Detection of plywood bonding strength and boiling test
Detection of plywood bonding strength and boiling test

Detection of plywood bonding strength and boiling test

Detection of plywood bonding strength and boiling test

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Main contents and scope of application This standard specifies the measurement method of bonding strength of ordinary plywood defined by GB9846.2.

2. Referring to the standard GB9846.2 plywood terminology and defining the extraction method for measuring bonding strength of GB9846.8 plywood. Measurement of dimensions of sawn GB9846.10 plywood specimens of GB9846.9 plywood specimens

3 Gauges and Instruments

_3.1 vernier caliper, the reading accuracy of indexing is 0.01g. 3.2 Constant temperature water bath pot, 30-100 C.

3.3 tension testing machine, load reading accuracy is 5N.

3.4 air convection drying chamber, the temperature of each point in the chamber can be maintained at 63 + 3 C.

4 Samples and specimens

4.1 Samples were taken according to GB9846.8. 4.2 Saw specimens according to GB9846.9.

4.3 Specimens should not contain material defects and processing defects that affect bonding strength in the shear section.

5 Procedures

5.1 Measure the size of the specimen according to GB9846.10.

5.2 specimens were treated under the following conditions according to their plywood types:

A.Class I plywood: boil the sample in boiling water for 4 hours, then dry it in air convection drying box at 63 (+3 C) for 20 hours, then boil it in boiling water for 4 hours, then cool it at room temperature for 10 minutes. When boiling the specimens, all the specimens should be immersed in boiling water and covered with boiling water. Note: Rapid inspection method of 3H boiling is allowed in factory production. The measured result multiplied by coefficient 0.9 is used as the bonding strength value of product inspection. However, when there is disputed demand between supply and demand sides, the method of 28h boiling-drying cycle is still used as the cutting promotion method. B.II plywood: The specimen was immersed in 63 3 C hot water for 3 hours, and then cooled for 10 MIM at room temperature. When impregnating the specimens, all the specimens should be immersed in hot water and covered.

Note: Rapid inspection method of 63 3 C and impregnation for 1 hour is allowed in factory production. The measured results multiply by coefficient 0.82 as the bonding strength value of product inspection. However, in case of disputes between suppliers and demanders, the method of 3 h hot water impregnation is still used as the arbitration method.

C.III plywood: The specimens were immersed in water at 63 3 for 2 hours, then dried in air convection drying box at 63 3 C. III for 1 hour separately. After removal, the specimens were placed at room temperature for 10 minutes.

_d.IV plywood: Dry test was carried out on specimens with water content meeting the requirements. Note: The water content of the specimen should be controlled in 8%-12%5.3. The two ends of the specimen should be clamped in a pair of movable fixtures of the testing machine to make it in a straight line. The center of the specimen should pass through the axis of the movable fixture of the testing machine. The distance between the clamping position and the notch of the specimen should be within 5 mm.

5.4 loads the specimens at the same speed until they are destroyed. The loading speed is 10 MPa/min. The maximum damage load reading should be accurate to 5N.

6. Calculation and representation of test results

6.1 According to the damage situation of rubber layer in shear section, the wood damage rate of the specimen is estimated by visual measurement, expressed by percentage, and the estimation accuracy is 10%. Refer to Appendix B (Reference Part). If the specimen is damaged abnormally, the failure characteristics (groove breakage, surface plate splitting, core plate cutting, or surface plate peeling) are recorded. Refer to Appendix C (References). Note: When the peeling area of the surface plate exceeds half of the shear area, the damage rate of the wood can be estimated accurately to 10%.

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