Rubber Expansion Press-Fit Joining for Long Hollow Members

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Solution Overview

Problem

Existing methods for joining high-tension steel and aluminum components face challenges such as the formation of fragile intermetallic compounds, limitations in material and shape restrictions, and the need for costly and complex equipment, particularly when joining long members.

Innovation Solution

A method and device using an elastic body to uniformly expand and deform the second member, allowing for improved fitting accuracy and strength without material or shape restrictions, utilizing a cam mechanism to convert vertical forces into horizontal forces for easier handling of long members, and employing a ball screw structure for rotary drive capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional joining methods (screws, welds, adhesives) are used to join members, then structural strength can be achieved, but the process becomes complex, time-consuming, and generates harmful factors such as heat, fumes, and waste materials

Engineering Contradiction:
Improvestructural strengthVSAvoidjoining process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex joining processes (screws, welds, adhesives) from the structural assembly method, replacing them with pre-formed interlocking geometries embedded in the foam material. This removes the need for separate joining operations while maintaining structural integrity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The joining features are pre-formed within the foam material during manufacturing, creating ready-to-engage geometries before assembly. This preliminary action eliminates the need for complex field joining operations and reduces assembly time and complexity.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If conventional joining methods are used, then members can be connected, but the process requires multiple steps and generates harmful factors including heat, fumes, and waste

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidheat, fumes, and waste
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The foam material provides its own joining capability through embedded interlocking geometries, making the material self-sufficient for connection purposes. This eliminates the need for separate joining materials (adhesives, fasteners) and the harmful processes associated with them.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent eliminates waste generation by designing a joining system that uses the foam material itself rather than consuming separate joining materials. The interlocking features are recovered as inherent properties of the foam structure rather than being discarded as waste.

Inventive Principle:
Principle #34Discarding and recovering

3Adaptability or versatility

If multiple separate members are joined together, then structural flexibility is achieved, but the number of joining operations increases complexity and time consumption

Engineering Contradiction:
Improvestructural flexibilityVSAvoidassembly speed
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent divides the structural foam into separate members with predefined interlocking geometries, allowing flexible assembly configurations. Each segment contains built-in joining features that enable rapid connection without complex operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The joining function is merged with the foam material itself rather than being a separate process. The interlocking geometries are combined with the material structure, eliminating the need for separate joining operations and significantly improving assembly productivity.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3603842B1Method and device for joining members
Publication Date: 2026.05.06 KOBE STEEL LTD
  • EP3603842B1 patent drawingFigure 1A
  • EP3603842B1 patent drawingFigure 1B
  • EP3603842B1 patent drawingFigure 2A

AI summary

A method for joining members according to the present invention includes: providing a first member 10, a second member 20, a guide shaft member 38, a rubber member 32, a first plunger 34, a second plunger 35, and a drive mechanism 36; inserting the second member 20 into a hole portion 12a of the first member 10; inserting the guide shaft member 38 into a through-hole 32a of the rubber member 32; inserting the rubber member 32, into which the guide shaft member 38 is inserted, inside the second member 20; arranging an assembly 1 in which the first member 10, the second member 20, the rubber member 32, and the guide shaft member 38 so as to horizontally extend; arranging the assembly 1 so as to be sandwiched by the first plunger 34 and the second plunger 35; and moving the second plunger 35 toward the first plunger 34; compressing the rubber member 32 by the first plunger 34 and the second plunger 35 in a direction where the guide shaft member 38 extends, and expanding the rubber member radially outside the guide shaft member 38; and thus expanding and deforming at least a portion of the second member 20 that is inserted into the hole portion 12ato join the portion to the first member 10 by press-fitting.