Tapered Lobular Bit Geometry to Reduce Cam-Out Across Fastener Sizes
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Solution Overview
Problem
Existing torque transmission drivers are limited in their ability to efficiently drive multiple sizes of fasteners without cam-out, inefficiency, and increased misinstallation due to dedicated driver sizes and susceptibility to damage, especially in small fasteners.
Innovation Solution
A torque transmission driver with a tapered bit having alternating lobes and troughs with a taper angle between 15° and 65°, capable of engaging multiple fastener sizes, and a fastener system with similar tapered drive surfaces, reducing the likelihood of cam-out and allowing a single driver to be used for various sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated driver sizes are used for each fastener size, then torque transmission reliability is improved, but device complexity and loss of time increase due to maintaining multiple drivers
Solution Approach 1:
The driver bit is designed with a tapered geometry that allows a single driver to engage multiple fastener sizes. The taper angle of 15°-65° enables the driver to self-align and transmit torque reliably across different fastener dimensions, eliminating the need for multiple dedicated driver sizes while maintaining torque transmission reliability
2Adaptability or versatility
If multiple driver sizes are maintained, then adaptability to different fastener sizes is improved, but loss of time and productivity decrease due to retrieving and changing drivers
Solution Approach 1:
A single tapered driver bit can engage multiple fastener sizes within the tapered geometry range, eliminating the need to switch between multiple dedicated drivers. This universal design maintains adaptability to different fastener sizes while significantly improving productivity by removing driver changeover steps
3Ease of manufacture
If traditional drive systems are used, then ease of manufacture is improved, but object-generated harmful factors increase due to cam-out and driver damage
Solution Approach 1:
The driver and fastener features utilize asymmetric tapered geometries with specific taper angles (15°-65°) that prevent cam-out by ensuring the driver bit self-centers and maintains stable engagement. The asymmetric lobe configurations create mechanical interference that prevents rotational lifting while remaining manufacturable through standard forming processes
4Loss of substance
If small fastener sizes are used, then loss of substance and weight are reduced, but reliability decreases due to increased susceptibility to cam-out and deformation
Solution Approach 1:
The tapered asymmetric geometry provides enhanced mechanical interference and self-centering action that prevents cam-out even in small fastener sizes. The specific taper angles create sufficient engagement surface area and mechanical advantage to maintain reliable torque transmission in miniaturized fasteners without increasing material usage
5Power
If drive angle is reduced to zero, then torque transmission efficiency is improved, but adaptability to different fastener sizes decreases
Solution Approach 1:
The driver features a continuous taper angle of 15°-65° along its length, allowing different sections of the driver to engage fasteners of different sizes while maintaining effective torque transmission. The parameter variation in taper angle enables both high torque efficiency and multi-size adaptability simultaneously
Data Source
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 65° 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. The taper angle may be nominally 52° from the rotational axis.