板紙の圧縮強さ試験における機差の検討について

抄録

The compressive strength (ring crush) of paperboard is an important property to estimate the compressibility of box and therefore the ring crush in cross direction has been specified in the Japanese Industrial Standard of linerboard and corrugating medium. At present, compression testing apparatus by beam type are generally used to measure ring crush strength, however, this method has been a subject of discussion for a long time because of their instrumental errors of more than 10 percent.
Under the circumstances, the Linerboard Technical Committee of Japan Paper Association studied the factors of these errors, making comparison of the data obtained with the use of the beam type and strain gauge type of apparatus The result was that among many factors the level of parallelling of the upper and lower compression platens with each other had a most significant effect on the errors. As for the strain gruge type of apparatus we used, they turned out to be poorer in preciseness than well-cared beam type ones. The reason seems to be that we used the type mainly designed for measuring tensile strength. However, it is considered that a strain gauge type is essentially superior to a beam type in terms of instrumental precision. We expect that a special type of strain gauge testing apparatus will be developed to measure the ring crush.