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 disc drive assembly comprising:
a 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;
a housing comprising a base and a cover cooperating with one another to form a chamber therebetween in which at least a portion of the head disc assembly is housed; and
a damper structure operatively associated with the housing for dampening noise and/or vibration emanated from the head disc assembly, the damper structure comprising
a viscoelastic damper layer; and
a continuous, polymeric constraining layer intimately contacting 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, the constraining layer being 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.
2. A disc drive assembly 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 disc drive assembly according to claim 1 , wherein the viscoelastic damper layer comprises a polyacrylate.
4. A disc drive assembly according to claim 1 , wherein the viscoelastic damper layer comprises a member selected from the group consisting of nitrile rubbers and fluoroelastomers.
5. A disc drive assembly according to claim 1 , wherein the viscoelastic damper layer is free of fillers.
6. A disc drive assembly 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 disc drive assembly according to claim 1 , wherein the viscoelastic damper layer is continuous and non-fragmented.
8. A disc drive assembly according to claim 1 , wherein the continuous 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.
9. A disc drive assembly according to claim 1 , wherein the constraining layer further comprises chopped fiberglass.
10. A disc drive assembly 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.
11. A disc drive assembly 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.
12. A disc drive assembly according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least about 500,000 psi.
13. A disc drive assembly according to claim 1 , wherein the modulus of dynamic shearing elasticity of the constraining layer is at least about 1,000,000 psi.
14. A disc drive assembly 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.
15. A disc drive assembly according to claim 1 , wherein the constraining layer comprises a polyester.
16. A disc drive assembly according to claim 1 , wherein the damper structure is in intimate contact with an outer surface of the housing.
17. A disc drive assembly according to claim 1 , wherein the damper structure is in intimate contact with an inner surface of the housing.
18. A disc drive assembly comprising:
a 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;
a housing comprising a base and a cover cooperating with one another to form a chamber therebetween in which at least a portion of the head disc assembly is housed; and
a damper structure operatively associated with the housing for dampening noise and/or vibration emanated from the head disc assembly, the damper structure comprising
a viscoelastic damper layer; and
a continuous, polymeric constraining layer intimately contacting the viscoelastic damper layer and molded from a high density filler and a melt-flowable polymer matrix that is immiscible with the viscoelastic damper layer to provide a discrete interface between the constraining layer and the viscoelastic damper layer, 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.
19. A disc drive assembly according to claim 18 , 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.
20. A disc drive assembly according to claim 18 , wherein the viscoelastic damper layer comprises a polyacrylate.
21. A disc drive assembly according to claim 18 , wherein the viscoelastic damper layer comprises a member selected from the group consisting of nitrile rubbers and fluoroelastomers.
22. A disc drive assembly according to claim 18 , wherein the viscoelastic damper layer is free of fillers.
23. A disc drive assembly according to claim 18 , wherein the viscoelastic damper layer comprises a plurality of fragments that are noncontinuous with each other to provide interstices between the noncontinuous fragments.
24. A disc drive assembly according to claim 18 , 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.
25. A disc drive assembly according to claim 18 , wherein the constraining layer further comprises chopped fiberglass.
26. A disc drive assembly according to claim 18 , 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.
27. A disc drive assembly according to claim 18 , 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.
28. A disc drive assembly according to claim 18 , wherein the constraining layer comprises a member selected from the group consisting of epoxy, polyurethane, polyester, acetal, polystyrene, acrylonitrile-butadiene-styrene, and polyvinylchloride.
29. A disc drive assembly according to claim 18 , wherein the constraining layer comprises a polyester.
30. A disc drive assembly according to claim 18 , wherein the density of the constraining layer is at least 5.0 grams per cubic centimeter.
31. A disc drive assembly according to claim 18 , wherein the damper structure is in intimate contact with an outer surface of the housing.
32. A disc drive assembly according to claim 18 , wherein the damper structure is in intimate contact with an inner surface of the housing.