Cylindrical Rubber Member Forming with Dynamic Extrusion Control
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Solution Overview
Problem
Conventional methods for forming cylindrical rubber members face issues such as increased costs, stress relaxation, dimension changes, and level differences at joints, leading to uniformity problems and potential air incorporation or cracking during vulcanization.
Innovation Solution
A method involving winding rubber extruded through a die around a rotation-supporting body, where the extruding amount and distance between the die and the body are controlled to form wedge-shaped cross sections at the start and end, ensuring a consistent thickness and eliminating level differences at the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rubber is cut into a length corresponding to one tire using a cutting device, then the rubber can be conveyed to the forming step, but costs are increased and stress relaxation occurs around the cut portion leading to dimension change and deterioration in tire uniformity
Solution Approach 1:
The patent applies continuous extrusion of rubber without cutting interruptions. The extruder continuously feeds rubber to the forming drum, eliminating the discontinuous cutting and conveying process. This continuous action prevents stress relaxation at cut portions and maintains dimensional consistency throughout the rubber member, thereby improving tire uniformity while reducing manufacturing costs.
2Productivity
If rubber is extruded at high extruding speed to avoid long cycle time in spiral winding, then productivity increases, but rubber burns by generation of heat
Solution Approach 1:
The patent employs dynamic control of the extrusion process by gradually increasing the extrusion speed from zero to the target speed during the winding start step, maintaining constant speed during the winding step, and gradually decreasing speed at the winding end step. This dynamic speed adjustment prevents excessive heat generation that would cause rubber burning while maintaining high productivity through optimized extrusion rates.
3Ease of manufacture
If a long distance is maintained from the extruder to the die in conventional forming methods, then the die can be positioned for extrusion, but the temperature of the molten rubber drops increasing rubber viscosity and making it difficult to obtain desired rubber thickness
Solution Approach 1:
The patent extracts the die from the conventional long-distance positioning system and integrates it directly with the forming drum surface. The die is positioned immediately adjacent to the drum where rubber is deposited, eliminating the long transport distance. This extraction of the die from the distant positioning system prevents temperature drop and viscosity increase, ensuring consistent rubber thickness is maintained throughout the forming process.
4Manufacturing precision
If the die is brought close to the rotation-supporting body with controlled extruding amount, then uniform thickness and width are maintained, but the process complexity increases with multiple steps
Solution Approach 1:
The patent implements periodic action through three distinct operational phases: the winding start step with gradually increasing extrusion speed, the winding step with constant extrusion speed, and the winding end step with gradually decreasing speed. This periodic variation in extrusion parameters ensures uniform rubber thickness and width while maintaining relatively simple equipment configuration, as the complexity is managed through controlled temporal variations rather than spatial complexity.
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 method maintains uniform thickness and width, preventing air incorporation and enhancing tire uniformity by eliminating level differences at the joint, thus improving the manufacturing process for cylindrical rubber members.
Implementation Method 1
rubber extruded by an extruder through a die
Implementation Method 2
rubber is wound around a rotation-supporting body
Data Source
AI summary
A method for forming a cylindrical rubber member includes bringing a die 11 close to a forming drum 2, forming a winding start portion S1 by extruding a rubber S and simultaneously starting to rotate the forming drum 2 to gradually increase an extruding amount to an amount Q1 and gradually increase a distance between the die 11 and the forming drum 2 to a distance D2 corresponding to a desired thickness of the cylindrical rubber member, winding the rubber S by maintaining the extruding amount at the amount Q1, and maintaining the distance between the die 11 and the forming drum 2 at the distance D2, and forming a winding end portion S2 on the winding start portion S1 by maintaining the distance between the die 11 and the forming drum 2 at the distance D2 and gradually reducing the extruding amount from the amount Q1.