US3770237A

US3770237A - Concrete form

Info

Publication number: US3770237A
Application number: US00183200A
Authority: US
Inventors: D Burton
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-09-23
Filing date: 1971-09-23
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06

Abstract

A concrete form useful in forming a key contraction joint between concrete slabs. The concrete form comprises a plurality of spaced-apart, aligned stakes and an elongate rigid sheet material member having upper and lower longitudinally extending, generally coplanar portions and a longitudinally key deformation portion interposed between and connected to said planar portions. At least some of the stakes have a pocket means formed thereon. Each pocket means includes an edge engaging surface. The sheet material member has a plurality of longitudinally spaced strap means formed within one of the planar portions and said member includes a plurality of parts, each part including an edge portion which is disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof to prevent movement of said member in an upwardly direction by utilizing the shear properties of the material from which said member is formed. Each strap means is disposed in partial encompassing engagement about a portion of a corresponding one of said stakes. Each pocket means includes a tab means having a portion thereof biasedly disposed in a direction toward the body portion of its corresponding stakes. Each of the parts of said member has a planform projection, taken in a direction normal to the body portion of the stakes, that is greater than the thickness of the material from which the member is formed.

Description

United States Patent 1 [191 Burton [1 11 3,770,237 1451 Nov. 6, 1973 CONCRETE FORM [76] Inventor: Duane C. Burton, 145 Mohawk Dr.,

Boulder, Colo. 80303 221 Filed: SeptQ'ZS, 1971 211 Appl. No.: 183,200.

Related U.S. Application Data [63] Continuation-impart of Ser. No. 12,611, Feb. 19,

1970, abandoned.

[52] U.S. Cl. 249/3 [51] Int. Cl. E0lc 7/00 [58] Field of Search 249/3, 2, 5, 9, 98, 249/100, 219; 52/150; 94/17, 51

[56] References Cited UNITED STATES PATENTS 3,497,172 2/1970 Welch 249/3 3,561,721 2/1971 Self... 249/3 X 3,288,042 11/1966 Gaetke 24913 X 3,057,269 10/1962 Artigalas et al.... 249/9 X 3,628,764 12/1971 Burton 249/9 Primary Examiner-41. A. Kilby, Jr.

[ 5 7] ABSTRACT A concrete form useful in forming a key contraction joint between concrete slabs. The concrete form comprises a plurality of spaced-apart, aligned stakes and an elongate rigid sheet material member having upper and lower longitudinally extending, generally coplanar portions and a longitudinally key deformation portion interposed between and connected to said planar portions. At least some of the stakes have a pocket means formed thereon. Each pocket means includes an edge engaging surface. The sheet material member has a plurality of longitudinally spaced strap means formed within one of the planar portions and said member includes a plurality of parts, each part including an edge portion which is disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof to prevent movement of said member in an upwardly direction by utilizing the shear properties of the material from which said member is formed. Each strap means is disposed in partial encompassing engagement about a portion of a corresponding one of said stakes. Each pocket means includes a tab means having a portion thereof biasedly disposed in a direction toward the body portion of its corresponding 1 stakes. Each'of the parts of said member has a planform projection, taken in a direction normal to the body portion of the stakes, that is greater than the thickness of the-material from which the member is formed.

8 Claims, 10 Drawing Figures PATENTED NOV 6 \973 IN VE N TOR DUANE C. BURTON l CONCRETE FORM CROSS-REFERENCE TO RELATED APPLICATION- This is a continuation-in-part patent application of US. Pat. application Ser. No. 12,611 filed Feb. 19, 1970 now abandoned.

BACKGROUND OF THE INVENTION Heretofore, many concrete forms have been proposed comprising the use of a plurality of spaced-apart, aligned stakes which are used to support a sheet material member having a configuration suitable to form a longitudinally extending key contraction joint between concrete slabs. Although some of the prior art concrete forms found useful application in the field, each of these forms suffered from one or more drawbacks. For example, some of the concrete forms were expensive to manufacture, others could not be easily and quickly installed by a single individual in the field, others lacked an inexpensively constructed means quickly and easily used for preventing vertical movement of the sheet material member relative to the stakes during the pouring of the concrete, others experienced undesirable cracking and spalling along the upper surface of the concrete slab adjacent the top of the sheet material member, and others could not be used in concrete slabs which had to support heavy vehicle wheel loads. It has been discovered, however, that each of the foregoing disadvantagescan be overcome through the use of a concrete form comprising a plurality of spaced-apart, aligned stakes, at least some of which have a pocket means formed thereon, each of said pocket means including an edge engaging surface, and an elongate rigid sheet material member having strap means formed therein, each of said strap means being disposed in partial encompassing engagement about a corresponding one of said stakes, said member also including a plurality of parts, each part including an edge portion which is disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof whereby said pocket means utilizes the shear characteristics of the material from which said member is made to secure said member to prevent undesirable vertical movement thereof relative to the stakes.

SUMMARY-OF THE INVENTION This invention relates to a concrete form of a type used in forming a key contraction joint between concrete slabs wherein said joint comprises a plurality of spaced-apart aligned stakes, each of said stakes having a generally vertically disposed body portion and a top, at least some of said stakes having a pocket means formed thereon, each of saidpocket means including an edgeengaging surface, each of said stakes adapted to be driven to a predetermined height so that the tops thereof are disposed along a'predetermined grade level; and an elongate rigid sheet'material member having upper and lower longitudinally extending, generally coplanar portions and a longitudinally extending key de-' formation portion interposedbetween and connected to said planar portion, said member having a plurality of longitudinally spaced strap means formed within one of said planar portions, the spacing of said strap means corresponding to the longitudinal spacing of said stakes, each of said strap means being disposed at least in partial encompassing engagement about a portion of a corresponding one ofsaidjstakes, said member including a plurality of parts, each part including an edge portion which is disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof, said pocket means utilizing the shear characteristics of the material from which the member is made to secure said member to prevent vertical movement thereof relative to said stakes, said strap means securing said member to prevent horizontal movement thereof relative to said stakes. Each pocket means includes a tab means having a portion thereof biasedly disposed in a direction toward the body portion of its corresponding stake. The edge engaging surface is preferably formed on said tab means. Each tab means of each pocket means, during installation of said parts of said member within said pocket means, is adapted to move away from the body portion of its corresponding stake. Each of the parts of said member disposed within said pocket means has a planform projection, taken in a direction normal to the body portion of said stakes, that is thicker than the thickness of the material from which the member is formed. Each strap means is, in vertical cross-section, generally C-shaped in configuration and a portion of each strap means may include one of the parts of said member. Each edge engaging surface of each pocket means is formed to lie in a plane that intersects a plane disposed normal to the longitudinal axis of the associated stake to form an included angle the tangent of which is less than the coefficient of friction between said edge engaging surface and said edge portion.

Accordingly, one of the principal object of this invention is to provide an improved concreteform.

Another object of this invention is to provide a concrete form that is inexpensive to manufacture, may be quickly and easily installed by a single individual in the field, includes novel, inexpensive means for securing the member to the stakes, utilizes the shear properties of the material used to make said member to prevent undesirable vertical movement of said member relative to said stakes, uses strap means to secure said member to prevent horizontal movement thereof relative to said stakes, and permits the construction of concrete slabs which may be used to support heavy vehicles wheel loads without-spalling or crackingoccurring adjacent the concrete form installed therein.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention will become apparent from the following description and claims andfrom the accompanying drawings, wherein:

FIG. 1 is an end elevational view of a preferred embodiment. of the concrete form constructed in accordance with the subject invention;

FIG. 1A is an enlarged view illustrating the edge por- FIG. 6A is an enlarged view illustrating the edge portion and edge engaging surface of the concrete form shown in FIG. 6;

FIG. 7 is a view similar to that shown in FIG. 1 of another embodiment of a concrete form constructed in accordance with the subject invention; and

FIG. 8 is a partial cross-sectional view showing a portion of another concrete form.

DESCRIPTION OF TI-IEPREFERRED EMBODIMENTS Referring now to the drawings, in FIGS. l is shown one embodiment of a concrete form 12 constructed in accordance with the subject invention. The concrete form 12 is of the type used in forming a key contraction joint between adjacent concrete slabs (not shown) and comprises a plurality (only one of which is shown) of spaced-apart, alignedstakes l4 and an elongate rigid sheet material member 16. Each of the stakes 14 has a generally vertically disposed body portion 18 and a top 20. At least some of the stakes have a pocket means 22, see FIG. 1, formed thereon. Each pocket means 22 includes one or more tab means 24. Each tab means 24 includes an edge engaging surface 25, see FIG. 1A. Each tab means 24 has a portion 26, see FIG. 1, biasedly disposed in a direction toward the body portion 18 of the stake 14. Each tab means 24 of each pocket means 22 is adapted to move away from the body portion 18 during installation of the member 16 as will hereinafter be described. Each of the stakes 14 is adapted to be driven to a predetermined height so that the tops thereof are disposed along a predetermined grade level.

The elongate rigid sheet material member 16 has upper and lower longitudinally extending, generally coplanar

portions

28 and 30 and a longitudinally extending key deformation portion 32 interposed between and connected to said

planar portions

28 and 30. The member 16 has a plurality of longitudinally spaced strap means 34 (only one of which is shown) formed within one of said planar portions. The spacing of said strap means 34 corresponds to the longitudinal spacing of said stakes 14. Each of said strap means 34 is disposed at least in partial encompassing engagement about a portion of a corresponding one of said stakes. The member 16 includes a plurality of parts 36 (only one of which is shown), see FIGS. 1 and 1A. Each of said parts includes an edge portion 37 which is disposed within a corresponding one of said pockets 22 to contact the edge engaging surface thereof whereby said 7 pocket means utilizes the shear properties of the mateof intersecting surfaces disposed normal one to the other wherein one of said surfaces is disposed parallel to the body portion of its corresponding stake. It will be understood that each edge engaging surfaceof each pocket means is formed to lie in a plane that intersects a plane disposed normal to the longitudinal axis of its associated stake to form an included angle the tangent of which is less than the coefficient of friction between said edge engaging surface and said edge portion. The use of a larger angle is to be avoided if the shear properties of the material used to form the member is to be utilized. The strap means 34 and the pocket means 22 cooperate to secure the member 16 to prevent horizontal movement thereof relative to the stakes 14.

As shown in FIG. 5, the strap means 34 preferably is, in vertical cross-section, generally C-shaped in configuration. The formation of the strap means 34 in this configuration facilitates the mounting of the member 16 upon the stakes 14 since the lower portion of the strap means 34 extends outwardly from the stake 14. The sheet material member 16 preferably has folded over

portions

38 and 40 adjacent, respectively, the upper and

lower edges

42 and 44 of said sheet material member 16. Said sheet material member 16 also includes a longitudinally extending corrugation 'or rib 46 located in the upper planar portion. The purpose of utilizing the folded over

portions

38 and 40 and the longitudinally extending corrugation 46 is to increase the overall rigidity of the member 16.

As shown in FIG. 1, the thickness or planform projection, taken in a direction normal to the body portion 18 of the stake 14, of the part 36 is greater than the thickness of the material from which the member is formed as well as the horizontal distance separating the portion 26 of the tab means 24 from the adjacent body portion 18. Normally, the horizontal distance separating the portion 26 of the tab means from the adjacent body portion 18 is less than the thickness of the material from which the member 16 is made. In view of the construction of the pocket means 22 and each part '36 of said member coupled with the further fact that the portion 26 is biased in a direction toward the adjacent body portion 18, it will now be readily appreciated that the pocket means 22 and the part 36 cooperate to prevent vertical movement of the member 16 relative to the stakes 14. As a' result, a concrete form constructed in accordance withthis invention overcomes, through the use of an inexpensive and novel means, the problem heretofore encountered of the sheet material member 16 rising vertically upwardly relative to the stakes 14 during thepouring of the concrete on one side of. the form 12 such as when concrete is poured on the right side of the concrete form 12 shown in FIG. 1.

A concrete form 48 is shown in FIGS. 6 and 6A which is similar to the concrete form 12' shown in FIG. 1 except that each pocket means 50 and its corresponding edge engaging surface 51 formed on the stake 52 is located immediately below the top 54 of the stake. Secured within each pocket means 50 is a portion of the strap means 34. As a result, it will be understood that said portion of the strap means 34 includes one of the parts 56 of the member 16 and each of the parts 56 includes an edge portion 57.

In FIG. 7 is shown concrete form 60 which is similar to concrete form 48' shown in FIG. 6. However, the portion 62Iof the tab means 64 seats within the concave surface of the strap. means 66 and a lower portion of the strap means 34 includes one of the part 68 of the member 70. It will also be noted that the lower planar portion 72 and the member includes a longitudinally extending corrugation or rib 74 in lieu of the foldedover portion '40 as shown in FIG. 1 for m'ember'16. However, it will be understood that a folded over portion may be used in lieu of or in combination with the longitudinallyextending corrugation 74.

Referring now to FIGS. 1-5, the installation of the concrete form 12 as shown in FIG. 1 is now described. After the subgrade or sub-base (not shown) has been formed and suitable side forming (not shown) has been installed, a string or line .(notshown) is extended from one side ofthe sub-base to the other side thereof at a predetermined grade level, preferably the grade level to be associated with the tops of the stakes 14. Next, a section or sections of joint forming members 16 are laid adjacent the line established by the string. The purpose for this is to facilitate the spacing of the stakes along the line established by the string. However, it will be appreciated that the spacing may be determined in any of several other ways since the spacing between the strap means 34 will admit of some variation in installation thereby precluding an exact, precise spacing of the stakes. For example, where 'a' 2 foot spacing interval is desired or required, the length of the strap means 36 is made sufficiently long to permit center-to-center spacing between the strap means 34 to vary up to approximately 4 to 5 inches. After the member or members 16, depending on the width of the concrete slabs, are positioned upon the subgrade as described, the stakes are installed one at a time along the line established by the string at the desired spacing interval. Each stake 14 is driven into the subgrade until the top thereof is disposed along a predetermined grade level. Next, each of the members 16 is mounted upon the stakes 14 by positioning the member 16 with the lower edge of 44 thereof disposed adjacent the part 76 which is above the portion 26 of the tab means 24 and with the strap means 34 disposed above the tops 20 of the stakes 14. The member 16 is then urged downwardly with sufficient force such that the parts 36 pass between the portion 26 of-the tab means 24 and the adjacent body portion 18 of the stake 14 and each strap means 34 encompasses a corresponding one of the stakes 14. When the upper surface of the folded over portion 44 moves below the portion 26 of the tab means 24, the portion 26 moves toward the adjacent body portion 18 thereby securing the part 36 within the pocket means 22. In this manner, the member 16 is easily and quickly mounted upon the stakes 14 and secured relative thereto to prevent undesirable movement either horizontally or vertically relative to said stakes 14. It will be noted that the part 76 of the tab means 24 extends upwardly from the portion 26 of the said tab. means 24 and,.proceeding vertically upwardly, diverges away .from the adjacent body portion 18 of the stake 14. This construction facilitates the positioning and the entry of part 36 into the pocket means 22.

The distance separating the top 20 of the stake l4 and the portion 26 of the tab means preferably equals the distance separating the lower edge 44 of the member 16 and the lower surface strap means 34 whereby the strap means 34 passes around the stake l4 substantially at the same time the part 36 enters into the pocket means 22. This minimizes the tendency of the member 16 to buckle or deform upon being mounted on the stakes 14.

The installation of the

concrete forms

48 and 60 as shown in FIGS. 6 and 7 is substantially similar to the installation of the concrete form 12 shown in FIG. 1 except, of course, no problem exists with respect to coordinating the disposition of the

parts

56 or 68 within the pocket means relative to the time the strap means 34 is slipped over the stakes since the

parts

56 or 68 become disposed within the pocket means following the time that the strap means 34 is slipped over the tops of the stakes.

Normally, the height of the strap means 66 exceeds the height of the strap means 34 and the depth of the pocket means 78, see FIG. 7, is less than the depth of the pocket means 50 of the concrete form 48 shown in FIG. 6.

It will be understood that the upper and lower planar portions 28'and 30 of the member 16 shown in FlG. 1 are readily maintained against the adjacent side of the stake 14. In the

concrete forms

48 and 60 the upper and lower planar portions are also maintained against the adjacent side of the stakes; however, the lower planar portions of said members are better maintained against the adjacent side of the stakes where one part of the key deformation portion is biasedly urged toward another part of said key deformation portion. To effect this, the upper and lower planar portions of such a member are, prior to installation of the member upon the stakes, not coplanar; since said upper and lower planar portions are disposed within separate planes, the extensions of which form an included angle of slightly less than 180. However, upon mounting such a member upon a set of stakes, said upper and lower planar portions become generally coplanarly disposed.

In FIG. 8 is shown a portion of another concrete form constructed in accordance with this invention. The concrete form 80 comprises a sheet material member 82 having a plurality of longitudinally extending apertures 84 (only one of which is shown) formed in the lower planar portion 86 thereof. The portion 26 of each tab means 24 is disposed within a corresponding aperture 84. The horizontal distance separating the portion 26 from the adjacent body portion 18 of the stake 14 is less than the thickness of the material from which the member 82 is formed. The portion 26 is biasedly disposed in the same manner as described above in connectionwith the stake 14 shown in concrete form 12. The part of member 82 disposed within the pocket formed on the stake has an edge'portion 83 disposed to contact the edge engaging surface 25 as described above in connection with'FlG. I. Said part of member 82 may include a longitudinally extending rib (not shown) to facilitate mounting of the'member 82 on the stakes'without buckling. With this construction, the apertures 84'are formed in the upper portion of such a rib. Concrete form 80 is installed much in the same manner as concrete form 12'shown in FIG. 1.

Although several embodiments of the herein invention have been shown and described; at the present time the concrete form 12 shown in FIG. 1 is the preferred concrete form while the concrete form 48 shown in FIG. 6 is the next preferred embodiment of this invention.

In view of the foregoing, it will now be readily apparent that a vastly improved concrete form has been described. F or example, it will be readily appreciated that a concrete form has been described which may be quickly and easily installed in the field by a single individual and that same may be used for monolithically poured concrete slabs without resort to checkerboard pouring. Further, concrete forms constructed in accordance with the subject invention may be used for relatively thick concrete slabs, i.e., 8 inches or more, without experiencing detrimental spalling or cracking thereof adjacent the upper surfaces of the concrete form. Additionally, concrete forms constructed in accordance-with the subject invention provide inexpensive, novel means. for securing the sheet material member to the stakes to prevent vertical movement thereof relative to the stakes thereby assuring that the upper edge of such sheet material member is properly positioned to function as a screed following pouring of the concrete. Also, concrete forms constructed in accordance with the subject invention may be used in conjunction with concrete slabs which are subjected to relatively heavy loading, and beneficial results are obtained for both relatively thick concrete slabs and relatively thin concrete slabs.

It is to be understood that this invention is not limited to the exact embodiments of the concrete forms shown, which are merely by way of illustration and not limitation, as various other forms and modifications will be apparent to those skilled in the art. For example, the tops of the stakes and the upper edge of the member may be installed at the same grade level. Further, the member is normally formed from sheet metal but may be formed from plastic as well. Also, it will be understood that the friction developed between the stakes and the strap means will further assist in preventing vertical movement of the member relative to the stakes.

I claim:

1. A concrete form of the type used in forming a key contraction joint between concrete slabs, said joint comprising:

a plurality of spaced-apart, aligned stakes,

each of said stakes having a generally vertically disposed body portion and a top,

at least some of said stakes having a pocket means formed thereon,

each pocket means including a tab means,

each of said tab meanshaving an edge engaging surface formed thereon,

each tab means having a portion thereof biasedly disposed in a direction toward the body portion of its corresponding stake,

each of said stakes adapted to be driven to a predetermined height so that the tops thereof are disposed along a predetermined grade level; and

an elongate rigid sheet material member having upper and lower longitudinally extending, generally co-planar portions and a longitudinally extending key deformation portion interposed between and connected to said co-planar portions,

said member having a plurality of longitudinally spaced strap means formed within one of said planar portions,

the spacing of said strap means corresponding to the longitudinal spacing of said stakes,

each of said strap means being disposed at least in partial encompassing engagement about a portion of a corresponding one of said stakes,

said member including a plurality of parts each of which is disposed within a corresponding one of said pocket means,

each of said parts including an edge portion,

said edge portion being formed by a pair of intersecting surfaces disposed normal one to the other wherein one of said surfaces-lies in a plane disposed generally parallel to the body portion of its corresponding stake,

each edge portion being disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof thereby resisting movement of said member in an upwardly direction by utilizing the shear properties of the material from which said member is formed,

the horizontal distance separating the portion of said tab means and the adjacent body portion of its corresponding stake being less than the thickness of the part disposed within the pocket means associated with each said tab means.

2. A concrete form as described in claim 1 in which each tab means of each pocket means, during installation of said parts of said member within said pocket means, is adapted to move away from the body portion of its corresponding stake.

3. A concrete form as described in claim 1 in which each part has a planform projection, taken in a direction generally normal to the body portion of said stakes, that is thicker than the thickness of the material from which the member is formed.

4. A concrete form as described in claim 1 in which each strap means is, in vertical cross-section, generally C-shaped in configuration and a portion of each strap means includes one of the parts of said member.

5. A concrete form as described in claim 1 in which each edge engaging surface is disposed to lie in a plane that intersects a plane disposed normal to the longitudinal axis of its associated stake to form an included angle the tangent of which is less than the coefficient of friction between said edge engaging surface and said edge portion.

6. A concrete form as described in claim 1 in which 'said strap means are formed within said upper planar 8. A concrete form as described in claim 1 in which said sheet material member includes a plurality of longitudinally spaced apertures formed within the lower planar portion, and the portion of each tab means is disposed within a corresponding one of said apertures.

: UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I, Patent No. 3,77 37 Dated November 6, 1973 Inventor-(s) Duane b Burton It is certified that error appears in thevaboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, Line #2, "members" should'read member -T Signed andnsea led this 29th: day iof October 1974.

(SEAL) Attest: v 'McCOY M. GIBSON JR. 'c'. MARSHALL DANN Attes ting'offi cer Commissioner of Patents FORM PO-105O (10-69) UsCOMM-DC 6OS76-P69 w u. s. GOVERNMENT PRINTING OFFICE "I! 0-366-334,

Claims

1. A concrete form of the type used in forming a key contraction joint between concrete slabs, said joint comprising: a plurality of spaced-apart, aligned stakes, each of said stakes having a generally vertically disposed body portion and a top, at least some of said stakes having a pocket means formed thereon, each pocket means including a tab means, each of said tab means having an edge engaging surface formed thereon, each tab means having a portion theReof biasedly disposed in a direction toward the body portion of its corresponding stake, each of said stakes adapted to be driven to a predetermined height so that the tops thereof are disposed along a predetermined grade level; and an elongate rigid sheet material member having upper and lower longitudinally extending, generally co-planar portions and a longitudinally extending key deformation portion interposed between and connected to said co-planar portions, said member having a plurality of longitudinally spaced strap means formed within one of said planar portions, the spacing of said strap means corresponding to the longitudinal spacing of said stakes, each of said strap means being disposed at least in partial encompassing engagement about a portion of a corresponding one of said stakes, said member including a plurality of parts each of which is disposed within a corresponding one of said pocket means, each of said parts including an edge portion, said edge portion being formed by a pair of intersecting surfaces disposed normal one to the other wherein one of said surfaces lies in a plane disposed generally parallel to the body portion of its corresponding stake, each edge portion being disposed within a corresponding one of said pocket means to contact the edge engaging surface thereof thereby resisting movement of said member in an upwardly direction by utilizing the shear properties of the material from which said member is formed, the horizontal distance separating the portion of said tab means and the adjacent body portion of its corresponding stake being less than the thickness of the part disposed within the pocket means associated with each said tab means.

6. A concrete form as described in claim 1 in which said strap means are formed within said upper planar portion of said member, and said parts of said members are disposed within said lower planar portion of said member.

7. A concrete form as described in claim 6 in which each part has a planform projection, taken in a direction normal to the body portion of said stakes, that is thicker than the thickness of the material from which the member is formed.

8. A concrete form as described in claim 1 in which said sheet material member includes a plurality of longitudinally spaced apertures formed within the lower planar portion, and the portion of each tab means is disposed within a corresponding one of said apertures.