Self-Locking Tire Mold With Elastic Shoulder Spacer
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Solution Overview
Problem
Self-locking molds used in tire vulcanization require additional external components to maintain closure under internal pressure, and altering tire designs complicates the collaboration between sectors and shells, leading to friction issues.
Innovation Solution
A self-locking mold design featuring shells and sectors with complementary frustoconical surfaces and elastic means, such as springs, to maintain a sufficient distance and reduce friction, allowing the mold to remain closed without external aids and accommodate design changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If frustoconical bearing surfaces are used to compensate internal pressure, then the mold remains closed under pressure, but friction occurs at the interfaces between components
Solution Approach 1:
A shoulder spacer is introduced as an intermediary component between the shell and sectors. The spacer includes a frustoconical bearing surface that contacts the shell's frustoconical surface, mediating the force transmission and preventing direct frictional contact between the shell and sector interfaces.
Solution Approach 2:
The mold is segmented into distinct functional components: shell, shoulder spacer, and sectors. Each component has specialized surfaces for its function, with the shoulder spacer specifically designed to handle the friction-prone interface through its frustoconical bearing surface, separating the force-bearing function from the molding function.
2Force
If additional external components are used to maintain mold closure, then the mold remains closed under internal pressure, but the device complexity increases
Solution Approach 1:
The shoulder spacer merges multiple functions into a single component: it provides the frustoconical bearing surface for force compensation, acts as a mechanical interface between shell and sectors, and includes features for locking and positioning. This consolidation reduces the need for separate components while maintaining closure force.
Solution Approach 2:
The frustoconical bearing surfaces on the shoulder spacer and shell automatically compensate for internal pressure through their geometric design. The self-locking feature arises from the frustoconical geometry itself, which converts radial pressure into axial locking force without requiring additional active components or external mechanisms.
3Adaptability or versatility
If the tire design is altered to change tread width relative to sidewall, then design versatility is improved, but friction between sector and shell interfaces increases
Solution Approach 1:
The shoulder spacer acts as a mediator that decouples the geometric relationship between shell and sectors. By providing its own frustoconical bearing surface, it allows the shell and sectors to maintain their relative positions and functions regardless of tire design variations, preventing friction caused by design alterations.
Solution Approach 2:
The shoulder spacer with its frustoconical bearing surface provides a universal interface that works across different tire designs. The frustoconical geometry universally converts radial pressure into axial force regardless of the specific tire dimensions, making the solution adaptable to various tread widths and sidewall configurations without increasing friction.
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
The mold effectively resists internal pressure without additional components, maintains tight tolerances, and reduces friction during opening and closing, enabling adaptable tire designs while preserving the benefits of self-locking molds.
Implementation Method 1
The mold also includes an elastic means that maintains a space between each shoulder spacer and a respective inner lateral boundary, wherein maintaining the space corresponds to maintaining a distance sufficient to cause each shoulder spacer to avoid friction along an interface between the shoulder spacer and the sector
Implementation Method 2
For certain embodiments, the elastic means includes one or more springs.
Implementation Method 3
The angle α is calculated so that the effect of the internal pressure P on the shells 14 (tending to impart axial movement to the shells 14 as indicated by the arrows A) is dominant with respect to the effect of the pressure on sectors 12 (tending to impart radial movement to the sectors 12, as indicated by arrow B).
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A self-locking mold (100) includes sectors (108) circumferentially distributed around a shell (102) to resist internal pressure and remain in the closed position without the aid of additional components during curing. The mold (100) includes shoulder spacers (120) that, in the closed position of the mold, are arranged between the shell (102) and the sectors (108). An elastic means (130) is employed so as to avoid friction between them.