Floor Mat

Abstract

A floor mat comprises a multiplicity of substantially rigid elongated rails joined together in closely spaced parallel relation by spaced apart flexible strips that extend transversely across the rails. Each rail has at least two matching slots spaced longitudinally from each other. Each slot is open at the free edge of the rib remote from the base and has an undercut portion spaced from the free edge to leave a projection at the opening of the slot. The connector strips are shaped in cross-section generally to match the shapes of the slots in the rib and extend through the slots. The projections are staked toward the rail bases to engage and secure the connector strips to the rails.

Description

BACKGROUND OF THE INVENTION

This invention relates to floor mats of the type used, for example, in building entrances for dirt removal from the footwear of persons entering the building.

Commonly, almost all types of buildings, including residential, commercial and industrial, employ a grille, grating or mat, either inside or outside (or both) of each entrance to the building, for removal of dirt from the footwear of persons entering the building. A wide variety of gratings and mats are available for this purpose.

Among the attributes that a floor mat should have are effectiveness in dislodging dirt from shoes and other footwear and retaining the dirt dislodged, attractiveness, ease of cleaning, and a durability that permits the grille or mat to withstand environmental conditions, such as abrasions, water, substances present in the dirt carried on the footwear, sunlight and temperature conditions.

SUMMARY OF THE INVENTION

There is provided, in accordance with the invention, a floor mat that very effectively meets the requirements set forth above. In accordance with the invention, a floor mat comprises a multiplicity of substantially rigid, elongated rails disposed generally parallel to each other and in closely spaced relation. Each rail has a base portion that supports a tread surface of the mat and at least one rib, and preferably two, projecting down from the undersurface of the base portion. The rails are connected together to form a mat by at least two connector strips that extend transversely across the rails and are located some distance apart longitudinally of the rails. The ribs of each of the rails have slots that receive the connector strips, the slots being shaped generally to match the cross-section of the connector strip. Each slot is open at the free edge of the rib and has an undercut portion spaced from the free edge that defines a projection on either side of the opening. In a preferred form, the slots are generally T-shaped and the connector strips are correspondingly T-shaped in cross-section. The rails are secured to the connector strips by staking the projections at the slot opening so that they dig slightly into and thereby lock the rails firmly in place at the proper spacing.

In a preferred embodiment of the floor mat, each rail has a rib extending down from the base adjacent each lateral edge, and aligned slots are formed in both ribs. The two spaced-apart ribs strengthen the rail, provide stability for each rail, inasmuch as the rails are supported on the ribs, and enhance the strength of the attachment between the strips and the rails. The connecting strips may extend a short distance below the bottoms of the ribs so that the mat normally rests on the series of connector strips. The bottoms of the connector strips may be roughened or otherwise treated to provide a non-slip surface or may be of an inherently non-slip material, such as a neoprene or some other type of rubber. When the mat is walked upon, there will be a small deflection or displacement of the rails so that the ribs are supported on the floor. The magnitude of projection of the bottoms of the connector strips and the compressibility of the strips are preferably such that when the mat is walked upon, the strips will be compressed so that the ribs, rather than the strips, carry a major part of the load into the floor. In any instance, the degree of projection should be less than that which would permit permanent deformation of the rails.

The tread surface of the mat may be of various materials, including the base material of the rails themselves, e.g., metal or plastic, a grit material applied to the rail base, plastic tread pieces appropriately installed on the rails or a pile fabric (e.g., a carpet) permanently or removably installed on the rail bases. In general, a removable carpet is preferred, inasmuch as carpet is an excellent dirt remover, aesthetically pleasing, and reasonably durable. The form of removable carpet strip and companion rail construction described in U. S. Patent Application Ser. No. 200,372 entitled "Foot Grilles and Mats," filed Nov. 19, 1971, and assigned to the assignee of the present application (also described below and illustrated in some of the figures of the drawings) offers significant advantages in the floor mats of the present invention.

The effectiveness of dirt removal with a floor mat incorporating a carpet as the tread surface is further enhanced by the dirt capturing or storing ability of not only the carpet itself but the inclusion of spaces between the carpet strips afforded in the strip form of construction in the mat; dirt removed on the mat is captured in the spaces in between the rails of the mat and, to some extent, in the spaces under the base portions of the rails. Unlike carpets, molded pieces and other types of continuous mats in which dirt rapidly accumulates to the point that the ability of the tread surface to capture and store additional dirt is virtually eliminated, the dirt capturing and storage capability of a mat, according to the invention, makes it particularly well suited for high traffic areas, such as entrances to stores and commercial and industrial buildings.

The flexibility of the connecting strips of the mats make it possible for the mat to be rolled up, an advantage that is particularly useful in cleaning the dirt storage area below the mat. By rolling the mat away from its usual position on the floor, cleaning of the space that it occupied is conveniently and quickly accomplished. The mat may also be rolled up and stored when it is not required, for example, in good weather.

When constructed of appropriate materials, for example, extruded aluminum rails, highly durable carpet materials, connector strips of neoprene, vinyl or any other durable rubber or plastic, the mat has a very long, useful life, in contrast to the limited useful life of various other types of mats. The use of replaceable carpet strips in the mat further enhance its useful life in a good condition; replacement of the carpet strips restores the mat to "like-new." The mat may be manufactured at relatively low cost, inasmuch as it employs a minimum number of different parts, i.e., a uniform extruded rail, a uniform extruded or molded connector strip, and a uniform tread material. When measured over the useful life of the mat, the effective cost to the user is very low.

The manufacture of the grille is well adapted to mass production techniques. For example, the rails, cut to appropriate lengths, are assembled in a jig, the connector strips are readily pushed into place in the open-ended slots, and an appropriate press with appropriate tooling is employed to stake all of the projections along each connector strip in a single operation.

DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be made to the following description of exemplary embodiments, taken in conjunction with the figures of the accompanying drawings, in which:

FIG. 1 is a plan view of the embodiment;

FIG. 2 is a cross-sectional view of the mat of FIG. 1 taken generally along the lines 2--2 in FIG. 1 and in the direction of the arrows;

FIG. 3 is a view in section of an end threshold member that may be employed with the mat;

FIG. 4 is an end sectional view of a laterally outermost rail of a mat fitted with a longitudinal threshold member;

FIG. 5 is an end cross-sectional view, on a larger scale than in FIGS. 1 and 2, of a typical part of the mat of FIGS. 1 and 2;

FIG. 6 is a bottom view of a typical section of a mat, the view being on a larger scale than FIGS. 1 and 2 and taken generally along view lines 6--6 of FIG. 5;

FIG. 7 is a side sectional view taken generally through a connector strip generally along the lines 7--7 of FIG. 5 and in the direction of the arrows;

FIG. 8 is a cross-sectional view of an alternative embodiment of a connector strip for use in the mat;

FIG. 9 is an end sectional view of the side portion of a mat having an alternative form of longitudinal threshold;

FIGS. 10 and 11 are a top view and an end view, respectively, of a splice between two abutting mat units, FIG. 11 being taken generally along the lines 11--11 of FIG. 10 and in the direction of the arrows;

FIG. 12 is a pictorial view of the end of a mat rail having a carpet strip retainer;

FIG. 13 is a side elevational view of a modified form of rail for use in the mat;

FIG. 14 is an end sectional view of another rail for the mat;

FIG. 15 is a pictorial view of an end portion of a modified form of mat rail in which a group of pins for holding the carpet strip or other tread member are formed integrally in the face of the rail;

FIG. 16 is an end view of one rail of a mat according to the invention having another form of tread member installed in the rail channel; and

FIG. 17 is an end sectional view of a side portion of a mat installed in a preformed and framed recess in a building floor.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring first to FIGS. 1 and 2 of the drawings, an exemplary embodiment of a floor mat, according to the invention, comprises a multiplicity of rails 10 connected together in parallel closely-spaced relation by connector strips 12 to form a unit that is mounted within a peripheral frame 14. Although it is not necessary, it will frequently be desirable for the mat to have a frame or threshold around its perimeter, inasmuch as the tread surface will inevitably be located some distance above a floor on which the mat is used. In commercial installations, the building will often be built with a floor recess at the entrance so that the tread surface of the mat will be at about the same level as the floor. In such a case, the peripheral frame may be a simple rectangular frame having members that are rectangular in cross section. The mat may, alternatively, be mounted within a frame that is mounted directly on the floor of the building, in which case the frame members will preferably be tapered in cross-section (see FIG. 2) to provide an inclined surface ascending from near the floor surface up to approximately the level of the tread surface. Such a threshold form of frame adds to the safety and attractive appearance of the mat.

A threshold frame for the mat may be made of metal or plastic and may be a separate unit or part of the mat. If a separate unit is employed which may, for example, be a frame formed from aluminum extrusions or from a relatively rigid plastic, the frame may be either fastened to the floor or simply laid on the floor.

FIGS. 3 and 4 of the drawings illustrate a form of peripheral frame that is a part of the mat. Inasmuch as it is usually desirable for the mat to be susceptible of being rolled up, the members of the frame, where the frame is part of the mat, are preferably formed of a flexible material, such as rubber or plastic. An exemplary frame 14 (FIGS. 3 and 4) includes end members 16 that are united with the ends of the rails 10 at each end of the mat and side members 17 that are united with the laterally outermost rails. Both the side members and end members 16 and 17 include threshold portions 16a and 17a, respectively, having upper surfaces that taper downwardly from generally the tread surface level of the mat toward the floor. The end members are joined to the ends of the rails by a mechanical connection provided by slots 18 in the ends of the rail (as will be described in more detail below) that receive a longitudinally continuous tab 19 formed on the end threshold or frame member 16. The side members 17 of the frame 14 (FIG. 4) include longitudinally continuous legs 17b that are received under the bases of each of the laterally outermost rails of the mat and are joined to them by an adhesive, rivets, or other appropriate fastener. As mentioned above, a peripheral frame or threshold is an optional, though usually preferred, component of the mat.

Referring to FIGS. 5 to 7, an exemplary embodiment of the mat includes identical parallel substantially rigid rails 10 made of aluminum extrusions cut to appropriate lengths. Each rail 10 is of uniform cross-section along its length and, in cross-section, is generally H-shaped, though the cross of the H is greatly elongated. In cross-section (FIG. 5) the rail is composed of a base portion 22, an upwardly extending flange 24 along each edge of the base, an inwardly projecting lip 26 along the upper end of each flange 24 and a downwardly extending flange or rib 28, also extending along each edge of the base 22. The flanges 24, lips 26 and base 22 define a channel that receives a replaceable carpet strip 30. Reference may be made to U. S. Patent Application Ser. No. 200,372 (referred to above) for a complete description and illustration of appropriate replaceable carpet strips for the mat. Although replaceable carpet strips constitute a preferred form of tread surface for the mat, it will be readily apparent to those skilled in the art that various other forms of tread surface may be used.

The connector strips 12 that join the rails 10 together extend continuously across the mat and extend through aligned slots 32 punched or otherwise formed in both ribs 28 of each rail (see FIG. 7). The slots 32 are generally T-shaped and are open at the lower edge of each rib, the opening being of a substantially lesser dimension longitudinally of each rib than the upper portion (or cross of the T) 33 of the slot. The cross portion 33 of the slot is generally contiguous with the bottom surface of the base portion 22 of the rail. Thus, the configuration of the slot is such as to provide a pair of inwardly extending projections 34 at the lower edge of the rib 28. As originally formed, the projections extend straight along the bottoms of the ribs 28.

The connector strips 12 are made of a flexible material, such as rubber or a flexible plastic. Ninety Durometer neoprene provides excellent results and has the advantage of being more durable under various environmental conditions than are most plastics. Each connector strip 12 is of uniform cross-section along its length and, in cross-section, has a shape substantially matching the original shape of the slots 32 in the ribs, i.e., generally T-shaped in cross-section. The ends of the upper or cross portion 35 of the connector strip 12 are tapered (see FIG. 7), and the base 36 is formed with a continuous lengthwise slot 38. The slot 38 facilitates bending the cross part 35 into a generally U-shape in cross-section and permits the strip 12 to be installed in the aligned slots of the mat rails by bringing the extremities of the top portion of the strip inwardly to clear the inner ends of the projections 34 on the ribs and then pushing the strip into place. The tapered ends at the extremities of the cross part of the strip facilitate acceptance of the end portions of the cross part 35 in the extremities of the slots. The projections 34 on either side of the slots in all ribs of all rails of the mats are staked toward the base into engagement with the strips to anchor the rails in place on the strips. Thus the mat is united into a unit that can be rolled laterally because of the flexibility of the strips 12.

FIG. 8 of the drawings illustrates a modified form of connector strip for the mat. The general cross-sectional shape of the modified form, which is designated by the reference numeral 12a, is the same as the embodiment of FIG. 7. The principal difference between the two forms of strips 12 and 12a is that instead of having a slot extending along the base portion, as in the embodiment of FIG. 7, the embodiment of FIG. 8 is formed of neoprene rubbers of two different hardnesses. The upper or cross part 35a is made of relatively hard, though flexible, neoprene, whereas the bottom or base portion 36a is made of a relatively softer neoprene. In addition, the bottom surface of the base portion 36a is concave, rather than grooved. The softer material in the base portion 36a, permits the connector strip 12a to be bent into a U shape in the manner described above without the groove. The concave shape of the base 36a and the use of a softer rubber in the base portion also enhances the non-slip characteristics provided by the connector strip in the mat; the concavity at the bottom of the base 36a in the embodiment of FIG. 8 is relatively easily compressed under load and in the process forces air out from under the strip to provide a suction-cup effect.

It will be observed in the drawings that the bottom of the connector strips 12 project slightly below the bottom edges of the ribs 28 of the rails. Accordingly, the mat is supported on a floor by the connector strips, and the rubber or other material of the strips provides non-slip characteristics. The extent to which the bottoms of the connector base portions 36 extend below the bottoms of the ribs should not be so great to permit a large flexure or possible permanent deformation of the rails. When the mat is walked upon, the connector strips will deform or displace slightly to allow the ribs to engage and be supported on the floor. It will sometimes be advantageous to roughen or otherwise treat the bottom surfaces of the connector strips to enhance their non-slip properties.

FIG. 9 shows a mat similar to the embodiment of FIGS. 1 and 2 except that the laterally outermost rail 10a has an integral threshold portion 40. The rail 10a is formed of extruded aluminum, though it may be made of plastic or some other metal. The threshold portion 40 has an inclined leg that extends continuously along the length of the laterally outermost rail 10a and has teeth or some other uneven surface to increase its non-slip properties.

FIG. 9 also shows that the connector strips terminate inside of the laterally outermost bottom rib 28 of the rail 10a. For aesthetic reasons, it is usually desirable so to end the connector strip so that the laterally outermost side surfaces of the mat present a clean appearance. The upper portion of the ends of the connector strips may be secured to the underside of the base of the rail by an adhesive, rivets or other appropriate connector. It may be mentioned at this point that an adhesive may be employed to provide further securement of the connector strips 12 to the rails 10 in grilles constructed according to the invention.

A floor mat having an integral threshold (as in FIG. 9) along each lateral edge is particularly well suited for use in corridors or entrance ways to buildings in which the mat runs the entire width from wall to wall. In such an installation, the ends of the rails abut the wall or baseboard so no threshold or frame portion is required at the ends.

An important feature of a mat according to the invention is that it can be rolled up for storage or for cleaning of the space below it. Accordingly, it is desirable not to produce a mat of a size so large as to make it difficult or inconvenient to roll it up. Nonetheless, many installations, such as large entrance ways to commercial and industrial buildings, will utilize very large mats, larger than can conveniently be rolled up. Accordingly, a further feature of the invention, as illustrated in FIGS. 10 and 11 of the drawings, involves providing for butting mat units end to end or side by side, as may be warranted by particular design requirements, so that large areas may be covered but separate convenient-sized units of the mat can be rolled up separately.

FIGS. 10 and 11 illustrate portions of two mat units, designated by the reference numerals 50 and 52, that are placed end to end at a joint 54. The rails of the two units are held in axial alignment with each other and at proper spacing by a splice strip 56. The splice strip, which may be made of metal or plastic, is an elongated member that laps the end portions of the rails of the two mat units 50 and 52 and is formed with upwardly extending ribs 58 having a width equal to the spacing between the sides of the rails and spaced-apart along the length of the strip a distance equal to the pitch distance of the rails. As illustrated in FIGS. 10 and 11, the ribs extend somewhat above the bottoms of the bases of the rails so that the rails nest between the ribs 58 and the bases of the rails rest on the splice strip 56. It should be evident from FIGS. 10 and 11 that the end portions of the ribs 28 along the bottoms of the rails are cut away to an extent sufficient to accommodate the splice strip 56.

FIGS. 10 and 11 should also make readily evident the form of a similar splice strip that can be used to maintain proper spacing and alignment between mat units that are placed side by side. Several splice strips that are substantially the same in general configuration as the splice strip 56 are used at intervals along the lengths of the two laterally abutting units. Each splice strip has three ribs, the outermost two of which are at the end extremities of the splice strips. The center of the three ribs is received at the joint between the two mat units and each of the outermost pair of ribs is received between the laterally outermost pair of rails of the two mat units. The ribs on the underside of the outermost rails of the two units that are laterally abutting are cut away to accept the splice strip. In some installations, it may be desirable to employ metal splice strips that are secured to the floor so that the mat is replaced in its proper position after cleaning. In other instances it may be desirable to employ flexible splice strips and to join the splice strip to one of the two units that abut, using an adhesive, rivets or other appropriate connectors. Splice strips can also be secured to the respective members by forming matching slots and ribs on the splice strip and using the staking principle employed in the basic construction of the mat. For example, referring (briefly) to FIG. 3, a splice strip could be secured to the ends of one of two adjacent mat units by forming slots in the bottom ribs of the rails of the mat to accept a projecting tongue on a splice strip and then staking a projection defined by the slot to anchor the splice strip to the ends of the rails. In FIG. 3, the slot 18 previously described, accepts the continuous tongue 19, and a projection 20 defined by the slot 18 in each rib 28 of each rail is staked to anchor the end frame member 16 to the end of each rail.

The removable carpet strips 30 in a mat of the type of the present invention may be secured to the rails against longitudinal movement by small anchor pieces 60 shown in FIG. 12 that are installed at each end of each rail. Each piece 60 is a thin sheet of metal that has been punched in a manner to create small pointed projections 62 constituted by the metal cut out in the punching operation. The under surface of the piece 60 is coated with a pressure-sensitive adhesive and is adhered to the upper surface of the base of each rail. The projections 62 dig into the base of the carpet strips and retain the carpet strips against longitudinal movement.

FIG. 13 shows an advantageous modification of the rails in which the ribs along one or both sides of each rail are cut away at intervals. As mentioned above, one of the important advantages of a mat according to the invention is the provision of a substantial storage space for dirt dislodged from the footwear of people who tread upon it. The size of the storage space can be further increased by the cut-aways or slots 66 in the ribs, inasmuch as dirt falling between the rails of the mat can readily pass through the slots 66 and into regions directly underneath the rails. The slots 66 should not be of such a length as to materially weaken the rails and permit permanent deformation of the rails in regions between portions 68 of the rails that are left after cutting away to form the slots 66. In other words, a sufficient number of rib portions 68 at a relatively close spacing should be left to support the rails on the floor.

FIG. 14 is exemplary of a modified form of rail for the mat, in this case, a rail 70 formed entirely of plastic and having a toothed or grooved upper surface that provides for dirt removal and enhances the slip resistance properties of the mat. As mentioned previously, various forms of tread surfaces may be employed and FIG. 14 is included to illustrate one of them. Although not illustrated in FIG. 14, all-plastic (or all-rubber) rails may have material of two hardnesses, a soft material as the tread portion and a hard material as the base portion. If the rails 70 are of a thermoplastic material, the connector strip may be united to the rails by heat-staking the projections at either side of the slots. If the connector strips are made of a flexible thermoplastic material, rather than a thermosetting material, the connector strips can readily be glued to the bottoms of the rails, rather than or in addition to being mechanically connected, or they may be ultrasonically or otherwise heat-welded to each other. The ability, according to the invention, to interconnect flexible connector strips with relatively rigid mat rails, even in an all plastic grille, offers advantages over a molded type of mat in that the relatively rigid, spaced-apart, longitudinal rails, coupled with the flexible strips, provides the combined advantages of large dirt storage capability and the capability of being readily rolled up for storage or cleaning. Moreover, extrusion of thermoplastic members for a grille according to the invention will usually provide economical advantages over molding techniques, and the sizes of the units that can be constructed in accordance with the present invention are much greater than those that are conveniently or practically produced by molding.

FIG. 15 illustrates a modified form of retainer arrangement on a rail for holding tread surface elements installed on the rail against longitudinal slipping. A rail 72 substantially identical to the rails 10 of the embodiment illustrated in other figures and described previously is punched with small triagular pins 74 adjacent opposite ends and projecting up from the base 76 of the rail. The pins 74 are constituted by a material punched out of the base portion 76 and, upon installation of a tread element, such as a carpet strip (not shown in the figure), the pins 74 will dig into the bottom of the tread member and hold it against longitudinal movement.

In FIG. 16 of the drawings, another form of tread element 78, namely one extruded from rubber or plastic, is employed in association with a mat that otherwise is identical to the mat illustrated, for example, in FIGS. 5 to 7 of the drawings and described above. Preferably, the plastic or rubber tread elements 78 are of a relatively compressible material and have an upper surface constituted by alternating ribs 80 and slots, the upper ends of the ribs assisting in dirt removal and contributing to the non-slip characteristics of the tread surface and the slots 82 providing dirt storage and, of course, being involved in creating the ribs. The lateral edges of the tread element 78 are formed with longitudinally continuous projecting portions 84 that are received in the side slots of the rail 12. It will usually be desirable to secure the tread elements 78, and similar forms of rubber of plastic tread elements, to the rails 12 by an adhesive, such as a pressure sensitive adhesive. Excellent results have been obtained by applying a strip of double-faced pressure sensitive tape to the rail prior to installing the element 78.

FIG. 17 illustrates the installation of a mat, according to the invention, in a frame 86 built into the building floor 88, in this instance a poured concrete floor. In the illustrated construction, the floor 88 includes a surfacing 90 of stone, terrazzo, or any other appropriate surface material, separated from the frame by a grouting 92. The frame is constituted by continuous extrusions that are generally H-shaped in cross-section, the legs 94 and 96 of the extrusion having inwardly projecting ribs 98 and 100. Masonry anchors 102 having leg portions of appropriate shape are installed at intervals along each member of the frame by clamping the leg 104 on the anchor and an anchor retainer piece 106 together using a screw 108 to produce a firm engagement with the lower ones of the ribs 98 and 100. The horizontal part 110 of the H is located at the elevation of the recessed surface 112 of the concrete floor 88 upon which the mat is supported. The upstanding leg 114 of the extrusion constitutes a peripheral wall within which the mat is fitted within the floor recess.

The mat illustrated in FIG. 17 is identical to the mat illustrated in FIGS. 5 to 7 of the drawings, except that the sides and ends of the mat receive extruded spacers 116 of plastic or rubber that, preferably, are field cut to conform the overall mat size and shape to the field dimensions and shape of the floor recess. The spacers 116 are quite similar to the threshold elements 114 shown in FIGS. 3 and 4 of the drawings and may be installed in a manner identical to the manner in which the threshold elements of FIGS. 3 and 4 are installed on the mat. The upper part of each spacer 116 is formed with longitudinal slots or grooves 118 located, say, one-eighth or one-fourth inch apart, the grooves providing a guideway for field cutting with a knife of the spacers to the desired width for properly fitting the mat. Accordingly, it is desirable initially to make the spacers 116 somewhat wider than the final required dimension; for example, the spacers may have an exposed width extending beyond the sides and ends of the grille rails approximately equal to the width of one rail.

Many other variations and modifications of the invention will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The above described embodiments are, therefore, intended to be merely exemplary, and all such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

Claims

I claim:

1. A floor mat comprising a multiplicity of substantially rigid elongated rails disposed generally parallel to each other in closely spaced relation, each rail having a base portion supporting a tread surface of the mat and at least one rib projecting from the undersurface of the base portion, and at least two flexible compressible connector strips extending transversely of the rails and connecting them together, the rib of each rail having at least two matching slots spaced longitudinally from each other, each slot opening at the free edge of the rib remote from the base and having an undercut portion spaced from the free edge and defining a projection at the free edge of the rib, and the connector strips being shaped in cross-section generally to match the shape of the slots in the ribs and being received in the slots of the rails with a portion thereof projecting slightly below the edge of each rib, each connector strip including a portion extending into the undercut portion of each slot and the projection defined at the free edge of each rib being staked to engage, compress and grip the portion of the connector strip extending into the undercut.

2. A floor mat according to claim 1 wherein each rail has two transversely spaced longitudinally extending ribs, each of which has a free edge spaced from the tread surface an equal distance so that each strip is stably supported on a surface by the spaced ribs.

3. A floor mat according to claim 2 wherein the ribs are located at or close to the opposite lateral edges of the base portions.

4. A floor mat according to claim 1 wherein the connector strips are of uniform cross-section throughout their length.

5. A floor mat according to claim 4 wherein the slots in the ribs are generally T-shaped in cross-section, the cross of the T in each slot defining two undercut portions spaced from the free edge of the rib and defining projections on either side of the slot at the free edge of the rib, the edges of the undercut portions remote from the free edge of the rib being substantially coextensive with the undersurface of the base portion of the rail, and wherein the connector strips are substantially T-shaped in cross-section to match generally the shape of the slots.

6. A floor mat according to claim 1 wherein the portion of each connector strip corresponding to the vertical of the T (hereinafter "vertical portion") is, in cross-section, substantially wider than it is high.

7. A floor mat according to claim 6 wherein the said vertical portion of the connector strip has, in cross-section, a varying height across its width, the height in the region of the center being less than the height adjacent the edges, thereby facilitating bending the strip transversely into generally a U.

8. A floor mat according to claim 7 wherein a zone of the strip corresponding to the crosspiece of a T is of a relatively hard, rigid material and the remainder is of a relatively softer more flexible material.

9. A floor mat according to claim 1 wherein the connector strips are of a moderately compressible material and include a portion normally projecting below the free edge of the rib but compressible substantially to reduce the clearance between the rib edges and a supporting surface.

10. A floor mat according to claim 1 and further comprising a laterally adjacent longitudinally extending threshold portion joined to at least one laterally outermost rail of the mat, the threshold portion having an upper surface sloping laterally downward from generally adjacent the tread surface of the mat toward the surface on which the mat rests.

11. A floor mat according to claim 10 wherein the threshold portion is integral with the said laterally outermost rail.

12. A floor mat according to claim 1 comprising a laterally extending threshold portion joined to the ends of the rails at least at one end of the mat, the laterally extending threshold portion having an upper surface sloping laterally downward from generally adjacent the outer surface of the mat toward the surface on which the mat rests.

13. A floor mat according to claim 1 and further comprising a peripheral frame having end members abutting the respective ends of the rails and side members abutting the laterally outermost rails of the mat.

14. A floor mat according to claim 13 wherein the end members and side members of the frame have upper surfaces sloping laterally downward from generally adjacent the tread surface of the mat toward the surface on which the mat rests.

15. A floor mat according to claim 14 wherein the end members and side members of the frame are secured to portions of the rails that they abut.

16. A floor mat comprising two separate floor mat units, each of said units including a multiplicity of substantially rigid elongated rails disposed generally parallel to each other in closely spaced relation, each rail having a base portion supporting a tread surface of the mat and at least one rib projecting from the undersurface of the base portion, and at least two flexible connector strips extending transversely of the rails and connecting them together, the rib of each rail having at least two matching slots spaced longitudinally from each other, each slot opening at the free edge of the rib remote from the base and having an undercut portion spaced from the free edge, and the connector strips being shaped in cross-section generally to match the shape of the slots in the ribs, the units abutting each other with their rails aligned end to end, and means for retaining the ends of the rails of the respective mat units in axial alignment with each other against relative lateral displacement.

17. A floor mat according to claim 16 wherein said retaining means includes an elongated splice strip lapping end portions of the rails of the respective units and having transverse ribs dimensioned and spaced for coaction with the cross-sectional shapes of the rails.

18. A floor mat comprising two separate mat units, each of said units having a multiplicity of substantially rigid elongated rails disposed generally parallel to each other in closely spaced relation, each rail having a base portion supporting a tread surface of the mat and at least one rib projecting from the under-surface of the base portion, and at least two flexible connector strips extending transversely of the rails and connecting them together, the rib of each rail having at least two matching slots spaced longitudinally from each other, each slot opening at the free edge of the rib remote from the base and having an undercut portion spaced from the free edge, and the connector strips being shaped in cross-section generally to match the shape of the slots in the ribs, the units abutting each other laterally with a laterally outermost rail of one unit disposed adjacent a laterally outermost rail of the other unit in closely spaced parallel relation, and means for retaining said laterally outermost rails in parallel, closely-spaced relation against relative lateral displacement.

19. A floor mat according to claim 18 wherein said retaining means includes at least one splice strip lapping the respective laterally outermost adjacent rails of the two units and having ribs dimensioned and spaced for coaction with the cross-sectional shapes of the rails substantially to preclude relative lateral movement of said laterally outermost rails.

20. A floor mat according to claim 1 wherein the rails are of uniform cross-section along their length, each rail including in cross-section a base portion having an essentially flat, shallow channel defined by a flange portion along each side of and extending upwardly from the base portion and a lip portion extending inwardly from the upper edge of each flange portion and defining with each flange portion an inwardly open slot extending along each side of the base portion, and further comprising an elongated strip of pile fabric material removably received in the flat, shallow channel and anchor members on the base portion of each rail adjacent opposite ends thereof and including teeth penetrating into the overlying pile fabric material and securing the pile fabric material against longitudinal movement in the channel.