Abstract:
A low mass baseplate for attaching a suspension load beam to an actuator arm has a planar portion weld-attachable to a load beam base and a cylindrical boss portion attachable to an actuator arm, the planar portion is locally relieved to reduce mass while maintaining the baseplate effectiveness at the load beam spring portion. The baseplate relief is specially sized and configured to be free of entanglements during tumble deburring operations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application Ser. No. 60/197,794, filed Apr. 14, 2000. 
     Statement Regarding Federally Sponsored Research or Development 
     Not Applicable 
     Reference to a Microfiche Appendix 
     Not Applicable 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to mount baseplates for mounting load beams to actuator arms in disk drive suspensions, and more particularly to an improved mount baseplate having reduced mass while maintaining a thickness desirable for mechanical properties, the mass reduction being made at performance-noncritical areas of the baseplate. 
     2. Description of the Related Art 
     Typically a disk drive suspension comprises a steel load beam having a base section that is weld-attached to a mount comprising a baseplate. The baseplate is attached to the drive actuator arm such as by swaging the baseplate boss into engagement with an aperture in the arm. Typical thicknesses of the 0.200 by 0.200 inch planar portion of the, baseplates are in the range of 0.004 inch at a minimum to 0.008 inch that is currently preferred. The lower thicknesses may not provide adequate mechanical properties. Since the area is reasonably unchangeable, reducing the baseplate mass has centered on reduced thickness in the planar portion, but thicknesses are presently at the minimum. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention, therefore, to provide for use in disk drive suspensions an improved baseplate that has reduced mass but that maintains the desired thickness for mechanical properties. It is a further object to contour the common baseplate in areas not critical to performance to reduce mass without undue loss in mechanical properties. Yet another object is to provide a novel shape in a baseplate that accommodates all mechanical requirements, such as maintaining the base plate edge at the load beam spring section, keeping a minimum thickness or greater, and providing distributed welding sites, while having a reduced mass. 
     These and other objects of the invention to become apparent hereinafter are realized in a low mass baseplate for attaching a suspension load beam having a rigid section, a spring section and a base section by its the base section to an actuator arm, the baseplate comprising a planar portion attachable to the load beam base and integrally formed therewith a boss portion attachable to an actuator arm, the planar portion having a front edge and a rear edge and left and right lateral edges therebetween, the boss portion comprising a cylinder spaced inwardly from the planar portion edges and having a given outside diameter, the planar portion having a front edge recess in mass reducing relation, the recess defining with the left and right edges respectively left and right legs, the legs having a lateral extent greater than the boss portion outside diameter, whereby adjacent baseplates do not become entangled with each other in tumble deburring operations. 
     In this and like embodiments, typically, the left and right leg portions define left and right front edges, the edges being adjacent left and right spring areas respectively of the load beam spring section, the baseplate rear edge and the left and right lateral edges are radiused at their intersection in mass reducing relation, and the baseplate rear edge comprises a smooth curve commencing at the center of the rear edge and terminating on the left and right lateral edges of the planar portion at left and right points opposed across the boss. 
     Typically, the planar portion and the load beam base section are welded to each other at laterally and longitudinally distributed points between the most rearward part of the boss and the planar portion front edge. 
     Preferably, the recess is V-shaped with its open mouth adjacent the load beam spring section, or the recess has the shape of the interior opening in a U with its open mouth adjacent to the load beam spring section. 
     In a further embodiment, the invention provides a low mass baseplate for attaching a suspension load beam having a rigid section, a spring section and a base section by its the base section to an actuator arm, the baseplate comprising a metal planar portion weld-attachable to the load beam base and integrally formed therewith a cylindrical boss portion attachable to an actuator arm, the planar portion having a front edge and a rear edge and left and right lateral edges therebetween, the boss portion comprising a cylinder spaced inwardly from the planar portion edges and having a given outside diameter, the planar portion having a distal front edge recess coaxial with the boss portion and spaced therefrom, the recess being devoid of metal in mass reducing relation, the recess defining with the left and right edges respectively left and right legs, the legs having a lateral extent greater than the boss portion outside diameter, whereby juxtaposed baseplates do not become entangled with each other in tumble deburring operations. 
     In this and like embodiments, typically, the low mass baseplate planar portion recess has an extent along its lateral axis greater than its extent normal to the lateral axis, the recess terminates inwardly in a pointed or radiused terminal, the left and right leg portions define left and right front edges, the edges being adjacent left and right spring section areas respectively of the load beam spring section, the baseplate rear edge and the left and right lateral edges are radiused at their intersection in mass reducing relation, and the baseplate rear edge comprises a smooth curve commencing at the center of the rear edge and terminating on the left and right lateral edges of the planar portion at left and right points opposed across the boss. 
     The invention further provides in combination, the low mass baseplate described and a load beam having a base section, the baseplate planar portion being weld-attached to the load beam base section at laterally and longitudinally distributed points between the most rearward part of the boss and the planar portion front edge. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention will be further described in conjunction with the attached drawings in which: 
     FIG. 1 is an oblique view of the invention baseplate and load beam; 
     FIG. 2 is a top plan of thereof; 
     FIG. 3 is a side elevation view thereof; 
     FIG. 4 is a view like FIG. 2 of an alternative embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The great need for a low-mass baseplate mount design arises in part from the disk drive industry conversion to the pico form factor and in part from the simultaneous introduction of increased shock resistance requirements. All new disk drive programs will require a new level of baseplate mass as shock resistance characteristics become more critical, and as all future designs are critically evaluated to be sure no factor affecting performance is overlooked. The mass of the baseplate becomes critical as the total suspension mass becomes critical. The possibility of further reduction in the baseplate planar portion, or flange, thickness and hence of the mass is nonexistent since as the flange is already as low as 0.006 inches commonly and sometimes as little as 0.004 inches. Further reductions in flange thickness will compromise the purpose of the flange: to provide a stable and rigid base for the suspension spring section and distal end features. Recently introduced novel shapes such as the “Ninja Star” type while reducing the mass are difficult to manufacture, especially to deburr, because of their many interior surfaces that enable entanglement of juxtaposed baseplates. 
     The invention design, by contrast, has no interior surfaces that can entangle. The invention design allows in manufacturing operations optimization of material usage, and easy post-processing such as deburring and tumbling, and provides a low-mass base plate. Thus the invention design delivers the needed performance and makes the part manufacturable. 
     As mentioned above, the recess in the baseplate can have a U-shape or a V-shape with a variable width and length, or any shape that removes a part of the baseplate volume and yet retains the force effect of the baseplate forward edge on the load beam spring section, and supports cantilevered rigid section as needed, all without a reduction in desirable thickness in the baseplate. Preferably the recess removes as much of the baseplate as possible while keeping distributed areas for welding of the baseplate to the load beam and the aforementioned needed mechanical features. In practice the rear edge of the baseplate is also contoured to have a suitable radius for further mass reduction without affecting performance or causing difficulties in manufacturing operations. 
     The width of the legs formed by the recess and the side edges as described herein typically has a lateral width (from side edge to closest recess edge) of 0.0650 inch across) provided that width is larger than the size of the boss portion outside diameter. The boss will typically have an outside diameter of 0.0660 inch. This relationship smaller boss outside diameter and greater leg lateral width acts to prevent the intertwining of the baseplates during their tumble deburring in post-processing. As noted above, the baseplate thickness should be at least 0.004 inch, and optimally 0.006 to 0.008 inch. 
     The invention design thus addresses the post-processing of a reduced mass baseplate and delivers a solution thereto. In addition, the baseplate edges next to the spring section area are kept essentially intact despite the nonessential elimination of mass area. Weld points are preserved for attaching the base plate to the load beam. 
     With reference now to the drawings in detail in FIGS. 1-3 the invention low mass baseplate  10  attaches to suspension load beam  12  having a rigid section  14 , a spring section  16 , and a base section  18 , by welding, e.g. at points  22 , the load beam base section. The baseplate  10  comprises a typically metal planar portion  24  that is weld-attached to the load beam base section  18 , and integrally formed therewith, a typically cylindrical boss portion  26  that attaches by swaging to aperture  28  in actuator arm  32 . 
     Baseplate planar portion  24  is a flange that has a front edge  34  and a rear edge  36  and left and right lateral edges  38 ,  42  respectively therebetween. The cylindrical boss portion  26  is spaced inwardly as shown from the planar portion edges  34 ,  36 ,  38  and  42 . Boss portion  26  has a given outside diameter D that is considered when sizing the lateral width W of the legs  44 ,  46  so as to properly size the recess  48  therebetween, as hereinafter more fully explained. 
     For mass reduction, the baseplate planar portion  24  distal front edge recess  48  is preferably coaxial with the boss portion  26  and spaced distally therefrom. Recess  48  is devoid of metal so as to effect mass reduction. Recess  48  defines with the baseplate left and right edges  38 ,  42  respectively left and right legs  44 ,  46 . Legs  44 ,  46  each have a lateral extent or width W that defines the lateral extent L of the recess  48  to be greater than the outside diameter D of boss portion  26 . Since they are unable to engagingly interfit or interlock although tumbled in juxtaposition, recess  48  and boss  26  and thus their respective baseplates  10  do not become entangled with each other in tumble deburring operations. 
     In particular cases, the extent L of the low mass baseplate planar portion recess  48  along its lateral axis is less than its extent N normal to the lateral axis. Preferably, the recess  48  terminates inwardly in a radiused terminal  58 , FIG. 1; or, as shown in FIG. 4 recess  448  has a V-shape and terminates inwardly in a pointed terminal  56 . 
     In addition, to maintain the support for the spring section areas  66 ,  68  while still reducing mass, baseplate  10  has its left and right legs  44 ,  46  define left and right front edges  62 ,  64  respectively that are adjacent to and engage these left and right spring section areas, respectively, at the load beam spring section edge  116 . 
     Baseplate rear edge  36  and the left and right lateral edges  38 ,  42  are as shown radiused at their intersection to reduce mass further. Baseplate rear edge  36  preferably comprises a smooth curve  72  commencing at the center  74  of the rear edge  36  and terminating on the left and right lateral edges  38 ,  42  of the planar portion at left and right points  76 ,  78  opposed across the boss portion  26 . 
     The invention baseplate  10  is used in combination with the load beam  12  with the baseplate planar portion  24  weld-attached to the load beam base section  18  at laterally and longitudinally distributed points  22  between the most rearward part of the boss portion  26  and the planar portion front edge  34 . 
     In a typical baseplate according to the invention, the baseplate  10  has height from the center of the boss  26  to the ends of the legs  44 ,  46  of about 0.1000 inch, a width of about 0.2000 inch, a recess  48  depth of about 0.0500 inch, and a recess lateral extent of about 0.0700 inch. The corresponding boss  26  will have an outside diameter of about 0.0660 inch (with an inside diameter of about 0.0500 inch). 
     The invention thus provides for use in disk drive suspensions an improved baseplate that has reduced mass but that maintains the desired thickness for mechanical properties by contouring the common baseplate in areas not critical to performance to reduce mass without undue loss in the mechanical properties. The invention baseplate has a novel shape that accommodates all mechanical requirements, such as maintaining the base plate edge at the load beam spring section, keeping a minimum thickness or greater, and providing distributed welding sites, all while having a reduced mass. The foregoing objects are thus met.