Laser Welding Pressure Control for Resin Joint Quality
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Solution Overview
Problem
Existing laser welding technologies for resin members face issues with excessive clamping force leading to burrs or cracks, insufficient pressing resulting in inadequate melting and carbonization, and difficulty in real-time adjustment of clamping force due to subtle temperature changes.
Innovation Solution
A laser welding apparatus with a clamping unit, laser emitter, displacement sensor, and control unit that continuously adjusts clamping force and laser output based on real-time displacement measurements to match the state of resin members during welding, using a contact-type displacement sensor for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If clamping force is increased to ensure sufficient pressing of resin members, then welding quality improves, but excessive burrs and cracks form due to residual stress
Solution Approach 1:
The clamping force is changed from a static fixed value to a dynamic variable that adjusts in real-time during the welding process. The control unit modifies the clamping force based on feedback from the displacement sensor, allowing the system to optimize pressing force at different stages of welding while preventing excessive force that causes burrs and cracks.
Solution Approach 2:
A displacement sensor monitors the displacement of the resin members during welding and feeds this information back to the control unit. The control unit uses this feedback to adjust the clamping force dynamically, ensuring optimal pressing force is applied throughout the welding process without causing harmful effects.
2Object-generated harmful factors
If clamping force is decreased to avoid excessive burrs and cracks, then residual stress reduces, but insufficient pressing causes fine gaps and inadequate heat transfer
Solution Approach 1:
The clamping force transitions from a static low value to a dynamic variable that adjusts in real-time. During different stages of welding, the control unit modifies the clamping force to maintain optimal contact between resin members, ensuring sufficient heat transfer while minimizing residual stress.
Solution Approach 2:
The displacement sensor provides continuous feedback on the contact state between resin members. The control unit uses this information to adjust the clamping force, ensuring that sufficient pressing force is applied to maintain good thermal contact without creating excessive residual stress.
3Reliability
If fixed clamping force is applied before laser welding, then initial contact is ensured, but real-time adjustments cannot accommodate thermal expansion of the laser beam-absorbing resin
Solution Approach 1:
The clamping force system transitions from a static pre-set value to a dynamic variable that can adapt in real-time. The control unit modifies the clamping force during welding to accommodate thermal expansion of the laser beam-absorbing resin, maintaining optimal contact conditions throughout the process.
Solution Approach 2:
The displacement sensor continuously monitors the displacement caused by thermal expansion and provides feedback to the control unit. The control unit adjusts the clamping force in response to this feedback, ensuring that the system adapts to real-time changes in the resin members during welding.
4Temperature
If temperature-based control is used to adjust clamping force, then thermal state monitoring is achieved, but control accuracy is reduced due to subtle temperature changes
Solution Approach 1:
The control system replaces temperature-based sensing with displacement-based sensing. The displacement sensor directly measures the physical displacement of the resin members, providing more precise and immediate feedback compared to temperature measurements, which are subtle and slower to respond.
Solution Approach 2:
The control parameter is changed from temperature to displacement. By monitoring displacement instead of temperature, the system achieves higher measurement precision and faster response time, as displacement changes are more pronounced and immediate during the welding process.
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 apparatus effectively limits burrs and cracks, ensures adequate melting, and prevents carbonization by dynamically adjusting clamping force and laser output, improving the quality of the welding process.
Implementation Method 1
a displacement sensor that measures displacement of at least one of the first contact surface or the second contact surface in a direction in which the first resin member and the second resin member are arranged one upon the other
Implementation Method 2
The other one of the two resin members is formed of a laser beam-absorbing resin that absorbs laser beams. The laser beam-absorbing resin member is thermally expanded when absorbing a laser beam during laser welding.
Implementation Method 3
a laser emitter that emits a laser beam transmitted through the first resin member... by melting the first contact surface and the second contact surface with a laser beam
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A first resin member (11) including a first contact surface (12) and formed of laser beam-transmissive resin and a second resin member (21) including a second contact surface (22), which contacts the first contact surface (12), and formed of laser beam-absorbing resin are arranged one upon the other. A laser welding apparatus (1) includes a clamping unit (31) abutting the second resin member (21) and applying clamping force to the second resin member (21), a laser emitter (32) emitting laser beam (Lw), a laser controller (33) controlling output of the laser beam (Lw), a displacement sensor (34) measuring displacement of the second contact surface (22) in stacking direction (X1) of the resin members (11, 21), and a control unit (35) controlling the clamping unit (31) to adjust the clamping force corresponding to displacement amount of the second contact surface (22) continuously or intermittently obtained from the displacement sensor (34).