Piston Position Measurement Using Laser Optical Detection

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Solution Overview

Problem

Current injection molding machines face challenges in accurately measuring the position of the piston, which affects the precision and reliability of injecting resin into molds, particularly due to limitations in existing position sensing technologies.

Innovation Solution

The proposed solution involves an injection unit with a cylinder casing and a piston having a measurement detection feature, where a probe communicates with the piston to measure its translation between advanced and retracted positions, utilizing a gear system or distance sensor to accurately determine the piston's position, and includes a pressure chamber for fluid-driven piston movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional position sensor is used to measure piston position, then the measurement system is simple to implement, but the measurement precision is insufficient for accurate injection control

Engineering Contradiction:

Improvepiston position measurement precisionVSAvoidposition measurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical position sensors with a laser-based optical measurement system. A laser beam is directed through the piston onto a scale attached to the piston, and the position is determined by measuring the laser beam's position on the scale using photodetectors. This substitution of mechanical sensing with optical measurement achieves high precision piston position measurement without the limitations of conventional sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the piston position is not accurately measured, then the injection process is simpler to control, but the injection precision and reliability deteriorate

Engineering Contradiction:

Improveinjection precisionVSAvoidposition measurement system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a laser-based optical measurement system that provides precise piston position data for controlling the injection process. The system uses a laser beam, a scale attached to the piston, and photodetectors to accurately determine piston position, enabling precise control of resin injection into molds.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs feedback control by continuously measuring piston position with the laser measurement system and using this information to control the injection process. The measured position data is fed back to the control system, which adjusts the injection parameters to achieve precise and reliable resin injection, improving both injection precision and process repeatability.

Inventive Principle:

Principle #23Feedback

3Reliability

If existing position sensing technologies are used, then the system is easier to implement, but the reliability of resin injection into molds is compromised

Engineering Contradiction:

Improveresin injection reliabilityVSAvoidposition measurement system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces unreliable conventional position sensors with a laser-based optical measurement system that provides accurate and reliable piston position data throughout the injection process. The optical system measures the position of the piston by tracking the laser beam's position on a scale, ensuring consistent and reliable resin injection into molds.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback control using the laser measurement system to continuously monitor piston position and adjust injection parameters accordingly. This feedback mechanism ensures reliable resin injection by maintaining precise control over the injection process based on actual piston position data.

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 solution enables precise and reliable measurement of the piston's position, ensuring consistent and accurate injection of resin into molds, improving the efficiency and repeatability of the injection molding process.

Implementation Method 1

a probe fixed relative to the cylinder casing, the probe communicating with the measurement detection feature when the piston is in and moving between the advanced and retracted positions to measure the translation of the piston

Methodology Applied

Scientific EffectPosition detection:

Implementation Method 2

The pressure chamber may contain a fluid to move the piston towards one of the advanced position and the retracted position when pressurized

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentUS8932040B2Injection unit with a piston position measurement system

Publication Date: 2015.01.13 MILACRON MARKETING CO LLC

AI summary

An injection unit includes a cylinder casing comprising an inner cylindrical surface extending along an axis, and a piston housed in the casing and translatable along the axis between an advanced and a retracted position. The piston includes a piston radial surface in facing relation to the inner cylindrical surface, and the piston radial surface has a measurement detection feature. A probe is fixed relative to the cylinder casing, the probe communicating with the measurement detection feature when the piston is in and moving between the advanced and retracted positions to measure the translation of the piston.