Sectional Flooring with Coupling Member, and Assembling Method Thereof

Abstract

Sectional flooring is provided. The sectional flooring includes first, second, and third floor boards (10,20 and 30) and a coupling member (40) for connecting the first and second floor boards (10 and 20) that are arranged to be adjacent to each other in a longitudinal direction. The coupling member (40) includes a base portion (41) placed over-adjacent first and second floor boards (10 and 20), a pair of side hooks (42) protruding from opposite ends of the base portion (41) toward top surfaces of the first and second floor boards (10 and 20), and a pair of cantilever hooks (43) spaced apart from each other by a predetermined distance and protruding from a center of the base portion (41). Each of the cantilever hooks (43) includes a hook step (431). The hook step (431) includes an upper portion formed with an inclined surface inclined at a predetermined lead angle (OL) and a lower portion is formed with an inclined surface inclined at a predetermined return angle (OR).

Description

TECHNICAL FIELD

The present invention relates to sectional flooring. More particularly, the present invention relates to sectional flooring with a plurality of floor boards that can be securely coupled to each other by an elastic coupling member, and a method of assembling the same.

2. BACKGROUND ART

Generally, sectional flooring is formed with a plurality of floor boards each having a predetermined dimension, which are made separately, and assembled together on the floor of a building. In the conventional sectional flooring, each of the floor boards is formed in a rectangular shape having a pair of longitudinal sides and a pair of lateral sides. Each of the floor boards is provided at longitudinal or lateral sides with a coupling structure by which the floor board can be coupled to another floor board.

That is, the coupling structure includes at least one protrusion and at least one recess. Therefore, the two adjacent floor boards are assembled with each other by the coupling structure formed with the protrusion and the recess and fixed to the floor of the building using an adhesive applied to a bottom of the floor boards. However, such a fixing technique has disadvantages in that it is difficult to remove the floor boards from the floor of the building, and an epoxy-based adhesive that is harmful to the human body should be used.

It has been proposed that the adhesive be further applied to the sides of the floor boards with the protrusions and grooves to simultaneously utilize the mechanical assembling force between the protrusions and the grooves and the adhesion force of the adhesive in assembling two adjacent floor boards. This assembling structure is generally called a suspension-type structure and involves advantages in that the floor boards can be easily installed and removed from the floor of the building. However, in case the adhesive is frozen or used after long-term storage, the adhesion force of the adhesive is deteriorated. Further, when the adhesive is not properly applied to the floor boards, a gap or a stepped difference may be formed between the floor boards.

DISCLOSURE OF INVENTION

Technical Problem

Therefore, as a modified structure of the suspension-type structure, a structure where the two adjacent floor boards are assembled together by a locking member instead of the adhesive has been recently proposed. With regard to this structure, each of U.S. Pat. No. 4,426,820 and Japanese Laid-Open Patent No. H3-169967 discloses a sectional flooring having a locking member provided on a side of a floor board.

However, in this modified structure using the locking member, the floor boards that are generally wood panels, medium density fiberboard, or high density fiberboard may contract because of floor heating due to a material property thereof. The contraction of the floor boards deteriorates the coupling force of the locking member, resulting in a gap between the floor boards.

Furthermore, the wood panels, medium density fiberboard, and high density fiberboard have lower elasticity as compared with floor boards that are formed of synthetic resin. Therefore, when the floor boards are assembled together through a snap-in method, a portion of the locking member on which the force is concentrated may be easily damaged.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

Technical Solution

The present invention has been made in an effort to provide sectional flooring that can prevent a gap or stepped difference from occurring between floor boards by enhancing a coupling force between the floor boards even when the floor boards contract because of the floor heating, and an assembling method thereof.

The present invention also provides sectional flooring that can improve the endurance of floor boards by preventing a coupling portion between the floor boards from being damaged.

In an exemplary embodiment of the present invention, a sectional flooring includes first, second, and third floor boards each having a core formed of wood, the floor boards being provided at longitudinal and lateral sides with coupling structures and assembled together, and a coupling member for connecting the first and second floor boards that are arranged to be adjacent to each other in a longitudinal direction thereof, the coupling member being coupled to lower portions of the lateral sides of the first and second floor boards. The coupling member includes a base portion placed over the adjacent first and second floor boards; a pair of side hooks protruding from opposite ends of the base portion toward top surfaces of the first and second floor boards, the side hooks being fitted in the lateral sides of the first and second floor boards to endure a stress applied in a longitudinal direction of the first and second floor boards; and a pair of cantilever hooks spaced apart from each other by a predetermined distance and protruding from a center of the base portion toward the top surfaces of the first and second floor boards, each of the cantilever hooks including a hook step engaged with the lateral side of the corresponding one of the first and second floor boards and an inclined portion extending downward from the hook step, the cantilever hooks supporting a stress applied in a thickness direction of the floor boards. Each of the hook steps includes an upper portion formed with a surface inclined at a predetermined lead angle θ_L with respect to a vertical line extending in the thickness direction of the first and second floor boards, and a lower portion formed with a surface inclined at a predetermined return angle θ_R with respect to a horizontal line extending in a length direction of the first and second floor boards.

The lead angle θ_L may be 5°-45° and the return angle θ_R may be equal to or less than 60°.

Each of the first and second floor board may include a first recess portion for receiving the side hook, the first recess portion being formed on a lower portion of the lateral side, which faces the coupling member; a coupling protrusion protruding from a side of the first recess portion toward the lower portion thereof and fitted between the side hook and the cantilever hook; a second recess portion that is provided on a side of the coupling protrusion, which faces an outer side of the floor board, to receive the hook step of the cantilever hook; and a projection for guiding a motion of the cantilever hook, the projection being formed with an inclined portion on a lower portion of the second recess portion.

A cavity for receiving thermal expansion of the coupling member may be formed between the first and second floor boards and a coupling surface of the coupling member. Particularly, a width “a” of the cavity between the coupling member and the first and second floor boards at a top surface of the base portion of the coupling member and the cantilever hook is 0.05˜0.20 mm, and a width “b” of the cavity between the coupling member and the first and second floor boards at an outer surface of the side hook is 0.05-0.50 mm.

An upper portion of the lateral side of each of the first and second floor boards, which does not face the coupling member, may be formed with a vertical surface, and the vertical surfaces of the first and second floor boards may contact each other.

The first floor boards may be provided at a longitudinal side with an upper hook step protruding toward the third floor board, an intermediate hook step protruding from a bottom of the upper hook step toward a bottom surface thereof, and a fourth recess portion provided at a side of the intermediate hook step, which faces an inner portion thereof, and the third floor boards is provided at the longitudinal side with a fifth recess portion for receiving the upper hook step, a sixth recess portion for receiving the intermediate hook step, and a lower hook step that extends from the sixth recess portion to an external portion thereof and is received in the fourth recess portion.

In another exemplary embodiment of the present invention, a method of assembling the sectional flooring includes assembling the floor board with the coupling member, interconnecting the longitudinal sides of the first and third floor boards by rotating the first floor board downward after fitting the upper hook step of the first floor board into the fifth recess portion of the third floor board, and interconnecting the lateral sides of the first and second floor boards by assembling the first floor board with the coupling member by pressing the first floor board downward.

ADVANTAGEOUS EFFECTS

According to the present invention, since the lateral sides of the floor boards are coupled to each other by the coupling member having the above-described structure and material property, the coupling force between the flooring boards can be enhanced and thus the gap and step difference between the floor boards can be suppressed even when the floor boards can contract because of floor heating. Furthermore, since no damage such as a crack occurs on the coupling portion during the assembling process of the sectional flooring, the endurance of the section flooring can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial top view of a sectional flooring according to a first exemplary embodiment of the present invention.

FIG. 2 is a sectional view taken along line I-I of FIG. 1.

FIG. 3 is an exploded sectional view of FIG. 2.

FIG. 4 is an enlarged view of a coupling member depicted in FIG. 3.

FIG. 5 is a sectional view taken along line II-II of FIG. 1.

FIG. 6 is a partial sectional view of the sectional flooring of FIG. 1, illustrating an assembling process of longitudinal sides of floor boards.

FIG. 7 is a partial sectional view of the sectional flooring of FIG. 1, illustrating an assembling process of lateral sides of floor boards.

FIG. 8 is a partial sectional view of a sectional flooring according to a second exemplary embodiment of the present invention.

FIG. 9 is a partial sectional view of a sectional flooring according to a third exemplary embodiment of the present invention.

FIG. 10 is a partial sectional view of a sectional flooring according to a fourth exemplary embodiment of the present invention.

FIG. 11 is a partial sectional view of a sectional flooring according to a fifth exemplary embodiment of the present invention.

MODE FOR THE INVENTION

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

FIG. 1 is a partial top plan view of sectional flooring according to a first exemplary embodiment of the present invention.

Referring to FIG. 1, sectional flooring 500 according to an exemplary embodiment of the present invention includes a plurality of floor boards 10, 20, and 30 each having a pair of longitudinal sides 2 and a pair of lateral sides 4, and a plurality of coupling members 40. The longitudinal and lateral sides 2 and 4 are provided with coupling structures. The coupling members 40 are provided between the lateral sides 4 of the floor boards 20, 30, and 30 to interconnect the floor boards 10, 20, and 30, which are arranged in a longitudinal direction (a y-direction in FIG. 1), by associating with the coupling structures formed on the lateral sides 4 of the floor boards 10, 20, and 30.

Each of the floor boards 10, 20, and 30 has a core formed of wood. Each of the floor boards 10, 20, and 30 is a rectangular panel having a predetermined thickness and area The floor boards 10, 20, and 30 may be wood panels, medium density fiberboard (MDF), or high density fiberboard (HDF). The floor boards 10, 20, and 30 may be coated with a pre-impregnated foil or paint.

The coupling members 40 may be formed of a material that is similar to the floor boards 10, 20, and 30 or a material having elasticity greater than the floor boards 10, 20, and 30. The coupling members 40 are provided on the lateral sides of the floor boards 10, 20, and 30. Therefore, the two floor boards 10 and 20 that are arranged lengthwise (the y-direction in FIG. 1) are interconnected at their lateral sides 4 by the coupling member 40.

The coupling structure provided on the lateral sides of the first and second floor boards 10 and 20 will be described with reference to FIGS. 2, 3, and 4, and the coupling structure provided on longitudinal sides of the first and third floor boards 10 and 30 will be described.

FIG. 2 is a sectional view taken along line I-I of FIG. 1, and FIG. 3 is an exploded sectional view of FIG. 2. FIG. 4 is an enlarged view of a coupling member depicted in FIG. 3.

Referring to FIG. 2 through FIG. 4, the coupling member 40 includes a base portion 41 having a predetermined width and a predetermined thickness, a pair of side hooks 42 protruding from opposite ends of the base portion 41 toward top surfaces of the first and second floor boards 10 and 20, and a pair of cantilever hooks 43 spaced apart from each other by a predetermined distance and protruding from a center of the base portion 41 toward the top surfaces of the first and second floor boards 10 and 20.

A height H₂ (see FIG. 3) of each of the cantilever hooks 43, which is measured based on the top surface of the base portion 41, is greater than a height H₃ (see FIG. 3) of each of the side hooks 42. The pair of side hooks 42 and the pair of cantilever hooks 43 are symmetrically arranged with respect to an imaginary vertical line (broken line in FIG. 3) passing through the center of the coupling member 40.

The bottom surface of the base portion 41 is located on the same horizontal plane as the bottom surfaces of the first and second floor boards 10 when they are installed on the floor. An overall height H_T (see FIG. 2) of the coupling member 40 is less than a thickness T (see FIG. 2) of each of the first and second floor boards 10 and 20, so that the coupling member 40 is not shown when viewed from the top of the sectional flooring.

The side hooks 42 may be perpendicular to the base portion 41 or inclined toward the cantilever hooks 43 at a predetermined angle. The side hooks 42 resist against stress (mostly tension) applied in a length direction (the y-direction in FIG. 4) of the first and second floor boards 10 and 20.

The cantilever hooks 43 are provided at an upper portion thereof with hook steps 431. A width of a portion of each of the cantilever hooks 43 between the base portion 41 and the hook step 431 is gradually reduced as it goes away from the base portion 41. In a sectional view of the cantilever hooks 43, inner surfaces of the cantilever hooks 43, which face the central line, are straight, and outer surfaces of the cantilever hooks 43, which face the side hooks 42, are defined by inclined portions 432.

A space defined between the cantilever hooks 43 provides a marginal space required when the cantilever hooks 43 are biased toward the center of the coupling member 40 during the coupling of the coupling member 40 to the floor boards 10 and 20.

An upper portion of each of the hook steps 431 is formed with a surface that is inclined at a predetermined lead angle θ_L (see FIG. 4) with respect to a vertical line extending in a thickness direction (a z-direction in FIGS. 2 through 4) of the floor boards 10 and 20, and a lower portion of each of the hook steps 431 is formed with a surface that is inclined at a predetermined return angle θ_R (see FIG. 4) with respect to a horizontal line extending in a length direction (a x-direction in FIGS. 2 through 4) of the floor boards 10 and 20.

The upper portion of the hook step 431, on which the lead angle θ_L is defined, functions to guide a motion of the cantilever hook 43 such that the cantilever hook 43 is biased toward the center of the coupling member 40 rather than toward the side hook 42 when a force for pressing the hook stop 431 downward and outward of the coupling member 40 is applied by the floor boards 10 and 20 during the assembly of the floor boards 10 and 20 with the coupling members 40.

The cantilever hooks 43 are rocked and coupled to the coupling structure provided on the first and second floor boards 10 and 20 to securely interconnect the floor boards 10 and 20. In addition, the cantilever hooks 43 resist against the stress applied in the thickness direction (the z-direction in FIGS. 2 through 4) of the floor boards 10 and 20 to prevent the floor boards 10 and 20 from being spaced apart from each other and a step difference from occurring between the floor boards 10 and 20. A maximum width H_O(see FIG. 3) may be less than a width W (see FIG. 3) of the side hook 42.

The first and second floor boards 10 and 20 are provided at lower portions of the lateral sides thereof, which face the coupling member 40, with first recess portions 11 and 21 receiving the side hooks 42, and at sides of the first recess portions 11 and 21, which face outer sides of the floor boards 10 and 20, with coupling protrusions 12 and 22 fitted between the side hooks 42 and the cantilever hooks 43.

At this point, projections 14 and 24 corresponding to the inclined portions 432 of the cantilever hooks 43 are formed on sides of the coupling protrusions 12 and 22, on which second recess portions 12 and 23 are formed. That is, surfaces of the projections 14 and 24, which face the coupling member 40, are inclined to correspond to the inclined portions 432. The inclined surfaces of the projections 14 and 24 together with the hook steps 431 of the cantilever hooks 43 function to guide a motion of the cantilever hooks 43 such that the cantilever hooks 43 are biased toward the center of the coupling member 40 when the coupling member 40 is assembled with the floor boards 10 and 20.

A stopper projection 15 is formed on an upper portion of the lateral side of one (the first floor board 10 in this exemplary embodiment) of the first and second floor boards 10 and 20. A third recess portion 25 for receiving the stopper projection 15 is formed on an upper portion of the lateral side of the other (the second floor board 20 in this exemplary embodiment) of the first and second floor boards 10 and 20. The stopper projection 15 and the third recess portion 25 function as a stopper during the assembly of the coupling member with the first and second floor boards 10 and 20.

The stopper function allows the coupling member 40 to be effectively assembled with the floor boards 10 and 20 when the floor boards are installed on a floor having an uneven surface or on a soft material such as Styrofoam.

FIG. 5 is a sectional view taken along line I-III of FIG. 1.

Referring to FIG. 5, the first floor board 10 is provided at a longitudinal side with an upper hook step 16 protruding toward the third floor board 30. An intermediate hook step 17 protrudes from a bottom of the upper hook step 16 toward the first floor board 10, and a fourth recess portion 18 is provided at a side of the intermediate hook step 17, which faces an inner portion of the first floor board 10.

The third floor board 30 is provided at the longitudinal side with a fifth recess portion 31 for receiving the upper hook step 16 of the first floor board 10, a sixth recess portion for receiving the intermediate hook step 17 of the first floor board 10, and a lower hook step 33 that extends from the sixth recess portion 32 to an external portion of the third floor board 30 and is received in the fourth recess portion 18 of the first floor board 10.

The following will describe an assembling process of the sectional flooring with reference to FIGS. 6 and 7.

FIG. 6 is a partial sectional view of the sectional flooring of FIG. 1, illustrating an assembling process of the longitudinal sides of floor boards, and FIG. 7 is a partial sectional view of the sectional flooring of FIG. 1, illustrating an assembling process of lateral sides of floor boards.

Referring first to FIG. 6, the upper hook step 16 of the first floor board 10 is first fitted into the fifth recess portion 31 of the third floor board 30 at a predetermined angle, and subsequently the first floor board 10 rotates downward. Then, the upper and intermediate hook steps 16 and 17 of the first floor board 10 are respectively fitted in the fifth and sixth recess portions 31 and 32, thereby completing the assembling of the first and third floor boards 10 and 30.

Here, when the first floor board 10 rotates downward, the first floor board 10 is placed on the coupling member 40 engaged with the second floor board 20. In this state, when the first floor board 10 is pressed downward, the first floor board 10 is engaged with the coupling member 40 in a snap-in manner and is thus assembled with the second floor board 20.

Referring to FIG. 7, as the first floor board 10 moves downward, the inclined upper portion of the hook step 431 of the cantilever hook 43 contacts and slides over the inclined projection 14 of the first floor board 10 and thus the cantilever hook 43 of the coupling member 40 can be easily biased toward the center of the coupling member 40. Subsequently, as the first floor board 10 further moves, the cantilever hook 43 is restored such that the hook step 431 of the cantilever hook 43 is fully engaged with the second recess portion 13 of the first floor board 10.

After the above, the side hook 42 of the coupling member 40 is fitted in the first recess portion 11 of the first floor board 10 and the coupling protrusion 12 of the first floor board 10 is fitted between the side hook 42 and the cantilever hook 43, thereby securely assembling the coupling member 40 with the first floor board 10. At this point, a width P of the coupling protrusion 12 may be 3.0 mm or more so that the coupling protrusion 12 is not damaged by stress generated by the contraction of the floor boards.

Further, the lead angle θ_L (see FIG. 4) of the hook step 431 of the cantilever hook 43 may range from 5° to 45°. When the lead angle θ_L is less than 5 or greater than 45°, the guide effect obtained by the sliding over the projection 14 of the first floor board 10 is deteriorated. Therefore, it becomes difficult to effective guide the movement of the cantilever hook 43. The return angle θ_R (see FIG. 4) may be set to be 60° or less considering a frictional coefficient of a contact surface between the coupling protrusion 12 and the coupling member 40.

The inclined portion 432 formed below the hook step 431 allows the cantilever hook 43 to be effective biased when the coupling member is engaged with the floor board. At this point, a ratio between a lower end width H_O (see FIG. 4) of the cantilever hook 43 facing the hook step 431 and a lower end width H_L (see FIG. 4) of the hook step 431 may be 2:1 so that the biasing of the cantilever hook 43 can be more effectively realized.

As described above, in the sectional flooring 500 according to this exemplary embodiment of the present invention, the floor boards are assembled together through an insertion-and-rotation manner at the longitudinal sides and through a snap-in manner at the lateral sides by using the coupling member 40. Therefore, the installation of the sectional flooring 500 can be effectively performed with less ambient interference.

With the above-described structure, the coupling member 40 may be formed of a material having a modulus of elasticity of 1-4 GPa. The coupling member 40 may have a modulus of elasticity that is similar to that of the high density fiberboard and the medium density fiberboard. When the modulus of elasticity of the coupling member is less than 1 GPa, the coupling member cannot resist against the stress generated when the floor boards are contracted by the floor heating, and is easily bent. Therefore, the coupling force at the coupling portion is deteriorated.

The coupling member 40 may be manufactured through an extrusion molding process or an injection molding process. Specifically, a molding process that can manufacture the coupling members 40 within an error range of 0-0.05 mm.

FIG. 8 is a partial sectional view of sectional flooring according to a second exemplary embodiment of the present invention.

Referring to FIG. 8, sectional flooring 501 of the present exemplary embodiment is the same as the sectional flooring of the first exemplary embodiment except that cavities for absorbing thermal expansion of the flooring boards 102 and 201 and the coupling member 40 are formed between coupling surfaces of a first floor board 101 and a coupling member 40 and between a second floor board 201 and the coupling member 40.

The cavities 50 function to absorb a repulsive force caused by interference of cantilever hooks 43 and reduce a gap that is formed between the floor boards 101 and 201 by thermal expansion of the coupling member 40 in the event of the floor heating in a state where the coupling member 40 is assembled with the floor boards 101 and 201. The cavities 50 further function to reduce frictional force between the coupling member 40 and the floor boards 101 and 201 to thereby improve the work efficiency when the coupling member 40 is assembled with the floor boards 101 and 201.

Considering the floor heating and the material of the coupling member 40 and the floor boards 101 and 201, a width a of the cavities between the coupling member 40 and the floor boards 101 and 201 at a top surface of a base portion 41 of the coupling member 40 and the cantilever hook 43 may be 0.05-0.20 mm, and a width b of the cavities between the coupling member 40 and the floor boards 101 and 201 at outer surfaces of the side hooks 42 may be 0.05-0.50 mm.

FIG. 9 is a partial sectional view of a sectional flooring according to a third exemplary embodiment of the present invention.

Referring to FIG. 9, sectional flooring 502 of the present exemplary embodiment is the same as the sectional flooring of the first exemplary embodiment except that an upper portion of a lateral side of each of first and second floor boards 102 and 202, which does not face a coupling member 40, is formed with a vertical surface. With this structure, the upper portion of the lateral side of the first floor board 102 contacts the upper portion of the lateral side of the second floor board 202 without any stopper function.

FIG. 10 is a partial sectional view of a sectional flooring according to a fourth exemplary embodiment of the present invention.

Referring to FIG. 10, sectional flooring 502 of the present exemplary embodiment is the same as the sectional flooring of the first exemplary embodiment except that a locking structure formed with a projection 19 and a groove 26 is provided on upper portions of lateral sides of first and second floor boards 103 and 203, which do not face a coupling member 40.

That is, the first floor board 103 is provided with the projection 19 protruding toward the second floor board 203 and the second floor board 203 is provided with a groove 26 for receiving the projection 19. Accordingly, when the first floor board 103 is fitted into the coupling member 40 by being pressed downward, the projection 19 is engaged with the groove 26, thereby effectively preventing the movement of the floor boards 103 and 203 in a thickness direction (the z-direction in FIG. 10).

FIG. 11 is a partial sectional view of a sectional flooring according to a fifth exemplary embodiment of the present invention.

Referring to FIG. 11, sectional flooring 502 of the present exemplary embodiment is the same as the sectional flooring of the first exemplary embodiment except that glue pockets 51 are formed on bottom surfaces, which face a base portion 41 of a coupling member 40, of coupling protrusions 12 and 22 of respective first and second floor boards 104 and 204.

Therefore, when the first floor board 104 is connected to the second floor board 204 after an adhesive is applied to a top surface of the base portion 41 of the coupling member 40, excess adhesive is confined in the glue pockets 51 and thus a step difference between the floor boards 104 and 204, which is caused by the adhesive, can be prevented. According to this exemplary embodiment, the coupling force by the adhesive and the mechanical coupling force by the coupling member can be simultaneously realized.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. Sectional flooring comprising:

first, second, and third floor boards each having a core formed of wood, the floor boards being provided at longitudinal and lateral sides with coupling structures and assembled together; and

a coupling member for connecting the first and second floor boards that are arranged to be adjacent to each other in a longitudinal direction thereof, the coupling member being coupled to lower portions of the lateral sides of the first and second floor boards, wherein the coupling member 40 comprises

a base portion placed over the adjacent first and second floor boards;

a pair of side hooks protruding from opposite ends of the base portion toward top surfaces of the first and second floor boards, the side hooks being fitted in the lateral sides the first and second floor boards to endure a stress applied in a longitudinal direction of the first and second floor boards; and

a pair of cantilever hooks spaced apart from each other by a predetermined distance and protruding from a center of the base portion toward the top surfaces of the first and second floor boards, each of the cantilever hooks including a hook step engaged with the lateral side of the corresponding one of the first and second floor boards and an inclined portion extending downward from the hook step, the cantilever hooks supporting a stress applied in a thickness direction of the first and second floor boards,

wherein each of the hook steps includes an upper portion formed with a surface that is inclined at a predetermined lead angle θL with respect to a vertical line extending in the thickness direction of the first and second floor boards, and a lower portion formed with a surface that is inclined at a predetermined return angle θR with respect to a horizontal line extending in a length direction of the first and second floor boards.

2. The sectional flooring of claim 1, wherein the lead angle θL is 5°˜45° and the return angle θR is equal to or less than 60°.

3. The sectional flooring of claim 1, wherein the hook steps and the inclined portions are provided on outer surfaces of the cantilever hooks, which face the side hooks, and a width of each of the inclined portion is gradually reduced as it goes away from the base portion.

4. The sectional flooring of claim 3, wherein a ratio between a lower end width H of the cantilever hook facing the hook step and a lower end width HL of the hook step is about 2:1.

5. The sectional flooring of claim 1, wherein the first and second floor board includes:

a first recess portion for receiving the side hook, the first recess portion being formed on a lower portion of the lateral side that faces the coupling member; a coupling protrusion, protruding from a side of the first recess portion toward the lower portion of the first and second floor board and fitted between the side hook and the cantilever hook;

a second recess portion, that is provided on a side of the coupling protrusion that faces an outer side of the first and second floor board, to receive the hook step of the cantilever hook; and

a projection for guiding a motion of the cantilever hook, the projection being formed with an inclined portion on a lower portion of the second recess portion.

6. The sectional flooring of claim 5, wherein the coupling protrusion has a width equal to or greater than 3.0 mm in a longitudinal direction of the first and second floor board.

7. The sectional flooring of claim 5, wherein a cavity for receiving thermal expansion of the coupling member is formed between the first and second floor board and a coupling surface of the coupling member.

8. The sectional flooring of claim 7, wherein a width “a” of the cavity between the coupling member and the first and second flooring board at a top surface of the base portion of the coupling member and the cantilever hook is 0.05-0.2 mm, and a width “b” of the cavity between the coupling member and the first and second floor board at an outer surface of the side hook is 0.05-0.5 mm.

9. The sectional flooring of claim 5, wherein an upper portion of the lateral side of the first and second floor board that does not face the coupling member is formed with a vertical surface, and the vertical surfaces of the first and second floor boards and contact each other.

10. The sectional flooring of claim 5, wherein a stopper projection is formed on an upper portion, which does not face the coupling member of the lateral side of one of the first and second floor boards, and a third recess portion for receiving the stopper projection is formed on an upper portion, which does not face the coupling member, of the lateral side of the other of the first and second floor boards.

11. The sectional flooring of claim 5, wherein a protrusion is formed on an upper portion, which does not face the coupling member, of the lateral side of one of the first and second floor boards, and a groove is formed on an upper portion, which does not face the coupling member, of the lateral side of the other of the first and second floor boards.

12. The sectional flooring of claim 5, wherein a glue pocket is formed on a bottom of the coupling protrusion that faces the base portion of the coupling members.

13. The sectional flooring of claim 5, wherein:

the first floor board is provided at a longitudinal side a with an upper hook step protruding toward the third floor board, an intermediate hook step protruding from a bottom of the upper hook step toward a bottom surface thereof, and a fourth recess portion provided at a side of the intermediate hook step, which faces an inner portion thereof; and

the third floor boards is provided at the longitudinal side with a fifth recess portion for receiving the upper hook step, a sixth recess portion for receiving the intermediate hook step, and a lower hook step that extends from the sixth recess portion to an external portion thereof and is received in the fourth recess portion.

14. The sectional flooring of claim 1, wherein the floor boards are formed of wood panels, high density fiberboard, or medium density fiberboard.

15. The sectional flooring of claim 1, wherein the coupling member is formed of a material having a modulus of elasticity of 1˜4 GPa.

16. A method of assembling the sectional flooring claimed in claim 13, comprising:

assembling the second floor board with the coupling member;

interconnecting the longitudinal sides a of the first and third floor boards by rotating the first floor board downward after fitting the upper hook step of the first floor board into the fifth recess portion of the third floor board; and

interconnecting the lateral sides of the first and second floor boards by assembling the first floor board with the coupling member by pressing the first floor board downward.

17. The method of claim 16, wherein when the first floor board is assembled with the coupling member, the projection biases the cantilever hook toward a center of the coupling member as the projection of the first floor board contacts and slides.