Top frame with locking features

Abstract

A top frame with locking features is provided. The top frame includes four legs having a top surface and a bottom surface. The top frame includes a first interlocking feature in the form of a plurality of protrusions and a second interlocking feature in the form of indented receptacles on the top surface. The plurality of protrusions can be provided proximate a corner of the top frame and the plurality of indented receptacles can also proximate the corner but spaced from the plurality of protrusions. Each corner of the top frame can include a plurality of protrusions and a plurality of indented receptacles. Each occurrence of the plurality of protrusions and the plurality of indented receptacles can alternate about the top surface of the top frame. The bottom surface can also include the same pattern of locking features.

I claim: 
     
         1 . A top frame with interlocking features comprising:
 a first leg;   a second leg;   a third leg;   a fourth leg, wherein the first leg, second leg, third leg and fourth leg form a generally rectangular shape having an upper surface and an opposing lower surface;   a first plurality of repeating protruding structures positioned at a first location on the upper surface of the top frame; and,   a first plurality of repeating indented receptacles at a first location on the lower surface of the top frame.   
     
     
         2 . The top frame of  claim 1  wherein the first location of the first plurality of repeating protruding structures is proximate a first corner of the top frame. 
     
     
         3 . The top frame of  claim 2  wherein the first location of the first plurality of indented receptacles is proximate the first corner of the top frame and aligned with the first plurality of repeating protruding structures. 
     
     
         4 . The top frame of  claim 3  wherein the first plurality of repeating indented receptacles is a mirrored pattern of the first plurality of repeating protruding structures. 
     
     
         5 . The top frame of  claim 3  further comprising:
 a second plurality of repeating protruding structures positioned proximate a second corner of the top frame on the lower surface of the top frame; and, 
 a second plurality of repeating indented receptacles positioned proximate the second corner of the top frame on the upper surface of the top frame and aligned with the second plurality of repeating protruding structures. 
 
     
     
         6 . The top frame of  claim 1  wherein the first plurality of repeating protruding structures has a saw-tooth cross-sectional shape. 
     
     
         7 . The top frame of  claim 1  wherein a total amount of the first plurality of repeating indented receptacles is greater than a total amount of the first plurality of repeating protruding structures. 
     
     
         8 . The top frame of  claim 1  wherein the top frame includes a plurality of ribs extending from the upper surface to the lower surface. 
     
     
         9 . The top frame of  claim 1  wherein the first leg, second leg, third leg and fourth leg define a generally rectangular opening therebetween. 
     
     
         10 . The top frame of  claim 5  further comprising:
 a third plurality of repeating protruding structures positioned proximate a third corner of the top frame; and, 
 a first plurality of repeating indented receptacles positioned proximate the third corner of the top frame. 
 
     
     
         11 . The top frame of  claim 10  further comprising:
 a fourth plurality of repeating protruding structures positioned proximate a fourth corner of the top frame; and, 
 a fourth plurality of repeating indented receptacles positioned proximate the fourth corner of the top frame. 
 
     
     
         12 . The top frame of  claim 2  further comprising a second plurality of repeating indented receptacles on the upper surface proximate the first corner and proximate the first plurality of repeating protruding features. 
     
     
         13 . The top frame of  claim 1  formed from a molded plastic. 
     
     
         14 . A top frame with interlocking features comprising:
 a first leg having a first end and a second end;   a second leg connected at a first end to the second end of the first leg;   a third leg connected at a first end to a second end of the second leg;   a fourth leg connected at a first end to a second end of the third leg and connected at a second end to the first end of the first leg; the first leg, second leg, third leg and fourth leg having an upper surface;   a first plurality of ridges extending upward from the upper surface at a first location; and,   a first plurality of receptacles extending downward from the upper surface at a second location.   
     
     
         15 . The top frame of  claim 14  further comprising a plurality of ribs extending downward from the top surface. 
     
     
         16 . The top frame of  claim 14  wherein the first location is proximate a first corner of the top frame formed by the first leg and the second leg, and the second location is proximate the first corner and spaced from the first location. 
     
     
         17 . The top frame of  claim 16  further comprising:
 a second plurality of ridges extending upward from the upper surface proximate a second corner formed by the second leg and the third leg; and, 
 a second plurality of receptacles extending down from the surface proximate the second corner and spaced from the second plurality of ridges. 
 
     
     
         18 . The top frame of  claim 14  wherein the first plurality of ridges has a saw-tooth cross-sectional shape, and the first plurality of receptacles has a saw-tooth cross-sectional shape. 
     
     
         19 . The top frame of  claim 15  further comprising:
 a fifth leg having a first end and a second end; 
 a sixth leg connected at a first end to the second end of the fifth leg; 
 a seventh leg connected at a first end to a second end of the sixth leg; 
 an eighth leg connected at a first end to a second end of the seventh leg and connected at a second end to the first end of the fifth leg; the fifth leg, sixth leg, seventh leg and eighth leg having a lower surface and a plurality of ribs extending upward and welded to the plurality of ribs extending downward from the upper surface; 
 a first plurality of ridges extending downward from the lower surface at a first location; and, 
 a first plurality of receptacles extending upward from the lower surface at a second location. 
 
     
     
         20 . The top frame of  claim 14  wherein the top frame is formed from a molded plastic.