Cementitious Board Hydration Monitoring via Compression Force

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Solution Overview

Problem

Current methods for monitoring the set of cementitious slurry during cementitious board manufacturing are inefficient, relying on manual 'thumb tests' and temperature rise measurements, which are subjective and prone to errors, and do not provide continuous, accurate data on hydration rates.

Innovation Solution

A system comprising a compression member, actuator assembly, and force gauge is used to measure the resistance force of the cementitious board, correlating it to the degree of slurry set, allowing for automatic and continuous monitoring of percent hydration and hardness, and providing data for process control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual thumb tests are used to monitor slurry set, then operator experience can guide decisions, but measurement precision and reliability are poor due to subjectivity

Engineering Contradiction:
Improveslurry set measurement precisionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical thumb tests with an automated mechanical measurement system. A compression member with a force gauge automatically applies a standardized compressive force to the cementitious board and measures the resistance force, eliminating operator subjectivity while maintaining mechanical measurement principles. This resolves the contradiction by providing precise, objective measurements without requiring complex electronic or optical systems.

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

2Measurement precision

If temperature rise measurements are used to monitor hydration, then continuous data can be obtained, but measurement precision is reduced due to ambient temperature influences and other interfering factors

Engineering Contradiction:
Improvehydration rate measurement precisionVSAvoidproduction speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces thermal measurement methods with a mechanical compression measurement system. By measuring the resistance force of the cementitious board to applied compression, the system directly assesses hydration progress without being influenced by ambient temperature fluctuations or thermal interference. This provides precise hydration monitoring that does not compromise production speed.

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

3Productivity

If automated measurement systems are implemented, then productivity and consistency improve, but device complexity increases

Engineering Contradiction:
Improveproduction speedVSAvoidmeasurement system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements automation through a mechanically-simple system consisting of a compression member, actuator assembly, and force gauge. The actuator automatically positions the compression member against the moving cementitious board, and the force gauge records resistance force. This mechanical automation approach improves productivity and consistency while avoiding the complexity of electronic sensors, optical systems, or complex control mechanisms.

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

4Reliability

If periodic manual testing is performed, then operator safety is maintained, but measurement precision and reliability deteriorate due to inconsistent timing and operator variability

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidmeasurement automation level
Core Design Contradiction:
ReliabilityVSExtent of automation

Solution Approach 1:

The patent replaces periodic manual testing with continuous automated mechanical measurement. The system automatically measures the resistance force of each segment of cementitious board as it passes through the measurement position, ensuring consistent timing and eliminating operator variability. The mechanical system maintains reliability through standardized, repeatable measurement procedures while achieving full automation.

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

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 system enables precise, automated measurement of slurry set characteristics, reducing operator intervention and improving the consistency and quality of cementitious board production by providing real-time data on hydration rates and hardness.

Implementation Method 1

A compression member is disposed over the conveyor at a measurement position in downstream relationship to the forming station along the machine direction

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

A force gauge is associated with the compression member such that the force gauge is configured to measure a resistance force against the compression member

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

The calcined gypsum reacts with the water in the wallboard preform to form a matrix of crystalline hydrated gypsum or calcium sulfate dihydrate and sets as a conveyor moves the wallboard preform down the manufacturing line

Methodology Applied
Scientific EffectHydration: Mineral Hydration

Implementation Method 4

The actuator assembly is configured to selectively move the compression member over a range of travel along a normal axis between a stowed position and an engaged position

Methodology Applied
Scientific EffectMechanical actuation: Mechanical Force

Data Source

PatentEP3471937B1System and method for manufacturing cementitious boards with on-line slurry set measurement
Publication Date: 2021.08.04 UNITED STATES GYPSUM CO
  • EP3471937B1 patent drawingFigure 1
  • EP3471937B1 patent drawingFigure 2
  • EP3471937B1 patent drawingFigure 3

AI summary

Embodiments of a system and a method for measuring cementitious board (25) during its continuous manufacture can be used online in a continuous manufacturing process to effectively determine the degree to which cementitious slurry has set (e.g., expressed as percent hydration) at a predetermined location, such as, near a cutting station, for example. A compression assembly (100) can be used to compressively engage the cementitious board (25) in a controlled manner as it passes by the compression member (120) along the conveyor (32) between the forming station (30) and the cutting station (38). A force gauge (124) can be associated with the compression member (120) to measure the resistance force exerted by the cementitious board (25) in response to being compressed by the compression member (120). The resistance force can be correlated to a set characteristic of the cementitious board (25), such as a numerical value of percent hydration of the cementitious slurry of that particular portion of the cementitious board (25).