Laser Deposition Coating with Localized Preheating for Metal Workpieces
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Solution Overview
Problem
High-speed laser deposition welding methods face challenges in achieving precise pre-heating of workpieces without large-scale energy consumption and preventing oxidation, which affects the quality of the coating process, particularly in applications like brake discs.
Innovation Solution
A method involving localized pre-heating and post-heating using multiple laser beams with adjustable intensity distributions and focused energy input to enhance bonding and prevent delamination, eliminating the need for additional pre-heating techniques like induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large-scale induction pre-heating is used to heat the workpiece surface, then the workpiece surface temperature increases to achieve sufficient bonding, but energy consumption increases significantly and the pre-heating temperature cannot be adjusted precisely
Solution Approach 1:
The patent applies local quality by using a laser beam to heat only the specific area where the additional material will be deposited, rather than heating the entire workpiece surface. This localized heating approach reduces energy consumption while maintaining the necessary temperature for bonding in the coating zone.
Solution Approach 2:
The patent implements preliminary action by pre-heating the workpiece surface with a laser beam before introducing the additional material. This ensures the surface reaches the required minimum temperature for sufficient bonding without requiring subsequent large-scale induction heating.
2Temperature
If large-scale induction pre-heating is used to heat the workpiece surface, then the workpiece surface temperature increases to achieve sufficient bonding, but the pre-heating temperature cannot be adjusted precisely
Solution Approach 1:
The patent applies parameter changes by using a laser beam with adjustable power and duration to precisely control the heating process. The laser parameters can be varied to achieve the exact minimum temperature required for bonding, providing precise temperature control that induction heating cannot achieve.
3Temperature
If induction pre-heating is used on brake discs made of gray cast iron, then the workpiece surface is heated, but oxidation occurs above 300°C which negatively affects coating quality
Solution Approach 1:
The patent applies local quality by heating only the specific coating zone with the laser beam rather than the entire workpiece surface. This localized heating prevents excessive temperature rise and oxidation in non-coating areas, while still achieving the necessary temperature for bonding in the targeted zone.
Solution Approach 2:
The patent implements skipping by rapidly heating the surface with a laser beam and immediately depositing the additional material, minimizing the time the surface spends at elevated temperatures. This rapid process prevents oxidation from occurring, unlike slower induction heating methods.
4Productivity
If high-speed laser deposition welding is used to increase machining speed, then productivity increases, but a significant portion of laser power is absorbed by powder flow and metal vapor, requiring additional pre-heating
Solution Approach 1:
The patent implements preliminary action by pre-heating the workpiece surface with the laser beam before introducing the additional material at high speed. This ensures the surface is already at the required temperature when the material is deposited, compensating for the power absorbed by the powder flow and enabling high-speed processing.
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 allows for precise and efficient bonding of additional material to the workpiece surface, reducing energy consumption and minimizing defects like delamination, while maintaining the metallurgical properties of the workpiece.
Implementation Method 1
irradiating a surface of the workpiece by at least one laser beam to generate at least a first irradiation zone and a second irradiation zone on the surface of the workpiece
Implementation Method 2
The additional material at least partially enters the at least one laser beam before impinging on the surface of the workpiece and thereby is at least partially heated
Implementation Method 3
irradiating a surface of the workpiece by at least one laser beam to generate at least a first irradiation zone and a second irradiation zone on the surface of the workpiece
Data Source
AI summary
A method for coating a metal workpiece by laser deposition welding includes moving the workpiece to be coated, and irradiating a surface of the workpiece by at least one laser beam to generate at least a first irradiation zone and a second irradiation zone on the surface of the workpiece. The second irradiation zone precedes or follows the first irradiation zone along a machining direction. The method further includes introducing a powdery additional material into the first irradiation zone. The additional material at least partially enters the at least one laser beam before impinging on the surface of the workpiece and thereby is at least partially heated.