Flat-Headed Screw With Segmented Curved Cutting Ribs
Solution Overview
Problem
Existing flat-headed screws with internal cutting ribs face difficulties in being unscrewed from materials once inserted, and they do not provide a clean finish when used in metal-on-wood connections due to poor countersinking and blocking actions.
Innovation Solution
A flat-headed screw design featuring a conical part with curved cutting ribs that extend from the end face to the tip, comprising successive segments with a central recess for easy screwing and unscrewing, and a Torx or inner hexagon profile for secure metal-on-wood applications, ensuring efficient countersinking and easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cutting ribs are provided on the conical part, then material removal is efficient, but the finish is not clean and the head does not position well in metal-on-wood connections
Solution Approach 1:
The conical part is segmented into multiple identical sections around the periphery, each with flat and oblique part-segments. This segmentation creates multiple cutting edges that work simultaneously for efficient material removal, while also distributing the contact points for better positioning in predrilled holes, resulting in both high productivity and good finish quality.
Solution Approach 2:
The cutting ribs are curved rather than straight, following the conical surface geometry. This curvature allows the cutting edges to engage the material more effectively across the conical surface, improving material removal efficiency while maintaining smooth contact with the workpiece for better positioning and finish.
2Ease of operation
If the cutting ribs extend from the end face to the bottom section, then countersinking is effective, but the blocking action prevents easy removal and causes end face breakage
Solution Approach 1:
The conical part is divided into segments separated by cutting ribs, with each segment containing both flat and oblique part-segments. The oblique part-segments create pathways that allow the end face to deform and lift during unscrewing without breaking, maintaining end face integrity while enabling easy removal.
Solution Approach 2:
The screw design allows the end face to dynamically change shape during removal. The oblique part-segments enable the end face to lift and deform elastically as the screw is unscrewed, rather than maintaining a rigid blocked structure. This dynamic behavior prevents breakage while facilitating removal.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a flat-headed screw (1) having a tip (2), a cylindrical shaft (3) with a longitudinal axis around which at least one screw thread (4) extends in a helical manner and a screw head (5) which comprises an end face (6) which is arranged at right angles to the longitudinal axis and a conical part (7) which is directed towards the tip (2), wherein the conical part (7) is provided with a number of curved cutting ribs (8), which are distributed in a peripheral direction and project radially outwards, wherein the conical part (7) comprises a top conical section (7a) which adjoins the end face (6) and a bottom conical section (7b) which adjoins the shaft (3), wherein said cutting ribs (8) extend from the end face (6) in the direction of the tip (2) and wherein the end point (9) of the cutting rib (8) is situated in the bottom section (7b).