Insert Molded D-Ring Tie Down with Spring Bracket
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Solution Overview
Problem
Existing tie-down assemblies for vehicles are difficult and expensive to manufacture, particularly those with styled curved features, as they require labor-intensive cast processes and result in high waste and increased piece prices, failing to meet minimum load requirements efficiently.
Innovation Solution
An insert injection mold D-ring assembly with a metal D-ring partially encapsulated by a plastic overmold, featuring a bracket portion with an interior spring mechanism to control tension, which is cost-effective and meets the 1000-pound load requirement by using a round metal bar shaped into a D-ring and molded with a thermoplastic overmold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If cast processes are used to manufacture tie-down assemblies with curved features, then the desired shape and style are achieved, but the manufacturing cost and labor intensity increase significantly
Solution Approach 1:
The tie-down assembly is divided into two distinct components: a metal D-ring component that provides structural strength and a plastic component that provides the curved aesthetic features. These segments are manufactured separately using different processes optimized for each material's properties, then assembled together. This segmentation allows the metal part to be made cost-effectively without requiring expensive cast processes for the entire assembly.
Solution Approach 2:
The invention uses a composite structure combining metal and plastic materials. The metal D-ring provides the necessary tensile strength for load-bearing applications, while the plastic portion provides the desired curved styling and protective coverage. This composite approach allows each material to be used where it is most effective, reducing overall manufacturing cost compared to casting the entire assembly from metal.
2Shape
If oversized steel blanks are used and machined down to size, then the desired shape is achieved, but material waste and manufacturing cost increase
Solution Approach 1:
The assembly is segmented into metal and plastic components, allowing the metal D-ring to be formed from smaller, more efficient stock rather than machining down oversized blanks. The plastic component is then molded to provide the remaining shape features, eliminating the need to machine away large amounts of metal to achieve the final shape.
Solution Approach 2:
The invention changes the manufacturing parameters by switching from subtractive machining of metal to additive molding of plastic for the non-structural portions. This parameter change allows the plastic component to be formed with the exact desired shape from the start, eliminating material waste associated with machining operations.
3Strength
If traditional manufacturing processes are used, then structural strength is achieved, but the piece price and manufacturing complexity increase
Solution Approach 1:
The tie-down assembly is segmented into a metal D-ring for strength and a plastic component for styling and protection. This segmentation simplifies the manufacturing process by allowing each component to be made using its most suitable, cost-effective process, then assembled through straightforward attachment methods.
Solution Approach 2:
The composite construction combines metal and plastic materials, each providing specific functions. The metal portion handles the load-bearing requirements, while the plastic portion provides aesthetic and protective functions. This division of functional responsibilities simplifies the overall manufacturing approach compared to using a single material for all functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective and efficient method to manufacture tie-down assemblies that meet the 1000-pound load requirement, reducing waste and piece prices while ensuring strength and stability for securing cargo, with the plastic overmold enhancing the metal D-ring's structural integrity.
Implementation Method 1
An insert injection mold D-ring assembly for tie down applications, hereafter also referred to interchangeably as 'tie down device', generally comprising a D-ring with overmold
Implementation Method 2
An interior bracket located between opposing segments of the bracket portion acts as a spring to help control the tension of the bracket portion
Data Source
AI summary
A tie down device for tie down application including a D-ring with overmold used for a motor vehicle to secure cargo of various shapes and sizes using removable straps. The tie down device includes a D-ring, an overmold plastic portion, bracket portion, and an interior bracket. The tie down device withstands a minimum load requirement suitable to secure a cargo in place. A round steel bar is shaped into the D-ring feature and inserted into the mold for forming the overmold plastic portion. The plastic forms in an overmold around the metal material into the desired shape. The molding process obtains the features and shape required from at least a visual perspective and the round steel bar, which is partially encapsulated by the overmold plastic portion, provides strength to meet the predetermined load requirements. The interior bracket acts as a spring to control the tension of the bracket portion.