Damped disc drive assembly, and method for damping disc drive assembly
View Patent ↗A disc drive assembly is provided including a head disc assembly, a housing having a base and a cover cooperating with one another to form a chamber in which the head disc assembly is housed, and a damper structure in operative association with the housing for dampening noise and/or vibration emanated from the head disc assembly. The damper structure includes a viscoelastic damper layer and a continuous, polymeric constraining layer intimately contacting and encasing the viscoelastic damper layer. The constraining layer has a greater stiffness and higher modulus of dynamic shearing elasticity than the viscoelastic damper layer, and is molded from a high density filler and a moldable compound that is immiscible with the viscoelastic damper layer to provide a discrete interface between the constraining layer and the viscoelastic damper layer.
1. A method for damping a disc drive assembly, comprising:
providing a disc drive assembly comprising a head disc assembly and a housing, the head disc assembly comprising a disc having a surface and a track for storage of information, a head for writing and reading information to and from the disc, and an actuator arm for moving the head relative to the surface of the disc, the housing comprising a base and a cover cooperating with one another to form a chamber there between in which at least a portion of the head disc assembly is housed;
heat molding a curable compound in a mold cavity of a mold in the presence of a viscoelastic damper layer that is substantially immiscible with the curable compound, and curing the curable compound into a continuous, polymeric constraining layer of a damper structure, the damper structure comprising the constraining layer in intimate contact with and encasing the viscoelastic damper layer, the constraining layer having a greater stiffness and higher modulus of dynamic shearing elasticity than the viscoelastic damper layer; and
positioning the damper structure in operative association with the housing to dampen noise and/or vibration resonating from the disc drive assembly.
2. A method according to claim 1 , wherein the viscoelastic damper layer comprises a polymeric reaction product of a composition comprising a member selected from the group consisting of (meth)acrylic acid and (meth)acrylate.
3. A method according to claim 1 , wherein the viscoelastic damper layer comprises a polyacrylate.
4. A method according to claim 1 , wherein the viscoelastic damper layer comprises a member selected from the group consisting of nitrile rubbers and fluoroelastomers.
5. A method according to claim 1 , wherein the viscoelastic damper layer is free of fillers.
6. A method according to claim 1 , wherein the viscoelastic damper layer comprises a plurality of fragments that are noncontinuous with each other to provide interstices between the noncontinuous fragments.
7. A method according to claim 1 , wherein the constraining layer further comprises high density filler comprising a member selected from the group consisting of glass, carbon, aramids, metal, plastics, alumina, silica, silicon, ceramic, and graphite.
8. A method according to claim 1 , wherein the constraining layer further comprises chopped fiberglass.
9. A method according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least two orders of magnitude greater than that of the viscoelastic damper layer.
10. A method according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least three orders of magnitude greater than that of the viscoelastic damper layer.
11. A method according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least about 500,000 psi.
12. A method according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least about 1,000,000 psi.
13. A method according to claim 1 , wherein the constraining layer comprises a member selected from the group consisting of epoxy, polyurethane, polyester, acetal, polystyrene, acrylonitrile-butadiene-styrene, and polyvinylchloride.
14. A method according to claim 1 , wherein the constraining layer comprises a polyester.
15. A method according to claim 1 , wherein said positioning comprises placing the damper structure in intimate contact with an outer surface of the housing.
16. A method according to claim 1 , wherein said positioning comprises placing the damper structure in intimate contact with an inner surface of the housing.
17. A method for damping a disc drive assembly, comprising;
providing a disc drive assembly comprising a head disc assembly and a housing, the head disc assembly comprising a disc having a surface and a track for storage of information, a head for writing and reading information to and from the disc, and an actuator arm for moving the head relative to the surface of the disc, the housing comprising a base and a cover cooperating with one another to form a chamber there between in which at least a portion of the head disc assembly is housed;
heat molding a curable compound in a mold cavity of a mold and curing the curable compound into a continuous, polymeric constraining layer;
forming a damper structure comprising the continuous, polymeric constraining layer in intimate contact with a viscoelastic damper layer that is substantially immiscible with the curable compound, the constraining layer having a greater stiffness than the viscoelastic damper layer, a modulus of dynamic shearing elasticity of at least 500,000 psi and higher than the viscoelastic damper layer, and a density of at least 3.0 grams per cubic centimeter; and
positioning the damper structure in operative association with the housing to dampen noise and/or vibration resonating from the disc drive assembly.
18. A method according to claim 17 , wherein the viscoelastic damper layer comprises a polymeric reaction product of a composition comprising a member selected from the group consisting of (meth)acrylic acid and (meth)acrylate.
19. A method according to claim 17 , wherein the viscoelastic damper layer comprises a polyacrylate.
20. A method according to claim 17 , wherein the viscoelastic damper comprises a member selected from the group consisting of nitrile rubbers and fluoroelastomers.
21. A method according to claim 17 , wherein the viscoelastic damper layer is free of fillers.
22. A method according to claim 17 , wherein the viscoelastic damper layer comprises a plurality of fragments that are noncontinuous with each other to provide interstices between the noncontinuous fragments.
23. A method according to claim 17 , wherein the constraining layer further comprises high density filler comprising a member selected from the group consisting of glass, carbon, aramids, metal, plastics, alumina, silica, silicon, ceramic, and graphite.
24. A method according to claim 17 , wherein the constraining layer further comprises chopped fiberglass.
25. A method according to claim 17 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least two orders of magnitude greater than that of the viscoelastic damper layer.
26. A method according to claim 17 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least three orders of magnitude greater than that of the viscoelastic damper layer.
27. A method according to claim 17 , wherein the constraining layer comprises a member selected from the group consisting of epoxy, polyurethane, polyester, acetal, polystyrene, acrylonitrile-butadiene-styrene, and polyvinylchloride.
28. A method according to claim 17 , wherein the constraining layer comprises a polyester.
29. A method according to claim 17 , wherein the density of the constraining layer is at least 5.0 grams per cubic centimeter.
30. A method according to claim 17 , wherein said positioning comprises placing the damper structure in intimate contact with an outer surface of the housing.
31. A method according to claim 17 , wherein said positioning comprises placing the damper structure is in intimate contact with an inner surface of the housing.