Impeller Bonding Orientation Inversion for Inner Peripheral Strength

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Solution Overview

Problem

The existing manufacturing methods for impellers in centrifugal compressors face challenges in achieving reliable bonding strength, particularly at the inner peripheral bond parts due to insufficient supply of brazing filler metal, which is exacerbated by the complex curved shapes and centrifugal forces acting on the bond parts.

Innovation Solution

The method involves forming blades integrally on a disc or cover, positioning the components to ensure the brazing filler metal flows uniformly towards the inner peripheral bond parts, and using protruding or recess portions to prevent spillage and ensure adequate material supply, thereby enhancing bonding strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the disc is positioned with the curved surface facing down during bonding, then the bonding process can be performed with the cover facing up, but the brazing filler metal flows from the inner peripheral side toward the outer peripheral side, causing insufficient supply to the inner peripheral bond part

Engineering Contradiction:

Improvebonding process accessibilityVSAvoidbonding strength at inner peripheral side

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the conventional bonding orientation by positioning the cover with its blade attachment surface facing down and the disc with its blade attachment surface facing up. This inversion reverses the flow direction of the brazing filler metal, causing it to flow from the outer peripheral side toward the inner peripheral side, thereby ensuring sufficient supply to the inner peripheral bond part that requires reliable bonding.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If brazing filler metal is disposed between the blade and disc, then bonding can be performed by heating, but the filler metal is insufficiently supplied to the inner peripheral side due to centrifugal force during rotation

Engineering Contradiction:

Improvebonding processabilityVSAvoidbonding strength at inner peripheral side

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent inverts the bonding orientation to reverse the centrifugal force effect on the brazing filler metal. By positioning the cover facing down and disc facing up, the inverted orientation causes the melted filler metal to flow toward the inner peripheral side against the centrifugal force direction, ensuring adequate supply to the high-stress inner peripheral bond region.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the orientation parameter of the bonding process, specifically inverting which component faces up or down. This parameter change fundamentally alters the flow dynamics of the brazing filler metal under centrifugal force, transforming the harmful flow direction into a beneficial one that supplies material to the critical inner peripheral region.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the passage has a complex curved shape, then aerodynamic performance is enhanced, but integral molding becomes difficult and welding requires inserting torch into narrow passages

Engineering Contradiction:

Improveaerodynamic performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the impeller into separate components (cover, disc, and blades) that can be manufactured independently. The cover and disc are formed separately, and the blades are attached through bonding processes, avoiding the need for complex integral molding of the entire impeller with its curved passages.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses brazing filler metal as an intermediary material to bond the segmented components (blades to cover and disc). This intermediary bonding approach allows assembly of complex-shaped components without requiring direct welding through narrow passages, simplifying the manufacturing process while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach ensures reliable bonding by preventing insufficient supply of brazing material to the inner peripheral bond parts, increasing the bonding strength and reliability of the bond, even under rotational stress.

Implementation Method 1

the brazing filler metal flows from the outer peripheral side toward the inner peripheral side (in an arrow direction F) along the curved surface 4d

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

bonding the plurality of blades to the blade attachment surface of the other of the disc and the cover which is not formed integrally with the plurality of blades by using a bonding material

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentEP2216119B1Manufacturing method of impeller

Publication Date: 2016.07.27 MITSUBISHI HEAVY IND LTD

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AI summary

A manufacturing method of an impeller includes: forming a plurality of blades integrally on a blade attachment surface of one of a disc and a cover; placing the cover on a floor so as to face up the blade attachment surface of the cover; disposing the disc on the cover so as to face down the blade attachment surface of the disc; and bonding the plurality of blades to the blade attachment surface of the other of the disc and the cover which is not formed integrally with the plurality of blades by using a bonding material.