Browse Prior Art Database

Light, Reliable, Contamination-free Tie Rod

IP.com Disclosure Number: IPCOM000120000D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Watrous, R: AUTHOR

Abstract

This article describes a method for securely fastening a stack of ceramic arms and spacer blocks to a storage file actuator. The scheme relies on the cooling contraction of heated bolts. As shown in the figure, the stack of arms and spacers accepts two through bolts each having a head on one end and a separate collar on the other. The bolts, but not the stack of ceramic parts, are heated and then the collars are laser welded to the bolts. As the bolts cool and shrink a purely compressive clamping force, of predictable value, is applied to the stack. Conventional nuts and bolts generate both clamping forces and twisting torques, the values of which vary considerably depending on thread friction as well as the friction between the nut and the clamped surface.

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Light, Reliable, Contamination-free Tie Rod

      This article describes a method for securely fastening a
stack of ceramic arms and spacer blocks to a storage file actuator.
The scheme relies on the cooling contraction of heated bolts.  As
shown in the figure, the stack of arms and spacers accepts two
through bolts each having a head on one end and a separate collar on
the other.  The bolts, but not the stack of ceramic parts, are heated
and then the collars are laser welded to the bolts.  As the bolts
cool and shrink a purely compressive clamping force, of predictable
value, is applied to the stack.  Conventional nuts and bolts generate
both clamping forces and twisting torques, the values of which vary
considerably depending on thread friction as well as the friction
between the nut and the clamped surface.  Heavier, oversize bolts are
typically used to mask these variations and to accommodate the
twisting stresses.  In addition debris, which is very detrimental in
a storage file, is generated when nuts are tightened.  And, finally,
epoxy, or other means, must be used to prevent nuts from vibrating
loose.

      There are two proposed methods for heating the bolts. The
first, resistive heating, is accomplished by passing an electrical
current through the bolts (the non-conductive ceramic parts do not
provide a short circuit path).  Heating the bolts causes them to
expand in both length and diameter; however, the length-to-diameter
ratio is large so the di...