Valve Housing Welding Cap Prevents Cavity Deformation

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Solution Overview

Problem

Metal injection moulding (MIM) processes face challenges in welding valve housings due to thin walls deforming during the process, which can damage the inner cavity and hinder the free movement of internal parts, and traditional methods are costly and wasteful when manufacturing in steel.

Innovation Solution

The method involves using a welding cap for the valve housing manufactured by MIM, with a groove separating the inner liner and welding cap to prevent deformation, allowing for efficient welding without damaging the inner cavity, and utilizing a guiding ring for precise alignment, while maintaining uniform thickness for effective debinding and sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If metal injection moulding is used to manufacture the valve housing, then material usage is minimized and manufacturing cost is reduced, but the thin walls deform during welding

Engineering Contradiction:
Improvematerial wasteVSAvoidwall deformation
Core Design Contradiction:
Loss of substanceVSManufacturing precision

Solution Approach 1:

The housing is divided into two separate parts: the inner cavity portion and the welding cap. The welding cap is a separate component that is welded to the housing, isolating the welding process from the thin-walled inner cavity. This segmentation allows the thin walls to maintain their precision while still enabling welding through the separate cap component.

Inventive Principle:
Principle #1Segmentation

2Productivity

If the walls are made thin to allow debinding and sintering, then the polymeric binder can be removed effectively, but the housing deforms during welding

Engineering Contradiction:
Improvedebinding efficiencyVSAvoidwelding resistance
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The welding cap acts as an intermediary component between the welding process and the thin-walled housing. It absorbs the welding heat and mechanical stresses, protecting the thin walls from deformation while still enabling the welding process to proceed effectively.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If traditional forging or turning methods are used, then the housing has sufficient wall thickness for welding, but material waste increases and manufacturing cost rises

Engineering Contradiction:
Improvewelding capabilityVSAvoidmaterial waste
Core Design Contradiction:
StrengthVSLoss of substance

Solution Approach 1:

The housing combines MIM-manufactured thin-walled sections (for material efficiency) with a separately welded welding cap (for welding capability). This composite approach allows the thin-walled MIM parts to retain their material efficiency while the added cap provides the necessary welding interface without requiring thick walls throughout the entire housing.

Inventive Principle:
Principle #40Composite materials

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 enables cost-effective, minimal material usage in manufacturing steel valve housings with reduced deformation risks, ensuring the inner parts move freely and maintaining the integrity of the inner cavity, thus overcoming the limitations of traditional methods.

Implementation Method 1

The MIM material is heated and then injected in a mould

Methodology Applied
Scientific EffectInjection moulding:

Implementation Method 2

The part then goes through a debinding process where about 90% of the polymeric binder is removed

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 3

Then the part is sintered to remove the majority of the remaining polymeric binder and the sintering also makes the metal powder to fuse together creating a solid part

Methodology Applied
Scientific EffectSintering: Sintering

Implementation Method 4

the upper part is welded to the welding cap

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP2464905B1Manufacturing method of a valve
Publication Date: 2013.08.21 DANFOSS AS
  • EP2464905B1 patent drawingFigure 1
  • EP2464905B1 patent drawingFigure 2~3

AI summary

A method to manufacture a valve using metal injection moulding is disclosed. The valve housing (2) comprises a welding cap (14) for welding the upper part (5) of the valve to the valve housing (2). The welding cap (14) is placed so the upper part (5) can be welded to the housing (2) without damaging the inner cavity (10) of the housing. There is a gap between the welding cap (14) and the inner liner (15) so the heat from the welding do not damage the inner liner (15) allowing the inner parts of the valve to move freely.