Insert Nut Retainer Rib Structure for Moldable Resin Anchoring
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Solution Overview
Problem
Insert nuts with fine spiral grooves face poor moldability and durability issues when insert-molded in resin bases, particularly with carbon fiber reinforced resins, due to resin flow hindrance and sharp tips leading to cracks or breakages.
Innovation Solution
A retainer design featuring a retainer main body with longitudinal and transverse ribs connected along its outer surface, eliminating the need for spiral grooves to enhance moldability and mechanical strength while securing rotational torque and pull-out load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple fine spiral grooves are formed on the annular band portion to enhance bonding force, then rotational torque is improved, but moldability deteriorates due to resin flow hindrance
Solution Approach 1:
The continuous spiral groove is segmented into multiple discrete annular band portions with gaps between them. This segmentation allows resin to flow through the gaps while still providing bonding surfaces, thus resolving the contradiction between enhancing bonding force and maintaining moldability.
Solution Approach 2:
The outer circumferential surface is designed with different local structures: annular band portions with spiral grooves for bonding, and gaps without grooves for resin flow. This local differentiation allows each region to serve its specific function, resolving the contradiction between bonding force and moldability.
2Strength
If multiple fine spiral grooves are formed on the annular band portion, then bonding force is enhanced, but durability deteriorates due to sharp tips causing cracks or breakage
Solution Approach 1:
By segmenting the spiral groove into discrete annular bands separated by gaps, the continuous sharp tips are eliminated. The gaps act as stress relief zones that prevent crack propagation, thus improving durability while maintaining bonding force through the grooved surfaces.
Solution Approach 2:
The gaps between annular band portions serve as pre-designed stress relief zones that cushion against crack propagation before actual failure occurs. This beforehand cushioning prevents the sharp tips from initiating catastrophic failures, thus improving durability.
3Strength
If carbon fiber reinforced resin is used for insert-molding, then strength is improved, but moldability deteriorates due to poor resin flow
Solution Approach 1:
The segmented annular band structure with gaps provides channels for carbon fiber reinforced resin to flow through during insert-molding. This segmentation reduces flow resistance and improves moldability while the grooved surfaces still provide adequate bonding for the high-strength resin.
Data Source
AI summary
To provide a retainer having excellent moldability and durability while having a predetermined pull-out load and predetermined rotational torque. The retainer includes a nut main body 10 having a female thread 11, longitudinal ribs 13 formed between a plurality of recessed portions 12 and 12 provided along an outer circumferential surface of the nut main body 10, transverse ribs 14 formed between a plurality of recessed portions 12 and 12 provided on the outer circumferential surface of the nut main body 10 along an axial center direction, and the longitudinal ribs 13 and the transverse ribs 14 are connected to each other. Then, the longitudinal ribs 13 and the transverse ribs 14 form a frame structure.