Grinding Device Acoustic Fill Level Control

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Solution Overview

Problem

Existing grinding devices for rolling elements, such as balls, face challenges in achieving high process reliability with minimal fluctuations in product parameters under series production conditions, particularly in determining the optimal degree of filling which affects material removal and forces acting on the workpieces.

Innovation Solution

A grinding device equipped with a grinding wheel arrangement and an evaluation system for individual acoustic detection of rolling bodies, determining the degree of filling by analyzing time intervals between acoustic signals, average dwell time, and geometric features of the grinding device and workpieces, using a formula that calculates the filling level based on these parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the fill level of the grinding device is increased to improve productivity, then more rolling elements can be ground simultaneously, but the forces acting on the workpieces become unbalanced and material removal uniformity deteriorates

Engineering Contradiction:
Improvenumber of rolling elements ground simultaneouslyVSAvoiduniformity of material removal
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs acoustic sensors to detect the discharge of ground rolling elements and uses this feedback to continuously monitor and control the fill level. By measuring the acoustic signals from discharged elements and comparing them against target values, the system dynamically adjusts the feed rate to maintain optimal fill level, ensuring uniform material removal while maximizing productivity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes the operational parameters, specifically the fill level and feed rate, based on real-time acoustic monitoring. By adjusting these parameters to maintain an optimal range (e.g., 30-70% fill level), the system achieves both high productivity and uniform material removal, resolving the contradiction between processing capacity and quality consistency.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If acoustic sensors are introduced to detect rolling elements and determine fill level, then process control and manufacturing precision are improved, but device complexity increases

Engineering Contradiction:
Improvecontrol of fill level and material removalVSAvoidnumber of sensors and evaluation components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The acoustic sensor system is designed to automatically monitor and control the grinding process without requiring external intervention. The evaluation unit continuously processes acoustic signals, determines fill level, and adjusts operational parameters autonomously, making the complex system self-regulating and reducing the need for additional control infrastructure.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical fill level measurement systems with acoustic sensing technology. Instead of using mechanical sensors, switches, or direct physical measurement devices, the system uses acoustic field-based detection to monitor rolling element discharge and infer fill level, thereby achieving precise control with a less intrusive and potentially simpler implementation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If the fill level is set to a defined value below 100% to ensure uniform material removal, then manufacturing precision is improved, but productivity decreases due to reduced capacity

Engineering Contradiction:
Improveuniformity of product parametersVSAvoidoutput per unit time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system transitions from a static fill level setting to a dynamic control approach. The fill level is continuously adjusted based on real-time acoustic monitoring of rolling element discharge. This dynamic adaptation allows the system to maintain optimal precision while maximizing throughput by responding to actual process conditions rather than operating at a fixed, conservative fill level.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By implementing feedback control through acoustic sensing, the system can operate at higher fill levels while maintaining precision. The continuous monitoring of discharged elements provides real-time information that allows the system to compensate for variations in fill level, enabling higher productivity without sacrificing the uniformity of material removal that would otherwise require lower fill levels.

Inventive Principle:
Principle #23Feedback

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 approach allows for precise control of the grinding process, ensuring even material removal and consistent product parameters by accurately determining and setting the degree of filling, thereby enhancing process reliability and reducing fluctuations.

Implementation Method 1

an acoustic sensor (13) assigned to a collecting body (12), with the acoustic sensor (13) being designed for the individual acoustic detection of rolling elements (2) discharged from the rolling element outlet (9) as the rolling elements (2) fall onto the collecting body (12)

Methodology Applied
Scientific EffectAcoustic detection: Acoustic Emission

Data Source

PatentEP4161730B1Grinding device for rolling bodies and method for determining the degree of filling of a grinding device
Publication Date: 2024.05.29 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP4161730B1 patent drawingFigure 1
  • EP4161730B1 patent drawingFigure 2~3
  • EP4161730B1 patent drawing

AI summary

A grinding device (1) for rolling bodies (2), in particular balls, comprises at least one grinding wheel (3, 4), which is designed for grinding rolling bodies (2) which are guided in at least one track (10) of the grinding wheel (3, 4). Also provided is an evaluation system (14), which is designed for acoustically detecting individual rolling bodies (2) which are guided by way of the track (10) and, thereby, for determining the degree of filling (FG) of the track (10).