Embed Size (px)
Citation preview
An automated optical method for measuring and characterizing face
check development in maple veneered panels
Mike BurnardLech Muszynski, Ph.D.Scott Leavengood, Ph.D.Lisa Ganio, Ph.D.
Oregon State University
Outline
• Introduction
• Background & Motivation
• Objective
• System Requirements & Components
• Future work
Background: maple panels
• Decorative
• Used indoors
• Can be expensive
• A composite with face, core, & back
Background: panel manufacturing
oakwoodveneer.com, inhabitat.com
Decorative maple panel manufacturing involves many factors including: veneer, adhesives, cores & pressing
Background: checking
Checking is caused by the differential drying rate between the face and the core of the panel
Background: panel checking
Many factors have been identified as possibly contributing to checking:
• Veneer properties
• Panel construction
• Service conditions
Background: checking factors
• Veneer thickness
• Lathe check orientation
• Sliced/peeled
• Log prep method
• Source region
• Adhesive type
• Core type
• Pressing cycles
• Cross-band lathe check orientation
• others…
Background: panel checking
Standards allow 2 small, mended checks in specific regions:
.8mm wide, 72mm long on edges
Motivation
• Checking is an expensive problem for manufacturers and the industry
• Manufacturing maple veneer plywood panels is complex and involves many factors
Motivation
• Large studies testing many factors have been impractical because of the laborious manual inspection methods used in the past
• An experimental method to efficiently measure and quantify checks as they occur
Background: optical method
Kang et al (2007) developed a non-contact optical method to detect checks as they occur. The method lends itself to automation.
Background: optical method
Uses two cameras trained on an object to monitor how it changes over time in three dimensions.
Negative Positive
110 min
185 min
Strain, εxKang et al, 2007
Objective
Develop an efficient procedure in which the optical method can be applied to measure checks as they develop in multiple panels simultaneously to test an unprecedented number of factors
Checking factors
• Veneer thickness
• Lathe check orientation
• Sliced/peeled
• Log prep method
• Source region
• Adhesive type
• Core type
• Pressing cycles
• Cross-band lathe check orientation
• others…
• Modular optical unit with sufficient resolution to detect critical checks
• Climate chamber capable of maintaining a low equilibrium moisture content to accelerate check formation
System Components
Requirements: critical checks
Determined critical checks are those with a minimum width of:
~0.2 mm
Requirements: optical unit
Detecting critical checks in multiple panels simultaneously is imperative.
Requirements: optical unit
Utilizing multiple cameras allows more panels to be examined simultaneously.
Test single vs. dual cameras & industrial vs. consumer cameras
Requirements: optical unit
Consumer cameras proved unreliable and not easily automated.
Both single and dual industrial cameras proved sufficient to detect critical checks.
-0.010
-0.005
0.000
0.005
0.010
0 1 2 3 4 5 6 7
Stra
in
Image
Strain, εxx
50mm Lens Single Camera12mm Lens Single Camera50mm Lenses Dual Camera
Requirements: climate chamber
Temperature and relative humidity tests revealed an average equilibrium moisture content of: 8%
• Size
• Dedicated
• Climate conditions
Requirements: climate chamber
Introducing a space heater with a fan reduced the equilibrium moisture content to:
6%
Future Work
• Purchase and test lower-resolution industrial cameras
• Build modular test chamber
Work in progress…
Thank you.
Questions? Comments?
Temperature (°C), Relative Humidity (%) & Equilibrium Moisture Content (%)
2
3
4
5
6
7
8
9
20
25
30
35
40
45
1
16
51
EMC
(%
)
Tem
pe
ratu
re (
°C),
Re
lati
ve H
um
idit
y (%
)
Time intervals (x5 minutes)
RH, % Temp, C
EMC, %
1070
1075
1080
1085
1090
1095
1100
0 50 100 150 200 250 300
We
igh
t (g
)
Time (minutes)
Panel weight loss
21C, 41%RH 31C, 27%RH
References available upon request
