Square Cross-Section Spring Teeth for Crop Pick-Up Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stiff or ultra-stiff pick-up teeth in crop machinery experience high stress levels leading to yielding and fatigue failures due to concentrated load distribution, resulting in short tooth life, despite their superior crop feeding performance.
Innovation Solution
The use of spring teeth with a square cross-section and parallel flat sides oriented perpendicular to the direction of movement, combined with rounded corners to reduce stress concentrations, provides improved stiffness, dampening, and stress distribution, enhancing crop interaction and reducing geometrical stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stiff or ultra-stiff pick-up teeth are used to improve crop feeding performance, then crop feeding performance is improved, but stress levels increase leading to yielding and fatigue failures
Solution Approach 1:
The patent applies asymmetry by changing the wire cross-section from circular to square or rectangular, and by orienting the flats at specific angles (0-45 degrees from vertical) to create asymmetric stress distribution that redirects maximum stresses away from the coil inner and outer diameters toward the neutral axis, thereby maintaining stiffness while reducing fatigue failures
Solution Approach 2:
The patent changes the geometric parameters of the wire cross-section from circular to square/rectangular with specific flat orientations, and modifies the coil geometry parameters (inner diameter, outer diameter, wire diameter ratios) to optimize stress distribution while maintaining the required stiffness for crop feeding performance
2Ease of operation
If spring coil joined to tines rotates about instant center under load, then the tooth can flex, but load becomes concentrated between first coil and channel leg causing breakage
Solution Approach 1:
The asymmetric square/rectangular cross-section with oriented flats creates a preferred rotation axis that aligns with the channel leg contact point, allowing the coil to rotate smoothly while distributing loads more evenly and preventing concentration at the first coil position
Solution Approach 2:
The patent applies curvature by rounding the corners of the square/rectangular cross-section, which reduces geometrical stress concentrations at the transitions between flats and curved surfaces, thereby preventing stress concentration at the coil inner and outer diameters
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 design significantly extends the operational life of the teeth by distributing stress more evenly and reducing geometrical stress concentrations, resulting in a longer fatigue life and improved crop handling efficiency.
Implementation Method 1
Pick-up teeth are designed to flex out of the way of obstacles and relieve overload stresses
Implementation Method 2
the torsion spring teeth using inter-coil and coil-to-mounting surface friction to produce dampening
Implementation Method 3
the rubber mounted teeth use the dampening nature of the rubber to slow the rebound of the tine
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Spring teeth (84) for a harvesting machine (10) are each constructed of spring wire having a square cross section and being wound so as to define a coil torsion spring section (88) terminating in a tine (86), with the tine having a leading flat surface (a), considered relative to the engagement of tine with the crop during pickup operation, and having a trailing flat surface (b) disposed parallel to said leading flat surface. The coil torsion spring is mounted to a tooth bar (80) formed as a channel member such that the outer surface of the coils make a relatively large area contact with the tooth bar at location (116) spaced approximately 180° from where the tine joins the coil torsion spring. This together with the fact that the contact area of the flat sides of the wire in the coil region is also quite large leads to a damping action that lessens stress in the tooth assembly.