Conical Screw-Driving Lobes for Torque and Stick Fit
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Solution Overview
Problem
Conventional screwing tools with conical geometries have failed to gain market traction due to insufficient comfort of use, inability to transmit high torque, and lack of a convincing stick fit effect, despite attempts to address these issues through various design modifications.
Innovation Solution
A screwing tool with a conical transmission part featuring a smaller cone angle at the joining regions compared to the tangential portions, allowing for increased torque transmission and improved self-guiding, while maintaining a larger cone angle at the tangential portions for enhanced comfort and guiding, and a screw with complementary geometry to facilitate efficient stick fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conical surfaces with large inclination angles are used in the transmission lobes, then torque transmission capability is improved, but the stick fit effect (adhesion between tool and screw) deteriorates
Solution Approach 1:
The patent applies different cone angles to different regions of the transmission lobe: a larger cone angle (15-30 degrees) in the distal tangential portion for torque transmission, and a smaller cone angle (0-5 degrees) in the joining region for stick fit effect. This local differentiation allows each region to optimize its function without compromising the other.
2Ease of manufacture
If flat surfaces are used instead of curved surfaces in the transmission lobes, then manufacturing simplicity is improved, but the tool guiding capability and resistance to brittle failure deteriorates
Solution Approach 1:
The patent specifies that the distal tangential portion of each transmission lobe extends substantially according to an arc of a circle, creating a curved surface that provides gradual engagement with the screw head. This curvature improves self-guiding capability and distributes contact stresses, preventing brittle failure while remaining manufacturable.
3Manufacturing precision
If sharp edges are created on the transmission lobes for precise geometry, then manufacturing precision is improved, but the tool becomes more susceptible to brittle failure and harmful to screw recess guiding
Solution Approach 1:
The curved arc-shaped distal tangential portion eliminates sharp edges by providing a gradual transition surface. This curvature maintains precise geometric control during manufacturing while distributing contact stresses to prevent brittle failure and improve guiding without creating harmful sharp features.
4Force
If the cone angle of joining regions is increased to match the tangential portions, then torque transmission uniformity is improved, but the stick fit effect and insertion comfort deteriorates
Solution Approach 1:
The patent differentiates the cone angle between the distal tangential portion (15-30 degrees for torque transmission) and the joining region (0-5 degrees for insertion). This local differentiation ensures that the joining region provides gentle guidance and stick fit effect, while the distal portion handles torque transmission uniformly.
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
The solution provides a screwing tool capable of transmitting high torque with improved comfort and versatility across different screw dimensions, achieving a strong and convenient stick fit effect without compromising torque transmission.
Implementation Method 1
the inclinations of the different surfaces of the tool which are designed to come into contact with the surfaces of the screw are too large in relation to the longitudinal axis of the screw, in order for a stick fit effect (adhesion between the tool and the screw by friction) to be able to be obtained
Data Source
AI summary
The invention relates to a screwing tool with a longitudinal axis X comprising a first, drive part, which can receive torque, and a second, transmission part, which is designed to cooperate with a screw, in order to re-transmit to it the torque received, the second part having a conical peripheral envelope with three longitudinal concavities with conical generatrices, defining three identical radial transmission lobes, each of which has, in a cross-section perpendicular to the longitudinal direction, a distal tangential portion which extends according to an arc of a circle, and is extended on both sides by two connection portions, each of which is defined by a curve comprising a substantially radial main part, and having a point of inflection before re-joining a proximal joining region which ensures the joining with an adjacent connection portion. The joining regions have a cone angle which is smaller than the cone angle of the tangential portions, and is substantially less than 5°, preferably less than 3°.