Screw Tip Recess Design for Material Ejection

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Solution Overview

Problem

Existing screws with semi-conical tips fail to meet technical requirements as the material accumulating in the recess cannot escape, leading to increased resistance and risk of component bursting during screwing, especially in harder materials.

Innovation Solution

A screw tip design featuring a recess delimited by a flat or curved surface forming an acute angle with the normal plane, inclined in the same or opposite direction of the screw thread, allowing material accumulation and escape, reducing resistance and bursting risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a semi-conical screw tip with a recess is used to reduce material displacement, then screwing resistance is reduced and bursting risk is lowered, but material accumulates in the recess and cannot escape, causing increased resistance and potential component bursting

Engineering Contradiction:
Improvescrewing resistanceVSAvoidcomponent bursting risk
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The screw tip is segmented into multiple functional surfaces: a conical surface for initial penetration, a transverse surface for material collection, and a crucially inclined surface that enables material ejection. This segmentation allows each surface to perform its specific function - the conical surface reduces initial resistance, the transverse surface collects material, and the inclined surface prevents material accumulation by directing it outward, thereby resolving the contradiction between reducing screwing resistance and preventing component bursting.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of having the recess completely enclosed as in conventional designs, the invention inverts the approach by providing an open ejection path through the inclined surface. This inverted design allows material to escape from the recess rather than being trapped, converting the harmful effect of material accumulation into a beneficial ejection mechanism that prevents component bursting while maintaining low screwing resistance.

Inventive Principle:
Principle #13The other way round (Inversion)

2Quantity of substance

If the boundary surface of the recess lies in a plane normal to the screw axis, then the recess can collect material, but the material cannot escape and causes increased resistance and bursting risk

Engineering Contradiction:
Improvematerial accumulation capacityVSAvoidscrewing resistance
Core Design Contradiction:
Quantity of substanceVSForce

Solution Approach 1:

The invention adds a new dimensional aspect to the recess design by introducing an inclined surface that is angled relative to the transverse plane. This dimensional change creates a slope that enables material to escape from the recess under rotational force, transforming the recess from a closed containment space into an open ejection channel. This resolves the contradiction by allowing material accumulation capacity while providing an escape path that prevents excessive resistance buildup.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Length of moving object

If a conical screw tip is used to penetrate the second component, then penetration is achieved, but material must be displaced causing high resistance and component bursting in harder materials

Engineering Contradiction:
Improvescrew tip penetration depthVSAvoidmaterial displacement resistance
Core Design Contradiction:
Length of moving objectVSForce

Solution Approach 1:

The invention extracts the material displacement problem from the screwing process by providing a dedicated collection space (the recess) and an ejection path (the inclined surface). Instead of forcing material aside during penetration, the conical tip deposits material into the recess, and the inclined surface enables its removal. This extraction of the displacement function resolves the contradiction between achieving penetration depth and minimizing material displacement resistance in harder materials.

Inventive Principle:
Principle #2Taking out (Extraction)

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

The design reduces screwing resistance and prevents component bursting by enabling material escape from the recess, optimizing screwing performance in various materials.

Implementation Method 1

The surface is continuously in or continuously opposite to the direction of the screw thread is inclined... the material accumulating in the recess can escape from this recess step out

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP1903224B1Screw for fixing at least a first element to a second element
Publication Date: 2012.02.01 SCHMID SCHRAUBEN HAINFELD
  • EP1903224B1 patent drawingFigure 1~1a
  • EP1903224B1 patent drawingFigure 2~2e

AI summary

The screw (1) has a recess provided at a conical screw tip (16), where the recess extends up to a portion of a stud-bolt (10), which adjoins the screw tip. The recess is limited by a parallel surface (17) that is approximated towards an axis of the stud-bolt. The recess is additionally limited by a flat and/or curved surface (18) that includes a point angle between 5 degree and 45 degree with a normal plane on the axis of the stud-bolt. The flat and/or curved surface is bent towards a direction of a screw thread (15).