Blind Protection Shield for Liquid Jet Guided Laser Beam Stability
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Solution Overview
Problem
At short working distances, the stability of the liquid jet guided laser beam is perturbed due to feedback effects, suction of ablated material, and back-reflected laser and plasma light, leading to reduced nozzle lifetime and machining quality, especially when high optical power is used.
Innovation Solution
A blind protection shield is fixed to the machine head, and a transit-hole is drilled into it using the liquid jet guided laser beam, allowing the beam to pass without hindrance, while minimizing absorption and maintaining stability, and a gas jet is used to surround the liquid jet for additional stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the workpiece is placed close to the nozzle (short working distance), then machining precision is improved, but liquid jet stability is perturbed due to feedback effects and surface wave oscillations
Solution Approach 1:
A protection shield is introduced as an intermediary component between the nozzle and the workpiece. This shield acts as a mediator that blocks harmful feedback effects, surface waves, and ablated material from reaching the nozzle, while still allowing the liquid jet to pass through and perform machining. The shield resolves the contradiction by protecting the liquid jet stability without preventing close-distance machining.
2Productivity
If the workpiece is placed close to the nozzle, then machining efficiency is improved, but ablated material is suctioned and deposited on the nozzle, reducing nozzle lifetime
Solution Approach 1:
The protection shield serves as a physical barrier that prevents ablated material from being suctioned onto the nozzle. It intercepts the harmful particles and debris before they can reach the nozzle orifice, thereby extending nozzle lifetime while maintaining close-working-distance machining operations that provide high productivity.
3Power
If high optical power is used, then machining capability is improved, but back-reflected laser and plasma light increases, further reducing liquid jet stability
Solution Approach 1:
The protection shield converts the harmful back-reflected laser and plasma light into a beneficial protective function. By blocking these reflections, the shield prevents them from causing additional liquid jet instabilities, thereby enabling the use of high optical power for enhanced machining capability without the detrimental feedback effects.
4Stability of the object's composition
If a protection shield is added, then liquid jet stability is improved, but device complexity increases
Solution Approach 1:
The protection shield is designed as a simple, replaceable component that can be easily manufactured and replaced when worn. This approach accepts the added device complexity as a minor trade-off, using a simple sacrificial element (the shield) that protects the more critical and expensive nozzle, thereby maintaining liquid jet stability without requiring complex active control systems.
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 solution enhances the stability of the liquid jet guided laser beam, reduces the risk of ablated material deposition on the machine head, and extends nozzle lifetime, enabling high precision machining with elevated laser power levels.
Implementation Method 1
coupling a laser beam into said liquid jet by means of a coupling unit so as to generate a liquid jet guided laser beam
Implementation Method 2
the water jet serves as a cooling medium for the machined part of the work piece
Implementation Method 3
removes in a very efficient way the ablated material
Implementation Method 4
a laser beam with sufficient high energy for ablating material
Data Source
AI summary
A process for providing a protection against damages in a machine head is claimed. The process comprises the following steps: First a blind steel plate (protection plate 20) is fixed to a protection chamber (10). Then the transparent liquid jet (WJ) guided laser beam (LB) is started, which drills a transit-hole into it. This protection plate (20) has the transit-hole (23) precisely arranged on the optical axis. Therefore no further alignment is required. Further an apparatus for treating a work piece by means of a laser beam (LB) which is guided in a transparent liquid jet (WJ) is claimed. The apparatus comprises a protection chamber (10) mounted on the output (5) of a coupling unit (CU) and a protection plate (20) replaceable fixed to the first chamber (10) protecting the outlet (15) of the first chamber (10) from sputtered debris.