Pre-Firing Ceramic Core Deburring with Helical Milling
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Solution Overview
Problem
Manual deburring of ceramic cores for turbine engine blades is challenging due to complex geometry, high precision requirements, and the risk of musculoskeletal disorders, with automated post-firing deburring hindered by dimensional variations from shrinkage.
Innovation Solution
Deburring is performed before firing using a helical milling tool with a hemispherical end, cooled by air, and optimized cutting parameters to prevent jamming and ensure repeatable, high-quality removal of burrs, facilitated by a device with a rotating tool holder and coolant nozzle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual deburring is performed after firing, then deburring can be done on the final product, but the operation becomes increasingly difficult to achieve with precision and repeatability due to complex core geometry and shrinkage deformation
Solution Approach 1:
The patent applies preliminary action by performing deburring on the green state core before firing. This eliminates the complexity of deburring after firing when shrinkage deformation occurs, allowing precise and repeatable removal of burrs from complex geometries such as HP high-pressure stage moving blades and HP fixed distributors without the operational difficulties associated with post-firing deburring.
2Productivity
If automated deburring is performed after firing, then productivity increases, but the dimensional variations from shrinkage make the process tricky and difficult to automate
Solution Approach 1:
The patent performs deburring in the green state before firing, when the core has not yet undergone shrinkage deformation. This timing allows automated deburring systems to operate on consistent dimensional geometries, eliminating the automation difficulties caused by post-firing dimensional variations while maintaining high productivity through series production capability.
Solution Approach 2:
The patent changes the temporal parameter of the deburring operation from post-firing to pre-firing (green state). This parameter change transforms the deburring process from one affected by shrinkage deformation to one operating on stable green state dimensions, enabling successful automation while maintaining precision.
3Manufacturing precision
If manual deburring is performed repeatedly on complex cores, then burrs can be removed, but operators develop musculoskeletal disorders (MSDs) that are harmful to their health
Solution Approach 1:
The patent replaces manual mechanical deburring operations with an automated deburring system. This substitution eliminates repeated manual handling of fine and complex cores, preventing operators from developing musculoskeletal disorders while maintaining the ability to perform precise burr removal on complex geometries such as HP high-pressure stage moving blades.
4Extent of automation
If automated deburring is attempted after firing, then repeatability improves, but the deformation from shrinkage makes the process poorly controllable
Solution Approach 1:
The patent performs deburring in the green state before firing, when dimensional stability is maintained. This timing allows automated systems to operate with full controllability on consistent geometries, eliminating the poor process controllability caused by shrinkage deformation that plagues post-firing automated deburring attempts.
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
This method reduces crack onset, improves deburring quality, and decreases manufacturing cycles and costs by enabling automated, precise burr removal without post-firing deformation issues.
Implementation Method 1
a milling tool with a helix with an angle of between 20 and 70° and with a hemispherical end is used. In this way, the cut material is drawn in and moved away from the cutting zone, reducing the risk of jamming.
Implementation Method 2
the cooling is ensured by diffusion of a fluid in the direction of the surface portion to be deburred. This is, for example, air.
Data Source
Figure 1~5
AI summary
The present invention relates to a method for deburring a ceramic foundry core (10) obtained by injecting a ceramic paste, said paste including a binder having a predetermined glass transition temperature, into a mold and having at least one surface portion with a surplus of material forming a burr (B) to be eliminated. The method is characterized in that it includes the following stages: a) disposing and attaching the molded, unfired foundry core (10) onto a mounting (300); b) placing a milling tool (100), having an elongated shape with a helically cut edge, onto a tool holder; c) causing the tool to rotate around its axis and touching the milling tool to said surface portion to be deburred; and d) freezing (400) the surface portion to be deburred such that the foundry core is maintained at a temperature lower than said glass transition temperature during the deburring operation.