Two-Part High-Strength Screw Coupling for Long Shank Stability

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Solution Overview

Problem

Current high-strength screws with metric ISO or inch threads face challenges in flexible and economic production, particularly in achieving high tensile strength and preventing axial and rotational movement between the head and shank, especially for long and thin screws, which limits their length and quality.

Innovation Solution

A high-strength screw design featuring a head and shank as separate material parts with a coupling recess and element, where the axial force transmission element and torque transmission element prevent axial movement and ensure torque transmission, allowing for a two-piece connection that can only be separated destructively, enabling economic and high-quality production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional multi-stage pressing is used to produce high-strength screws, then the production process is established, but the manufacturing precision and quality are limited due to buckling resistance issues

Engineering Contradiction:
ImprovequalityVSAvoidproduction process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The screw is divided into two separate parts: a head made from a head blank and a shank made from a shank blank. These parts are manufactured separately and then connected through a coupling mechanism, allowing each part to be optimized independently and avoiding the limitations of traditional multi-stage pressing of a single piece.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling element is inserted into the coupling recess, with the coupling element being received within the head structure. This nested arrangement allows for precise alignment and connection while maintaining compact dimensions and high manufacturing precision.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Length of moving object

If the screw is designed as a single piece, then the structure is simple, but the length is limited due to buckling resistance issues

Engineering Contradiction:
Improvescrew lengthVSAvoidbuckling resistance
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

By segmenting the screw into head and shank portions manufactured separately, the shank can be made longer without compromising buckling resistance, as each segment can be optimized for its specific function and structural requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection between head and shank uses a composite coupling mechanism involving a coupling recess and coupling element, creating a composite structure that combines the strengths of both parts while maintaining overall structural integrity and resistance to buckling.

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If the head and shank are connected traditionally, then the connection is established, but axial and rotational movement cannot be prevented

Engineering Contradiction:
Improveconnection stabilityVSAvoidcoupling mechanism complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The coupling mechanism is segmented into distinct functional elements: axial force transmission elements for preventing axial movement and torque transmission elements for preventing rotational movement. This segmentation allows each element to be optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The coupling element acts as an intermediary component that mediates the connection between the head and shank. It transmits both axial forces and torque while preventing relative axial and rotational movement, serving as a mediator that achieves stable connection through its specific geometric design.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Ease of manufacture

If high-strength screws are produced with traditional methods, then the basic function is achieved, but manufacturing costs are high and flexibility is limited

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidmanufacturing costs
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

Manufacturing the head and shank as separate components allows for independent production optimization, standardized coupling mechanisms, and flexible assembly, reducing overall manufacturing costs and increasing production flexibility compared to traditional single-piece high-strength screw production.

Inventive Principle:
Principle #1Segmentation

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 the production of high-strength screws with improved tensile strength, reduced manufacturing costs, and increased quality by eliminating the limitations of traditional multi-stage pressing and buckling resistance issues, enabling standardization and efficient production of long screws.

Implementation Method 1

The axial force transmission element and the axial force transmission counter-element are designed and arranged in such a form-fitting manner that they engage in one another in such a way that an axial translational movement of the head relative to the shank is prevented

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The torque transmission element and the torque transmission counter-element are designed and arranged so that they engage in one another in such a way that a rotational movement of the head relative to the shank in the tightening direction of rotation of the thread is prevented by friction

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3837065B1Two-part high-strength screw
Publication Date: 2021.12.29 KAMAX HLDG GMBH & CO KG
  • EP3837065B1 patent drawingFigure 1
  • EP3837065B1 patent drawingFigure 2
  • EP3837065B1 patent drawingFigure 3

AI summary

High-strength screw (1), comprising a head (2) with a tool-engaging contour (4) and a shank (3) with a free end (5) pointing away from the head (2), wherein a threaded portion (6) with a thread (7) is arranged on the shank (3), wherein the thread (7) is formed as a metric ISO thread or an inch thread, wherein the head (2) and the shank (3) are formed as parts of separate materials, the head (2) has a coupling recess (8) arranged radially on the inside and comprising an axial force transmission element (9) and a torque transmission element (10), the shank (3) has a coupling element (11) arranged radially on the outside, on its outer circumference, and comprising an axial force transmission counterelement (12) and a torque transmission counterelement (13), the coupling element (11) engages in the coupling recess (8), the axial force transmission element (9) and the axial force transmission counterelement (12) are formed and arranged as engaging in one another in a form-fitting manner in such a way that an axial translational movement of the head (2) in relation to the shank (3) in a direction away from the free end (5) of the shank (3) is prevented, in particular such that they cannot come apart, and the torque transmission element (10) and the torque transmission counterelement (13) are formed and arranged as engaging in one another in such a way that a rotational movement of the head (2) in relation to the shank (3) in the sense of the rotational direction for tightening the thread (7) is prevented.