Fixed Motor Roller Mill Drive with Homokinetic Coupling
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Solution Overview
Problem
Roller mills with large throughputs face high investment costs and unsatisfactory availability due to the substantial weight and vibrations of drive mechanisms, leading to increased stress on bearings and undesirable vibrations in the system.
Innovation Solution
A roller mill design featuring a fixed motor-driven grinding roller with a coupling arranged in the pivot lever axis or its extension, which compensates for pivot movement to ensure homokinetic transmission of rotational movement, minimizing vibrations and allowing the use of cheaper, maintenance-free components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the complete drive with motor and gearing mechanism is provided on the pivot lever, then the grinding roller can be driven directly, but the substantial weight of the drive increases demands on the bearing and causes powerful vibrations
Solution Approach 1:
The drive mechanism is extracted from the pivot lever and positioned on the grinding table instead. This separates the heavy drive components from the moving pivot lever, reducing the weight that the pivot bearing must support while maintaining direct drive capability to the grinding roller.
Solution Approach 2:
The drive is repositioned from a vertical arrangement on the pivot lever to a horizontal arrangement on the grinding table surface. This dimensional change allows the drive to be accessible and maintain drive function while removing it from the critical pivot bearing load path.
2Device complexity
If a cardan shaft is used to transmit drive power to the pivot lever, then the motor can be fixed in position, but angular compensation in the articulations causes displacement angles and non-homokinetic transmission resulting in vibrations
Solution Approach 1:
The cardan shaft and intermediate shaft are removed from the system. Instead, a direct coupling is used between the motor and the pivot lever gearing, eliminating the non-homokinetic transmission and associated vibrations while keeping the motor fixed in position on the grinding table.
Solution Approach 2:
A coupling device is introduced as an intermediary between the motor shaft and the pivot lever gearing. This coupling provides the necessary connection while maintaining homokinetic transmission, replacing the problematic cardan shaft arrangement.
3Volume of moving object
If gearing mechanisms are arranged on the pivot lever or in the region of the grinding roller, then the drive can be compact, but the substantial weight and complexity increase bearing demands and maintenance requirements
Solution Approach 1:
The gearing mechanism is merged with the pivot lever assembly, where the pivot lever itself serves as part of the gear train. This integration maintains a compact arrangement while simplifying the overall structure by reducing the number of separate components and connections required.
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 design minimizes system vibrations and reduces the need for costly and complex compensation mechanisms, enabling the use of standard motors and ensuring a long service life with a torsionally rigid coupling, thus improving the operational efficiency and reducing maintenance costs.
Implementation Method 1
A roller mill (1) having a rotatable grinding table (2) and at least one grinding roller (3) which is retained rotatably on a pivot lever (2) and which is in rolling engagement with the grinding table (2), with the pivot lever (2) being arranged for pivoting about a pivot lever axis (6). Associated with the grinding roller (3) is a drive train which drives the grinding roller (3) with a fixed motor (4). The drive train has a coupling (12) which is arranged in the pivot lever axis (6) or the extension thereof and which compensates for the pivot movement of the pivot lever (2).
Data Source
AI summary
A roller mill includes a rotatable grinding table, at least one grinding roller that is retained rotatably on a pivot lever and is in rolling engagement with the grinding table, with the pivot lever being arranged for pivoting about a pivot lever axis, and a drive train associated with the grinding roller in order to drive the grinding roller with a fixed motor.