Patent Publication Number: US-2020286510-A1

Title: Hard disk comb, actuator, and manufacturing method of hard disk comb

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2019-038457 filed Mar. 4, 2019, the contents of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a hard disk comb, an actuator, and a manufacturing method of the hard disk comb. 
     BACKGROUND 
     A hard disk drive (HDD) is known as a large-capacity magnetic recording medium, and is widely used by being mounted on a personal computer (PC) or the like. Generally, the hard disk drive includes a rotating magnetic disk and an actuator having an arm to which a magnetic head is attached. Since the position of the magnetic head relative to the magnetic disk changes as the arm swings, information can be read or written at a predetermined position on the magnetic disk. Japanese Unexamined Patent Application first Publication No. 2002-197821 discloses an example of such an actuator. 
     In addition, a comb may be used as a component of the actuator. The comb is a component to which a plurality of arms are fixed at predetermined intervals. 
     In the related art, as a hard disk comb, an arm has been formed by cutting. However, in recent years, it is required to make the arm thinner for the purpose of increasing the capacity of the HDD, and the arm may not be formed by cutting because a thickness is too thin, or even when the arm could be formed, dimensional accuracy may not be ensured. 
     SUMMARY 
     One or more embodiments of the present invention provide a hard disk comb capable of ensuring dimensional accuracy of an arm even in a case where a thickness of the arm is thin. 
     A hard disk comb according to one or more embodiments of the present invention includes a main body having a groove formed therein, and an arm joined to the main body, and a part of the arm is located inside the groove, and an opening edge of the groove and an upper surface of the arm are joined to each other. 
     According to one or more embodiments, the hard disk comb can be formed by forming the arm in advance by press working, for example, and fixing the arm to the main body. Therefore, dimensional accuracy of the arm can be ensured even when the thickness of the arm is thin, as compared with a case where the arm and the main body are integrally formed by cutting, for example. 
     Here, the arm may be formed in a plate shape having the upper surface and a lower surface, and among the upper surface and the lower surface, the only upper surface may be joined to the main body. 
     In addition, the arm and the main body may be joined to each other by welding, or may be joined by laser welding. 
     In these cases, each of the arms can be reliably joined to the main body even in a case where the gap between the arms is significantly small, by joining each of the arms in order from above or below. 
     In addition, at least three joining portions between the main body and the arm may be formed, and the three joining portions may not be disposed on a straight line. 
     In this case, since the joining portions are not disposed on a straight line, warpage of the arm due to the joining can be suppressed. 
     In addition, the arm may include an aluminum layer and SUS (Japanese Industrial Standards designation for stainless steel) layers provided on both surfaces of the aluminum layer, and the main body may be formed of SUS. 
     In this case, the arm and the main body can be welded by the SUS layer, and the aluminum layer is included, so that the weight of the arm can be reduced. 
     In addition, a gap may be provided between the arm and an inner surface of the groove. 
     In this case, the surface area of the main body increases and the volume of the main body decreases, as compared with the case where no gap is provided. As described above, the heat dissipation of the comb can be improved by increasing the surface area of the main body. In addition, the weight of the main body can be reduced by reducing the volume of the main body. 
     In addition, a part of the inner surface of the groove may be an inclined surface. And the inclined surface may face the arm with a gap interposed therebetween, the gap provided between the arm and the inner surface of the groove. 
     In this case, when the joining jig is inserted into the groove together with the arm during the manufacture of the hard disk comb, the inclined surface serves as a guide, and the manufacturing step can be further facilitated. 
     An actuator according to one or more embodiments of the present invention includes the hard disk comb, a suspension attached to a tip end portion of the arm, a magnetic head attached to the suspension, and a coil holding portion fixed to the main body, or integrally formed with the main body, and a coil held by the coil holding portion. 
     According to the actuator of one or more embodiments, the dimensional accuracy of the arm can be ensured even when the thickness of the arm is thin as described above, so that more arms and magnetic heads can be disposed in a small space. Therefore, it is possible to contribute to miniaturization and increase in capacity of the HDD. 
     A hard disk comb according to one or more embodiments of the present invention includes a main body having a groove formed therein; and an arm joined to the main body, wherein a part of the arm is located inside the groove, the arm has an aluminum layer and SUS layers provided on both surfaces of the aluminum layer, and the main body is formed of SUS. 
     According to one or more embodiments, the hard disk comb can be formed by forming the arm in advance by press working, for example, and fixing the arm to the main body. Therefore, dimensional accuracy of the arm can be ensured even when the thickness of the arm is thin, as compared with a case where the arm and the main body are integrally formed by cutting, for example. In addition, the arm and the main body can be welded by the SUS layer, and the aluminum layer is included, so that the weight of the arm can be reduced. 
     A manufacturing method of a hard disk comb according to one or more embodiments of the present invention includes preparing a main body having a groove formed therein, inserting an arm and a joining jig inside the groove, joining the arm and the main body, and extracting the joining jig from the groove. 
     By adopting such a manufacturing method, it is possible to fix the arm to the main body in a state where the surface of the arm is in close contact with the inner surface of the groove, while providing the gap between the inner surface of the groove and the arm. Therefore, the posture of the arm can be stabilized. 
     According to one or more embodiments of the present invention, it is possible to provide the hard disk comb capable of ensuring the dimensional accuracy of the arm even in a case where the thickness of the arm is thin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an actuator having a hard disk comb according to one or more embodiments. 
         FIG. 2  is a perspective view of the hard disk comb in  FIG. 1 . 
         FIG. 3  is a sectional view taken along a line III-III in  FIG. 2 . 
         FIG. 4A  is a view showing a manufacturing method of the hard disk comb according to one or more embodiments. 
         FIG. 4B  is a view showing a step following a step of  FIG. 4A . 
         FIG. 4C  is a view showing a step following the step of  FIG. 4B . 
         FIG. 5  is a plan view of the hard disk comb according to one or more embodiments, and shows a position of a joining portion between an arm and a main body. 
         FIG. 6  is a sectional view of a hard disk comb according to one or more embodiments. 
         FIG. 7A  is a view showing a manufacturing method of the hard disk comb according to one or more embodiments. 
         FIG. 7B  is a view showing a step following a step of  FIG. 7A . 
         FIG. 7C  is a view showing a step following the step of  FIG. 7B . 
         FIG. 8A  is a sectional view of a hard disk comb according to one or more embodiments. 
         FIG. 8B  is a view showing a manufacturing method of the hard disk comb according to one or more embodiments. 
         FIG. 9A  is a sectional view of a hard disk comb according to one or more embodiments. 
         FIG. 9B  is a view showing a manufacturing method of the hard disk comb of  FIG. 9A . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a hard disk comb (hereinafter, referred to as a “comb”) and an actuator including a comb according to one or more embodiments will be described with reference to the drawings. 
     As shown in  FIG. 1 , an actuator  1  according to one or more embodiments includes a comb  2 A, a suspension  3 , a magnetic head  4 , a coil holding portion  5 , and a coil  6 . The comb  2 A includes a main body  10  and a plurality of arms  20  (refer to  FIG. 2 ). An attachment hole  22  is formed in a tip end portion  21  of the arm  20 . The suspension  3  is attached to the attachment hole  22  of the arm  20 , and the magnetic head  4  is attached to the tip end portion of the suspension  3 . That is, the magnetic head  4  is fixed to the arm  20  via the suspension  3 . 
     The suspension  3  is formed of a plate material thinner than the arm  20 . The magnetic head  4  is an electronic component in which a recording head and a reproducing head are integrated. Although not shown, the suspensions  3  and the magnetic heads  4  are attached to the plurality of arms  20 , respectively. A plurality of magnetic heads  4  are in a state of floating with a small gap between a plurality of magnetic disks (not shown) inside the hard disk. 
     A pivot hole  11  is formed in the main body  10  of the comb  2 A, and the comb  2 A can swing around the pivot hole  11 . In one or more embodiments, a direction where a central axis O of the pivot hole  11  extends is referred to as a vertical direction. 
     The coil holding portion  5  is fixed to the main body  10  of the comb  2 A. A shape of the main body  10  can be appropriately changed, and for example, the coil holding portion  5  may be formed integrally with the main body  10 . 
     The coil  6  is an air-core coil in which a conductive wire material such as copper is aligned and wound. The coil  6  is hardened by a resin (not shown) so that an aligned and wound state is maintained. The coil  6  is held by the coil holding portion  5 . A pair of magnets  7  are disposed in the vicinity of the coil  6 . The coil  6  is interposed between the pair of magnets  7 .  FIG. 1  shows only one of the pair of magnets  7  for easy understanding. 
     The actuator  1  is configured such that when a current flows through the coil  6 , the main body  10  swings around the pivot hole  11 . When the main body  10  swings, a position of the magnetic head  4  with respect to the magnetic disk changes, so that information can be read or written at a predetermined position on the magnetic disk. 
     As shown in  FIG. 2 , the comb  2 A according to one or more embodiments includes one main body  10  and the plurality of arms  20 . Each of the arms  20  are formed in a plate shape having an upper surface  24  facing upward and a lower surface  25  facing downward (refer to  FIG. 3 ). Each of the arms  20  are fixed to the main body  10  and are disposed at intervals in the vertical direction. 
     As a material of the main body  10 , a metal such as SUS can be used. As a material of the arm  20 , one type of metal such as SUS or a multilayer material in which a plurality of types of metals are laminated can be used. As the multilayer material, for example, a structure in which a SUS layer is formed on both surfaces of an aluminum layer can be adopted. In a case where the multilayer material is used as the arm  20 , the upper surface  24  and the lower surface  25  of the arm  20  are formed of the SUS layer. 
     In the case where the multilayer material is used as the arm  20 , the material of each layer may be appropriately changed. In this case, the upper surface  24  and the lower surface  25  of the arm  20  are formed of a first material suitable for joining with the main body  10  and a second material having a lower density than that of the first material may be provided between two layers of the first material. 
     As shown in  FIG. 3 , a plurality of grooves  12  are formed in the main body  10  according to one or more embodiments. The plurality of grooves  12  are formed at intervals in the vertical direction. A base end portion  23  of the arm  20  is located inside the groove  12 . More specifically, the base end portion  23  is in contact with an upper inner surface  12   a , a bottom surface  12   b , and a lower inner surface  12   c  of the groove  12 . The base end portion  23  of the arm  20  is an end portion of the two end portions in a longitudinal direction of the arm  20  where the magnetic head  4  is not provided. Although not shown, the bottom surface  12   b  of the groove  12  is formed in an arc shape when viewed from the vertical direction. In addition, a surface of the base end portion  23  of the arm  20  that is in contact with the bottom surface  12   b  is also formed in the same arc shape as the bottom surface  12   b.    
     In one or more embodiments, the arm  20  is joined to the main body  10  in a state where the base end portion  23  of the arm  20  is inserted inside the groove  12 . Here, “joining” in this specification includes welding, deposition, and adhesion. As the welding, for example, laser welding can be adopted. As the deposition, for example, brazing can be adopted. The materials of the main body  10  and the arm  20  may be appropriately selected according to the type of joining. For example, in a case where laser welding is adopted, the material of the main body  10  and the material of the surface of the arm  20  may be of the same type. 
     Next, a manufacturing method of the comb  2 A according to one or more embodiments will be described with reference to  FIGS. 4A to 4C . 
     First, as shown in  FIG. 4A , the main body  10  having a plurality of grooves  12  formed therein is prepared. A forming method of the main body  10  can be appropriately selected, and for example, casting or cutting can be adopted. 
     Next, as shown in  FIG. 4B , the base end portion  23  of the arm  20  is inserted into the groove  12  located at the lowest position. The arm  20  and the main body  10  are joined to each other. An example of  FIG. 4B  shows a case where laser welding using laser beam L is adopted as the joining method. 
     In  FIG. 4B , the laser beam L is obliquely irradiated to the upper surface  24  of the arm  20 . 
     In addition, an irradiation position of the laser beam L is in the vicinity of an opening edge of the groove  12 . In  FIG. 4B , since the upper inner surface  12   a  of the groove  12  and an outer surface of the main body  10  are substantially perpendicular to each other, the irradiation position of the laser beam L is likely to be specified. By being irradiated with the laser beam L, the opening edge of the groove  12  and the upper surface  24  of the arm  20  are welded to each other. Although not shown in  FIG. 4B , the laser beam L is irradiated a plurality of times along the opening edge of the groove  12  at intervals. As a result, a plurality of joining portions P are provided for one arm  20  (refer to  FIG. 5 ). 
     As a result, the upper surface  24  of the arm  20  is joined to the main body  10 , and the arm  20  is fixed to the main body  10 . 
     Next, as shown in  FIG. 4C , the base end portion  23  of the other arm  20  is inserted into the adjacent groove  12 , and the other arm  20  and the main body  10  are joined to each other. By repeating this step, the comb  2 A is obtained. 
     In  FIGS. 4A to 4C , although the upper surface  24  of the arm  20  is joined to the main body  10 , the lower surface  25  of the arm  20  may be joined to the main body  10 . In this case, the base end portion  23  of the arm  20  is first inserted into the groove  12  located at the uppermost position, and the lower surface  25  of the arm  20  and the main body  10  are welded to each other. By sequentially joining the arms  20  to the adjacent grooves  12 , the comb  2 A is obtained. 
     Furthermore, among the upper surface  24  and the lower surface  25 , the only upper surface  24  may be jointed to the main body  10 . 
     As described above, the comb  2 A according to one or more embodiments includes the main body  10  having the groove  12  formed therein and the arm  20  joined to the main body  10 , and a part of the arm  20  is located inside the groove  12 , and the opening edge of the groove  12  and the upper surface  24  of the arm  20  are joined to each other. As a result, the comb  2 A can be formed by forming the arm  20  in advance by press working, for example, and fixing the arm  20  to the main body  10 . Therefore, dimensional accuracy of the arm  20  can be ensured even when the thickness of the arm  20  is thin, as compared with a case where the arm  20  and the main body  10  are integrally formed by cutting, for example. 
     In addition, the arm  20  may be formed in a plate shape having an upper surface  24  and a lower surface  25 , and among the upper surface  24  and the lower surface  25 , the only upper surface  24  may be jointed to the main body  10 . In this case, the joining portion P is easily visible, and it can be easily confirmed that the arm  20  and the main body  10  are joined to each other. 
     In  FIGS. 4A to 4C , the laser beam L is used. For example, after applying an adhesive to the inside of the groove  12  or the base end portion  23  of the arm  20 , the base end portion  23  is inserted into the groove  12 . Therefore, the arm  20  and the main body  10  may be joined by adhesion. Alternatively, both the upper surface  24  and the lower surface  25  of the arm  20  may be joined to the main body  10  by the laser beam L. However, in a case where the interval between the arms  20  is significantly small, one of the upper surface  24  and the lower surface  25  of the arm  20  may be joined to the main body  10  and the other is not joined to the main body  10 . The reason is that each of the arms  20  can be reliably joined to the main body  10  by joining each of the arms  20  in order from above or below, even in the case where the interval between the arms  20  is significantly small, as shown in  FIGS. 4A to 4C . 
     In addition, the number and shape of the joining portions P provided for one arm  20  can be changed as appropriate. 
     Here, in a case where welding is used as joining method, the joining portion P is cooled after being heated, and a residual stress is generated in the vicinity of the joining portion P, so that the arm  20  after joining may be warped. Such a warpage is likely to occur in a case where the linear joining portions P are formed on a straight line. The linear joining portions P may be joining portions that extend along the opening edge of the groove  12  and the upper surface  24  of the arm  20 . Therefore, for example, a plurality of dotted or linear joining portions P for one arm  20  may be disposed at intervals on a straight line. Alternatively, the linear joining portions P for one arm  20  may be formed so as to extend in a semicircular shape, for example, so that the linear joining portions P are not formed on a straight line. At least three joining portions P may be formed for one arm  20 , and the three joining portions P may not be disposed on a straight line. 
     The points P shown in  FIG. 5  indicate the position of the joining portions between the arm  20  and the main body  10  in one or more embodiments. As shown in  FIG. 5 , a plurality of joining portions P between the arm  20  and the main body  10  are provided according to one or more embodiments. Each joining portion P is dotted, not linear. In addition, the plurality of joining portions P are provided at intervals from each other, and are not disposed on a straight line. 
     As described above, the plurality of joining portions P are provided at intervals from each other and not disposed on a straight line, so that it is possible to more reliably suppress warpage of the arm  20  due to joining. 
     In addition, the arm  20  includes an aluminum layer and SUS layers provided on both surfaces of the aluminum layer, and the main body  10  may be formed of SUS. In this case, the arm  20  and the main body  10  can be welded by the SUS layer, and the weight of the arm  20  can be reduced by including the aluminum layer. 
     In addition, according to the actuator  1  of one or more embodiments, as described above, the dimensional accuracy of the arm  20  can be ensured even when the thickness of the arm  20  is thin, so that more arms  20  and the magnetic heads  4  can be disposed in a small space. Therefore, it is possible to contribute to miniaturization and increase in capacity of the HDD. 
     Next, one or more embodiments according to the present invention will be described, and the basic configuration is the same as that of the above-described embodiments. Therefore, the same components are denoted by the same reference numerals, a description thereof will be omitted, and only different points will be described. 
       FIG. 6  is a sectional view of the comb  2 B according to one or more embodiments. The position of the cross section corresponds to line III-III in  FIG. 2 . As shown in  FIG. 6 , according to one or more embodiments, a gap S is provided between the arm  20  and the inner surface of the groove  12 . 
     Next, a manufacturing method of the comb  2 B according to one or more embodiments will be described with reference to  FIGS. 7A to 7C . 
     First, as shown in  FIG. 7A , the arm  20  and a joining jig J are inserted inside the groove  12  of the main body  10 . At this time, the lower surface  25  of the arm  20  is in contact with the joining jig J. The portion of the joining jig J inserted inside the groove  12  has practically the same thickness as that of the gap S. Therefore, when the arm  20  and the joining jig J are inserted into the groove  12 , the upper surface  24  of the base end portion  23  of the arm  20  comes into surface contact with the upper inner surface  12   a  of the groove  12 . As a result, a posture of the arm  20  is set along the inner surface  12   a  of the groove  12 . In addition, the position of the arm  20  in the longitudinal direction is also determined by the base end portion  23  abutting against the bottom surface  12   b  of the groove  12 . By irradiating with the laser beam L in this state, the upper surface  24  of the arm  20  is joined to the main body  10 , and the arm  20  is fixed to the main body  10 . 
     The laser beam L is irradiated in the same manner as in the above-described embodiments. That is, the laser beam L is irradiated obliquely to the upper surface  24  of the arm  20 , and the irradiation position of the laser beam L is in the vicinity of the opening edge of the groove  12 . In  FIG. 7A , since the upper inner surface  12   a  of the groove  12  and the outer surface of the main body  10  are substantially perpendicular to each other, the irradiation position of the laser beam L is likely to be specified. The laser beam L is irradiated a plurality of times along the opening edge of the groove  12  at intervals, and the plurality of joining portions P are provided for one arm  20  (refer to  FIG. 5 ). 
     Next, as shown in  FIG. 7B , the joining jig J is extracted from the groove  12 . As a result, a gap S shown in  FIG. 6  is formed. 
     Next, as shown in  FIG. 7C , the arm  20  and the joining jig J are inserted into the adjacent grooves  12 , and the arm  20  and the main body  10  are joined to each other. 
     By repeating such steps, the comb  2 B according to one or more embodiments can be obtained. 
     In  FIGS. 7A to 7C , the upper surface  24  of the arm  20  is joined to the main body  10 , and the lower surface  25  of the arm  20  may be joined to the main body  10 . In this case, first, the base end portion  23  of the arm  20  and the joining jig J are inserted into the uppermost groove  12  in a state where the upper surface  24  of the arm  20  is in contact with the joining jig J. At this time, the lower surface  25  of the arm  20  comes into surface contact with the lower inner surface  12   c  of the groove  12 , and the base end portion  23  abuts against the bottom surface  12   b  of the groove  12 . Next, the lower surface  25  of the arm  20  and the main body  10  are welded to each other, and the joining jig J is extracted. 
     Similarly, the comb  2 B is obtained by sequentially joining the arms  20  to the adjacent grooves  12 . 
     As described above, in the comb  2 B according to one or more embodiments, the gap S is provided between the arm  20  and the inner surface of the groove  12 . As a result, the surface area of the main body  10  increases and the volume of the main body  10  decreases, as compared with the case where the gap S is not provided. As described above, the heat dissipation of the comb  2 B can be improved by increasing the surface area of the main body  10 . In addition, the weight of the main body  10  can be reduced by reducing the volume of the main body  10 . 
     In addition, in the manufacturing method of the comb  2 B according to one or more embodiments, the main body  10  having the groove  12  formed therein is prepared, the arm  20  and the joining jig J are inserted inside the groove  12 , the arm  20  and the main body  10  are joined to each other, and the joining jig J is extracted from the groove  12 . By adopting such a manufacturing method, it is possible to fix the arm  20  to the main body  10  in a state where the surface of the arm  20  is in close contact with the inner surface of the groove  12  while providing the gap S as described above. Therefore, the posture of the arm  20  can be stabilized. 
     Next, one or more embodiments of the present invention will be described, and the basic configuration is the same as that of the above-described embodiments. Therefore, the same components are denoted by the same reference numerals, a description thereof will be omitted, and only different points will be described. 
     As shown in  FIG. 8A , in the comb  2 C according to one or more embodiments, the lower inner surface  12   c  of the groove  12  is an inclined surface. The arm  20  is joined to the upper inner surface  12   a  of the groove  12  in a state where the base end portion  23  abuts against the bottom surface  12   b  of the groove  12 . An inclined surface  12   c  is disposed so as to face the lower surface  25  or the upper surface  24  of the arm  20  with the gap S interposed therebetween. 
       FIG. 8B  is a view showing a step in manufacturing the comb  2 C in  FIG. 8A . As shown in  FIG. 8B , when the joining jig J is inserted into the groove  12  together with the arm  20 , the inclined surface  12   c  serves as a guide, and the manufacturing step can be further facilitated. The joining jig J is formed with an inclined surface J1 that comes into surface contact with the inclined surface  12   c  when the joining jig J is inserted into the groove  12 . The other points are the same as those of the above-described embodiments, and a description thereof is omitted here. 
     The upper inner surface  12   a  of the groove  12  may be an inclined surface, and the arm  20  may be joined to the lower inner surface  12   c  of the groove  12 . 
     The technical scope of the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the spirit of the present invention. 
     For example, in the comb  2 C according to one or more embodiments, as shown in  FIG. 9A , the tip end of the inclined surface may have an edge shape. In  FIG. 9A , the arm  20  is joined to the upper inner surface  12   a  of the groove  12 , and the lower inner surface  12   c  of the groove  12  is an inclined surface. In addition, a lower inner surface  12   d  of another groove  12 A adjacent to the upper side of the groove  12  is also an inclined surface. The upper inner surface  12   a  of the groove  12  and the lower inner surface  12   d  of the other groove  12 A intersect at an acute angle. 
       FIG. 9B  is a view showing a step in manufacturing the comb  2 C in  FIG. 9A . As shown in  FIG. 9B , the laser beam L is irradiated to the tip end portion of the edge formed by the inner surface  12   a  of the groove  12  and the inner surface  12   d  of the other groove  12 A. In this case, the edge is easily melted by the heat of the laser beam L, the amount of welding is increased, and the joining strength can be further increased. 
     In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention, and the above-described embodiments and modification may be appropriately combined. 
     Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  . . . actuator 
               2 A- 2 C . . . hard disk comb 
               3  . . . suspension 
               4  . . . magnetic head 
               5  . . . coil holding portion 
               6  . . . coil 
               10  . . . main body 
               12  . . . groove 
               12   c  . . . inclined surface 
               20  . . . arm 
               21  . . . tip end portion 
               24  . . . upper surface 
               25  . . . lower surface 
             J . . . joining jig 
             P . . . joining portion 
             S . . . gap