Laser-Heated Clinch Nut Joining for Advanced High-Strength Steel
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Solution Overview
Problem
Existing methods for securing clinch nuts to advanced high-strength steel sheets (AHSS) face challenges in efficiently and safely joining these hard-to-work materials, particularly due to the lack of elongation and extreme hardness of AHSS, which makes conventional mechanical joining methods ineffective.
Innovation Solution
The method involves using a controlled laser heating process to make the AHSS sheet more ductile, followed by the use of a pierce clinch nut and a nut ram assembly to securely attach the clinch nut to the sheet. This process is conducted within a light-safe workstation that prevents operator exposure to scattered laser radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical joining methods are used on AHSS sheets, then the joining process is simple, but the method is ineffective due to the extreme hardness and lack of elongation of AHSS
Solution Approach 1:
The patent applies parameter changes by heating the AHSS sheet to elevated temperatures (e.g., austenite transformation range) to alter its material properties. This temporary parameter change increases ductility and reduces hardness, enabling conventional mechanical joining methods to effectively form clinch nuts on the otherwise difficult-to-work AHSS material
Solution Approach 2:
The patent employs preliminary action by performing laser heating of the AHSS sheet before the mechanical joining operation. This preparatory thermal treatment modifies the material state in advance, making the AHSS sheet receptive to subsequent clinch nut formation without requiring complex alternative joining equipment
2Reliability
If laser heating is used to make AHSS more ductile, then the joining effectiveness is improved, but operator safety is compromised due to scattered laser radiation
Solution Approach 1:
The patent converts the harmful scattered laser radiation into a beneficial contained thermal field by using reflective surfaces and enclosed positioning. The workstation design captures and redirects scattered radiation back onto the workpiece or into safe directions, transforming a safety hazard into an additional heating benefit while protecting operators
Solution Approach 2:
The patent introduces an intermediary light-safe workstation structure that physically separates the operator from the laser beam path. This intermediary enclosure with controlled openings and reflective barriers acts as a mediator between the laser heating process and the operator, allowing the thermal process to proceed while blocking harmful radiation exposure
3Object-affected harmful factors
If a light-safe workstation is used to prevent radiation exposure, then operator safety is improved, but the processing complexity increases
Solution Approach 1:
The patent applies universality by designing the light-safe workstation to serve multiple functions simultaneously: it contains scattered laser radiation for safety, provides structural support for positioning components, defines the processing zone, and guides the laser beam through controlled openings. This multi-functionality reduces the need for separate safety devices and simplifies the overall system
Solution Approach 2:
The patent merges the light-safe enclosure structure with the positioning and support functions into a single integrated workstation assembly. By combining safety features with mechanical support and beam guidance elements, the design avoids adding separate complex safety systems, thereby reducing overall processing complexity while maintaining operator protection
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 method effectively secures clinch nuts to AHSS sheets by leveraging laser heating to enhance ductility, allowing for secure attachment without exposing operators to harmful radiation, thus ensuring both efficiency and safety in the joining process.
Implementation Method 1
lasers have previously been used for mechanically joining aluminum and/or magnesium elements using self-piercing rivets with preheating
Data Source
Figure 1
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Figure 3~4
AI summary
Apparatus (20) and a method for securing a clinch nut (24) to an AHSS sheet (26) as an assembly (22). In one embodiment, a parallel kinematic machine (PKM) (88) sequentially performs the operation, while another embodiment includes a nut ram assembly (112) that attaches clinch nuts (24) to the AHSS sheet (26), and a further embodiment includes a C frame (114) that supports the apparatus and is moved by a robot (130) to sequentially attach clinch nuts (24) to the AHSS sheet (26) at different locations. The attachment of the clinch nuts is performed in a light-safe manner.