Magnesium Racket Frame with Variable Wall Thickness

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Solution Overview

Problem

Existing methods for manufacturing ball game racket frames struggle to optimize rigidity and weight distribution due to limitations in varying wall thickness, particularly with the tubular blow molding process and constant cross-section aluminum profiles.

Innovation Solution

The use of magnesium injection molding techniques, specifically the thixoprocess, allows for targeted variation of wall thickness along both cross-sectional and longitudinal sections of a hollow magnesium frame profile, enabling optimal rigidity and weight distribution by designing the injection mold to achieve varying wall thicknesses, including thin sections and localized reinforcement with materials like carbon and fiberglass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the frame is manufactured using the tubular blow molding process with prepreg layers, then the frame can be produced with standardized cross-sectional shapes, but the wall thickness cannot be varied in a targeted manner along the cross section to optimize local rigidity and weight distribution

Engineering Contradiction:
Improvewall thickness variationVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by transitioning from the tubular blow molding process to magnesium injection molding, which enables precise control of wall thickness as a variable parameter. The injection molding process allows the wall thickness to be adjusted independently at different locations along the frame cross-section through mold design, achieving targeted variation to optimize local rigidity and weight distribution while maintaining manufacturing efficiency.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If aluminum profiles with constant cross-section are used to bend the frame, then the manufacturing process is simple, but the wall thickness remains constant and cannot be optimized for local rigidity requirements

Engineering Contradiction:
Improvewall thickness controlVSAvoidframe structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements local quality by enabling different wall thicknesses at different locations of the frame cross-section. The injection molding process allows the mold cavity design to specify varying wall thicknesses in different areas, so that regions requiring higher rigidity (such as the head and throat areas) can have thicker walls, while less critical areas have thinner walls to reduce weight. This localized optimization of wall thickness directly addresses the limitation of constant cross-section aluminum profiles.

Inventive Principle:
Principle #3Local quality

3Strength

If a solid metal magnesium frame is used, then the frame has high strength, but the weight is excessive and does not meet modern racket requirements

Engineering Contradiction:
Improveframe strengthVSAvoidracket weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies the principle of flexible shells and thin films by using a hollow magnesium frame structure instead of a solid one. The injection molding process creates a hollow profile with controlled wall thickness, forming a shell-like structure that provides high strength-to-weight ratio. The hollow design significantly reduces the amount of magnesium material required, thereby reducing the overall frame weight, while the optimized wall thickness distribution maintains the necessary strength and rigidity through strategic thickening in critical areas.

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If the wall thickness is varied significantly along the frame contour, then the local rigidity and weight distribution are optimized, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveframe performanceVSAvoidinjection molding complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by incorporating all wall thickness variations directly into the injection mold cavity design before the manufacturing process begins. The mold is pre-configured with the specific wall thickness profile required for optimal frame performance, eliminating the need for post-manufacturing adjustments or complex assembly operations. This preliminary integration of design requirements into the tooling itself simplifies the actual manufacturing process while achieving the desired variable wall thickness distribution for optimized rigidity and weight.

Inventive Principle:
Principle #10Preliminary action

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 approach results in a frame that can achieve significant variations in wall thickness, optimizing stiffness and strength while minimizing weight, with automated production and reduced manual processing, allowing for precise control over the frame's structure and improved playability.

Implementation Method 1

the frame is made using magnesium injection molding techniques according to the so-called thixoprocess

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

the so-called fusible core technique, in which an injection mold core is melted after the frame has been shaped

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3016721B1Racket or club consisting of magnesium
Publication Date: 2019.09.11 HEAD TECHNOLOGY GMBH
  • EP3016721B1 patent drawingFigure 1~2
  • EP3016721B1 patent drawingFigure 3~4
  • EP3016721B1 patent drawingFigure 5~6

AI summary

The present invention relates to a frame for a ball-game racket comprising a head portion and a handle portion, wherein the frame is configured as a hollow profile and comprises magnesium and wherein the wall thickness of the hollow profile varies along a cross-section through the hollow frame profile, as well as to a process for producing such a racket.