Disk drive suspension having a coined baseplate

A baseplate that is configured to be included in a hard disk drive suspension assembly, and a related method for manufacturing the baseplate. The baseplate having a surface that has been coined to reduce any roughness that might have existed in a portion of the surface before the surface was coined.

BACKGROUND

1. Field of the Invention

The present invention relates generally to suspension systems, also referred to as suspension assemblies, for hard disk drive systems. More specifically, the present invention relates to providing tooling features integral to the suspension system to aid in forming suspension system components, and to coining one or more surfaces of a component that is used as part of the suspension system to remove roughness.

2. Related Art

Suspension systems for suspending read/write heads in hard disk drives are well known in the art. In a typical hard disk drive suspension system, the read/write head is mounted on a slider having an aerodynamic design, such that airflow between the slider and a spinning disk generates lift that allows the head to fly above the disk surface an optimal distance for reading data from the surface or writing data to the surface. The slider is typically bonded to a flexure (or gimbal), which permits the slider to pitch and roll as it tracks fluctuations in the disk surface. The flexure is coupled to a load beam, which is formed from a metal such as stainless steel and configured with a spring portion that applies a loading force, also known as a “pre-load” or “gram force”, to counteract the lift. A rigid end of the load beam is coupled to a baseplate, where an actuator is provided for precisely positioning the read/write head through actuation of the load beam.

The spring portion of the load beam is a linear flex-spring, or planar cantilever-type spring, typically formed from a metal sheet. The desired pre-load force is achieved by forming one or more bends in the linear spring portion of the load beam, taking into account the spring constant of the material, its mass, and the expected load.FIG. 1illustrates a typical suspension assembly100consisting of a baseplate102, springs104, and load beam106. In one commonly practiced technique, during manufacture of the assembly100springs104are preloaded using appropriate forming tools, such as tooling anvil108and roller110. Springs104are bonded to the underside of baseplate102and load beam106to allow for placement of tooling anvil108at an optimal bend location112beneath the springs. So located, a bendable area114of each spring104is bent around a corner140of tooling anvil108under pressure of roller110as it pushes downward and rolls away from baseplate102in the directions shown by dashed lines. The resulting bend angle radius of spring104is therefore influenced by the curvature of corner140. This curvature will change over time after repeated use of tooling anvil108. Eventually, tooling anvil108will need to be replaced to avoid out-of-tolerance formation of bend angle radius in springs104.

The main problem with the foregoing technique is that the accuracy of the bend location depends on placement of tooling anvil108with respect to assembly100. Hard disk drive suspension systems typically demand very strict manufacturing tolerances on the order of 1.0 mil; therefore anvil placement requires high precision tooling, which adds to the manufacturing expense.

Another problem with the conventional anvil-and-roller technique is illustrated inFIG. 2, which shows a side view of a typical suspension assembly200. Assembly200essentially consists of the same components as in assembly100, except that a bridging area214of spring204has a shorter length relative to the diameter of roller210. In suspension assemblies having this dimensional constraint, it may be impossible to impact roller210at the optimal bend location212due to mechanical interference from baseplate202or load beam206. Where springs are bonded to the underside of the assembly, interference occurs as roller210encounters baseplate or load beam steps located above the surface of the spring. The example assembly200illustrates this interference effect: placement of roller210is limited by the step of baseplate202such that impact point216is displaced from optimal bend location212by a horizontal offset Δ. An excessive offset results in formation of the bend in a non-optimal location, or creation of an undesirable secondary bend.

In view of the foregoing, there remains considerable margin for improving pre-loading techniques for disk drive suspension assemblies. Also, surfaces of the baseplate102and202of the suspension assembly100and200, respectively, can have surfaces that are abrasive and can scratch against other components, e.g., the spring104and204and/or the load beam106and206, and/or other parts of a hard disk drive, e.g., load-unload ramps and/or assembly combs, as are known to an individual having ordinary skill in the art, and result in the generation of debris, which can detrimentally affect the operation of the hard drive. These abrasive surfaces, which typically are made from stainless steel, are deburred in a vibratory manner resulting in the generation of additional debris. As magnetic recording technologies advance, they have become increasingly sensitive to smaller size debris. Accordingly, there is a need for suspension assembly baseplates with nonabrasive surfaces. The present invention satisfies these needs.

SUMMARY

The present invention resides in a baseplate having a coined surface that is configured to be included in a hard disk drive suspension assembly, a hard disk drive suspension assembly that includes the baseplate, and a related method for manufacturing the baseplate. An exemplary method according to the invention is a method for manufacturing a baseplate having a surface wherein the baseplate is configured to be included in a hard disk drive suspension assembly. The method includes forming the baseplate in a manner that can create a roughness in a portion of the surface, and coining the surface of the baseplate to reduce the roughness in the portion of the surface.

In other, more detailed features of the invention, the portion of the surface is a die break edge or a die roll edge. Also, the hard disk drive suspension assembly can be configured to be included in a hard disk drive, and the reduction of the roughness in the portion of the surface can result in a reduction in an amount of debris in the hard disk drive. In addition, the hard disk drive suspension assembly can be configured to include a spring, the step of forming the baseplate can include forming an integral anvil in the baseplate, and the integral anvil can be configured to provide an edge for forming a permanent bend in the spring.

In other more detailed features of the invention, the baseplate can have a shape, the baseplate can be made from a sheet of material, e.g., stainless steel, a composite of stainless steel, or a laminate material, and the step of forming the baseplate can include cutting the shape of the baseplate into the sheet of material using a stamp or a die. Also, a station having an insert can be used to coin the surface of the baseplate, and the step of coining the surface of the baseplate can include positioning the surface adjacent to the insert, and using the station to apply a force to the baseplate so the surface contacts and pushes against the insert. In addition, the surface of the baseplate can have a first contour before the surface is coined, the insert can have a second contour, and the force that is applied by the station on the baseplate can cause the first contour of the surface of the baseplate to conform to the second contour of the insert.

An exemplary embodiment of the present invention is a baseplate that is configured to be included in a hard disk drive suspension assembly. The baseplate includes a surface that has been coined to reduce any roughness that might have existed in a portion of the surface before the surface was coined.

In other, more detailed features of the invention, the hard disk drive suspension assembly also is configured to include a spring, and the baseplate includes an integral anvil that is configured to provide an edge for forming a permanent bend in the spring. Also, the edge for forming the permanent bend in the spring can be included in the surface that has been coined.

Another exemplary embodiment of the present invention is a suspension assembly that is configured to be included in a hard disk drive. The suspension assembly includes a baseplate that includes a surface that has been coined. The surface of the baseplate was coined to reduce any roughness that might have existed in a portion of the surface before the surface was coined.

Related systems, methods, features and advantages of the invention or combinations of the foregoing will be or will become apparent to one having ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, advantages and combinations be included within this description, be within the scope of the invention, and be protected by the accompanying claims.

DETAILED DESCRIPTION

In accordance with the foregoing objectives of the invention, preferred embodiments are now described in further detail, which, when read in conjunction with the claims and drawings, give broader meaning and scope to the spirit of the invention.

As utilized herein, terms such as “about” and “substantially” and “approximately” are intended to allow some leeway in mathematical exactness to account for tolerances that are acceptable in the trade, or that would otherwise encompass a functionally equivalent variation. Accordingly, any deviations upward or downward from any value modified by such terms should be considered to be explicitly within the scope of the stated value.

The present invention discloses an improvement in the design of disk drive suspension assemblies. Specifically, the improvement is directed to providing tooling features integral to the suspension system to aid in forming suspension system components. In various embodiments disclosed herein, the tooling feature comprises an anvil integrally formed on a suspension system baseplate. The integral anvil greatly simplifies the process of pre-load forming, or pre-loading, the suspension assembly to counteract the lift force transmitted by the slider. In other embodiments, the improvement is directed to coining surfaces of the formed suspension system components.

FIG. 3shows a top isometric view of one embodiment of a suspension assembly300according to the present invention. The proximal end of the assembly is shown on the left-hand side of the page, and the distal end of the assembly is shown on the right-hand side of the page. Assembly300comprises a baseplate302coupled to a load beam306through a spring (or spring portion)304. In the embodiment shown, spring304is a separate component that is bonded to an upper surface318of baseplate302at a distal end of baseplate302. The opposite end of spring304is bonded to an upper surface320of load beam306at a proximal end of load beam306. In other embodiments, spring304may be formed as an integral part of load beam306. The bonds between spring304and the upper surfaces318and320may be effected by any conventional means; for example, by welding or by use of epoxy glue.

Baseplate302is configured with one or more integral anvils322for pre-load forming of spring304. As shown in the figure, each integral anvil322in this embodiment comprises a tab extending from baseplate302to a position between the distal end of baseplate302and the proximal end of load beam306. Each integral anvil is configured at its distal end with a rounded corner342at the top of a spring-forming edge330. At the spring-forming edge330of each integral anvil322, spring304bends downward about rounded corner342, thereby coupling load beam306at an angle with respect to the upper surface of baseplate302. Baseplate302, spring304, and load beam306are each composed of a metal, typically a stainless steel alloy of substantially uniform thickness. Baseplate302has a thickness several times that of spring304in order to provide effective anchorage during forming or flexing of the spring.

Forming tools are also shown in the figure in their approximate locations when preloading spring304. A tooling anvil308abuts a bottom surface of baseplate302, and a roller tool310is positioned above the assembly approximately directly above an optimal, or desired, bend location on spring304. These tools are not components of assembly300. They are shown to illustrate their cooperation with integral anvils322when forming springs304. Skilled artisans will appreciate that cooperation of assembly300with forming tools308and310requires assembly300to possess certain interfacing features to ensure dimensional compatibility. One example of an interfacing feature is the shape of the bottom surface of baseplate302. In the embodiment shown, the flat configuration of the bottom surface of baseplate302allows baseplate302to firmly abut the top surface of tooling anvil308. This helps to ensure stable positioning of assembly300on tooling anvil308, and also ensures an even distribution of load across the upper surface of tooling anvil308when roller310presses downward to form a permanent bend in spring304. Surface interface configurations other than flat are certainly possible within the scope of the invention. Another example of an interfacing feature comprises placement of the spring-forming edge330of one or more integral anvils322at a location such that the impact point of a roller310may coincide with spring-forming edge330, free of interference from other suspension assembly features or components. Another example of an interfacing feature is a height restriction on limiter326that provides sufficient clearance for the central recessed portion328of roller310to allow unobstructed movement of roller310across the surface of spring304.

FIG. 4shows a side view of an embodiment of the invention during pre-load forming. Note that placement of spring404between roller410and assembly surfaces (in this case, upper surfaces418and420) advantageously eliminates any mechanical interference of those surfaces with roller410. In other words, by locating the baseplate and load beam steps on a surface of spring404opposite roller410, roller410may be freely positioned along a surface of spring404until impact point416substantially coincides with an optimal bend location424. This ability to freely position roller410allows the horizontal offset A to be reduced to approximately zero.

The configuration shown inFIG. 4allows spring404to be bent with minimal error at optimal bend location424as roller410presses downward on spring404forcing it around corner442of integral anvil422, while tooling anvil408abuts baseplate402to provide stability for assembly400during the bending operation. The resulting bend angle radius of spring404is influenced by curvature in corner442, just as it would be influenced by the radius of curvature of corner440using prior art methods. However, it is worth noting that the curvature of corner442and the resulting bend angle radius in spring404are typically unequal. This is due to a springback effect (or resiliency) in spring404, as well as the effect of roller stroke. Although artisans refer to the resulting bend as a “radius”, note that the bend angle in spring404may not always be circular; but may resemble various non-circular forms of curvature such as elliptic, hyperbolic, or parabolic curves. The curvature of corner442may also comprise a circular or non-circular arc. In spring404, the resulting bend angle radius (whether circular or non-circular), its uniformity, and its consistency from spring to spring, contribute significantly to suspension assembly performance. Controlling curvature of bending corner442is therefore an important aspect of quality control.

By controlling parameters such as bending corner curvature, roller force, roller travel, component material compositions and thicknesses, a suspension assembly according to the invention may be pre-loaded to a desired value by creating a permanent bend in spring404. Thus, after removal of the tooling components, and with assembly400in an unloaded condition, spring404couples load beam406at a desired angle α with respect to baseplate402.

Another advantage realized by configuring a baseplate402with at least one integral anvil422is that precision placement of a tooling anvil408is no longer required to ensure bending of spring404at optimal bend location424. In an embodiment according to the invention, the bend location is determined according to the placement and formation of spring-forming edge430of integral anvil422. Bend location accuracy is therefore controllable by the baseplate forming and/or etching processes used to configure the integral anvil. The role of tooling anvil408is thus reduced to providing a stable mounting surface for baseplate402, and this allows for a much wider tolerance on placement of the tooling anvil.

Another advantage is that out-of-tolerance conditions in bend angle radius are far less likely, because each integral anvil is used only once in a bending operation. As a result, changes in the corner curvature of a tooling anvil are no longer an issue in quality control.

FIG. 5shows a magnified isometric view of an embodiment500of a baseplate502according to the invention assembled to a spring504and a load beam506. Assembly500includes integral anvils522, one on each side of baseplate502, corresponding to bridging areas514of spring504. Integral anvils522are formed for alignment of their spring-forming edges530coincident with the optimal bend location532, when spring504is bonded to baseplate502in a desired location. In this embodiment, the upper corners of integral anvils522comprise rounded corners534. Rounded corners534may be employed to provide a smoother fulcrum for the bend in location532to reduce the probability of spring fatigue or fracture during pre-load forming. This also reduced the probability of spring failure at the bend location during an excessive load condition such as a shock.

In the embodiments presented thus far, the integral anvils have been shown having a uniform thickness—the same thickness of the baseplate from which the integral anvil is formed. Additional embodiments are now disclosed wherein a portion of an integral anvil is configured with less thickness than the uniform thickness to achieve an additional manufacturing advantage.

FIG. 6shows a magnified isometric view of an embodiment of the invention, showing a baseplate602configured with an integral anvil622. In this embodiment, integral anvil622includes a relief area636comprising a rectangular channel running through the upper surface in a transverse direction parallel to spring-forming edge630. Relief area636may be formed by etching or precision machining. The purpose of relief area636is twofold. First, it lessens the total frictional force that acts against a spring (not shown) under tension during a bending operation as the spring is stretched across upper surface618and around corner634. Second, the elimination of friction beneath the portion of the spring covering relief area636allows that spring portion greater flexibility, thereby facilitating stretching and bending of the spring at a location adjacent to the optimal bend location when the spring is subject to rolling tool pressure. This creates greater uniformity in the thickness of the spring throughout the bend, resulting in a more resilient spring.

FIG. 7shows a magnified isometric view of another embodiment of a baseplate702according to the invention, this one having a relief area736etched or machined over the entire upper surface of integral anvil722to reduce its overall thickness. In this embodiment, the only contact between integral anvil722and its corresponding spring occurs at the junction of corner734and the optimal bend location. Many other embodiments of a baseplate according to the invention are possible, wherein the baseplate includes some configuration of one or more relief areas that create a portion of the integral anvil having less thickness than the uniform thickness of the baseplate.

FIG. 8illustrates an embodiment of a method800according to the invention for pre-loading a hard disk drive suspension assembly. These method steps may be deduced from the foregoing disclosure, and are presented in flowchart form for greater clarity. Additional method steps or limitations not expressly included within the flow chart may be similarly deduced from the foregoing disclosure.

Method800begins at step801, which comprises forming at least one integral anvil on a baseplate, such that the integral anvil extends in a longitudinal or distal direction toward the load beam end. Any appropriate forming technique may be used, such as stamping, cutting, and/or bending a baseplate from sheet metal using tooling such as a progressive forming die. In another implementation, step801may further comprise forming an integral anvil to position its distal edge at a location coincident with an optimal bend location on a spring, when the spring is attached to the baseplate a desired or predetermined location. The method then proceeds to step803. This step comprises forming a spring-forming edge on the integral anvil. In one example, this forming step comprises creating a rounded corner on a spring-forming edge of the integral anvil.

The next step805comprises positioning a desired, or optimal bend location on a spring to coincide with the spring-forming edge. Implied in this step is bonding or otherwise attaching the spring to the baseplate at a predetermined or desired location, such that the optimal bend location on the spring lines up with the spring-forming edge of the integral anvil. In the final step807, the suspension assembly is pre-loaded by forming a permanent bend in the spring by an appropriate tooling means. In one embodiment, this means comprises supporting the assembly by means of a tooling anvil, and applying pressure to the spring using a roller to bend the spring around the spring-forming edge of the integral anvil.

FIG. 9illustrates an embodiment of a method900according to the invention for manufacturing a baseplate for a hard disk drive suspension. The steps of method900are presented in flowchart form for greater clarity. Additional method steps or limitations not expressly included within the flow chart may be deduced from the foregoing disclosure.

Method900begins at step901, which comprises forming at least one integral anvil on a distal end of the baseplate, such that the integral anvil includes a spring-forming edge. Formation of the spring-forming edge may include any appropriate forming techniques such as cutting, shaping, stamping, or etching a baseplate, and may also include forming a rounded corner on the spring-forming edge. The next step903comprises bonding one portion of the spring to an upper surface of the baseplate so that a desired bend location coincides with the spring-forming edge. In another embodiment, a portion of the spring is bonded to a baseplate surface so that the spring lies between the baseplate and a roller contact point. In any of these embodiments, bonding may be effected by any means known in the art, e.g. by applying an adhesive, or by welding, riveting, fastening, etc. The next step905comprises bonding another portion of the spring to an upper surface of the load beam. In another embodiment, the other portion of the spring is bonded to a load beam surface so that both the baseplate and load beam lie substantially on a common side of the spring. The final step907comprises pre-loading the suspension assembly by forming a permanent bend in the spring by downward exerting pressure on the spring around the spring-forming edge.

Referring again toFIGS. 3-7, and additionally toFIG. 10, which is a partial cross-sectional side view of a baseplate1000of a suspension assembly300,400, and500, one problem that is associated with the formation of the various surfaces1050of the baseplate is that sharp and/or inconsistent die break edges1052and/or die roll edges1053can be created in the surfaces. These portions1054of the surface, e.g., the sharp and/or inconsistent die break edges and/or die roll edges, can be formed, for example, when the shape of the baseplate is cut from the sheet of material, e.g., stainless steel, a composite of Stainless steel, or a laminate material (see U.S. Pat. No. 6,572,984 to Brink, which is hereby incorporated by reference), or other material from which it is formed. The shape of the baseplate can be cut from the sheet of material using any of a variety of cutting device, e.g., a stamp or a die, which are known to individuals having ordinary skill in the art.

Rough portions1054, e.g., sharp and/or inconsistent die break edges1052and/or die roll edges1053, of the baseplate's surface1050, are disadvantageous because they have a roughness that can contact and scratch any of the following: other components, e.g., a spring304,404, and504, and/or a load beam306,406, and506, that are included in the suspension assembly300,400, and500, other components that are implemented during the fabrication process of the suspension assembly, and/or other components of the hard disk drive which includes the suspension assembly. This contact and scratching can result in the generation of debris1056, e.g., particulate matter, which can cause the hard disk drive that includes the suspension assembly to fail. As a result, most manufacturers inspect the surfaces of the suspension assembly components before installation of the suspension assembly into a hard disk drive. Sharp and/or inconsistent die break edges and/or die roll edges can be deburred using deburring processes, which are known to individuals having ordinary skill in the art, for example, soaking the baseplate for a period of time in an electrochemical deburring tank. However, vibratory, chemical, or electrochemical deburring of the die break edges and/or the die roll edges affects all of the baseplate surfaces, thus degrading other critical tolerances and edges required for other purposes.

A method for eliminating or reducing the effect of the rough portions1054, e.g., sharp and/or inconsistent die break edges1052and/or the die roll edges1053, of a baseplate's surfaces1050is to coin, i.e., to shape, the baseplate's surfaces1050after the baseplate is cut. Referring additionally to the perspective view shown inFIG. 11, a baseplate1000is coined by placing the baseplate in an insert1160that is included in a device1162referred to as a station. The insert has a contour1164that matches the desired contour of the baseplate.

Using the station1162, an operator can apply a force to the baseplate1000via a top part1166that is configured to press down onto the baseplate and cause the baseplate's surfaces1050that are adjacent to the insert1160to contact and push against the insert so the contour1058of the baseplate surface conforms to the contour1164of the insert, even if the initial contour of the baseplate surface differs from the insert's contour. Thus, the insert creates the final dimensions of the baseplate. As part of the coining process, the rough portions1054of the baseplate's surface1050can be reduced or eliminated. The coining process can be applied to any of the baseplate surfaces, even including the surface of an integral anvil322,422,522,622, and722having an edge330,430,530, and630for forming the permanent bend in the suspension assembly's spring304,404, and504. After the coining process, the baseplate1000is removed from the insert1160and station1162, and moved to the next processing step.

FIG. 12includes a flowchart1200that shows an example algorithm for manufacturing a baseplate1000that is to be included within a hard disk drive suspension assembly300,400, and500. The baseplate has a surface1050. The algorithm starts at step1270where the baseplate is formed in manner that can create a roughness in a portion1054of the baseplate's surface. The baseplate can be formed, for example, by cutting the shape of the baseplate from a sheet of material, e.g., stainless steel, a composite of stainless steel, or a laminate material. Next, at step1272, the surface of the baseplate is coined to reduce the roughness in the portion of the surface. The baseplate is placed in a station1162with the baseplate surface adjacent to an insert1160that is part of the station, and then, the station is used to apply force to the baseplate so the baseplate surface contacts and pushes against the insert causing the surface's contour1058to conform to the insert's contour1164.

FIG. 13shows various views of another example baseplate1300before the baseplate is coined. More specifically,FIG. 13includes a perspective view1374, a top plan view1376, and a cross-sectional side view along line A-A1378of the baseplate. Also,FIG. 13includes a magnified partial cross-sectional side view1380of the baseplate (see Detail B), which shows one of the baseplate's die break edges1352and die roll edges1353, and associated roughness1354in the baseplate's surface before coining.

Referring additionally toFIG. 14, the example baseplate1300fromFIG. 13is shown resting in an insert1460that is included in a station1462during the coining process. In particular,FIG. 14includes a top plan view1476of the baseplate within the insert, and a corresponding cross-sectional side view1478of the baseplate, the insert, and the station's top part1466along line C-C.FIG. 14also includes a magnified partial cross-sectional side view1480of the baseplate, insert, and top part (see Detail D), which shows the top part pressing down on the baseplate within the insert.

Referring additionally toFIG. 15, the example baseplate1300fromFIGS. 13 and 14is shown after the coining process is complete.FIG. 15includes a perspective view1574, a top plan view1576, a cross-sectional side view along line E-E1578, and a magnified partial cross-sectional side view1580of the coined baseplate (see Detail F). As shown in the magnified view, the roughness1354previously associated with the die break edge1352has been reduced as a result of the coining process.

Advantageously, by adding the processing step of coining the baseplate1000and1300of the hard disk drive suspension assembly300,400, and500, any roughness in one or more portions1054, e.g., sharp and/or inconsistent die break edges1052and1352and/or die roll edges1053and1353, of the baseplate's surface1050can be reduced and potentially eliminated. Thus, coined baseplates will have more consistently formed surfaces. Also, by coining the baseplates, the need for deburring a baseplate's surfaces can be eliminated, or the length of time spent deburring the baseplate's surfaces can be reduced. Accordingly, the step of coining the baseplates can result in increased product throughput, yield, and quality during manufacturing. Because the surfaces of the baseplate after coining are smoother in shape and more consistent formed, there is less of a likelihood that the surfaces will scratch other components, e.g., a spring304,404, and504, a load beam306,406, and506, load-unload ramps, and/or assembly combs, as are known to an individual having ordinary skill in the art, and create debris1056. Accordingly, coining the baseplate surfaces results in a reduction in the roughness of the baseplate's surfaces and a reduction in the amount of debris that ultimately reside within the disk drive that includes the coined baseplate.

While various embodiments of the invention have been illustrated and described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the spirit and scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.