Coupling Bolt with Concave Recess for Weight Reduction

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Solution Overview

Problem

Coupling bolts in movable joint devices, particularly in drive joints of piston units in machine tools, face challenges in achieving a balance between weight reduction and maintaining resilience, leading to increased inertial forces and vibrations during oscillating movements.

Innovation Solution

The coupling bolt design features a longitudinal extent with a transverse receiving bore, a concave base with a saddle-shaped surface profile, uniform wall thickness, and a metallic material composition, such as aluminum or magnesium-based alloys, to minimize weight while enhancing load-bearing capacity and reducing inertial forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the coupling bolt is made with a cylindrical basic shape and subsequent drilling or milling of the receiving bore, then the manufacturing process is simple, but the weight is high and resilience is reduced

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidcoupling bolt weight
Core Design Contradiction:
Ease of manufactureVSWeight of moving object

Solution Approach 1:

The coupling bolt is segmented into a basic cylindrical body and a recess portion that extends into the interior. This segmentation allows the recess to be formed as an integrated feature rather than through subsequent drilling or milling, reducing weight while maintaining manufacturing simplicity through processes like metal injection molding.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the manufacturing parameters by forming the recess as an integral part of the coupling bolt during the primary manufacturing process, rather than through secondary operations. This parameter change enables weight reduction while maintaining ease of manufacture through appropriate process selection.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If the coupling bolt weight is reduced, then the inertial forces during oscillating movements are reduced, but the resilience and load-bearing capacity may be compromised

Engineering Contradiction:
Improvecoupling bolt weightVSAvoidload-bearing capacity
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The recess is designed with specific local qualities including a concave base with saddle-shaped surface profile and optimized wall thickness distribution. This local quality optimization reduces weight in non-critical areas while maintaining strength in load-bearing regions, achieving weight reduction without compromising load-bearing capacity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The coupling bolt is made from metallic materials such as aluminum or magnesium-based alloys, which provide high strength-to-weight ratio. This material selection enables weight reduction while maintaining or enhancing resilience and load-bearing capacity compared to traditional materials.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If the coupling bolt has a recess with conical bottom produced by subsequent turning, then the manufacturing process is simple, but the weight is not minimized and the surface profile is not optimized

Engineering Contradiction:
Improverecess production simplicityVSAvoidcoupling bolt weight
Core Design Contradiction:
Ease of manufactureVSWeight of moving object

Solution Approach 1:

The recess is designed with a concave base that has a saddle-shaped surface profile with specific curvature characteristics. This curved geometry optimizes the mass distribution and reduces weight compared to flat or simple conical bottoms, while the profile is optimized for structural efficiency.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP2321543B1Coupling bolt, tool machine and method for producing a coupling bolt
Publication Date: 2012.10.31 ROBERT BOSCH GMBH
  • EP2321543B1 patent drawingFigure 1~2
  • EP2321543B1 patent drawingFigure 3a~3c
  • EP2321543B1 patent drawingFigure 4

AI summary

The invention relates to a coupling bolt (50, 150) of a displaceable articulation device, in particular a drive articulation of a piston unit (32), comprising a longitudinal extension (57, 157) and a receiving bore (74, 174) extending essentially in a transversal manner in relation to said longitudinal extension (57, 157) for receiving a coupling element (28) of the articulation device. According to the invention, the coupling bolt (150) comprises at least in a front side (160, 161), a recess (154, 155) which extends along the longitudinal extension (157) and which is defined by a concave base (178, 179) when seen from the front side (160, 161).