Washer Coupling Sleeve for Post-Thread-Rolling Screw Assembly
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Solution Overview
Problem
Existing screw fastener designs with integrated washers face issues such as damage during thread rolling, increased production costs, and inefficiency in small batch production, as washers are often damaged or require large batch production to be economically viable.
Innovation Solution
A screw fastener with a coupling sleeve having a U-shaped profile and radially outward flanges, featuring elastically adjustable clamping catches that engage in an undercut of the screw shank, allowing the washer to be securely attached after thread rolling and optionally removable with sufficient force, enabling production without pre-attached washers and suitable for small batches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If washers are fitted onto the screw shank before thread rolling, then the washer is securely retained on the screw, but the washer is damaged during the thread rolling process
Solution Approach 1:
The solution separates the washer retention function from the thread rolling process by using a coupling sleeve as an intermediate component. The coupling sleeve is fitted onto the screw shank before thread rolling and retains the washer after thread rolling, thus segmenting the process into two independent stages: (1) coupling sleeve installation and thread rolling, and (2) washer attachment. This resolves the contradiction by allowing the washer to be securely retained without being present during the damaging thread rolling process.
2Reliability
If washers are pre-attached to screws, then washer retention is improved, but production costs increase due to the need to produce screws with varied lengths and corresponding washer quantities
Solution Approach 1:
The coupling sleeve acts as a universal intermediate component that can be fitted onto screws of any length before thread rolling. This segmentation allows the manufacturing process to be standardized: all screws of a given nominal diameter can be produced with the same coupling sleeve and washer combination, regardless of screw length. This resolves the contradiction by enabling modular assembly that reduces production complexity and cost.
Solution Approach 2:
The coupling sleeve serves multiple functions: it retains the washer on the screw shank, protects the washer during thread rolling, and provides a standardized interface for washer attachment regardless of screw length. This multi-functionality resolves the contradiction by creating a universal solution that works across different screw specifications, thereby reducing the need for multiple specialized washer-screw combinations and lowering production costs.
3Reliability
If washers are pre-attached to screws, then washer retention is improved, but production efficiency decreases for small batch production
Solution Approach 1:
The coupling sleeve enables a segmented manufacturing approach where the washer retention function is decoupled from the screw production process. For small batch production, this allows screws to be produced first, then coupled with washers only when needed. This resolves the contradiction by providing flexibility: the same coupling sleeve mechanism works efficiently for both large-scale and small-scale production, eliminating the need for pre-attachment investment and enabling on-demand washer attachment.
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 design allows for independent thread production without pre-attached washers, reduces production costs, and ensures secure washer attachment without damage, making it suitable for small batch production while maintaining washer security and optional removability.
Implementation Method 1
a plurality of clamping catches projecting radially inward and elastically adjustable in the direction of their longitudinal axis against the interior wall of the coupling sleeve
Data Source
AI summary
A screw fastener arrangement comprising a screw fastener, with a head and a shank, and at least one washer on the shank. A coupling sleeve is in the washer opening through which the shank passes, the coupling sleeve having a U-shaped profile which opens radially outward and is formed by two flanges spaced from each other and protruding radially outward, the coupling sleeve being held interlockingly with the at least one washer by the flange in the direction of the longitudinal axis of the washer opening. The coupling sleeve has clamping catches projecting radially inward and elastically adjustable in the direction of their longitudinal axis against the interior wall of the coupling sleeve, which, using their free end, engage in an undercut of the screw fastener, acting in a longitudinally axial direction to the coupling sleeve. Also disclosed is a washer assembly for such an arrangement.