CN110901076B

CN110901076B - Assembling of sub-components by compression molding

Info

Publication number: CN110901076B
Application number: CN201910644556.7A
Authority: CN
Inventors: 辛锐; 江维能; S.伊格诺蒂斯; 唐宇
Original assignee: Flex Ltd
Current assignee: Flex Ltd
Priority date: 2018-09-18
Filing date: 2019-07-17
Publication date: 2023-05-16
Anticipated expiration: 2039-07-17
Also published as: CN110901076A

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

Assembling of sub-components by compression molding

Technical Field

The present invention relates generally to the field of thermoplastic composites. More particularly, the present invention relates to the assembly of thermoplastic composite sub-components by a compression molding process to produce fully functional or gatepost parts.

Background

Thermoforming is a manufacturing process that heats a thermoformable material to a sufficient temperature that allows the heated thermoformable material to be molded, such as by injection molding, and cooled to a final shape. The advantage of using thermoformable materials is that they can be treated with heat.

The thermoformable composite material is a combination of a fibrous reinforcement and a resin matrix. The resin matrix may be a thermoset or thermoplastic material. Thermoplastic composites are a combination of thermoplastic materials (known as thermoplastic resins or thermoplastic resin matrices) and reinforcing materials (such as individual fibers or fabrics made from fibers). Exemplary fibrous materials include, but are not limited to, carbon, glass, aramid, polyester, jute, cellulose, and cotton. An exemplary thermoplastic composite is a Continuous Fiber Reinforced Thermoplastic (CFRT). After the material has been set, the thermoplastic material comprising the thermoplastic composite may be reshaped or reprocessed. Exemplary thermoplastic materials include, but are not limited to, polycarbonate (PC), formable PET (polyethylene terephthalate), polyamide, polyphenylene sulfide, polyether ketone, and ether ketone. Thermoset composites are combinations of thermoset materials (known as thermoset resins or thermoset resin matrices) with reinforcing materials. Thermoset materials including thermoset composites cannot be reshaped after curing, even after heating. Exemplary thermosets include, but are not limited to, polyesters and epoxies.

In many applications, it is desirable to manufacture a subassembly that is an assembly of a thermoformed composite component and an additional component. The assembly of such components may be accomplished by adhesive bonding or mechanical joints. In the case of thermoset composites, once the thermoset composite component is formed, it is difficult to further process, such as bonding to another component. 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 fiber reinforcements necessary to form such mechanical joints in thermoset composite parts. Examples of such assembly features include, but are not limited to, studs, fasteners, or threaded inserts. While it is effective to integrally form the assembly features on the thermoset composite component, thermoset materials have longer cycle times, fewer material choices, and higher costs than thermoplastic materials. Thermoplastic and thermoset composite parts are therefore becoming more popular. However, for thermoplastic materials, it is difficult to use the 3D fiber reinforcement necessary to form integral assembly features on thermoplastic composite parts. In particular, it is difficult to manufacture integral component features, such as protruding studs, using the normal compression molding process used in the manufacture of thermoplastic composite parts. In order to make mechanical engagement of the thermoplastic composite part with another part possible, threaded holes may be formed in the thermoplastic composite part, but sometimes the holes may disrupt the surface continuity of the fiber reinforcement and also create weak points in the thermoplastic composite part. To attach an assembly feature (such as a stud, fastener, or threaded insert) to a thermoplastic composite component, it is not as easy as simply drilling. Methods have been developed to attach assembly features to thermoplastic composite components.

Since the thermoplastic composite may be reprocessed, such as over-molded, after the thermoplastic composite part is formed, the assembly features may be added after the thermoplastic composite part is formed. For example, after forming the thermoplastic composite, an over-molding process may be performed to add component features. One conventional method for adding component features to a formed thermoplastic composite part is to add each new component feature individually at each new component feature location using an injection molding process. The 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 injected 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 component features to an already formed thermoplastic composite part is to place the formed thermoplastic composite part into a tool and then perform a back-side injection molding process to form any desired component features. A disadvantage of this back-molding process is that a significant amount of wasted material is required to form the assembly features, which also adds weight to the thermoplastic composite part.

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

Other conventional methods for adding component features to thermoplastic composite parts have been developed. EP0903216A2 discloses an overmolding of a steel insert with claws, which can be anchored in a thermoplastic composite part. In US 6682575 B1 a co-moulding process of a thermoplastic material with a thermoplastic interlayer material is disclosed. The molded article can be easily attached to another article (e.g., a vehicle body). In US 8197624 B2 a welding process is disclosed. This process bonds thermoplastic polymers and thermoset polymer composite components having thermoplastic surface layers together 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 composite forming a mechanical interlock to retain the insert in the thermoplastic composite. In US 9302434 B2, thermoplastic prepreg sheets are used to manufacture composite parts with molded inserts. In US 9586362 B2, a thermoplastic welding apparatus is disclosed which uses an induction coil and at least one smart susceptor. In US 9610654 B1, a method and apparatus for joining thermoplastic composite parts is disclosed, using compliant induction coils embedded in a plurality of elastomeric sheets. In US 9770892 B2, an apparatus for welding two thermoplastic composite parts together is disclosed, which uses a double sided inductor and a field absorber.

In general, conventional methods of manufacturing thermoplastic composite parts with component features first manufacture thermoplastic composite parts and then perform an over-molding process to add the component features. Although there are many different ways to attach the different features of the assembly, there are no conventional methods for directly attaching nuts or screws using compression molding.

Disclosure of Invention

Embodiments relate to a thermoplastic composite part assembly and a method of manufacturing the thermoplastic composite part assembly. The thermoplastic composite part assembly is manufactured by first performing a molding step to form individual assembly features as discrete assembly feature parts and separately forming thermoplastic composite parts using a first compression molding step. 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. This eliminates the need to add each component feature individually through a site-specific injection molding process and eliminates the wasteful material associated with a backside injection molding process.

In one aspect, a method of manufacturing a thermoplastic composite component assembly is disclosed. The method includes manufacturing a discrete component feature, manufacturing a discrete thermoplastic composite component, aligning the component feature with a component feature site on the thermoplastic composite component, and applying heat and compression to bond the component feature to the thermoplastic composite component at the component feature site 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 comprises a plurality of thermoplastic composite layers, and fabricating the thermoplastic composite part further comprises performing a pre-consolidation process to form a laminated thermoplastic composite layer, and performing the compression molding process comprises performing a compression molding process on the laminated thermoplastic composite layer to form the thermoplastic composite part. In some embodiments, each thermoplastic composite layer includes a thermoplastic material and a fibrous reinforcement. In some embodiments, applying heat and compression includes applying a compression molding process. In some embodiments, the assembly feature comprises a thermoplastic layer at a distal end, and aligning the assembly feature with the assembly feature site on the thermoplastic composite part comprises placing the thermoplastic layer at the distal end of the assembly feature against the thermoplastic composite part, and applying the compression molding process to melt the thermoplastic layer to bond the distal end of the assembly feature with the thermoplastic composite part at the assembly feature site. In some embodiments, the assembly feature component comprises one of a stud, a fastener, or a threaded insert. In some embodiments, the assembly feature comprises a threaded insert, and the threaded insert comprises a threaded insert and a thermoplastic layer coupled to the threaded insert. In some embodiments, the threaded insert has a threaded bore exposed at a first end of the threaded insert, and the thermoplastic layer forms a cap over a second end of the threaded insert. In some embodiments, the cap of the threaded insert is positioned against the thermoplastic composite component and heat and pressure are applied to melt the cap to bond with the thermoplastic composite component at the assembly feature location. In some embodiments, the method further includes manufacturing a plurality of the discrete component feature components, aligning each of the plurality of component feature components with a corresponding component feature site on the thermoplastic composite component, and applying heat and compression to bond each of the plurality of component feature components to the thermoplastic composite component at each of the corresponding component feature sites. In some embodiments, applying heat and compression includes applying a compression molding process to bond each of the plurality of component feature parts to the thermoplastic composite part at each of the respective component feature parts simultaneously. In some embodiments, aligning each of the plurality of component feature parts with a respective component feature location on the thermoplastic composite part includes positioning each of the plurality of component feature parts in a respective cavity within 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 component 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 member includes a plurality of thermoplastic composite layers laminated together. In some embodiments, the assembly feature comprises a thermoplastic layer at a distal end, and the thermoplastic layer at the distal end of the assembly feature is bonded to the thermoplastic composite component at the assembly feature location. In some embodiments, the assembly feature component comprises one of a stud, a fastener, or a threaded insert.

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 drawings include the following figures:

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

Fig. 2 shows a cut-away side view of a molded threaded insert.

FIG. 3 shows a cut-away side view of a molded threaded insert bonded to a thermoplastic composite part.

Detailed Description

Embodiments of the present application relate to a thermoplastic composite component assembly and method of manufacture. Those of ordinary skill in the art will recognize that the following detailed description of the thermoplastic composite component assembly and method of manufacture is illustrative only and is not intended to be limiting in any way. Other embodiments of thermoplastic composite component assemblies and methods of manufacture will readily suggest themselves to persons of ordinary skill 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 indicators 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 of the routine features of the implementations described herein are shown and described. It will of course be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with application-and business-related constraints, and that these specific goals may vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.

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

In the manufacturing process for manufacturing the thermoplastic composite part assembly 30, the discrete component feature parts are manufactured separately from the manufacture of the thermoplastic composite part 12. The separately manufactured component 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 a thermoplastic composite component assembly 30 according to some embodiments. The thermoplastic composite part 12 may be manufactured using one or more discrete thermoplastic composite layers 2, 4 that are combined together. Each thermoplastic composite layer 2, 4 is a combination of thermoplastic material and reinforcing material of the type previously described. In the exemplary process shown in fig. 1, N thermoplastic composite layers 2, 4 are used. In some embodiments, each thermoplastic composite layer 2, 4 is made of a fabric-thermoplastic prepreg (fibrous reinforcement in the form of a fabric) or a unidirectional thermoplastic prepreg (fibrous reinforcement made of individual fibers aligned in a single direction).

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 the pre-consolidation process, all layers 2, 4 of the composite are not pressed together completely, they simply form one loosely attached preform for ease of handling during the compression process. In some embodiments, lamination is performed using heat and pressure 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 layers 8 using a first compression molding tool at a suitable pressure and temperature to form a thermoplastic composite part 12 having a molded shape. The pressure is controlled by the molding tool and associated machinery, and the temperature is a function of the composite properties. In some embodiments, the first compression molding tool is a different tool than the tool used for lamination performed in step 6. Discrete component feature parts are manufactured separately from the thermoplastic composite part 12. In an exemplary embodiment, one or more of the component feature parts is a molded threaded insert 20. The following description is based on such molded threaded inserts 20. It should be appreciated that alternative types of assembly feature components may be manufactured and used, such as studs, fasteners, or other types of threaded inserts 20. The molded threaded insert 20 may be manufactured 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 appreciated that alternative conventional overmolding processes 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.

Fig. 2 shows a cut-away 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 thread insert part 14 is open, while at the other end there is additional thermoplastic material 32 forming the cap. The additional thermoplastic material 32 is the base of the molded threaded insert 20, wherein the base is positioned against the component features 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 should be understood that thicknesses of less than 0.5mm and greater than 2mm may be used. To enhance the bonding strength of the base to the underlying thermoplastic composite part 12, the base of the molded threaded insert 20 may have a rounded or chamfered corner with a larger diameter than the body.

Returning to FIG. 1, at step 22, one or more of the fabricated component feature parts 20 are positioned on respective component feature sites 26, 28 of the thermoplastic composite part 12. In some embodiments, a second compression tool is used to bond the assembly feature component 20 to the thermoplastic composite component 12. The discrete component feature components 20 are placed in a second compression tool along with the formed thermoplastic composite component 12. The second compression tool is configured for positioning and alignment of the formed thermoplastic composite part 12 in a particular first position and has a specially positioned cavity corresponding to each assembly feature 26, 28. Each cavity is configured to receive a respective one of the discrete component feature components 20. Once the second compression tool is loaded with the formed thermoplastic composite part 12 in the first position and the discrete component feature parts 20 are loaded in the cavity, the second compression tool is heated to a particular temperature and compression is applied to compress each discrete feature part 20 to the thermoplastic composite part 12 at each component feature site 26, 28, step 24. In connection with the exemplary molded threaded insert 20, additional thermoplastic material 32 is bonded to the thermoplastic composite part 12. Fig. 3 shows a cut-away side view of a molded threaded insert 20 bonded to a thermoplastic composite part 12. As shown in fig. 3, the base of the molded threaded insert 20 formed from the additional thermoplastic material 32 is bonded to the thermoplastic composite part 12 at assembly feature locations 34. At each of the component feature locations 26, 28, the thermoplastic material at the interface between each of the discrete component feature components 20 and the thermoplastic composite material used to form the thermoplastic composite component 12 melts or reflows, which upon cooling essentially "welds" each of the discrete component feature components 20 to the thermoformed thermoplastic composite component 12. One aspect of this process is to manage the amount of thermoplastic material at each feature site interface to control the weld. Another aspect of this process is to precisely control the temperature applied to the assembly feature 20 and the thermoplastic composite part 12 to enable each assembly feature 20 to be bonded to the thermoplastic composite part 12 while maintaining the integrity of the thermoplastic composite part 12. 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, nine layers of carbon fiber thermoplastic prepreg are used, the thermoplastic resin matrix of the thermoplastic composite is polycarbonate, and the thermoplastic used to over mold the threaded insert part 14 is also polycarbonate. The molded screw insert part 14 of the screw insert 20 has dimensions ISO M4 x 0.7, an outer diameter of 6mm, and the overmolded thermoplastic layer 18 surrounding the screw insert part 14 has a diameter of 10mm. The test bond between such molded threaded inserts 20 and thermoplastic composite parts is greater than 1000 newtons.

The present application has been described in terms of specific embodiments incorporating details to facilitate the understanding of the 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 taken to cover such exchanges. Therefore, references herein to specific embodiments and details thereof are not intended to limit the scope of the claims appended hereto. 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 APPLICATIONS

This patent application claims priority from co-pending U.S. provisional patent application No. 62/732,690 entitled "assmbly OF SUB-COMPONENTS BY COMPRESSION MOLDING" filed on date 18 at 9 OF 2018, in accordance with 35u.s.c.119 (e), the entire contents OF which are incorporated herein by reference.

Claims

1. A method of manufacturing a thermoplastic composite component assembly, the method comprising:

a. manufacturing a discrete component feature, wherein the component feature comprises one of a stud, a fastener, or a threaded insert;

b. manufacturing a discrete thermoplastic composite part having an outer surface, the outer surface being an outer surface of a complete thermoplastic composite part assembly formed by performing a compression molding process on a thermoplastic composite material;

c. aligning the assembly feature component with an assembly feature location on an outer surface of the thermoplastic composite component and positioning the assembly feature component in contact with the outer surface of the thermoplastic composite component at the assembly feature location; and

d. heat and compression are applied to bond the assembly feature component to the outer surface of the thermoplastic composite component at the assembly feature location to form a complete thermoplastic composite component assembly, the assembly feature component being attached at and extending outwardly from the outer surface of the complete thermoplastic composite component assembly.

2. The method of claim 1, wherein aligning the assembly feature component with an assembly feature location on an outer surface of the thermoplastic composite component comprises: loading the formed thermoplastic composite part into a compression tool, the compression tool comprising a first position in which the formed thermoplastic composite part is positioned and a cavity in which the assembly feature part is positioned: and applying heat and compression using a compression tool to reflow the thermoplastic layer at a distal end of the assembly feature, the distal end being bonded to the thermoplastic composite component at the assembly feature location.

3. The method of claim 1, wherein the compression molding process comprises applying heat and compression to the thermoplastic composite.

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 fabricating 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 comprises performing a first compression molding process on the laminated thermoplastic composite layer to form the thermoplastic composite part, wherein component feature parts are subsequently aligned and positioned at and bonded to the formed thermoplastic composite part using a second compression molding process that is 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 comprises applying a compression molding process.

8. The method of claim 7, wherein the assembly feature comprises a thermoplastic layer at a distal end, and aligning the assembly feature with the assembly feature location on the thermoplastic composite component comprises placing the thermoplastic layer at the distal end of the assembly feature against the thermoplastic composite component, and applying the compression molding process to melt the thermoplastic layer to bond the distal end of the assembly feature with the thermoplastic composite component at the assembly feature location.

9. The method of claim 1, wherein the assembly feature comprises a threaded insert, and the threaded insert comprises 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 bore exposed at a first end of the threaded insert and the thermoplastic layer forms a cap over a second end of the threaded insert.

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 composite part at the assembly feature location.

12. The method of claim 1, further comprising fabricating a plurality of the discrete component feature components, aligning each of the plurality of component feature components with a corresponding component feature site on the thermoplastic composite component, and applying heat and compression to bond each of the plurality of component feature components to the thermoplastic composite component at each of the corresponding component feature sites.

13. The method of claim 12, wherein applying heat and compression comprises applying a compression molding process to bond each of the plurality of component feature parts to the thermoplastic composite part at each of the respective component feature parts simultaneously.

14. The method of claim 13, wherein aligning each of the plurality of component feature parts with a respective component feature location on the thermoplastic composite part comprises positioning each of the plurality of component feature parts in a respective cavity within a compression molding tool and positioning the thermoplastic composite part in a holding position in the compression molding tool.

15. A thermoplastic composite component assembly, comprising:

a. a thermoplastic composite part having an outer surface, the outer surface being an outer surface of a complete thermoplastic composite part assembly, wherein the thermoplastic composite part comprises assembly feature locations on the outer surface;

b. a component feature compression molded onto the thermoplastic composite part, wherein the component feature comprises one of a stud, a fastener, or a threaded insert, and wherein the component feature is positioned to contact an outer surface of the thermoplastic composite part at a component feature location, wherein the component feature is compression molded to the thermoplastic composite part to form a complete thermoplastic composite part assembly, the component feature being attached at and extending outwardly from the outer surface of the complete thermoplastic composite part assembly.

16. The thermoplastic composite component assembly of claim 15, in which the thermoplastic composite component has a molded shape.

17. The thermoplastic composite component assembly of claim 15, in which the thermoplastic composite component comprises a plurality of thermoplastic composite layers laminated together.

18. The thermoplastic composite component assembly of claim 15, in which the assembly feature comprises a thermoplastic layer at a distal end, and the thermoplastic layer at the distal end of the assembly feature is bonded to the thermoplastic composite component at the assembly feature location.