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This is a record of a document published elsewhere, first published by the United States Patent and Trademark Office, as US-5097881-A, on 24 March 1992. OpenTechnical did not first disclose it. The identifier, hashes and timestamps below record what this library served and when, not when the material became public. View the original.

OT-2026-000003401

Ultrasonic log grading

Published
Permanent URL
Classification
Material Handling › Sorting
Assignee
BLOUNT INC
Original source
US-5097881-A, the United States Patent and Trademark Office, 24 March 1992
Document SHA-256
57ef6a02ac8dabe355ea6f6b4df274c9d25559934784aa4ab31821914def943e

A log harvesting system is disclosed in which the log is graded automatically in the field by ultrasonic testing of the log. Pulses of utlrasonic waves are transmitted into the log to detect internal defects within the log by measuring changes in the transient time of the ultrasonic wave pulses through at least a portion of the log. A computer is used to determine the grade of the log and produce a grade output signal from transient time data and signals related to the length and diameter of the log. The log is marked with a different colored paint to indicate its grade by an automatic marking device in response to the receipt of the grade output signal. Ultrasonic testing apparatus may be added to a tree harvesting head with a saw for felling the tree and cutting the log to the proper length and delimber knives for removing limbs, in order to test the log for defects as the log is conveyed through such head. In one embodiment, a pair of ultrasonic transducer wheels are mounted on opposite sides of the log and pairs of transmitting and receiving transducers are selectively coupled to the log through liquid coupling chambers provided on the outer surface of such wheels as the wheels rotate along the length of the log.

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Abstract

A log harvesting system is disclosed in which the log is graded automatically in the field by ultrasonic testing of the log. Pulses of utlrasonic waves are transmitted into the log to detect internal defects within the log by measuring changes in the transient time of the ultrasonic wave pulses through at least a portion of the log. A computer is used to determine the grade of the log and produce a grade output signal from transient time data and signals related to the length and diameter of the log. The log is marked with a different colored paint to indicate its grade by an automatic marking device in response to the receipt of the grade output signal. Ultrasonic testing apparatus may be added to a tree harvesting head with a saw for felling the tree and cutting the log to the proper length and delimber knives for removing limbs, in order to test the log for defects as the log is conveyed through such head. In one embodiment, a pair of ultrasonic transducer wheels are mounted on opposite sides of the log and pairs of transmitting and receiving transducers are selectively coupled to the log through liquid coupling chambers provided on the outer surface of such wheels as the wheels rotate along the length of the log.

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Publication information

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Citation

OpenTechnical Publication OT-2026-000003401, “Ultrasonic log grading,” published September 15, 2026 at 20:22:27 UTC, https://opentechnical.org/p/OT-2026-000003401.

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