PVC-O Pipe Belling Machine for Precise Bell Socket Formation

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Solution Overview

Problem

Existing belling machines for PVC-O pipes struggle to consistently form precise bell sockets due to the variability in pipe wall thickness and thermal state, leading to irregular contraction and difficulty in achieving a repeatable, hermetic seal, especially for pipes intended for operating pressures greater than 16 Bar.

Innovation Solution

A belling machine with a specially configured shaping flange that performs a single actuating action to control the formation of the bell socket, ensuring precise adherence of the pipe wall to the mandrel, and incorporates an electromechanical device to accurately position the mandrel and flange for consistent shaping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional belling machines are used for PVC-O pipes, then the belling process can be performed, but the pipe wall thickness variability and thermal state irregularities lead to inconsistent bell socket formation and difficulty in achieving hermetic seal

Engineering Contradiction:
Improvebell socket formation precisionVSAvoidhermetic seal reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The heating station heats the pipe end to a predetermined temperature range (80-105°C) before the belling operation, and the mandrel is pre-positioned with electromechanical actuators. This preliminary preparation ensures the pipe material is in the optimal rheological state for forming, compensating for thickness variability and thermal irregularities before the actual belling process begins.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system incorporates sensors that detect the pipe's thermal state and dimensions, feeding this information back to the control system. The control system adjusts heating parameters and mandrel positioning based on this feedback, ensuring consistent bell socket formation despite variations in pipe wall thickness and thermal conditions.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If a simple mandrel system is used, then the device complexity is low, but the shaping precision and consistency of bell socket formation are insufficient

Engineering Contradiction:
Improvebell socket shape precisionVSAvoidbelling machine complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mandrel system is made dynamic through electromechanical actuators that can precisely control the mandrel's position, insertion depth, and withdrawal timing. This dynamic control allows the mandrel to adapt to variations in pipe dimensions and thermal state, achieving high shaping precision without requiring an overly complex mechanical structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Traditional purely mechanical positioning and control systems are replaced with electromechanical actuators and electronic control. This substitution provides more precise and repeatable positioning while maintaining reasonable device complexity, as electronic control offers finer adjustment capabilities compared to mechanical linkages.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If multiple actuating actions are used for shaping, then the shaping completeness can be improved, but the process complexity and time consumption increase

Engineering Contradiction:
Improvebell socket formation completenessVSAvoidbelling process efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Multiple shaping functions are merged into a single integrated mandrel assembly that performs heating, positioning, shaping, and cooling operations in one continuous motion. The electromechanical actuator coordinates these functions simultaneously, achieving complete bell socket formation in a single actuating cycle rather than through multiple separate operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The belling process is designed as a continuous operation where the mandrel remains engaged with the pipe throughout the forming process, applying shaping force continuously as the pipe material transitions through its rheological state. This continuous action eliminates idle time between operations and maintains optimal forming conditions throughout the process.

Inventive Principle:
Principle #20Continuity of useful action

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 the production of PVC-O pipes with integral bell sockets that meet functional conformity requirements, ensuring a hermetic seal and reliable gasket retention, even for pipes with larger wall thicknesses and higher operating pressures.

Implementation Method 1

the cut pipe from the extrusion line is softened at one end in one or more heating stations. Thus, in a thermal state greater than that of the glassy transition temperature

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 2

The action which forms the bell socket against the shaping tool is the spontaneous contraction of the oriented molecules

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP4644091A1Machine and method for belling PVC-o pipes
Publication Date: 2025.11.05 SICA SPA
  • EP4644091A1 patent drawingFigure 1~1b
  • EP4644091A1 patent drawingFigure 2~2b
  • EP4644091A1 patent drawingFigure 3

AI summary

A belling machine comprising a forming station (600), the PVC-O pipes (1) each have an integral bell socket (3) formed on it and provided with a seat (6) for receiving a gasket (100); the forming station (600) comprises a belling apparatus (40) for belling the end of the PVC-O pipe (1a) to be processed; the apparatus (40) comprises forming means (59) for forming the end of the pipe (1a) into a bell socket and which comprise a mechanical mandrel (15), intended to be inserted into one end of the pipe (1a) and a shaping flange (14) for shaping at least part of the end of the pipe (1a); the shaping flange (14) comprises an annular body (26) whose inside surface (27) defines, with the outside surface (36) of the mandrel (15), a shaping chamber (35) for shaping a portion of the bell socket (3a) being formed.