Tapered Lobular Driver for Multi-Size Fastener Torque Without Cam-Out
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Solution Overview
Problem
Existing torque transmission drivers are limited in their ability to efficiently drive multiple sizes of fasteners, often leading to inefficiencies, mis-installations, and increased risk of cam-out, especially with small fasteners, due to their design limitations and susceptibility to rotational lifting movements.
Innovation Solution
A torque transmission driver with a tapered bit featuring alternating series of lobes and troughs with a taper angle between 15° and 45°, allowing engagement with multiple fastener sizes, and a drive side transition angle between 0° and 5° to prevent cam-out, enabling effective torque transmission across various fastener sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driver is designed for a specific fastener size, then torque transmission is reliable, but the driver can only drive one size of fastener
Solution Approach 1:
The driver bit is designed with a tapered shank and alternating lobes and flutes geometry that allows it to engage multiple fastener sizes (e.g., both #6 and #8 screws) while maintaining reliable torque transmission. The universal design enables a single driver to perform the function of multiple dedicated drivers.
2Adaptability or versatility
If a driver with larger lobes is used to drive a smaller fastener, then the driver can engage the fastener, but the driver cannot seat properly and cam-out occurs
Solution Approach 1:
The driver bit incorporates a tapered shank that allows the engagement geometry to dynamically adapt to different fastener sizes. The taper enables the lobes to properly seat on smaller fasteners by reducing the effective engagement diameter, while maintaining full engagement on larger fasteners, thus preventing cam-out across the size range.
3Adaptability or versatility
If a driver with smaller lobes is used to drive a larger fastener, then the driver can engage the fastener, but the driver cams out and cannot transmit full torque
Solution Approach 1:
The tapered shank geometry allows the driver to dynamically adjust its engagement characteristics. When driving larger fasteners, the full diameter of the lobes engages, maximizing torque transmission capacity. The taper ensures that the lobe-flute engagement geometry scales appropriately with fastener size, preventing cam-out and maintaining full power transmission.
4Adaptability or versatility
If a driver set is maintained for multiple fastener sizes, then all fastener sizes can be driven, but assembly efficiency decreases due to driver changes
Solution Approach 1:
The tapered lobular driver provides a universal solution that eliminates the need for multiple dedicated drivers. A single driver bit can drive multiple fastener sizes, allowing assemblers to remain at their stations and continuously drive fasteners without leaving to retrieve different sized drivers, thus maintaining high assembly efficiency.
5Adaptability or versatility
If a driver attempts to drive a fastener of incorrect size, then the driver may engage, but mis-installation and failure risk increases
Solution Approach 1:
The tapered geometry provides dynamic adaptation that ensures proper engagement only within the designed size range. The taper angle and lobe geometry are configured so that fasteners within the target size range (e.g., #6 and #8) achieve proper seating and torque transmission, while fasteners outside this range naturally fail to engage properly, providing a built-in mechanism to prevent mis-installation.
Data Source
Figure 1A~1D
Figure 2~5
Figure 6~7
AI summary
A torque transmission driver has a first end portion adapted to receive and transmit torque from a torque generation source, and a second end portion including a shaped tapered bit having drive surfaces with an alternating series of five or six lobes and troughs about a rotational axis, having a taper angle between 15 and 45 from the rotational axis operable to engage corresponding drive surfaces in a plurality of at least two size fasteners, the tapered drive surfaces of the bit comprising a first tapered portion operable to engage drive surfaces of a first sized fastener and a second tapered portion operable to engage drive surfaces of a second sized fastener, the drive surfaces of the second sized fastener being larger than the drive surfaces of the first sized fastener.