Long-Shaft Inner Bore Machining Head for Precise Concentricity

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Solution Overview

Problem

Conventional long shaft inner surface machining apparatuses face challenges in machining slender long shafts with varying diameters, leading to precision issues and increased machining steps due to tool reaction forces and the need for sulfur molding, which complicates the process and reduces accuracy.

Innovation Solution

A long shaft inner surface machining apparatus that miniaturizes the machining head by supplying drive power from both ends, allowing axial and rotary movement, and uses hydraulic pressure to expand the machining head's diameter radially, ensuring precise concentricity and reducing tool reaction forces, while also simplifying the apparatus configuration and reducing the machining range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional boring bar is used for inner surface machining, then the tool can be supported by sulfur molding, but the apparatus complexity increases and machining precision deteriorates due to tool reaction forces

Engineering Contradiction:
Improvetool support stabilityVSAvoidapparatus complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the sulfur molding process from the machining system. Instead of using sulfur to support the boring bar, the patent employs a self-supported machining head that enters the prepared hole directly, removing the intermediate sulfur molding step and its associated complexity while maintaining tool stability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a machining head with a specific structure that acts as an intermediary between the external drive mechanism and the inner surface being machined. This machining head includes a blade that can be radially moved and a structure that allows it to be supported by the prepared hole itself, eliminating the need for sulfur as a mediator

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the machining head is miniaturized by supplying drive power from both ends, then the machining precision improves, but the device complexity increases

Engineering Contradiction:
Improvemachining precisionVSAvoidapparatus complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention segments the drive power supply into two independent sources: one from the external head support device and another from an internal rotary drive mechanism within the machining head. This segmentation allows the machining head to be miniaturized while maintaining precision, as each drive source handles specific functions independently

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention merges the rotary drive function directly into the machining head structure, combining what would traditionally be separate external components into a single integrated unit. This merging reduces the overall apparatus complexity while enabling the miniaturization of the machining head

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If hydraulic pressure is used to expand the machining head radially, then the concentricity improves, but the use of energy increases

Engineering Contradiction:
ImproveconcentricityVSAvoiduse of energy
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The invention employs hydraulic pressure as a controlled expansion mechanism to achieve precise radial expansion of the machining head. This hydraulic system allows for controlled, incremental expansion that maintains concentricity while minimizing energy consumption through efficient fluid pressure control

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 solution enables precise machining of long shafts with minimal deterioration in accuracy, reduces the machining range, and simplifies the process by allowing the machining head to be smaller than the prepared hole, thereby improving the machining precision and reducing the complexity of the apparatus.

Implementation Method 1

uses hydraulic pressure to expand the machining head's diameter radially, ensuring precise concentricity

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP2251124B1Long shaft inner surface processing apparatus and method of processing
Publication Date: 2023.02.22 IHI CORP
  • EP2251124B1 patent drawingFigure 1A~1D
  • EP2251124B1 patent drawingFigure 2A~2B
  • EP2251124B1 patent drawingFigure 3A~3B

AI summary

A long shaft inner surface machining apparatus of the present invention includes: a long shaft support device 10 that fixes a long shaft 1 so as not to bend; a machining head 20 capable of being inserted into the prepared hole 2 of the long shaft 1 in the axial direction; a head support device 30 that is coupled with the machining head 20 from one end of the long shaft 1 through the prepared hole 2 and moves the machining head 20 in the axial direction; and a blade drive device 40 that is coupled with the machining head from the other end of the long shaft 1 through the prepared hole 2 and rotary-drives the blade 29 around a shaft axis.