Polyurethane Tire Retreading with Cone Spreader and Chemlok Bonding
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Solution Overview
Problem
Existing methods for retreading large tires, such as earth mover tires, with polyurethane treads are labor-intensive and often result in poor bonding, leading to separation under load and heat, and fail to produce tires with consistent quality and life expectancy.
Innovation Solution
A process involving the use of a Chemlok primer and adhesive, followed by inflation of the tire carcass and molding with polyurethane materials in a heated mold, ensuring a molecular bond and homogeneous distribution to prevent voids and air pockets, with a post-curing step to enhance the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber recapping techniques are used for large tires, then the process can be performed with conventional materials, but the bonding is unstable and the tire separates under heat and load
Solution Approach 1:
The patent changes the material parameters by using polyurethane instead of conventional rubber, and modifies the chemical composition by incorporating specific primers and adhesives. This parameter change enables stable bonding that resists separation under heat and load, directly resolving the reliability issue while maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite bonding system by combining polyurethane tread material with specifically formulated primers and adhesives. This composite approach ensures molecular-level bonding between the tread and tire carcass, preventing separation under operational conditions while providing a practical manufacturing process
2Manufacturing precision
If polyurethane material is poured into the mold cavity, then the tread can be formed, but air pockets and voids are created that compromise quality
Solution Approach 1:
The patent applies preliminary action by pre-heating the mold cavity and preparing the polyurethane material before pouring. This preliminary preparation ensures proper flow characteristics and eliminates air pockets, achieving uniform tread formation without requiring overly complex molding equipment
Solution Approach 2:
The patent changes the temperature parameter by maintaining the mold cavity at a specific temperature range during pouring. This parameter control ensures the polyurethane material flows properly and eliminates voids, achieving high manufacturing precision while keeping the process manageable
3Reliability
If the tire carcass is ground and cleaned thoroughly, then the surface is prepared for bonding, but the process becomes labor intensive and time consuming
Solution Approach 1:
The patent replaces manual mechanical cleaning operations with automated grinding and cleaning equipment. This substitution maintains thorough surface preparation for optimal bonding strength while significantly reducing labor intensity and increasing retreading speed, resolving the productivity contradiction
4Productivity
If the polyurethane tread is cured quickly in the mold, then the retreading process is faster, but the bond strength and tire life are compromised
Solution Approach 1:
The patent optimizes the curing parameters by controlling temperature and time within specific ranges. This parameter optimization achieves adequate bond strength and tire life while maintaining reasonable production speed, resolving the contradiction between productivity and strength requirements
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 method provides a stable and durable polyurethane tread that maintains tire integrity under heavy loads and harsh conditions, offering improved cut resistance and extended tire life comparable to new conventional rubber tires.
Implementation Method 1
passing polyurethane materials into the mold cavity containing the carcass, off of an edge of a cone that directs an even distribution of the materials along the mold hub area and across the mold cavity to fill the mold cavity from bottom to top, forming the carcass tread, providing for pushing air from the mold cavity ahead of the pour
Implementation Method 2
the mold is heated to approximately one hundred eighty (180) degrees F... After approximately a fifteen (15) minute cure... the now retreaded tire carcass is removed from the mold and is post cured at a temperature of approximately one hundred seventy five (175) degrees F.
Implementation Method 3
adhesive, preferably a Chemlock® also manufactured sold by Rohm and Hass Company, of Philadelphia, PA that provides for bonding between polyurethane and rubber surfaces... The combination of the selected primer and adhesive provides for conditioning the carcass prepared tread area surface to securely and permanently bond to the tread of polyurethane material cast thereto
Data Source
AI summary
A process and method for retreading a heavy duty tire with a polyurethane tread where, after a tire carcass is inspected, cleaned and the worn tire tread is removed, the tire carcass receives a tube fitted therein and is installed in a mold cavity, between top and bottom mold rings. The mold rings each include spaced segments that inter-digitate and will form equal spaced tread voids in a finished recapped tire. The bottom mold ring inner edge top includes a continuous sealing lug, and the top ring is open to pass a flow of polyurethane materials, that is received off of a lower edge of a cone shaped spreader positioned onto the tire carcass top side wall and slides, as a sheet, into the mold, filling the mold cavity from bottom to top, forcing air from the mold ahead of the fill and forming the recapped tire tread.