Static bending apparatus for grading wood panels

US4589288A · kind A · utility

Assignee

• Her Majesty the Queen in right of the Province of Alberta, as represented by the Minister of Energy and Natural Resources · CA

Inventors

• Andrew W. Porter · Richmond, CA
• Lars Bach · Ullersdorf, DE

Key dates

• Filing date: Feb 8, 1985
• Grant date: May 20, 1986
• Expiry date: Feb 8, 2005

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N33/46
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A non-destructive method and apparatus is provided for testing a wood panel, such as a sheet of plywood, to establish values which may be used in calculating a measure of the modulus of elasticity (MOE) for the panel. The invention involves supporting the bottom surface of the panel horizontally with two spaced parallel rollers and contacting the top surface of the panel with a pivotally mounted loading bar which is adapted to apply linear loading to the panel substantially uniformly across its width, even though the panel may be warped or bent. The loading bar is biased by a double-acting cylinder so as to apply a first load and then, in quick succession, a second incremental load. The two loads are selected so as to fall on the substantially linear portion of the load deflection curve for the panel. The magnitudes of the two loads are measured with suitable means, such as a load cell. The extension or distance moved by the cylinder in applying the incremental load is known or measured. With the two loadings and the incremental deflection established, one can calculate, using standard formulae, a value which is found to closely approximate the MOE.