Abstract:
A molded plastic yet structurally rigid tool, such as a level, with a web extending in a generally undulating configuration. The undulating configuration of the web acts to strengthen and make the level more rigid when compared to a level with a planar web. The undulating configuration of the web is substantially symmetrical about the centerline of the level over its entire length, but may also be arranged in a number of non-planar embodiments.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a level, and more specifically to a web configuration for a level. 
   BACKGROUND OF THE INVENTION 
   Leveling and/or plumbing devices, generally referred to as levels, are frequently used in construction or other applications for marking or determining the level or plumb orientation of an object or surface. In many cases, levels are constructed of a material such as wood or metal. To reduce manufacturing costs, and/or to reduce weight, it is also known to construct levels using a moldable material such as fiberglass or plastic. A typical molded level includes a rectangular frame defining a pair of spaced flanges that form the gauging surfaces of the level, a pair of opposing end walls, and a web that interconnects the flanges and end walls. The web is formed with a number of openings within which the measuring or “bubble” vials of the level are mounted. The web may also include openings that act as hand holes to facilitate handling of the level, or for use in hanging the level for storage or transport. Each vial opening may include an opposed pair of notches, slots or recesses, for receiving and securing the ends of one of the vials. 
   Molded frame levels are generally light weight and durable, and typically provide a high degree of accuracy. However, molded levels may not have the structural rigidity found in a metal or wood level due to the inherent strength limitations of the molded material. For this reason, a molded level may flex or twist slightly in response to forces exerted on the frame. This deficiency can be addressed by increasing the web thickness. However, this solution increases the amount of material required to mold the web, thereby increasing the weight and cost of manufacture of the level. 
   In view of the foregoing, it is desirable to provide a molded frame level that minimizes the flexing and twisting that can occur when the level frame is subjected to pressure and force, while maintaining the low cost of manufacture of the level. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a level formed of a moldable material, such as plastic, that is structurally rigid without substantially increasing the amount of material used in its construction. The invention, which is defined by the claims set out at the end of this disclosure, is intended to solve at least some of the problems noted above. In one embodiment, a level is provided with a frame that has an undulating or wave-shaped web over at least a portion of the length of the level frame. The undulating or wave configuration of the web adds strength and rigidity to the level frame when compared to a typical level frame with a planar web. This configuration substantially reduces flexing of the level when the level is subjected to lateral or twisting forces. The web can be designed with any type of undulating or wave configuration including, without limitation, a sinusoidal, triangle or square wave configuration. 

   
     Various other features, objects and advantages of the invention will be made apparent from the following detailed description taken together with the drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout and in which: 
       FIG. 1  is an isometric view of a first embodiment of a level incorporating a web constructed in accordance with the present invention; 
       FIG. 2  is a side elevation view of the level of  FIG. 1 ; 
       FIG. 3  is a top plan view of the level of  FIG. 1 ; 
       FIG. 4  is a bottom plan view of the level of  FIG. 1 ; 
       FIG. 5  is an end elevation view of one end of the level of  FIG. 1 ; 
       FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 1 ; 
       FIG. 7  is an isometric view of a second embodiment of a level incorporating a web constructed in accordance with the present invention; 
       FIG. 8  is a side elevation view of the level of  FIG. 7 ; and 
       FIG. 9  is a sectional view taken along line  9 - 9  of  FIG. 7   
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Before explaining embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments, and may be pracited or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     FIGS. 1-6  show a first embodiment of a tool, such as a level  10 , made in accordance with the invention. The level  10  includes a frame that is formed of an integral piece of molded material such as plastic or fiberglass, although it is understood that the level  10  may be formed of any other satisfactory material. The level  10  includes a frame  11  having a planar top flange  12  and a planar bottom flange  14 , which extend parallel to each other between a pair of opposed end walls  16 ,  18 . A web  20  extends between and interconnects the flanges  12 ,  14  and end walls  16 ,  18 . 
   The level  10  has a generally I-shaped cross section. A curved V-shaped center reinforcement  22  is formed within the level  10 . The center reinforcement  22  creates a gap  28  in the upper flange  12  and in the web  20 . The center reinforcement  22  includes slots or recesses  30  which are configured to receive and engage the ends of a bubble vial  50 , in a manner as is known. 
   As shown in  FIGS. 1-2 , the web  20  is formed with a series of apertures  32 ,  34 ,  36 ,  38 ,  40 , the number and configuration of which can vary as desired, and in accordance with the length of the level  10 . Two of the apertures  34 ,  40  have slots  44 ,  46 , respectively, that are configured to receive and engage the ends of additional bubble vials  52 ,  54 , respectively. In the illustrated embodiment, the slots  44  in aperture  34  are oriented to receive the ends of a bubble vial  52  positioned to extend perpendicular to the longitudinal axis of the level  10 , which is used in a plumbing application, i.e. to gauge the orientation of a surface relative to vertical. The slots  46  in aperture  40  are oriented to receive the ends of a bubble vial  54  positioned at an angle of forty five degrees to the longitudinal axis of the level  10 , which is used to gauge the orientation of a surface relative to an angle of forty five degrees between horizontal and vertical. The larger apertures  36 ,  38  can be used for carrying the level  10  while the smaller aperture  32  can be used to hang the level  10  when not in use. 
   The end walls  16 ,  18  of level  10  extend between and interconnect flanges  12 ,  14 . The end walls  16 ,  18  have a width generally equal to that of flanges  12  and  14 , and are integrally formed with flanges  12 ,  14  and web  20 . 
   In accordance with the present invention, the web  20  has a non-planar configuration.  FIGS. 1 and 6  show the web  20  extending from one end wall  16  to the other end wall  18  in an undulating or generally wave-shaped configuration. In the illustrated embodiment, the web  20  is substantially symmetrical about the longitudinal centerline of the level  10  over its length, although it is understood that an asymmetrical configuration may be employed. With the undulating or wave-shaped configuration, the web  20  provides an increased stiffness to the level  10  over that which is possible with a generally planar web of comparable thickness. 
     FIGS. 7-9  show a second embodiment of a tool, such as a level  110 , made in accordance with the present invention. Similar reference characters (increased by 100) are used in  FIGS. 7-9  as in  FIGS. 1-6  to denote similar components and features. The level  110  of this embodiment is longer than the level  10  of  FIGS. 1-6 . Because of the increased length of the level  110 , the web  120  can have additional apertures without decreasing the strength of the level  110 . Representatively, apertures  136   a  and  136   b  may be located between vials  50  and  52 , and apertures  138   a  and  138   b  may be located between vials  50  and  54 . An additional aperture  140  may be located between vial  52  and end wall  116 , and an additional aperture  142  may be located between vial  54  and end wall  118 . 
   While the present invention has been shown and described with respect to specific embodiments, it is understood that various alternative and modifications are possible and are contemplated a being within the scope of the present invention. For example, and without limitation, the wave-shaped configuration of the web  20  could extend over only a portion of the length of the level  10 , with the remaining portion of the web  20  being generally planar. Alternatively, the web  20  could be comprised of angled linear portions. Also, the web  20  could be comprised of parallel offset web sections on opposite sides of the center of the level  10 . The length of the undulating portions of the web  20  may be uniform throughout the length of the level  10 , or the undulating portions of the web  20  may vary in length. The length of the undulating portions, or the “frequency” of repetition of the undulating portions, may vary from the relatively long length as shown in the drawings to a relatively short length in which the undulations in the web  20  repeat many times over the length of the level  10 . While the level  10  has been shown and described as having bubble vials for the indicating the orientation of the level gauging surfaces, it is understood that any other types of orientation indicating members or components may be used, e.g. digital indicators or the like. In addition, while it is contemplated that the frame  11  of level  10  may be formed integrally of a moldable material in an injection molding process, it is also understood that the frame  11  of the level  10  may be formed of several pieces that are connected together. As an example, the web  20  may be formed of a metal material in a stamping operation, and the flanges  12 ,  14  may be connected to the edges of the web  20 , e.g. via welding. 
   Various alternatives are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.