Countersunk Screw Head with Segmented Cutting Edge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional countersunk screws can damage prefabricated countersink surfaces on metal attachments, particularly coatings for corrosion resistance, when screwed in, and fail to create a countersink effect in soft materials like wood.
Innovation Solution
The countersunk screw design features a leading surface inclined radially inward with a cutting edge that maintains a radial distance from the countersink surface, preventing contact and damage, while allowing the head to create a countersink in soft materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cutting edge delimits the support surface (conventional design), then the screw can effectively countersink into soft materials, but the cutting edge damages the prefabricated countersink surface and its coatings on metal attachments
Solution Approach 1:
The head underside is segmented into two distinct functional areas: a leading surface with a cutting edge for creating countersinks in soft materials, and a support surface that contacts the prefabricated countersink in metal attachments. This segmentation allows each area to perform its specific function without interfering with the other, resolving the contradiction between countersink creation capability and surface protection.
Solution Approach 2:
Different regions of the head underside are given different geometric properties: the leading surface has an inclined configuration with a cutting edge optimized for material removal in soft substances, while the support surface is designed to match the prefabricated countersink geometry for precise contact in metal attachments. This local differentiation enables the single component to adapt to different material types and attachment scenarios.
2Reliability
If the cutting edge is positioned to create a countersink effect in soft material, then effective countersinking is achieved, but the cutting edge contacts and damages the prefabricated countersink surface
Solution Approach 1:
The head underside is divided into a leading surface with cutting edge and a separate support surface. The leading surface with its cutting edge is responsible for creating the countersink effect in soft materials, while the support surface is positioned to contact the prefabricated countersink in metal attachments without the cutting edge interfering. This spatial segmentation ensures both functions are performed reliably without mutual interference.
Solution Approach 2:
The solution introduces a radial distance dimension between the cutting edge and the support surface contact area. By positioning the cutting edge at a radial distance from the support surface, the design creates a dimensional separation that prevents the cutting edge from contacting the prefabricated countersink surface while still allowing the leading surface to create the necessary countersink effect in soft materials.
Data Source
Figure 1~6
Figure 7~9
AI summary
The invention relates to the head of a countersunk screw with a lower side which has at least one supporting surface (2), which forms part of a rotational surface about the screw axis (7) and can nestle against a correspondingly contoured countersunk surface (11) of an add-on part (10), and has at least one depression (6) which is delimited by a cutting edge (4) at its end which runs downwards, as seen in the screwing-in direction (e) of the countersunk screw. The invention is distinguished in that in front of the supporting surface (2), as seen in the screwing-in direction (e), there is an approach surface (3) which butts against said supporting surface, is inclined radially inwards and, at its upwardly running, free end, has the cutting edge (4) which, over its length, maintains a radial distance (a) from the rotational surface to the inside.