Multi-start Flow Drill Screw for One-sided Fastening
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Solution Overview
Problem
In industries that rely on assembling components via fasteners, such as the automotive industry, the efficiency of the fastening process is hindered by the time-consuming and multi-step process of inserting fasteners, which can be automated or manual, and the need for forming pilot holes and tapping receiving holes.
Innovation Solution
A fastening device featuring multiple intertwined helical ridges and flow drill features that softens the workpiece material to create a hole and threads, allowing for one-sided access and eliminating the need for pre-drilled holes or securing nuts, thereby reducing the number of rotations required for full insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditionally threaded fastener is used, then the fastening process is simple, but the insertion time is long due to the single helical ridge requiring many rotations
Solution Approach 1:
The single helical ridge is segmented into multiple intertwined helical ridges (first, second, and optionally third ridges) that operate simultaneously. This segmentation allows multiple threads to engage the workpiece material at different locations along the insertion path, effectively parallelizing the thread formation process and reducing the total rotation time required for complete insertion.
2Productivity
If multiple process steps are used (pilot hole formation, tapping, nut application), then each step can be performed with simple tools, but the overall process time increases significantly
Solution Approach 1:
The functions of pilot hole formation, thread tapping, and fastener insertion are merged into a single integrated operation. The flow drill tip creates the hole while the multiple helical ridges simultaneously form the threads during the same insertion motion, eliminating the need for separate pilot hole drilling and tapping steps, and removing the requirement for securing nuts on the opposite side.
3Loss of time
If a flow drill screw with multiple helical ridges is used, then the insertion time is reduced, but the device structure becomes more complex
Solution Approach 1:
Different portions of the fastener are assigned different functional qualities: the flow drill tip is optimized for hole formation through material softening, while each helical ridge is configured with specific pitch and depth characteristics suited for its thread formation function. This local optimization allows each component to perform its specific function efficiently without requiring the entire device to be overly complex.
4Adaptability or versatility
If access is required from both sides of the workpiece, then secure fastening can be achieved, but processing flexibility is reduced
Solution Approach 1:
The fastener performs its own securing function through the material flow and extrusion process. As the multiple helical ridges rotate and advance, they extrude the softened material to form a hollow extrusion that locks the fastener in place, eliminating the need for a separate securing nut on the opposite side. The fastener essentially secures itself during the insertion 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
This solution significantly reduces the time and steps involved in the fastening process, enhancing processing flexibility and efficiency by allowing for faster assembly with fewer steps, while also providing a hollow extrusion that adds strength to the joint.
Implementation Method 1
heat generated by friction from the rotating flow drill screw causes material of at least one of the first and second workpieces to soften
Implementation Method 2
such softened material flows out of the through-draft to form a hollow extrusion
Data Source
AI summary
A fastening device for reducing the time required for insertion that includes an elongated shank portion extending longitudinally between a first and a second shank end; and a head portion arranged at the second shank end, wherein the head portion includes a drive arrangement configured and arranged for receiving a rotary driving force to drive the fastening device into at least one workpiece. The elongated shank portion includes a plurality of intertwined helical ridges (plural thread starts). Preferably, the tip portion is configured and arranged to create a hole and threads by softening the material of a workpiece. Additionally, a method for creating an assembly by attaching a first workpiece to a second workpiece via the use of such a fastening device.