Cooling Channel Piston Opening with Circular Milling Chip Control

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Solution Overview

Problem

Existing methods for producing cooling channel pistons, such as milling or drilling, result in chip formation that can enter the cavity and contaminate the oil circuit, while electrochemical drilling is environmentally harmful and inefficient for series production.

Innovation Solution

A CNC-controlled circular milling process using a special milling cutter with end cutting edges in a wave profile and a high-pressure flushing process to create through openings in the piston blank, minimizing particle entry and facilitating easy removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional milling or drilling processes are used to create through-holes in the piston blank, then the opening can be produced in the solid material, but chips are generated that can penetrate the cooling channel cavity and contaminate the oil circuit

Engineering Contradiction:
Improveease of producing openingVSAvoidchip contamination
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention changes the geometric parameters of the milling tool by using a specific point angle between 170° and 180° (preferably 174°) and arranging cutting edges in a wave profile. These parameter changes modify the chip formation and ejection characteristics, preventing chips from entering the cooling channel cavity while maintaining efficient material removal

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of trying to prevent chip formation or protect the cavity from chips, the invention inverts the approach by designing the milling tool to eject chips away from the cavity in a controlled manner. The wave-profiled cutting edges create a chip ejection path that directs chips outward, away from the cooling channel opening

Inventive Principle:
Principle #13The other way round (Inversion)

2Object-affected harmful factors

If electrochemical drilling process (ECM) is used to prevent particles from entering the cavity, then particle contamination is avoided, but the process pollutes the environment and does not achieve desired cycle times in series production

Engineering Contradiction:
Improveparticle contaminationVSAvoidcycle time
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The invention replaces the electrochemical drilling process (ECM) with a mechanical milling process that uses a specifically designed milling tool. This substitution eliminates the environmental pollution associated with ECM while achieving comparable or better productivity through optimized mechanical chip ejection

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

By changing the geometric parameters of the milling tool (point angle of 170°-180° and wave profile cutting edges), the invention achieves effective chip ejection that prevents contamination without requiring the lengthy cycle times of ECM processes

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If electrochemical drilling process (ECM) is used to prevent particles from entering the cavity, then particle contamination is avoided, but the process pollutes the environment

Engineering Contradiction:
Improveparticle contaminationVSAvoidenvironmental pollution
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The invention replaces the electrochemical drilling process (ECM) with a mechanical milling process. This substitution eliminates the chemical pollution associated with ECM while maintaining effective prevention of particle contamination through controlled chip ejection

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If a standard milling cutter is used to create the through-hole, then the opening can be produced, but a cover may form that obstructs oil flow or detaches and remains in the cavity

Engineering Contradiction:
Improveease of producing openingVSAvoidoil flow reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the point angle parameter to between 170° and 180° (preferably 174°) and arranges cutting edges in a wave profile. These parameter changes prevent the formation of a cover (cap) at the end of the through-hole by controlling the material removal pattern and chip ejection, ensuring smooth oil flow into the cooling channel

Inventive Principle:
Principle #35Parameter changes

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

Prevents particle contamination, reduces cycle time, and lowers production costs by using a more affordable and maintainable tooling compared to electrochemical drilling, while ensuring efficient oil flow in cooling channels.

Implementation Method 1

the opening is introduced into the blank by a CNC-controlled circular milling process

Methodology Applied
Scientific EffectCNC control:

Implementation Method 2

a circular milling process with a circular feed motion of the tool around its longitudinal axis

Methodology Applied
Scientific EffectCircular milling:

Implementation Method 3

the cooling channel is subjected to a high-pressure flushing process

Methodology Applied
Scientific EffectHigh-pressure flushing: Fluid Spray

Data Source

PatentEP3468735B1Cooling channel opening by means of circular milling operation
Publication Date: 2024.05.15 KS LARGE BORE PISTONS GERMANY GMBH
  • EP3468735B1 patent drawingFigure 1
  • EP3468735B1 patent drawingFigure 2

AI summary

The invention relates to a method for producing a cooling channel piston, wherein a blank of the cooling channel piston, which has a cavity designed as a cooling channel, is provided and wherein an inlet or outlet opening is introduced into the blank in the direction of the cooling channel, characterized in that the opening is introduced into the blank by means of a CNC-controlled circular milling process by using a special milling cutter having end cutting edges arranged in a shaft profile.