Magnetic Coupling for Granulator Knife Alignment
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Solution Overview
Problem
Prior extruders for pet food production suffer from inconsistent distance between the die and knives due to drive axis tilting, leading to low product quality, especially under increased internal pressure which can cause deformation and misalignment.
Innovation Solution
Decoupling the drive from the knife's bearing and using a magnetic coupling to transmit torque, allowing for adjustable alignment and maintaining a consistent distance through axial movement and spring preloading, ensuring the knife is pressed against the die with minimal distance for high-quality cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drive is rigidly connected to the knife shaft, then the structure is simple and easy to manufacture, but the distance between the knife and die becomes uneven during rotation due to axis tilting under pressure
Solution Approach 1:
The patent replaces the direct mechanical connection between drive and knife with a magnetic coupling system. The drive shaft magnetically couples to the knife shaft through magnetic attraction across a small air gap, eliminating rigid mechanical constraints. This allows the knife shaft to maintain its rotational axis independently while still being driven, preventing distance variation between knife and die during rotation.
Solution Approach 2:
The magnetic field acts as an intermediary between the drive shaft and knife shaft. Instead of direct mechanical contact, torque is transmitted through magnetic forces across the air gap. This intermediary mechanism decouples the drive from the knife positioning, allowing precise distance control while maintaining simple structural design.
2Manufacturing precision
If the drive is decoupled from the knife bearing using magnetic coupling, then the distance consistency between knife and die is maintained under pressure, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical alignment and bearing support systems with a simpler magnetic coupling mechanism. The magnetic coupling naturally maintains constant torque transmission and consistent spacing without requiring complex mechanical alignment features, bearing housings, or adjustment mechanisms.
Solution Approach 2:
The patent changes the physical state of torque transmission from mechanical contact to magnetic field interaction. By operating in the magnetic domain rather than mechanical contact domain, the system achieves precise distance control while reducing mechanical complexity. The air gap distance becomes a controllable parameter that maintains consistency under varying pressure conditions.
3Reliability
If internal pressure is increased to prevent water evaporation during extrusion, then product quality improves, but the housing deforms causing drive axis tilting and knife misalignment
Solution Approach 1:
The patent extracts the drive mechanism from the pressurized housing environment. The magnetic coupling allows the drive shaft to be positioned outside or independently of the pressure chamber, so that pressure-induced housing deformation does not affect the drive axis alignment. The magnetic field transmits torque through the housing wall or across an isolated interface, decoupling pressure effects from alignment precision.
Solution Approach 2:
The magnetic field serves as an intermediary that transmits rotational force from the drive to the knife shaft without being affected by pressure-induced housing deformation. This intermediary mechanism maintains consistent torque transmission and knife alignment even when the housing structure deforms under high internal pressure.
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 configuration maintains a consistent and minimal distance between the knife and die, even under high internal pressure, preventing product deformation and ensuring high-quality cuts without affecting the extrusion process, allowing for efficient production of pet food with reduced flakes and improved product quality.
Implementation Method 1
a first part of the magnetic coupling (26) is connected to the motor (7) in a rotationally fixed manner and a second part of the magnetic coupling (26) is connected to the knife (5) in a rotationally fixed manner and the two parts of the magnetic coupling are spaced apart in axial direction
Implementation Method 2
the torque can be transmitted via the magnetic coupling from the drive to the knife even with small deviations between the axis of rotation of the drive and the knife
Data Source
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AI summary
Apparatus (1) for cutting off extrudate produced with an extruder (2) having a die with at least one opening (4), comprising a knife (5) which is mounted rotatably about an axis of rotation (6) and which can be driven by a drive, in particular an electric motor (7), in that a torque is transmitted from the drive to the knife (5). A bearing element (8) is provided which can be rigidly connected to the extruder (2) and via which the knife (5) can be rotatably connected to the extruder (2) around the axis of rotation (6), whereby the drive can be placed separately from the bearing element (8) and a magnetic coupling is provided between the bearing element (8) and the drive in order to transmit the torque from the drive to the knife (5) via magnetic forces.