COLLAPSIBLE TOLERANCE RINGS WITH WEAK POINTS

In certain embodiments, a method includes positioning a tolerance ring (102) between a bearing assembly (100) and an actuator arm (104). The tolerance ring (102) is compressed so that the tolerance ring buckles at predetermined weak points (106) to position the bearing assembly (100) relative to the actuator arm. In certain embodiments, an assembly includes a tolerance ring (102) buckle-fitted between first (100) and second (104) annular surfaces, the tolerance ring (102) buckled at designated weak points (106) to position the first annular surface (100) to the second annular surface (104).

DETAILED DESCRIPTION

The present disclosure relates to devices, systems, and methods including collapsible tolerance rings. Tolerance rings can be utilized, among other applications, in disc drives to couple actuator arms to actuator pivot bearings/assemblies. Further, tolerance rings can prevent slippage between the arm and bearing assembly during operation of disc drives or during shock events.

Some tolerance ring designs and installation methods include rings with protrusions that frictionally engage with an inner surface of an actuator arm. These rings can be installed by first installing the ring into an actuator arm and then forcibly pressing a bearing assembly into the ring—a press fit where an inner diameter of the ring is smaller than an outer diameter of the bearing assembly. Conversely, rings can first be installed around the bearing and then forcibly pressed into the actuator arm—a press fit where an outer diameter of the ring's protrusions is larger than an inner diameter of the actuator arm. Either way, the act of forcibly pressing a component into another component creates particles as surfaces scratch against each other, particularly when a metal surface is involved.

Certain embodiments of the present disclosure are accordingly directed to systems, devices, and methods for reducing particle generation by utilizing collapsible tolerance rings.

FIG. 1provides an exploded view of a bearing assembly100, tolerance ring102, and actuator arm104.FIG. 2provides a closer view of the tolerance ring102including weak points106. The tolerance ring102is a strip formed into a cylindrical or annular shape and is shown as having a gap108between ends of the strip. The weak points106are arranged around the tolerance ring102in two rows—an upper row110and a lower row112. The weak points106can be uniformly or non-uniformly spaced. As shown inFIG. 2, the weak points106can be formed by including slots114with triangular ends116, where a weak point a remaining portion material between and around the slots114. When formed by slots114with triangular ends116, the weak points106take on an hourglass-like shape. However, the weak points106can be formed from shapes other than slots and triangles. For example, the weak points106can be diamond-shaped, circular, square, among other shapes. The slots114can have rounded or square ends, among other shapes. Further, in certain embodiments, slots could be replaced with grooves or other indents on the outer surface of the tolerance ring102that do not go completely through a thickness of the tolerance ring102.

The weak points106are designed to buckle or collapse upon an axial load or force being applied to the tolerance ring102. The weak points106can buckle inwards or outwards, depending on the configuration of the tolerance ring102and weak points106. The upper row110of weak points106can be configured to collapse after the lower row112of weak points106. For example, the lower row112can be designed to be weaker than the upper row110. Doing so allows, during assembly, for a force that is exerted on a top of the tolerance ring102to be translated through the upper row110of weak points106to the lower row112to collapse and expand to position the tolerance ring102against a bottom portion of a bearing assembly and actuator arm. The upper row110of weak points106can be collapsed next using a second force to position an upper portion of the bearing assembly and actuator arm. In certain embodiments, the upper and low rows of weak points can have a converse strength relationship or an equal relationship, depending on the desired order of assembly. The tolerance ring102can be made from a variety of materials, for example, metals like steel or aluminum, among others.

FIG. 3Aprovides a perspective view of a tolerance ring300. The tolerance ring300has an inner surface302and an outer surface304. The tolerance ring300includes weak points306, shown as a portion of the tolerance ring300between slots308. As shown inFIG. 3B, an indent310is formed at the inner surface302along the weak points306so that a thickness of the tolerance ring300is smaller at the weak points306. The indent310, in addition to the weak points306, further reduces the tolerance ring's ability to withstand buckling or collapse under pressure. Indents can be positioned at or around a single row of weak points, or any combination of rows of weak points.

FIG. 4is a side view of a bearing assembly400, tolerance ring402, and a portion of an actuator arm404. The tolerance ring402includes weak points406and is buckled-fitted between the bearing assembly400and actuator arm404. The weak points406can be arranged around the tolerance ring at multiple rows and can be uniformly spaced. As shown inFIG. 4, the tolerance ring402is buckled-out at the weak points406such that the tolerance ring's diameter expands to position the bearing assembly400relative to the actuator arm404. For example, the tolerance ring402couples the bearing assembly400to the actuator arm404. As shown by arrows pointed toward the top of the tolerance ring402, an axial force or load is applied to the top of the tolerance ring402to cause the tolerance ring402to buckle at the weak points406. The buckling and actual fit of the tolerance ring402shown inFIG. 4is exaggerated so that features and the relationship between the features are clearly shown.

FIG. 5is a side view of a bearing assembly500, tolerance ring502, and a portion of an actuator arm504. The tolerance ring502includes weak points506and is buckled-fitted between the bearing assembly500and actuator arm504. The weak points506can be arranged around the tolerance ring at multiple rows and can be uniformly spaced. As shown inFIG. 5, the tolerance ring502is buckled inwards at the weak points506. This configuration is reversed from the configuration ofFIG. 4. As shown by arrows pointed toward the top of the tolerance ring502, an axial force or load is applied to the top of the tolerance ring502to cause the tolerance ring502to buckle inward at the weak points506. The buckling and actual fit of the tolerance ring502shown inFIG. 5is exaggerated so that features and the relationship between the features are clearly shown.

FIG. 6is a perspective view of a collapsed tolerance ring600. As shown in a close-up view, when collapsed, the tolerance ring600deforms and expands outward. The tolerance ring600buckles outward at predetermined or designated weak points602. The weak points602are surrounded by punched-out portions604of the tolerance ring600, thereby reducing the strength of the tolerance ring600at and around the weak points602.

FIG. 7provides a routine illustrative of steps carried out in accordance with certain embodiments. Step700includes positioning a tolerance ring between a bearing assembly and an actuator arm. Step702includes compressing the tolerance ring so that the tolerance ring buckles outward at predetermined weak points to position the bearing assembly relative to the actuator arm. An axial load can be used to compress the tolerance ring, resulting in a shortened height of the tolerance ring. The compressing step couples the bearing assembly to the actuator arm. As described above, the tolerance ring can be designed so that a lower row of weak points buckle before an upper row of weak points, or vice versa, depending on an order of assembly.