Laser Drilling of Injection Nozzles Using Liquid Metal Shielding

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Solution Overview

Problem

Conventional protective devices used in laser drilling of components, such as injection nozzles, suffer from wear and tear due to laser radiation, leading to reduced service life and increased reject rates in production, as they are not effectively shielded from high-power ultra-short pulses.

Innovation Solution

A method involving the use of a metallic or semi-metallic fluid with a low melting point alloy, such as a gallium-indium-tin alloy, is injected into the component's cavity to absorb and dissipate laser energy, allowing continuous flow and renewal, thereby providing permanent protection from laser radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional protective device is inserted into the cavity to block laser radiation, then the component wall is protected from laser damage, but the protective device itself suffers wear and tear from the laser radiation, limiting its service life

Engineering Contradiction:
Improveprotection reliabilityVSAvoidservice life of protective device
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention changes the physical state parameter of the protective material from solid to liquid. By using a liquid protective material instead of a solid protective device, the material can continuously flow and renew itself, preventing the wear and tear that limits the service life of solid protective devices while maintaining reliable protection against laser radiation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies hydraulic principles by using a liquid protective material that flows through the cavity. The liquid material is continuously supplied and circulated, utilizing fluid dynamics to maintain a constant protective layer against the laser beam, thereby eliminating the wear issues associated with solid protective devices

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Reliability

If a solid protective device is used to block laser radiation, then the component is protected, but the protective device requires regular replacement due to damage accumulation

Engineering Contradiction:
Improveprotection effectivenessVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention uses a liquid protective material that can be continuously supplied and circulated through the cavity, eliminating the need to stop production for replacing damaged protective devices. The continuous flow system ensures uninterrupted protection while maintaining high production efficiency

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The liquid protective material provides continuous protection without interruption. The material is continuously supplied and renewed, ensuring that the protective function is maintained without the need for periodic replacement, thereby maintaining continuous production flow and high productivity

Inventive Principle:
Principle #20Continuity of useful action

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 eliminates wear and tear on protective devices, ensuring reliable protection against high-power laser pulses and extending the service life by maintaining a constant flow of fluid, which absorbs and dissipates laser energy, preventing damage to the component.

Implementation Method 1

the laser beam after forming of the hole is absorbed by the fluid

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

An alloy selected as the fluid allows for a greater degree of freedom in choosing a suitable melting temperature. An alloy can also be used to set a melting temperature below 30°C

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3870387B1Method for laser drilling a component
Publication Date: 2022.09.07 ROBERT BOSCH GMBH
  • EP3870387B1 patent drawingFigure 1~2
  • EP3870387B1 patent drawingFigure 3~4
  • EP3870387B1 patent drawingFigure 5

AI summary

A method for laser drilling a component (10), in particular an injection nozzle which has a hollow space (15), comprises the steps of producing a metallic fluid (16), injecting the fluid (16) into the hollow space (15), drilling, by means of at least one laser beam, a hole (11) in a wall (12) of the component (10) delimiting the hollow space (15), the laser beam being absorbed by the metallic fluid (16) once the hole (11) is produced, and discharging the fluid (16) from the cavity (15) once laser drilling is completed. An alloy is chosen as the fluid (16).