Underfluid Pelletizer Quick Disconnect Hub and Pin Drive Mechanism
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Solution Overview
Problem
Existing pelletizer designs face issues with torque transmission, drive key breakage, wear patterns, and polymer agglomeration, leading to impaired performance, costly failures, and safety hazards during maintenance.
Innovation Solution
A cutter hub drive mechanism using longitudinally extending grooves and drive pins for torque transmission, combined with a quick disconnect hub to simplify the removal of the pelletizer shaft from the cutting chamber, preventing fines entry and reducing wear, and allowing easy disconnection and reconnection without complex disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If keys are welded to the cutter hub holder to transmit torque, then torque transmission is achieved, but the keys can break loose from the weld and wear into the key slots creating hook patterns that trap the keys
Solution Approach 1:
The drive mechanism is segmented into multiple drive pins (typically 3-6) distributed around the cutter hub holder, each independently positioned in drive pin channels. This segmentation eliminates the single-point failure mode of welded keys while distributing torque transmission across multiple contact points, preventing any single pin from bearing excessive stress that could cause breakage or wear-induced hook patterns.
Solution Approach 2:
The welded key mechanical connection is replaced with a precision-machined drive pin system that fits into corresponding channels. This substitution eliminates the welding process entirely, replacing it with a precision-fit mechanical system where drive pins are retained by shoulders and set screws within the cutter hub holder, providing reliable torque transmission without the risks of weld failure or key wear.
2Power
If keys are used for torque transmission, then the cutter hub can be driven, but fines accumulate in the key slots locking the cutter hub holder in place and preventing adjustment
Solution Approach 1:
The drive pins are extracted from the confined key slot geometry and positioned in open drive pin channels that extend through the cutter hub holder. This extraction eliminates the enclosed slot structure where fines could accumulate and lock the mechanism, allowing fines to be easily flushed out through the open channel geometry while maintaining effective torque transmission through the drive pins.
Solution Approach 2:
The drive pin channels serve as an intermediary structure that separates the torque transmission function from the adjustment function. The channels provide a controlled pathway that allows fines to be flushed out while the drive pins maintain their torque transmission role, preventing the locking mechanism that occurs when fines accumulate in enclosed key slots.
3Strength
If the pelletizer shaft is bolted to the motor shaft with set screws, then the connection is secure, but it requires complex disassembly to remove the pelletizer for maintenance when polymer agglomerates
Solution Approach 1:
The connection system is made dynamic through the use of a quick disconnect hub that can be rapidly engaged and disengaged. The hub features a splined interface that provides secure torque transmission during operation but can be quickly released by actuating a release mechanism, allowing the pelletizer to be removed for maintenance without the complex disassembly of multiple set screws and bolts.
Solution Approach 2:
The shaft connection is segmented into modular components: the motor shaft with its mounting flange, the quick disconnect hub with splined interface, and the pelletizer shaft. This segmentation allows the hub to be independently removed from the pelletizer shaft while remaining attached to the motor shaft, enabling rapid maintenance access without disturbing the motor mounting.
4Power
If multiple keys are used to prevent torque overload, then torque capacity increases, but more keys increase the complexity of the drive mechanism and the likelihood of key breakage
Solution Approach 1:
The drive pin system serves multiple functions simultaneously: it transmits torque, provides positioning through the drive pin channels, and allows for easy replacement without affecting other components. The standardized drive pin design with shoulders and set screw retention provides a universal solution that simplifies the overall mechanism while maintaining high torque capacity through the distributed pin arrangement.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6A
AI summary
An underwater pelletizer for extruding and cutting a process melt into pellets, comprising a pelletizer shaft (300) rotationally driven by a motor (390), a die plate (359) with a plurality of extrusion orifices formed therein, a rotary cutter blade assembly in opposed relation to said cutting face, said rotary cutter blade assembly having a cutter hub (350) with at least one blade (335) mounted thereon, a cutter hub drive mechanism, a cutting chamber (355) enclosing said cutting face and cutter blade assembly. A quick disconnect hub (320) is configured to removably couple the pelletizer shaft to the cutter hub holder (315), wherein a separable connection between said quick disconnect hub (320) and the pelletizer shaft (300) is configured to allow for separating the pelletizer shaft from the cutter hub holder.