Plastic Rod and Metal Nut Fastening Assembly
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Solution Overview
Problem
Existing fastening assemblies for motor vehicle equipment parts are costly and complex to implement, lacking a simple and cost-effective solution for securely fixing two pieces of equipment.
Innovation Solution
A fixing assembly comprising a plastic rod and a metallic nut with a unique internal thread design, featuring flanks forming an angle of 25° to 35°, a V-shaped thread bottom, and a truncated crest, allowing for easy screwing and high tightening torque without material removal, facilitating easy assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fastening assemblies are used, then secure fixing of motor vehicle parts is achieved, but the implementation cost and complexity increase
Solution Approach 1:
The fastening assembly is divided into two distinct components: a plastic rod integrated with the first part and a separate metallic nut with internal threading. This segmentation allows each component to be optimized independently - the rod provides structural integration while the nut provides adjustable fastening capability, simplifying manufacturing and assembly processes
Solution Approach 2:
The plastic rod acts as an intermediary element between the two motor vehicle parts. Instead of directly fastening the parts together, the rod serves as a mediator that receives the metallic nut, which then applies the fastening force. This intermediary approach distributes stresses more effectively and simplifies the fastening mechanism
2Reliability
If conventional threading is used, then fastening is achieved, but high screwing torque is required and material removal may occur
Solution Approach 1:
The conventional 60° thread angle is changed to a shallower angle between 25° and 35°. This parameter change in the thread geometry reduces the friction and engagement resistance during screwing, thereby lowering the required screwing torque. The modified thread profile also prevents material removal or damage to the plastic rod during the fastening process
Solution Approach 2:
The thread flanks are designed with asymmetric properties - the angle distribution and surface characteristics are optimized locally to reduce friction during insertion while maintaining sufficient gripping force for secure fastening. The local geometry is tailored to match the material properties of the plastic rod
3Reliability
If traditional fastening systems are used, then parts are secured, but disassembly and recycling become difficult
Solution Approach 1:
The fastening system transitions from a permanent or difficult-to-remove connection to a dynamic, reversible connection. The metallic nut can be easily unscrewed and removed from the plastic rod, allowing for simple disassembly. This dynamic capability enables both parts to be separated and recycled independently without special tools or complex procedures
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 assembly provides a simple, cost-effective solution for securely fixing motor vehicle parts with reduced screwing torque during assembly and easy unscrewing for recycling, ensuring satisfactory retention and easy disassembly, suitable for both small series and mass production.
Implementation Method 1
a nut (10) intended to be screwed onto the rod (8) by forming an external thread in the rod (8) during first screwing
Data Source
Figure 1~2
Figure 3~4
AI summary
The assembly of the invention includes a rod (8) made of a plastic material and a metal nut (10) to be screwed onto the rod (8) by forming an outer threading on the rod (8) upon the first screwing operation, the nut (10) having an inner threading that comprises at least one thread (32), the or each thread (32) comprising two flanges (36) defining between them an angle of between 25° and 35°.