Press die of disk with shaft shaped portion

1. A press die for press molding of a glass substrate of a disk member with a shaft shaped portion at a center thereof, comprising:

an upper die forming an upper surface of said disk member;

an intermediate die having a shaft forming hole portion for forming a shaft shaped portion projecting from a disk portion of said disk member, and forming at least a lower surface of said disk portion;

a lower die for forming a lower surface of said shaft shaped portion;

wherein said lower die being separate from said intermediate die, and contact surfaces between said intermediate die and said lower die having a surface roughness that permits discharge of gas enclosed in said intermediate die and said lower die.

2. A press die according to claim 1 , further comprising a guide member for guiding said upper die, said intermediate die and said lower die.

3. A press die according to claim 2 , wherein said guide member defines depression amount of a press by said upper die upon press molding.

4. A press die according to claim 1 wherein said intermediate die further has a circular recess for forming at least a lower surface of said disk portion.

5. A press die according to claim 4 , wherein a depth of said circular recess of said intermediate die is greater than or equal to a half of a height of said disk portion.

6. A press die according to claim 4 , wherein a depth of said circular recess of said intermediate die is equal to a height of said disk and an upper surface of said intermediate die defines depression amount of a press by said upper die during press molding operation.

7. A press die according to claim 4 , wherein said intermediate die is formed with an outer frame and a bottom frame, said circular recess is defined by said outer frame and said bottom frame, and said outer frame defines depression amount of a press by said upper die during press molding operation.

8. A press die for press molding glass substrates of disk members each having a shaft shaped portion at a center, comprising:

an upper die for performing press molding from an upper surface;

an intermediate die having a plurality of shaft forming hole portions for forming shaft shaped portions, said shaft forming hole portions being arranged in a manner not interfering with each other;

a lower die for forming a lower surface of said shaft shaped portions, said lower die being separate from said intermediate die, contact surfaces between said intermediate die and said lower die having a surface roughness that permits discharge of enclosed in said shaft forming portions through a gap between said intermediate die and said lower die; and

a height restricting member for determining depression amount of a press.

9. A press die for press molding a glass substrates of disk members each having a shaft shaped portion at a center, comprising:

an upper die for performing press molding from an upper surface;

a plurality of intermediate dies, each having a shaft forming hole portion for forming the shaft shaped portion; and

a lower die for forming a lower surface of each said shaft shaped portion;

wherein said lower die being separate from said intermediate dies, and contact surfaces between each said plurality of intermediate dies and said lower die having a surface roughness that permits discharge of gas enclosed in each said shaft forming hole portion through a gap between the plurality of intermediate dies and the lower die; and

a height restricting member for determining depression amount of a press.