The present disclosure relates generally to components having a high strength-to-weight ratio and processes for making the same. The disclosure finds particular application in connection with plastic components.
The disclosure is applicable to a wide range of applications in different industries, especially applications which currently use light metal alloys and carbon fiber composites. Composite materials and light alloys metals are used in a variety of applications. High stiffness to weight ratio is one of the most attractive properties of these materials/composites. This high ratio leads to lighter products that can handle heavier loading condition compared to conventional materials with lower ratios (like, for example, Iron).
Certain disadvantages of said materials can limit their use in industry significantly. For example, light alloy metals use rare earth metals that are expensive, generally hard to process and can require extensive protection against corrosive environments. Carbon fiber composites (CFC) and glass fiber composites (GFC) are not cheap either. Labor intensive manufacturing process, use of harsh chemicals and limited flexibility in product design/manufacturing limits their use.
Recycling is also an important factor in material selection for industry. Recycling of light alloy metals generally consumes high levels of energy. On the other hand, carbon fiber and glass fiber composites are rarely recyclable because of the chemicals used during their manufacturing process. Most of products made by GFC (glass fiber composites) and CFC (carbon fiber composites) end up in landfills after their service life expires.
To address these challenges, various approaches have been developed during recent years. Industry has selected carbon fiber composite (CFC) as an ideal candidate and has put forth a lot of effort to reduce its manufacturing cost. CFC still carries its series of disadvantages including limited flexibility in design and that is not generally recyclable, but has been considered as the most attractive solution to reduce components weight in the products. Current increase in energy cost (oil prices) is the main motive behind this approach.
The limitations of the prior art identified above have been identified by the inventor and the present disclosure sets forth components and methods for making the same that include one or more of the following features:
In accordance with one aspect, an assembly comprises a first component having a first side and a second side opposite the first side, the first side having at least one bonding structure extending therefrom and spaced from an outer perimeter of the first component, and a second component having a first side and a second side opposite the first side, the second component thermally bonded to the first component along at least one interior interface including said bonding structure, said interface fully enclosed between the first and second components. At least a portion of at least one of the first or second components is laser transparent to allow passage of laser energy through said laser transparent portion to a laser opaque portion of the interface, said laser opaque portion configured to absorb laser energy to facilitate bonding.
The at least one interface can include a plurality of bonding structures extending from at least one of the first or second components. The at least one interface can be between adjacent bonding structures extending respectively from the first and second components. The plurality of bonding structures can include one or more ribs having a shape. The shape can include at least one of a straight shape, a curved shaped, a closed shape, a honeycomb shape, a diamond shape, or a rectangular shape. At least one of the first or second components can be comprised of a material including at least one of thermoplastic polymers or fiber reinforced thermoplastic polymers. The materials can include polymers such as PA, PPA, PBT, and all of the thermoplastic plastics and thermoplastic elastomeric polymers.
In accordance with another aspect of the present disclosure, an assembly comprises a first part and a second part bonded to the first part, the assembly having an interior chamber and an exterior shell surrounding said chamber, the first part and second part being bonded together along an interface within said chamber, a portion of the exterior shell being laser transparent, and the interface being formed between a laser transparent part of the first part and a laser opaque portion of the second part.
The interface can include a plurality of bonding structures extending from at least one of the first or second components. The plurality of bonding structures can include one or more ribs having a shape. The shape can include at least one of a straight shape, a curved shaped, a closed shape, a honeycomb shape, a diamond shape, or a rectangular shape. At least one of the first or second components can be comprised of a material including at least one of thermoplastic polymers or fiber reinforced thermoplastic polymers. The materials can include polymers such as PA, PPA, PBT, and all of the thermoplastic plastics and thermoplastic elastomeric polymers.
In accordance with another aspect, a method of making an assembly having at least two components bonded together comprises the steps of placing a first component in contact with a second component to form an interface, the first component having a first side and a second side opposite the first side, the first side having at least one bonding structure extending therefrom and spaced from an outer perimeter of the first component, and securing the first component to the second component along an interface including the bonding structure, said interface fully enclosed between the first and second components. The securing includes passing a laser through a laser transparent portion of at least one of the first or second components to a laser opaque portion of at least one of the first or second components, whereby laser energy passing through the laser transparent portion and absorbed by the laser opaque portion heats the laser opaque portion to weld the first and second components together along an interface therebetween.
The method can further include forming the first component having the bonding structure, wherein the forming includes selecting at least one design parameter, and determining at least one of a dimension of the first component, or a location or a dimension of the at least one bonding structure based at least in part on the selected design parameter. Selecting the at least one design parameter can include selecting at least one of the following design parameters: environmental protection, impact protection, thermal insulation, acoustic insulation, thermal management, aerodynamic performance, weight reduction, enhanced resonance frequency, defined fracture path, low production cost, low tooling cost, recyclable, and/or short development cycle.
A composite material is made of a set of different materials having generally different mechanical properties joined together to provide optimum mechanical properties for a targeted application. One goal of such structure is to gain high stiffness to weight ratio for any given application. Different layers of materials are joined together using a carrier such as a polymer or adhesive.
In this disclosure, a composite structure includes a series of components, mainly made of super structural polymers, for example, as a main carrier. These carriers can be made/formed using conventional polymer forming techniques (injection molding, extrusion, forming, etc.) and joined together using a welding technique, such as a polymer laser welding technique. Location and distribution of the weld joints can predict the performance of the product under different loading conditions. In addition, internal structure of each part further enhances the load carrying capabilities where it is needed the most. Overall, an integrated structure with specific rib/weld/component configuration is the outcome of the process, which forms a solid material with enhanced functionality.
In one exemplary configuration, geometric shapes, such as a honeycomb structure, can be provided on one or both parts. When joined together through the welding process disclosed herein, the honeycomb structure can provide increased structural rigidity to the component, thereby increasing the weight to stiffness ratio of the product. Ribs/welds can also be removed or omitted in certain areas to provide a controlled path for fracture when a load limit is reached. In another example, straight ribs in parallel are used to increase the stiffness in certain directions while maintaining the flex in other directions. Flexibility in the design of the ribs and the weld paths provides virtually unlimited flexibility for the designer to move the material around as needed to enhance the product functionality/performance by placing the ribs/welds where desired to produce a given structural property.
One product made using this technique comprises at least two formed polymers. Some components can have more than two polymer components in addition to a series of supplementary materials/components (metal inserts, motors, harnesses, etc.) that may be supported inside or outside the component after welding takes place. Support geometry can be created inside the component for anchoring of the said supplementary components inside the unit to further enhance their functionality. As will be seen below,
With reference to
The embodiments illustrated in
Special features with specific geometry can be built/integrated into the unit. These features are part of the structure and are made of the laser weld-able polymers. One goal is to enhance the functionality of the product while minimizing its complexity. Examples are:
It will be appreciated that in one embodiment, the ribs are supported by both ends (welded to both ends, or integrated to one, welded to the other one). By integrated, it is meant that the lower part in
Each of the properties described above can be achieved, for example, by creating a closed shell structure with inter-connected ribs (or other structural features) fused together using a laser welding technique. In initial lab testing to verify the process, a laser welding machine from LIESTER was implemented having a diode laser operating with 140 watts of power. Laser welding is performed by using a series of laser transparent polymers and laser opaque materials. In a basic example, a first component made of a laser transparent material is placed into position with a second component made of a laser opaque material, pressed against each other using a clamping device. Laser energy is passed through the laser transparent polymer of the first component, tracing an interface area between the first and second components. The laser opaque material of the second component blocks the laser passage and the laser energy gets released, thereby melting the laser opaque material. As result the laser transparent material in contact with the laser opaque polymer gets melted too, fusing the first and second components together and creating a bond.
Another alternative would be to make mating surfaces (e.g., the interface) of the first and/or second components “laser opaque” and the rest of both/one of the component(s) transparent to the laser beam. As laser light passes through the transparent portion of either or both the first and second components, hits the interface of the first and second components and releases its energy, melting the area and forming the weld. Special coatings can be used on the mating surfaces to achieve different levels of weld integrity. Examples include coating the interface with a thin layer of material (a thin sheet of laser opaque material in the assembly configured to melt and bond with adjacent structure when exposed to laser energy), metal particles, fiber particles, and special adhesives. Location and distribution of the bond is dictated by design requirements to achieve optimum mechanical performance.
It is often assumed that the weld is one of the weakest points in the structure. However, considering the efficiency and ease of process in laser welding of the inside ribs/walls in addition to the perimeter of a given assembly, weld seams can be distributed to a wide area, eliminating the apparent weakness associated to the weld.
There are, however, several techniques to make the part 97 a blend of the transparent/opaque part to use it as a middle layer. In general a middle layer should be a blend of the laser transparent/opaque polymer in order to be weld-able to pre/post layers. Such a layer can be produced using different techniques such as: two shot molding, laser welding of the two parts, coating of the part with another polymer, or any other technique to make the part transparent in some areas and opaque on other sections. This will enable addition of more layers to the assembly. Final product will be a series of layers with different structural ribs all welded to each other using laser beam, usually a diode type laser which is fairly popular in welding of the polymers.
The following table sets forth various design parameters and manufacturing methods are summarized in accordance with the present disclosure.
This application claims priority to and the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/674,944, filed Jul. 24, 2012, which application is hereby incorporated by reference.
Number | Date | Country | |
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61674944 | Jul 2012 | US |