Injection molding method for large-size metal part of automobile plastic tail door based on insert molding process

Abstract

The invention relates to an injection molding method for a large-size metal part of an automobile plastic tail door based on an insert molding process, which comprises the following steps: S1, molding a metal insert, and forming a plurality of flash holes and positioning holes in the molded metal insert, S2, putting the metal insert with the flash holes and the positioning holes into an insert molding mold, a positioning hole of the metal insert is formed in a positioning column of the insert forming mold, so that the metal insert is positioned in the insert forming mold; s3, long glass fiber toughened modified polypropylene used for forming the plastic inner plate through injection molding is injected into an insert forming mold with a metal insert, the long glass fiber toughened modified polypropylene wraps the metal insert and is formed on the metal insert through injection molding, and the long glass fiber toughened modified polypropylene flowing into the overflow hole serves as a rib after injection molding; the plastic tail door assembly has the advantages that the fitting degree between the metal insert and the plastic inner plate is enhanced, and the strength of the plastic tail door assembly is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of automobile plastic tailgates, and in particular to an injection molding method for a large-size metal part of an automobile plastic tailgate based on an insert molding process. Background Art

[0002] In order to comply with the global demand for reducing fuel consumption and the increasingly stringent emission regulations, lightweight products such as plastic tailgates are becoming more and more popular. Insert molding is a common production process for plastic tailgates. The bending amplitude of the plastic tailgate is increased by injection molding the metal insert inside the plastic inner panel. However, as the car models continue to grow, the size of the plastic tailgate of the vehicle is also increasing. However, the large-sized metal insert and the plastic inner panel will be impacted by the flow pressure during the injection molding process, making the two poorly fit. There is a risk of cracking during the experiment. This has also become a technical difficulty in insert injection molding of metal parts. In actual use, due to the different thermal expansion coefficients of metal and plastic, there is a risk of delamination and cracking between the metal insert and the plastic inner panel. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide an injection molding method for large-size metal parts of automobile plastic tailgates based on insert molding technology. During the design process of insert-molded metal parts, by adding overflow holes, the movement caused by flow pressure can be effectively solved, so that the metal parts and plastic inner panels have a higher fit and better compatibility during injection molding, and the risk of cracking between the metal and plastic inner panels is reduced, so as to overcome the above-mentioned shortcomings of the prior art.

[0004] The present invention provides an injection molding method for a large-size metal part of a plastic tailgate of an automobile based on an insert molding process, which specifically comprises the following steps:

[0005] Step S1: Forming of the metal insert, opening a plurality of overflow holes and positioning holes on the formed metal insert,

[0006] The overflow hole is opened on the horizontal end surface and side wall of the metal insert away from the curved surface, the fillet, and the step surface, that is, the opening position of the overflow hole should be maintained on the horizontal plane and the side wall to ensure that the flow of material passes through the metal part evenly, so that the plastic inner plate and the metal part are easier to fit;

[0007] Wherein, the positioning hole is opened at the edge of the metal insert, and a positioning column is arranged on the insert molding mold corresponding to the position of the positioning hole;

[0008] Step S2: placing the metal insert with the overflow hole and the positioning hole into the insert molding mold, wherein the positioning hole of the metal insert is mounted on the positioning column of the insert molding mold, so that the metal insert is positioned in the insert molding mold;

[0009] Step S3: injecting the long glass fiber reinforced modified polypropylene used for injection molding into the plastic inner panel into the insert molding mold with the metal insert, so that the long glass fiber reinforced modified polypropylene is coated and injection molded on the metal insert, wherein the long glass fiber reinforced modified polypropylene flowing into the overflow hole is used as ribs after injection molding, and the ribs in the multiple overflow holes and the plastic partitions injection molded on the surface of the metal insert constitute a plastic inner panel with mesh ribs.

[0010] As a preferred embodiment of the present invention, the overflow hole is a circular hole with a diameter of 3 mm to 4 mm.

[0011] As a preferred embodiment of the present invention, the plurality of overflow holes are arranged around the center of the contact surface between the metal insert and the plastic inner plate, and the overflow holes are also arranged on the side wall where the metal insert contacts the plastic inner plate.

[0012] The beneficial effects of the present invention are as follows: the metal insert is connected to the plastic inner panel by adding multiple ribs by opening overflow holes on the plane and the side wall, thereby enhancing the fit between the metal insert and the plastic inner panel and strengthening the strength of the plastic tailgate assembly, thereby solving the problem of cracking of the insert injection molded tailgate. In addition, the grid structure formed by the added multiple ribs can effectively solve the problem of delamination and cracking caused by the different thermal expansion coefficients of metal and plastic during actual use. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easy to understand. In the accompanying drawings:

[0014] Figure 1 Schematic diagram of the overall structure of the metal insert of this embodiment.

[0015] Figure 2 This is a front view of the overall structure of the metal insert in this embodiment.

[0016] Figure 3 It is a side view of the overall structure of the metal insert of this embodiment.

[0017] Figure 4 for Figure 3 AA section view.

[0018] The reference numerals include: metal insert 1, overflow hole 2 DETAILED DESCRIPTION

[0019] See also Figure 1-4 As shown, the present embodiment provides an injection molding method for a large-size metal part of a plastic tailgate of an automobile based on an insert molding process, which specifically includes the following steps:

[0020] Step S1: forming the metal insert 1, opening a plurality of overflow holes 2 and positioning holes on the formed metal insert 1,

[0021] The overflow hole 2 is opened on the horizontal end surface and side wall of the metal insert 1 away from the curved surface, fillet, and step surface, that is, the overflow hole 2 should avoid the fillet, the sharply changing curved surface, the step surface, and the surface with too small size of the metal insert 1, and be kept on the horizontal plane and the side wall to ensure that the flow of materials passes through the metal insert 1 evenly, so that the plastic inner plate and the metal insert 1 are easier to fit;

[0022] Among them, the positioning hole is opened at the edge of the metal insert 1, and a positioning column is set on the insert molding mold corresponding to the position of the positioning hole;

[0023] Step S2: placing the metal insert 1 with the overflow hole 2 and the positioning hole into the insert molding mold, wherein the positioning hole of the metal insert 1 is mounted on the positioning column of the insert molding mold, so that the metal insert 1 is positioned in the insert molding mold;

[0024] Step S3: injecting the long glass fiber reinforced modified polypropylene used for injection molding into the plastic inner panel into the insert molding mold with the metal insert 1, so that the long glass fiber reinforced modified polypropylene is coated and injection molded on the metal insert 1, wherein the long glass fiber reinforced modified polypropylene flowing into the overflow hole 2 is used as ribs after injection molding, and the ribs in the multiple overflow holes 2 and the plastic partitions injection molded on the surface of the metal insert 1 constitute a plastic inner panel with mesh ribs.

[0025] The overflow holes 2 in this embodiment are circular holes with a diameter of 3 mm to 4 mm, and the spacing between the circular holes is set to 30 mm to 50 mm; the opening positions of multiple overflow holes 2 are arranged around the center of the contact surface between the metal insert 1 and the plastic inner plate, and the overflow holes 2 are also arranged on the side wall where the metal insert 1 contacts the plastic inner plate.

[0026] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An injection molding method for large-size metal parts of automobile plastic tailgate based on insert molding process, characterized in that: The following steps are involved: Step S1: Forming of the metal insert, opening a plurality of overflow holes and positioning holes on the formed metal insert, The overflow hole is opened on the horizontal end surface and side wall of the metal insert away from the curved surface, the fillet, and the step surface, that is, the opening position of the overflow hole should be maintained on the horizontal plane and the side wall to ensure that the flow of material passes through the metal part evenly, so that the plastic inner plate and the metal part are easier to fit; Wherein, the positioning hole is opened at the edge of the metal insert, and a positioning column is arranged on the insert molding mold corresponding to the position of the positioning hole; Step S2: placing the metal insert with the overflow hole and the positioning hole into the insert molding mold, wherein the positioning hole of the metal insert is mounted on the positioning column of the insert molding mold, so that the metal insert is positioned in the insert molding mold; Step S3: injecting the long glass fiber reinforced modified polypropylene used for injection molding into the plastic inner panel into the insert molding mold with the metal insert, so that the long glass fiber reinforced modified polypropylene is coated and injection molded on the metal insert, wherein the long glass fiber reinforced modified polypropylene flowing into the overflow hole is used as ribs after injection molding, and the ribs in the multiple overflow holes and the plastic partitions injection molded on the surface of the metal insert constitute a plastic inner panel with mesh ribs.

2. The method for injection molding a large-size metal part of a plastic tailgate of an automobile based on an insert molding process according to claim 1, characterized in that: The overflow hole is a circular hole with a diameter of 3 mm to 4 mm.

3. The method for injection molding a large-size metal part of a plastic tailgate of an automobile based on an insert molding process according to claim 1, characterized in that: The opening positions of the plurality of overflow holes are arranged around the center of the contact surface between the metal insert and the plastic inner plate, and the overflow holes are also arranged on the side wall where the metal insert contacts the plastic inner plate.

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