Abstract:
A method and apparatus for making a shaped-spring assembly. The method and apparatus utilizes a spring forming apparatus which facilitates the forming of shaped springs without adversely effecting the characteristics of the spring, and a magazine arrangement which stores and loads shaped springs, while maintaining the shape of the springs. The magazine arrangement further permits the storage of a plurality of the shaped springs without fatiguing a leading edge of the spring. With the apparatus and method of the present invention, it is possible to load empty shaped spring cavities at a select location, such as at a field site, and also have a steady supply of shaped springs available for quick replacement. The forming apparatus is designed so as to easily cooperate and/or be mounted onto the magazine arrangement so as to facilitate the transfer of shape springs which are shaped by the forming apparatus into the magazine arrangement.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus and method for making a shaped-spring assembly for use in a magnetic head-to-media backer. More specifically, the present invention relates to an apparatus and method for making a shaped-spring assembly which involves the use of a shaped spring forming unit and a shaped spring storing and loading magazine.  
         BACKGROUND OF THE INVENTION  
         [0002]    Shaped-spring assemblies have been used in a number of electrical and mechanical devices such as cameras, tape decks, sound recording devices, and automated materials handling machinery. These shaped-spring assemblies are commonly called bubble-spring assemblies and are employed in situations that require a constant load with the ability to accommodate large spacial displacements. A typical bubble-spring assembly provides a restraining force against a moving piece of a magnetic section of a film, so that the film is held against a recording head under constant pressure.  
           [0003]    A bubble-spring assembly typically includes a cavity that comprises a block and the bubble spring. The cavity includes a shaped-hollow cavity formed through the block and the bubble spring is typically small and thin. Due to the size of the spring, delicate handling of the spring is required. The bubble spring is positioned within the cavity to form a convex or arched portion that extends beyond the dimension of the cavity block. In this manner, the bubble spring is placed under tension and will thereby provide a spring force against an article, such as film, that has displaced the spring into the cavity. Prior to shaping and insertion into the cavity, the bubble spring is a flat elongated piece of thin material, typically metal, and commonly referred to as a spring blank. This type of bubble spring assembly is disclosed in, for example, U.S. Pat. Nos. 5,274,522 and 5,531,008.  
           [0004]    In a conventional APS film strip, there is a magnetic layer that provides a way to read and/or write data. The above-mentioned U.S. Pat. No. 5,274,522 as noted above, discloses a bubble spring load pad which is a film backer pad used for urging the film base to a magnetic head. This backer pad (also known as a bubble spring assembly) includes a cavity and the bubble spring. After extended use of the assembly including the bubble spring, it has been found that the spring needs to be routinely replaced. This is due to the constant urging of the bubble spring against the magnetic layer of the film. Due to cost, it is not economically feasible to replace both the cavity and the bubble spring each time the spring needs to be replaced. It is preferred to use the existing cavity and install a new spring. However, as noted above, the springs tend to be small and thin, and thus very difficult to accurately replace within a small cavity without adversely effecting the spring characteristics of the spring. Also, in reloading bubble springs within a cavity, manufactures and/or consumers may use springs from manufactures that may provide poor spring performance due to inferior material and/or manufacturing methods.  
           [0005]    A method of replacing a spring as disclosed in the above-mentioned U.S. Pat. No. 5,531,008 is complex and has a fair amount of cost and usage difficulty associated with it. The apparatus as disclosed in U.S. Pat. No. 5,531,008 also only supplies one spring at a time. Further, the method of spring installation as disclosed in the U.S. Pat. No. 5,531,008 causes the leading half of the spring to be fatigued during spring installation by the way the leading edge of the spring gets forced into, then around, a tight radius. This causes the leading half of the spring to be fatigued. This may cause the spring load to be lower in head load after spring installation than is desired. That is, the film has what is called an anticlastic effect (edge curl) under the edge of the film on/or close to the magnetic head track signal location. Under certain situations such as lower humidity and/or core set film, a lower gram load could limit the springs ability to provide the needed force on the outside track location to provide a high enough force to obtain consistent read/write signal processing.  
           [0006]    The loading or replacement of springs needs to be done in a manner which does not result in too large or too low of a spring force, since a large spring force would tend to damage the film or article that the spring rides against, and a low spring force would not provide enough of a force to urge the spring against, for example, a magnetic head.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides for an improved method and apparatus for making a bubble spring (hereinafter referred to as a shaped-spring) assembly. The method and apparatus of the present invention utilizes a novel shaped-spring magazine arrangement as well as a novel spring forming unit.  
           [0008]    The present invention provides for a mechanism which reduces or eliminates the necessity of installing undesired springs from manufactures that may use unapproved springs which can cause poor performance. This is because the present invention provides for a magazine that can be pre-loaded at a controlled location.  
           [0009]    The present invention provides for a shaped spring magazine arrangement for making a shaped spring assembly. The shaped spring magazine arrangement comprises a base member having a first section adapted to hold a row of shaped springs and a second section adapted to hold a shaped spring cavity. A first shaped spring in the row of shaped springs is located at a first end of the first section adjacent to the second section, and a last shaped spring of the row of shaped springs is located at a second end of the first section opposite to the first end. The magazine arrangement further comprises a plurality of spacer members provided on the first section of the base member so as to be positioned between the shaped springs in the row of shaped springs; and a pusher member adapted to be inserted into the second end of the first section so as to push against the last shaped spring of the row of shaped springs, and cause the first shaped spring of the row of shaped springs to be inserted into a shaped spring cavity located at the second section.  
           [0010]    The present invention further relates to a method of making a shaped-spring assembly. The method comprises the steps of alternatively providing shaped springs and spacer members on a first section of a base member so as to create a row of the shaped springs with the spacer members located between the shaped springs; providing a shaped spring cavity on a second section of the base member; and pushing a first shaped spring of the row of shaped springs which is furthest from the shaped-spring cavity, so as to urge a second shaped spring from the row of shape springs which is closest to the shaped spring cavity out of the first section of the base member and into the shaped spring cavity so as to form a shaped spring assembly.  
           [0011]    The present invention further relates to a shaped spring magazine arrangement for making a shaped-spring assembly that comprises a base member having a first part adapted to hold at least one shaped spring and a second part adapted to hold a shaped spring cavity.  
           [0012]    The present invention further relates to a method of making a shaped spring assembly which comprises the steps of positioning shaped springs in a row on a first part of a base member; placing an empty shaped-spring cavity on a second part of the base member; and loading one of the shaped springs in the row of shaped springs into the empty shaped-spring cavity.  
           [0013]    The present invention further relates to a spring shaping tool for forming shaped springs. The spring shaping tool comprises a housing assembly having a longitudinal bore adapted to hold a mandrel therein, and a recess which extends in a direction transverse to the longitudinal bore; a spring former sized to be slidably insertable in said recess, the spring former comprising a slot which is sized to receive a spring blank and an opening extending from the slot. The spring former is slidable in the recess from at least a first position to a second position in which the opening surrounds the mandrel, such that a sliding of the spring former to the second position causes a spring blank positioned in the slot to be partially wrapped around the mandrel and extend into the opening, to thereby form a shaped spring.  
           [0014]    The present invention further relates to a method of shaping a spring blank to form a shaped spring which comprises the steps of placing a spring blank in a slot of a spring former which is adapted to fit within a recess of a housing assembly, with the spring former having an opening which extends from the slot; and pressing the spring former having the spring blank therein in the recess of the housing assembly. The housing assembly has a longitudinal bore with a mandrel positioned therein that extends through the recess, such that the spring blank in the slot of the spring former partially wraps around the mandrel and extends into the opening, to thereby form a shaped spring.  
           [0015]    The present invention further relates to a spring forming and loading assembly which comprises a shaping tool for shaping spring blanks to form shaped springs; and a shaped spring magazine for storing shaped springs formed by the shaping tool as a row of shaped springs, and loading the shaped springs into an empty shaped spring cavity.  
           [0016]    The present invention further relates to a method of forming, storing and loading shaped springs to form shaped spring assemblies, which comprises the steps of (a) placing a spring blank in a slot of a spring forming member, with the spring forming member having an opening which extends from the slot; (b) pressing the spring forming member having the spring blank therein within a recess of a housing assembly, with the housing assembly having a bore with a mandrel positioned therein that extends through the recess, such that the spring blank in the slot of the spring forming member partially wraps around the mandrel and extends into the opening, to thereby form a shaped spring; (c) transferring the shaped spring to a magazine; (d) positioning the shaped spring on a first part of the magazine; (e) repeating the steps (a)-(d) until a desired number of shaped springs are formed and positioned in a row on the first part of the magazine; (f) placing an empty shaped spring cavity on a second part of the magazine; and (g) pushing one end of the row of shaped springs so as to load one of the shaped springs in the row of shaped springs into the empty shaped spring cavity.  
           [0017]    Advantages of the method and apparatus of the present invention as described above is that it permits multiple shaped springs to be loaded one at a time by way of a storage method, and facilitates the storage of a multitude of springs for installation purposes.  
           [0018]    Further, the method and apparatus of the present invention permits the loading of a magazine to be controlled at a select location. As an option, the magazine that is preloaded with shaped springs can be supplied to a field site for easy, correct spring installation capabilities. This allows the customer (end user) to have a steady supply of shaped springs available for quick replacement options, and permits the supply of shaped springs to be under a controlled environment by separating a spring forming function from spring storing and loading functions.  
           [0019]    Further, a higher average installation load is realized by not fatiguing the leading edge of the spring installation.  
           [0020]    Also, the present invention provides for a low cost and easy option for replacing springs since an end user could maintain a supply of magazines which are pre-loaded with shaped springs at a factory on site.  
           [0021]    The method and apparatus of the present invention also facilitates field repairs by eliminating the need to send a cavity back to a manufacturer for repair. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is an isolated perspective view of a shaped-spring assembly made in accordance with the present invention;  
         [0023]    [0023]FIG. 2 is a perspective view of a shaped spring forming and loading apparatus and a shaped spring magazine arrangement in accordance with the present invention;  
         [0024]    [0024]FIG. 3( a ) is a perspective view of a shaped-spring magazine arrangement for making a shaped-spring assembly as shown in FIG. 1; and  
         [0025]    [0025]FIG. 3( b ) is a top view of the shaped spring magazine arrangement illustrated in FIG. 3( a ). 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    Referring now to the drawings, wherein like reference numerals represent identical or corresponding parts through the several views, FIG. 1 illustrates a shaped-spring assembly  5  that is made in accordance with the apparatus and method of the present invention. As illustrated in FIG. 1, shaped-spring assembly  5  includes a shaped-spring cavity  7  which generally comprises end sections  9   a,    9   b  and a middle flat head section  11 . The combination of end section  9   a  and one side of flat head section  11  defines a receiving section  15   a , while end section  9   b  and the opposite side of flat head section  11  defines a further receiving section  15   b.  Shaped spring assembly  5  further includes a spring blank which is curved to form a shaped spring  17 . More specifically, shaped spring  17  is curved or arched so that the arched ends are held within receiving sections  15   a ,  15   b  such that spring  17  exhibits spring-like characteristics. Thus, spring  17  is placed under tension within shaped-spring cavity  7 , so as to provide a spring force against an article, such as the magnetic layer of photosensitive film within a camera.  
         [0027]    It is noted that the spring blank which forms shaped spring  17  is a delicate and fragile item. A typical spring blank has a thickness of approximately 0.0015 inches (0.0381 mm), a length of less than an inch (2.54 cm), and a width not exceeding 0.125 inches (0.317 cm). The spring blank is further commonly formed from stainless steel. In many applications, the spring blank includes a highly burnished surface that will contact super sensitive material. In an environment in which the shaped spring  17  is to contact, for example, a magnetic layer on film, it is desirable that the shaped spring not only have a predictable stress strain history resulting from the shaping process, but also retain the qualities associated with the burnished surface by avoiding even minor or hair line scratches. Thus, a precise and controlled method and apparatus are necessary so as to properly load a spring blank into shaped-spring cavity  7  to form shaped spring  17  and thereby form shaped spring assembly  5 .  
         [0028]    [0028]FIG. 2 illustrates an overall system  20  for shaping, storing and loading spring blanks  26  into an empty shaped-spring cavity  7 . As shown in FIG. 2, system  20  includes a shaping tool or spring forming and loading apparatus  22 , and a shaped-spring magazine arrangement  24 . For loading spring blanks into shaped-spring magazine arrangement  24 , spring forming and loading apparatus  22  can be connected or mounted to shaped spring magazine arrangement  24  by way of, for example, locating pins  28  which cooperate with corresponding recesses  29  on shaped-spring magazine arrangement  24  or vice versa. It is recognized that this is just one method of connecting or mounting forming and loading apparatus  22  onto magazine arrangement  24 , and other methods such as screws, pins etc., can be utilized to mount forming and loading apparatus  22  onto magazine arrangement  24 .  
         [0029]    With respect to the process and apparatus for shaping spring blanks  26  in forming and loading apparatus  22 , apparatus  22  includes a housing  30  and a shaper  32  adjacently positioned next to each other as two units or an integral unit to form a housing assembly. Spring forming and loading apparatus  22  further includes a mandrel  34  that extends through housing  30  and shaper  32 , as well as a spring conveyer or rod-like pusher member  36 . Housing  30  further includes the aforementioned locating pins  28 .  
         [0030]    During use of forming and loading apparatus  22  for forming shaped springs  17  which are initially in the form of spring blanks  26 , spring blanks  26  are first placed in a recess  40  in shaper  32 . Shaper  32  further includes a spring former  42  slidably insertable in the recess  40 , or in a further recess downstream (i.e., closer to housing  30 ) of recess  40 . Spring former  42  includes a slot  44  which is opened in a first direction and extends to a substantially circular portion  46  in a second direction. Substantially circular portion  46  generally matches the curvature of mandrel  34 . Therefore, with system  20  of the present invention, a user would place spring former  42  in recess  40 , and place a spring blank  26  into recess  40  or a recess upstream of recess  40  so that spring blank  26  is aligned with slot  44  of spring former  42 . Thereafter, spring blank  26  can be slid or pushed into slot  44  by way of conveyor  36 . As a further option, spring blank  26  can be first placed in slot  44  of spring former  42 , with spring former  42  then being inserted in recess  40 . Thereafter, spring former  42  having spring blank  26  positioned in slot  44  is further inserted or pressed in recess  40  so that spring blank  26  is bent around mandrel  34  as opening  46  extends around mandrel  34 . This effectively forms shaped spring  17  around mandrel  34 . Thereafter, shaped spring  17  is moved along mandrel  34  by use of conveyer  36  until shaped spring  17  exits through an opening  50  in housing  30 , and enters a slot or opening  52  in magazine arrangement  24  (see FIG. 1). Spring conveyer  36  can then be moved rearwardly, and a bubble spring spacer  54  as illustrated in FIG. 3( a ) or  3 ( b ) is also placed in slot  52  of magazine arrangement  24 . Thereafter, shaped spring  17  as well as spacer  54  are pushed along slot  52  by way of rod-like pusher member  56  of magazine arrangement  24 , and the process is again repeated for the next shaped spring and spacer member.  
         [0031]    Now, the details of magazine arrangement  24  will be described. As illustrated in FIGS.  3 ( a ) and  3 ( b ), magazine arrangement  24  includes a base  60  which has a first part or section  60   a  that includes slot  52  and a second part or section  60   b  that includes mounting pins  62 . Mounting pins  62  are effective to locate bubble spring cavity  7 . That is, mounting pins  62  can cooperate with recesses  64  (see FIG. 1) of cavity  7 . Therefore, base member  60  of magazine arrangement  24  essentially includes first part or section  60   a  which is designed to receive, hold and store shaped springs  17  as well as spacer members  54 , and second part or section  60   b  which includes the mounting pins  62  and is designed to hold a shaped spring cavity  7 . First part or section  60   a  of base member  60  also includes slot  52  as described above, into which shaped springs  17  are inserted from forming and loading apparatus  22 . Slot  52  is generally sized so as to tightly receive shaped springs  17  and maintain the shape of shaped springs  17 as shaped springs  17  are slid along slot  52  and loaded into cavity  7 . FIGS.  3 ( a ) and  3 ( b ) illustrate magazine arrangement  24  being filled with shaped springs  17 , with intervening spacer members  54  between each of the shaped springs  17  so as to facilitate the sliding of shape springs  17  along slot  52  by use of pusher member  56 . As further illustrated in FIGS.  3 ( a ) and  3 ( b ), in loading shaped springs  17  and spacer members  54  into slot  52  of magazine  24 , a row of shaped springs  17  with intervening spacer members  54  is formed.  
         [0032]    As an option, magazine  24  can include a top cover  70  having an opening which permits one to visually observe the amount of shaped springs  17  in first section  60   a  of magazine  24 .  
         [0033]    With a magazine arrangement  24  as illustrated in FIGS.  3 ( a ) and  3 ( b ), in order to load an empty shaped-spring cavity  7  mounted on second section  60   b,  pusher member  56  is operated to push against one end of the row of shaped springs  17 , i.e., a user will push pusher member  56  against a last spacer member  54 L or shaped spring  17 L in the row of shaped springs  17 , so as to urge a first shaped spring  17 F in the row into the empty shaped spring cavity  7 . Thus, shaped spring  17 F is loaded into cavity  7  while maintaining the shape of shaped spring  17 F, since spring  17 F will travel along slot  52  as it enters cavity  7 . After spring  17 F is loaded into cavity  7 , shaped-spring assembly  5  as illustrated in FIG. 1 is formed. A user will thereafter remove shaped-spring assembly  5  from section  60   b  and continue to push pusher member  56  against the last shaped spring or spacer member ( 17 L or  54 L) to discard the spacer member  54  which follows the loaded shaped spring  17 F in the row of shaped springs. This spacer member  54  can thereafter be discarded or stored for future use. A user can then place a second empty cavity  7  onto section  60   b  and load a further shaped spring  17  from the row of shaped springs into the second cavity  7  by utilizing pusher member  56  in the manner described above. The user can continue to load shaped springs  17  into empty shaped-spring cavities  7  until the desired amount of shaped-spring assemblies  5  are formed. Additionally, once magazine arrangement  24  is empty, a user can form and load additional shaped springs into slot  52  utilizing forming and loading apparatus  22  as described above and shown in FIG. 2.  
         [0034]    Although the present invention illustrates manually pushing the shaped springs by using pusher member  56 , the present invention is not limited thereto. It is recognized that the present invention can be automated by providing for an automatic plunger type system which can be controlled to push one shaped spring into a corresponding empty shaped-spring cavity. Also, other types of devices for pushing, sliding, pulling or moving an article, such as the shaped spring, along a slot can be utilized.  
         [0035]    Thus, the present invention provides for a forming and loading system which facilitates the shaping of springs and further facilitates the storage and loading of springs into an empty shaped-spring cavity.  
         [0036]    The present invention further provides for an improved forming and loading apparatus which facilitates the conversion of spring blanks into shaped springs, and can be easily mounted or interconnected to a storage magazine arrangement.  
         [0037]    The present invention further provides for an improved storage magazine arrangement which has the capability of storing a plurality of shaped springs, and permits the easy loading of shaped springs into an empty shaped spring cavity.  
         [0038]    With the apparatus and method of the present invention, it is possible to load empty shaped spring cavities at a controlled location, and it is also possible to convert spring blanks into shaped springs, while maintaining a predictable stress strain history resulting from the shaping process. Further, it is possible to store the shaped springs in a magazine arrangement while maintaining their shape.  
         [0039]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.