Replaceable Helical Screw Unit for Low-Maintenance Worm Shafts
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Solution Overview
Problem
Existing screw presses for dewatering digestate in anaerobic digestion face significant maintenance challenges due to rapid wear of spiral elements, requiring extensive welding or replacement of the entire worm shaft, which is labor-intensive and costly.
Innovation Solution
A helical screw conveyor unit designed for radial interchangeability, allowing quick and easy replacement on a worm shaft without disassembly, using fastening elements like cylinder head screws or snap connections to secure spiral elements, ensuring minimal maintenance effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If spiral elements are firmly connected to the worm shaft by welding, then the connection strength is improved, but the maintenance complexity and time increase significantly when wear occurs
Solution Approach 1:
The spiral element is divided into a modular structure consisting of a base body and a separately replaceable working surface. The working surface can be detached and replaced independently when worn, while the base body remains on the shaft. This segmentation allows maintenance without replacing the entire spiral element or performing extensive welding work.
Solution Approach 2:
The worn working surface is discarded and replaced with a new one, while the base body is recovered and retained on the shaft. This approach eliminates the need to discard or remove the entire spiral element, reducing maintenance time and complexity while maintaining connection strength through the retained base body.
2Reliability
If the entire worm shaft is replaced when spiral elements wear out, then reliability is improved, but loss of time and maintenance costs increase
Solution Approach 1:
The worm shaft system is segmented into the shaft, the base body, and the working surface. Only the worn working surface needs replacement, not the entire shaft or base body. This segmentation enables localized maintenance that restores reliability without the time loss associated with complete shaft replacement.
Solution Approach 2:
The worn working surface is extracted and removed from the base body, allowing replacement of only the degraded component. This extraction principle enables maintenance personnel to replace the working surface independently without removing the entire worm shaft from its mounting, significantly reducing maintenance time while ensuring operational reliability.
3Ease of repair
If radial interchangeability is implemented for spiral elements, then ease of repair is improved, but device complexity increases due to additional fastening mechanisms
Solution Approach 1:
The fastening mechanism is implemented locally at the interface between the working surface and base body, rather than throughout the entire spiral element or shaft. This localized fastening system provides radial interchangeability where needed while maintaining simplicity in the rest of the structure, balancing ease of repair with acceptable device complexity.
Data Source
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AI summary
In order to develop a helical screw conveyor unit (100) in such a way that the helical screw conveyor unit (100) can be maintained with little maintenance outlay, said helical screw conveyor unit being designed as an exchangeable element for a helix (240), wound in a screw-like or spiral-like manner, of a screw shaft (200) of a screw extruder and comprising a main body (10) having a helical element (30) wound in a screw-like manner, according to the invention: - the upper side (16) of the lateral face is concavely bent like a shell about the longitudinal axis (L) and the main body (10) comprises a radial opening (20) through which a fastening region (40) of a shaft (230) of the screw shaft (200) is intended to be guided; - the helical element (30) has at most a half helix rotation; - the lateral face of the main body (10) has an inner face (18) designed to rest against the fastening region (40); and - the helical screw conveyor unit (100) comprises at least one fastening element (34) designed to releasably fasten the main body (10) to the fastening region (40).