Composite Deck Screw with Segmented Threads
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Solution Overview
Problem
Conventional deck screws are less effective in driving into very dense composite materials due to increased material density, leading to difficulties in securing composite and plastic materials without causing 'volcanoing' or 'mushrooming' effects.
Innovation Solution
A fastener design featuring a head with a #1 square socket configuration and an elongated shank with a left-hand thread, a right-hand thread, and an unthreaded segment, along with notches, which allows for efficient torque application and prevents material displacement during driving, reducing resistance and preventing 'volcanoing' or 'mushrooming'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deck screws are used for fastening dense composite materials, then the fastening function is compromised, but the driving difficulty increases significantly
Solution Approach 1:
The shank is divided into multiple threaded portions (first and second threaded portions with different hand directions) and an unthreaded portion, segmenting the fastening action to handle different material density zones separately, reducing overall driving difficulty while maintaining fastening reliability
Solution Approach 2:
The screw design incorporates dynamic characteristics through the interaction of left-hand and right-hand threads that create alternating engagement and disengagement patterns during driving, allowing the fastener to adapt to varying material resistance and reduce driving difficulty
2Reliability
If conventional deck screws are used for fastening dense composite materials, then the fastening function is compromised, but intense torque resistance occurs
Solution Approach 1:
The threaded shank is segmented into multiple portions with alternating hand directions, distributing the torque load across different sections and reducing peak torque resistance during the fastening process
Solution Approach 2:
The alternating left-hand and right-hand threads create a periodic engagement pattern that cycles through different torque states, allowing material displacement and reduction of intense torque resistance during driving
3Reliability
If conventional deck screws are used for fastening dense composite materials, then the fastening function is compromised, but material displacement occurs
Solution Approach 1:
The threaded portions are segmented with alternating hand directions, controlling material displacement in different zones separately and preventing the volcanoing or mushrooming effect by managing material flow through each segment
Solution Approach 2:
The use of left-hand thread instead of conventional right-hand thread in the first portion inverts the typical threading direction, creating opposite rotational effects that counteract material displacement and prevent harmful surface deformation
Data Source
AI summary
A screw for composite or plastic material comprises a head having a socket which is rotatably couplable for application of a torque. An elongated shank extends from the head and terminates a tapered threaded distal tip. The shank has one portion having an enlarged diameter and a second portion having a reduced diameter. The first portion is traversed by a left hand thread having a first pitch. The second portion is traversed by a right hand thread having a second pitch which is less than the first pitch. An unthreaded land portion adjacent the tip extends at least twice the second pitch. For some embodiments, some thread segments have notches. The fastener is particularly adapted for very dense material.