Fiber-Reinforced Polymer Screw Rotor for Near-Net-Shape Manufacturing

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Solution Overview

Problem

Conventional screw rotors made of cast iron or steel require labor-intensive finishing processes to achieve fine tolerances, leading to increased costs, material waste, and weight, while existing polymer-based solutions do not adequately address these issues.

Innovation Solution

A screw rotor made of polymer reinforced with fibers, manufactured through injection molding, which approximates the final shape closely, reducing the need for extensive finishing and allowing for easier production with less material loss and improved mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If cast iron or steel is used for screw rotor manufacturing, then strength and durability are improved, but weight increases and material waste occurs during finishing

Engineering Contradiction:
ImprovestrengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs fiber-reinforced polymer composite materials (specifically glass fiber, carbon fiber, or aramid fiber reinforced plastics) to manufacture the screw rotor. This composite material approach provides sufficient mechanical strength and durability while significantly reducing the weight compared to traditional cast iron or steel rotors, directly resolving the contradiction between strength and weight

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If conventional casting and finishing processes are used, then manufacturing precision is achieved, but production time and labor costs increase significantly

Engineering Contradiction:
Improvefinishing precisionVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The invention uses injection molding technology to pre-form the screw rotor with highly accurate dimensional precision during the molding process itself. The mold cavity is designed to directly produce the final rotor geometry with tolerances of IT8-IT10 grade, eliminating the need for subsequent time-consuming finishing operations such as grinding, filing, and milling that traditionally consumed 70-80% of production time

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If traditional cutting operations are performed to achieve fine tolerances, then manufacturing precision is improved, but material waste increases

Engineering Contradiction:
Improvetolerance precisionVSAvoidmaterial waste
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The injection molding process is designed to directly produce the screw rotor at or very near final dimensions, with the mold cavity precisely engineered to create the required screw profile and tolerances (IT8-IT10) during forming. This preliminary precision action eliminates the need for material-removing finishing operations, thereby preventing material waste while achieving the required manufacturing precision

Inventive Principle:
Principle #10Preliminary action

4Manufacturing precision

If extensive finishing processes are applied, then manufacturing precision is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvesurface finish qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the complex multi-step finishing processes (grinding, filing, milling, scraping) from the manufacturing workflow. By achieving the required surface finish quality and dimensional precision directly through optimized injection molding with properly designed mold cavities and fiber orientation control, the patent removes these cumbersome intermediate operations, thereby reducing manufacturing process complexity while maintaining high precision standards

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3924626B1Screw rotor
Publication Date: 2025.09.10 ATLAS COPCO AIRPOWER NV
  • EP3924626B1 patent drawingFigure 1~2
  • EP3924626B1 patent drawingFigure 3~4
  • EP3924626B1 patent drawingFigure 5~7

AI summary

Screw rotor, characterized in that the screw rotor (1) is made out of polymer, wherein the screw rotor (1) consists of a shaft (2) with a rotor body (3) on it, wherein the polymer of the shaft (2) is reinforced with fibers (4), wherein the shaft (2) features elements (5a, 5b) that engage the rotor body (3) or corresponding elements (5c) on the rotor body (3), such that the elements (5a, 5b, 5c) prevent an axial and/or rotational movement of the shaft (2) with respect to the rotor body (3),