Laser Peening Shutter Control for Discontinuous Target Sections
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Solution Overview
Problem
Laser peening devices face challenges in effectively suppressing harmful laser beam irradiation when dealing with discontinuous sections in the target, leading to residual laser light and potential overheating of shutters, due to difficulties in accurately controlling the laser beam blocking mechanism.
Innovation Solution
A laser peening device and method that incorporate an ongoing irradiation sensor to monitor the laser beam's appropriateness and a control unit to immediately suspend irradiation when deviations are detected, using a shutter and adjustable liquid flow to prevent harmful irradiation and overheating, by employing an optical or acoustic sensor to detect discontinuities and an inhibitor fluid to obstruct the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the laser beam irradiation spot becomes large after passing through the focal point, then the laser beam can be left unremoved at a site separated from the irradiation target, but the laser beam irradiation energy density falls down and harmful thermal effect and oxidation arise
Solution Approach 1:
The patent introduces a shutter as an intermediary device positioned in the laser beam path after the focal point. The shutter intercepts and blocks the diverging laser beam before it can reach separated sites on the target, preventing harmful thermal effects and oxidation while allowing the laser to propagate through the focal point during normal operation
Solution Approach 2:
The patent employs sensors (optical or acoustic) to detect the presence of discontinuous sections and provides feedback to the control unit. The control unit then actuates the shutter to block the laser beam when discontinuities are detected, creating a closed-loop control system that prevents harmful irradiation while maintaining normal peening operations
2Object-affected harmful factors
If a laser beam blocking shutter is arranged at the inside or outside of the laser oscillator to prevent harmful irradiation, then harmful laser beam irradiation can be blocked, but it is difficult to satisfactorily block the residual light when discontinuous sections are involved due to positional discrepancies
Solution Approach 1:
The patent positions the shutter downstream from the focal point in the laser beam path, rather than at the laser oscillator. This dimensional relocation allows the shutter to intercept the diverging beam at a point where small positional discrepancies result in complete beam blockage, overcoming the limitations of upstream shutter positioning
3Object-affected harmful factors
If the shutter is held in a closed state for a long period of time to prevent harmful irradiation, then harmful laser beam irradiation can be suppressed, but the shutter becomes overheated
Solution Approach 1:
The patent implements periodic action by opening the shutter during normal laser peening operations and closing it only when discontinuous sections are detected. This intermittent operation allows the shutter to dissipate heat during open periods while still providing protection during closed periods, preventing continuous overheating
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
Effectively suppresses harmful laser beam irradiation and prevents shutter overheating by quickly suspending the laser peening operation when discontinuities are detected, maintaining the desired compressive stress and preventing residual tensile stress formation.
Implementation Method 1
a laser beam having a pulse width of somewhere between about 5 nsec and about 10 nsec is converged to a spot having a diameter of about 1 mm by means of a condenser lens and irradiated onto the surface to be worked
Implementation Method 2
the surface of the material being irradiated with the laser beam absorbs energy and is turned into a plasma state
Implementation Method 3
When the plasma is covered by liquid that is transparent to the wavelength of the laser beam, the plasma is prevented from expanding and the inside pressure of the plasma rises up to about several GPa
Implementation Method 4
Then, a strong shock wave is generated and propagated into the inside of the material to give rise to plastic deformation
Implementation Method 5
employing an optical or acoustic sensor to detect discontinuities
Implementation Method 6
employing an optical or acoustic sensor to detect discontinuities
Implementation Method 7
a shutter and adjustable liquid flow to prevent harmful irradiation
Implementation Method 8
using a shutter and adjustable liquid flow to prevent harmful irradiation and overheating
Data Source
AI summary
A laser peening device includes: a laser oscillator; an irradiation nozzle for irradiating a laser beam onto an irradiation target; an optical transmission unit; a shutter attached to the optical transmission unit; a liquid feeder for supplying the irradiation nozzle with liquid to cause the liquid to flow along an optical path of the laser beam running from the irradiation nozzle to the irradiation target; an ongoing irradiation sensor for obtaining information on ongoing laser beam irradiation indicating whether the laser beam is being appropriately irradiated for execution of ongoing laser peening operation on the irradiation target; and a control unit controlling the shutter according to the information on the ongoing laser beam irradiation obtained by the ongoing irradiation sensor.