A method for preparing a composite lightweight auxiliary frame of an automobile and the product thereof

Abstract

A kind of automobile composite material light weight subframe preparation method and product, adopt the structure of glass fiber cloth being set outside foam inner core as the body structure of subframe, adopt metal connecting piece as the connecting component of subframe and outside, and metal connecting piece includes metal insert and metal assembly;The specific preparation method of subframe is as follows: first, the corresponding metal connecting piece is designed according to the connection requirement of subframe, then the foam inner core is processed into the preliminary shape of subframe, and the metal insert is set to the foam inner core to form solid frame;Then glass fiber cloth is set outside solid frame, and composite material body is formed;Finally, after heating and solidification of composite material body in mould, metal assembly is set on composite material body after cooling and finishing, and complete subframe is formed.The formed subframe has foam, glass fiber and metal three kinds of materials, so resonance does not occur due to the vibration of a certain frequency of vehicle, and the NVH performance of vehicle can be effectively improved, to bring better use experience to user.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method and an article of a subframe, in particular to a preparation method and an article of a composite material lightweight subframe of an automobile, and belongs to the technical field of lightweight technology of new energy vehicles. BACKGROUND

[0002] As an important part of an automobile suspension, a subframe is responsible for connecting important parts such as a vehicle body, a power assembly, a steering machine, a stabilizer bar and a control arm, and has been widely applied to the field of passenger vehicles. The existing subframe structure is generally an integral cast aluminum alloy subframe and a split type welded subframe. In order to ensure the connection stability and the connection strength, the structure is relatively complex and more redundant materials are used for structural reinforcement, but this can greatly increase the overall weight of the subframe, and the aluminum alloy subframe has low qualification rate, large casting deformation, increased probability of sand eye, shrinkage and porosity, high cost and is not conducive to the development of vehicle lightweight. With the rapid development of new energy vehicles, the requirement for lightweight of an automobile chassis is increasingly urgent. For example, the application for a manufacturing method of a lightweight composite material subframe of an automobile, with the publication number CN116198145A and the name "a manufacturing method of a lightweight composite material subframe of an automobile", discloses a method of first fixing a plurality of winding end points with a tool, then winding a continuous fiber along the winding end points into a ring-shaped reinforcing body, then forming a composite material on the reinforcing body to form a ring-shaped structure surrounded by a plurality of cross beams, and finally pressing the cross beams into ball hinges to form a subframe. Although the product formed by this method can meet the use requirements in performance and weight, the process requirement is high. SUMMARY

[0003] The application proposes a preparation method and an article of a composite material lightweight subframe of an automobile, which adopts the method of laying glass fiber cloth as a framework outside a foam inner core and setting metal connecting pieces on the framework to prepare a subframe with three different materials, so as to effectively improve the NVH performance of the vehicle.

[0004] The technical scheme adopted by the present application to solve the above problems is as follows: a preparation method of a composite lightweight auxiliary frame of an automobile, which adopts a structure of a foam inner core outside which is provided with glass fiber cloth as the body structure of the auxiliary frame, and adopts a metal connecting piece as the connecting component of the auxiliary frame and the outside, and the metal connecting piece comprises a metal insert and a metal assembly; the specific preparation method of the auxiliary frame is as follows: firstly, a corresponding metal connecting piece is designed according to the connection requirements of the auxiliary frame; then, the foam inner core is processed into a preliminary shape of the auxiliary frame, and the metal insert is arranged on the foam inner core to form a solid frame; then, the glass fiber cloth is arranged outside the solid frame to form a composite body; finally, the composite body is placed in a mold and heated and solidified, and after cooling and finishing, the metal assembly is arranged on the composite body to form a complete auxiliary frame. The formed auxiliary frame integrally combines the foam, the glass fiber and the metal together, which can effectively improve the NVH performance of the vehicle while meeting the requirements of lightweight and strength.

[0005] Further, the foam inner core is formed by numerical control machining technology to ensure the accuracy of the size.

[0006] Further, the position where the metal insert is arranged on the foam inner core is provided with a recess hole, and the metal insert is adhered in the recess hole by an adhesive. The recess hole cooperates with the adhesive to better fix the metal insert.

[0007] Further, the glass fiber cloth is a glass fiber woven cloth prepreg with a resin matrix of epoxy resin, and the weaving mode is 0° / 90°, and the thickness of each layer of the prepreg is 0.5 mm.

[0008] Further, when the glass fiber cloth is laid, it is first laid on the upper, lower, inner and outer four surfaces of the solid frame, and then the upper, lower, inner and outer four surfaces are wound. The separately laid glass fiber cloth is wound into a whole by winding.

[0009] Further, after the glass fiber cloth is laid on each surface for seven layers, it is wound for two layers.

[0010] Further, when the glass fiber cloth is laid, the entire solid frame is divided into eight segments along the circumference, each segment is laid separately, and the adjacent two segments are laid in a staggered lap joint manner. Each segment is laid separately to ensure the flatness of the segment, and the staggered lap joint laying ensures the connection strength.

[0011] Further, the metal insert is provided with a threaded hole, the connecting part of the metal insert is wrapped in the glass fiber cloth after the glass fiber cloth is laid, and the threaded hole is communicated with the outside. The stability of the metal insert is ensured.

[0012] Further, the metal assembly is provided with a threaded hole, which is adhered to the outer surface of the composite body by an adhesive, and a bolt is further provided to pass through the threaded hole and the threaded hole to lock and fix the metal assembly. The stability of the metal assembly is ensured by the adhesive and the bolt locking.

[0013] Further, the mold comprises an upper mold, an outer core mold, an inner core mold and a bottom mold, the inner core mold is matched with the inner structure of the composite body, the outer core mold is matched with the outer structure of the composite body, the upper mold is matched with the top structure of the composite body, the bottom mold is matched with the bottom structure of the composite body, the inner core mold and the outer core mold clamp the composite body when heated and cured, and the upper mold and the bottom mold clamp the composite body from top to bottom.

[0014] Further, the mold further comprises positioning bolts, the outer core mold and the inner core mold are further provided with positioning holes, the positions of the positioning holes correspond to the positions of the threaded holes of the metal inserts when the composite body is placed in the mold, and the positioning bolts are locked with the outer core mold and the inner core mold by extending into the positioning holes and the threaded holes.

[0015] Further, the mold further comprises plugging bolts, the upper mold and the bottom mold are further provided with avoiding holes, the positions of the avoiding holes correspond to the positions of the threaded holes of the metal inserts when the composite body is placed in the mold, and the plugging bolts are locked with the threaded holes and then extend into the avoiding holes.

[0016] Further, when heated and cured, the composite body, the inner core mold, the outer core mold and the bottom mold are first combined into an integral whole, the integral whole is sealed by a vacuum bag film, vacuumizing and heating are performed, the vacuum bag film is removed after the glass fiber cloth is softened, then the inner core mold and the outer core mold are locked by the positioning bolts, the upper mold is covered, the integral whole is sealed by the vacuum bag film, vacuumizing and heating are performed.

[0017] The automobile composite lightweight auxiliary frame product comprises a composite body formed by a foam inner core and glass fiber cloth laid outside the foam inner core, and supports the main body of the auxiliary frame, and a whole formed by a metal insert embedded in the composite body and a metal component fixed outside the composite body by being connected with the metal insert as a connecting structure outside the auxiliary frame.

[0018] The beneficial effects of the present application are:

[0019] 1. The present application first processes the foam inner core into the shape of the auxiliary frame, and then lays the fiber cloth by taking the foam inner core as the support, so that no additional tooling is needed as the support for laying the fiber cloth, the process is more mature and stable, and after the auxiliary frame is prepared, the foam inner core is still retained in the auxiliary frame, which can play a better damping role.

[0020] 2. The present application adopts numerical control machining to form the foam inner core, and the metal insert and the metal component are fastened by the way of glue joint and mechanical connection, so that the product size precision can be effectively controlled.

[0021] 3. The present application ensures the connection strength by adopting metal connecting pieces for the structure of the sub-frame connected with the outside, and divides the metal connecting pieces into metal inserts and metal assemblies, the metal inserts are fixed in the recesses of the foam inner core, and then the connection positions of the metal inserts are wrapped with fiber cloth to ensure the stability of the metal inserts; the metal assemblies which cannot be wrapped with fiber cloth are bolted with partial metal inserts, which can ensure the stability of the metal assemblies.

[0022] 4. The present application divides the heating and curing operation into two steps, does not lock the cover during the first heating, locks the cover after the glass fiber cloth is softened, makes the inner core mold and the outer core mold be clamped more tightly, and the prepared sub-frame has higher size precision, and part of air in the composite body can be discharged during the first heating process, which further improves the quality of the prepared sub-frame. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structure schematic diagram of the sub-frame product of the embodiment one;

[0024] Figure 2 It is a structure schematic diagram of the sub-frame product of the embodiment one; Figure 1 It is a schematic diagram of separating the metal assemblies from the composite body;

[0025] Figure 3 It is a structure schematic diagram of the composite body of the embodiment one;

[0026] Figure 4 It is a structure schematic diagram of the solid frame of the embodiment one;

[0027] Figure 5 It is a structure schematic diagram of the metal inserts of the embodiment one;

[0028] Figure 6 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0029] Figure 7 It is a structure schematic diagram of the foam inner core of the embodiment one; Figure 8 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0030] Figure 9 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0031] Figure 10 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0032] Figure 11 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0033] Figure 12 It is a structure schematic diagram of the foam inner core of the embodiment one; Figure 11 It is a structure schematic diagram of the foam inner core of the embodiment one;

[0034] Figure 13 Figure 1 is a schematic diagram of the bottom die structure of Example 1;

[0035] Figure 14 Figure 2 is a schematic diagram of the inner core die and outer core die of Example 1;

[0036] Figure 15 Figure 3 is a schematic diagram of the inner core die structure of Example 1;

[0037] Figure 16 Figure 4 is a schematic diagram of the outer core die structure of Example 1;

[0038] Figure 17 Figure 5 is a schematic diagram of the upper die structure of Example 1;

[0039] Figure 18 Figure 6 is a schematic diagram of the solid frame being divided into eight segments of Example 1, wherein the structure of the recess and the metal insert is omitted in the figure;

[0040] In the figure: 1. Foam inner core, 11. Recess, 2. Solid frame, 3. Composite material body, 4. Metal insert, 41. Threaded hole, 45. Connection hole, 5. Metal assembly, 51. Screw hole, 6. Mold, 61. Upper die, 62. Inner core die, 63. Outer core die, 64. Bottom die, 65. Positioning bolt, 66. Blocking bolt, 67. Positioning hole, 68. Avoidance hole. DETAILED DESCRIPTION

[0041] The application will be further described below in conjunction with the accompanying drawings. In the drawings, only exemplary illustrations are shown, and only schematic diagrams are represented, which cannot be understood as a limitation of the patent; in order to better illustrate the embodiments of the application, some components in the drawings will be omitted, enlarged or reduced, and do not represent the actual size of the product; it can be understood by those skilled in the art that some well-known structures in the drawings and their descriptions can be omitted. Example 1

[0042] A preparation method of a composite material lightweight auxiliary frame of an automobile, as shown in Figure 1 , the prepared auxiliary frame product comprises a composite material body 3 in the shape of a whole ring and a metal assembly 5 arranged on the composite material body 3, wherein a metal insert 4 is also embedded in the composite material body 3, and the metal insert 4 and the metal assembly 5 together constitute a metal connecting piece for connecting the auxiliary frame and the outside.

[0043] In order to meet the strength requirements of the auxiliary frame under the premise of meeting the lightweight requirements of the automobile, the composite material body 3 is prepared by laying glass fiber cloth outside the foam inner core 1, as shown in Figure 2 、 Figure 5 、 Figures 7-9As shown, the structure for connecting with the outside adopts metal connectors to ensure the connection strength, and the metal connectors are divided into metal inserts 4 and metal assemblies 5, the metal inserts 4 are designed to be embedded into the composite material body 3, and only the connection surface is connected with the outside, while the metal assemblies 5 are structures that protrude from the surface of the composite material body 3 and are not easy to be embedded into the composite material body 3. In order to ensure that the metal assemblies 5 can be stably arranged on the composite material body 3, threaded holes 41 are arranged on part of the metal inserts 4, and screw holes 51 are arranged on the metal assemblies 5, and after the screw holes 51 are locked with the threaded holes 41 through bolts, the metal assemblies 5 can be fixed. At the same time, the metal assemblies 5 and part of the metal inserts 4 are both provided with connecting holes 45 as the connecting structure of the subframe, that is, the metal assemblies 5 are all used for connecting with the outside, while part of the metal inserts 4 are used for connecting with the outside, and part of the metal inserts 4 are used as the intermediate structure for fixing the metal assemblies 5 on the composite material body 3, and part of the metal inserts 4 are used for both connecting with the outside and fixing the metal assemblies 5, at this time, the same metal insert 4 has both threaded holes 41 and connecting holes 45. The specific preparation method of the subframe is as follows:

[0044] First step: as shown in Figure 2 and Figure 5 , the corresponding metal inserts 4 and metal assemblies 5 are designed according to the connection requirements required for installing the subframe on the vehicle, to ensure that all the connection structures are embodied on the metal assemblies 5 or the metal inserts 4, and metal inserts 4 for locking connection with the metal assemblies 5 are also designed. The metal inserts 4 and the metal assemblies 5 are designed with connecting holes for connecting with the vehicle, the metal inserts 4 are also provided with threaded holes 41 for connecting with the metal assemblies 5, the metal assemblies 5 are provided with corresponding screw holes 51 for connecting with the metal inserts 4, and the metal inserts 4 also need to be designed to have structures such as steps, staggered layers, or bosses, to facilitate their formation into structures embedded in the formed subframe in subsequent processing.

[0045] Second step: as shown in Figure 6 , the PET material is processed into a foam inner core 1 with the overall frame shape of the subframe by using numerical control processing technology, and the foam inner core 1 is provided with recessed holes 11 for placing the metal inserts 4, and the positions and shapes of the recessed holes 11 need to match the corresponding metal inserts 4. Then, as shown in Figure 4 , the metal inserts 4 are adhered in the corresponding recessed holes 11 to form a solid frame 2, to provide shape support for subsequent operations without the need for additional tooling.

[0046] Step 3: A 0.5mm thick, 0° / 90° fiberglass woven fabric prepreg (referred to as fiberglass cloth) with an epoxy resin matrix is ​​laid on the outside of the subframe 2. Because the exterior of the subframe 2 is uneven, laying a single piece of fiberglass cloth on its entire outer surface at once will inevitably result in numerous wrinkles, affecting the subframe's performance. Therefore, during installation, if… Figure 18 As shown, the entire frame 2 is first divided into eight sections circumferentially. The fiberglass cloth is then cut to the size required for each section's outer surface. Seven layers of the cut fiberglass cloth are then laid on the upper, lower, inner, and outer surfaces of each section of the frame 2. Finally, strips of fiberglass cloth are wrapped around the entire outer surface of the frame 2. After two layers of wrapping, the composite material body 3 is formed. And as... Figure 3 As shown, in the composite material body 3, only the connecting surface of the metal insert 4 is open to the outside, while the other surfaces are wrapped in fiberglass cloth to form an embedded structure. The metal insert 4 is fixed in the composite material body 3 by a combination of adhesive bonding and fiberglass cloth wrapping to ensure the stability of the metal insert 4.

[0047] Step 4: Place the composite material body 3 into the mold 6 and heat it to cure. This step will be described in detail later in conjunction with the mold structure.

[0048] Step 5: Remove excess flash from the demolded composite material body 3, grind the right-angled edges to the specified rounded corners, and check whether resin has entered the threaded holes 41 and connecting holes 45 of each metal insert 4. After cleaning, roughen the bonding surface of the threaded holes 41 of the metal insert 4 used to connect with the metal components 5, and use adhesive to bond each metal component 5 to the corresponding position. Press and use bolts to lock the corresponding threaded holes 51 and threaded holes 41, and clean off excess adhesive. The preparation of the subframe is now complete.

[0049] like Figure 10 As shown, the mold 6 used in the fourth step includes an upper mold 61, an inner core mold 62, an outer core mold 63, a bottom mold 64, positioning bolts 65, and sealing bolts 66. Figures 13-17As shown, the upper mold 61, inner core mold 62, outer core mold 63, and bottom mold 64 are respectively in contact with the upper surface, inner surface, outer surface, and lower surface of the composite material body 3. The inner core mold 62 and outer core mold 63 are provided with positioning holes 67, and the upper mold 61 and bottom mold 64 are provided with clearance holes 68. When the composite material body 3 is installed into the mold 6, the positions of the positioning holes 67 and clearance holes 68 correspond to the positions of the threaded holes 41 or connecting holes 45 of the metal insert 4. The positioning bolts 65 extend into the positioning holes 67 and the threaded holes 41 or connecting holes 45 to position the inner core mold 62 and outer core mold 63, while the sealing bolts 66 extend into the clearance holes 68 and the threaded holes 41 or connecting holes 45 to prevent resin from entering the holes.

[0050] During heat curing, the composite material body 3 is assembled into Figure 12 The inner core mold 62, outer core mold 63, and bottom mold 64 are sealed with vacuum bags. After vacuuming, the molds are placed in an autoclave for preheating for a period of time. Once the prepreg has softened and a certain volume of air has been expelled, the vacuum bags are removed. The inner core mold 62 and outer core mold 63 are then locked together using positioning bolts 65. Heating for a period of time to soften the composite material body 3 before locking and heating ensures a tighter bond between the inner core mold 62 and outer core mold 63, thus guaranteeing higher dimensional accuracy of the molded subframe. The remaining threaded holes 41 and connecting holes 45 are plugged using sealing bolts 66 (of course, sealing bolts 66 may also be installed before heating, depending on the situation). The entire assembly is then placed back into the vacuum bag, vacuumed, and placed in an autoclave for heating and pressure curing. After completion, the vacuum bags are removed, the upper mold 61 is opened, and the positioning bolts 65 and sealing bolts 66 are removed to demold the composite material body 3.

[0051] The following is combined with Figures 7-9 The fixing of the metal insert 4 and the metal component 5 is described in detail.

[0052] like Figure 7 The diagram shows the fixing of the metal component 5 in A', using two metal inserts 4 from A and A0 for fixing. First, as shown in A1, corresponding recesses 11 of the aforementioned two metal inserts 4 are set at the corresponding positions of the foam core 1; then, as shown in A2, the two metal inserts 4 are respectively glued to the corresponding recesses 11, and fiberglass cloth is laid and then wrapped to form the structure in A3; finally, the aforementioned metal component 5 is glued together and bolted to the two metal inserts 4, thus completing the fixing of this metal component 5.

[0053] like Figure 8The diagram shows the fixing of the metal component 5 in B', using two metal inserts 4 from B and B0 for fixing. First, as shown in B1, two recesses 11 of the corresponding shape of the aforementioned metal inserts 4 are set at the corresponding positions of the foam core 1; then, as shown in B2, the two metal inserts 4 are respectively glued into the two recesses 11, and fiberglass cloth is laid and wrapped around them successively, as shown in B3; finally, the metal component 5 is glued and bolted to the two metal inserts 4, thus completing the fixing of this metal component 5.

[0054] The above Figure 7 and Figure 8 The metal inserts 4 in the middle are all used as intermediate connectors to fix the metal components 5.

[0055] like Figure 9 The diagram shows the fixing of the metal insert 4 in C. The metal insert 4 has connecting holes 45 at both the top and bottom. First, as shown in C1, a recessed hole 11 is set at the corresponding position of the foam core 1. The recessed hole 11 is a countersunk through hole. Then, as shown in C2, the metal insert 4 is glued into the recessed hole 11. Finally, fiberglass cloth is laid and then wrapped around it to form the shape shown in C3.

[0056] The subframe product prepared in the above manner uses a very lightweight foam core 1 as the shaping structure for laying fiberglass cloth, uses fiberglass cloth as the supporting skeleton, and uses metal inserts 4 and metal components 5 as external connectors, which meets the requirements of lightweight while ensuring performance.

[0057] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the invention, which should be defined by the claims.

Claims

1. A method for preparing a lightweight automotive composite subframe, characterized in that: The structure of the body of the subframe is provided with a glass fiber cloth outside a foam inner core (1), a metal connecting piece is used as a connecting component of the subframe and the outside, and the metal connecting piece comprises a metal insert (4) and a metal assembly (5); the specific preparation method of the subframe is as follows: firstly, a corresponding metal connecting piece is designed according to the connection requirements of the subframe; then, the foam inner core (1) is processed into a preliminary shape of the subframe, the metal insert (4) is arranged on the foam inner core (1) to form a solid frame (2); then, the glass fiber cloth is arranged outside the solid frame (2) to form a composite material body (3); finally, the composite material body (3) is placed in a mold (6) for heating and curing, the metal assembly (5) is arranged on the composite material body (3) after cooling and finishing, and a complete subframe is formed. When the glass fiber cloth is laid, the glass fiber cloth is laid on the upper surface, the lower surface, the inner surface and the outer surface of the solid frame (2) respectively, and then the upper surface, the lower surface, the inner surface and the outer surface are wound. When the glass fiber cloth is laid, the entire solid frame (2) is divided into eight segments along the circumference, and each segment is laid separately, and the adjacent two segments are laid with a staggered lap joint. The metal insert (4) is provided with a threaded hole (41), the connecting part of the metal insert (4) is wrapped in the glass fiber cloth after the glass fiber cloth is laid, and the threaded hole (41) is communicated with the outside. The metal assembly (5) is provided with a threaded hole (51) and is adhered to the outer surface of the composite material body (3) by an adhesive, and is further provided with a bolt passing through the threaded hole (51) and the threaded hole (41) to lock and fix the metal assembly (5). The mold (6) comprises an upper mold (61), an outer core mold (63), an inner core mold (62) and a bottom mold (64), the outer peripheral structure of the inner core mold (62) is matched with the internal structure of the composite material body (3), the internal structure of the outer core mold (63) is matched with the outer peripheral structure of the composite material body (3), the bottom structure of the upper mold (61) is matched with the top structure of the composite material body (3), the top structure of the bottom mold (64) is matched with the bottom structure of the composite material body (3), and the inner core mold (62) and the outer core mold (63) clamp the composite material body (3) inside and outside when heating and curing, and the upper mold (61) and the bottom mold (64) clamp the composite material body (3) upward and downward.

2. The method of claim 1, wherein the method further comprises: The position where the metal insert (4) is arranged on the foam inner core (1) is provided with a recess (11), and the metal insert (4) is adhered to the recess (11) by an adhesive. ​ 3. The method of claim 1, wherein the method further comprises: The glass fiber cloth uses a glass fiber woven cloth prepreg with an epoxy resin as a resin matrix, the weaving method is 0° / 90°, and the thickness of each layer of the prepreg is 0.5 mm. ​ 4. The method of claim 1, wherein the method further comprises: The mold (6) further comprises a positioning bolt (65), and the outer core mold (63) and the inner core mold (62) are further provided with positioning holes (67); when the composite material body (3) is placed in the mold (6), the positions of the positioning holes (67) correspond to the positions of the threaded holes (41) of the metal insert (4), and the positioning bolt (65) is inserted into the positioning holes (67) and the threaded holes (41) to lock the outer core mold (63) and the inner core mold (62). ​ 5. The method for preparing a composite lightweight subframe of an automobile according to claim 4, characterized in that: In the heating and curing, first, the composite material body (3), the inner core mold (62), the outer core mold (63) and the bottom mold (64) are combined into a whole, the vacuum bag film is used to seal the whole, vacuum is drawn and heated, after the glass fiber cloth is softened, the vacuum bag film is removed; then the inner core mold (62) and the outer core mold (63) are locked by the positioning bolt (65), the upper mold (61) is covered, the vacuum bag film is used to seal and vacuum is drawn, and heating and curing are performed.

6. An automotive composite light weight sub-frame article prepared by the method of claim 1, characterized by: The whole is formed by the composite material body (3) formed by the foam inner core (1) and the glass fiber cloth laid outside the foam inner core (1) as the main body of the subframe, and the metal assembly (5) embedded in the metal insert (4) of the composite material body (3) and fixed outside the composite material body (3) by being connected with the metal insert (4) as the connecting structure outside the subframe.

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