Servomotor Ladle Control for Molten Metal Flow Rate

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Solution Overview

Problem

Conventional automatic pouring systems in foundries face challenges in maintaining consistent molten metal flow patterns due to inappropriate tilting speeds and environmental disturbances, leading to inferior casting quality and inclusion of impurities like dust and slag.

Innovation Solution

A method that uses a computer-controlled servomotor system, incorporating a mathematical model, extended Kalman filter, and gain-scheduled PI controller to estimate and regulate the flow rate of molten metal, ensuring accurate pouring by compensating for errors caused by the ladle's center of gravity movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a teaching-and-playback method is used to control the ladle tilting speed, then the system can record and reproduce pouring processes, but the system cannot adapt to inappropriate tilting speeds or changes in pouring conditions

Engineering Contradiction:

Improveautomatic pouring controlVSAvoidadaptability to pouring condition changes

Core Design Contradiction:

Extent of automationVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback control system that uses a load cell to detect the weight of the ladle in real-time. The control device receives weight change signals and automatically adjusts the tilting speed of the ladle based on the detected weight, enabling the system to adapt to changing pouring conditions without manual intervention.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from a static teaching-and-playback method to a dynamic control system that continuously adjusts tilting speed based on real-time weight detection. The control device modifies the tilting speed dynamically according to the actual pouring conditions, making the system adaptable to various scenarios.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If the ladle tilting speed is not properly controlled, then the pouring process is simple, but the castings become inferior in quality and impurities are disposed in the mold

Engineering Contradiction:

Improvecasting qualityVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The load cell provides continuous feedback on the ladle weight, allowing the control device to precisely regulate the tilting speed. This feedback mechanism ensures that the molten metal flows at the optimal rate, preventing impurities from entering the mold while maintaining high casting quality.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces manual mechanical control of the ladle tilting with an automated electro-mechanical system. The load cell and control device substitute for human operators, providing precise and consistent tilting speed control that improves casting quality while reducing the complexity of manual operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the center of gravity of the ladle moves during tilting, then the pouring process is simple, but measurement errors occur in weight detection

Engineering Contradiction:

Improveweight measurement accuracyVSAvoidladle tilting operation

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent positions the load cell at the center of gravity of the ladle assembly. This placement ensures that when the ladle tilts, the center of gravity remains aligned with the load cell, preventing measurement errors caused by shifting weight distribution. The counterbalancing effect maintains accurate weight detection throughout the pouring process.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

By positioning the load cell at the center of gravity, the system creates an equipotential condition where the weight measurement remains accurate regardless of the ladle's tilting angle. This ensures that the gravitational force acts uniformly through the measurement point, eliminating errors.

Inventive Principle:

Principle #12Equipotentiality

Data Source

PatentUS8202472B2Method for controlling a process for automatically pouring molten metal, a system for controlling a servomotor of an automatic pouring apparatus, and a medium for recording programs for controlling a tilting of a ladle

Publication Date: 2012.06.19 SINTOKOGIO LTD

AI summary

A method for controlling a ladle to pour molten metal into a mold. The method comprises producing a mathematical model describing a relationship between a measured electrical voltage supplied to a servomotor for tilting the ladle and a flow rate of the molten metal flowing out of the ladle when the ladle is tilted; solving an inverse problem of the mathematical model; estimating the flow rate of the molten metal using a state observer having an exponential damping that uses an extended Kalman filter, based on the measured electrical voltage and a weight of the molten metal poured into the mold; processing the flow rate of the molten metal and a target flow rate of the molten metal with a gain-scheduled PI controller; obtaining a target electrical voltage to be supplied to the servomotor; and controlling the servomotor based on the target electrical voltage.