Compressible Coverings For Athletic And Gymnastic Use

Abstract

A gymnastic or athletic floor covering or mat employs compressible or shock absorbing material secured to sheet material to form a laminate by fastening means which present little or no protrusion upon compression of the shock absorbing material. The invention has a particular application in the construction of gymnastic mats employing adjacent blocks of compressible material and flexible sheet covers. The fastening means in its preferred form consists of an integral, elastomeric member having a shank provided with headed ends. The length of the shank is such that upon insertion of the member through the mat, the underside of one of the heads engages the outer face of the bottom cover and that of the other head the upper face of either the compressible material or the top cover so that in either event the shank is maintained in an axially elongated condition. Thus, the compressible material and at least one of the covers are held in a tight laminate relationship and vertical displacement of the blocks of compressible material relative to each other is prevented. When the region of the mat immediately adjacent the device is compressed, as by the weight of a performer thereon, the device contracts therewith rather than protrudes therefrom. Additionally, the lower head frictionally engages the floor to prevent slipping of the covering or mat.

Description

BACKGROUND OF THE INVENTION

Modern gymnastic mats, especially those for tumbling, typically use blocks of polyethylene foam or similar shock absorbing material, sandwiched between fabric covers. Polyethylene foam, however, is readily available only in strips of limited width, usually 1-foot wide. Hence, in order to make up a typical mat section, say, 4 .times. 6 foot, four 6-foot lengths of foam blocks must be placed side-by-side and then prevented in some manner from being displaced relative to each, such as by one block riding up on or over its neighbor. One customary way of preventing such displacement is to join adjacent blocks by some suitable adhesive. But this is often not too secure a method. Another more desirable technique, is to sew the top cover to the bottom such that a series of adjacent compartments or envelopes are formed in each mat section, each compartment or envelope receiving one block of foam. This has the disadvantage, however, of leaving crevices in the top cover between adjacent blocks and furthermore adds to the cost of production of the mats. Accordingly, an important object of the present invention is to provide an improved manner of constructing mats using blocks of lightweight shock absorbing filler material to eliminate the need for adhesively adjoining adjacent blocks of the filler material or the need to provide separate compartments therefor in each mat section.

SUMMARY OF THE INVENTION

The foregoing object and others are achieved by fastening the adjacent mat filler blocks to one or both of the two covers by a fastening device which consists, in its preferred form, of an integral elastomeric member having a central shank portion and a flattened head retaining portion at each end thereof. The device is simply inserted through the mat in one of two manners. In one case the device passes through the bottom cover and the mat filler but not through the top cover; in the other, the device also passes through the latter cover. In either case, the heads of the device capture the mat filler and at least the bottom cover therebetween. The special feature of the mat thereby produced lies in the elastomeric shank of the device whose length is sized such that when so inserted the shank is stretched axially and maintained in that condition by the mat. The length of the shank is such that when the device is in position the shank is stretched sufficiently to prevent it "bottoming out" when the mat is compressed in the immediate vicinity of the device by a performer thereon. Thus, since the shank contracts with the mat when the latter in the immediate area concerned is compressed, it offers no protrusion or "lump" to be felt by the performer.

Equally important, the device eliminates the need adhesively to join adjacent blocks of foam filler or to provide separate envelopes or compartments therefor. It is only necessary, for instance, to sew the top cover to the bottom on three sides to form one large envelope, slip in the necessary number of foam blocks and then sew the remaining side. One or both covers of the mat, depending upon in which of the two manners the fastener is applied, are then secured to the foam blocks by spaced pairs of the foregoing fasteners along the joint between adjacent blocks of foam, each pair of fasteners straddling the joint. Hence, an unbroken top mat surface can be provided, the foam filler blocks positively located relative to each other, and the cost of mat production greatly reduced.

In order to aid insertion of the fasteners, the shank is preferably formed with a hollow core opening through one of the heads, while the other head is pointed and made lesser in diameter than the former or larger head. A driver, in the form of a blunt-ended rod, is inserted therein against the closed end of the core in the pointed head while the larger head is pulled along the driver to stretch the shank. The pointed head is then inserted from the bottom side of the mat through prelocated holes or punctures therein until it emerges on the other side, this being feasible since the elastomeric nature of the device permits the pointed head momentarily to deform sufficiently to allow its passage through the mat. The larger head is then released and the driver withdrawn, permitting the shank partially to contract and the two heads tightly to bind the filler to one or both of the covers, as the case may be. The foregoing operation can be quickly and easily accomplished either manually or by machine.

Preferably, the head of the fastener through which the hollow core of the shank opens is placed on the bottom of the mat and made of sufficient diameter so that it does not wholly withdraw beneath the bottom plane of the mat but instead contacts the floor. This head thus tends to grip the floor when weight is placed upon the mat by a performer and so tends to prevent skidding of the mat thereon. This is an additional benefit accruing from the foregoing construction because such skidding has been a disadvantage of the lightweight-type mat in some instances. Certain other applications and advantages of the present invention will be mentioned in connection with the more detailed description which follows hereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a typical lightweight gymnastic mat section illustrating one form of the present invention.

FIG. 2 is a vertical section taken along the line 2--2 of FIG. 1.

FIG. 3 is an isometric view of a fastening device according to the present invention.

FIG. 4 is a side elevation of the fastening device of FIG. 3.

FIG. 5 is an enlarged transverse section taken along the line 5--5 of FIG. 1.

FIG. 6 is an isometric view of a portion of the mat section illustrated in FIG. 1 illustrating the manner in which the fastening devices of FIGS. 3 and 4 are applied.

FIG. 7 is a view similar to FIG. 5 but illustrating another form of the present invention in a mat section of the nature shown in FIG. 1.

FIG. 8 is a transverse sectional view of a portion of a mat section of the general nature shown in FIG. 1 illustrating still another form of the present invention.

FIG. 9 is a cross-sectional view illustrating an application of the present invention to a laminate of compressible material sandwiched between two rigid covers.

FIG. 10 is likewise similar to FIG. 9 and illustrates another application of the present invention to padding for walls or athletic or gymnastic equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate, as an example of the present invention, a lightweight gymnastic mat section 4 .times. 6 foot, a size typically employed in tumbling, several such sections being joined together end to end for that purpose in any suitable manner, a preferred such manner being disclosed in U.S. Pat. No. 3,242,509 to Nissen. Each such mat section 10 includes a bottom cover 11 and a top cover 12 together with four blocks of shock absorbing filler material 13, each 1 foot wide by 6 foot long laid side by side. The covers 11 and 12 are preferably of nylon fabric impregnated with a polyvinyl resin, and the fillers 13 a polyethylene foam, such as that sold under the trademark ETHAFOAM. The bottom cover 11 is cut slightly larger than the 4 .times. 6 foot dimension of the finished mat, and the top cover is secured thereto, as by sewing a lap seam 14 along each end 15 and one side 16 in the manner illustrated in FIG. 2, the remaining side 17 being left open, in order to form an envelope of the 4 .times. 6 foot dimensions of the finished mat section and of a thickness equal to that of the foam filler blocks 13. Next, the latter are slid into place and the remaining side 17 sewn closed in the manner of the other three. To this extent construction of the mat sections 10 is quite conventional. The foam filler blocks 13 are then secured to the bottom cover 11 or the two covers 11 and 12, as the case may be, by the fastening devices next to be described.

Each such device is illustrated in detail in FIGS. 3 and 4 and comprises an integrally molded, elastomeric member 20 having a cylindrical connecting portion or shank 21 and an enlarged circular retaining portion or head at each end. One of the heads 22 is rounded on its outer end and somewhat larger in diameter than the other head 23 which is pointed at its outer end. The inner faces of each head 22 and 23 are provided with opposed flat shoulders 24 perpendicular to the axis of shank 21. In addition, the latter is molded with a hollow core 25 having one end opening axially through the head 22 at 26 and its other end terminating within the head 23 at 27.

As mentioned, each fastener 20 is applied to the mat section 10 in one of two manners. The first is illustrated in FIG. 5 and may be referred to as the "blind" form. The mat section 10 is inverted and the location of each fastener 20 is determined on the bottom cover 11. Then at each such location a pair of small crosscuts 28 are made in the bottom cover 11 and a sharp instrument, such as an awl, is inserted therein and through the foam filler block 13 therebelow but not through the top sheet 12. Next, the blunt end of a rodlike driver 29, having a T-handle 30, is inserted into the hollow core 25 of a fastener 20 through the open end 26 and seated on the end face 27 in head 23. The head 22 is then pulled up the driver 29, see FIG. 6, stretching the shank 21 and deforming the head 23 as shown. The pointed end of the latter is then plunged through the crosscuts 28 and the foam block 13 until the head 23 emerges on the other side of the foam block 13 beneath the top cover 12. It is helpful for easy insertion of the head 23 if it is first dipped in a suitable lubricant. The head 22 is then released and the driver 29 withdrawn. Accordingly, the shank 21 contracts and the resulting assembly then appears as illustrated in FIG. 5, the bottom cover 11 being tightly secured to the foam block 13 while the top cover 12 remains smooth and unbroken. The latter feature is of particular importance in the case of wrestling or free exercise mats and these, too, can be fashioned in a similar manner using fasteners 20 in the "blind" form of their application, thus eliminating the need of an additional overall cover in order to provide a smooth, unbroken top surface.

"Billowing" of the top cover 12, at least in the case of the smaller mat sections, is usually not a significant problem, but if it should be in some instances, or in the case of larger mat sections, several or all of the fasteners 20 may be utilized in the second form of application illustrated in FIG. 7. There, a fastener 20 is shown passing through the top cover 12 as well, the latter being prepared therefor in the same manner described above for the bottom cover 11, so that the head 23 is exposed. The exposed heads 23 are not as objectionable in the case of mats for tumbling purposes as they may be in the case of mats for other purposes, especially wrestling.

The number and location of the fasteners 20 depend, obviously, upon the size and nature of the mat section itself. For a mat section of the 4 .times.6 foot size shown in FIG. 1, three such fasteners spaced equally down the longitudinal centerline of each foam block 13 should be sufficient and is the example illustrated. If the foam blocks 13, instead of being merely butted against each other, were provided with lap joints, as illustrated in FIG. 8, a single row of fasteners 20 passing through the overlapping portions of the two adjacent blocks 13 will do the job. Here again the "blind" form may be used or the fasteners 20 may also pass through the top cover 12. The important thing, in any event, is that the adjacent foam blocks 13 be held from shifting vertically relative to each other and this is most effectively accomplished by the fasteners 20 which "tie" the blocks 13 tightly to the bottom cover 11, and additionally to each other, in the case of the construction of FIG. 8. It will be readily apparent that whatever the application, location of the fasteners 20 may be determined, and the aperturing of the cover 11 or the covers 11 and 12, as the case may be, be done, before the foam blocks 13 are inserted, or the entire operation, including the insertion of the fasteners 20, may be done by machine.

The heads 23, whether hidden or exposed, do not provide any obstruction to performers since contraction of the shanks 21 causes the heads 23 to sink below the effective top surface of the mat, as illustrated in FIGS. 5 and 7. The heads 22 beneath the mat are large enough so that they partially project below the bottom plane of the mat and thus lightly contact the floor when the mat section is positioned for use. The contact is insufficient to impede sliding the mat along the floor when no weight is upon it, but once a performer is thereon, the heads 22 tend to grip the floor and prevent skidding of the mat. This, as explained, is an additional significant advantage afforded by the fasteners 20, and, of course, the more fasteners that are employed the better the grip of the mat on the floor during use.

As has already been mentioned, the effectiveness of the fasteners 20 lies in both the axial contraction of their shanks 21 upon insertion and in the fact that the contraction is only partial. Thus, when a performer steps upon or otherwise contacts one of the heads 23, or the mat in that immediate vicinity is compressed, the shanks 21 further contract with the compression of the mat. Hence, the fasteners 20 present no obstructions or protrusions to interfere with the performer; indeed, it is nearly impossible to feel them at all in these circumstances. In order to achieve this most important feature of the construction, the length of the shanks 21 must be short enough so that after insertion they do not "bottom out" upon compression by a performer. The factor determining the length of the shanks 21 is, of course, the normal thickness of the uncompressed mat itself and its compressibility. In the case of the lightweight mats of the nature illustrated, which are approximately 1-1/2 inches thick, a shank length unstretched of about 1/2 inches between the faces 24 has proved very satisfactory. Other dimensions of the fasteners illustrated which have been found satisfactory are: diameter of the shank seven-sixteenths inch; diameter of the hollow core 25: three-sixteenth inches; and diameters of heads 22 and 23: 1 inches and seven-eighths inch, respectively. None of the foregoing dimensions, however, is critical and those appropriate for a particular mat or application can readily be determined by one skilled in the art. The material of the fastener 20 is likewise not critical, being, as mentioned, merely a suitable elastomeric one; natural rubber of 40-50 durometer has been used with good results.

Another application of the fasteners 20 is illustrated in FIG. 9. There, a compressible filler 40 is sandwiched between two rigid sheets 41 and 42, the fasteners 20 maintaining the parts in tight laminate relation even when the filler 40 is compressed. Another application is shown in FIG. 10 which illustrates resilient or compressible padding 50, covered by a flexible sheet 51, secured to a rigid base member 52 by a fastener 20.

Through the present invention has been described in terms of particular embodiments thereof, being the best modes known of carrying out the invention, and detailed descriptive language has been used, it is not so limited. Accordingly, the following claims are to be read as encompassing all modifications and adaptations of the invention falling within the spirit and scope thereof.

Claims

I claim:

1. In a compressible floor covering for athletic and gymnastic use having a laminate including compressible material and a cover of sheet material disposed upon at least one face of said compressible material, the combination therewith of improved means for maintaining said cover and material in laminate relation and restraining shifting of said covering relative to the floor, each of said means comprising: a fastening device having a pair of retaining portions disposed at opposite ends of a central portion connecting said retaining portions, said central portion being axially stretchable to a plurality of elongated positions, said central position while in one of said elongated positions passing transversely through said compressible material and cover, said central portion contracting to another of said elongated positions upon compression of said covering adjacent said device, said retaining portions maintaining said central portion in said elongated position, one of said retaining portions being exposed through the bottom face of said covering and having a relatively shallow laterally enlarged end of frictional material contacting the floor, said one retaining portion having a surface beginning at said central portion and extending radially outwards therefrom, all of said surface being in contact with said covering at all times when said device is in said elongated position, the other of said retaining portions also being relatively shallow and laterally enlarged to reduce protrusion of said other retaining portion above said covering.

2. The covering of claim 25 wherein said device comprises an integral elastomeric member having a hollow core through said central portion and said one retaining portion and terminating in a closed end within said other retaining portion, said other retaining portion having a shallow conical shape when said device is at rest, the apex of said other portion forming the outer end thereof and together with said hollow core facilitating insertion of said device in said covering upon elongation of said device by force acting through said hollow core and between said one retaining portion and said closed end of said other retaining portion.

3. The covering of claim 25 wherein at least one of said covers is of flexible sheet material.

4. The covering of claim 25 including a second cover of sheet material, at least some of said devices passing through both of said covers.

5. In a gymnastic mat for use on a floor, said mat including one or more discrete mat sections, each of said sections having a plurality of blocks of compressible, shock absorbing filler material disposed in adjoining lateral relation within a single envelope formed at least in part by a pair of upper and lower flexible sheet covers disposed upon the respective upper and lower faces of said blocks, the combination therewith of improved means fastening at least the lower one of said covers to said blocks to restrain vertical displacement of said blocks relative to each other and slipping of said mat relative to the floor; each of said means comprising: a fastening device having a connecting shank and first and second retaining heads at the respective axial ends of said shank, said shank being resiliently elongatable in an axial direction, said shank and second head passing transversely through at least one of said blocks and said lower cover with said first head engaging the outer face of said lower cover, both of said heads and the length of said shank being effective to maintain said shank in an axially elongated position even upon compression of said filler material in the vicinity of said device, a plurality of said devices being spaced longitudinally of each adjoining pair of said blocks effective to prevent said displacement thereof, said first head being formed of frictional material having a portion thereof disposed to engage the floor, said second head being relatively shallow and laterally enlarged to reduce protrusion of said second head above said upper cover.

6. The mat of claim 29 wherein said device comprises an integral elastomeric member having a hollow core through said shank and first head and terminating in a closed end within said second head, said second head having a shallow conical shape when said device is at rest, the apex of said second head forming the outer end thereof and together with said hollow core facilitating insertion of said device in said mat upon elongation of said device by force acting through said hollow core and between said first head and said closed end of said second head.

7. The mat of claim 29 wherein adjoining pairs of said blocks abut each other in a single vertical plane of abutment, said devices being spaced along and to each side of said abutment.

8. The mat of claim 29 wherein adjoining pairs of said blocks are provided with an overlapping joint therebetween, said devices being spaced along and passing through the overlapping portions of both of each pair of said blocks.

9. The mat of claim 31 wherein at least some of said devices extend through both of said covers, said first and second heads of said some devices engaging the outer faces of said lower and upper covers, respectively.

10. The mat of claim 32 wherein at least some of said devices extend through both of said covers, said first and second heads of said some devices engaging the outer faces of said lower and upper covers, respectively, and sandwiching said blocks therebetween.