Plastic Shaft Pipe Mechanical Interlocking Assembly
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Solution Overview
Problem
Existing shaft arrangements in drainage technology face challenges with assembly flexibility, high transport costs, and material fatigue due to the need for pre-assembled units and complex fastening methods that require thermal processes or additional locking devices, which limit production and logistics flexibility and increase costs.
Innovation Solution
A shaft arrangement featuring a shaft cover frame with a tubular insertion section and a plastic shaft pipe, where at least one retaining projection is plastically deformed to create a depression in the shaft pipe, forming a strong, play-free connection without additional holding means, allowing for location-independent assembly and simplified production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal shrinking method is used to attach shaft pipe to shaft cover frame, then connection strength is improved, but assembly flexibility deteriorates and transport costs increase
Solution Approach 1:
The patent replaces the thermal shrinking process with a mechanical interlocking system consisting of an expansion element and corresponding locking elements. The expansion element is inserted into the shaft pipe and expanded mechanically (e.g., using a expansion tool or by leveraging the shaft cover frame weight) to engage with locking elements inside the pipe, achieving strong connection without thermal processing.
Solution Approach 2:
The connection system is designed to be self-assembling on-site. The expansion element and locking elements work together automatically once inserted, requiring no external thermal processing equipment or specialized factory equipment. The system uses the weight of the shaft cover frame or simple mechanical tools to complete the connection.
2Strength
If shaft pipe and shaft cover frame are pre-assembled as unit, then connection strength is improved, but transport costs and logistics complexity increase
Solution Approach 1:
The patent divides the shaft arrangement into separate modular components: the shaft cover frame and the shaft pipe can be manufactured and transported independently. The connection elements (expansion element and locking elements) are integrated into one of these components, allowing them to be assembled on-site without requiring pre-assembly of the entire unit.
3Reliability
If additional locking devices are added to shaft pipe, then connection reliability is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent combines multiple functions into the expansion element: it serves as both the connection carrier and the locking mechanism. The expansion element integrates the expansion body and locking elements (such as ribs, protrusions, or interlocking features) into a single component that works with the shaft cover frame to achieve reliable connection without requiring separate locking devices.
4Adaptability or versatility
If inwardly projecting fastening elements are used on shaft pipe, then assembly flexibility is improved, but service life deteriorates due to material fatigue
Solution Approach 1:
Instead of projecting fastening elements inward from the shaft pipe (which concentrates stress on the plastic pipe material), the patent inverts the approach by using an expansion element that engages with locking elements positioned inside the pipe. The locking elements are designed to distribute forces evenly along the engagement surface, preventing stress concentration and material fatigue in the shaft pipe.
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 solution enables a robust, play-free connection that withstands vibrations and loads, simplifies assembly, reduces production and transport costs, and extends the service life of the shaft arrangement by eliminating the need for pre-processing and exact angular alignment.
Implementation Method 1
at least one retaining projection (26, 27) which is positively connected to the shaft pipe (10) by plastically deforming the shaft pipe (10)
Data Source
Figure 1~2
Figure 3
AI summary
The arrangement (1) has a shaft pipe (10) made of plastic, and a shaft covering frame (20) comprising a tubular insertion section, which is inserted into a pipe aperture (11) of the shaft pipe. A retaining projection (26) is arranged at the insertion section and connected with the shaft pipe in a mounted state by plastic deformation of the shaft pipe in a form-fit manner. The retaining projection comprises an accumulating surface (30) turned to a free end of the insertion section and running in a flat angle to the insertion section. An independent claim is also included for a method for manufacturing a shaft arrangement.