Baler Packer Crank Assembly With Tapered Splines and Static Balance
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Solution Overview
Problem
Crank shaft-operated packer mechanisms in agricultural balers face issues such as weak spots due to welding, premature failure from torsion forces, and static instability, especially with more than two eccentric crank pins, leading to insufficient robustness and difficulty in assembly and disassembly.
Innovation Solution
A crank-operated packer mechanism utilizing a tapered spline connection between crank pins and arms, allowing for separate optimization of design and material choice, with a locking feature and statically balanced crank arms for enhanced stability and ease of assembly/disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If welded crank shafts are used, then the structure is simple and integrated, but the shaft exhibits weak spots due to welding and is vulnerable to premature failure from torsion forces
Solution Approach 1:
The crank shaft is divided into separate components (crank arms and crank pins) that are assembled together using tapered spline connections and locking features. This segmentation eliminates welding weak spots while maintaining structural integrity, allowing each component to be optimized independently for strength and durability.
2Reliability
If assembled crank shafts are used, then welding weak spots are eliminated, but the shaft is often insufficiently robust and/or difficult to assemble and disassemble
Solution Approach 1:
The crank pins are pre-formed with tapered external splines and the crank arms have corresponding tapered internal splines with locking features. This preliminary preparation of mating surfaces enables robust connection while facilitating straightforward assembly and disassembly through the locking mechanisms, eliminating the need for complex welding or permanent fastening.
3Productivity
If crank shafts with more than 2 eccentric crank pins are used, then the packing function is improved, but the shaft becomes statically unstable leading to premature wear and possible failure
Solution Approach 1:
The crank arms are designed with counterbalancing features that offset the static instability caused by multiple eccentric crank pins. This counterbalancing allows the shaft to maintain static stability while supporting more than two crank pins, thereby improving the packing function without sacrificing structural stability.
4Ease of manufacture
If identical crank pins are used (integer multiple of tapered spline features), then production cost decreases and replacement is simplified, but the connection complexity increases
Solution Approach 1:
The crank pins are designed with identical tapered external splines that can mate with multiple crank arms having corresponding internal splines. This universal design allows any crank pin to replace any other crank pin, simplifying inventory management and replacement procedures while the standardized tapered spline interface maintains connection simplicity despite the ability to support multiple configurations.
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 solution provides a robust and durable crank shaft with improved mechanical resistance, reduced wear, and simplified replacement, addressing the weaknesses of existing mechanisms by enabling a strong connection while allowing for cost-effective production and maintenance.
Implementation Method 1
The connection comprises tapered spline features on the outer ends of the crank pins and in openings provided at the outer ends of the crank arms, which interlock when the crank pins are inserted in the openings
Implementation Method 2
The connection further comprises a locking feature for locking the connection, such as a locking nut screwed onto a threaded outer end of the pin when the latter is inserted into an opening of a crank arm
Data Source
AI summary
A crank-operated packer mechanism includes crank pins and crank arms assembled by a tapered spline connection. The connection includes tapered spline features on outer ends of the crank pins and in openings provided at outer ends of the crank arms, which interlock when the crank pins are inserted in the openings. The connection further includes a locking feature for locking the connection, such as a locking nut screwed onto a threaded outer end of the crank pins when inserted into the opening. Fixing of rotary bearings onto the crank pins is done by a fixing nut which at the same time serves as a disassembling aid for the spline connection. The crank arms are shaped in a way that deviates from a straight shape to such an extent that the crank shaft is statically balanced about its central rotation axis. Also a baler including the aforementioned packer mechanism.