Eyeglass Spring Hinge Housing With MIM Recess and Minimal Length

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Solution Overview

Problem

Conventional spring hinge housings for eyeglasses require excessive material and are aesthetically unappealing due to tool run-outs, limiting design freedom.

Innovation Solution

Manufacture the housing body in one piece using metal powder injection molding, ensuring a short length with a steep inner wall and no tool run-out, allowing for a compact design that accommodates the spring hinge mechanism effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional machining methods are used to create the receiving recess, then the spring hinge mechanism can be accommodated, but the housing body must extend far beyond the receiving end to provide tool run-out space

Engineering Contradiction:
ImprovemachinabilityVSAvoidhousing length
Core Design Contradiction:
Ease of manufactureVSLength of stationary object

Solution Approach 1:

The patent changes the manufacturing method from conventional machining to metal powder injection molding. This process parameter change allows the receiving recess to be formed directly during molding without requiring tool run-out space, eliminating the need for the housing to extend beyond the receiving end and achieving minimal housing length while maintaining manufacturability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical machining process with a metal powder injection molding process. This substitution eliminates the need for mechanical tool run-out space required by saws and milling cutters, allowing the housing to be formed with precise dimensions without excessive length extension beyond the functional requirements

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

2Ease of manufacture

If the housing body extends far beyond the receiving end to accommodate tool run-out, then machining can be performed, but unnecessary material is required

Engineering Contradiction:
ImprovemachinabilityVSAvoidmaterial usage
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent changes the manufacturing process from conventional machining to metal powder injection molding, which forms the receiving recess directly during the molding process. This eliminates the need for additional material to create tool run-out space, reducing overall material consumption while maintaining the ability to manufacture the housing

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts and eliminates the unnecessary tool run-out portion from the housing design. By using metal powder injection molding, the housing can be manufactured with the receiving recess formed precisely where needed, removing the excess material that would otherwise be required for machining operations

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If the housing body extends far beyond the receiving end, then the spring hinge mechanism can be received, but the aesthetic appearance is negatively impacted

Engineering Contradiction:
ImprovemanufacturabilityVSAvoidaesthetic appearance
Core Design Contradiction:
Ease of manufactureVSShape

Solution Approach 1:

The patent changes the manufacturing method to metal powder injection molding, which allows the housing to be formed with precise dimensions that match the functional requirements of the spring hinge mechanism. This eliminates the excessive length extension beyond the receiving end, improving aesthetic appearance while maintaining manufacturability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent removes the unnecessary extension of the housing body beyond the receiving end by using metal powder injection molding. This extraction of excess length improves the aesthetic appearance of the housing while preserving the ability to manufacture the component with the required receiving recess

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of manufacture

If the housing body extends far beyond the receiving end, then the spring hinge mechanism can be accommodated, but design freedom is restricted

Engineering Contradiction:
ImprovemanufacturabilityVSAvoiddesign freedom
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent changes the manufacturing process to metal powder injection molding, which provides greater design freedom by allowing the housing to be formed with precise dimensions without being constrained by tool run-out requirements. This enables more versatile and adaptable housing designs while maintaining ease of manufacture

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional machining with metal powder injection molding, which substitutes the mechanical constraints of tool run-out space with a more flexible forming process. This substitution increases design freedom, allowing the housing to be optimized for both function and aesthetics without being restricted by machining requirements

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 reduces material usage, enhances aesthetic appeal, and increases design freedom by minimizing the housing length while maintaining functionality.

Implementation Method 1

manufacture the housing body in one piece using a metal powder injection molding process

Methodology Applied
Scientific EffectMetal powder injection molding:

Data Source

PatentEP3794406B1Housing for a spring hinge of eyeglasses, eyeglasses part having such a housing, and eyeglasses having such an eyeglasses part
Publication Date: 2026.04.15 OBE GMBH & CO KG
  • EP3794406B1 patent drawingFigure 1~2
  • EP3794406B1 patent drawingFigure 3~4

AI summary

The invention relates to a housing (1) for a spring hinge of eyeglasses, having a housing body (3), which has a receptacle recess (5) for receiving a spring hinge mechanism (7) in the receptacle recess (5), wherein the housing (1) has at least one opening (11), communicating with the receptacle recess (5), on an end face (9) of the housing body (3), wherein the receptacle recess (5) has, along a longitudinal extension of the housing body (3) from the at least one opening (11) to a receptacle end (13) facing away from the end face (9), a cross-section suitable for arranging the spring hinge mechanism (7). According to the invention, the housing body (3) is integrally produced in a metal powder injection molding process, and the housing body (3) along the longitudinal extension ends at a maximum distance of 1.15 mm behind the receptacle end (13), and/or the receptacle recess (5) behind the receptacle end (13) in the longitudinal direction is delimited by an inside wall (25), which, together with the longitudinal extension, includes an angle of at least 88° to a maximum of 92°.