Self-locking tire vulcanizing mold lever arm design
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Solution Overview
Problem
The existing self-locking molds for vulcanizing wide tires require significant material and mass to maintain closure under pressure, leading to high production costs and potential circumferential clearances due to radial deformation of sectors.
Innovation Solution
Adjusting the lever arm between frustoconical surfaces to balance torques and forces, allowing for reduced material usage and minimizing radial deformation, with optional force limiting means to manage pressure thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mold uses self-locking mechanism with frustoconical surfaces to maintain closure under pressure, then the mold remains closed without external parts, but the quantity of material required increases significantly
Solution Approach 1:
The patent balances the torques acting on the sectors by carefully selecting the angle α of the frustoconical surfaces. This creates an equipotential state where the torque from internal pressure (trying to open the mold) is counterbalanced by the torque from the closing forces on the frustoconical surfaces, allowing the mold to remain closed with minimal material
Solution Approach 2:
The patent changes the geometric parameter α (the angle of the frustoconical surfaces) to optimize the balance between opening and closing torques. By adjusting this parameter, the mold achieves stable closure with reduced material quantity, as the optimal angle creates the most efficient force balance
2Manufacturing precision
If the radial thickness of sectors is increased to prevent circumferential clearances, then intersectoral contact is maintained, but the mass and production cost increase
Solution Approach 1:
By balancing the torques on the sectors, the patent creates a state where the sectors are equally likely to move in either direction (open or closed). This equilibrium prevents the sectors from deforming radially outward under pressure, maintaining precise intersectoral contact without requiring excessive radial thickness
Solution Approach 2:
The patent applies preliminary closing forces through the frustoconical surfaces that counteract the opening forces before circumferential clearances can develop. This preliminary anti-action prevents radial deformation of the sectors, maintaining precision without increasing mass
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 reduces the material necessary for mold closure while maintaining effective intersectoral contact, minimizing radial thickness and preventing circumferential clearances, thus lowering production costs and ensuring precise tire molding.
Implementation Method 1
The mold comprises frustoconical bearing surfaces on the edges of said sectors and of said shells. Said frustoconical surfaces are inclined at an angle α relative to the axis of the mold
Implementation Method 2
the effect of the internal pressure on the shells which tends to bring the sectors closer to the center of the mold, is preponderant compared to the effect of the internal pressure on the sectors which tends to spread the sectors radially apart
Implementation Method 3
the resultant of the forces at this point of contact applied with a lever arm equal to a, generates at the level of the sector a torque CF of opposite direction to the torque CP generated on the sector by the pressure forces
Data Source
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AI summary
The invention relates to a segmented mold for molding and vulcanizing a tire having a given diameter (Ds), which has a width (L) and a diameter (J) at the connecting point (E), and which comprises shells (1, 1') and segments (2) that engage so as to resist internal pressure and remain in a closed position without the aid of additional parts, wherein each segment (2) comprises, on the side edges thereof, a projection (26) which extends radially inward and which has an edge extending axially into the mold and having a frustoconical surface (20) inclined at a given angle (a) relative to the axis (XX') of the mold such that the extensions of the outlines of each frustoconical surface on a meridian plane are cut on the radially inner side of the segment in question, wherein each shell (1, 1') comprises a projection (16) which extends radially outward and which has an edge having a frustoconical surface (10) inclined at a single angle a relative to the axis XX' of the mold. The distance (a) between a straight line (tt'), which is parallel to the axis of the mold and passing through the point (T) of application of the forces (F) resulting from the contact between the shells and the segments, and a straight line (ss'), which is parallel to the axis of the mold and extending away from the inner surface of the resistant segment, is equal to k * 0.42 * D (L/J)2 l, with a coefficient k of between 0.8 and 1.4.