Pneumatic Tire Vent Piece for Spew Suppression
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Solution Overview
Problem
Existing methods for air venting in vulcanization molding of pneumatic tires, such as dividing the mold or using spring vents, face limitations in flexibility and location restrictions, leading to spew occurrence and undesirable external appearances.
Innovation Solution
A pillar-shaped vent piece without axial holes is embedded in the vulcanization mold, allowing air venting through a gap between the vent piece and the mold's side face, with optional saw-cuts, vent lines, and twill knurling for improved air release and secure embedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent hole is provided in the vulcanization mold or a vent piece is embedded, then air vent can be performed, but spew occurs due to rubber extruding into the vent hole
Solution Approach 1:
The vent piece is divided into a body portion and a protruding portion, with the protruding portion extending into the mold to create a restricted vent channel. This segmentation allows air venting while preventing rubber extrusion that causes spew.
Solution Approach 2:
Instead of providing a simple open vent hole, the invention inverts the approach by embedding a protruding portion into the mold that actively blocks rubber extrusion while maintaining air passage, transforming the vent structure from passive to active spew prevention.
2Reliability
If the mold is divided into a plurality, then air vent can be performed through gaps between mating surfaces, but the vent location is determined in initial design and cannot be added later
Solution Approach 1:
The vent piece is designed as a separate embeddable component with a prepared hole structure, allowing it to be installed at any location during mold preparation or even later, providing flexibility in vent location selection without requiring complete mold redesign.
3Reliability
If the mold is divided into an excessively large number, then air vent can be improved, but the mold cannot tolerate pressurization and distortion occurs
Solution Approach 1:
The vent function is segmented into discrete vent pieces that can be strategically placed, allowing effective air venting with fewer locations compared to dividing the entire mold, thereby maintaining mold structural integrity under pressurization.
4Reliability
If a spring vent is used, then air vent can be performed with a valve element and spring, but the diameter becomes large (2.0 to 4.0 mm) causing restriction in location for orderly arrangement
Solution Approach 1:
The complex spring and valve element structure is extracted and replaced with a simpler protruding portion design that achieves the same air venting function with a much smaller diameter, enabling flexible arrangement at various mold locations without spatial restrictions.
Solution Approach 2:
The vent piece is designed as a simple, inexpensive protruding structure without complex moving parts like springs, making it easier to manufacture and install at multiple locations without concern for cost or complexity, effectively replacing the more expensive spring vent mechanism.
Data Source
AI summary
Provided are: vent pieces, which can easily be added later and with which the occurrence of spew can be suppressed without restriction in the locations where the vent pieces can be orderly arranged in vulcanized molding of a pneumatic tire; and a manufacturing method for pneumatic tire in which vulcanization molding of a raw cover is performed by using a vulcanization mold in which said vent piece has been embedded. A vent piece, which is used by being embedded in a prepared hole for air vent provided on the inner surface of a pneumatic tire vulcanization mold, is a cylinder without a hole in the axial direction and is configured to perform air vent from a gap formed between the vent piece and the side surface of the prepared hole. A vent piece has a saw cut extending in the axial direction formed on the side surface of the cylinder.