Patent Publication Number: US-2023160674-A1

Title: Tape Measure with Tear Resistant Tape Blade Edge

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 17/730,890, filed Apr. 27, 2022, which is a continuation of U.S. application Ser. No. 16/991,340, now U.S. Pat. No. 11,340,054, filed Aug. 12, 2020, which is a continuation of International Application No. PCT/US2019/017681, filed Feb. 12, 2019, which claims the benefit of and priority to U.S. Provisional Application No. 62/629,924, filed on Feb. 13, 2018, which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of tools. The present invention relates specifically to a tape measure, measuring tape, retractable rule, etc., that includes a tape measure blade with an edge design that increases strength and/or resists tearing. 
     Tape measures are measurement tools used for a variety of measurement applications, including in the building and construction trades. Some tape measures include a graduated, marked blade wound on a reel and also include a retraction system for automatically retracting the blade onto the reel. In some such tape measure designs, the retraction system is driven by a coil or spiral spring that is tensioned, storing energy as the tape is extended, and that releases energy to spin the reel, winding the blade back onto the reel such that automatic or non-manual tape retraction is provided. In some other tape measure designs, retraction of the tape is controlled via a manual crank, and such tape measure blades tend to have a long length. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention relates to a tape measure including a tape blade having edges designed or configured to increase durability and/or decrease tearing. In a specific embodiment, the tape blade has an upper concave surface, a lower convex surface, a first lateral edge surface extending between the left ends of the upper concave surface and the lower convex surface, and a second lateral edge surface extending between the right ends of the upper concave surface and the lower convex surface. The first and second lateral edge surfaces are designed to improve durability and/or reduce tearing. In one embodiment, the first and second lateral edge surfaces are outwardly extending convex curved surfaces, and specifically are continuous, convex curved surfaces extending between the upper and lower surfaces. In various embodiments, the first and second lateral edge surfaces are polished or otherwise finished to reduce the number and/or size of surface defects. 
     Another embodiment of the invention relates to a tape measure. The tape measure includes a housing, a reel rotatably mounted within the housing and an elongate blade wound around the reel. The elongate blade includes an elongate metal core having an upper surface, a lower surface, a first lateral edge surface extending between the upper and lower surfaces of the elongate metal core and a second lateral edge surface opposite the first lateral edge surface and extending between the upper and lower surfaces of the elongate metal core. The elongate blade includes a polymer coating coupled to the elongate metal core. The upper surface of the elongate metal core includes a concave curved section. The lower surface of the elongate metal core includes a convex curved section. The first lateral edge surface includes a convex curved section. The second lateral edge surface includes a convex curved section. The tape measure includes a retraction mechanism coupled to the reel configured to drive rewinding of the elongate blade on to the reel and a hook assembly coupled to an outer end of the elongate blade. 
     Another embodiment of the invention relates to a tape measure. The tape measure includes a housing, a reel rotatably mounted within the housing and an elongate tape measure blade wound around the reel. The elongate tape measure blade including an upper surface, a lower surface, a first metal lateral edge surface extending between the upper and lower surfaces of the elongate tape measure blade and a second metal lateral edge surface opposite the first metal lateral edge surface and extending between the upper and lower surfaces of the elongate tape measure blade. The first metal lateral edge surface includes a shaped, non-planar surface section. The second metal lateral edge surface includes a shaped, non-planar surface section. The tape measure includes a retraction mechanism coupled to the reel configured to drive rewinding of the elongate tape measure blade on to the reel. 
     Another embodiment of the invention relates to a tape measure. The tape measure includes a housing, a reel rotatably mounted within the housing and an elongate tape measure blade wound around the reel comprising an elongate metal core. The elongate metal core includes an upper surface, a lower surface, a first lateral edge surface extending between the upper and lower surfaces of the elongate metal core and a second lateral edge surface opposite the first lateral edge surface and extending between the upper and lower surfaces of the elongate metal core. The first lateral edge surface includes a polished section such that an average number of surface defects per mm 2  within the polished section is less than an average number of surface defects per mm 2  of the upper surface of the elongate metal core. The second lateral edge surface includes a polished section such that an average number of surface defects per mm 2  within the polished section is less than an average number of surface defects per mm 2  of the upper surface of the elongate metal core. The tape measure includes a retraction mechanism coupled to the reel configured to drive rewinding of the elongate tape measure blade on to the reel. 
     Additional features and advantages will be set forth in the detailed description which follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary. 
     The accompanying drawings are included to provide further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the description, serve to explain principles and operation of the various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a left side perspective view of a tape measure, according to an exemplary embodiment. 
         FIG.  2    is a left side perspective view of the tape measure of  FIG.  1    with a portion of the tape measure housing removed, according to an exemplary embodiment. 
         FIG.  3    is a cross-sectional view of a polymer coated tape blade of the tape measure of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  4    is a cross-sectional micrograph image of the inner metal layer of a tape blade showing a tear resistant edge design, according to an exemplary embodiment. 
         FIG.  5    shows various tape blade edge shapes that may be used in a tear resistant tape blade, according to various exemplary embodiments. 
         FIG.  6    shows micrograph images of a tape blade edge surface having a tear resistant edge design, according to an exemplary embodiment. 
         FIG.  7    is a cross-sectional micrograph image of the inner metal layer of a tape blade showing a conventional edge design. 
         FIG.  8    shows micrograph images of a tape blade edge surface having a tear resistant edge design. 
     
    
    
     DETAILED DESCRIPTION 
     Referring generally to the figures, various embodiments of a tape measure are shown. Various embodiments of the tape measure discussed herein include an innovative tape blade edge design that Applicant believes improves tape blade strength, durability and/or tear resistance. As will be generally understood, one of the common modes of tape blade breakage is tearing during tape retraction. In general, when the tape blade retracts, the tape blade can whip back toward the user, cinching the blade repeatedly at a single location. 
     In general, Applicant hypothesizes that the square/flat edges (see  FIG.  7   ) of typical blades have imperfections (see  FIG.  8   ) that facilitate tearing of the blade during retracting. Applicant hypothesizes that the tear initiates at the imperfection(s) during retraction and continues on into the center portion of the blade. For example, when the blade whips back and cinches at a point along the tape blade, an imperfection at that point on the blade causes stress concentration that causes initiation of blade tear. Accordingly, as discussed in detail below, Applicant has developed a variety of tape blade edge surface designs and/or surface finishes that Applicant believes will decrease tear initiation during whip, and thereby will improve tape blade strength, durability and/or tear resistance. Applicant believes that due to the technical difficulty and cost associated with profiling/finishing the lateral edges of the tape blade material, the edge designs discussed herein are counterintuitive and contrary to conventional understanding in the field of tape measure design. 
     Referring to  FIG.  1    and  FIG.  2   , a length measurement device, such as tape measure  10 , is shown according to an exemplary embodiment. Tape measure  10  includes an elongate blade, shown as coilable tape blade  14 , and a housing  18 . In general, tape blade  14  is an elongate strip of material including a plurality of graduated measurement markings, and in specific embodiments, tape blade  14  is an elongate strip of metal material (e.g., steel material) that includes an outermost end coupled to a hook assembly, shown as hook assembly  26 . As shown in  FIG.  3   , tape blade  14  may include one or more polymer layers (e.g., polymer coating layers) to help protect tape blade  14  from cracking during whip or pinch. 
     As shown in  FIG.  1   , a variable-length extended segment  22  of the tape blade  14  is retractable and extendable from the housing  18 . A hook assembly  26  is fixedly coupled to an outer end portion  30  of tape blade  14 . As will be discussed in more detail below, in various embodiments, tape blade  14  includes an edge surface and/or surface finish that improves tape blade durability. 
     As shown in  FIG.  2   , the non-extended portion of tape blade  14  is wound onto a reel  34 , which is surrounded by housing  18 . Reel  34  is rotatably disposed about an axis  38  of tape measure  10 , and a retraction mechanism  42  is coupled to reel  34  and configured to drive reel  34  about rotation axis  38  which in turn provides powered retraction of tape blade  14 . Retraction mechanism  42  may include one or more elongated spiral springs that provides the retraction energy to retraction mechanism  42 . In other embodiments, the retraction mechanism includes an electronic motor. A tape lock  46  is provided to selectively engage tape blade  14 , which acts to restrain retraction mechanism  42  such that extended segment  22  of tape blade  14  remains at a desired length. 
     Referring to  FIG.  1   , housing  18  includes a first side wall  50 , a second side wall  54 , and a peripheral wall  58  connecting first side wall  50  and second side wall  54 . First side wall  50 , second side wall  54 , and peripheral wall  58  define an internal cavity  62 , shown in  FIG.  2   , in which reel  34  and retraction mechanism  42  are housed. Referring to  FIG.  1   , first side wall  50  and second side wall  54  has a substantially circular profile  66 . In other embodiments, the side walls may be rectangular, polygonal, or any other desired shape. Portions of the housing  18  may be co-molded or separately formed of a resilient material, such as a natural or synthetic rubber. In the illustrated construction, housing  18  is formed with housing bumpers  70  and a support leg  74  which extends from a lower portion  78  of the peripheral wall  58 . 
     A slot  82  is defined along a forward portion  86  of peripheral wall  58 . Slot  82  provides an opening in the tape measure housing which allows tape lock  46  to extend into housing  18 . In addition, slot  82  provides a length sufficient to allow tape lock  46  to be moved relative to housing  18  between locked and unlocked positions. 
     Below the slot  82 , a tape port  90  is provided in peripheral wall  58 . Tape port  90  has an arcuate shape  94 , corresponding to an arcuate cross-sectional profile of tape blade  14 . The tape port  90  defines an opening into the housing that allows for the retraction and extension of tape blade  14  to and from the internal cavity  62  defined within housing  18 . 
     As shown in  FIGS.  1  and  2   , tape measure  10  includes a finger guard assembly  98 . Finger guard assembly  98  includes a guard  102  and a guard support member  106 . As shown in  FIG.  1   , the portions of guard  102  external to housing  18  are substantially U-shaped and extend downward from housing  18 . As shown in  FIG.  2   , when tape blade  14  is in the retracted position, a rear surface of hook assembly  26  abuts guard  102 . 
     Referring to  FIG.  3   , a cross-sectional view of tape blade  14  is shown. Tape blade  14  includes an elongate core or inner layer  110  formed from a thin, elongate strip of metal material. In a specific embodiment, inner layer  110  is formed from a strip of steel material. In a specific embodiment, inner layer  110  has a thickness, T 1 , of less than 0.13 mm (with up to a 25% thickness variation), specifically 0.9 mm to less than 0.13 mm (with up to a 25% thickness variation), and more specifically of 0.9 mm to 0.12 mm (with up to a 25% thickness variation). Inner layer  110  may be formed in a concavo-convex configuration (as shown in  FIG.  3   ). Inner layer  110  may be an alloyed spring steel, alloyed high strength steel, etc. In one embodiment, the steel is of a hardness between 50-54 RHC. In another embodiment, the steel is of a hardness between 45-60 RHC. 
     In various embodiments, inner metal layer  110  includes an upper surface that includes at least one concave section and a lower surface that includes at least one convex section. In specific embodiments, the concave and convex sections extend the entire length of the tape blade. In various embodiments, tape blade  14  includes an upper coating layer  112  coupled to (e.g., attached, bonded, glued, etc.) the concave upper surface of inner metal layer  110  and a lower coating layer  114  coupled to (e.g., attached, bonded, glued, etc.) the convex lower surface of inner metal layer  110 . In general, coating layers  112  and  114  are formed from a polymer material, and in a specific embodiment, are formed from a nylon material. In specific embodiments, coating layers  112  and  114  are formed from a material that has a modulus of elasticity less than the modulus of elasticity of the metal material of inner layer  110 . In specific embodiments, coating layers  112  and  114  are formed from a material that has a hardness less than the hardness of the metal material of inner layer  110 . In specific embodiments, the coating layers discussed herein are formed from a nylon  12  material and/or a nylon  6 / 6  material. 
     As shown in  FIG.  3   , coating layer  112  has a thickness, T 2 , and coating layer  114  has a thickness, T 3 . In specific embodiments, the total thickness of the tape blade coating (i.e., the combined thickness of layers  112  and  114 , T 2 +T 3 ) is greater than or less than T 1 . 
     In specific embodiments, the total tape blade thickness (inclusive of all of the coating and the core layer, i.e., T 1 +T 2 +T 3 ) is between 0.15 mm and 0.5 mm. In various embodiments, T 1 +T 2 +T 3  is between 0.15 mm and 0.2 mm, and specifically is 0.18 mm. In various embodiments, T 1 +T 2 +T 3  is between 0.3 mm and 0.4 mm, and specifically is 0.36 mm. 
     In one embodiment, coating layers  112  and  114  may be applied over the entire length of inner layer  110 . In one embodiment, coating layers  112  and  114  are applied over at least 6 feet of the length of inner layer  110 , specifically over at least 8 feet of the length of inner layer  110 , and more specifically over at least 10 feet of the length of inner layer  110 . In specific embodiments, these coating lengths are contiguous coating lengths. This may provide increased tear resistance in areas of the tape blade  14  prone to increased wear, while maintaining compactness of the tape relative to a tape blade that has the coating over the entire length. In one embodiment, coating layers  112  and  114  begin at the end of the tape blade  14  proximate the hook. In another embodiment, the coating starts at a location of the blade spaced apart from the end proximate hook assembly  26 . 
     In some embodiments, coating layers  112  and/or  114  do not have uniform thicknesses along the width and/or length of tape blade  14 . In some such embodiments, coating layers  112  and/or  114  may be applied in a pattern (e.g., a honeycomb pattern, a checkered pattern, etc.) where there are portions of thicker and thinner coating distribution across both the length and width of the tape blade  14 . In such embodiments, T 2  and T 3  shown in  FIG.  3    represent the thickness measured through the thickest portion of the coating pattern. In some such embodiments, the ranges of T 2  and T 3  discussed herein represent the maximum thickness of coating layers  112  and  114  at any portion along the length of tape blade  14 . In some such embodiments, the combined maximum coating and blade thickness may be 0.4 mm, but in other areas along the length and width of the tape blade, the coating and blade thickness will be less (e.g., as measured at the thinner coating portions of the coating pattern). In other embodiments, the ranges of T 2  and T 3  discussed herein represent the average thickness of coating layers  112  and  114  measured at all of the thickest portions of the coating pattern along the length and width of tape blade  14 . 
     Coating layers  112  and  114  may be applied as a laminate, nylon extrusion, film attached with adhesive, power/spray on coating. In one embodiment, the coating layer(s) are configured such that even if the steel core were to fracture, the coating layer is configured to contain the steel core and to maintain the integrity of the blade (e.g., the coating will tend not to tear). 
     In various embodiments, tape blade  14  and the tape blade edge designs discussed herein can be utilized to improve tape durability/tear resistance in tapes having a variety of lengths. In specific embodiments, the length of the tape blade is less than 50 feet or more specifically less than 40 feet. In various embodiments, the length of tape blade  14  is between 15 ft. and 40 ft., and in specific embodiments, the length of the tape blade is 35 ft., 30 ft., 25 ft., or 16 ft. 
     As shown in  FIG.  3   , inner core  110  includes a pair of opposing lateral edge surfaces  120 . In the longitudinal cross-sectional view of  FIG.  3   , lateral edge surfaces  120  extend between the upper concave surface and the lower convex surface of inner core  110  and are contiguous with both surfaces. In addition, lateral edge surfaces  120  extend the entire longitudinal length of tape blade  14 . While  FIG.  3    shows coating layers  112  and  114  covering the upper and lower surfaces of tape blade  14  only, in other embodiments, a polymer coating layer surrounds/covers lateral edge surfaces  120 . As will be discussed in more detail below, lateral edge surfaces  120  are configured (e.g., shaped, polished, finished, etc.) to reduce tear initiation and improve durability. 
     Referring to  FIG.  4   , a detailed view of a lateral edge surface  120  of inner core  110  incorporating a tear resistant design is shown according to an exemplary embodiment. It should be understood that while  FIG.  4    shows a single lateral edge surface  120 , both the left and right lateral edge surfaces  120  may incorporate the various durability improving designs discussed herein. As shown in  FIG.  4   , lateral edge surface  120  is shaped to improve tear resistance. In particular, in contrast to typical squared tape blade edge designs, Applicant believes a curved lateral edge surface  120 , such as that shown in  FIG.  4    may improve tear resistance. 
     In various embodiments, lateral edge surfaces  120  include shaped, non-planar surface sections. In specific embodiments, the lateral edge surfaces  120  each include convex curved sections. As shown in the specific embodiment of  FIG.  4   , lateral edge surface  120  is a convex curved surface that extends between the opposing upper and lower surfaces of inner core  110 . In particular, lateral edge surface  120  is a continuous, convex curved surface extending the entire distance between the opposing upper and lower surfaces of inner core  110 . In such embodiments, the curve of surfaces  120  is continuous (e.g., non-interrupted) defining a convex curve that extends the entire distances between upper and lower surfaces of inner core  110 . As will be understood, inner core  110  is formed from a contiguous, integral piece of metal which defines the upper and lower surfaces and the lateral edge surfaces  120 . In some embodiments, the convex curved surface of surface  120  extends the entire length of inner core  110 , and in other embodiments, the convex curved surface of surface  120  is a section extending less than the entire length of inner core  110 . In some such embodiments, the convex curved section of surface  120  is located only in the first 10 feet of length from the hook end of inner core  110 . 
     In particular embodiments, curved lateral edge surface  120  defines an arc having an angle A 1 . In various embodiments, angle A 1  is 180 degrees or less, in specific embodiments, angle A 1  is 45 degrees to 180 degrees and in even more specific embodiments A 1  is 60 degrees to 120 degrees. In various embodiments, curved lateral edge surface  120  is defined by a radius of curvature R 1 . 
     Referring to  FIG.  5   , Applicant believes that other shapes of lateral edge surface  120  may also improve durability of tape blade  14 . In various embodiments, lateral edge surface  120  may have any of the standard American Iron and Steel Institute (AISI) edge shape profiles shown in  FIG.  5   . 
     Referring to  FIG.  6   , instead of or in addition to the edge surface shapes discussed above regarding  FIGS.  4  and  5   , lateral edge surface  120  may also have a design that incorporates a surface finish that improves durability. In particular embodiments, as shown in  FIG.  6   , lateral edge surface  120  may be finished, polished, etc. in a manner that reduces imperfections, defects, surface roughness, etc. that Applicant believes may decrease durability of the tape blade. By comparing  FIG.  6    to  FIG.  8   , the improved surface quality present in lateral edge surface  120  is apparent. 
     In various embodiments, lateral edge surface  120  includes one or more surface characteristics that Applicant believes correlates with improved durability/tear resistance. In various embodiments, lateral edge surfaces  120  have a high surface quality. As noted above, Applicant believes that by reducing the surface defects present in lateral edge surfaces  120 , the durability is improved by reducing the likelihood of tear initiation during whip. 
     In various embodiments, the durability improving design of lateral edge surface  120  (whether the durability improving shapes of  FIGS.  4  and  5    or the surface characteristic(s) of  FIG.  6   ) extend the entire longitudinal length of tape blade  14 . In other embodiments, the durability improving design of lateral edge surface  120  (whether the durability improving shapes of  FIGS.  4  and  5    or the surface characteristic(s) of  FIG.  6   ) extend a portion of the longitudinal length of tape blade  14  in regions more susceptible to tearing. In specific embodiments, the durability improving design of lateral edge surface  120  (whether the durability improving shapes of FIGS.  4  and  5  or the surface characteristic(s) of  FIG.  6   ) extend for the first 10 feet from hook assembly  26 , specifically for the first six feet from hook assembly  26 . 
     In various embodiments, the edge shapes and/or surface finishes discussed herein may be formed via a variety of methods. In various embodiments, the edge shapes and/or surface finishes discussed herein are formed using one or more of grinding, polishing, compressing, molding, melting, or other suitable means. In a specific embodiment, lateral edge surface  120  are produced via a skiving edge forming process. 
     In specific embodiments, at least a section of one or both of lateral edge surfaces  120  is polished such that the number of surface defects on the lateral edge surfaces of the metal core is less than the number of surface defects on the unpolished upper and/or lower surfaces of the metal core  110 . In specific embodiments, the polishing of lateral edge surfaces  120  reduces the number of surface defects such that an average number of surface defects per unit of area (e.g., per mm 2  or per cm 2 ) of lateral edge surface(s)  120  is less than an average number of surface defects per the unit of area of the upper surface of the metal core  110 . 
     It should be understood that the figures illustrate the exemplary embodiments in detail, and it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for description purposes only and should not be regarded as limiting. 
     Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. The construction and arrangements, shown in the various exemplary embodiments, are illustrative only. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention. 
     Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article “a” is intended to include one or more component or element, and is not intended to be construed as meaning only one. 
     Various embodiments of the invention relate to any combination of any of the features, and any such combination of features may be claimed in this or future applications. Any of the features, elements or components of any of the exemplary embodiments discussed above may be utilized alone or in combination with any of the features, elements or components of any of the other embodiments discussed above.