Rake Wheel Tine Wear Reduction Using Plastic Support Band
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Solution Overview
Problem
Existing rake wheel assemblies experience premature tine failure due to wear and noise caused by the combination of relative movement and steel-on-steel contact between tines and support bands, especially in tough raking conditions like those encountered with crop residues.
Innovation Solution
The use of a support band made from a material other than steel, such as ultrahigh molecular weight polyethylene (UHMW) or NYLON, which reduces the coefficient of friction and provides additional cushioning, minimizing wear and noise by allowing tines to move and rotate freely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel support band is used with steel tines, then the structure is strong and rigid, but wear and noise increase due to steel-on-steel contact
Solution Approach 1:
The support band is constructed as a composite structure with a steel substrate providing structural strength and rigidity, and a plastic coating layer (such as UHMWPE or nylon) providing low-friction contact surfaces. This composite material approach allows the band to maintain mechanical strength while reducing wear on steel tines through the plastic contact interface.
Solution Approach 2:
The plastic coating on the support band acts as an intermediary material between the steel tines and the steel band substrate. This intermediate plastic layer reduces direct metal-to-metal contact, thereby minimizing wear and noise while allowing the steel substrate to maintain structural integrity.
2Strength
If a steel support band is used, then the band is rigid and strong, but noise and wear increase due to friction and relative movement
Solution Approach 1:
The support band combines steel and plastic materials to create a composite structure where the steel substrate provides strength and rigidity, while the plastic coating reduces harmful friction-related effects such as noise and wear during operation.
Solution Approach 2:
The plastic coating changes the surface friction parameter of the support band from high (steel-on-steel) to low (steel-on-plastic), thereby reducing wear and noise generation while maintaining the structural parameters provided by the steel substrate.
3Reliability
If tines are allowed to move freely on the support band, then wear and noise are reduced, but tine stability may be compromised
Solution Approach 1:
The plastic coating modifies the friction parameter to an optimal level that allows controlled movement - sufficient to reduce wear and noise through reduced friction, but not so low as to compromise tine stability during operation.
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 solution extends the life of rake tines, reduces noise, and improves reliability by distributing loads more evenly along the tine length, thereby reducing stress concentrations and torque loads.
Implementation Method 1
reduces the coefficient of friction and provides additional cushioning, minimizing wear and noise by allowing tines to move and rotate freely
Implementation Method 2
provides additional cushioning, minimizing wear and noise by allowing tines to move and rotate freely
Data Source
AI summary
A rake wheel has a hub with tines extending outwardly from the hub. The tines extend through evenly spaced openings in a support band. At least the inner periphery of the openings through the support band are made of a material softer than the material of the tines to minimize the wear of the tines where the tines touch the inner periphery of the openings as the tines move with respect to the inner periphery of the openings during the use of the rake wheel.