Laser Welding Device for Thermoplastic Parts
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Solution Overview
Problem
Conventional laser welding methods for assembling thermoplastic parts, particularly in the automotive industry, face challenges such as visual degradation, reliability issues, and high costs due to complex and inflexible assembly processes, which result in defects and increased machinery complexity.
Innovation Solution
A device and method for laser welding thermoplastic parts that utilize independent adjustment means for precise force application and geometric referencing, along with a controlled air supply to prevent carbonization, ensuring optimal welding quality and flexibility in assembling complex shapes without marking the parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser welding methods are used to assemble thermoplastic parts, then assembly can be performed, but visual degradation and surface defects occur on the transparent part
Solution Approach 1:
The patent segments the clamping function into two independent systems: first clamping means for geometric referencing and second clamping means for force application. This segmentation allows each system to be optimized for its specific function, preventing surface contact that would cause carbonization while ensuring proper welding pressure through the absorbent part.
Solution Approach 2:
The absorbent part serves as an intermediary between the laser beam and the transparent part. It absorbs the laser energy and transmits mechanical pressure without contacting the transparent part's surface, thus preventing carbonization while enabling welding through thermal diffusion at the interface.
2Measurement precision
If geometric referencing is performed on the rigid transparent part, then positioning accuracy is achieved, but the part surface is marked and degraded
Solution Approach 1:
Instead of clamping the transparent part from above (which would contact and mark the surface), the patent inverts the approach by using first clamping means that reference geometry without direct surface contact, and applies force through the absorbent part from below, thus achieving positioning accuracy without surface marking.
3Reliability
If controlled pressurization is adjusted during laser welding, then welding quality is optimized, but device complexity and cost increase significantly
Solution Approach 1:
The patent applies preliminary action by setting the predetermined force through the second clamping means before laser welding begins. This pre-applied pressure is maintained throughout the welding process without requiring active adjustment during welding, thereby optimizing welding quality while avoiding complex real-time pressure control systems.
Solution Approach 2:
The patent changes the parameter of force application from dynamic adjustment during welding to a predetermined static force applied beforehand. This parameter change simplifies the device by eliminating complex control systems while maintaining optimal welding conditions through proper initial force selection.
4Reliability
If complex assembly methods are used for thermoplastic parts, then assembly reliability is improved, but manufacturing cost and machinery complexity increase
Solution Approach 1:
The patent applies universality by designing a support structure that serves multiple functions: positioning the assembly, receiving the absorbent part, and facilitating laser welding. This multi-functional design eliminates the need for separate complex positioning and clamping systems, thereby improving assembly reliability while reducing manufacturing cost and machinery complexity.
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
The solution enables simple, rapid, and efficient assembly of thermoplastic parts with improved reliability and quality, avoiding defects and reducing costs by optimizing force distribution and geometric alignment, while preventing surface carbonization.
Implementation Method 1
A controlled pressurization of the two parts is also provided all along a welding interface while the laser beam travels through this interface. The temperature of the lower absorbent part will then rise until melting and will melt the transparent material of the upper part by diffusion
Implementation Method 2
The temperature of the lower absorbent part will then rise until melting and will melt the transparent material of the upper part by diffusion, creating a permanent weld during the cooling phase
Implementation Method 3
said air supply means makes it possible to avoid a carbonization phenomenon (as described below) on the surface of the assembled parts
Data Source
AI summary
The invention relates to a device (10) for the laser welding assembly of a first upper transparent part (11) to a second lower absorbent part (12), comprising a means (14) for projecting a laser beam (F) onto the upper part (11), first clamping means (15) for geometrically referencing the two parts (11, 12), second clamping means (19) and first adjustment means (20) associated with the second flanging means (19). The first adjustment means (20) comprise a plurality of mobile members (21) which can be actuated independently of one another at a pre-determined welding interface (17) between the two parts (11, 12) and which are used to adjust a pre-determined stress (f2) at said welding interface (17). The assembly method of the invention is intended for the laser-transparent welding of two parts (11, 12) assembled using one such assembly device (10).