Green Lumber Sorting by Moisture Density Ratio

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Solution Overview

Problem

Current lumber drying processes in kilns are inefficient and result in inconsistent moisture content levels across batches, leading to under-dried or over-dried lumber, which affects quality and increases production costs.

Innovation Solution

Implementing a sorting system that groups green lumber based on a moisture content ratio, combining weight or density with moisture content measurements to predict and optimize drying times, allowing for more precise control over the drying process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If green lumber is dried in a kiln using traditional batch processes, then large amounts of lumber can be processed efficiently, but the moisture content levels become inconsistent across batches, resulting in under-dried or over-dried lumber

Engineering Contradiction:
Improvedrying throughputVSAvoidmoisture content uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention segments green lumber into different species groups (softwood, hardwood, mixed) before drying. By dividing the lumber into species-specific batches and drying each group separately with optimized parameters, the system maintains high productivity while achieving consistent moisture content levels within each species group, thereby resolving the contradiction between batch processing efficiency and moisture uniformity.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If all green lumber is dried using the same kiln process, then production costs are reduced through simplified operations, but quality varies significantly due to different species having different drying requirements

Engineering Contradiction:
Improvedrying process simplicityVSAvoidlumber quality consistency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention applies local quality by tailoring drying parameters (temperature, humidity, air flow) to each lumber species group rather than using a universal process. Softwood, hardwood, and mixed species each receive customized drying schedules matched to their specific characteristics, ensuring consistent quality outcomes while maintaining operational simplicity through automated species identification and process selection.

Inventive Principle:
Principle #3Local quality

3Device complexity

If lumber is not sorted by species before drying, then the drying process is simpler and faster to implement, but the resulting lumber has inconsistent moisture content affecting quality and increasing production costs

Engineering Contradiction:
Improvesorting system complexityVSAvoidmoisture content control
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The invention changes the parameter of species classification by using automated optical sensors and image recognition to identify lumber species based on color, grain patterns, and other visual characteristics. This non-invasive sorting method adds minimal complexity to the drying system while enabling precise moisture content control through species-specific drying profiles, thereby improving manufacturing precision without significantly increasing device complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9470455B2Sorting green lumber
Publication Date: 2016.10.18 WEYERHAEUSER NR CO
  • US9470455B2 patent drawing
  • US9470455B2 patent drawing
  • US9470455B2 patent drawing

AI summary

A method of sorting green lumber is based on a ratio of moisture content to either weight or density. The moisture content of each piece of green lumber is measured, and the weight or density of the green lumber is measure. One more thresholds of moisture content to weight or density ratios are used to divide the green lumber into groups. Such a sort tends to produce groups of green lumber that require similar kiln drying schedules.