Motor Current Monitoring for Thread Forming Fault Detection

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Solution Overview

Problem

Existing methods for monitoring and ensuring reliable thread formation in machining processes are complex, costly, and often fail to detect manufacturing errors or tool faults in a timely manner, leading to defective parts and high reworking costs.

Innovation Solution

A method using torque monitoring based on current consumption of electric motors, where a software-implemented solution records and analyzes torque data to establish permissible limits, triggering a stop if deviations exceed predefined thresholds, and integrating this with existing control components to detect and prevent faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex monitoring systems are installed to detect manufacturing errors and tool faults, then detection capability is improved, but device complexity and cost increase significantly

Engineering Contradiction:
Improvedetection capabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the monitoring function from complex mechanical monitoring systems and implements it through software-based torque analysis. By taking out the essential monitoring capability and implementing it through current consumption analysis of the electric motor, the system achieves reliable fault detection without the complexity of additional mechanical sensors and monitoring hardware.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces mechanical monitoring systems with an electrical/software-based solution. Instead of using mechanical sensors and complex monitoring hardware to detect tool faults and manufacturing errors, the system uses electric motor current consumption data to infer torque variations and detect abnormalities through software analysis.

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

2Reliability

If existing complex monitoring systems are used, then fault detection is possible, but adjustment and programming effort and cost increase

Engineering Contradiction:
Improvefault detectionVSAvoidadjustment and programming effort
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The monitoring system uses the electric motor's own current consumption data as the monitoring signal. By analyzing the motor's inherent electrical parameters during operation, the system achieves fault detection without requiring external sensors or complex programming, making the system easy to implement and adjust.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent makes the electric motor serve multiple functions: it provides both the driving torque for the thread-forming tool and simultaneously serves as the monitoring sensor through its current consumption characteristics. This multi-functionality eliminates the need for separate monitoring hardware and reduces programming complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If traditional monitoring approaches are used, then some faults may be detected, but detection timing is delayed leading to defective parts and reworking costs

Engineering Contradiction:
Improvefault detection timingVSAvoiddetection delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system continuously monitors electric motor current consumption throughout the entire machining process. This continuous electrical measurement provides real-time torque information, enabling immediate detection of abnormalities such as tool breakage or manufacturing errors without the detection delays associated with periodic mechanical monitoring.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system establishes a feedback loop where electric motor current consumption is continuously measured and analyzed to detect torque variations. This real-time feedback mechanism enables immediate identification of faults and timely intervention, preventing the production of defective parts and reducing reworking costs.

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 enhances process reliability and cost-effectiveness by accurately detecting torque deviations, preventing tool damage, and ensuring consistent thread formation, thereby reducing reworking costs and improving part quality.

Implementation Method 1

a rotatingly drivable machining unit (20) which can be driven by an electric motor (10), in particular a servo motor

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a controller (100) with a detection module (30) which detects the current consumption (Iactual) (actual values) of the electric motor (10), which corresponds to torque generation

Methodology Applied
Scientific EffectElectrical measurement: Ohmmeter

Data Source

PatentEP3165980B1Process monitoring
Publication Date: 2020.01.01 FIBRO GMBH
  • EP3165980B1 patent drawingFigure 1~2
  • EP3165980B1 patent drawingFigure 3
  • EP3165980B1 patent drawing

AI summary

The invention relates to a method for process monitoring of a rotating machining unit (20) driven by an electric motor (10) comprising the following steps: detecting the current consumption (IIst) corresponding to torque generation (actual values) of the electric motor (10) by means of at least one detection module (30); comparing the detected actual value (IIst) with stored target values ​​(Imin, Imax) of a target value range (Isoll); determining whether the actual value (IIst) of the current consumption is a permissible value from the target value range (Isoll); and outputting a signal (S) when a deviation of the actual value (IIst) is detected in order to thereby detect a torque deviation of the rotating machining tool (20).