Composite Rotary Tool Structure for Stable Large-Bore Machining
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Solution Overview
Problem
Machining large inner diameters, such as those in electric motor stator housings, requires tools that are dimensionally stable, easy to handle, and cost-effective, while maintaining high mechanical resilience and precision, as conventional tools face challenges with weight-related accuracy issues and thermal expansion.
Innovation Solution
A rotary tool with a fiber-plastic composite support structure having a low coefficient of thermal expansion, designed with an umbrella-like expansion and a tension/compression strut framework for reduced weight and enhanced stiffness, allowing for precise machining and integration of a stiffening structure without significant weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional materials are used for the support structure, then mechanical strength is sufficient, but the tool weight increases causing dimensional accuracy degradation and handling difficulties
Solution Approach 1:
The support structure is made from fiber-reinforced plastic composite material combining glass fibers or carbon fibers with a thermoplastic matrix. This composite material provides high mechanical strength and stiffness while maintaining low density, achieving both weight reduction and dimensional accuracy requirements simultaneously
Solution Approach 2:
The patent specifies precise material parameters including density between 1.5-2.5 g/cm³, tensile strength ≥50 MPa, and最关键地, coefficient of thermal expansion ≤5 ppm/K in radial direction. These parameter constraints ensure the material delivers both lightweight properties and dimensional stability during machining operations
2Stability of the object's composition
If the support structure is made heavier to increase stiffness, then dimensional stability improves, but the tilting moment increases reducing handling stability
Solution Approach 1:
The fiber-reinforced plastic composite provides high specific stiffness (stiffness-to-weight ratio). The fiber orientation and distribution are optimized to provide radial stiffness for dimensional stability while keeping the overall structure lightweight for stable handling by automatic tool changers
Solution Approach 2:
The patent specifies a coefficient of thermal expansion of ≤5 ppm/K in the radial direction, which is 10-100 times lower than conventional metals. This parameter ensures minimal thermal deformation during machining, maintaining dimensional stability without requiring increased mass that would worsen handling stability
3Ease of operation
If the tool mass is reduced for better handling, then tilting moment decreases improving stability, but mechanical strength may be compromised
Solution Approach 1:
The fiber-reinforced plastic composite material achieves high strength-to-weight ratio. The embedded glass or carbon fibers provide tensile strength ≥50 MPa while the thermoplastic matrix provides ductility and toughness, delivering both lightweight properties and sufficient mechanical strength for machining large internal diameters
Solution Approach 2:
The patent specifies density between 1.5-2.5 g/cm³ which is significantly lower than conventional metals like steel (7.8 g/cm³) or titanium (4.5 g/cm³). This parameter reduction directly decreases tool mass and tilting moment while the composite structure maintains mechanical strength through fiber reinforcement
4Manufacturing precision
If conventional materials with high thermal expansion are used, then material availability and cost are favorable, but cutting edge position changes under thermal stress reducing machining precision
Solution Approach 1:
The fiber-reinforced plastic composite with thermoplastic matrix provides inherently low thermal expansion. The fiber reinforcement constrains thermal deformation of the matrix, achieving radial thermal expansion ≤5 ppm/K. This eliminates the need for expensive thermal compensation systems while maintaining material availability through established composite manufacturing processes
Solution Approach 2:
The patent specifies coefficient of thermal expansion ≤5 ppm/K in radial direction, which is dramatically lower than conventional metals (e.g., aluminum 23 ppm/K, steel 12 ppm/K). This parameter ensures cutting edge position remains stable under thermal stress from machining operations, maintaining precision without sacrificing manufacturability
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 rotary tool ensures high dimensional accuracy and mechanical resilience, reduces weight-related handling issues, and maintains precision under thermal stress, enabling efficient machining of large diameters with existing spindle systems.
Implementation Method 1
the fiber-reinforced plastic composite has a coefficient of thermal expansion of less than 5 ppm/K (5E-6 1/K), preferably less than 2 ppm/K, and particularly preferably less than 1 ppm/K, in at least one direction transverse to the axis of rotation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a rotary tool (1; 101; 201) for machining large internal diameters, on the outer circumference (2) of which at least one cutting edge (4) is arranged, with a support structure (10; 110; 210) which directly or indirectly supports the at least one cutting edge (4), and with a clamping section (24) for coupling to a tool holder, wherein the support structure (10; 110; 210) is made of a fiber-reinforced plastic composite with a matrix system with embedded fibers, and the fiber-reinforced plastic composite has a coefficient of thermal expansion of less than 5 ppm/K (5E-6 1/K), preferably less than 2 ppm/K, and particularly preferably less than 1 ppm/K, in at least one direction transverse to the axis of rotation (A).