and melt encapsulation, thus compounding the glass fiber with the polypropylene. Subsequently, under traction, the mixture is cooled and shaped through a die, cut to form a blend, and then extruded and granulated.

[0066] The extruder temperature is set between 120 and 280°C, depending on the product performance requirements. The screw speed is set at 450 rpm, the injection temperature at 190–210°C, the injection pressure at 30 MPa, and the screw speed at 359 rpm. The extruded granules are then dried at 85°C for 2 hours.

[0067] The above experimental process can produce a glass fiber reinforced polypropylene composite material with strength and stiffness that meets the performance requirements of the sub-instrument assembly, and achieve low cost and lightweight.

[0068] By designing reinforcing ribs of different shapes and quantities and weight-reducing holes at different locations, and through joint analysis of materials and structure, the shape of the injection molded part is determined, and then injection molding is performed.

[0069] Therefore, the injection-molded part of the vehicle sub-instrument assembly manufactured in this application can meet the design requirements for modality, lightness, and stiffness, and achieve lightweighting.

[0070] In one embodiment, during the step of integrally injection molding the molten polypropylene composite material into the injection molded part using an injection mold, the temperature of the injection mold is 50-60°C, the melt temperature is 230-240°C, the injection speed is 40-60 mm / s, the back pressure is 165-170 bar, and the holding pressure is 30-42 MPa. Injection speed refers to the movement speed of the screw or plunger during injection.

[0071] The specific injection molding process involves adding the raw material into the barrel of the injection molding machine and performing injection molding according to the aforementioned process parameters. The back pressure of this application is 165-170 bar, and the holding pressure is 30-42 MPa, enabling rapid mold filling of the mixture. Using the process parameters of this application significantly affects the filling of the plastic melt, noticeably reducing defects such as weld lines and warpage. Furthermore, the injection-molded products exhibit high surface quality, are free of flow marks, and have high tensile strength and tensile modulus. While injection speed has a less significant impact on product quality than melt temperature and mold temperature, it directly affects the injection cycle time. To improve injection efficiency and reduce the injection cycle time, the injection speed needs to be optimized appropriately.

[0072] Increasing the mold temperature can effectively reduce internal stress and orientation of the product, while also improving the mold's undercooling, which is beneficial for improving the product's appearance quality. However, the mold temperature should not be too high, as this will reduce the impact strength in the streamline direction and increase the shrinkage rate.

[0073] Increasing the melt temperature is beneficial to the fluidity of the melt and can reduce the shrinkage of the product. However, excessively high temperatures are not advisable. When the melt temperature approaches the upper limit of the injection molding temperature, it is easy to generate a lot of gas, causing defects such as bubbles, voids, and discoloration in the plastic.

[0074] Injection speed, back pressure, and holding pressure all have some effect on reducing shrinkage and warpage, but the improvement is not significant. The main reason is that as the injection and cooling times reach a certain point, the melt is fully solidified, achieves sufficient rigidity, and tends to a constant value, while the shrinkage rate gradually stabilizes.

[0075] Table 1 below shows the manufacturing method of the injection-molded part for the vehicle sub-instrument assembly according to this application, and the performance of the injection-molded parts obtained by using different process parameters.

[0076]

[0077] Table 1

[0078] The first column shows the process parameters used in the preparation of auxiliary instruments using traditional polypropylene composite materials. Columns two through six show different process parameters used in the preparation of injection molded parts with the polypropylene composite material described in this application. As shown in Table 1, the appearance of the products in columns two through six is ​​significantly improved compared to the first column, indicating that injection molded parts with better appearance quality can be produced using the composite material provided in this application. Columns five and six show products with fewer or no shrinkage marks, demonstrating that appropriate process parameters can meet the appearance requirements of the products.

[0079] The following are embodiments of this application:

[0080] Example 1

[0081] First, weigh the raw materials according to the following mass ratio: 32 parts of high crystallinity copolymer polypropylene, 28 parts of homopolymer polypropylene, 26 parts of glass fiber, 4 parts of toughening agent ethylene propylene diene monomer (EPDM), 2.5 parts of nucleating agent maleic anhydride, 0.3 parts of type 152 magnesium oxysulfate whiskers, 0.2 parts of 1010 antioxidant, 0.2 parts of lubricant polyethylene wax, 0.2 parts of scratch resistant agent tetraboride, and 0.1 parts of light stabilizer 770 component.

[0082] Next, the raw materials are mixed evenly in a high-speed mixer. Then, the mixture is added to an extruder for plasticizing and kneading. The fully kneaded melt enters a specially designed die head, where continuous glass fibers also pass through. Within this die head, the fibers are dispersed, impregnated, and encapsulated in the melt. Subsequently, under traction, the mixture is cooled, shaped, and cut through a die to form a blend, which is then extruded and granulated. The extruder is configured with an extrusion temperature of 200℃, a speed of 450 r / min, an injection temperature of 190℃, an injection pressure of 30 MPa, and a screw speed of 359 r / min. The extruded granules are dried at 85℃ for 2 hours. Finally, a polypropylene composite material is obtained, with a density of 1.05 g / cm³. 3 .

[0083] Example 2

[0084] First, weigh the raw materials according to the following mass ratio: 30 parts of high crystallinity copolymer polypropylene, 25 parts of homopolymer polypropylene, 25 parts of glass fiber, 3 parts of toughening agent ethylene propylene diene monomer (EPDM), 0.2 parts of nucleating agent maleic anhydride 2, 0.1 parts of type 152 magnesium oxysulfate whiskers, 0.1 parts of antioxidant 1010, 0.1 parts of lubricant polyethylene wax, 0.1 parts of scratch resistant agent tetraboride, and 0.05 parts of light stabilizer 770 component.

[0085] Next, the raw materials are mixed evenly in a high-speed mixer, and then the mixture is added to an extruder for plasticizing and kneading. The fully kneaded melt enters a specially designed die head, through which continuous glass fibers also pass. Dispersion, wetting, and melt encapsulation are completed within the specially designed die head. Subsequently, under traction, the mixture is cooled, shaped, and cut through a die to form a blend, which is then extruded and granulated. The extruder is configured with an extrusion temperature of 200℃, a speed of 450 r / min, an injection temperature of 190℃, an injection pressure of 30 MPa, and a screw speed of 359 r / min. The extruded granules are dried at 85℃ for 2 hours. Finally, a polypropylene composite material is obtained, and its density is tested to be 1.03 g / cm³.

[0086] Example 3

[0087] First, weigh the raw materials according to the following mass ratio: 35 parts of high crystallinity copolymer polypropylene, 30 parts of homopolymer polypropylene, 30 parts of glass fiber, 5 parts of toughening agent ethylene propylene diene monomer (EPDM), 0.4 parts of nucleating agent maleic anhydride 3, 0.3 parts of type 152 magnesium oxysulfate whiskers, 0.3 parts of 1010 antioxidant, 0.3 parts of lubricant polyethylene wax, 0.3 parts of scratch resistant agent tetraboride, and 0.15 parts of light stabilizer 770 component.

[0088] Next, the raw materials are mixed evenly in a high-speed mixer, and then the mixture is added to an extruder for plasticizing and kneading. The fully kneaded melt enters a specially designed die head, where continuous glass fibers also pass through. Within the die head, dispersion, wetting, and melt encapsulation are completed. Subsequently, under traction, the mixture is cooled, shaped, and cut through a die to form a blend, which is then extruded and granulated. The extruder is configured with an extrusion temperature of 200℃, a speed of 450 r / min, an injection temperature of 190℃, an injection pressure of 30 MPa, and a screw speed of 359 r / min. The extruded granules are dried at 85℃ for 2 hours. Finally, a polypropylene composite material is obtained, and its density is tested to be 1.07 g / cm³.

[0089] Based on the analysis of the above embodiments, it is known that a traditional polypropylene composite material made by combining 30% glass fiber with polypropylene resin has a density of 1.15 g / cm³. However, the polypropylene composite material produced in the embodiments of this application has a density of 1.03 g / cm³. 3 -1.07g / cm 3 Their densities are all lower than those of traditional polypropylene composites. Therefore, the embodiments of this application can illustrate that the prepared novel glass fiber and polypropylene composite material has a lower density and lighter weight.

[0090] The following analysis, based on the above structural design, comprehensively examines the modal and strength stress parameters of the structure to determine whether its overall structure meets the design requirements.

[0091] Firstly, a comparative analysis of the structural modes was conducted to obtain the first-order mode shapes and frequencies. Analysis showed that the first-order mode of the traditional glass fiber reinforced polypropylene composite material was 33.09 Hz, while the first-order mode of the lightweight glass fiber reinforced polypropylene composite material produced in this application was 33.21 Hz, meeting the design requirement of ≥30 Hz. This indicates that the structure designed in this application, regardless of whether it uses traditional polypropylene composite materials or the polypropylene composite material provided in this application, can meet the first-order mode design requirements, demonstrating that the structural optimization of this application meets the design requirements.

[0092] The strength of the sub-instrument panel under simulated driving conditions was tested by applying accelerations in three directions to the sub-instrument panel system: a vertical impact load of -2.5g; a turning load of -1g, and a width x-load of +2g; and an emergency braking load of -1g in the height z-direction and -2g in the width x-direction. The required strength was ≤80MPa. Through testing and analysis under vertical, turning, and emergency braking conditions, the maximum stress obtained under vertical conditions was 3.8MPa; under turning conditions, the maximum stress was 2.3MPa; and under emergency braking conditions, the maximum stress was 5.8MPa. Based on these strength analysis results, it was found that the maximum stress value of 5.8MPa at the weakest point was significantly lower than the design requirement of ≤80MPa. This indicates that the selection of structural materials and structural optimization met the design requirements.

[0093] By optimizing material selection and structural design, product lightweighting can be achieved. Results show that the sub-instrument frame designed in this application, using the lightweight glass fiber reinforced polypropylene composite material provided in this application, achieves weight reductions of 13.02%, 10.03%, and 9.36% respectively compared to traditional glass fiber reinforced polypropylene composite materials, with an average weight reduction of over 11% for the entire assembly. For example, a traditional sub-instrument assembly made of conventional polypropylene composite materials weighs 2.45 kg, while the sub-instrument assembly made of the lightweight glass fiber reinforced polypropylene composite material of this application weighs only 2.2 kg. The weight reduction effect is 11.36%.

[0094] This application also provides a vehicle, which can be a gasoline car, diesel car, electric car, or other types of vehicle. For example, it can be an electric vehicle (EV), a pure electric vehicle / battery electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle. Including the injection-molded parts provided in this application, through material improvements, structural optimization, and process optimization, they can meet design and manufacturing requirements, achieving lightweight and strength design requirements, providing technical support for vehicle weight reduction, and can be widely used in commercial vehicles currently on the market.

[0095] It should be noted that the technical solutions or features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the accompanying drawings; all modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An injection-molded part for a vehicle auxiliary instrument assembly, characterized in that, The injection-molded part is made of a polypropylene composite material, which comprises at least the following components by weight: 30-35 parts of highly crystalline copolymer polypropylene; 25-30 parts of homopolymer polypropylene; 25-30 parts glass fiber; 3-5 parts toughening agent, 2-3 parts nucleating agent, 0.2-0.4 parts whiskers; The glass fiber has a specification of 2400 tex; in the step of integrally injection molding the molten polypropylene composite material into the injection molded part through an injection mold, the temperature of the injection mold is 50-60℃, the melt temperature is 230-240℃, the injection speed is 40-60mm / s, the back pressure is 165-170bar, and the holding pressure is 30-42MPa.

2. The injection-molded part for a vehicle auxiliary instrument assembly as described in claim 1, characterized in that, The polypropylene composite material further includes the following components in parts by weight: Antioxidant 0.1-0.3 parts, lubricant 0.1-0.3 parts, scratch resistant agent 0.1-0.3 parts, light stabilizer 0.05-0.15 parts.

3. The injection-molded part for a vehicle auxiliary instrument assembly as described in claim 2, characterized in that, The toughening agent is selected from one or more of ethylene propylene rubber (EPR), thermoplastic elastomer SEBS, and polyolefin elastomer (POE).

4. The injection-molded part for a vehicle sub-instrument assembly as described in any one of claims 1 to 3, characterized in that, The side of the injection molded part includes a first sidewall and a second sidewall disposed opposite to each other. The first sidewall is used to fix the parts inside the injection molded part. The surface of the first sidewall is provided with an outwardly protruding first reinforcing rib, and the first reinforcing rib is distributed in a polygonal shape. Along the height direction of the injection molded part, the first sidewall includes a first region, a second region and a third region arranged vertically in sequence. The number of parts fixed in the second region is greater than the number of parts fixed in the first region and greater than the number of parts fixed in the third region. The first reinforcing ribs in the first region are distributed in multiple first polygons, the first reinforcing ribs in the second region are distributed in multiple second polygons, and the first reinforcing ribs in the third region are distributed in multiple third polygons. The number of sides of the second polygons is greater than the number of sides of the first polygons and greater than the number of sides of the third polygons.

5. The injection-molded part for a vehicle auxiliary instrument assembly as described in claim 4, characterized in that, The surface of the second sidewall is provided with an outwardly protruding second reinforcing rib, which is distributed in multiple regular hexagons on the second sidewall.

6. The injection-molded part for a vehicle auxiliary instrument assembly as described in claim 4, characterized in that, The side of the injection molded part also includes a third sidewall, which connects the first sidewall and the second sidewall. The third sidewall has a drawer opening and a third reinforcing rib that extends toward the interior of the injection molded part. The cross-section of the third reinforcing rib is double H-shaped.

7. The injection-molded part for a vehicle auxiliary instrument assembly as described in claim 6, characterized in that, The injection molded part also includes a top wall, the three sides of which are respectively connected to the first side wall, the second side wall and the third side wall. Along the thickness direction of the injection molded part, the length of the top wall is less than the length of the first side wall. Along the thickness direction of the injection molded part, the first region includes a first sub-region and a second sub-region distributed side by side, and the side length of the top wall includes the side length of the first sub-region and part of the side length of the second sub-region. The reinforcing ribs of the first sub-region are distributed in multiple squares, and the reinforcing ribs of the second sub-region are distributed in multiple rectangles.

8. The injection-molded part for a vehicle sub-instrument assembly as described in claim 7, characterized in that, The top wall is provided with at least one first protrusion facing the interior of the injection molded part, and at least one second protrusion facing the exterior of the injection molded part; and / or The top wall has multiple weight-reducing holes.

9. A method for manufacturing an injection-molded part for a vehicle auxiliary instrument assembly, characterized in that, include: The raw materials are mixed to form a polypropylene composite material, wherein the raw materials include: 30-35 parts of highly crystalline copolymer polypropylene, 25-30 parts of homopolymer polypropylene, 25-30 parts of glass fiber, 3-5 parts of toughening agent, 2-3 parts of nucleating agent, 0.2-0.4 parts of whiskers, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of lubricant, 0.1-0.3 parts of scratch resistant agent, and 0.05-0.15 parts of light stabilizer, wherein the glass fiber has a specification of 2400 tex; The molten polypropylene composite material is integrally injection molded into the injection molded part using an injection mold; in the step of integrally injection molding the molten polypropylene composite material into the injection molded part using an injection mold, the temperature of the injection mold is 50-60℃, the melt temperature is 230-240℃, the injection speed is 40-60mm / s, the back pressure is 165-170bar, and the holding pressure is 30-42MPa.

10. A vehicle, characterized in that, Including the injection molded part as described in any one of claims 1 to 8.

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