Laser Welding Compressive Force Timing to Prevent Hot Cracks
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Solution Overview
Problem
Existing laser welding methods face issues with material expulsion during heating, leading to seam quality impairment and hot cracking, which are difficult to address with existing methods that often incur high costs or restrict material choices.
Innovation Solution
Applying a compressive force only after the material has melted and before solidification, ensuring stresses are generated at the appropriate temperature to prevent crack formation, and using a rotating device to maintain uniform heat input and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial force is exerted on components during laser heating, then weld seam quality is improved by preventing hot cracks, but liquefied material is expelled from the heating zone impairing seam quality
Solution Approach 1:
The compressive force is applied in advance during the heating phase to prevent hot crack formation, but is removed before solidification begins to avoid material expulsion. This timing-based preliminary action resolves the contradiction by applying the force only when it is beneficial (during heating) and removing it before it becomes harmful (during solidification).
Solution Approach 2:
The compressive force is applied periodically - activated during the heating phase and deactivated during the solidification phase. This periodic application and removal of force allows the system to benefit from crack prevention during heating while avoiding material expulsion during solidification, thus resolving the technical contradiction.
2Reliability
If compressive force is applied during solidification to prevent cracks, then weld seam quality is improved, but material is squeezed or thrown out of the joining zone
Solution Approach 1:
The compressive force is removed before solidification begins, so it is not present during the critical solidification phase when material expulsion would occur. This timing-based preliminary action prevents material loss while still providing crack prevention benefits during the earlier heating phase.
Solution Approach 2:
The compressive force is rapidly removed just before solidification begins, skipping the period when both crack prevention and material retention are critical. This rapid transition allows the system to avoid material expulsion while having already benefited from crack prevention during heating.
3Reliability
If conventional methods are used to prevent hot cracks (pre/post heating, reduced heat input, material restriction), then crack formation is reduced, but implementation cost increases or material choices are restricted
Solution Approach 1:
The compressive force application is made dynamic - it is activated during heating and deactivated during solidification based on the process phase. This dynamic control achieves effective crack prevention without requiring permanent structural modifications, expensive material restrictions, or complex pre/post heating systems, thus maintaining ease of manufacture and material flexibility.
Solution Approach 2:
The timing parameter of compressive force application is changed - it is applied only during the heating phase and removed before solidification. This parameter change allows effective crack prevention to be achieved through simple timing control rather than through expensive structural modifications or material restrictions, maintaining ease of manufacture and material flexibility.
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 prevents material expulsion and minimizes crack formation, achieving high weld seam quality without the drawbacks of existing methods, such as material restriction or high costs.
Implementation Method 1
The material in the joining zone of the two components is heated by means of the laser beam to a temperature which is above the melting temperature of the material
Implementation Method 2
heating of the material in the area of the joining zone, i.e. in the direction from which the laser beam impinges on the two components, takes place over the entire cross-sectional area of the two components until the material is liquefied
Implementation Method 3
the compressive force on the components occurs at most in a period of time between the complete melting of the material of the two components in the joining zone and its solidification
Implementation Method 4
Thermally induced stresses and strains, e.g. shrinkage, cause the formation of fine, interdendritic cavities in the weld metal
Data Source
AI summary
The invention relates to a method for producing a laser weld (1) in which the material of two components (2, 3) is melted in a joining zone (11) by means of a laser beam (100), which then solidifies upon cooling to form the laser weld (1). According to the invention, the laser beam (100) melts the material of the two components (2, 3) in the joining zone (11) at least almost completely across its cross-section, and a compressive force (F) is exerted on the two components (2, 3) at least temporarily during the process, acting at least substantially perpendicular to the plane of the joining zone (11) or perpendicular to the laser beam (100).