Pelletizer Cutter Head Axial Adjustment via Direct Drive Shaft
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Solution Overview
Problem
Existing pelletizer designs face challenges in achieving rigid and energy-efficient axial adjustment of the cutter head without compromising the compact design or requiring a specially designed main drive.
Innovation Solution
The spindle drive stage is placed directly on the drive shaft between the main drive motor and the cutter head, allowing the drive shaft to be axially adjusted, thereby eliminating the need for a motion rod and allowing for a compact design without the need for a hollow-shaft motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pneumatic cylinder is used to adjust the cutter head axially, then lower fluctuations of holding torque are achieved, but high efficiency losses occur due to the pneumatic drive
Solution Approach 1:
The patent replaces the pneumatic cylinder with a direct motor-driven mechanism where the drive shaft itself is made axially adjustable. The motor (5) directly drives the cutter head (2) through the adjustable drive shaft (4), eliminating the pneumatic drive system and its associated energy losses while maintaining stable holding torque through direct mechanical coupling.
Solution Approach 2:
The drive shaft (4) is designed to perform multiple functions: it transmits rotational motion from the motor to the cutter head while simultaneously providing axial adjustment capability. This integration of rotation and axial movement in a single component eliminates the need for separate pneumatic adjustment mechanisms.
2Ease of operation
If a rack and pinion mechanism is used for axial adjustment, then the cutter head can be adjusted, but stresses in the bearing arrangement lead to losses in rigidity and efficiency
Solution Approach 1:
The patent extracts the rack and pinion mechanism from the system and replaces it with a simplified direct-drive approach. The drive shaft (4) is made directly adjustable axially without intermediate transmission mechanisms, removing the source of bearing stresses and rigidity losses.
Solution Approach 2:
Instead of using a rack and pinion to convert rotational motion to axial movement, the patent inverts the approach by making the drive shaft itself axially adjustable while maintaining direct rotational drive. The motor (5) directly drives the cutter head through the adjustable shaft, reversing the traditional mechanism sequence.
3Ease of operation
If a hollow-shaft motor is used to accommodate the motion rod, then the cutter head can be adjusted axially, but the design becomes less compact
Solution Approach 1:
The patent merges the axial adjustment function and rotational drive function into a single integrated drive shaft (4). The drive shaft is made both axially adjustable and rotatable, combining what were previously separate functions (motion rod in hollow shaft) into one component, thereby achieving compactness.
Solution Approach 2:
The drive shaft (4) serves multiple purposes: it transmits rotation from the motor, provides axial adjustment capability, and supports the cutter head. This multi-functionality eliminates the need for a hollow-shaft motor and separate motion rod, achieving a more compact design.
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 achieves high rigidity and energy efficiency in the axial adjustment of the cutter head, maintaining a compact design and reducing energy losses associated with prior art designs.
Implementation Method 1
the spindle drive stage (7) can be configured as a planetary thread drive, with planetary thread rollers being provided between the tube nut (8) and the spindle element (9), which convert a rotational movement of the tube nut (8) into an axial movement of the spindle element (9)
Implementation Method 2
the spindle drive stage (7) can also be configured as a screw thread drive in which no planets are provided between the tube nut (8) and the spindle element (9), but instead an internal thread of the tube nut (8) is in screw engagement with an external thread of the spindle element (9)
Implementation Method 3
a servomotor (10) is provided for rotationally driving the tube nut (8) of the spindle drive stage (7)
Implementation Method 4
the bearing assembly (16) may comprise one or more rolling bearings, for example in the form of a tapered roller bearing pair or a radial/axial bearing pair
Implementation Method 5
a belt stage (18) can be provided, the belt (36) of which can drive a drive pinion (19), which can be mounted on an end face of the tube nut (8) and connected thereto in a rotationally-fixed manner
Data Source
AI summary
A pelletizer with a rotatably drivable cutter head for dividing material strands output from a die plate into pellets, the cutter head being drivingly connected to a drive motor via a drive shaft, and with a feed device for axial adjustment of the cutter head relative to the die plate in the direction of the cutter head axis of rotation. A spindle element of a spindle drive stage of the feed device is configured as a spindle sleeve which is axially firmly seated on the rotating drive shaft between the drive motor and the cutter head. The drive shaft is connected to the cutter head in an axially-fixed and rotationally-fixed manner and transmits the axial movement of the spindle sleeve to the cutter head.