CN116018253A

CN116018253A - Method for manufacturing a structural part of a motor vehicle, in particular a suspension arm, having a hollow cross section and made of a composite material, and suspension arm obtained by this method

Info

Publication number: CN116018253A
Application number: CN202180054198.XA
Authority: CN
Inventors: S·索蒂尔; A·圣蒂尼; M·戈亚
Original assignee: Marelli Suspension Systems Italy SpA
Current assignee: Marelli Suspension Systems Italy SpA
Priority date: 2020-09-07
Filing date: 2021-09-07
Publication date: 2023-04-25
Also published as: WO2022049558A1; EP4210974A1; IT202000021133A1

Abstract

A method for manufacturing a suspension arm (9) of an automotive suspension, comprising the step of preparing a composite prepreg material; shaping the composite prepreg by compression molding in a closed molding press to obtain two respective half-shells (10); -assembling the two half-shells (10) such that they form a core (12), defining a cavity (14) inside the core (12); preparing additional composite charges and placing them in the mold; the charge is shaped by compression molding in a closed molding press so that each half-shell (10) is completely covered by them, so that the half-shells produce an outer body (16) completely surrounding the core (12).

Description

Method for manufacturing a structural part of a motor vehicle, in particular a suspension arm, having a hollow cross section and made of a composite material, and suspension arm obtained by this method

Technical Field

The present invention relates generally to the field of automobiles; in particular, the invention relates to a method for manufacturing a structural part of a motor vehicle (in particular a suspension arm of a motor vehicle) having a hollow section made of a composite material, and to a suspension arm obtained by said method.

Prior Art

The suspension arm is an element of the motion system, implemented by the front suspension system or the rear suspension system of the vehicle.

Basically, the suspension arm has the function of carrying and connecting between the moving part of the vehicle (wheel strut, shock absorber system) and the fixed part (body, chassis, cross beam). The type of connection portion varies from architecture to architecture.

In the field of suspension structural components, more specifically in the field of components for automotive suspension arms, materials commonly used are cast iron, aluminum and steel according to well known processes such as sheet metal forming, forging and stamping in different configurations.

Technological innovations in the production of these components, as well as increasingly stringent requirements for reducing the weight of structural suspension components, have led to increasingly frequent shifts to single-shell or double-shell profiled sheet metal product configurations, depending on the final performance required at the vehicle level.

Therefore, for metal parts with hollow cross-sections, it is necessary to perform continuous process flows, such as continuous welding and spot welding, and related design constraints (size of the fins, accessibility of the welding torch, etc.).

In order to make the parts lighter, composite materials, which are generally processed by pultrusion, have been widely used in the automotive industry.

However, in the case of hollow parts having a complex shape, such as suspension arms, pultrusion is unsuitable, and thus the prior art does not consider solutions for manufacturing structural parts of motor vehicles (such as, in particular, suspension arms), which improve the characteristics in terms of weight and flexibility while preserving the shape and function of the traditional metal parts.

It will be appreciated that these limitations impair the possibility of having more high performance components relative to known arrangements.

Disclosure of Invention

It is an object of the present invention to overcome the above problems.

To this end, the structural components of the vehicle, such as suspension arms, suspension struts, chassis beams, etc., are made of composite filler, which is shaped by compression molding in a closed molding press to form (at least) two half shells that, once assembled, will define the interior cavity of the final component. The hollow core formed by the two assembled half shells is then placed in a mold, the final geometry is made by overmolding in a closed molding press using a composite filler material that will fill all of its cavities once the mold is closed, creating a body with the final geometry of the part.

At the end of this process, the hollow core is then sealed in one integral piece and shaped according to the geometry of the final part.

Due to this construction, the structural component according to the invention made of composite material having a hollow cross-section is lighter relative to corresponding conventional steel, aluminum or cast iron components, while maintaining its properties.

The two (or more) inner shells form the hollow core of the component and are made using well known compression molding processes in a closed molding press.

The material considered is a fiber reinforced composite which may be continuous (unidirectional fibers or fabrics with different balances and/or directions), discontinuous or mixed (hybrid structures, including continuous fiber laminates unidirectional or balanced according to the stacking sequence, reinforced by common mode ribs made of discontinuous fibers depending on the mechanical properties to be achieved).

The resin may be thermosetting or thermoplastic.

According to the compression molding technique described above in closed molding presses (known per se), the two half-shells constituting the cavity can then be made of continuous fibers (for example glass fibers, carbon, basalt, aramid), discontinuous fibers with continuous fiber reinforcement, or vice versa.

The inner surfaces of the two half-shells forming the hollow core may be provided with a system of ribs adapted to increase the deformation resistance of the hollow core.

The hollow core is made by assembling two half shells. Assembly may be accomplished by known techniques of geometric attachment, continuous attachment (e.g., adhesive or friction welding), or discontinuous attachment by insertion of metal inserts (e.g., nails or rivets). The seat of the insert may be co-molded directly into the surface of the two (or more) half-shells, thereby forming a cavity. The adhesion at the polymer/metal interface can be improved chemically according to known surface activation techniques, or mechanically according to the prior art by making the appropriate geometry or by appropriate treatments or machining.

The final geometry is achieved by subsequent over-molding of the hollow core and the reinforced composite material according to known compression molding techniques in closed molding presses. The adhesion between the outer surface of the cavity and the filling material, which is conveniently cured after firing in a hot mold or in a cold mold (depending on the type of material matrix and thus on the type of compression molding in a closed molding press), can be improved mechanically (for example by special geometry and/or surface treatments such as sandblasting), chemically (for example by laser surface activation techniques) or by inserting a third medium (for example an adhesive of known type).

During the over-molding of the outer body on the hollow core, co-molding of the metal inserts may be provided, which may form corresponding seats for bushings, ball joints, etc., to allow subsequent connection of the components to the various components of the vehicle.

According to one aspect of the present invention, the above and other objects and advantages are achieved by a method for manufacturing a structural part of a motor vehicle, in particular an automotive suspension arm, having a hollow section made of a composite material, and by a suspension arm obtained by said method, having the characteristics defined in the appended claims.

Brief description of the drawings

The functional and structural features and implementation of the manufacturing method and suspension arm according to some preferred embodiments of the present invention will now be described. Referring to the drawings, wherein:

fig. 1 is a schematic perspective view of a structural component of a motor vehicle, in particular an automotive suspension arm, according to one embodiment of the invention;

fig. 2 and 3 are a schematic perspective view and an exploded view, respectively, of a hollow core embedded within the suspension arm of fig. 1, according to one embodiment of the invention;

figures 4 and 5 are two schematic perspective views of a portion of the outer body of the half-shell surrounding the core, respectively in the absence and presence of stiffening ribs associated with the half-shell, according to one embodiment of the invention; and

fig. 6 to 8 are respectively a perspective view of the suspension arm in the assembled state of the outer body and the hollow core, a partial section of the arm of fig. 6 (in which the inner body is visible) and a partial section of the arm of fig. 6 (in which the inner body fitted with reinforcing ribs can be seen), according to two respective embodiments of the invention.

Detailed Description

Before describing in detail embodiments of the invention, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. It is also to be understood that the phraseology and terminology is for the purpose of description and should not be regarded as limiting.

Furthermore, the following description will mainly relate to the manufacture of arms for automotive suspensions. However, it should be understood that the method according to the invention is generally applicable to any structural component of a motor vehicle, which is itself suitable for manufacturing by the claimed process (e.g. struts of an automotive suspension, cross-beams of a chassis, etc.) due to its geometrical, mechanical and/or functional characteristics.

A method for manufacturing a structural part of a motor vehicle having a hollow cross section made of a composite material, comprising the step of preparing prepreg fibres made of a composite material. These materials are of the type conventionally referred to as "prepregs" and may initially be in the form of plates, sheets, or fillers that are generally of semi-solid or pasty consistency.

Subsequently, the composite prepreg is formed by compression molding in a closed molding press, whereby two respective half-shells 10 are obtained. Basically, the material is loaded into a mould and under the pressure exerted by the press (according to the well known compression moulding technique in a closed moulding press) the material will flow inside the mould until the desired shape is embossed, in this case in one half-shell.

The two half-shells 10 are then assembled, whereby these mutually facing half-shells 10 form a core 12, defining a cavity 14 inside this core 12.

Additional composite filler is then prepared and placed in the mold.

The coating charge is shaped by molding in a closed molding press such that each half shell 10 is completely covered by them, whereby the coating charge creates an outer shell 16 completely surrounding the core 12.

According to a preferred embodiment, the above method is configured to obtain a structural component in the form of an automotive suspension arm.

Conveniently, the composite material used to make the half-shells 10 and/or to make the outer body 16 comprises a thermoplastic or thermosetting resin matrix.

Preferably, the composite material used to make the half shell 10 and/or to make the outer body 16 is a material selected from the group consisting of sheet molding compound ("SMC"), advanced sheet molding compound ("a-SMC"), glass fiber sheet molding compound ("GFSMC"), carbon fiber sheet molding compound ("CFSMC"), and bulk molding compound ("BMC"). These composite materials are well known to those skilled in the art.

According to one embodiment, the step of coupling the half-shells 10 to each other is performed by gluing or friction welding the edge of one half-shell 10 to the other half-shell 10.

According to an alternative embodiment, the step of coupling the half-shells 10 to each other in step (c) is performed by stapling or riveting the edges of the half-shells 10 to each other.

It is also possible to provide a step of arranging a plurality of metal inserts 18, suitable for housing parts of the sleeve and/or ball joint, and a step of moulding the outer body 16 and said metal inserts 18.

According to one embodiment, the method comprises the step of applying a rib 20 to one or both half-shells 10, said rib 20 being adapted to impart greater resistance to deformation (e.g. greater bending and/or torsional stiffness) to the half-shells 10 and/or to act as a support for the inner core 12 during the step of over-moulding the outer body 16 to prevent deformation or collapse of the core 12). The ribs 20 extend within the cavity 14 and may be configured as a lattice of lamellae extending between the inner walls of the hollow core 12.

According to one aspect of the invention, a suspension arm 9 for an automotive suspension is obtained by a method according to any of the embodiments of the method described above, said suspension arm 9 comprising a core 12 made of composite material and hollow inside, said core 12 being incorporated into an outer body 16, made of composite material and comprising a plurality of seats 17, which seats 17 are adapted to house means for connecting said suspension arm 9 to a vehicle.

Various aspects and embodiments of a method for manufacturing an automotive component and a suspension arm obtained by such a method according to the invention have been described. It should be understood that each embodiment may be combined with any of the other embodiments. Furthermore, the invention is not limited to the described embodiments, but may be varied within the scope defined by the accompanying claims.

Claims

1. A method for manufacturing a suspension arm (9) of an automotive suspension, comprising the steps of:

a) Providing a prepreg of the composite material;

b) By compression molding in a closed molding press, the prepreg of the composite material is shaped in such a way as to obtain two respective half-shells (10);

c) Assembling the two half-shells (10) such that the two opposite half-shells (10) form a core (12), defining a cavity (14) inside said core (12);

d) Providing additional coating charges of composite material and placing them in a mold;

e) By compression molding in a closed molding press, the coating charge is shaped in such a way that each half-shell (10) is completely covered by the coating charge, so that the coating charge produces an outer body (16) completely surrounding the core (12).

2. The method of claim 1, wherein the composite material of step (a) and/or step (d) comprises a thermoplastic or thermoset resin matrix.

3. The method according to claim 1 or 2, characterized in that the composite material of step (a) and/or step (d) is a material selected from the group comprising Sheet Molding Compound (SMC), advanced sheet molding compound (a-SMC), glass Fiber Sheet Molding Compound (GFSMC), carbon Fiber Sheet Molding Compound (CFSMC) and Bulk Molding Compound (BMC).

4. Method according to any one of the preceding claims, characterized in that step (c) is performed by gluing or friction welding the edge of one half-shell (10) to the other half-shell (10).

5. A method according to any one of claims 1 to 3, characterized in that step (c) is performed by mutually stapling or riveting the edges of the half shells (10).

6. The method according to any one of the preceding claims, comprising the step of providing a plurality of metal inserts (18), the metal inserts (18) being adapted to receive portions of a sleeve and/or a ball joint, and the step of co-moulding an outer body (16) and the ball joint.

7. The method according to any one of the preceding claims, further comprising the step of applying a rib (20) to one or both of the half-shells (10), said rib being adapted to impart greater resistance to deformation to said half-shells (10), said rib (20) extending into the cavity (14).

8. Suspension arm (9) for an automotive suspension, obtained by the method according to any one of the preceding claims, the suspension arm (9) comprising a core (12) made of composite material and hollow inside, the core (12) being contained in an outer body (16), made of composite material and comprising a plurality of seats (17), the seats (17) being suitable for housing means for connecting the suspension arm (9) to a vehicle.