Rigid Core Mold Segments for Pneumatic Tire Extraction
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Solution Overview
Problem
The existing methods for manufacturing pneumatic tires using rigid core molds require significant force and time to remove the core segments due to the shape of the molding surface, which increases labor and cycle time.
Innovation Solution
A rigid core mold with a modified molding surface design, characterized by a specific ratio of widths and angles, allows for easier extraction of core segments by reducing frictional resistance, featuring a gradually decreasing width and controlled angles to facilitate inward movement in the tire radial direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the core mold is designed with a conventional molding surface shape, then the tire inner surface can be formed correctly, but a particularly large force is required to pass through the bead portions during core segment removal
Solution Approach 1:
The molding surface is designed with different geometric characteristics in different regions: the bead portion region has a specific angle range (10-45 degrees) and width ratio (Bd/W ≥ 0.60) to facilitate easy core removal, while the sidewall portion region maintains appropriate dimensions for proper tire shaping. This local differentiation allows each region to optimize for its specific function.
Solution Approach 2:
The invention changes the geometric parameters of the molding surface, specifically controlling the angle α of the tangent line in the bead portion region to be within 10-45 degrees relative to the radial direction, and setting the width ratio Bd/W to be at least 0.60. These parameter adjustments reduce the frictional resistance and enable easier core segment extraction.
2Productivity
If the conventional core mold design is used, then the tire can be manufactured, but the cycle time of the core-mold taking-out step is increased due to large removal force requirements
Solution Approach 1:
The molding surface geometry is optimized locally in the bead portion region with specific angle and width ratio parameters, creating a region that facilitates rapid core extraction. This localized optimization directly reduces the time required for the taking-out step without compromising overall tire quality.
Solution Approach 2:
The invention converts the potentially harmful large frictional resistance at the bead portions into a beneficial feature by designing the molding surface with specific geometric parameters that reduce this resistance. The controlled angle and width ratio transform the bead portion from a bottleneck into a facilitation zone for core removal.
3Strength
If the molding surface has a shape that requires large removal force, then the core segments can be securely held during vulcanization, but significant labor is required to take out the core-mold main portion
Solution Approach 1:
The molding surface is designed with different geometric characteristics for different functional requirements: the bead portion region uses specific angle and width ratio parameters to enable easy removal, while maintaining sufficient holding strength during vulcanization through appropriate dimensional control. The sidewall region maintains geometry optimized for tire shaping accuracy.
Solution Approach 2:
The core mold is divided into multiple core segments that can be removed in series. The molding surface geometry is optimized to facilitate this segmented removal process, with the bead portion design enabling each segment to be extracted sequentially with reduced force requirements.
Data Source
AI summary
A technique for easily taking out a main body of a core mold is proposed. An annular core-mold main portion 11 having a molding surface 18 for shaping an inner surface of a pneumatic tire is included, and the core-mold main portion 11 is composed of a plurality of segments each of which is taken out toward the inside in a radial direction. In the molding surface 18 of the core-mold main portion 11, a ratio Bd/W of a maximum width W lying in regions for shaping sidewall portions and a width Bd in the tire axial direction measured at toe-end shaping positions 18e for shaping toe ends of bead portions is not less than 0.80. In an inside zone 30 from the toe-end shaping position 18e of the molding surface 18 to the position of the maximum width W, the angle α of a tangent T drawn to the molding surface 18 is not more than 15 degrees. The inside zone 30 includes an oblique part 32 in which the angle α of the tangent T is 30 to 45 degrees, and a ratio h/H of a length h in a radial direction of the oblique part 32 and a length H from the toe-end shaping position 18e to an intersecting point P of a line drawn in the tire radial direction from the toe-end shaping position 18e outwardly in the radial direction with the molding surface 18 is less than 0.25.