Multiple Stud Tensioner with Gravity Sensor Positioning

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for tensioning rod-like members, such as threaded studs, face challenges in precisely controlling axial force, introducing torsion residual stresses, and requiring cumbersome manual installation and monitoring of elongation sensors, particularly in large mechanical assemblies like nuclear reactor shells.

Innovation Solution

A multiple stud tensioner machine with a sensor supporting assembly that automatically positions wireless elongation sensors using gravity and mechanical guides, eliminating the need for manual installation and enabling simultaneous monitoring through wireless communication with a computer system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual installation and monitoring of elongation sensors is used, then sensor monitoring capability is achieved, but installation and disassembly time increases significantly

Engineering Contradiction:
Improveelongation monitoring capabilityVSAvoidsensor installation and disassembly time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The sensor system is segmented into modular units, each with its own supporting assembly that can be independently positioned and installed on individual studs. This allows parallel installation of multiple sensors rather than sequential manual mounting, significantly reducing total installation time while maintaining monitoring precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sensor supporting assembly incorporates automatic positioning mechanisms that enable the sensor to be self-positioned on the stud without requiring manual alignment or complex mounting procedures. The assembly itself provides the means for its own installation, reducing labor time and complexity.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If multiple individual sensors are manually mounted on each stud, then elongation measurement of each stud is enabled, but operational complexity increases

Engineering Contradiction:
Improveindividual stud elongation measurementVSAvoidsensor installation and management complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor supporting assembly is designed as a universal platform that can accommodate and position multiple sensor types on different studs using the same basic mechanism. This multi-functional design reduces the variety of specialized components needed, simplifying the overall system despite the need to monitor multiple individual studs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sensor supporting assembly acts as an intermediary between the measurement system and the studs, providing a standardized interface that simplifies the connection and positioning process. This intermediary structure manages the complexity by absorbing the intricacies of individual sensor-stud interfaces through a统一的支撑机制.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If traditional tightening method with nut is used, then securing of mechanical parts is achieved, but axial force control precision deteriorates due to friction

Engineering Contradiction:
Improvemechanical part securingVSAvoidaxial force control precision
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional nut-based mechanical tightening system with a direct axial tensioning method using actuators that apply force along the stud axis. This substitution eliminates the friction-based torque-to-force conversion problem, enabling precise axial force control while still achieving secure mechanical part attachment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts the friction problem from the tightening process by removing the nut and thread interface that causes friction losses. By applying axial force directly through actuators on the stud itself, the harmful friction effect is completely eliminated, leaving only the beneficial axial tensioning function.

Inventive Principle:
Principle #2Taking out (Extraction)

4Strength

If traditional tightening method is used, then mechanical parts can be secured, but risk of thread damage increases

Engineering Contradiction:
Improvemechanical part securingVSAvoidthread damage risk
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent replaces the high-stress thread engagement process with direct axial tensioning. By applying force along the stud axis before nut installation, the system avoids the excessive localized stresses and misalignment forces that occur during traditional thread tightening, thereby reducing thread damage risk while maintaining securing reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Simplifies the assembly and disassembly of elongation sensors, ensures quicker and safer monitoring of stud tensioning, and maintains consistent tension across multiple studs, reducing the risk of damage and improving operational efficiency.

Implementation Method 1

sensor supporting assembly adapted to receive a plurality of elongation sensors (11) arranged in a row and positioning means adapted to move one of said sensors (11) from said row into an operating engagement with one of said studs (2)

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP2553387B1Multiple stud tensioning machine and method for automatically controlling the elongation of a plurality of studs.
Publication Date: 2016.03.23 AB SKF SKF PATENT DEPARTMENT
  • EP2553387B1 patent drawingFigure 1
  • EP2553387B1 patent drawingFigure 2
  • EP2553387B1 patent drawingFigure 3

AI summary

A multiple stud tensioner machine adapted to exert a longitudinal pre-stressing traction on a plurality of studs (2), the stud tensioner machine comprising a sensor supporting assembly (6) adapted to receive a plurality of elongation sensors (11) arranged in a row and positioning means adapted to move one (11a) of said sensors from said row into an operating engagement with one (2a) of said studs.