Base plate and disk drive device
A base plate includes a support part, a bottom plate part, and a wall part. The wall part includes a first wall part and a second wall part above the first wall part. The first wall part includes a first wall surface and a support surface spreading from an upper end of the first wall surface to a radially outer side. The second wall part includes a second wall surface and a recess recessed to the radially outer side from the second wall surface. The recess is defined by a space enclosed by a recess wall surface located on the radially outer side of the second wall surface and extending upward from the support surface, a recess top surface connecting from an upper end of the recess wall surface to the second wall surface, and a recess support surface facing the recess top surface in an axial direction.
1. A base plate which defines a part of a housing of a disk drive device, the base plate comprising:
a support part that supports a motor causing a disk to rotate around a central axis extending in an up-down direction;
a bottom plate part that spreads from the support part to a radially outer side; and
a wall part that stands up from an outer peripheral part of the bottom plate part, wherein
the wall part comprises:
a first wall part; and
a second wall part located above the first wall part,
the first wall part comprises:
a first wall surface that encloses the disk from the radially outer side; and
a support surface that spreads from an upper end of the first wall surface to the radially outer side,
the second wall part comprises:
a second wall surface located on the radially outer side of the first wall surface; and
a recess that is recessed to the radially outer side from the second wall surface, and
the recess is defined by a space enclosed by:
a recess wall surface that is located on the radially outer side of the second wall surface and extends upward from the support surface;
a recess top surface that connects from an upper end of the recess wall surface to a lower end of the second wall surface; and
a recess support surface which is a portion of the support surface that faces the recess top surface in an axial direction.
2. The base plate according to claim 1 , wherein
a width in a radial direction from the second wall surface to the recess wall surface is 25% or less of a width of the second wall part in the radial direction.
3. The base plate according to claim 1 , wherein
a width in a radial direction from the second wall surface to the recess wall surface is 30 μm or more.
4. The base plate according to claim 1 , wherein
at least one of a first corner between the recess support surface and the recess wall surface and a second corner between the recess top surface and the recess wall surface is inclined with respect to a radial direction and the axial direction.
5. The base plate according to claim 1 , wherein
the lower end of the second wall surface is located higher than the upper end of the recess wall surface, and
at least a part of the recess top surface has an inclined surface that is inclined upward and connects to the lower end of the second wall surface.
6. The base plate according to claim 1 , wherein
a width in the axial direction between the recess support surface and the recess top surface is larger than a width in a radial direction between the second wall surface and the recess wall surface.
7. The base plate according to claim 1 , wherein
the support surface has a surface roughness smaller than at least a part of an outer wall surface of the wall part facing the radially outer side.
8. The base plate according to claim 1 , wherein
the support surface including the recess support surface, the recess wall surface, and the recess top surface are covered with an electrodeposition coating film.
9. The base plate according to claim 1 , wherein
at least a part of the wall part is a surface covered with an electrodeposition coating film, and
at least the support surface is exposed from the electrodeposition coating film.
10. A disk drive device comprising:
the base plate according to claim 1 ;
a first cover part arranged at an upper part of the base plate; and
a seal member, wherein
the seal member is arranged on the support surface including the recess support surface, and
a radially outer end of the first cover part is connected to the support surface via the seal member.
11. The disk drive device according to claim 10 , further comprising:
a second cover part arranged above the first cover part, wherein
a radially outer end of the second cover part is connected to an upper end surface of the wall part.