CN110901076B - Assembly of subcomponents by compression molding - Google Patents

Abstract

A thermoplastic composite part assembly and a method of manufacturing the thermoplastic composite part assembly are disclosed. The thermoplastic composite part assembly is manufactured by: a molding step is first performed to form individual component features as discrete component feature parts, and a first compression molding step is used to separately form thermoplastic composite parts. A reprocessing step is then performed in which the discrete component feature components are integrated with the thermoplastic composite component using a second compression molding step. The reprocessing step essentially "welds" the discrete component feature components to the thermoplastic composite component at each of a plurality of desired component feature locations.

Description

Assembly of sub-components by compression molding

technical field

The present invention relates generally to the field of thermoplastic compounds. More specifically, the present invention relates to the assembly of thermoplastic composite subcomponents by a compression molding process to produce fully functional or cosmetic parts.

Background technique

Thermoforming is the manufacturing process of heating a thermoformable material to a temperature sufficient to allow the heated thermoformable material to be molded, such as by injection molding, and cooled into a final shape. An advantage of manufacturing using thermoformable materials is that they can be processed using heat.

Thermoformable composites are a combination of fiber reinforcement and resin matrix. The resin matrix can be thermoset or thermoplastic. A thermoplastic composite is a combination of a thermoplastic material (known as a thermoplastic resin or a thermoplastic resin matrix) and a reinforcing material such as individual fibers or fabrics made of fibers. Exemplary fiber materials include, but are not limited to, carbon, glass, aramid, polyester, jute, cellulose, and cotton. An exemplary thermoplastic compound is a continuous fiber reinforced thermoplastic (CFRT). Thermoplastic materials, including thermoplastic composites, may be reshaped or reprocessed after the materials have been set. Exemplary thermoplastic materials include, but are not limited to, polycarbonate (PC), formable PET (polyethylene terephthalate), polyamide, polyphenylene sulfide, polyether ketone, and ether ketone. A thermoset composite is a combination of a thermoset material (called a thermoset resin or a thermoset resin matrix) and a reinforcement material. Thermoset materials, including thermoset composites, cannot be reshaped after curing, even after heating. Exemplary thermoset materials include, but are not limited to, polyesters and epoxies.

In many applications, it is desirable to manufacture subassemblies, which are assemblies of thermoformed composite parts and additional parts. Assembly of such components can be accomplished by adhesive bonding or mechanical joints. In the case of thermoset composites, once a thermoset composite part is formed, further processing, such as bonding to another part, is difficult. Thermoset composites can be used to make integral component features for mechanical joints because thermoset resins are low viscosity liquids that work well to wet the complex 3D fibers necessary to form such mechanical joints in thermoset composite parts reinforcements. Examples of such assembly features include, but are not limited to, studs, fasteners, or threaded inserts. Although it is effective to integrally form assembly features on thermoset composite parts, thermosets have longer cycle times, fewer material options, and higher costs than thermoplastics. As a result, thermoplastic materials and thermoset composite parts have become more popular. However, with thermoplastic materials, it is difficult to use the 3D fiber reinforcement necessary to form integral component features on thermoplastic composite parts. In particular, it is difficult to manufacture integral assembly features, such as protruding studs, using normal compression molding processes used in the manufacture of thermoplastic composite parts. To make it feasible to mechanically join a thermoplastic composite part with another part, a threaded hole can be formed in the thermoplastic composite part, but sometimes the hole can disrupt the surface continuity of the fiber reinforcement and also create a weak point in the thermoplastic composite part. To attach assembly features, such as studs, fasteners, or threaded inserts, to thermoplastic composite parts, it is not as easy as simply drilling holes. Several methods have been developed to attach assembly features to thermoplastic composite parts.

Since the thermoplastic composite may be reprocessed, such as overmolded, after the thermoplastic composite part is formed, assembly features may be added after the thermoplastic composite part is formed. For example, after the thermoplastic compound is formed, an overmolding process may be performed to add assembly features. One conventional method for adding assembly features to an already formed thermoplastic composite part is to add each new assembly feature individually at each new assembly feature location using an injection molding process. A mold for each new assembly feature is positioned against the thermoplastic composite part at each of the assembly feature locations, and injection molding material is injection molded into each mold bonded to the thermoplastic composite part. However, in applications where many new component features are to be added, this can be a very time consuming and inefficient process. Another conventional method for adding new assembly features to an already formed thermoplastic composite part is to place the formed thermoplastic composite part into a tool and then perform a back injection molding process to form any desired assembly features. A disadvantage of this back injection molding process is the large amount of wasted material required to form the assembly features, which also adds to the weight of the thermoplastic composite part.

The back injection molding process is a form of injection molding. The thermoplastic composite part is formed with a back injection molded input opening and a channel network each of locations extending from the single input opening onto the thermoplastic composite part in which the assembly features will be formed. There is an output opening in the thermoplastic composite part at each assembly feature location. A large mold with multiple individual molds, one for each assembly feature and aligned with the corresponding output opening in the thermoplastic composite part, is positioned over the thermoplastic composite part. Injection molding material is injection molded into the input opening and distributed through channels to each of the output openings, where the injection molding material is injection molded into each individual mould. Injection molding material injected into each individual mold forms one of the assembly features. However, the injection molding material present in the channel extending from the input opening to the output opening is wasted material. The farther component features are spaced from each other, the more injection molding material is wasted.

Other conventional methods for adding assembly features to thermoplastic composite parts have been developed. EP0903216A2 discloses the overmoulding of a steel insert with claws which can be anchored in a thermoplastic composite part. In US 6682675 B1, a co-molding process of thermoplastic material and thermoplastic sandwich material is disclosed. A molded article can be easily attached to another article such as a vehicle body. In US 8197624 B2, a welding process is disclosed. This process joins thermoplastic polymer and thermoset polymer composite parts with thermoplastic surface layers by using high-frequency vibrations. In US 9180681 B2 a cylindrical insert with circumferential grooves is molded in thermoplastic composite compression molding, the grooves surrounded by the thermoplastic compound form a mechanical interlock to retain the insert in the thermoplastic compound. In US 9302434 B2 thermoplastic prepreg sheets are used to make composite parts with molded inserts. In US 9586362B2 a thermoplastic welding device is disclosed which uses an induction coil and at least one smart sensor. In US 9610654B1 a method and apparatus for joining thermoplastic composite parts using conformal induction coils embedded in a plurality of elastomeric sheets is disclosed. In US 9770892 B2 a device for welding two thermoplastic composite parts together is disclosed which uses a double-sided inductor and field absorber.

Typically, conventional methods of manufacturing thermoplastic composite parts with assembly features first manufacture the thermoplastic composite part and then perform an overmolding process to add the assembly features. While there are many different ways to attach the different features of an assembly, there is no conventional method for direct attachment of nuts or screws using compression molding.

Contents of the invention

Embodiments relate to a thermoplastic composite part assembly and methods of making the thermoplastic composite part assembly. A thermoplastic composite component assembly is manufactured by first performing a molding step to form individual assembly features as discrete assembly feature components and forming the thermoplastic composite component separately using a first compression molding step. Then, a reprocessing step is performed in which the discrete assembly feature parts are integrated with the thermoplastic composite part using a second compression molding step. The reprocessing step substantially "welds" the discrete assembly feature parts to the thermoplastic composite part at each of the desired assembly feature locations. This eliminates the need to add each component feature individually through a site-specific injection molding process, and eliminates wasted material associated with back injection molding processes.

In one aspect, a method of making a thermoplastic composite part assembly is disclosed. The method includes fabricating a discrete assembly feature part, fabricating a discrete thermoplastic composite part, aligning the assembly feature part with an assembly feature site on the thermoplastic composite part, and applying heat and compression to place the assembly feature at the assembly feature site. A feature component is bonded to the thermoplastic composite component to form the thermoplastic composite component assembly. In some embodiments, manufacturing the thermoplastic composite part includes performing a compression molding process on the thermoplastic composite material. In some embodiments, the compression molding process includes applying heat and compression to the thermoplastic composite. In some embodiments, the thermoplastic composite part has a molded shape. In some embodiments, the thermoplastic composite part includes a plurality of thermoplastic composite layers, and manufacturing the thermoplastic composite part further includes performing a pre-consolidation process to form laminated thermoplastic composite layers, and performing the compression molding process includes A compression molding process is performed on the pressed thermoplastic composite layer to form the thermoplastic composite part. In some embodiments, each thermoplastic composite layer includes thermoplastic material and fiber reinforcement. In some embodiments, applying heat and compression includes applying a compression molding process. In some embodiments, the assembly feature part includes a thermoplastic layer at a distal end, and aligning the assembly feature part with the assembly feature site on the thermoplastic composite part includes placing The thermoplastic layer at the end is placed against the thermoplastic composite part, and the compression molding process is applied to melt the thermoplastic layer to bond the distal end of the assembly feature part with the thermoplastic composite part at the assembly feature site . In some embodiments, the assembly feature part includes one of a stud, a fastener, or a threaded insert. In some embodiments, the assembly feature includes a threaded insert, and the threaded insert includes a threaded insert and a thermoplastic layer coupled to the threaded insert. In some embodiments, the threaded insert has a threaded hole exposed at the first end of the threaded insert, and the thermoplastic layer forms a cap over the second end of the threaded insert . In some embodiments, the cap of the threaded insert is positioned against the thermoplastic composite part, and heat and pressure are applied to melt the cap to bond with the thermoplastic composite part at the assembly feature site. In some embodiments, the method further includes manufacturing a plurality of the discrete assembly feature parts, aligning each of the plurality of assembly feature parts with corresponding assembly feature locations on the thermoplastic composite part, and applying heat and Compressing to bond each of the plurality of assembly feature parts to the thermoplastic composite part at each of the respective assembly feature locations. In some embodiments, applying heat and compression includes applying a compression molding process to simultaneously bond each of the plurality of assembly feature parts to the thermoplastic composite part at each of the respective assembly feature locations. In some embodiments, aligning each of the plurality of assembly feature parts with corresponding assembly feature locations on the thermoplastic composite part includes positioning each of the plurality of assembly feature parts on a compression molding tool and positioning the thermoplastic composite part in a holding position in the compression molding tool.

In another aspect, a thermoplastic composite part assembly is disclosed. The thermoplastic composite part assembly includes a thermoplastic composite part and a thermoplastic composite part compression molded onto the thermoplastic composite part. In some embodiments, the thermoplastic composite part has a molded shape. In some embodiments, the thermoplastic composite part includes a plurality of thermoplastic composite layers laminated together. In some embodiments, the assembly feature part includes a thermoplastic layer at a distal end, and the thermoplastic layer at the distal end of the assembly feature part is bonded to the thermoplastic composite part at the assembly feature site . In some embodiments, the assembly feature part includes one of a stud, a fastener, or a threaded insert.

Description of drawings

Several exemplary embodiments are described with reference to the drawings, wherein like parts have like reference numerals. The exemplary embodiments are intended to illustrate the invention, not to limit the invention. The accompanying drawings include the following figures:

FIG. 1 illustrates an exemplary manufacturing process for manufacturing a thermoplastic composite part assembly, according to some embodiments.

Figure 2 shows a cutaway side view of a molded threaded insert.

Figure 3 shows a cutaway side view of a molded threaded insert bonded to a thermoplastic composite part.

Detailed ways

Embodiments of the present application relate to a thermoplastic composite part assembly and method of manufacture. Those of ordinary skill in the art will appreciate that the following detailed description of thermoplastic composite component assemblies and methods of manufacture are illustrative only and are not intended to be limiting in any way. Other embodiments of thermoplastic composite component assemblies and methods of manufacture will readily occur to those having the benefit of this disclosure.

Reference will now be made in detail to implementations of thermoplastic composite component assemblies and methods of manufacture as illustrated in the accompanying drawings. The same reference designators will be used throughout the drawings and the following detailed description to refer to the same or like parts. In the interest of clarity, not all routine features of the implementations described herein are shown and described. Of course, it should be understood that in the development of any such actual implementation, many implementation-specific decisions must be made to achieve the developer's specific goals, such as adherence to application and business-related constraints, and that these specific goals may be in a Implementations vary from implementation to implementation and from one developer to another. Furthermore, it should be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine engineering undertaking for those of ordinary skill in the art having the benefit of this disclosure.

Thermoplastic composite component assembly 30 includes one or more assembly features integrally formed with thermoplastic composite component 12 , although the one or more assembly features and thermoplastic composite component 12 are initially manufactured separately as discrete components. Assembly features are mounting features that enable thermoplastic composite component assembly 30 to be assembled, mounted, connected, bonded, attached, or similarly coupled (collectively "assembled") to another discrete component having complementary assembly features .

During the fabrication process used to fabricate thermoplastic composite component assembly 30 , discrete assembly feature components are fabricated separately from fabrication of thermoplastic composite component 12 . The separately manufactured assembly feature parts are then integrally combined with the thermoplastic composite part 12 using a compression molding process. FIG. 1 illustrates an exemplary manufacturing process for manufacturing thermoplastic composite component assembly 30 in accordance with some embodiments. The thermoplastic composite part 12 may be manufactured using one or more discrete thermoplastic composite layers 2, 4 combined together. Each thermoplastic composite layer 2, 4 is a combination of thermoplastic material and reinforcement material of the type previously described. In the exemplary process shown in Figure 1, N thermoplastic composite layers 2, 4 are used. In some embodiments, each thermoplastic composite layer 2, 4 is made of fabric-thermoplastic prepreg (fibrous reinforcement in the form of a fabric) or unidirectional thermoplastic prepreg (made of individual fibers aligned in a single direction made of fiber reinforcements).

In step 6, the N thermoplastic composite layers 2 , 4 are laminated together by pre-consolidation to form a laminated thermoplastic composite layer 8 . During pre-consolidation all the layers 2, 4 of the composite are not completely pressed together, they just form a loosely attached pre-form for ease of handling during compression. In some embodiments, heat and pressure are used for lamination to bond the N thermoplastic composite layers 2, 4 together. At step 10, a first compression molding process is performed on the laminated thermoplastic composite layer 8 using a first compression molding tool at a suitable pressure and temperature to form a thermoplastic composite part 12 having a molded shape. Pressure is controlled by the molding tool and associated machinery, and temperature is a function of composite material properties. In some embodiments, the first compression molding tool is a different tool than the tool used for the lamination performed in step 6 . The discrete assembly feature parts are manufactured separately from the manufacturing of the thermoplastic composite part 12 . In the exemplary embodiment, one or more of the assembly feature components are molded threaded inserts 20 . The description that follows is based on this molded threaded insert 20 . It should be understood that alternative types of assembly feature components, such as studs, fasteners, or other types of threaded inserts 20 may be manufactured and used. The molded threaded insert 20 may be produced by first obtaining the threaded insert part 14 and then overmolding the threaded insert part 14 with the thermoplastic layer 18 , such as by using an injection molding process at step 16 . It should be understood that an alternative conventional overmolding process may be used to form the thermoplastic layer 18 over the threaded insert part 14 . The result is a molded threaded insert 20, shown as an assembly feature part.

FIG. 2 shows a cutaway side view of the molded threaded insert 20 . An overmolded thermoplastic layer 18 is embedded in the threaded insert part 14 . At one end of the thread, the bore of the threaded insert part 14 is open, while at the other end there is an additional thermoplastic material 32 forming the cap. The additional thermoplastic material 32 is the base of the molded threaded insert 20 where the base is positioned against an assembly feature site on the thermoplastic composite part. In some embodiments, the thickness of the additional thermoplastic material is in the range of 0.5-2 mm. It will be appreciated that thicknesses less than 0.5mm and greater than 2mm may be used. To enhance the bond strength of the base to the underlying thermoplastic composite part 12, the base of the molded threaded insert 20 may have fillets or chamfers with a larger diameter than the main body.

Returning to FIG. 1 , at step 22 one or more of the fabricated assembly feature parts 20 are positioned on respective assembly feature locations 26 , 28 of the thermoplastic composite part 12 . In some embodiments, a second compression tool is used to bond assembly feature part 20 to thermoplastic composite part 12 . The discrete assembly feature parts 20 are placed in the second compression tool with the formed thermoplastic composite part 12 . The second compression tool is configured for the formed thermoplastic composite part 12 to be positioned in the specific first position and aligned and has specifically positioned cavities corresponding to each assembly feature location 26 , 28 . Each cavity is configured to receive a respective one of the discrete assembly feature parts 20 . At step 24, once the second compression tool is loaded with the formed thermoplastic composite part 12 in the first location and the discrete assembly feature parts 20 are loaded in the cavities, the second compression tool is heated to a specified temperature, And compression is applied to compress each discrete feature 20 to the thermoplastic composite part 12 at each assembly feature location 26 , 28 . In connection with the exemplary molded threaded insert 20 , additional thermoplastic material 32 is bonded to the thermoplastic composite component 12 . FIG. 3 shows a cutaway side view of the molded threaded insert 20 bonded to the thermoplastic composite component 12 . As shown in FIG. 3 , the base of the molded threaded insert 20 formed of additional thermoplastic material 32 is bonded to the thermoplastic composite component 12 at an assembly feature location 34 . At each assembly feature site 26, 28, the thermoplastic material at the interface between each discrete assembly feature part 20 and the thermoplastic composite material used to form the thermoplastic composite part 12 is melted or reflowed Each discrete assembly feature part 20 is substantially "welded" to the thermoformed thermoplastic composite part 12 while cooling. One aspect of this process is managing the amount of thermoplastic material at the interface of each feature site to control welding. Another aspect of this process is precisely controlling the temperature applied to the assembly feature parts 20 and the thermoplastic composite part 12 to enable the bonding of each assembly feature part 20 to the thermoplastic composite part 12 while maintaining the thermoplastic composite part 12 integrity. To ensure the success of the bonding process, the thermoplastic layer 18 of the molded threaded insert 20 should be compatible with the thermoplastic resin matrix of the thermoplastic composite part 12 . The interface area between the molded threaded insert 20 and the compound also determines the bonding force. In an exemplary application, using nine-ply carbon fiber thermoplastic prepreg, the thermoplastic resin matrix of the thermoplastic composite is polycarbonate, and the thermoplastic used to overmold the threaded insert part 14 is also polycarbonate. The threaded insert part 14 of the molded threaded insert 20 measures ISO M4 x 0.7 with an outer diameter of 6 mm and the overmolded thermoplastic layer 18 surrounding the threaded insert part 14 is 10 mm in diameter. Test bond forces between such molded threaded inserts 20 and thermoplastic composite parts were above 1000 Newtons.

The present application has been described in terms of specific embodiments incorporating details to facilitate the understanding of principles of construction and operation of thermoplastic composite component assemblies and methods of manufacture. Many of the components shown and described in the various figures may be interchanged to achieve the necessary results, and this description should also be understood to cover such interchanges. Therefore, references herein to specific embodiments and details thereof are not intended to limit the scope of the appended claims. It will be apparent to those skilled in the art that modifications may be made to the selected embodiments for illustration without departing from the spirit and scope of the application.

related application

This patent application claims priority under 35 U.S.C.119(e) to co-pending U.S. Provisional Patent Application No. 62/732,690, filed September 18, 2018, entitled "ASSEMBLY OFSUB-COMPONENTS BY COMPRESSION MOLDING," Its entire content is incorporated herein by reference.

Claims (18)

1. A method of making a thermoplastic composite part assembly, the method comprising: a. manufacturing discrete assembly feature parts, wherein the assembly feature parts include one of studs, fasteners, or threaded inserts; b. manufacturing a discrete thermoplastic composite part having an outer surface that is the outer surface of a complete thermoplastic composite part assembly formed by performing a compression molding process on the thermoplastic composite material; c. aligning the assembly feature part with an assembly feature site on the outer surface of the thermoplastic composite part, and positioning the assembly feature part in contact with the outer surface of the thermoplastic composite part at the assembly feature site; and d. Applying heat and compression to bond the assembly feature part to the outer surface of the thermoplastic composite part at the assembly feature location to form a complete thermoplastic composite part assembly, the assembly feature part attached to the complete thermoplastic At and extending outward from the exterior surface of a composite part assembly. 2. The method of claim 1, wherein aligning the assembly feature part with the assembly feature location on the outer surface of the thermoplastic composite part comprises loading the formed thermoplastic composite part into a compression tool, the The compression tool includes a first location in which the formed thermoplastic composite part is positioned, and a cavity in which the assembly feature components are positioned: and applying heat and compression using the compression tool to allow the assembly feature The thermoplastic layer is reflowed at the distal end of the part that is bonded to the thermoplastic composite part at the assembly feature location. 3. The method of claim 1, wherein the compression molding process includes applying heat and compression to the thermoplastic composite material. 4. The method of claim 3, wherein the thermoplastic composite part has a molded shape. 5. The method of claim 1 , wherein the thermoplastic composite part comprises a plurality of thermoplastic composite layers, and manufacturing the thermoplastic composite part further comprises performing a pre-consolidation process to form a non-molded laminated thermoplastic composite layer, and Performing the compression molding process includes performing a first compression molding process on the laminated thermoplastic composite layers to form the thermoplastic composite part, wherein the assembly feature parts are then aligned and positioned on the formed thermoplastic composite part and used a second A compression molding process is incorporated into the formed thermoplastic composite part, the second compression molding process being separate from the first compression molding process. 6. The method of claim 5, wherein each thermoplastic composite layer comprises a thermoplastic material and a fiber reinforcement. 7. The method of claim 1, wherein applying heat and compression includes applying a compression molding process. 8. The method of claim 7, wherein the assembly feature part includes a thermoplastic layer located at a distal end, and aligning the assembly feature part with the assembly feature site on the thermoplastic composite part comprises placing the assembly feature at the The thermoplastic layer at the distal end of the assembly feature part is placed against the thermoplastic composite part, and the compression molding process is applied to melt the thermoplastic layer to the assembly feature part at the assembly feature site The distal end is bonded to the thermoplastic composite component. 9. The method of claim 1, wherein the assembly feature includes a threaded insert, and the threaded insert includes a threaded insert and a thermoplastic layer coupled to the threaded insert. 10. The method of claim 9, wherein the threaded insert has a threaded hole exposed at a first end of the threaded insert, and the thermoplastic layer is formed over the threaded insert. A cover is formed over the second end of the 11. The method of claim 10, wherein the cap of the threaded insert is positioned against the thermoplastic composite part, and heat and pressure are applied to melt the cap to bond with the thermoplastic at the assembly feature location. Composite parts combined. 12. The method of claim 1, further comprising manufacturing a plurality of the discrete assembly feature parts, aligning each of the plurality of assembly feature parts with a corresponding assembly feature location on the thermoplastic composite part, And applying heat and compression to bond each of the plurality of assembly feature parts to the thermoplastic composite part at each of the respective assembly feature locations. 13. The method of claim 12, wherein applying heat and compression comprises applying a compression molding process to simultaneously bond each of the plurality of assembly feature parts at each of the respective assembly feature locations onto the thermoplastic composite part. 14. The method of claim 13, wherein aligning each of the plurality of assembly feature parts with a corresponding assembly feature location on the thermoplastic composite part comprises placing each of the plurality of assembly feature parts One is positioned in a corresponding cavity within the compression molding tool and the thermoplastic composite part is positioned in the compression molding tool in a holding position. 15. A thermoplastic composite part assembly comprising: a. a thermoplastic composite part having an exterior surface that is the exterior surface of a complete thermoplastic composite part assembly, wherein the thermoplastic composite part includes assembly feature locations on said exterior surface; b. An assembly feature part that is compression molded onto the thermoplastic composite part, wherein the assembly feature part includes one of a stud, a fastener, or a threaded insert, and wherein the assembly feature part locates To make contact with the outer surface of the thermoplastic composite part at the location of the assembly feature to which the assembly feature part is compression molded to form a complete thermoplastic composite part assembly, the assembly feature part is attached to the complete thermoplastic composite part. At and extending outward from the exterior surface of a composite part assembly. 16. The thermoplastic composite part assembly of claim 15, wherein the thermoplastic composite part has a molded shape. 17. The thermoplastic composite part assembly of claim 15, wherein the thermoplastic composite part comprises a plurality of thermoplastic composite layers laminated together. 18. The thermoplastic composite component assembly of claim 15 , wherein the assembly feature part includes a thermoplastic layer at a distal end, and the thermoplastic layer at the distal end of the assembly feature part is at the assembly feature bonded to the thermoplastic composite part at the component site.

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