Injection-Molded Composite Rotor Blade for Turbomolecular Pumps
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Solution Overview
Problem
Existing turbomolecular pump rotor blades are difficult and expensive to manufacture with complex geometries, limiting their pumping performance and increasing production costs.
Innovation Solution
A rotor blade design featuring a polymer material reinforced with short fibers, utilizing a continuous blade twist and taper, allowing for injection molding of complex geometries that enhance strength and aerodynamics, reducing weight and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotor blades are manufactured from aluminium alloys with complex geometries, then pumping performance is improved, but manufacturing difficulty and cost increase prohibitively
Solution Approach 1:
The patent uses polymer composite materials (polyamide 6, polyphthalamide, polyimide, or polyether ether ketone) instead of traditional aluminium alloys. These polymers can be injection molded into complex geometries much more easily than metal machining, while maintaining the strength and lightweight properties needed for high-speed rotor operation at 10,000-100,000 rpm
Solution Approach 2:
The patent changes the material parameters from metal to polymer composite, enabling a complete transformation of the manufacturing process from difficult metal forming to easy injection molding. This allows complex blade geometries to be produced cost-effectively while maintaining the required mechanical properties for vacuum pump operation
2Strength
If rotor blades are manufactured from aluminium alloys, then strength and low weight are achieved, but complex blade geometries become prohibitively difficult and expensive to produce
Solution Approach 1:
The patent employs reinforced polymer composites that provide high strength-to-weight ratio comparable to aluminum alloys, but with the added benefit of being formable into complex geometries through injection molding. The polymer matrix combined with reinforcing fibers achieves the necessary mechanical strength for high-speed rotation while enabling complex blade shapes
Solution Approach 2:
The patent applies different material properties to different parts of the rotor blade by using injection molding techniques that can vary material distribution, fiber orientation, and thickness locally. This allows optimization of strength where needed while maintaining complex overall geometries that would be difficult to achieve with uniform metal construction
3Ease of manufacture
If simpler rotor blade geometries are used, then manufacturing is easier and more cost-effective, but pumping performance is limited
Solution Approach 1:
The use of injection-moldable polymer composites removes the manufacturing penalty for complex geometries, allowing the optimization of blade shape for maximum pumping performance. Complex features such as variable thickness, curved surfaces, and optimized airfoil sections can be built directly into the mold without additional machining or assembly steps
Solution Approach 2:
The patent transitions from two-dimensional simple blade shapes to three-dimensional complex geometries enabled by injection molding. The polymer material allows creation of varied thickness profiles, curved surfaces, and intricate cross-sections that optimize gas molecule interaction and pumping efficiency while being manufactured as single integrated parts
Data Source
AI summary
The present disclosure relates to a rotor blade for a turbomolecular vacuum pump. The rotor blade has a blade angle of 0° at the root, which increases continuously along substantially the entire span of the rotor blade. The rotor blade tapers from a maximum thickness at the root to a point of minimum thickness over a portion of its span, and is made of a polymer material reinforced with short fibres. This provides a rotor blade with a more complex geometry that has reduced weight and improved performance and cost-effectiveness. The present disclosure also relates to a rotor comprising the rotor blade, a mould for injection moulding the rotor blade or rotor, and a method of injection moulding the rotor blade or rotor.