Design and application of a device for measuring the water absorption thickness expansion rate of artificial boards

The thickness expansion rate of wood-based panels after water absorption is an important indicator of their water resistance and dimensional stability. It is the ratio of the increase in thickness after water absorption to the thickness before water absorption. Currently, most methods for measuring the thickness expansion rate of wood-based panels, such as particleboard, fiberboard, and oriented strand board, are based on the requirements of Section 4.4 of GB/T 17657-2013, "Test Methods for Physical and Chemical Properties of Wood-Based Panels and Faced Wood-Based Panels."

According to this regulation, the test specimen surface must be perpendicular to the water surface, with a minimum distance of 15 mm between specimens and between them and the bottom and walls of the water tank. The top of the specimen must be (25±5) mm below the water surface. However, due to the physical properties of the wood-based panel material, the buoyancy in water is greater than its weight, causing the specimen to float. The measurement standard does not provide a device or method to address this issue.

The author's unit has researched and designed a device for measuring water absorption thickness expansion rate and has applied for and obtained a national utility model patent. This article focuses on the structure and design principle of the device for reference by colleagues in the industry.

1 Design model of water absorption thickness expansion rate measuring device

2. Design principle of the device for measuring water absorption thickness expansion rate

2.1 Device size design principle description

2.2 Device Material Description

The material of the water absorption thickness expansion rate measuring device is preferably made of round steel, the gravity of which is much greater than the sum of the buoyancy of the device and the test piece in water, which can ensure that the test device is stably sunk to the bottom and does not tilt during the test.

3 Application of water absorption thickness expansion rate measuring device

4 Conclusions and Recommendations

The design principle of this device is scientific and reasonable, meeting standard requirements. In actual water absorption thickness expansion rate measurement applications, operation is simple and convenient, the specimen remains stable in water and does not tilt, and it meets the requirements for specimen position when immersed in water as specified in Section 4.4 of GB/T 17657-2013.

Each testing and inspection organization can refer to the design principles of this device and design a test device suitable for their organization without compromising the requirements of GB/T 17657-2013 for the determination of water absorption thickness expansion rate. For example, based on this device, the inner width of the fixed small unit can be designed to be adjustable, so that a single device can be used to determine the water absorption thickness expansion rate of wood-based panels of various thicknesses. Furthermore, it is recommended that when revising GB/T 17657-2013, consideration be given to providing corresponding devices or methods to facilitate implementation of the standard by various organizations.