JP3614268B2 - Flexure strain correction system for hard disk suspension - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for correcting a static roll angle or pitch angle of a flexure used in a suspension for a hard disk drive or the like.
[0002]
[Prior art]
In the hard disk drive suspension technology, as the capacity of the hard disk increases, it has become necessary to keep FH (Fly Height), which defines the clearance between the slider and the disk, at a constant low value. For this purpose, negative pressure sliders have been used and the accuracy of assembling work has been improved, but higher accuracy of flexures has been demanded. For example, Japanese Patent Application Laid-Open No. 55-22296 discloses a configuration in which dimples that strike a load beam are provided in a flexure and an access head is held so as to be displaceable in the roll and pitch directions. It is desired to further improve the above. In particular, when a small slider of the order of 1 (W) × 1.25 (L) × 0.3 (D) (mm) called a pico slider is used in recent years, the lift force obtained is small and the FH is stabilized. The problem is that it becomes more difficult.
[0003]
In such a hard disk suspension, the shape and dimensions of the flexure must be accurately controlled in order to suitably and stably control the fly height of the read / write head. When the flexure has a slight roll or pitch distortion, a torque acts on the slider, which adversely affects the stable control of the fly height. In particular, in the suspension manufacturing process, various parts are mounted on the load beam, and during that time various external forces are applied to the suspension, especially the flexure. In some cases, extremely tight tolerances such as ± 0.5 degrees cannot be satisfied. In particular, it is known that the effect of strain in the roll direction on fly height increases as the slider becomes smaller.
[0004]
Therefore, a method for compensating for flexure distortion by twisting a load beam is conventionally known. However, since the support load for the flexure also changes, a process for correcting the load is required again. The resonance characteristic, which is another important characteristic of the suspension, depends on the shape of the load beam. Therefore, the correction by the load beam adversely affects the resonance characteristics.
[0005]
[Problems to be solved by the invention]
In view of the problems of the prior art, a main object of the present invention is to provide an apparatus capable of correcting a roll angle of a flexure without applying a force to a load beam.
[0006]
A second object of the present invention is to provide an apparatus capable of easily correcting the roll angle of a flexure without causing problems such as a decrease in production efficiency during a normal manufacturing process.
[0007]
A third object of the present invention is to provide an apparatus capable of correcting a static pitch angle together with a roll angle.
[0008]
[Means for Solving the Problems]
According to the present invention, the above-described object has a flexure attached to the tip of the load beam, and supports the flexure with respect to the load beam through dimples provided in either part. An apparatus for correcting distortion of a flexure in a hard disk suspension comprising: a clamp portion that holds a base end portion of a load beam; one of one end of the flexure that is displaceable in an axial direction and a left-right direction A first correction rod arranged to abut against the surface of the flexure; a second correction rod arranged to abut on the other surface of the tip of the flexure and displaceable in the axial direction and the left-right direction; Means for driving the correction rods to apply a couple in the roll direction to the flexure by the correction rods; Means for detecting a linear displacement; means for detecting an axial load applied to the correction rod; and an axial direction of the correction rods so as to apply a couple to the flexure by the correction rods. This is achieved by providing a device characterized in that it comprises means for controlling the displacement.
[0009]
Since a pure couple can be applied to the flexure in this way, the distortion in the roll direction, that is, the static roll angle can be corrected without applying a load to the load beam or dimple.
[0010]
In addition to correcting the roll angle by applying a couple of forces to the left and right points of the flexure, the flexure that substantially aligns the first and second rods in the axial direction with respect to the dimple, respectively. If it is possible to move to a position where it should come into contact with the position of the tip of the flexure, it is possible to correct the pitch angle of the flexure by applying a load to the central portion of the flexure from only one side.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
FIG. 1 shows a typical flexure support structure to which the present invention is applied. One end of a flexible flexure 2 is joined to the free end of a relatively rigid load beam 1. An access head such as a magnetic head is fixed to the tongue 3 cut out by the flexure 2. The load beam 1 and the flexure 2 may be made of any metal material having appropriate characteristics, but are generally made of stainless steel (SUS). As shown in FIG. 2, the load beam 1 is provided with a spherical protrusion called a dimple 5 having a radius of about 0.25 mm, so that the head 4 can access the disk surface. The back surface of the flexure 3 is supported so as to allow the movement of the head 4 in the pitch direction (FIG. 2) and the movement in the roll direction (FIG. 3). However, the read / write position 6 of the access head is arranged on one side of the head 4, and the posture when the access head 4 is flying has a great influence on the FH. In particular, it is known that the movement of the access head in the roll direction has a great influence on FH.
[0013]
FIG. 4 is a perspective view schematically showing the apparatus according to the present invention, and an opening 10 a is provided in a fixed base 10. A clamp 12 for clamping the base end of the suspension, that is, the base end of the load beam 1, is provided behind the opening 10a, and the front end of the suspension, that is, the front end of the flexure 2 faces the opening 10a. The base end portion of the suspension is supported by the clamp portion 12.
[0014]
The pitch and roll angle of the suspension are normally measured at the load condition position, and the load condition is more stable against external force. Therefore, when the correction is made, the fixture 11 is kept at the load condition position as shown in FIG. ing.
[0015]
Above the opening 10 a, the correction rod 14 is attached to the Y-axis stage 18 via the load cell 16, and the Y-axis stage 18 can be displaced in the Y-axis direction, that is, the front-rear direction with respect to the Z-axis stage 20. On the other hand, the Z-axis stage 20 can be displaced in the vertical direction, that is, in the Z-axis direction with respect to the X-axis stage 22, and similarly, the X-axis stage 22 is shifted in the left-right direction with respect to a fixed frame such as a fixed stage mounting plate 24. It is supported so as to be displaceable in the X-axis direction.
[0016]
A structure similar to that described above is disposed on the lower side of the fixed base 10, and the correction rod 14 projects from the lower side of the opening 10 a so as to come into contact with the tip of the suspension 1.
[0017]
Further, a lens barrel 28 attached to the fixed column 26 is provided in front of this structure so that the position where the correction rod 14 contacts the flexure 2 can be accurately measured. That is, the lens barrel 28 is fixed so that the tip of the flexure can be enlarged and observed. Thereby, the lens barrel 28 is aimed at the dimple, and then the lens barrel 28 is displaced in the X-axis direction until the left and right correction rods 14 are aimed at the position where they abut against the flexure. The horizontal position can be obtained. Further, the axes of the upper and lower correction rods 14 are aligned, adjusted to the center of the dimple by the X-axis stage 22, and then the upper and lower X-axis stages 22 are moved in the directions opposite to each other by the same distance. Torque can be applied at the center.
[0018]
FIG. 6 shows the functional configuration of this apparatus. The amount of strain detected by the load cell 16 is sent to the AD converter 36 via the dynamic strain amplifier 34, and the digitized strain data is stored in the computer. 38. On the other hand, the displacement in the X direction and the Z direction of the correction rod 14 is also supplied to the computer 38 via the biaxial controllers 30 and 32.
[0019]
With such a configuration, the correction rods are arranged at approximately the same distance from the top and bottom of the flexure and in the left-right direction from the dimple, and each Z-axis stage is moved at the same speed. Can be twisted. As a result, it is possible to secure a desired permanent deformation path, that is, a correction amount, by giving the flexure a predetermined torsional displacement considering the springback of the flexure. In this case, it is preferable to make a table of permanent torsional deformation with respect to a given torsional displacement so that a desired amount can be corrected by a single correction operation. Further, at the time of measurement, the moment when the correction rod contacts the flexure can be detected as the time when the detection value of the load cell changes suddenly, and the displacement of the correction rod in the Z-axis direction can be controlled from that time.
[0020]
In this way, the static roll angle can be corrected by twisting the flexure in the roll direction without applying a load to the load beam. In addition, when it is necessary to correct by twisting in the opposite direction, the upper and lower correction rods may be exchanged in the left-right direction together with each X-axis stage. In order to correct the pitch angle of the flexure, as shown by an imaginary line in FIG. 4, the correction rod 14 'is disposed in front of the dimple and at a substantially horizontal center position of the flexure, and the flexure is viewed from either the top or bottom. Similarly, the static pitch angle can be corrected by giving a displacement to. In this case, it is inevitable that the force is applied to the load beam or dimple because the flexure cannot be twisted by a couple of forces, but in this case, the force is small and less than 1.5 gf. There will be no deformation in the beam. Further, at the time of correction, it is held at the load state position by the fixture, and the load value is at least 2.5 gf, so that the load beam does not move during the correction. When correcting the static pitch angle and the roll angle, the correction amount can be increased by blowing hot air on the deformed portion of the flexure.
[0021]
In addition, according to the present invention, the static roll angle and the static pitch angle can be individually corrected without affecting other portions. Therefore, in the existing production line as shown in FIG. After the various steps (ST1), the load is corrected as before (ST2), the static roll angle is corrected (ST3), and the static pitch angle is further corrected (ST3). Can be added. Therefore, it is possible to incorporate the correction process as it is in the production facility without affecting the tact time in the production line. Further, in the past, there was a restriction that a certain amount of correction could not be made due to a change in resonance characteristics. However, according to the present invention, since there is no such restriction, the manufacturing yield of the flexure or suspension can be improved. Can do.
[0022]
【The invention's effect】
In this way, it is possible to easily correct the distortion in the roll direction, that is, the static roll angle, without applying a load to the load beam, that is, the dimple, thereby simplifying the manufacturing process and improving the performance and performance of the hard disk. This can greatly contribute to reliability. Moreover, since it is possible to cope with a case where the correction amount is large, the manufacturing yield of the suspension can be improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a structure of a magnetic disk suspension to which the present invention is applied.
FIG. 2 is a longitudinal sectional view showing a main part of FIG.
3 is a cross-sectional view showing the main part of FIG. 1;
FIG. 4 is a schematic perspective view schematically showing an embodiment of a correction device according to the present invention.
FIG. 5 is an enlarged perspective view of a main part showing a state where a suspension is held at a load state position by a fixture.
6 is a diagram showing a functional configuration of the apparatus shown in FIG. 4; FIG.
FIG. 7 is a flowchart showing the relationship of the correction process to the suspension manufacturing process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Load beam 2 Flexure 3 Tongue piece 4 Head 5 Dimple 10 Fixed base 10a Opening 11 Fixture 12 Clamp part 14 Correction rod 16 Load cell 18 Y-axis stage 14 Inclination stage 20 Z-axis stage 22 X-axis stage 24 Stage mounting plate 26 Column 28 Tube

Claims (2)

Flexure strain in a hard disk suspension having a flexure attached to the tip of the load beam and supporting the flexure against the load beam through dimples provided at either of the two portions. A device for correcting
A clamp that holds the base end of the load beam;
A first correction rod disposed so as to be displaceable in an axial direction and a left-right direction and in contact with one surface of the tip portion of the flexure;
A second correction rod disposed so as to be displaceable in an axial direction and a left-right direction and to contact the other surface of the tip portion of the flexure;
Means for driving the two correction rods to provide a roll couple to the flexure by the two correction rods;
Means for detecting an axial displacement of the correction rod;
Means for detecting an axial load applied to the correction rod;
Means for controlling the axial displacement of the two correction rods so as to apply a couple to the flexure by the two correction rods. The first and second rods can be moved to positions where they should contact the position of the tip of the flexure which is substantially aligned with the dimple in the axial direction, and the flexure is corrected in the pitch direction by any one of them. The apparatus of claim 1, wherein the apparatus is capable of doing so.

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