Abstract:
A suspension for supporting a magnetic head is provided with a load beam formed of a thin-plate spring. A recess for accommodating a damper is formed in the load beam. The damper is affixed to a bottom surface of the recess.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a Divisional of U.S. application Ser. No. 12/704,712, filed Feb. 12, 2010 (now U.S. Pat. No. 8,161,626), which application is based upon and claims the benefit of priority from prior Chinese Patent Application No. 200910006550.3, filed Feb. 17, 2009, the entire contents of both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a load beam constituting a part of a suspension of a disk drive, suspension with the load beam, and a manufacturing method for the suspension. 
     2. Description of the Related Art 
     Conventionally, a magnetic disk device, such as a hard disk drive (HDD) or magneto-optical drive, comprises a magnetic head. The head flies above a magnetic disk rotating at high speed with a fine space therebetween. Data on the disk is read or written by the head. 
     An example of a suspension is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 10-162532 or 9-91909. 
     In recent years, the head size and flying height (above the disk surface) have been reduced with the development of disk devices with higher recording densities. In order to accurately read and write magnetic disk data, it is important to suppress vibration of a head portion, thereby precisely positioning the head. 
     As shown in  FIG. 10 , a disk drive with a suspension generally comprises a magnetic head  1 , a suspension  2  supporting the head  1 , a block  3  to which the suspension  2  is fixed, etc. The suspension  2  generally comprises a load beam  10  formed of a precise thin-plate spring, a baseplate  11 , a flexure  12  formed of a plate spring thinner than the load beam  10 , etc. The magnetic head  1  is located on a gimbal portion formed at the distal end of the flexure  12 . 
     A head portion comprising the magnetic head  1  receives vibration from a device for driving the head portion, a motor (not shown) for rotating a disk  13 , etc. Thus, the suspension  2  formed of a plate spring, may be deformed so that the magnetic head  1  is dislocated. This results in a read or write error. Thereupon, the damper  14 , such as the one shown in  FIG. 11 , may be used to reduce or remove vibration of the suspension  2 . The damper  14  is also referred to as a vibration damping member. The damper  14  comprises a metallic restrainer  15  and viscoelastic member  16  of a viscoelastic material, which are laminated thickness-wise. The damper  14  is affixed to the load beam  10  of the suspension  2 . 
     According to the suspension  2  with the damper  14 , the viscoelastic member  16  sandwiched between the vibrating suspension  2  and restrainer  15  is deformed as the suspension  2  vibrates. Molecular friction of the viscoelastic member  16  produces internal resistance, thereby converting vibrational energy into thermal energy. Thus, the vibrational energy directly received by the suspension  2  is greatly reduced, so that a vibration dumping effect can be obtained.  FIG. 12A  shows vibration characteristics observed before the damper  14  is affixed to the load beam  10 .  FIG. 12B  shows vibration characteristics observed after the damper  14  is affixed to the load beam  10 . As shown in  FIG. 12B , a damping effect obtained from the damper  14  affixed to the load beam  10  lowers the peak value of a gain in each vibration mode and provides the vibration damping effect. 
     As shown in  FIGS. 3A and 4A , transversely opposite side edge portions  10   a  of the load beam  10  are bent in order to enhance the rigidity of the load beam  10 . In this specification, the bending of the bent side edge portions  10   a  is referred to as “rib bending”. In order to maintain an appropriate flying height of the magnetic head  1  above the surface of the disk, moreover, a proximal portion  10   b  of the load beam  10  is slightly bent, as viewed laterally relative to the load beam  10 , as shown in  FIG. 4A . The proximal portion  10   b  is located near the block  3  and also functions as a hinge portion for warping the load beam  10  thickness-wise. In this specification, the bending of the proximal portion  10   b  is referred to as “load bending”. If the damper  14  is affixed to the load beam  10  before this load bending, it may undesirably interfere with a bending tool during the rib or load bending. In actual manufacturing processes, therefore, the damper  14  is affixed to the load beam  10  after the load beam  10  is bent, as shown in  FIGS. 9A to 9D . 
     In order to cause the viscoelastic member  16  to adhere closely to the load beam  10  in affixing the damper  14  to the load beam  10 , however, the damper needs to be pressed against the load beam  10  with a predetermined load. In some cases, the load beam  10  may be deformed by a pressing force on the damper  14  that is affixed to the bent load beam. If the load beam  10  is deformed, static properties, such as spring load, and dynamic properties, such as resonance, may vary. Variations of these properties impair the commodity value and working properties of the suspension. 
     If the damper is dislocated with respect to the load beam when it is affixed to the load beam, moreover, it may adversely affect the properties of the suspension. Conventionally, it is difficult to accurately position the damper, since the damper is affixed to the load beam formed of a flat thin-plate spring that carries no indication of a damper mounting position. 
     According to the conventional manufacturing processes in which the damper is affixed to the bent load beam, the opposite side edge portions  10   a  that are bent like ribs hinder the operation for affixing the damper  14 . Since one damper  14  is affixed to each load beam  10 , furthermore, the affixing operation is time-consuming, that is, work performance is poor. 
     Conventionally, the viscoelastic member is sometimes caused to project much from the periphery of the damper by the pressing force on the damper that is affixed to the load beam. In such a case, it is troublesome and difficult to thoroughly remove a projecting part of the viscoelastic member. In some cases, the periphery of the viscoelastic member is covered by a resin coating material after the damper is affixed to the load beam. In these cases, the usage of the coating material is too much to reduce the weight of the load beam. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the object of the present invention is to provide a load beam having stable properties such that it is less deformed by a damper affixed thereto, a suspension, and a manufacturing method for the suspension. 
     A load beam of the invention is formed of a thin-plate spring and constitutes a part of a suspension which supports a magnetic head, and a recess is formed in a part of the load beam so as to accommodate the damper. The recess may be formed by either partial etching or pressing. Alternatively, the recess may be formed by boring a through-hole greater than the damper in one of two plates which are superposed to each other to form the load beam. The depth of the recess should preferably be greater than the thickness of the damper. 
     A suspension according to the invention is the one which supports the magnetic head and comprises the above-described load beam, the damper being affixed to a bottom surface of the recess of the load beam. 
     In a method for manufacturing the suspension, the load beam is bent after the damper is affixed to the bottom surface of the recess of the load beam. 
     Further, the suspension manufacturing method described above may comprise fabricating a continuous load beam blank comprising a plurality of the load beams from a thin-plate spring material, forming the recess for accommodating the damper in each of the load beams of the load beam blank, affixing the damper to the bottom surface of the recess of each of the load beams, and bending each of the load beams after the damper is affixed thereto and separating the load beam from a scrap portion of the load beam blank. 
     According to the present invention, as described above, the recess greater than the damper is formed in the load beam, corresponding to a position where the damper is affixed. The damper is contained in the recess. Thus, the damper can be prevented from interfering with a bending tool even if the load beam is bent with the damper affixed thereto. Therefore, the damper can be affixed to the unbent flat load beam. Accordingly, the load beam cannot be easily deformed, so that the static and dynamic properties of the suspension can be prevented from varying. The recess should only be sufficiently large to accommodate the damper. In consideration of the work performance for the affixture of the damper to the load beam and the projection of the viscoelastic member, the recess should preferably be slightly larger than the damper. 
     The recess is formed by, for example, partial etching. Since the recess formed by partial etching can be used as a guide for the affixture of the damper, the damper can be easily positioned with respect to the load beam. 
     Since the damper can be affixed to the unbent flat load beam, moreover, the operation for affixing the damper can be easily automated. Since the damper can be affixed to each load beam of the continuous load beam blank that comprises a plurality of unbent load beams, in particular, the damper affixing operation can be automated with higher speed and accuracy and less deformation. In this case, the efficiency of the damper affixing operation can be further improved. 
     As the damper is pressed against and affixed to the load beam, a part of its viscoelastic member may sometimes be caused to project from the periphery of the restrainer. According to the present invention, however, the damper is contained in the recess, so that the projecting part of the viscoelastic member can be confined within a groove defined between the inner side surface of the recess and the side surface of the damper. Thus, the viscoelastic member can be prevented from projecting outside the load beam. Since the groove exists inside the recess, moreover, a coating material (e.g., resin) can be easily filled around the damper, and the usage of the coating material can be reduced. 
     Thus, according to the present invention, the damper is contained in the recess formed in the load beam. The weight of the load beam itself can be reduced by a margin corresponding to the recess. Consequently, an increase in weight attributable to the presence of the damper can be compensated with a reduction of the weight of the load beam, so that the suspension can be made lighter in weight. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1A  is a plan view of a conventional suspension; 
         FIG. 1B  is a plan view of a suspension according to one embodiment of the invention; 
         FIG. 2  is a partial sectional view typically showing a load beam and damper of the suspension shown in  FIG. 1B ; 
         FIG. 3A  is a sectional view of the suspension taken along line  3 A- 3 A of  FIG. 1A ; 
         FIG. 3B  is a sectional view of the suspension taken along line  3 B- 3 B of  FIG. 1B ; 
         FIG. 4A  is a sectional view of the suspension taken along line  4 A- 4 A of  FIG. 1A ; 
         FIG. 4B  is a sectional view of the suspension taken along line  4 B- 4 B of  FIG. 1B ; 
         FIG. 5A  is a sectional view showing how a viscoelastic member of a damper of the conventional suspension projects from the periphery of a restrainer; 
         FIG. 5B  is a sectional view showing how a viscoelastic member of a damper of the suspension according to the invention projects from the periphery of a restrainer; 
         FIG. 6A  is a sectional view showing how the periphery of the damper of the conventional suspension is covered by a coating material; 
         FIG. 6B  is a sectional view showing how the periphery of the damper of the suspension of the invention is covered by a coating material; 
         FIG. 6C  is a sectional view showing another example of the load beam of the suspension of the invention; 
         FIG. 7A  is a sectional view showing the load beam formed with a recess before bending work; 
         FIG. 7B  is a sectional view showing the load beam shown in  FIG. 7A  and the damper before affixture; 
         FIG. 7C  is a sectional view showing how the damper shown in  FIG. 7B  is affixed to the load beam; 
         FIG. 7D  is a sectional view showing the load beam and damper after rib bending; 
         FIG. 8A  is a plan view showing a load beam blank with recesses; 
         FIG. 8B  is a plan view showing how each load beam of the load beam blank shown in  FIG. 8A  is provided with the damper; 
         FIG. 9A  is a sectional view showing a conventional load beam before bending work; 
         FIG. 9B  is a sectional view showing the conventional load beam after the bending work; 
         FIG. 9C  is a sectional view showing the conventional load beam and the damper before affixture; 
         FIG. 9D  is a sectional view showing how the damper is affixed to the conventional load beam; 
         FIG. 10  is a perspective view showing a part of a disk drive; 
         FIG. 11  is a sectional view showing a part of the damper; 
         FIG. 12A  is a diagram showing vibration characteristics of a suspension without a damper; and 
         FIG. 12B  is a diagram showing vibration characteristics of a suspension with a damper. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of the present invention will now be described with reference to the accompanying drawings. 
       FIG. 1A  is a plan view of the suspension  2  comprising the conventional load beam  10 .  FIG. 1B  is a plan view of a suspension  2 ′ comprising a load beam  10 ′ according to the invention.  FIG. 2  is a sectional view typically showing the load beam  10 ′ and a damper  14  according to the invention. A recess  20  is formed in a part of the load beam  10 ′.  FIG. 3A  is an enlarged sectional view taken along line  3 A- 3 A of  FIG. 1A .  FIG. 3B  is an enlarged sectional view taken along line  3 B- 3 B of  FIG. 1B .  FIG. 4A  is an enlarged sectional view taken along line  4 A- 4 A of  FIG. 1A .  FIG. 4B  is an enlarged sectional view taken along line  4 B- 4 B of  FIG. 1B . 
     The load beam  10  shown in  FIG. 3A  is bent so that its transversely opposite side edge portions  10   a  rise like ribs. A central part of the conventional load beam  10  has a flat surface. In the load beam  10  shown in  FIG. 4A , the proximal portion  10   b  near the block  3  ( FIG. 10 ) is slightly bent. In the conventional load beam  10 , the damper  14  is affixed to the flat surface between the side edge portions  10   a.  Thus, in the conventional suspension  2 , the damper  14  projects to a height equal to its thickness above the flat surface of the load beam  10 . 
     As shown in  FIG. 3B , on the other hand, the load beam  10 ′ according to the present invention is formed with the recess  20  larger than the damper  14  in that part thereof on which the damper is located. The “recess greater than the damper” implies that the recess  20  is wider than the damper  14  when the load beam  10 ′ is viewed vertically from above ( FIG. 1B ). The damper  14  is contained in the recess  20 . The load beam  10 ′ is formed of a thin-plate spring. This thin-plate spring is a springy stainless-steel plate with a thickness of, for example, 50 to 100 μm. 
     As shown in  FIG. 4B , a proximal portion  10   b  of the load beam  10 ′ is slightly bent thickness-wise, as viewed laterally relative to the load beam. The proximal portion  10   b  is located near the block  3  and also functions as a hinge portion for warping the load beam  10 ′ thickness-wise. The recess  20  is formed in a region including this hinge portion (or proximal portion  10   b ). Thus, a part of the damper  14  is located in the hinge portion (or proximal portion  10   b ). 
     As shown in  FIG. 11 , the damper  14  comprises a metallic restrainer  15  and viscoelastic member  16 , which are laminated thickness-wise. The restrainer  15  is affixed to a bottom surface  20   a  of the recess  20  with the viscoelastic member  16  between them. As shown in  FIG. 2 , the upper surface of the restrainer  15 , that is, a surface  14   a  of the damper  14 , is located within the recess  20 . In other words, the surface  14   a  of the damper  14  does not project outside a surface  10   d  of the load beam  10 ′. 
     According to the load beam  10 ′ of the present embodiment, therefore, interference of a bending tool with the damper  14  can be avoided while the load beam with the damper  14  thereon is being bent. Thus, the load beam  10 ′ can be bent after the damper  14  is affixed thereto. In addition, the recess  20  can be used as a positioning guide in affixing the damper  14  to the load beam  10 ′. Accordingly, the damper  14  can be easily positioned with respect to the load beam  10 ′. 
     In affixing the damper  14  to the bottom surface  20   a  of the recess  20 , the damper  14  is pressed against the load beam  10 ′. By this pressing force, a part of the viscoelastic member  16  may sometimes be caused to project from the periphery of the restrainer  15 . In the case of the conventional suspension  2  shown in  FIG. 5A , a part  16   a  of the viscoelastic member projects much from the periphery of the restrainer  15  if the pressing force on the damper  14  is heavy. Thus, an operation is needed to remove the projecting part  16   a  of the viscoelastic member. 
     According to the load beam  10 ′ of the present invention, however, a groove  25  is formed between an inner side surface  20   b  of the recess  20  and the side surface of the restrainer  15 , as shown in  FIG. 5B . Thus, the part  16   a  of the viscoelastic member projecting from the periphery of the restrainer  15  is confined within the groove  25 . Consequently, the operation to remove the projecting part  16   a  of the viscoelastic member can be omitted. 
     Conventionally, as shown in  FIG. 6A , the side surface of the damper  14  is located outside the load beam  10 , so that a considerable amount of a coating material  30  is used to cover the side surface of the damper. 
     According to the suspension of the present invention, however, a coating material  30  is filled into the groove  25  between the inner side surface  20   b  of the recess  20  and the damper  14  after the damper  14  is affixed to the bottom surface  20   a  of the recess  20 , as shown in  FIG. 6B . Thereupon, the side surface of the damper  14  is covered by the coating material  30 . Thus, the usage of the coating material  30  can be reduced compared to the conventional case. 
       FIG. 8A  shows a load beam blank  41  comprising a plurality of load beams  10 ′ and scrap portions  40 . The load beam blank  41  is formed by, for example, etching. Each recess  20  should preferably be formed by partial etching as the load beam blank  41  is etched. Further, the recess  20  may be formed by pressing. 
     Alternatively, as shown in  FIG. 6C , each load beam  10 ′ may be formed by superposing two thin plates  50  and  51  on each other, and each recess  20  may be formed by boring a through-hole  52  greater than each damper  14  in the one plate  50 . 
     Each load beam  10 ′ is bent with the damper  14  affixed to the bottom surface  20   a  of the recess  20 . In order to avoid interference between the bending tool and damper  14 , a depth D 1  ( FIG. 2 ) of the recess  20  should preferably be made greater than a thickness T 1  of the damper  14 . In this embodiment, the recess  20  is formed in that one of the obverse and reverse surfaces of the load beam  10 ′ which is located opposite from a flexure  12 . Alternatively, however, the recess  20  may be formed in the same surface as the flexure  12 . 
     The following is a description of processes for manufacturing the suspension with the load beam  10 ′. As shown in  FIG. 7A , the recess  20  is formed in the load beam  10 ′ that is not yet bent. As shown in 
       FIG. 7B , thereafter, the damper  14  is opposed to the bottom surface  20   a  of the recess  20 . Then, the damper  14  is affixed to the bottom surface  20   a  of the recess  20 , as shown in  FIG. 7C . Thereafter, the rib bending and load bending of the load beam  10 ′ are performed by means of the bending tool, e.g., a die set (not shown). 
     According to this embodiment, the damper  14  is affixed to the unbent flat load beam  10 ′ ( FIGS. 7A to 7C ). Therefore, rib-like opposite side edge portions  10   a  can be prevented from interfering with a device for affixing the damper  14 . Thus, the operation for affixing the damper  14  to the load beam  10 ′ can be automated more easily than in the case of the conventional suspension  2  ( FIG. 1A ). 
     As shown in  FIG. 8A , the continuous load beam blank  41  comprising the plurality of load beams  10 ′ may be formed by etching. As shown in  FIG. 8B , in this case, the damper  14  should be affixed to the recess  20  of each load beam  10 ′ of the load beam blank  41 . By doing this, the damper affixing operation can be automated with higher speed and accuracy and less deformation, so that the operation efficiency can be further improved. 
     The present invention is not limited to the embodiment described herein, and its constituent elements may be embodied in various forms without departing from the scope or spirit of the invention. Further, the invention is also applicable to suspensions of other disk drives than hard disk drives. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.