Underwater Pelletizer Cutter Hub Position Control
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Solution Overview
Problem
Underfluid pelletizers face challenges in achieving repeatable blade adjustments due to manual variability, inconsistent force application, and sensitivity to external influences like transport fluid and polymer lubricity, leading to blade wear and inconsistent pellet production.
Innovation Solution
A cutter hub position control device with a programmable logic controller and a slidable spline drive connection, allowing for precise axial movement of the cutter hub and blades relative to the die face, and incorporating a lockable brake to mitigate external influences, ensuring consistent and reproducible blade positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual adjustment of blades relative to die face is used, then ease of operation is improved, but manufacturing precision deteriorates due to operator variability and inconsistent adjustment intervals
Solution Approach 1:
The patent replaces manual mechanical adjustment with an automated motor-driven system that uses feedback from load sensing devices (amperage sensors or load cells) to automatically position and maintain blade-die face contact force, eliminating operator variability while maintaining ease of operation through automated control
Solution Approach 2:
The system incorporates load sensing feedback mechanisms that continuously monitor the force between blades and die face, using amperage draw from the pelletizer motor or direct load cell measurements to automatically adjust blade position and maintain consistent contact force, thereby improving manufacturing precision
2Ease of operation
If springs are used to hold blades against die face, then ease of operation is improved, but manufacturing precision deteriorates due to inconsistent force application and spring compression variability
Solution Approach 1:
The patent replaces spring-based mechanical force application with an automated motor-driven positioning system that uses feedback control to maintain consistent blade-die face contact force, eliminating the variability inherent in spring compression while preserving ease of operation through automated adjustment
3Ease of operation
If pneumatic cylinder is used to move blades into die plate, then ease of operation is improved, but reliability deteriorates due to compressible air and sensitivity to water influences
Solution Approach 1:
The patent replaces pneumatic cylinder actuation with a motor-driven positioning system that directly controls blade position through a spline connection, eliminating the reliability issues of compressible air and water sensitivity while maintaining automated operation through feedback control from load sensors
Solution Approach 2:
The patent introduces a non-compressible intermediate mechanism (spline drive connection) between the motor and cutter hub that reliably transmits positioning force without the compressibility issues of pneumatic systems, thereby improving reliability while maintaining ease of automated operation
4Ease of operation
If hydraulic cylinder is used to adjust blades, then ease of operation is improved, but device complexity increases due to complicated adjustment mechanisms and expensive pressure controlling components
Solution Approach 1:
The patent replaces complex hydraulic systems with a simpler motor-driven positioning system that uses a spline connection for direct mechanical coupling, eliminating expensive hydraulic pressure controlling components while maintaining automated blade adjustment through feedback control
Solution Approach 2:
The patent extracts and eliminates the complex hydraulic pressure controlling components from the system, retaining only the essential motor-driven positioning mechanism with feedback control, thereby reducing device complexity while preserving ease of automated operation
5Ease of operation
If load sensing devices or amperage load are used for feedback, then ease of operation is improved, but measurement precision deteriorates due to false readings from fluid action and polymer lubricity
Solution Approach 1:
The patent introduces a direct mechanical coupling through a spline drive connection that provides a more reliable feedback mechanism for detecting blade-die face contact, reducing false readings caused by fluid action and polymer lubricity that affect remote load sensing devices
Data Source
Figure 1
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Figure 4a~4f
AI summary
A cutter hub position control device for consistent blade adjustment in an underfluid pelletizer is provided in connection with a motion rod attached to the pelletizer cutter hub and extending through a hollow shaft of the pelletizer motor. The cutter hub position control device can be collinear, transaxial or in a plane parallel to the axis of the motion rod to which it is attached. Adjustment of the cutter hub position control device is automated through use of feedback control mechanisms.