Mold set for the load beam of a suspension for a disk drive

Abstract

To provide a mold set capable of avoiding an unstable distance between a load beam and a flexure.SOLUTION: A die 61 of a mold set 60 supports a first portion W1 of a work-piece. A pad 62 has a pressurized surface 65 sandwiching the work-piece with the die 61. A punch 63 pressurizes a second portion W2 of the work-piece in a thickness direction in a state in which the first portion W1 is sandwiched between the die 61 and the pad 62. The die 61 has: a support surface 70 that is flat and supports the workpiece; a first relief part 71; and a second relief part 72. The first relief part 71 is composed of a first slope 73. The second relief part 72 is composed of a second slope 74. The first slope 73 has a larger distance from the pad 62 as the first slope 73 approaches one side surface 61a of the die 61 from one end of the support surface 70 in a width direction. The second slope 74 has a larger distance from the pad 62 as the second slope 74 approaches another side surface 61b of the die 61 from another end of the support surface 70 in the width direction.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a mold set used when bending a load beam of a suspension for a disk device.

Background Art

[0002] A disk device is used in an information processing apparatus such as a personal computer. The disk device includes a magnetic disk that rotates about a spindle, a carriage that pivots about a pivot axis, and the like. A suspension for a disk device is provided on the arm of the carriage.

[0003] The suspension for a disk device includes a base plate, a load beam, a flexure disposed along the load beam, and the like. A slider is provided at a gimbal portion formed near the tip of the flexure. The slider is provided with elements for accessing data recorded on the disk, such as reading and writing. An example of a conventional suspension is described in Patent Document 1 or Patent Document 2.

[0004] The load beam is made of a metal plate such as stainless steel. The load beam has a substantially flat load beam main body portion and a pair of flange bending portions formed on both side portions of the load beam main body portion. The pair of flange bending portions extend in the length direction of the load beam respectively. These flange bending portions are formed by bending both side portions of the load beam at a substantially right angle in the thickness direction at the first bending portions respectively. As described in Patent Document 3, it is also known that a workpiece having a flange bending portion is slightly warped in the longitudinal direction when press-molded.

[0005] Depending on the specifications of the suspension, a second bending portion extending in the width direction of the load beam may be formed at the middle portion in the length direction of the load beam. The second bending portion may also be referred to as a sag bending portion. The second bending portion is formed by bending the middle portion in the length direction of the load beam at a slight angle (for example, about several degrees) in the thickness direction.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] When manufacturing the load beam, the flange bending portion is formed by a first mold set. After that, the second bending portion is formed by a second mold set. Although high precision is required for the load beam, when carefully inspecting the shape of the bent load beam, problems to be improved were found.

[0008] For example, when inspecting a cross-section along the width direction of a load beam having a pair of flange bending portions, there were no particular problems with the shape of the load beam before the second bending portion was formed. However, after the second bending portion was formed, it was found that deformation occurred where the flange bending portion bulged upward.

[0009] If the vicinity of the flange bending portion of the load beam is warped upward, problems occur in the assembled state where the flexure is disposed on the surface of the load beam. For example, the distance between the load beam and the flexure becomes non-uniform, causing non-uniform contact between the two. This is not preferable because it may adversely affect the gimbal movement of the flexure or generate minute metal particles due to the friction between the flexure and the load beam.

[0010] Accordingly, an object of the present invention is to provide a mold set for a load beam of a suspension for a disk device in which the shape of the load beam (particularly the cross-section in the width direction) is improved.

Means for Solving the Problems

[0011] One embodiment is a suspension for a disk device having a load beam and a flexure, wherein the load beam includes a load beam main body portion, a pair of flange bending portions each including a first bending portion formed on both side portions of the load beam main body portion, a second bending portion extending in the width direction of the load beam main body portion, a first cross-sectional portion, and a second cross-sectional portion.

[0012] Each of the flange bending portions extends in the length direction of the load beam main body portion. The second bending portion is formed between the flange bending portions. The first cross-sectional portion extends in the width direction of the load beam main body portion through a welding portion to which the flexure is to be fixed, and has a shape that warps upward as it approaches the flange bending portion. The second cross-sectional portion extends in the width direction of the load beam main body portion through a position different from the welding portion, and has a smaller height difference compared to the first cross-sectional portion.

[0013] A die set according to one embodiment includes a die, a pad, and a punch. The die supports a first portion of the workpiece in the length direction of the workpiece. The pad has a pressing surface that sandwiches the workpiece between the pad and the die. The punch presses a second portion of the workpiece in the thickness direction of the workpiece in a state where the first portion of the workpiece is sandwiched between the die and the pad.

[0014] The die has a flat support surface for supporting the workpiece, a first relief portion, and a second relief portion. The first relief portion consists of a first inclined surface, and the second relief portion consists of a second inclined surface. The first inclined surface increases in distance from the pad as it approaches one side surface of the die from one end of the support surface in the width direction. The second inclined surface increases in distance from the pad as it approaches the other side surface of the die from the other end of the support surface in the width direction.

[0015] In the die set of this embodiment, a first convex portion facing the first relief portion may be provided near one side portion of the pressing surface of the pad, and a second convex portion facing the second relief portion may be provided near the other side portion of the pressing surface. Further, a third relief portion consisting of a third inclined surface that increases in distance from the pad as it approaches the tip surface of the die may be provided at the tip of the die.

[0016] A method for manufacturing a load beam according to one embodiment forms the second bending portion by the die set. That is, in a state where the first portion of the workpiece is sandwiched between the die and the pad, a first gap is formed between the first inclined surface of the die and the workpiece, a second gap is formed between the second inclined surface of the die and the workpiece, and the second bending portion is formed by pressing the second portion of the workpiece in the thickness direction.

Advantages of the Invention

[0017] According to the mold set for the load beam according to the present invention, the distance between the load beam and the flexure is suppressed from varying, and the flexure and the load beam are prevented from contacting unstably.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0019] Hereinafter, a suspension for a disk device including a load beam according to one embodiment (hereinafter simply referred to as a suspension) will be described with reference to FIGS. 1 to 10. The disk device (hard disk device) 1 shown in FIG. 1 includes a case 2, a disk (magnetic disk) 4 that rotates about a spindle 3, a carriage 6 that pivots about a pivot shaft 5, and a positioning motor 7 that pivots the carriage 6. The case 2 is sealed by a lid (not shown).

[0020] FIG. 2 is a cross-sectional view schematically showing a part of the disk device 1. An arm 8 is provided on the carriage 6. A suspension 10 is attached to the tip of the arm 8. Near the tip of the suspension 10, a slider 11 that constitutes a magnetic head is provided. When the disk 4 rotates, an air bearing is formed between the disk 4 and the slider 11. The slider 11 is provided with an element for recording data on the disk 4 and an element for reading data recorded on the disk 4.

[0021] FIG. 3 is a plan view showing an example of the suspension 10. The suspension 10 includes a base plate 15, a load beam 16, a flexure 20, etc. The slider 11 is disposed at the tip of the flexure 20. The boss portion 15a of the base plate 15 is fixed to the arm 8 (shown in FIGS. 1 and 2) of the carriage. The load beam 16 is made of a stainless steel plate.

[0022] As shown in FIG. 3, the flexure 20 includes a portion 21 that overlaps the load beam 16, a flexure tail 22 that extends behind the base plate 15, etc. The flexure tail 22 includes a tail pad portion 22a. Terminals (tail electrodes) 25 to which electronic devices such as an amplifier are connected are disposed on the tail pad portion 22a.

[0023] The flexure 20 includes a metal base 30 (partially shown in FIG. 3) made of a stainless steel plate thinner than the load beam 16, and a wiring portion 31 disposed along the metal base 30. The metal base 30 of the flexure 20 is fixed to the load beam 16 by welding portions 32, 33 such as laser spot welding.

[0024] One embodiment of the load beam 16 will be described below. The load beam 16 shown in FIG. 4 includes a substantially flat load beam body portion 40, flange bending portions 43, 44 each formed by first bending portions 41, 42 formed on both sides of the load beam body portion 40, and a second bending portion 50 extending in the width direction of the load beam body portion 40. The double-headed arrow X1 in FIG. 4 indicates the length direction of the load beam 16, and the double-headed arrow Y1 indicates the width direction of the load beam 16.

[0025] The flange bending portions 43, 44 formed by the first bending portions 41, 42 each extend in the length direction of the load beam 16. The second bending portion 50 extends in the width direction of the load beam 16. The second bending portion 50 is formed by bending the middle portion of the load beam body portion 40 in the thickness direction.

[0026] A stepped portion 52 is formed between the tip portion 51 of the load beam 16 and the load beam body portion 40. In this specification, the side closer to the tip portion 51 with the second bending portion 50 as a boundary may be referred to as the "front side of the load beam", and the side farther from the tip portion 51 may be referred to as the "rear side of the load beam". An opening 53 is formed in the load beam body portion 40.

[0027] As shown in FIG. 3, the load beam 16 and the flexure 20 are fixed to each other by welding portions 32, 33 such as laser spot welding. The welding portions 32, 33 are formed between a pair of flange bending portions 43, 44. As shown in FIG. 4, the welding portions 32, 33 are separated from each other by a distance L1 in the width direction of the load beam 16. Moreover, the welding portions 32, 33 are separated from the second bending portion 50 by a distance L2 toward the rear side of the load beam 16.

[0028] FIG. 5 shows the results of detecting the height of each of two cross-sections (the first cross-section portion 55 and the second cross-section portion 56) along the width direction of the load beam 16 by a detector. The horizontal axis in FIG. 5 is the position in the width direction, and the vertical axis is the height.

[0029] As shown by line A1 in Fig. 5, the height of the surface of the first cross-sectional portion 55 along the F1-F1 line in Fig. 4 is indicated. The first cross-sectional portion 55 passes through the welded portions 32 and 33 and extends in the width direction of the load beam 16. Since the double-headed arrow X2 in Fig. 5 corresponds to the region of the opening 53, the height is not detected.

[0030] As shown by line A1 in Fig. 5, the first cross-sectional portion 55 has a shape that warps upward as it approaches the flange bending portions 43 and 44. The first cross-sectional portion 55 has a large height difference compared to the second cross-sectional portion 56. The load beam 16 and the flexure 20 are fixed to each other via the welded portions 32 and 33. Therefore, even if the height difference of the first cross-sectional portion 55 is large, the distance between the load beam 16 and the flexure 20 does not become unstable.

[0031] As shown by line A2 in Fig. 5, the height of the surface of the second cross-sectional portion 56 along the F2-F2 line in Fig. 4 is indicated. The second cross-sectional portion 56 passes through a position different from the welded portions 32 and 33 (the front side of the welded portions 32 and 33) and extends in the width direction of the load beam along the second bending portion 50.

[0032] As shown by line A2 in Fig. 5, the second cross-sectional portion 56 has a small change in height (within 2 to 3 μm) compared to the first cross-sectional portion 55 and is substantially flat. Therefore, in the assembled state where the load beam 16 and the flexure 20 are fixed to each other, the variation in the distance between the load beam 16 and the flexure 20 is small. For this reason, it is avoided that the load beam 16 and the flexure 20 come into contact unstably.

[0033] The two-dot chain line A3 in Fig. 5 indicates the height of the cross-section of the load beam of the comparative example (corresponding to the second cross-sectional portion 56 of the present embodiment). This comparative example is a case where the second bending portion 50 is bent using a conventional die. As shown by the two-dot chain line A3 in FIG. 5, the cross section of the comparative example greatly warps upward as it approaches the flange bending portions 43 and 44, and the height of the warpage exceeds 5 μm. Therefore, in the assembled state where the load beam and the flexure are fixed to each other, the variation in the distance between the load beam and the flexure is large, and the load beam and the flexure may come into contact unstably.

[0034] Hereinafter, the mold set 60 used when manufacturing the load beam 16 of the present embodiment and the manufacturing method of the load beam 16 will be described. FIG. 6 shows an intermediate product (referred to as work W) during the manufacture of the load beam 16. The work W before bending is flat. The length direction of the work W corresponds to the length direction of the load beam 16 (indicated by the double-headed arrow X1 in FIG. 5). The width direction of the work W corresponds to the width direction of the load beam 16 (indicated by the double-headed arrow Y1 in FIG. 5).

[0035] FIG. 7 shows the work W in which the flange bending portions 43 and 44 are formed by the first bending process. In the first bending process, the both side portions of the work W are bent substantially at right angles by a mold, whereby the flange bending portions 43 and 44 composed of the first bending portions 41 and 42 are formed. Further, the tip portion 51 of the load beam 16 is formed by pressing, and the step portion 52 is formed.

[0036] In the second bending process, the intermediate portion in the length direction of the work W having the flange bending portions 43 and 44 is bent using the mold set 60 described below, whereby the second bending portion 50 is formed. The work W includes a first portion W1 corresponding to the rear side of the load beam 16 and a second portion W2 corresponding to the front side of the load beam 16 with the second bending portion 50 as a boundary.

[0037] FIG. 8 shows the mold set 60 used when bending the second bending portion 50. FIG. 9 is a cross-sectional view of the mold set 60 and the work W. FIG. 10 is a cross-sectional view of the mold set 60 and the work W along the line F10-F10 in FIG. 9.

[0038] The mold set 60 has a die 61, a pad 62, and a punch 63 (shown by a two-dot chain line in FIG. 9). The first part W1 of the work W is placed on the die 61. The pad 62 is disposed above the die 61 and moves vertically by a drive mechanism. A pressing surface 65 is formed on the lower surface side of the pad 62. The pressing surface 65 is flat and extends in the horizontal direction.

[0039] In the second bending process, as shown in FIGS. 9 and 10, the first part W1 of the work W is sandwiched between the die 61 and the pad 62. In this state, when the punch 63 moves in the direction indicated by the arrow Z1 (shown in FIG. 9) by the drive mechanism, a second bending portion 50 is formed between the first part W1 and the second part W2 of the work W.

[0040] The upper surface of the die 61 has a flat support surface 70 extending in the horizontal direction and relief portions 71, 72 formed on both sides of the support surface 70. The first relief portion 71 consists of a first inclined surface 73. The first inclined surface 73 extends in the front-rear direction of the die 61 along one side surface 61a of the die 61. The second relief portion 72 consists of a second inclined surface 74. The second inclined surface 74 extends in the front-rear direction of the die 61 along the other side surface 61b of the die 61.

[0041] The first inclined surface 73 has a downward gradient from one end in the width direction of the support surface 70 toward one side surface 61a of the die 61. That is, the first inclined surface 73 is inclined such that the distance from the pressing surface 65 of the pad 62 increases as it approaches one side surface 61a of the die 61. The second inclined surface 74 has a downward gradient from the other end in the width direction of the support surface 70 toward the other side surface 61b of the die 61. That is, the second inclined surface 74 is inclined such that the distance from the pressing surface 65 of the pad 62 increases as it approaches the other side surface 61b of the die 61.

[0042] As shown in FIG. 10, the first inclined surface 73 is formed over a width L3 from one end of the support surface 70 of the die 61 toward one side surface 61a. The second inclined surface 74 is formed over a width L4 from the other end of the support surface 70 of the die 61 toward the other side surface 61b. It is desirable that the starting points 73a, 74a (the boundaries with the support surface 70) of these inclined surfaces 73, 74 be near the positions P1, P2 where the warping begins to increase in the cross section of the load beam of the comparative example shown by the two-dot chain line A3 in FIG. 5.

[0043] The first inclined surface 73 and the second inclined surface 74 each consist of an arcuate curved surface whose distance from the pressure surface 65 increases as it approaches the side surfaces 61a, 61b of the die 61. However, the inclined surfaces 73, 74 may each be an inclined surface whose height decreases linearly from the support surface 70 toward the side surfaces 61a, 61b of the die 61.

[0044] As shown in FIG. 10, the depths L5, L6 of the relief portions 71, 72 are greater than the amount of upward warping of the load beam of the comparative example shown by the two-dot chain line A3 in FIG. 5. The depths L5, L6 of the relief portions 71, 72 are greater than the thickness T1 of the work W (shown in FIG. 10), and preferably are more than twice the amount of upward warping of the load beam of the comparative example shown by the two-dot chain line A3 in FIG. 5. The widths L3, L4 of the relief portions 71, 72 are greater than the depths L5, L6 of the relief portions 71, 72. The widths L3, L4 of the relief portions 71, 72 are, for example, from 5 to 10 times the depths L5, L6 of the relief portions 71, 72.

[0045] As shown in FIG. 10, when the first portion W1 of the work W is sandwiched between the support surface 70 of the die 61 and the pressure surface 65 of the pad 62, a first gap G1 is formed between the first inclined surface 73 and the work W. Also, a second gap G2 is formed between the second inclined surface 74 and the work W.

[0046] In a state where the first part W1 of the workpiece W is sandwiched between the die 61 and the pad 62, the punch 63 (shown in FIG. 9) moves in the direction indicated by the arrow Z1. The second part W2 of the workpiece W is pressed in the thickness direction of the workpiece W by the punch 63, so that the second part W2 of the workpiece W bends. Thus, a second bending portion 50 is formed between the first part W1 and the second part W2.

[0047] After the second bending portion 50 is formed, the punch 63 moves away from the second part W2 of the workpiece W. When the punch 63 moves away from the second part W2, the workpiece W tries to return to its original shape due to some springback. However, the first part W1 of the workpiece W is constrained between the support surface 70 of the die 61 and the pressing surface 65 of the pad 62. Since the relief portions 71, 72 are formed on both sides of the support surface 70, the vicinity of the flange bending portions 43, 44 is not constrained. After the second bending portion 50 is formed under such a state, the punch 63 moves away from the workpiece W.

[0048] Since the die 61 of the mold set 60 of the present embodiment has the relief portions 71, 72 formed by the inclined surfaces 73, 74 with a downward gradient on both sides of the support surface 70, gaps G1, G2 are formed in the vicinity of the flange bending portions 43, 44. By forming the second bending portion 50 using the die 61 having such relief portions 71, 72, it was possible to avoid the phenomenon that the second cross-sectional portion 56 warps upward in the vicinity of the flange bending portion as shown by the line A2 in FIG. 5.

[0049] As described above, the manufacturing method of the load beam 16 of the present embodiment includes a first bending step and a second bending step. (1) In the first bending step, flange bending portions 43, 44 composed of first bending portions 41, 42 are formed on both side portions of the workpiece W. (2) After the first bending process is performed, the second bending process is performed. In the second bending process, a first portion W1 in the length direction of the work W on which the flange bending portions 43 and 44 are formed is sandwiched between the support surface 70 of the die 61 and the pressing surface 65 of the pad 62. When the work W is sandwiched between the die 61 and the pad 62, a first gap G1 is formed between the first relief portion 71 and the work W, and a second gap G2 is formed between the second relief portion 72 and the work W. (3) With the work W sandwiched between the die 61 and the pad 62, the second portion W2 of the work W is pressed in the thickness direction by the punch 63, whereby the second bending portion 50 is formed. Immediately thereafter, the punch 63 separates from the work W.

[0050] FIG. 11 shows a mold set 60A according to the second embodiment. The mold set 60A of the present embodiment also includes a die 61A and a pad 62A. A third relief portion 80 is formed at the tip of the die 61A, that is, at a location that serves as a fulcrum when bending the second bending portion 50. The length L7 of the third relief portion 80 is 10 times or more the thickness of the work. The third relief portion 80 consists of a third inclined surface 81. The third inclined surface 81 extends in the width direction of the die 61A. The distance of the third inclined surface 81 from the pressing surface 65 of the pad 62A increases as it approaches the tip surface 82 of the die 61A from the support surface 70 of the die 61A.

[0051] The pad 62A shown in FIG. 11 has a convex portion 90 facing the first relief portion 71 near one side portion of the pressing surface 65. A convex portion 91 facing the second relief portion 72 is provided near the other side portion of the pressing surface 65. These convex portions 90 and 91 have shapes corresponding to the inclined surfaces 73 and 74 of the relief portions 71 and 72. Regarding the other configurations and operations, since the mold set 60A of the second embodiment is common to the mold set 60 (shown in FIGS. 8 to 10) of the first embodiment, common reference numerals are given to the common portions of both, and the description is omitted.

[0052] In practicing the present invention, it goes without saying that various modifications can be made, such as the specific shapes and configurations of the load beam and flexure that constitute the suspension, as well as the dies, pads, punches, etc. that constitute the mold set.

Explanation of Reference Numerals

[0053] 10… Suspension for disk device, 16… Load beam, 20… Flexure, 32, 33… Weld portion, 40… Load beam main body portion, 41, 42… First bending portion, 43, 44… Flange bending portion, 50… Second bending portion, 55… First cross-sectional portion, 56… Second cross-sectional portion, W… Workpiece, W1… First portion, W2… Second portion, 60, 60A… Mold set, 61, 61A… Die, 61a… One side surface, 61b… The other side surface, 62, 62A… Pad, 63… Punch, 65… Pressing surface, 70… Support surface, 71… First relief portion, 72… Second relief portion, 73… First inclined surface, 74… Second inclined surface, 80… Third relief portion, 81… Third inclined surface, 90, 91… Protrusion.

Claims

1. A die set for bending a workpiece for a load beam having a pair of flange bending portions, a die supporting a first longitudinal portion of the workpiece; A pad having a pressure surface for sandwiching the workpiece between the pad and the die; a punch that presses a second portion of the workpiece in a thickness direction of the workpiece while the first portion of the workpiece is sandwiched between the die and the pad; The die is A flat support surface for supporting the workpiece; a first recess portion having a first slope whose distance from the pad increases as the first recess portion approaches one side surface of the die from one end in the width direction of the support surface; a second recess portion having a second inclined surface that increases in distance from the pad as it approaches the other side surface of the die from the other end of the support surface in the width direction; 13. A die set for a load beam comprising:

2. 2. The mold set according to claim 1, A mold set characterized in that the pad has a first convex portion opposite the first recess near one side of the pressure surface, and a second convex portion opposite the second recess near the other side of the pressure surface.

3. The mold set according to claim 1 or 2, A mold set characterized in that the tip of the die has a third escape portion consisting of a third inclined surface whose distance from the pad increases as it approaches the tip surface of the die.

Images