Air-Permeable Mandrels for Elastomer Hollow Body Vulcanization

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Solution Overview

Problem

The existing methods for producing shaped hollow bodies using vulcanization devices are limited by the number of parts that can be produced per process due to the internal pressure requirements, which restricts output.

Innovation Solution

The method involves using mandrels with air-permeable and airtight segments, pressurizing air chambers, and adjustable pressure compensation elements to balance process forces and facilitate multiple simultaneous vulcanization processes, allowing for easier removal of hollow bodies by forming an air cushion between the mandrels and the finished parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a vulcanization press is used to produce hollow bodies, then the parts can be vulcanized by applying compressed air, but the number of parts that can be produced simultaneously is limited by the clamping force of the press

Engineering Contradiction:
Improvenumber of parts produced per processVSAvoidclamping force requirement
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The patent replaces the mechanical clamping system with a pneumatic system. Instead of using a vulcanization press with clamping force to hold multiple parts, the invention uses air-permeable mandrels that are pressurized with compressed air. This pneumatic pressure holds the blanks against the mandrels and maintains the necessary force throughout the vulcanization process, allowing many more parts to be produced simultaneously without requiring excessive mechanical clamping force.

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

Solution Approach 2:

The patent applies pneumatic principles by introducing compressed air into the mandrels through air-permeable wall areas. The air pressure inside the mandrels creates a holding force that presses the vulcanized hollow bodies against the mandrel surface. This pneumatic holding mechanism replaces the need for mechanical clamping and enables high-volume simultaneous production, as the air pressure can be distributed across numerous mandrels at once.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Productivity

If air-permeable mandrels are used to enable multiple simultaneous vulcanization processes, then productivity increases, but process control becomes more complex due to air flow coordination

Engineering Contradiction:
Improvenumber of parts produced per processVSAvoidair flow coordination system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the mandrel into segments with different air permeability characteristics. Some wall areas are air-permeable to allow air flow for holding and removal, while other areas are airtight to maintain structural integrity and control pressure distribution. This segmentation allows independent control of air flow in different regions, simplifying the overall coordination of air flow across multiple mandrels while maintaining high productivity.

Inventive Principle:
Principle #1Segmentation

3Productivity

If compressed air is used to hold blanks against mandrels during vulcanization, then multiple parts can be produced simultaneously, but air may become trapped between mandrel and blank causing defects

Engineering Contradiction:
Improvenumber of parts produced per processVSAvoidsurface quality of hollow bodies
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses air-permeable mandrel wall areas made from porous or air-permeable materials that allow controlled air flow. These materials enable air to pass through the mandrel wall during the vulcanization process, preventing air pockets from forming between the mandrel and the blank. The controlled permeability ensures uniform air distribution and eliminates surface defects while maintaining the productivity benefits of simultaneous multi-part production.

Inventive Principle:
Principle #31Porous materials

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 approach enables the production of multiple hollow bodies at once, optimizing process parameters and improving output by balancing pressure and air flow, while ensuring easy removal from the mandrels.

Implementation Method 1

pressurizing the air chambers of the mandrels, thereby allowing air to pass through the air-permeable wall areas from the air chambers between the mandrels and the finished vulcanized hollow bodies, thereby forming an air cushion between the mandrels and the hollow bodies

Methodology Applied
Scientific EffectAir cushion: Air Lubrication

Implementation Method 2

air trapped between the mandrel and the wall of the blank when it is placed on the mandrel can be forced into the corresponding air chambers of the mandrel when the autoclave is pressurized

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP3727780B1Method for producing a molded hollow body, and device for carrying out the method
Publication Date: 2023.09.06 CONTITECH MGW GMBH
  • EP3727780B1 patent drawingFigure 1
  • EP3727780B1 patent drawingFigure 2
  • EP3727780B1 patent drawingFigure 3

AI summary

The invention relates to a method for producing a molded hollow body made of an elastomer material (8). The aim of the invention is to provide a method for producing the aforementioned hollow bodies (8), said method allowing a higher output. This is achieved in that the method has at least the following steps, namely: a) pushing a prefabricated blank (5) onto a respective mandrel (1), wherein the mandrel (1) has at least one region with a wall (2) which is designed to be permeable to air, and each mandrel (1) has at least one air chamber (3) which is operatively connected to the at least one region of the air-permeable wall (2, 2A), b) introducing the mandrels (1) with plugged-on blanks (5) into a known autoclave, c1) applying pressure and heat to the autoclave, wherein air (6) which is enclosed between the blanks (5) and the mandrels (1) is pressed through the regions of an air-tight wall (2, 2A) into the respective air chamber (3), in the process vulcanizing the blanks (5), d) relieving and cooling the autoclave, e) removing the mandrels (1) with completely vulcanized and molded hollow bodies (8), and f2) detaching the hollow bodies (8) from the mandrels (1). The mandrels (1) are composed of at least one segment (2B) of an air-tight wall and at least one segment (2A) of an air-permeable wall in a specified sequence in the axial direction.