Method and apparatus for detecting and characterizing splits in logs

• US 20020043108A1
• Filed: 03/07/2001
• Published: 04/18/2002
• Est. Priority Date: 04/16/1998
• Status: Active Grant

• Current Assignee: USNR, LLC
• Original Assignee: US Natural Resources Incorporated (U.S. Natural Resources)
• Inventors: Ross, Robert J., Schafer, Mark E.
• Granted Patent: US 6,467,352 B2
• Time in Patent Office: Days
• US Class Current: 73/632
• CPC Class Codes: G01N 2291/0238 Wood
• CPC Class Codes: G01N 2291/0421 Longitudinal waves
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 2291/103 one emitter, two or more receivers
• CPC Class Codes: G01N 2291/105 two or more emitters, two or more receivers
• CPC Class Codes: G01N 2291/2634 cylindrical from outside
• CPC Class Codes: G01N 29/2493 Wheel shaped probes
• CPC Class Codes: Y10T 83/155 Optimizing product from unique workpiece
• CPC Class Codes: Y10T 83/178 Responsive to work

Abstract

Ultrasonic techniques are applied to the measurement of wooden members to detect splitting during sawing operations and thereby allow modification of a sawing technique or change in saw cut placement.

Claims

1. A method of detecting anomalies during the sawing of a wooden member, comprising the steps of:

applying a driving signal to a first ultrasonic transducer to produce an ultrasonic wave of known characteristics;

transmitting said ultrasonic wave through said wooden member; and

receiving said ultrasonic wave with a second ultrasonic transducer after passage through said wooden member, wherein said first and second ultrasonic transducers are positioned so as to detect anomalies as said anomalies are created in said wooden member by said sawing.

2. The method of claim 1, further comprising the step of measuring one or more characteristics of said ultrasonic wave received at said second ultrasonic transducer.

3. The method of claim 2, further comprising the step of identifying said anomalies as a function of said measured characteristics.

4. The method of claim 2, further comprising the step of comparing said measured characteristics to said known characteristics to identify said anomalies.

5. The method of claim 1, further comprising the step of comparing measurements taken at a plurality of different angles with respect to said wooden member so as to detect variations in said measurements indicative of a location of said anomaly in said wooden member.

6. The method of claim 1, further comprising the step of positioning said first and second ultrasonic transducers so as to contact said wooden member at spaced positions around a perimeter of the wooden member in a planar cross-section across a grain of the wooden member.

7. The method of claim 1, further comprising the step of controlling a saw so as to cut around said anomaly.

8. The method of claim 1, wherein said value is selected from a group consisting of:

attenuation of total energy, change in spectral energy distribution, change in phase, time of flight, and spreading of temporal distribution of energy in the ultrasonic wave.

9. The method of claim 1, wherein said value is selected at least two members of a group consisting of:

attenuation of total energy, change in spectral energy distribution, change in phase, time of flight, and spreading of temporal distribution of energy in the ultrasonic wave.

10. The method of claim 1, further comprising the step of positioning said first and second transducers within fifteen inches of an end of said wooden member.

11. A method of detecting splits during the sawing of a wooden member, wherein said splits are created at or near the cut plane of a partially cut wooden member due to the cantilevered weight of an end of said wooden member exerting a force that causes said wooden member to split, comprising the steps of:

transmitting an ultrasonic wave of known characteristics through said wooden member using a first ultrasonic transducer;

receiving said ultrasonic wave after passage through said wooden member using a second ultrasonic transducer, wherein said first and second ultrasonic transducers are positioned so as to detect said splits as said anomalies are created in said wooden member by said sawing;

measuring one or more characteristics of said ultrasonic wave received at said second ultrasonic transducer; and

comparing said measured characteristics to said known characteristics to identify said splits.