Abstract:
A tape measure device has an elongated blade with a central concave-convex segment with at least one planar segment adjoining edgewise the central concave-convex segment to form a junction that extends substantially along the entire length of the elongated blade. During formation of the blade the junction is annealed to avoid formation of a flaw or incipient fracture along the junction.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a continuation of application Ser. No. 11/430,340 now U.S. Pat. No. 7,174,654, filed May 9, 2006; which is divisional of application Ser. No. 10/945,679, filed Sep. 21, 2004, now U.S. Pat. No. 7,096,596, issued Aug. 29, 2006. These related applications are incorporated herein by reference and made a part of this application. Moreover, the inventors incorporate herein by reference any and all U.S. patents, U.S. patent applications, and other documents, hard copy or electronic, cited or referred to in this application. 

   DEFINITIONS  
   The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. 
   “Rectangular shape” includes square shape. 
   BACKGROUND OF THE INVENTION 
   A tape measure is a device used to measure such things as length distance. A tape measure typically comprises an elongated blade that is wound about a reel and stored within a housing. A user employs the tape measure by unwinding the elongated blade, extending the blade through an opening in the housing. The elongated blade has rule  1  markings to measure length and distance. 
   Examples of tape measures are disclosed in U.S. Pat. Nos. 1 6,324,769; 6,367,161; and 6,662,463. As disclosed in these patents, it is desirable that an extended portion of the elongated blade be as linear as possible. For example, the extended blade portion may have a standout arcuate length of at least ten feet with a horizontal linear length greater than ninety-seven percent of the standout arcuate length. As this extended portion increases in length, its tendency to bend downward also increases due to the increase in the weight of the extended portion. This bending tendency is obviated at least to some degree by controlling the dimensions of the blade and the materials used in its construction. Additionally, the blade&#39;s cross-sectional shape is configured to resist bending. For example, the blade&#39;s cross-sectional shape may include a concave-convex central section adjoining one or more planar segments. Although this cross-sectional shape resists bending, it presents a problem; namely, along any junction line where a planar segment merges with the concave-convex central section, a flaw or incipient fracture is created using conventional stamping a techniques in manufacturing the elongated blade. 
   SUMMARY OF THE INVENTION 
   This invention has one or more features as discussed subsequently herein. After reading the following section entitled “DETAILED DESCRIPTION OF ONE EMBODIMENT OF THIS INVENTION,” one will understand how the features of this invention provide its benefits. The benefits of this invention include, but are not limited to, providing a tape measure blade having a cross-sectional configuration that resists bending but avoids during manufacture the formation of flaws or incipient fractures. 
   Without limiting the scope of this invention as expressed by the claims that follow, some, but not necessarily all, of its features are: 
   One, the tape measure device of this invention includes an elongated blade that, when in an extended position, has a predetermined cross-sectional curvature formed by a concave-convex segment and at least one planar segment adjoining edgewise the concave-convex segment. At the adjoining edges of these segments a junction is formed that extends substantially along the entire length of the elongated blade. This junction is annealed during formation of the blade to avoid creating a flaw or incipient fracture along the junction. 
   Two, annealing may comprise passing a substantially flat strip of metallic material lengthwise through a slit opening in a die and heating the strip. The flat strip of metallic material is heated to a temperature substantially above ambient temperature but below the melting point of the metallic material. The die or the material may be heated, or both may be heated, or the flat strip of metallic material may be heated prior to passing it through the slit opening. The metallic material may be selected from the group consisting of chromium, nickel, carbon, and iron. A strip made from these materials is flexible and resilient material. In the case of steel strip material, the strip passes through the die at a rate from about 100 to about 200 linear feet per minute and is heated to a temperature from about 500 to about 700 degrees Fahrenheit. 
   Three, the slit opening has a configuration substantially conforming to the predetermined cross-sectional curvature of the blade. In one embodiment, the predetermined cross-sectional curvature of the extended blade portion has predetermined dimensions and the slit opening has dimensions that are slightly less than the predetermined dimensions of the cross-sectional curvature of the extended blade portion. Upon passing such a smaller dimensioned metallic strip through the slit in the die, the ductile metallic material is worked, i.e., stretched. 
   Four, the flat strip of metallic material may have a minimum of thickness of at least about 0.0030 inch, for example, from about 0.0045 to about 0.0060 inch, and a width from about 0.500 to about 1.625 inches. In one embodiment, the predetermined cross-sectional curvature comprises a central concave-convex segment straddled by a pair of planar segments. The central concave-convex segment may have a radius of curvature from about 0.5 to about 1.0 inch, and the planar segments each may have a width from about 0.25 to about 0.75 inch. The planar segments may be substantially equal in width. 
   These features are not listed in any rank order nor is this list intended to be exhaustive. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of this invention, illustrating all its features, will now be discussed in detail. This embodiment depicts the novel and non-obvious tape measure device of this invention as shown in the accompanying drawing, which is for illustrative purposes only. This drawing includes the following Figures (Figs.), with like numerals indicating like parts: 
       FIG. 1  is a perspective view of the tape measure device according to one embodiment of this invention. 
       FIG. 2  is a side view of the tape measure device shown in  FIG. 1  with portions broken away and the blade completely retracted. 
       FIG. 2A  is a side view similar to that of  FIG. 2  with portions broken away and the blade partially unwound and a portion thereof in an extended position. 
       FIG. 3  is a cross-sectional view of the elongated blade taken along line  3 - 3  in  FIG. 2A . 
       FIG. 3A  is a partial, cross-sectional view of the elongated blade taken along line  3 A- 3 A in  FIG. 3 . 
       FIG. 3B  is a partial, cross-sectional view of the elongated blade taken along line  3 B- 3 B n  FIG. 3 . 
       FIG. 3C  is a plan view taken along line  3 C- 3 C in  FIG. 3 . 
       FIG. 3D  is a plan view taken along line  3 D- 3 D in  FIG. 3 . 
       FIG. 4  is a perspective view illustrating a flat strip of metal passing through a die to form the blade according to this invention. 
       FIG. 5  is a plan view of the blade illustrating the ruled markings on the surface of the blade used in the tape measure device shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIGS. 1 through 3 , the tape measure device  10  of the present invention includes an elongated blade  20  heat-treated and worked in accordance with this invention. This blade  20  is stored in a wound-up condition in a blade holding assembly  14  mounted to a housing  12 . As shown in  FIG. 5 , the elongated blade  20  has on at least one surface graduated markings  50 , for example ruled lines denoting inches and fractions thereof, located on a top side  20   d , thus allowing a user to measure length or distance. Ruled lines denoting metric lengths or distance may also be used. The housing  12  is a box-like structure having a substantially rectangular shape when view from the side as shown in  FIG. 2 . Within the housing  12  is an internal chamber  12   c  that receives a reel  18 , a component of the blade holding assembly  14 . The blade  20  has an internal end  20   c  connected to the reel  18  and a free end  20   b  extending outwardly through an opening  12   a  in the housing  12 . 
   As shown in  FIG. 2A , the blade holding assembly  14  is of conventional design, being manually actuated to hold a selected portion  60  ( FIG. 2A ) of the blade  20  in an extended position and manually actuated to release the extended blade  20 , rewinding the blade portion  60  about the reel  18 . The blade  20  is unwound manually to extend outwardly from the opening  12   a  in the housing  12  any selected portion  60  of the blade  20  as determined by the user. The blade holding assembly  14  includes the reel  18  about which the blade  20  is normally completely wound about as shown in  FIG. 2  and a button  14   a  on the exterior of the housing  12  for operating a brake  12   b  located within the housing  12 . In one position of the button  14   a  as shown in  FIG. 2 , the brake  12   b  is disengaged. In another position shown in  FIG. 2A , the brake  12   b  is engaged to hold the selected extended portion  60  in place. The blade  20  may be withdrawn from the housing  12  when the brake  12   b  is engaged, so the blade is held in any desired extended position. Release of the brake  12   b  initiates the rewinding of the extended blade portion  60 . 
   The reel  18  is mounted within the internal chamber  12   c  for rotation. It includes a cylinder  18   c , a coil spring  18   a  operatively disposed within the cylinder  18   c , and a central shaft  18   b  connected to the housing  12  about which the reel rotates. The coil spring  18   a  has one end  18   d  attached to the central rod  18   b  and its other end  18   e  attached to the cylinder  18   c . The coiled spring  18   a  is tightened as the blade  20  is manually pulled from the housing  12  so that it may rewind the extended portion  60  of the blade  20  onto the reel  18  upon manipulation of the button  14   a  to release the brake  12   b . The blade  20  is attached at its one end  20   c  to the cylinder  18   c . As the blade  20  is pulled from the housing  12 , it extends tangentially to the cylinder  18   c.    
   The brake  12   b  is located within the housing  12  and with the button  14   a  in the position shown in  FIG. 2A , the brake is engaged to push against a wound-up portion  20   a  of the elongated blade  20  to inhibit the reel  18  from rotating but not so strong as to prevent a user from further unwinding the blade from the reel  18 . As the blade  20  is extended, the brake  12   b  as shown in  FIG. 2A  continuously presses against the wound-up portion  20   a , holding the blade in any desired extended position ( FIG. 2A ) until the user pushes the button  14   a , sliding the button upward as viewed in  FIG. 2A  along the exterior of the housing  12 , moving the button to its disengaged position shown in  FIG. 2 . Pushing the button  14   a  upward, lifts the brake  12   b  from the wound up portion  20   a . Due to the action of the spring  18   a , the reel rotates counter-clockwise as viewed in  FIG. 2A , rewinding the blade  20  around the reel  18  to flatten the blade as it is wound about the reel. The blade holding assembly  14  thus enables the user to control the operation of the reel  18  so the blade remains in the selected extended position until the button  14   a  is actuated. 
   The extended portion  60  of the blade  20  has a curved cross-section as shown in  FIG. 3 . The blade  20  is substantially flat when wound about the reel  18  and its topside  20   d  faces the reel and its bottom side  20   e  faces away from the reel. The blade  20  in the wound up and flattened condition may have a width of at least about 1 inch, for example, from about 1.600 to about 1.625 inches. The blade&#39;s thickness may be about 0.0045 inches, for example, from about 0.0030 to about 0.0060 inches. The extended portion  60  of the blade  20  has a cross-sectional curvature C that is substantially uniform along the entire length  1  of the extended portion  60 . This cross-sectional curvature C comprises an arcuate, concave-convex central section  40  and a pair of lateral, substantially flat planar end segments  42 ,  44  that straddle the concave-convex central section. The adjoining edges of the planar end segments  42 ,  44  and central section  40  merge at the junction line J 1  and J 2  extending along the length of the blade  20 . The arcuate, concave-convex central section  40  may have a radius of curvature r 1  from about 0.5 inch to about 1.0 inch, a height h 2  from about 0.100 inch to about 0.250 inch, a width w 1  from about 0.600 2 inch to about 0.925 inch, and spans an angle a 1  from about 71.0 degrees to about 105.0 degrees. The extended, elongated blade  60  has a blade height h 1  from about 0.125 inch to about 0.500 inch, and a width w 2  from about 0.925 inch to about 1.25 inch. Each of the planar end segments  42 ,  44  has a width w 3  and w 4 , respectively, that are equal, for example from about 0.250 inch to about 0.750 inch. 
   The extended portion  60  of the elongated blade  20  may have a standout arcuate length of at least ten feet with a horizontal linear length greater than ninety-seven percent of the standout arcuate length. When wound-up around the reel  18 , the blade  20  is flattened. Upon moving from the selected extended position ( FIG. 2A ) to the wound-up position ( FIG. 2 ), the lateral planar segment  42  moves in a counter-clockwise direction as viewed in  FIG. 3 , and the lateral planar segment  44  moves in a clockwise direction as viewed in  FIG. 3 . 
   In accordance with one feature of this invention, an annealing process is employed to form the blade  20 . Referring to  FIG. 4 , the elongated blade  20  is formed from a flat strip of metallic material  30  that is heat-treated and worked according to this invention. The flat strip metallic material  30  may be selected from the group consisting of chromium, nickel carbon, and iron. The flat strip of metallic material  30  is heated and passed through a die  36  with a slit  34  having a shape and dimensions that are substantially identical to those of the cross-sectional curvature C of the blade  20 . Specifically, the slit  34  has a concave-convex pattern  70  straddled by a pair of lateral planar end segments  72 ,  74  to produce a curved metal strip  32 . The temperature is sufficient to heat the flat strip of metallic material  30  above ambient temperature but below its melting point, for example, a steel strip is heated to a temperature from about 500 to about 700 degrees Fahrenheit. The die may also be heated. Such a flat strip of the steel material  30  may pass through the slit  34  in the die  36  at a rate from about 100 to about 200 linear feet per minute. The slit  34  may have dimensions that are slightly less that the cross-sectional dimensions of the cross-sectional curvature C of the blade  20  to work the strip of metallic material  30 , pulling the ductile metallic material slightly as it passing through the slit  34 . The curved steel strip  32  as it emerges from the die  36  is cooled to ambient temperature to complete the annealing process. 
   SCOPE OF THE INVENTION 
   The above presents a description of the best mode contemplated of carrying out the present invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use this invention. This invention is, however, susceptible to modifications and alternate constructions from that discussed above which are fully equivalent. Consequently, it is not the intention to limit this invention to the particular embodiment disclosed. On the contrary, the intention is to cover all modifications and alternate constructions coming within the spirit and scope of the invention as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of the invention: