Conical Sleeve Bore Connection Without Protruding Fasteners

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Solution Overview

Problem

Existing form-fitting connection elements for component connections, such as those described in DE 2 938 476 A1 and DE 103 08 242 B4, protrude from the bores, requiring additional space, weight, and often seize after years of use, similar to screw connections, which are difficult to loosen.

Innovation Solution

A form-fitting connection element with a conical sleeve and tapered bolt that expands radially to create a press fit within the bore, featuring a structured, rough surface with profile peaks to achieve a form-fitting connection, eliminating the need for protruding screws and nuts, and allowing for easy disassembly and reuse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional screw connection is used, then the connection is secure and reliable, but the connecting elements (screws, nuts) protrude from the bores, requiring additional space and weight

Engineering Contradiction:
Improveconnection reliabilityVSAvoidspace occupied by connecting elements
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The invention extracts the protruding parts (screw heads and nuts) from the connection system by using a form-fit connection element that is completely contained within the bores. The connection element consists of a conical sleeve and tapered bolt that expand radially to create a press fit, eliminating the need for external fastening components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The connection element is nested entirely within the bores of the components being joined. The conical sleeve and tapered bolt are contained within the bore space, with the expanded sleeve filling the bore volume to create a secure fit, similar to nested dolls where one object is contained within another.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If a conventional screw connection is used, then the connection is secure, but the connecting elements have noticeable weight that increases inertia during movements

Engineering Contradiction:
Improveconnection reliabilityVSAvoidweight of connecting elements
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The invention removes the heavy external fastening components (screws and nuts) and replaces them with a compact connection element that uses radial expansion for securing. This extraction of protruding parts significantly reduces the overall weight of the connection system.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a conventional screw connection is used, then the connection can be made securely, but the screws and nuts require additional assembly and disassembly work

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly and disassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The connection element is pre-configured with the conical sleeve and tapered bolt in a compact assembly that can be inserted into the bores as a single unit. The preliminary arrangement of components eliminates the need for separate assembly steps of multiple fastening elements, reducing assembly time and complexity.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If a conventional screw connection is used, then the connection is secure, but the threads can seize up and become difficult to loosen after years of use

Engineering Contradiction:
Improveconnection reliabilityVSAvoidease of disassembly
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention replaces the threaded mechanical system with a radial expansion system. Instead of using threads that can seize due to friction and deformation, the connection element uses a conical sleeve and tapered bolt that create a press fit through radial expansion, eliminating the seizing problem associated with threaded connections.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution provides a secure, resilient connection that saves space and weight, reduces assembly time, and prevents seizing, while maintaining the advantages of screw connections like reduced thread cutting and fewer components, ensuring easy removal and reuse over years.

Implementation Method 1

the conical sleeve between a initial position before the clamping process and a clamping position in the plastic range, with the outer diameter of the cylindrical outer casing having a value D1 in the initial position and a value D2 in the clamping position

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

If an axial tensile force is applied, preferably by a hydraulic clamping device, which pulls the taper bolt relative to the cone sleeve in the direction in which the smallest diameter of the cone sleeve is located, the cone moves relative to the sleeve and spreads it radially outwards

Methodology Applied
Scientific EffectMechanical force transmission: Mechanical Force

Implementation Method 3

The structured, non-smooth surface basically replaces the thread of a screw connection. The local peaks, also called profile crests, which press into or dig into the surface areas of the inner wall of the bore, result in a form-fitting connection

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

The rough surface is defined in that it corresponds to a surface such as sandpaper with a grit between 50 and 1500, in particular between 80 and 1000, according to the grit CAMI

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP3085971B1Positive-fit connecting element for component compounds
Publication Date: 2021.07.28 KOLLGES RALF
  • EP3085971B1 patent drawingFigure 1~4
  • EP3085971B1 patent drawingFigure 5~7

AI summary

A unit consisting of a) a form-fitting connecting element for component connections, which has a conical sleeve (20) which has a conical inner shell (24) and a cylindrical outer shell which has a structured, rough surface with profile peaks (70), and which has a tapered bolt (30 ) which has an outer cone shell (32) which is in planar contact with the conical inner shell (24), from b) an axial clamping device (40), with a relative movement between the cone bolt (30) and cone sleeve (20) during a clamping process takes place and the conical sleeve (20) deforms in the elastic range, and c) a component (56) which has a bore (52) in which the connecting element is located, the inner diameter of the bore (52) being larger in the normal state , but in the tensioned state is smaller than the diameter of the outer jacket, and wherein in the tensioned state of the form-fitting connecting element the profile peaks (70) are at least 3 microns eter penetrated into the material on the inner wall of the bore (52).