To realize the stable inspection of a failure due to the poor bonding between a bottom paper and a cone paper by a method wherein the leakage of a paper cup is judged on the basis of the change of the air pressure within the paper cup with time by controlling the deformation of the paper cup and the supply of a compressed air.
By adhering a lid member 2 with the feed port of a compressed air to the flange of a paper cup 1, the opening part of the paper cup 1 is clogged. After the compressed air is supplied through the feed port within the paper cup 1, the supplying side of the compressed air is closed. The pressure of the compressed air within the paper cup is detected with a pressure detector 3. Even in a case that the paper cup 1 is a defective product having only a poor bonded portion between a bottom paper and a cone paper, by producing a gap in the poor bonded portion between the bottom paper and the cone paper of the paper cup 1, the leakage of the compressed air with time becomes larger. Accordingly, a non-defective paper cup 1 is distinguished from defective one.
SAKATA HIDETO
TAKAGI ZENEI
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