Blade Machining with Integrated Semi-Finishing and Finishing Toolpaths

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Solution Overview

Problem

Traditional machining processes for blades and aerofoils in turbine engines are inefficient due to high manufacturing costs, tool wear, and material distortion, leading to inaccuracies and poor surface finish, particularly when machining thin sections.

Innovation Solution

Combining semi-finishing and finishing processes using a single CNC program that alternates between semi-finishing and finishing toolpaths, maintaining a self-supporting thickness of material and employing variable spindle speed and feed rate controls to optimize tool life and surface finish.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional separate process steps (roughing, semi-finishing, finishing) are used, then manufacturing completeness is achieved, but machining time and tool wear increase

Engineering Contradiction:

Improveblade shape accuracyVSAvoidmachining time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent combines semi-finishing and finishing operations into a single integrated process step. The method performs both semi-finishing and finishing of blade sections in one continuous operation without requiring separate process steps, thereby reducing total machining time while maintaining manufacturing precision through controlled material removal and support structure maintenance

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent maintains continuous useful action by keeping the support structure in place throughout the machining process. The support structure is only removed after all machining operations are complete, allowing uninterrupted semi-finishing and finishing operations. This continuity eliminates the need to reposition or re-support the workpiece between operations, reducing machining time while maintaining precision

Inventive Principle:

Principle #20Continuity of useful action

2Manufacturing precision

If material is sequentially removed in separate processing steps, then blade shaping is achieved, but material strength decreases and distortion increases

Engineering Contradiction:

Improveblade shape accuracyVSAvoidpart strength during machining

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent creates a support structure before machining begins that extends beyond the blade trailing edge. This preliminary support structure prevents distortion and maintains strength during the entire machining process. The support structure is positioned to counteract cutting forces and prevent blade section distortion before machining operations commence

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The support structure acts as a cushioning element that absorbs and distributes cutting forces during machining. By providing this protective support before and during the machining process, the blade sections are protected from distortion and excessive stress that would occur if material were removed without support

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If terraced support structure is created by traditional CNC milling, then additional strength is provided, but non-uniform shape causes tool damage and excess material

Engineering Contradiction:

Improvepart strength during machiningVSAvoidtool wear and damage

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent creates a support structure with uniform cross-sectional geometry rather than the traditional terraced shape. This uniform local quality throughout the support structure provides consistent strength while presenting a uniform geometry to the cutting tool, eliminating the uneven cutting conditions that cause tool damage and excessive wear associated with terraced shapes

Inventive Principle:

Principle #3Local quality

4Device complexity

If multiple component sections are processed separately, then complexity is reduced, but number of processing sections increases

Engineering Contradiction:

Improveprocess complexityVSAvoidnumber of processing sections

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent merges multiple blade sections into a single support structure that spans across all sections. This unified approach allows all blade sections to be processed simultaneously in one machining operation rather than requiring separate processing of each section, thereby reducing the number of processing steps while managing complexity through the unified support structure

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP3356896B1System and method for machining blades, blisks and aerofoils

Publication Date: 2020.10.28 DELCAM

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AI summary

Systems and method relating to machining parts include a CNC system including CNC machining tools, and a computer including a processor and a computer-readable medium, wherein the computer-readable medium encodes instructions of a single NC program that, when run on the processor, causes the computer to control a selected CNC machining tool to perform operations including alternating between (i) moving the selected CNC machining tool along a semi-finishing toolpath segment using a first set of spindle speed and feed rate values to remove a next portion of rough stock material in a next region of a part being manufactured, and (ii) moving the selected CNC machining tool along a finishing toolpath segment to remove a semi-finishing thickness portion of the part in the next region, wherein the first set of spindle speed and feed rate values are different from the second set of spindle speed and feed rate values.