Flow-Drill Screw Dimple for Heat Transfer and Cycle Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flow-drill screws face challenges in efficiently joining complex products with multiple fasteners and materials, particularly when adhesives are involved, as adhesives can insulate heat transfer and degrade adhesive properties, and differ in thermal conductivity between materials like polymers and aluminum, leading to prolonged cycle times.
Innovation Solution
The method involves forming dimples on parts to facilitate the insertion of flow-drill screws, which creates a heat-focused area above the dimple base, allowing for efficient heat transfer through protrusions and minimizing adhesive insulation, enabling faster and more effective joining by forming a threaded collar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied between parts to be joined, then bonding strength is improved, but heat transfer from the insertion side to the exit side is reduced due to insulative effect
Solution Approach 1:
The protrusion acts as a thermal bridge or intermediary element that conducts heat through the adhesive layer. By creating a localized heat transfer path through the protrusion, the system maintains effective heat transfer despite the presence of adhesive, allowing the adhesive to provide bonding strength without completely blocking thermal conduction.
2Productivity
If high heat is applied to penetrate parts, then joining effectiveness is improved, but adhesive foaming occurs and adhesive properties are degraded
Solution Approach 1:
The protrusion creates a localized heat treatment zone where high heat is concentrated only at the insertion point and immediate surrounding area. This localized heating allows the material to be penetrated and joined effectively while preventing excessive heat from spreading to the adhesive layers, thereby avoiding adhesive foaming and property degradation.
Solution Approach 2:
The protrusion is formed in advance before the joining operation. This preliminary formation of the protrusion structure creates a predefined heat transfer path that controls where heat will be applied during the joining process, ensuring heat is directed to the right location without causing harmful effects to surrounding adhesive.
3Device complexity
If flow-drill screws are used to join multiple parts, then assembly complexity is reduced, but cycle time increases for complex products with large number of fasteners
Solution Approach 1:
The dimple is formed in advance on the part surface before the flow-drill screw insertion. This preliminary dimple formation creates a pre-prepared receptacle that guides the screw tip and concentrates heat at the correct location, enabling faster and more reliable joining operations. By preparing the heat transfer path beforehand, the actual screw insertion and joining process is accelerated.
4Adaptability or versatility
If heat is transferred through polymer parts to aluminum parts, then joining of different materials is achieved, but heat transfer efficiency is reduced
Solution Approach 1:
The protrusion serves as a thermal intermediary that bridges the thermal conductivity gap between polymer and aluminum parts. By concentrating heat at the protrusion tip and creating a direct heat transfer path through the polymer into the aluminum, the system overcomes the poor thermal conductivity of the polymer without requiring excessive heat input.
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 reduces cycle time for flow-drill screw operations by enhancing heat transfer and adhesive penetration, ensuring secure connections without degrading adhesive properties, even across different materials.
Implementation Method 1
The flow-drill screw rotates at high speed (i.e. 5,000 rpm) with a substantial axial force (i.e. 1.5 kN) being applied to the part. The material is heated and softened until it is plastically deformable.
Implementation Method 2
The protrusion penetrates the adhesive that facilitates heat transfer from the protrusion to the second part without the adhesive insulating the second part from heat developed in the protrusion.
Data Source
AI summary
A method of reducing the cycle time required for flow-drill screw operations by providing a dimple on a part that is engaged by a flow-drill screw. A tip of the flow-drill screw engages a contact band at a location spaced from the tip of the distal end of the flow-drill screw and base portion of the dimple. Friction between the flow-drill screw tip and dimple creates a heat concentration area and results in displaced material fanning a threaded collar. The flow-drill screw is secured by the threads of the threaded collar.