Vehicle Light Laser Welding with Localized Fibre Power Control

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Solution Overview

Problem

Conventional simultaneous laser welding techniques for vehicle lights are complex, slow, and costly due to significant light power losses and inability to locally manage light power, especially when dealing with complex shapes, leading to high tooling times and costs.

Innovation Solution

A simultaneous laser welding apparatus using a plurality of laser diodes, each with its own optical fibre, directing light beams through a light guide to individually adjust and focus power at specific points along the welding interface, reducing power losses and allowing for precise energy distribution based on the geometry of the vehicle light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single laser source is connected to a bundle of optical fibres to perform simultaneous laser welding, then the welding can be performed over the whole interface simultaneously, but significant light power losses occur (around 30%) and the light power cannot be locally managed

Engineering Contradiction:
Improvewelding speedVSAvoidlight power loss
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent divides the single laser source system into multiple independent laser diodes (e.g., 3-5 separate laser diodes), each connected to its own optical fibre. This segmentation eliminates the power loss associated with beam splitting in a single bundle while maintaining simultaneous welding capability across the interface. Each laser diode operates independently, delivering full power to its designated region without the 30% loss incurred in traditional bundled approaches.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements local power management by assigning each laser diode to a specific region or point along the welding interface. This allows the light power to be locally adjusted and optimized for each segment of the interface, enabling precise control over the welding process at different locations while maintaining overall simultaneous operation. The system can adapt power distribution to match the specific geometric and material requirements of each local area.

Inventive Principle:
Principle #3Local quality

2Productivity

If a bundle of optical fibres is used to distribute laser beams, then simultaneous welding over the interface is achieved, but the complexity of the apparatus increases and power losses occur

Engineering Contradiction:
Improvesimultaneous welding capabilityVSAvoidoptical fibre bundle complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the complex bundled fibre structure with multiple simple, individual optical fibres, each connected to its own laser diode. This segmentation simplifies the overall system architecture by eliminating the need for complex beam splitting and fibre bundle management, while still achieving simultaneous welding through coordinated operation of multiple independent laser-fibre pairs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple simple laser diode-fibre units into a coordinated system that achieves the functionality of a complex single-source bundle system. By merging several independent, simple components, the system achieves simultaneous multi-point welding without the complexity and power losses inherent in traditional bundled approaches.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If maximum light power is sent to all portions of the welding interface to ensure quality at the most critical point, then welding quality is maintained, but tooling times and costs increase significantly

Engineering Contradiction:
Improvewelding qualityVSAvoidtooling time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local power management where each laser diode's output is independently controlled and optimized for its specific region of the welding interface. This allows the system to deliver appropriate power levels locally rather than uniformly applying maximum power everywhere. Critical areas receive sufficient power for quality welding, while less critical areas receive optimized power levels, reducing overall tooling time and costs while maintaining welding quality where it matters most.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent enables dynamic adjustment of laser power parameters for each individual laser diode based on local requirements. By changing the power parameter locally rather than globally, the system optimizes the balance between welding quality and processing time, avoiding the inefficiency of applying maximum power uniformly across the entire interface.

Inventive Principle:
Principle #35Parameter changes

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 significantly reduces power losses to about 1-2% compared to 30-35% in traditional methods, enables efficient welding of complex geometries, and ensures a mechanically resistant and long-lasting welding joint with localized power control, thereby lowering costs and improving welding quality.

Implementation Method 1

the container body acts as absorbing element towards the light beam emitted by the laser source

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

a plurality of laser diodes (44) suitable for emitting light beams

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 3

The lenticular body substantially transmits the laser beam therein incident without absorbing it

Methodology Applied
Scientific EffectLight transmission: Refraction

Implementation Method 4

The laser beam is absorbed at the welding interface by the perimeter edge of the container body which is heated up to softening

Methodology Applied
Scientific EffectPhotothermal heating: Heating

Data Source

PatentEP3388222B1Simultaneous laser welding apparatus and method of simultaneous laser welding a vehicle light
Publication Date: 2023.09.06 MARELLI AUTOMOTIVE LIGHTING ITAL SPA
  • EP3388222B1 patent drawingFigure 1
  • EP3388222B1 patent drawingFigure 2~3
  • EP3388222B1 patent drawingFigure 4~7

AI summary

A simultaneous laser welding apparatus (36) of a vehicle light (4) comprising a placement support (40) for a container body (8) and a lenticular body (24) of a vehicle light (4) to be welded together at reciprocal perimeter profiles (20,28) associated at a welding interface (32), a plurality of laser sources (34, 44) suitable for emitting light beams, a plurality of optical fibres (48) associated with the laser sources (34, 44) at input ends (52) and suitable for transmitting said light beams, a fibre-holder support device (60) for the optical fibres (48), suitable for blocking output ends (56) of said optical fibres (48) in predetermined positions, spaced apart by a pitch (P), a light guide (64) provided with at least one seat (76) which extends from a light input wall (68), which receives the light beams coming from the output ends (56) of the optical fibres (48), to a light output wall (72) which sends the light beams towards the welding interface (32). Advantageously, a single optical fibre (48) is associated at its input end (52) with each laser source (34, 44) so as to receive, channel and transmit towards the welding interface (32), the light beam produced by said corresponding laser source (34, 44).