Plastic Shaft Pipe Elliptical Clamping for Drainage Assembly
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Solution Overview
Problem
Current shaft arrangements in drainage technology, particularly those using plastic manholes and cast-iron frames, face challenges in on-site assembly and material fatigue due to non-optimal fastening methods, leading to high logistics costs and reduced service life.
Innovation Solution
A clamping mechanism with an elliptical frame apron or thickened areas on the manhole frame ensures secure engagement and even stress distribution, allowing independent manufacturing and on-site assembly of the shaft pipe and frame, enhancing service life by increasing friction and distributing stresses homogeneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plastic pipe is thermally shrunk onto the cast-iron manhole frame at the factory, then the components are connected in a non-positive manner, but the thermal process cannot be carried out on site and logistics costs increase due to transporting the complete assembly
Solution Approach 1:
The invention divides the shaft arrangement into separable components (manhole frame and shaft pipe) that can be manufactured and transported independently, then assembled on-site through a two-stage fastening process. This segmentation resolves the contradiction by enabling both reliable connection and production flexibility.
Solution Approach 2:
The invention implements preliminary action through a two-stage fastening approach: first inserting protruding fastening elements into recesses for initial positioning, then applying a bonding agent for permanent fixation. This preliminary mechanical engagement ensures proper alignment before final bonding, achieving reliable connection without requiring factory-based thermal processing.
2Ease of operation
If fastening elements protruding inwards are used to attach the shaft pipe to the manhole frame, then on-site assembly is enabled, but the force is exerted in a focused manner leading to material fatigue and reduced service life
Solution Approach 1:
The invention applies local quality by combining localized mechanical fastening (protruding elements in recesses) with distributed bonding agent application. The mechanical fasteners provide localized positioning while the bonding agent distributes stresses across the entire contact surface, preventing material fatigue and extending service life while maintaining ease of assembly.
3Productivity
If the manhole frame and pipe are delivered separately to the construction site, then logistics costs are reduced, but the fastening elements are not optimally positioned due to play between components
Solution Approach 1:
The protruding fastening elements and corresponding recesses are pre-formed during manufacturing with precise dimensional tolerances. When the manhole frame and shaft pipe are assembled on-site, these pre-formed features automatically align and engage, eliminating positioning errors that would otherwise result from play between components. This preliminary precision engineering enables both separate delivery and precise fastening.
4Reliability
If a clamping means is introduced to force the plastic pipe to assume an elliptical shape, then the pipe is secured firmly against the frame and friction is increased, but the pipe geometry is altered
Solution Approach 1:
The clamping means intentionally introduces asymmetry by forcing the circular shaft pipe to assume an elliptical shape that matches the asymmetric stress distribution and contact geometry with the manhole frame. This asymmetric deformation optimizes the contact area and friction characteristics, enhancing connection reliability while the alteration in shape is accepted as a functional adaptation.
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
This solution enables flexible on-site assembly, reduces logistics costs, and significantly extends the service life of the shaft arrangement by ensuring secure engagement and uniform stress distribution between the plastic pipe and the manhole frame.
Implementation Method 1
The clamping means according to the invention on the manhole frame forces the plastic pipe in the contact area to the manhole frame to assume an essentially elliptical shape
Implementation Method 2
In addition, the clamping device causes an increase in the coefficient of friction between the manhole frame and the pipe
Data Source
Figure 1
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Figure 3
AI summary
The arrangement (10) has a manhole frame (13) attached with a shaft pipe (11). A latching unit (20) is arranged at the shaft pipe and another latching unit (21) is arranged at the manhole frame. A tensioning unit is arranged on the manhole frame for bringing the shaft pipe in contact with the manhole frame in the region of the latch units that are designed as a detent (22) and a recess (23) and include a pocket (24). An elliptical frame apron (15) is formed on the manhole frame, and the tensioning unit is formed by the frame apron.