Tire Retread Envelope Leak Testing with Vacuum Slope Control

Solution Overview

Problem

Existing methods for retreading tires lack effective leak testing during the curing process, which can affect the integrity and durability of the tire assembly.

Innovation Solution

An air evacuation system with pneumatic control logic and multiple timing cycles is used to test for leaks in the envelope surrounding the tire assembly by comparing the slope of vacuum over time to a predetermined value, activating indicators for leaks, and enabling further depressurization only when the envelope is properly sealed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the envelope is depressurized during the curing process, then compressive forces are applied to bond the tire tread to the casing, but leak testing capability is compromised without proper detection systems

Engineering Contradiction:

Improvebond strength between tire tread and casingVSAvoidenvelope seal integrity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The system performs leak testing before proceeding with the curing process by monitoring vacuum levels and slopes during an initial evacuation phase. This preliminary detection ensures the envelope is properly sealed before the actual bonding operation begins, preventing wasted curing cycles on defective assemblies.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors vacuum pressure levels and calculates the slope of pressure change over time. When the slope exceeds a predetermined threshold indicating a potential leak, the system provides feedback to prevent further depressurization or to alert operators, enabling real-time quality control during the curing process.

Inventive Principle:

Principle #23Feedback

2Extent of automation

If traditional leak testing methods are used, then simple detection is possible, but timing control and automated decision-making for proceeding with curing are insufficient

Engineering Contradiction:

Improveautomated leak testing controlVSAvoidpneumatic control logic system

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The system automatically determines whether to proceed with curing based on real-time vacuum slope analysis without requiring manual intervention. The controller self-evaluates the leak test results by comparing measured slopes against predetermined thresholds and automatically makes the decision to either proceed or abort the curing process, reducing operator workload and ensuring consistent quality decisions.

Inventive Principle:

Principle #25Self-service

3Strength

If the envelope is fully depressurized to achieve strong bonding, then tire tread adhesion is improved, but undetected leaks can compromise the entire curing process

Engineering Contradiction:

Improvetire tread adhesion to casingVSAvoidundetected leaks during curing

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The system performs leak testing before proceeding with the curing process by monitoring vacuum levels and slopes during an initial evacuation phase. This preliminary detection ensures the envelope is properly sealed before the actual bonding operation begins, preventing wasted curing cycles on defective assemblies.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors vacuum pressure levels and calculates the slope of pressure change over time. When the slope exceeds a predetermined threshold indicating a potential leak, the system provides feedback to prevent further depressurization or to alert operators, enabling real-time quality control during the curing process.

Inventive Principle:

Principle #23Feedback

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

Ensures the envelope is properly sealed, enhancing the bond between the tire tread and casing, thereby improving the quality and longevity of the retreaded tire.

Implementation Method 1

The envelope provides a seal around the tire casing and tire tread and may be connected to a vacuum that depressurizes the interior of the envelope during at least a portion of the curing process, which applies compressive forces to the tire tread against the tire casing.

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

the vacuum system may include a Venturi vacuum system

Methodology Applied

Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentEP3601986B1Method and system for leak testing enclosures

Publication Date: 2025.08.27 BRIDGESTONE BANDAG LLC

Figure 1
Figure 2~3

AI summary

A system for leak testing an envelope for a tire assembly can include a rim, an envelope sized to accommodate a green tire assembly and secured to the rim, a vacuum system in fluid communication with the envelope, and a controller. The controller can be configured to pressurize the envelope to a predetermined pressure, compare a slope of pressure over time to a predetermined value, and enable proceeding with a depressurization of the envelope responsive to determining the slope of the pressure over time being more than or equal to the predetermined value.