Eccentric Press Stroke Control via Rotary Encoder

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Solution Overview

Problem

Adjusting the stroke length of an eccentric press is a tedious, error-prone, and accident-risky process that relies solely on manual operation of the machine operator, as it requires adjusting mechanical cam switching mechanisms, which is time-consuming and lacks supporting tools for functional safety.

Innovation Solution

A control device and method that utilize a rotary encoder to electronically generate switching signals and automatically track switching points, replacing the mechanical cam switch mechanism with a combination of safe sensors and control logic, allowing for automatic adjustment of stroke length without manual intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical cam switching mechanism is used to generate switching signals, then the press can be controlled through mechanical means, but the adjustment of switching points becomes tedious, error-prone, and time-consuming

Engineering Contradiction:
Improveswitching point accuracyVSAvoidadjustment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical cam switching mechanism with an electronic sensor system. Sensors detect the actual positions of the eccentric shaft and generate switching signals electronically, eliminating the need for mechanical cam adjustment. This substitution resolves the contradiction by providing both high reliability through precise electronic detection and time efficiency through automatic adaptation.

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

Solution Approach 2:

The control system automatically adapts to stroke length changes by detecting the new positions of switching points through sensors and recalibrating the switching signals without manual intervention. The system serves itself by automatically compensating for stroke adjustments, eliminating the tedious manual adjustment process while maintaining high accuracy.

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If the stroke length is adjusted by rotating the eccentric shaft, then the press can adapt to different work requirements, but the positions of switching points change and require manual readjustment

Engineering Contradiction:
Improvestroke length adjustmentVSAvoidswitching point adjustment
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent implements a feedback mechanism where sensors continuously monitor the positions of the eccentric shaft and provide this information to the control system. When the stroke length is adjusted, the feedback from the sensors enables the control system to automatically recalculate and adjust the switching points, maintaining ease of operation while providing full adaptability for different stroke lengths.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system automatically tracks and adjusts switching point positions in response to stroke length changes without requiring operator intervention. The self-service capability resolves the contradiction by maintaining ease of operation (no manual adjustment needed) while enabling full adaptability (automatic adaptation to any stroke length).

Inventive Principle:
Principle #25Self-service

3Device complexity

If manual adjustment of cam switches is required after stroke adjustment, then the system can be simple in structure, but the procedure is prone to errors and involves accident risks

Engineering Contradiction:
Improvecontrol system structureVSAvoidoperation safety
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces the mechanical cam switching mechanism with an electronic sensor-based system that automatically generates switching signals. This substitution increases device complexity slightly through the addition of sensors and electronic control, but dramatically improves operation safety by eliminating manual intervention in the adjustment process, thus resolving the contradiction between simplicity and safety.

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

4Device complexity

If the cam switch mechanism is difficult to access after climbing ladders or removing housing parts, then the mechanical structure can be compact, but the ease of maintenance and adjustment deteriorates

Engineering Contradiction:
Improvemechanical structure compactnessVSAvoidswitching mechanism accessibility
Core Design Contradiction:
Device complexityVSEase of repair

Solution Approach 1:

The patent replaces the mechanically complex cam switching mechanism with electronic sensors that can be positioned in more accessible locations. This substitution maintains the compactness of the overall mechanical structure while dramatically improving accessibility for maintenance and adjustment, as electronic components are easier to access and service than mechanical cam mechanisms located in hard-to-reach areas.

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

Data Source

PatentEP3466662B1Secure control device and method for adjusting the stroke length of an eccentric press
Publication Date: 2020.02.26 SICK AG
  • EP3466662B1 patent drawingFigure 1~2
  • EP3466662B1 patent drawingFigure 3
  • EP3466662B1 patent drawingFigure 4~5

AI summary

A safe control device (10) for adjusting the stroke length of an eccentric press (100) is described, wherein the eccentric press (100) has a ram (102) driven via a connecting rod (104) by an eccentric system (106) comprising an eccentric shaft (108) and an eccentric bushing (114) which can be detached from each other and then rotated relative to each other to adjust the stroke length, wherein the control device (10) has an encoder (12) for determining the rotational position of the eccentric shaft (108) and a control logic (10) to generate a first switching signal at at least one first rotational position (BDC, TDC). The control logic (10) is configured to automatically adjust the first rotational position (BDC, TDC) when the stroke length is changed.