A mold for embedding pre-embedded parts in composite sandwich components

Abstract

This invention discloses a mold for embedding a pre-embedded part in a composite sandwich component, comprising: an upper mold, a lower mold, and a steel insert; both the upper and lower molds are made of aluminum alloy, forming a cavity between them when the molds are closed; the bottom surface of the upper mold has a first mounting hole, and the lower mold is embedded with at least one steel insert, the top surface of which has a second mounting hole; the center lines of the first and second mounting holes are on the same straight line and are both located inside the cavity; the first mounting hole is used to insert the bottom end of the pre-embedded part, and the second mounting hole is used to form a boss covering the top end of the pre-embedded part. The steel insert is used to contact the pre-embedded part to withstand wear during the molding process, while the lower and upper molds only contact the relatively soft composite sandwich component, thereby reducing the mold's production cycle and cost, and extending the mold's service life.

Description

Technical Field

[0001] This invention relates to the field of molds, and more specifically to a mold for embedding pre-embedded parts in composite sandwich components. Background Technology

[0002] The technical field disclosed in this invention relates to "embedding pre-embedded parts in composite sandwich components" and is disclosed in CN116811298A: a method for molding pre-embedded nuts as an integral composite material and a mold.

[0003] Currently, people want to press pre-embedded nuts, bolts, or pre-embedded nut connectors into a composite sandwich structure consisting of three layers. The upper and lower layers of the composite sandwich structure are made of black 400g fabric prepreg with excellent mechanical properties, and the middle layer is made of epoxy SMC prepreg.

[0004] Methods for pressing pre-embedded nuts, bolts, or pre-embedded nut connectors into the material include: in-mold embedding, ultrasonic embedding, hot melt embedding, press-fit embedding, and self-tapping embedding.

[0005] Since the composite sandwich component is composed of three layers of materials, each with different mechanical properties and coefficients of thermal expansion, it is not suitable for ultrasonic embedding, hot melt embedding, press-fit embedding, and self-tapping embedding. Furthermore, the fabric prepreg cannot be formed by injection molding. Therefore, none of the above five methods are suitable for pressing pre-embedded nuts, bolts, or pre-embedded nut connectors into the composite sandwich component composed of three layers.

[0006] CN116811298A discloses a molding method different from the five methods mentioned above. This method relies on a specially made steel mold or aluminum mold. Pure steel molds are not suitable for sample production with short R&D cycles due to their high cost, long processing cycle, and complex internal structure. Pure aluminum molds are not suitable for mold production due to their soft material properties. When molding pre-embedded nuts, bolts, etc., the nuts and bolts are hard and the aluminum mold will soften after heating, so there is a risk of mold damage. Summary of the Invention

[0007] The purpose of this invention is to provide a mold for embedding pre-embedded parts in composite sandwich components, so as to solve the technical problems of high price of steel mold and short life of aluminum mold in molds for integrally molding composite sandwich components with pre-embedded parts.

[0008] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0009] A mold for embedding a pre-embedded part in a composite sandwich component includes: an upper mold, a lower mold, and a steel insert; both the upper mold and the lower mold are made of aluminum alloy, and a cavity is formed between the upper mold and the lower mold when the mold is closed; the bottom surface of the upper mold is provided with a first mounting hole, and at least one of the steel inserts is embeddedly mounted in the lower mold, and the top surface of the steel insert is provided with a second mounting hole; the center lines of the first mounting hole and the second mounting hole are located on the same straight line and are both located inside the cavity; the first mounting hole is used to insert the bottom end of the pre-embedded part, and the second mounting hole is used to form a boss covering the top end of the pre-embedded part.

[0010] Furthermore, the top surface of the lower mold is provided with a blind hole, the steel insert is embedded inside the blind hole, and an intermediate insert is provided between the lower mold and the steel insert, the coefficient of thermal expansion of the intermediate insert being between that of the lower mold and the steel insert.

[0011] Furthermore, when the steel insert, the intermediate insert, and the lower mold are heated to the temperature of the molded composite sandwich part, they can fit together. The steel insert is made of 45 steel, and the intermediate insert is made of 304 stainless steel.

[0012] Furthermore, at least two fasteners are connected to the steel insert through the bottom wall of the lower mold, so that the steel insert cannot rotate in the blind hole.

[0013] In another aspect of the invention, the top surface of the lower mold is provided with a blind hole. Both the blind hole and the steel insert are frustum-shaped with their upper bases facing the upper mold. The axial length of the blind hole is greater than the axial length of the steel insert. The steel insert is connected to the lower mold via a driving device. The driving device is used to lift the steel insert upward when the lower mold and the steel insert are heated to the temperature of the molded composite sandwich part, so that the conical surface of the blind hole matches the conical surface of the steel insert, and the top surface of the steel insert is flush with the wall surface of the mold cavity of the lower mold. The driving device is used to drag the steel insert downward before the lower mold and the steel insert cool, so that the conical surface of the blind hole separates from the conical surface of the steel insert.

[0014] Furthermore, the driving device includes: hydraulic oil; the hydraulic oil fills the cavity between the blind hole and the steel insert, and a seal is installed on the steel insert or the lower mold to seal the gap between the conical surface of the steel insert and the conical surface of the blind hole.

[0015] Furthermore, the lower mold includes a first template and a second template. The first template has a tapered through hole, and the second template fits against the bottom surface of the first template and covers the through hole to form the blind hole.

[0016] Furthermore, the second template is provided with an oil hole that communicates with the interior of the blind hole. The hydraulic oil is injected into the cavity between the blind hole and the steel insert through the oil hole, and the oil hole is sealed by a sealing plug.

[0017] Furthermore, the driving device includes: a fastener and an elastic element; the fastener passes through the second template and is threadedly connected to the steel insert, the fastener includes a guide portion, the second template is provided with a guide hole, the guide hole is slidably connected to the guide portion and the connection part is sealed; the end of the fastener away from the second template is provided with an actuating portion extending radially outward, the elastic element is installed between the actuating portion and the second template, the elastic element is used to generate a spring force that causes the actuating portion to move away from the second template.

[0018] Furthermore, at least two of the fasteners are connected to the steel insert through the bottom wall of the lower mold, so that the steel insert cannot rotate in the blind hole.

[0019] Compared with the prior art, this application has the following advantages:

[0020] A mold for embedding pre-embedded parts in a composite sandwich component is provided. A steel insert is used to contact the pre-embedded parts to withstand wear during the molding process. The lower mold and the upper mold only contact the relatively soft composite sandwich component, thereby reducing the production cycle and cost of the mold and extending the service life of the mold. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the internal structure of Embodiment 1 of the present invention;

[0023] Figure 2 This is a schematic diagram of one working condition of Embodiment 2 of the present invention, showing the internal structure of the mold in the heating state;

[0024] Figure 3 This is a schematic diagram of another working condition of Embodiment 2 of the present invention, showing the internal structure of the mold in a cooling state;

[0025] The labels in the diagram represent the following:

[0026] 1-Upper mold; 11-First mounting hole; 2-Lower mold; 21-Blind hole; 22-First template; 221-Through hole; 23-Second template; 231-Oil hole; 232-Oil plug; 233-Guide hole; 3-Steel insert; 31-Second mounting hole; 4-Cavity; 5-Intermediate insert; 6-Drive device; 61-Hydraulic oil; 62-Sealing ring; 63-Fastener; 631-Guide part; 632-Actuating part; 64-Disc spring. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In molds used for integrally molding composite sandwich parts with embedded parts, there are technical problems such as the high price of steel molds and the short life of aluminum molds. To solve this problem, a method and mold are provided below.

[0029] The mold includes: upper mold 1, lower mold 2, and steel insert 3;

[0030] Both the upper mold 1 and the lower mold 2 are made of aluminum alloy. When the molds are closed, a cavity 4 is formed between the upper mold 1 and the lower mold 2.

[0031] The bottom surface of the upper mold 1 is provided with a first mounting hole 11, and the lower mold 2 is fitted with at least one steel insert 3, the top surface of the steel insert 3 is provided with a second mounting hole 31;

[0032] The center lines of the first mounting hole 11 and the second mounting hole 31 are on the same straight line and are both located inside the cavity 4;

[0033] The first mounting hole 11 is used to insert the bottom end of the embedded part, and the second mounting hole 31 is used to form a boss covering the top end of the embedded part.

[0034] The text omits common mold structures such as mold frames. The edge of cavity 4 is provided with overflow channels and overflow ports. The steel insert 3 is made of 45 steel. The lower mold 2 and upper mold 1 are made of 6061, 6063 or 7075 aluminum alloy. The steel insert 3 is used to contact the embedded parts to withstand the wear during the molding process. The lower mold 2 and upper mold 1 only contact the relatively soft composite sandwich parts, thereby extending the service life of the mold.

[0035] The problem with the above technical solution is:

[0036] The coefficients of thermal expansion of 45 steel and aluminum alloy are different. The coefficient of thermal expansion of 45 steel is approximately 12 x 10^-6 / ℃, that of 6061 aluminum alloy is approximately 23.6 x 10^-6 / ℃, and that of 7075 aluminum alloy is approximately 23.2 x 10^-6 / ℃.

[0037] Molded composite sandwich parts require a certain high temperature. After the mold is heated, a gap will be generated between the lower mold 2 and the steel insert 3. The composite sandwich parts will flow into the gap during the molding process. After the mold is opened, corresponding burrs will be generated on the surface of the composite sandwich parts, affecting the surface quality of the composite sandwich parts.

[0038] If the steel insert 3 and the lower mold 2 are designed in advance to fit together when heated to the molding temperature, a large internal stress will be generated between the steel insert 3 and the lower mold 2 when the mold is cooled, which can easily lead to damage to the lower mold 2.

[0039] To address the aforementioned technical issues, two technical solutions are presented below.

[0040] Example 1, please refer to Figure 1 .

[0041] An intermediate insert 5 is provided between the lower mold 2 and the steel insert 3. The coefficient of thermal expansion of the intermediate insert 5 is between that of 45 steel and aluminum alloy and is close to the average of the two.

[0042] The intermediate insert 5 is made of 304 stainless steel, which has a coefficient of thermal expansion of 17×10^-6 / ℃. After assembling the lower mold 2 and the steel insert 3, molten 304 stainless steel is poured into the gap between the lower mold 2 and the steel insert 3. After it cools, the connection between the three parts is polished.

[0043] When the lower mold 2 and the steel insert 3 are heated and expand, the intermediate insert 5 is also heated and expands. The expansion degree of 304 stainless steel is between that of aluminum alloy and No. 45 steel. If the steel insert 3, the intermediate insert 5 and the lower mold 2 are designed in advance to fit together when heated to the molding temperature, the internal stress between the steel insert 3 and the lower mold 2 is dispersed to the intermediate insert 5 when the mold is cooled, which can prevent the lower mold 2 from being damaged to a certain extent.

[0044] To minimize stress concentration points between the lower mold 2, the intermediate insert 5, and the steel insert 3, the steel insert 3 is designed as a cylinder, and the intermediate insert 5 is a ring-shaped piece fitted around the outside of the steel insert 3. This makes the hole in the lower mold 2 for inserting the steel insert 3 a circular hole, thereby reducing stress concentration points.

[0045] However, the problem with this solution is that the second mounting hole 31 is a regular hexagonal prism shape, which is directional. In order to facilitate the insertion of the embedded part into the second mounting hole 31, the direction of each second mounting hole 31 needs to be consistent. Therefore, it is necessary to prevent the steel insert 3 from rotating in the lower mold 2 before casting the intermediate insert 5.

[0046] To solve the above technical problems: a blind hole 21 is provided on the top surface of the lower mold 2, and a steel insert 3 is installed inside the blind hole 21. At least two bolts pass through the bottom wall of the lower mold 2 to connect the steel insert 3 so that the steel insert 3 cannot rotate in the blind hole 21.

[0047] The image only shows one bolt for illustration.

[0048] Example 2, please refer to Figure 2 and Figure 3 .

[0049] The top surface of the lower mold 2 is provided with a blind hole 21. Both the blind hole 21 and the steel insert 3 are frustum-shaped and their upper bottoms face the upper mold 1. The axial length of the blind hole 21 is greater than the axial length of the steel insert 3. The steel insert 3 is connected to the lower mold 2 through the drive device 6.

[0050] When the lower mold 2 and the steel insert 3 are at the molding temperature, the driving device 6 is used to lift the steel insert 3 upward so that the conical surface of the blind hole 21 matches the conical surface of the steel insert 3, and the top surface of the steel insert 3 is flush with the wall surface of the mold cavity of the lower mold 2.

[0051] Before the lower mold 2 and the steel insert 3 cool down, the drive device 6 is used to drag the steel insert 3 downward so that the conical surface of the blind hole 21 and the conical surface of the steel insert 3 are separated.

[0052] The drive device 6 can be a threaded rod, jack, hydraulic cylinder or other instruments. The drive device 6 is used to pre-separate the lower mold 2 and the steel insert 3 before they cool, so that a gap sufficient for them to make complementary contact when they shrink is generated, thereby avoiding the generation of internal stress between them that is sufficient to cause deformation of the aluminum alloy.

[0053] Furthermore, in order to reduce the burden on staff, reduce operating steps and equipment costs, a preferred technical solution is provided below to enable the drive device 6 to operate automatically at different temperatures.

[0054] Drive unit 6 includes: hydraulic oil 61;

[0055] Hydraulic oil 61 fills the interior of blind hole 21 and contacts the bottom surface of steel insert 3. A sealing ring 62 is installed on steel insert 3 or lower mold 2 to seal the gap between the conical surface of steel insert 3 and the conical surface of blind hole 21.

[0056] The coefficient of thermal expansion of hydraulic oil 61 is much higher than that of aluminum alloy and 45 steel. When the mold is heated, the hydraulic oil 61 expands and generates a thrust that lifts the steel insert 3 so that it matches the blind hole 21.

[0057] Specifically, hydraulic oil 61 is filled by the following method:

[0058] The lower mold 2 includes a first template 22 and a second template 23. The first template 22 is provided with a tapered through hole 221. The second template 23 fits against the bottom surface of the first template 22 and covers the through hole 221 to form a blind hole 21. The second template 23 is provided with an oil hole 231 that communicates with the inside of the blind hole 21. Hydraulic oil 61 is injected into the inside of the blind hole 21 through the oil hole 231. The oil hole 231 is sealed by an oil plug 232.

[0059] Furthermore, during mold cooling, the steel insert 3 is separated from the blind hole 21 by the following method:

[0060] Fastener 63 passes through the second template 23 and is threadedly connected to the steel insert 3. Fastener 63 includes a guide portion 631. The second template 23 is provided with a guide hole 233. The guide hole 233 is slidably connected to the guide portion 631 and the connection part is sealed. The end of the fastener 63 away from the second template 23 is provided with an actuating portion 632 extending radially outward. Several disc springs 64 are installed between the actuating portion 632 and the second template 23.

[0061] When the mold cools down, the volume of hydraulic oil 61 decreases, the steel insert 3 loses its upward lifting force, and the disc spring 64 pushes the actuator 632 downward through its own elasticity, so that the fastener 63 drags the steel insert 3 downward.

[0062] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A mold for embedding pre-embedded parts in a composite sandwich component, characterized in that, include: Upper mold (1), lower mold (2) and steel insert (3); Both the upper mold (1) and the lower mold (2) are made of aluminum alloy. When the mold is closed, a cavity (4) is formed between the upper mold (1) and the lower mold (2). The bottom surface of the upper mold (1) is provided with a first mounting hole (11), and the lower mold (2) is embeddedly fitted with at least one of the steel inserts (3), and the top surface of the steel insert (3) is provided with a second mounting hole (31). The center lines of the first mounting hole (11) and the second mounting hole (31) are on the same straight line and are both located inside the cavity (4); The first mounting hole (11) is used to insert the bottom end of the embedded part, and the second mounting hole (31) is used to form a boss covering the top end of the embedded part; The top surface of the lower mold (2) is provided with a blind hole (21). The blind hole (21) and the steel insert (3) are both frustum-shaped and their upper bottoms face the upper mold (1). The axial length of the blind hole (21) is greater than the axial length of the steel insert (3). The steel insert (3) is connected to the lower mold (2) through a drive device (6). The drive device (6) is used to lift the steel insert (3) upward when the lower mold (2) and the steel insert (3) are heated to the temperature of the molded composite sandwich part, so that the conical surface of the blind hole (21) matches the conical surface of the steel insert (3), and the top surface of the steel insert (3) is flush with the wall surface of the mold cavity of the lower mold (2); The drive device (6) is used to drag the steel insert (3) downward before the lower mold (2) and the steel insert (3) are cooled, so that the conical surface of the blind hole (21) and the conical surface of the steel insert (3) are separated.

2. The mold for embedding pre-embedded parts in a composite sandwich component according to claim 1, characterized in that, The top surface of the lower mold (2) is provided with a blind hole (21), and the steel insert (3) is embedded inside the blind hole (21). An intermediate insert (5) is provided between the lower mold (2) and the steel insert (3), and the coefficient of thermal expansion of the intermediate insert (5) is between that of the lower mold (2) and the steel insert (3).

3. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 2, characterized in that, When the steel insert (3), the intermediate insert (5) and the lower mold (2) are heated to the temperature of the molded composite sandwich part, they can fit together. The steel insert (3) is made of No. 45 steel, and the intermediate insert (5) is made of 304 stainless steel.

4. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 2, characterized in that, At least two fasteners are connected to the steel insert (3) through the bottom wall of the lower mold (2) so that the steel insert (3) cannot rotate in the blind hole (21).

5. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 1, characterized in that, The drive device (6) includes: hydraulic oil (61); The hydraulic oil (61) fills the cavity between the blind hole (21) and the steel insert (3), and a seal is installed on the steel insert (3) or the lower mold (2) to seal the gap between the conical surface of the steel insert (3) and the conical surface of the blind hole (21).

6. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 5, characterized in that, The lower mold (2) includes a first template (22) and a second template (23). The first template (22) is provided with a tapered through hole (221). The second template (23) fits against the bottom surface of the first template (22) and covers the through hole (221) to form the blind hole (21).

7. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 6, characterized in that, The second template (23) is provided with an oil hole (231) that connects to the inside of the blind hole (21). The hydraulic oil (61) is injected into the cavity between the blind hole (21) and the steel insert (3) through the oil hole (231). The oil hole (231) is sealed by a sealing plug.

8. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 6, characterized in that, The drive device (6) includes: a fastener (63) and an elastic element; The fastener (63) passes through the second template (23) and is threadedly connected to the steel insert (3). The fastener (63) includes a guide portion (631). The second template (23) is provided with a guide hole (233). The guide hole (233) is slidably connected to the guide portion (631) and the connection part is sealed. The fastener (63) has an actuating part (632) extending radially outward at one end away from the second template (23). The elastic element is installed between the actuating part (632) and the second template (23) and is used to generate an elastic force that causes the actuating part (632) to move away from the second template (23).

9. A mold for embedding pre-embedded parts in a composite sandwich component according to claim 8, characterized in that, At least two of the fasteners (63) are connected to the steel insert (3) through the bottom wall of the lower mold (2) so that the steel insert (3) cannot rotate in the blind hole (21).

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