Pneumatic Tire Sidewall-Over-Tread Manufacturing Method
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Solution Overview
Problem
The existing methods for manufacturing pneumatic tires with a sidewall-over-tread structure face challenges in forming a conductive layer without collapsing wound strips, affecting force variation, and requiring complex and costly stitch-down processes, which decrease productivity and result in defective products.
Innovation Solution
The method involves forming a pneumatic tire with a sidewall-over-tread structure by using rubber strips of specific resistances for the sides and center tread, ensuring a conductive layer is formed at the shoulder portion, eliminating the need for stitch-down, and maintaining shape accuracy and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber strips having low solid specific resistance are stacked thin along the tread layer to form a conductive layer, then electric conductivity is ensured, but the wound strip collapses and productivity decreases
Solution Approach 1:
The patent changes the parameter of solid specific resistance by using rubber strips with low solid specific resistance (≤1×10^7 Ω·cm) for the sides of tread, while using rubber strips with high solid specific resistance (>1×10^7 Ω·cm) for the center of tread. This parameter differentiation allows the conductive layer to be formed effectively without collapsing the wound strips, thus maintaining both electric conductivity and productivity.
2Manufacturing precision
If the stitch-down step is used to press the sides of tread to extend along the curved side surface, then the tread is pressure-bonded to the first cover with no gap, but the process becomes complex and costly
Solution Approach 1:
The patent extracts and eliminates the stitch-down step from the manufacturing process. By forming the sides of tread separately on the first forming drum with appropriate rubber strip selection, the need for the complex stitch-down process is removed entirely, while still achieving proper pressure bonding between the tread and first cover.
Solution Approach 2:
The patent performs preliminary action by forming the sides of tread with the correct rubber strip properties during the initial strip-winding step on the first forming drum. This preliminary preparation ensures that the tread can be properly bonded to the first cover without requiring subsequent stitch-down operations.
3Stability of the object's composition
If rubber strips of high solid specific resistance are used for the center of tread, then the wound strip maintains stability, but the conductive layer formation becomes difficult
Solution Approach 1:
The patent applies local quality by differentiating the rubber strip properties for different regions of the tread. The center of tread uses high solid specific resistance rubber strips for stability, while the sides of tread use low solid specific resistance rubber strips for conductive layer formation. This localized differentiation resolves the contradiction between stability and ease of conductive layer formation.
Data Source
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AI summary
A pneumatic tire manufacturing method is provided in which winding collapse is prevented, there is no possibility of adverse effects on the FV, a current-carrying layer can be formed easily, and down-stitching can be dispensed with or minimized in the manufacture of SOT-structure pneumatic tires having a base-pen structure in the tread. This pneumatic tire manufacturing method involves: a step in which a sidewall, an inner liner, and a ply are bonded on a first molding drum, beads are set, and the tread side part that will form the current-carrying layer is formed on the side wall, forming a first cover; a step in which a breaker and band are bonded on a second molding drum and the tread center part is formed on the band, shaping the tread ring; a step in which the first cover is inserted inside of the tread ring and inflated to bond to the tread ring with pressure; and a step in which the sidewall is bonded to the lateral surface of the first cover, and the tread side part and the tread center part are bonded together.