Ribbed Insert Nut Retainer for Resin Flow and Pull-Out Strength
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Solution Overview
Problem
Insert nuts with fine spiral grooves face poor moldability and durability issues when embedded in resin bases, particularly with carbon fiber reinforced resins, due to difficulty in resin flow and susceptibility to cracks or breakage.
Innovation Solution
A retainer design featuring longitudinal and transverse ribs on its outer surface, connected to each other, which secures rotational torque and pull-out load without hindering resin flow, enhancing mechanical strength and moldability.
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 the pull-out load and rotational torque are improved, but the moldability deteriorates due to difficulty in resin flow
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 bonding surfaces are localized to specific annular band portions rather than covering the entire shaft portion. This local quality approach concentrates the bonding function in specific regions while leaving other regions open for resin flow, thereby improving both bonding force and moldability.
2Strength
If multiple fine spiral grooves are formed on the annular band portion to enhance bonding force, then the pull-out load and rotational torque are improved, but the durability deteriorates due to crack or breakage occurrence
Solution Approach 1:
The spiral groove structure is segmented into discrete annular bands with gaps, eliminating the continuous sharp edges that cause stress concentration. This segmentation prevents crack propagation and improves durability while maintaining bonding effectiveness.
Solution Approach 2:
The gaps between annular bands, which might be seen as reducing bonding area, actually serve to prevent crack propagation and improve durability. The structure converts the potential harm of continuous grooves into the benefit of crack arrest zones, thereby improving reliability.
3Strength
If carbon fiber reinforced resin is used to enhance strength, then the pull-out load and rotational torque are improved, but the moldability deteriorates due to poorer resin flow
Solution Approach 1:
The segmented annular band structure creates natural flow channels for carbon fiber reinforced resin, allowing the viscous material to flow more easily during molding while still providing sufficient bonding surfaces. This resolves the contradiction between using strong carbon fiber resin and maintaining moldability.
Data Source
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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.