Multi-Piece Bolt Assembly for High-Torque Preload Joints

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Standard bolts often fail under high torque and preload conditions due to concentration of forces at the weakest point where the bolt shaft meets the bolt head.

Innovation Solution

A multi-piece bolt design featuring a threaded shaft with a flared protrusion and a bolt head with a deformable body and relief space, allowing for higher preload and torque application without shearing or popping off the bolt head.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a standard bolt design is used, then the structure is simple and easy to manufacture, but the bolt fails under high torque and preload due to force concentration at the shaft-head junction

Engineering Contradiction:

Improvetorque and preload capacityVSAvoidbolt structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The bolt is divided into multiple pieces: a shaft portion and a head portion that are separately formed and then assembled together through threading. This segmentation allows each component to be optimized independently and distributed the stress concentration problem to the threaded connection, preventing failure at the shaft-head junction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shaft is inserted into the head through a threaded connection where the external threads of the shaft engage with the internal threads of the head. This nested arrangement creates a strong mechanical bond that distributes forces along the threaded interface rather than concentrating them at a single point.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Force

If preload force is increased to secure the joint, then the clamping force improves, but the bolt shaft may shear or the bolt head may pop off at the connection point

Engineering Contradiction:

Improvepreload forceVSAvoidbolt failure resistance

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

By separating the shaft and head into distinct components connected by threads, the preload force is distributed along the entire threaded engagement length rather than being concentrated at the shaft-head junction, preventing shear failure and head popping.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The force distribution is extended from a point connection (shaft-head junction) to a distributed connection along the threaded interface, adding a dimensional aspect to force distribution that prevents localized failure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12241494B2Multi-piece bolts and methods of making the same

Publication Date: 2025.03.04 CRUSHLOCK INC

AI summary

A bolt includes a threaded shaft and a bolt head. The threaded shaft has a first end, a second opposing end, and an external thread. The first end includes a flared protrusion and the external thread is wrapped about the shaft and extends from the second opposing end to the flared protrusion. The bolt head includes an interior threaded bore for threadingly engaging the external thread of the threaded shaft, a front surface, and an opposing back surface having a recess configured to receive at least a portion of the flared protrusion of the threaded shaft therein.