Tapered Self-Tapping Screw Assembly for Fast Watch Plate Fixing
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Solution Overview
Problem
Existing self-tapping screws require a long time for assembly and have poor holding strength due to the gradual tapping process and the need for manual guidance, which is inefficient and prone to errors, especially in compact spaces like watch boxes.
Innovation Solution
A self-tapping screw with a body having variable diameter and a housing with a corresponding shape, allowing the screw to be guided and fixed securely without manual handling, enabling faster and more robust assembly by utilizing a cylindrical section design with a thread that taps the accommodation over its entire length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a self-tapping screw with a smooth first section is used for pre-positioning, then the screw can be guided in the housing, but the screw does not hold well and risks coming out easily
Solution Approach 1:
The screw body is divided into sections with different properties: the first section has threads for retention while the second section is smooth for guidance. This local differentiation allows each section to fulfill its specific function optimally - the threaded first section provides secure holding, while the smooth second section provides guidance during insertion.
2Reliability
If the first section of the screw is made longer to improve holding, then the screw holds better, but the element becomes too thick and takes up too much space
Solution Approach 1:
By providing threads only in the first section rather than along the entire screw body, the design achieves secure retention in a compact length. The threaded first section provides adequate holding strength while the overall screw length remains limited, avoiding excessive thickness and space occupation.
3Ease of manufacture
If traditional self-tapping screws are used, then assembly is simple, but substantial handling time is required for tapping
Solution Approach 1:
The housing is pre-formed with a recess that matches the screw body shape, including the transition from the wider first section to the narrower second section. This preliminary preparation allows the screw to be inserted and tapped in a single continuous motion without requiring separate positioning steps, thereby reducing handling time while maintaining assembly simplicity.
Data Source
Figure 1
Figure 2~3
AI summary
Assembly (10) comprising a support (30) and a plate (20), in particular a support (30) for a watch movement and a plate (20) for a motor (31) of a watch part, as well as means for fixing the support (30) to the plate (20), the fixing means comprising: - a self-tapping screw (11) configured to form a thread when screwed in, the screw (11) comprising a head (12) and a longitudinal body (15), the body (15) comprising an end (19) opposite the head (12) and a thread (9) arranged around the body (15), the body having a diameter that varies along the first axis of the body (15), being wider at the head (12) to a smaller diameter at the end (19), - a first hole (16) passing through the support (30) or the plate (20), - a housing (21) arranged respectively in the plate (20) or the support (30) depending on the arrangement of the first hole (16),the housing (21) having a shape defined by a wall (8) and an opening (7) for receiving the body (15) of the screw (11), such that, the body (15) of the screw (11) passing through the first hole (16), the predefined shape of the housing (21) is threaded, when the screw is screwed into the housing, characterized in that the shape of the housing (21) has a variable width, which is wider at the opening (7) down to a smaller diameter at the bottom (24) of the housing (21), the shape corresponding to that of the body (15) of the screw (11).