Pretensioning Pressure Screw Geometry for Higher Load Transfer
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Solution Overview
Problem
Existing pretensioning elements and screw body elements with pressure screws have limited applicable pretensioning forces, restricting their application range, especially under high loads and in industrial conditions.
Innovation Solution
The design of pretensioning element pressure screws with a threadless shank portion having an outer diameter of 0.95 to 1.5 times the thread portion, combined with a fine pitch thread and specific engagement means, allows for the transfer of high pressure forces and efficient torque application, enabling larger tensioning forces and a broader application range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the outer diameter of the threadless shank portion is increased to transfer high pressure forces, then the force transfer capability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The shank is designed with different outer diameters in different sections: the threaded portion has a smaller outer diameter while the threadless shank portion has a larger outer diameter (0.95-1.5 times the thread portion diameter). This local variation in geometry allows optimized force transfer at the pressure surface without increasing the overall thread size, resolving the contradiction between force capability and structural simplicity.
2Force
If a fine pitch thread is used to maintain large core diameter for high force transfer, then the force transfer capability is improved, but the thread strength and load-bearing capacity may be reduced
Solution Approach 1:
The fine pitch thread is implemented only in the threaded portion where engagement with the nut body occurs, while the threadless shank portion has a larger diameter for force transfer. This localized application of fine pitch threading maintains adequate thread strength during engagement while enabling high force transfer through the larger diameter shank portion.
Solution Approach 2:
The shank is segmented into two distinct portions: a threaded portion with fine pitch threading for engagement, and a threadless shank portion with larger diameter for force transfer. This segmentation allows each portion to be optimized for its specific function without compromising the other.
3Force
If the outer diameter of the threadless shank portion is made larger (0.95-1.5 times the thread portion), then the pressure force transfer is improved, but the manufacturing cost and material usage increase
Solution Approach 1:
The larger outer diameter is applied only to the threadless shank portion where it is needed for pressure force transfer, while the threaded portion maintains a smaller, more economical diameter. This localized approach optimizes force transfer without unnecessarily increasing material usage and manufacturing cost throughout the entire component.
Data Source
AI summary
A pretensioning element pressure screw (11) having a shank (12) which has a first end (13) and a second end (14), opposite the first end (13). Starting from the first end (13), a threaded portion (16), having an outer diameter (D), is formed adjacent a threadless shank portion (21), having an outer diameter (dg). The threadless shank portion (21) extends to the second end (14) of the shank (12). An engagement mechanism (26) for a tool is arranged at the first end (13) of the shank (12). The outer diameter (dg) of the threadless shank portion (21) corresponds to 1.0 times the outer diameter (D) of the threaded portion (16). A pretensioning element and a pretensioning screw body element having a plurality of such pretensioning element pressure screws (11) is also disclosed.