Pneumatic Tire Shaping via Stepwise Pressure Profile
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Solution Overview
Problem
In the manufacturing of radial tires, the radial expansion of the green case is minimal due to orthogonal carcass cord arrangement, leading to increased irregularities in cord openings and unevenness on the tire surface, which compromises the uniformity of the tire.
Innovation Solution
A method involving a stepwise pressure profile for fluid supply during the shaping of the green tire, where the initial stage pressure is lower than the final stage pressure, allowing the green case to expand from 8% to 40% of its full expansion amount, ensuring uniform expansion and minimizing irregularities in cord openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the green case is expanded using a single high pressure throughout the shaping process, then the shaping speed and productivity are improved, but the irregularities in cord openings between carcass cords increase and uniformity of the tire deteriorates
Solution Approach 1:
The shaping process is divided into multiple stages with different pressure levels. The first stage uses a lower pressure (first pressure) to expand the green case to an intermediate state, and the second stage uses a higher pressure (second pressure) to complete the expansion to the final shape. This segmentation allows the carcass cords to be gradually separated without creating excessive irregularities, while still maintaining efficient production speed.
Solution Approach 2:
The first pressure is applied preliminarily to expand the green case to an intermediate expansion state before the final high-pressure expansion. This preliminary action creates initial space between the closely arranged carcass cords in radial tires, preparing the structure for the subsequent final expansion without causing sudden cord separation and irregularities.
2Loss of time
If the green case is expanded rapidly to full size, then the manufacturing time is reduced, but the irregularities in cord openings increase and tire surface evenness deteriorates
Solution Approach 1:
The expansion process is segmented into two distinct pressure stages. The first stage expands the green case to an intermediate state with controlled cord separation, and the second stage completes the expansion to full size. This segmentation reduces the total time compared to a single slow expansion while preventing excessive cord opening irregularities that would occur with rapid single-stage expansion.
Solution Approach 2:
The pressure parameter is changed in two steps during the expansion process. The first pressure is set to a lower value to allow gradual cord separation, and the second pressure is increased to complete the expansion. This parameter change strategy optimizes both time efficiency and surface evenness by controlling the rate of cord separation at different expansion phases.
3Manufacturing precision
If a lower pressure is used throughout the shaping process, then the uniformity of cord openings is improved, but the productivity and manufacturing efficiency decrease
Solution Approach 1:
The process uses a lower first pressure for the initial expansion phase to ensure uniform cord opening, then transitions to a higher second pressure for the final expansion phase. This segmentation allows the process to benefit from both low-pressure uniformity and high-pressure efficiency, achieving good cord opening uniformity without sacrificing overall manufacturing speed.
Solution Approach 2:
The lower first pressure is used preliminarily to establish uniform cord separation patterns. Once this uniform structure is established, the higher second pressure can be applied to complete the expansion rapidly without disrupting the uniform cord opening pattern, thus maintaining both uniformity and productivity.
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 enhances the uniformity of the tire by suppressing irregularities in cord openings, resulting in a more even tire surface and improved manufacturing consistency.
Implementation Method 1
shaping a green tire by expanding the green case into a toroidal shape with the supply of a fluid into the green case
Data Source
AI summary
A method of manufacturing a pneumatic tire including forming a green case by cylindrically winding a tire component member which includes at least one layer of a carcass ply. The green tire is shaped by expanding the green case into a toroidal shape with the supply of a fluid into the green case so that the green case adheres to a tread ring arranged radially outside the green case. The green tire is subjected to vulcanization molding within a mold die. During the shaping of the green tire, the fluid is supplied in accordance with a pressure profile which changes in a stepwise manner. The pressure profile is set such that a former stage pressure which allows the green case to expand to 35% to 40% of a full expansion amount is set lower than a final stage pressure in a final stage.