| abstract |
A tube blank 2' whose inside is divided into an air chamber 3 and a sealant chamber 7 by a partition wall 5 has an air relief port 4 1 provided in a sealant chamber peripheral wall 4o and communicating a sealant chamber 7. At a vulcanizing step, the tube blank 2' is placed into a heating die 18, and a gas of a high temperature and a high pressure is supplied into an air chamber 3. This causes air remaining in the sealant chamber 7 to be discharged through the air relief port 4 1 , while bringing the partition wall 5 into close contact with the sealant chamber peripheral wall 4o, thereby performing a reliable vulcanization. When the tube blank 2' is removed from the heating die 18, the sealant chamber 7 is not expanded because of the existing of the air relief port 4 1 and therefore, the partition wall 5 cannot be provided with an expanding tendency that forces the wall 5 to be stretched toward the air chamber peripheral wall 4i. |