Spark Plug Crimping Jig Control via Overshoot Compensation

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Solution Overview

Problem

The crimping process in spark plug production, particularly for small-diameter spark plugs, faces challenges in achieving precise buckling of the to-be-buckled portion, affecting the fixation and ignition performance due to variations in the moving distance and load of the crimping jig, leading to deviations from the target buckling amount.

Innovation Solution

Adjusting the preset contact load and distance by accounting for overshoot amounts through measured or estimated values from past data, allowing for precise control of the crimping jig's movement to match the target moving distance, thereby reducing deviations and ensuring consistent buckling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the preset distance of the crimping jig is increased to achieve target buckling amount, then the buckling amount is improved, but the moving distance deviation increases due to overshoot

Engineering Contradiction:
Improvebuckling amountVSAvoidmoving distance deviation
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The control apparatus measures the actual moving distance of the crimping jig and feeds back this information to adjust the preset distance. The preset distance is dynamically modified based on the difference between actual and target moving distances, creating a closed-loop control system that eliminates overshoot and achieves precise buckling control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The preset distance parameter is adjusted based on measured overshoot amounts. By changing the preset distance parameter dynamically rather than using a fixed value, the system compensates for overshoot and achieves the target moving distance and buckling amount.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the preset contact load is increased to ensure proper fixation, then the fixation state is improved, but the moving distance control precision deteriorates due to load-induced overshoot

Engineering Contradiction:
Improvefixation stateVSAvoidmoving distance control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The control apparatus measures the actual contact load and feeds back this information to adjust the preset contact load. The preset contact load is dynamically modified based on the difference between actual and target contact loads, creating a closed-loop control system that maintains proper fixation while achieving precise moving distance control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The preset contact load parameter is adjusted based on measured overshoot amounts. By changing the preset contact load parameter dynamically rather than using a fixed value, the system compensates for load-induced overshoot and achieves both proper fixation and precise moving distance control.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the crimping jig moves faster to increase productivity, then the production speed is improved, but the moving distance accuracy deteriorates due to increased overshoot

Engineering Contradiction:
Improveproduction speedVSAvoidmoving distance accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The control apparatus dynamically adjusts the preset distance based on the actual moving speed of the crimping jig. When the jig moves faster, the system automatically modifies the preset distance to compensate for speed-induced overshoot, maintaining moving distance accuracy across different production speeds.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The preset distance parameter is adjusted based on the relationship between moving speed and overshoot amount. By changing the preset distance parameter according to actual speed rather than using a fixed value, the system maintains precision despite variations in production speed.

Inventive Principle:
Principle #35Parameter changes

4Length of moving object

If the wall thickness of the to-be-crimped portion is reduced for small-diameter spark plugs, then the spark plug size is reduced, but the buckling control difficulty increases due to sensitivity to moving distance variations

Engineering Contradiction:
Improvespark plug diameterVSAvoidbuckling control
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The control apparatus measures the actual moving distance and feeds back this information to adjust the preset distance in real-time. This closed-loop control compensates for the high sensitivity of thin-walled structures to moving distance variations, enabling precise buckling control in small-diameter spark plugs.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The preset distance parameter is dynamically adjusted based on measured overshoot amounts and actual moving conditions. By changing the preset distance parameter rather than using a fixed value, the system compensates for the increased sensitivity of thin-walled structures and achieves consistent buckling control.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3096421B1Method for manufacturing spark plug
Publication Date: 2019.09.11 NITERRA CO LTD
  • EP3096421B1 patent drawingFigure 1
  • EP3096421B1 patent drawingFigure 2
  • EP3096421B1 patent drawingFigure 3

AI summary

The moving distance of a crimping jig in a crimping-pressing step is rendered close to a target moving distance set in advance. The crimping-pressing step includes (1) a step of bringing the crimping jig into contact with a to-be-crimped portion and moving the crimping jig forward such that a load acting on the crimping jig reaches a preset contact load, and (2) a buckling step of further moving the crimping jig forward by a preset distance and then stopping the crimping jig. The difference between the target moving distance of the crimping jig and its actual moving distance is reduced by adjusting at least one of the preset contact load and the preset distance on the basis of at least one of a first overshoot amount in the step (1) and a second overshoot amount in the step (2).