Composite Wood-Vinyl Door Frame Resists Decay
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Solution Overview
Problem
Traditional wood frame door assemblies are prone to decay and structural compromise due to moisture exposure, and alternative materials like aluminum or vinyl are either expensive or lack rigidity and impact resistance.
Innovation Solution
A door assembly featuring a composite frame member with a core made of non-metallic wood and a two-piece top piece composed of a cellulosic-plastic composite, where the cellulosic portion is wood fiber and the plastic portion is thermoplastic, providing decay resistance and structural stability while maintaining the appearance of traditional wood frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional wood frame materials are used, then aesthetic appeal and structural strength are improved, but decay resistance and moisture resistance deteriorate
Solution Approach 1:
The frame member uses a composite construction with a wood core providing structural strength and a decay-resistant outer layer (vinyl, aluminum, or other non-wood material) providing protection against moisture and decay. This composite approach allows the frame to simultaneously achieve the aesthetic appeal and strength of wood while gaining decay resistance.
Solution Approach 2:
Different portions of the frame member have different material properties - the core maintains wood characteristics for strength and aesthetics, while the outer layer or lower portion uses decay-resistant materials specifically where moisture exposure is greatest, creating localized protection where needed most.
2Reliability
If aluminum cladded wood frames are used, then decay resistance is improved, but cost increases
Solution Approach 1:
Instead of fully cladding the entire frame in expensive aluminum, the invention applies decay-resistant material only to specific areas - primarily the lower portion or outer layer - while maintaining wood core in other areas, thereby reducing material costs while still achieving adequate decay resistance.
Solution Approach 2:
The invention uses more cost-effective decay-resistant materials (such as vinyl or treated wood) rather than expensive aluminum cladding, providing adequate protection at a lower cost point that makes the product more competitive.
3Ease of manufacture
If vinyl film cladded wood frames are used, then cost is reduced, but impact resistance deteriorates
Solution Approach 1:
The frame member combines a rigid wood core that provides impact resistance with a vinyl or other cost-effective outer layer that provides decay resistance. This composite structure achieves both cost reduction and maintained structural integrity, overcoming the weakness of vinyl-only constructions.
Solution Approach 2:
The rigid wood core is maintained in areas requiring impact resistance, while vinyl cladding is applied in areas where cost reduction is prioritized, creating a differentiated material distribution that optimizes both strength and cost-effectiveness.
4Reliability
If all plastic extruded frames are used, then cost is reduced and decay resistance is improved, but rigidity and heat resistance deteriorate
Solution Approach 1:
The frame member uses a rigid wood core that provides structural rigidity and dimensional stability, combined with a plastic or vinyl outer layer that provides decay resistance. This composite construction overcomes the flexibility and heat deformation issues of all-plastic frames while maintaining cost-effectiveness and moisture protection.
Solution Approach 2:
The rigid wood material is positioned in the core where structural rigidity is most needed, while the plastic coating is applied to the outer surface where decay protection is the primary function, creating a differentiated structure that optimizes each material's strengths for its specific role.
Data Source
AI summary
A door assembly. The door assembly may include at least one door panel and a door frame having a plurality of frame members including a header and a pair of side jambs. The invention may also be considered a frame member. The frame member may include a core; and a two-piece top piece adjoining the core to form a structural member. The core and the top piece may be a composite of cellulosic material and at least one other material. The door assembly may further include at least one adjacent panel. Also disclosed are door jamb frame members and mullion frame members.