PURPOSE: To increase strength such as tightening force and improve sealing performance by forming a lock sleeve over a joint where a pipe is inserted into another pipe with the lock sleeve being formed in layers with the outer layer made of a soft and resilient material and the inner layer made of a hard and rigid material.
CONSTITUTION: A pipe 1 is inserted into a pipe 2. A forming mold is placed over the pipes for the over injection of a lock sleeve 3 over the circumference of the joint. A plastic material 7 is injected into the mold for forming an outer layer of the lock sleeve 3. The plastic material 7 for forming an inner layer is injected while the plastic material for forming the outer layer is pushed outward. The mold is then removed. The lock sleeve 3 is formed in layers following the rugged shape formed on the outer circumference of the pipes 1 and 2. As a result, sealing is maintained with the resilient contact with the outer circumferential surface of the pipe of the soft outer resilient layer and the strength such as the tightening force is effected with the inner hard rigid layer.
HOSHIJIMA HIROYUKI
HAYASHIBARA TAKASHI
OGAWA TAIDO
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