# Patent

## Title
Floor panel

## Abstract

In a floor panel provided with upper and lower members which have concave spaces and side surfaces having heights and are formed as a box shape, and structured such that the upper and lower members are combined up and down so as to communicate the respective concave spaces so as to form an internal space in an inner portion, the floor panel has a joint portion in which height leading end portions of the side surfaces of the upper and lower members are folded so as to enwrap each other so as to be connected, and the joint portion is arranged in a height midstream portion of the side surface of the floor panel, and is arranged at a position which is retreated to an inner side of the floor panel in relation to the side surface in both height end sides of the floor panel.

## Background
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a floor panel which is used in a free access floor.
Description of the Conventional Art
The floor panel according to the present invention is used in the free access floor. The floor panel of the free access floor is provided above a foundation floor surface which is formed by a concrete material and constructs a part of a building construction, so as to be spaced (refer, for example, to patent document 1).
FIGS. 8 to 11 are views which are referred for describing a conventional floor panel 2. The conventional floor panel 2 constructs a free access floor 1 together with a support leg 4 which is provided in a rising manner on a foundation floor surface 3, as shown in FIG. 8.
The floor panel 2 is arranged on a horizontal surface having a height spaced above from the foundation floor surface 3 so as to be adjacent to each other in both vertical and horizontal axial directions as seen from the above, and four corner portions of the floor panel 2 are detachably supported to the support legs 4 which are provided in a rising manner on the foundation floor surface 3.
The floor panel 2 is constructed as shown by FIGS. 9 and 11, by mainly combining a top plate 6 formed approximately as a tabular shape so that an upper surface 6c is formed approximately as a square shape, and a bottom plate 8 formed as a box shape having a bottom surface 8c which is approximately formed as a square shape in the same manner as the upper surface 6c and having a depth, vertically so that a top plate portion 6a and a bottom plate portion 8a are opposed to each other, as shown in FIG. 10. The top plate 6 and the bottom plate 8 are both constructed by using a steel plate member.
In the bottom plate 8 of the floor panel 2, as shown in FIG. 11, there is formed a side plate portion 8b obtained by folding the bottom plate portion 8a approximately vertically from a peripheral edge portion toward an upper side in the drawing, and a peripheral edge portion 8f folded approximately vertically toward a right side in the drawing is formed in an upper end portion of the side plate portion 8b. As a result, the bottom plate 8 is formed as a box shape having a concave space 8d which is formed in an inner side in a horizontal direction of the side plate portion 8b. 
Further, since a U-shaped portion 6b folded like a U-shaped form so as to enwrap the peripheral edge portion 8f of the bottom plate 8 is formed in the peripheral edge portion 6f of the top plate 6, the peripheral edge portion 6f of the top plate 6 is connected to the peripheral edge portion 8f of the bottom plate 8.
As mentioned above, the floor panel 2 is formed as a hollow shape having an internal space 10 by integrally connecting the top plate 6 and the bottom plate 8. Further, the internal space 10 is provided with a reinforcing member 12 having a thickness.
However, since the bottom plate 8 is obtained by a deep drawing process of a plate-like member while using a pressing machine, such a tension force that the bottom plate 8 is extended in a depth direction (a vertical direction in FIG. 11) is applied. Therefore, there is a problem that a crack or a breaking may be easily generated in the side plate portion 8b of the bottom plate 8 in the case that the thickness becomes smaller.
FIGS. 9 and 12 to 14 are views which are referred for describing a conventional floor panel 20. The conventional floor panel 20 is constructed, as shown in FIG. 9, by mainly combining a top plate 26 in which an upper surface 26c is formed approximately as a square box shape, and a bottom plate 28 in which a bottom surface 28c corresponding to the upper surface 26c is formed approximately as a square box shape, vertically as shown in FIG. 12.
A side plate portion 26b is formed in the top plate 26 of the floor panel 20, the side plate portion 26b being formed by folding the top plate portion 26a approximately vertically from a peripheral edge portion thereof to a lower side in the drawing, and a side plate portion 28b is formed in the bottom plate 28 of the floor panel 20, the side plate portion 28b being formed by folding the bottom plate portion 28a approximately vertically from a peripheral edge portion thereof toward an upper side in the drawing, as shown in FIG. 13.
As a result, the top plate 26 is formed as a box shape having a concave space 26d which is formed in an inner side in a horizontal direction of the side plate portion 26b. Further, the bottom plate 28 is also formed as a box shape having a concave space 28d which is formed in an inner side in a horizontal direction of the side plate portion 28b. 
Further, in the floor panel 20, concave spaces 26d and 28d of the top plate 26 and the bottom plate 28 are arranged so as to be communicated with each other, and a peripheral edge portion 26j and a peripheral edge portion 28j are folded as a U-shaped form so as to enwrap respective leading end portions, thereby being connected in a joint portion 25 approximately in the center portion in a vertical direction in FIG. 13 of the floor panel 20, the peripheral edge portion 26j being formed in a lower end portion side of the side plate portion 26b of the top plate 26, and the peripheral edge portion 28j being formed in an upper end portion side of the side plate portion 28b of the bottom plate 28.
As mentioned above, since the top plate 26 and the bottom plate 28 are integrally connected in the joint portion 25, the floor panel 20 is formed as a hollow shape having an internal space 30. Further, a reinforcing member 32 having a thickness is provided in the internal space 30.
As mentioned above, since it is possible to make depths of the concave space 26d of the top plate 26 and the concave space 28d of the bottom plate 28 approximately half of a depth of the concave space 8d of the bottom plate in the floor panel 2, it is possible to make a height at which the side plate portions 26b and 28b are extended by a deep drawing process smaller than a height at which the side plate portion 8b of the bottom plate 8 is extended by a deep drawing process, at that degree.
As a result, since it is possible to reduce a tension force which is applied at the time of the deep drawing process of the top plate 26 and the bottom plate 28, it is possible to prevent a crack and a breaking from being easily generated at the time of the forming process even in the case that the thicknesses of the top plate 26 and the bottom plate 28 are reduced.
PRIOR ART DOCUMENT
Patent Document
Patent Document 1: Japanese Unexamined Patent Publication No. 2009-144378
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
However, in the conventional floor panel 2, as shown in FIG. 14, there is a problem that the joint portion 25 connecting the top plate 26 and the bottom plate 28 protrudes to an outer side in the horizontal direction (a right side in the drawing) in relation to the side plate portion 26b of the top plate 26, and a dimensional precision of the floor panel 20 is deteriorated.
In other words, as mentioned above, in the joint portion 25, the peripheral edge portion 26j formed in the lower end portion side of the side plate portion 26b in the top plate 26 and the peripheral edge portion 28j formed in the upper end portion side of the side plate portion 28b in the bottom plate 28 are folded as the U-shaped form so as to enwrap the respective leading end portions (refer to FIG. 13).
Further, the joint portion 25 is folded back approximately in parallel to the side plate portions 26b and 28b, and is pressed to a left side in FIG. 13 so as not to protrude to the outer side in the horizontal direction in relation to the side plate portion 26b. However, there is a case that the joint portion 25 protrudes to the outer side in the horizontal direction (the right side in the drawing) in relation to the outer peripheral surface (the right surface in the drawing) of the side plate portion 26b, due to a thereafter elastic deformation of the peripheral edge portions 26j and 28j, as shown in FIG. 14.
As a result, there is a case that the joint portion 25 protrudes to the outer side in the horizontal direction in relation to the outer peripheral surface of the side plate portion 26b in the top plate 26, the dimensional precision of the side surface portion of the floor panel 20 is deteriorated, and the joint portion 25 interferes with the other floor panel 20 which is arranged adjacently.
Further, in the case that the joint portion 25 protrudes to the outer side in the horizontal direction in relation to the outer peripheral surface of the side plate portion 26b in the top plate 26, the protruding joint portion 25 catches on the other member or a worker at the time of installing work of the floor panel 20 or the time of thereafter maintaining work, so that there is a problem that a workability is deteriorated.
Accordingly, the present invention is made by taking the problem mentioned above into consideration, and an object of the present invention is to provide a floor panel which can prevent a crack or a breaking from being easily generated at the time of forming process, and can improve a dimensional precision and a workability.
Means for Solving the Problem
In order to solve the problem mentioned above, according to the present invention, there is provided a floor panel comprising:
an upper member which has a concave space and a side surface having a height and is formed as a box shape;
a lower member which has a concave space and a side surface having a height and is formed as a box shape; and
the upper member and the lower member being combined up and down so as to communicate the respective concave spaces so as to form an internal space in an inner portion,
wherein the floor panel has a joint portion in which height leading end portions of the side surfaces of the upper member and the lower member are folded so as to enwrap each other so as to be connected, and
wherein the joint portion is arranged in a height midstream portion of the side surface of the floor panel, and is arranged at a position which is retreated to an inner side of the floor panel in relation to the side surface in both height end sides of the floor panel.
Further, according to the present invention, there is provided the floor panel, wherein the upper member has an upper concave portion which is formed so as to retreat to the inner side of the floor panel in relation to an upper end portion side of the side surface, in a lower end portion side of the side surface of the upper member,
wherein the lower member has a lower concave portion which is formed so as to retreat to the inner side of the floor panel in relation to a lower end portion side of the side surface, in an upper end portion side of the side surface of the lower member, and
wherein an upper peripheral edge portion formed in the lower end portion side of the upper concave portion and a lower peripheral edge portion formed in the upper end portion side of the lower concave portion are folded so as to enwrap each other, whereby the joint portion is formed.
Further, according to the present invention, there is provided the floor panel, wherein the upper member and the lower member are connected in a height center portion of the side surface of the floor panel.
Further, according to the present invention, there is provided the floor panel, wherein a reinforcing member is provided in the inner space which is formed between the upper member and the lower member.
Effect of the Invention
According to the floor panel of the present invention mentioned above, in the floor panel provided with the upper member which has the concave space and the side surface having the height and is formed as the box shape, and the lower member which has the concave space and the side surface having the height and is formed as the box shape, and structured such that the upper member and the lower member are combined up and down so as to communicate the respective concave spaces so as to form the internal space in the inner portion, the floor panel has the joint portion in which the height leading end portions of the side surfaces of the upper member and the lower member are folded so as to enwrap each other so as to be connected, and the joint portion is arranged in the height midstream portion of the side surface of the floor panel, and is arranged at the position which is retreated to the inner side of the floor panel in relation to the side surface in both height end sides of the floor panel. Accordingly, it is possible to prevent a crack or a breaking from being easily generated at the time of the forming work, and it is possible to improve a dimensional precision and a workability.



BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a top elevational view of a floor panel 40 according to an embodiment of the present invention;
FIG. 2 is a bottom elevational view of the floor panel 40 shown in FIG. 1;
FIG. 3 is a side elevational view showing an outline of the floor panel 40 shown in FIG. 1;
FIG. 4 is a cross sectional view of the floor panel 40 shown in FIG. 1 as seen from an arrow A-A;
FIG. 5 is a cross sectional view of the floor panel 40 shown in FIG. 1 as seen from an arrow B-B;
FIG. 6 is a cross sectional view of the floor panel 40 shown in FIG. 1 as seen from an arrow C-C;
FIG. 7 is a partly side elevational view showing a free access floor 41 which is constructed by the floor panel 40 shown in FIG. 1, and support legs 42 supporting the floor panel 40;
FIG. 8 is a partly perspective view showing a conventional free access floor 1 which is constructed by a conventional floor panel 2, and support legs 4 supporting the floor panel 2;
FIG. 9 is a top elevational view of the conventional floor panel 2 or 20;
FIG. 10 is a side elevational view showing an outline of the floor panel 2 shown in FIG. 9;
FIG. 11 is a cross sectional view of the floor panel 2 shown in FIG. 9 as seen from an arrow D-D;
FIG. 12 is a side elevational view showing an outline of the floor panel 20 shown in FIG. 9;
FIG. 13 is a cross sectional view of the floor panel 20 shown in FIG. 9 as seen from the arrow D-D; and
FIG. 14 is a cross sectional view of the floor panel 20 shown in FIG. 9 as seen from the arrow D-D, and is a view showing a state in which a joint portion 25 protrudes to an outer side in a horizontal direction of the floor panel 20 after a state in FIG. 13.



DESCRIPTION OF REFERENCE NUMERALS


    1 free access floor
    2 floor panel
    2a opening portion
    3 foundation floor surface
    4 support leg
    5 joint portion
    6 top plate
    6a top plate portion
    6b U-shaped portion
    6c upper surface
    6d concave space
    8 bottom plate
    8a bottom plate portion
    8b side plate portion
    8c bottom surface
    8d concave space
    8f peripheral edge portion
    10 internal space
    12 reinforcing member
    15 male thread member
    17 flat head bolt
    17a flat head portion
    17b male thread portion
    18 lid member
    20 floor panel
    20a opening portion
    25 joint portion
    26 top plate
    26a top plate portion
    26b side plate portion
    26c upper surface
    26d concave space
    26j peripheral edge portion
    28 bottom plate
    28a bottom plate portion
    28b side plate portion
    28c bottom surface
    28d concave space
    28j peripheral edge portion
    30 internal space
    32 reinforcing member
    40 floor panel
    40a opening portion
    41 free access floor
    44 top plate
    42 support leg
    44a top plate portion
    44b side plate portion
    44c upper surface
    44d concave space
    44e step receiving surface
    44f connection portion
    44g step receiving surface
    44h connection portion
    44j peripheral edge portion
    44m connection portion
    44k concave portion
    45 joint portion
    46 bottom plate
    46a bottom plate portion
    46b side plate portion
    46c bottom plate
    46d concave space
    46j peripheral edge portion
    46m connection portion
    46k concave portion
    50 reinforcing member
    56 panel adjusting table
    56a support surface
    56b female thread hole
    58 leg portion
    58a male thread portion


DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
A description will be specifically given below of a mode for carrying out a floor panel according to the present invention with reference to the accompanying drawings.
FIGS. 1 to 7 are views which are referred for describing a floor panel 40 according to an embodiment of the present invention.
The floor panel 40 according to the present embodiment is constructed, as shown in FIGS. 1 and 2, mainly by combining a top plate 44 (an upper member) in which an upper surface 44c is formed approximately as a square shape, and a bottom plate 46 (a lower member) in which a bottom surface 46c corresponding to the upper surface 44c is formed approximately as a square shape, from up and down as shown in FIG. 3.
The top plate 44 and bottom plate 46 are formed, for example, by a press drawing process while using a steel plate member such as SGCC. Further, the top plate 44 and the bottom plate 46 are combined vertically as shown in FIG. 4, and are connected in a joint portion 45 in a height center portion of a side surface of the floor panel 40.
As shown in FIG. 4, a side plate portion 44b is formed in the top plate 44 of the floor panel 40 by folding a top plate portion 44a of the top plate 44 approximately vertically from a peripheral edge portion toward a lower side in the drawing, and a connection portion 44m having an inclined surface inclined at a predetermined angle is formed from a lower end portion of the side plate portion 44b toward an inner direction (a leftward direction in the drawing) of the floor panel 40.
Further, a concave portion 44k (an upper concave portion) is formed in the top plate 44 so as to extend from a lower end portion of the connection portion 44m toward a lower side in FIG. 4 approximately in parallel to the side plate portion 44b, and a peripheral edge portion 44j (an upper peripheral edge portion) is formed so as to be folded at plural times like a U-shaped form from a leading end portion below the concave portion 44k. 
Further, a side plate portion 46b is formed in the bottom plate 46 of the floor panel 40, as shown in FIG. 4, by folding a bottom plate portion 46a approximately vertically from a peripheral edge portion of the bottom plate portion 46a toward an upper side in the drawing, and a connection portion 46m having an inclined surface in which the side plate portion 46b is inclined at a predetermined angle from an upper end portion of the side plate portion 46b toward an inner direction (a leftward direction in the drawing) of the floor panel 40.
Further, a concave portion 46k (a lower concave portion) is formed in the bottom plate 46, the concave portion 46k extending from an upper end portion of the connection portion 46m toward an upper side in the drawing so as to be approximately parallel to the side plate portion 46b, and a peripheral edge portion 46j (a lower peripheral edge portion) is formed by being folded as a U-shaped form from a leading end portion above the concave portion 46k, as shown in FIG. 4.
As a result, the top plate 44 is formed as a box shape having a concave space 44d which is formed in an inner side in a horizontal direction of the side plate portion 44b, the connection portion 44m, the concave portion 44k and the peripheral edge portion 44j and over a height direction. Further, the bottom plate 46 is formed in the same manner as a box shape having a concave space 46d which is formed in an inner side in a horizontal direction of the side plate portion 46b, the connection portion 46m, the concave portion 46k and the peripheral edge portion 46j and over a height direction.
Further, the top plate 44 and the bottom plate 46 are arranged so as to communicate the concave spaces 44d and 46d of the top plate 44 and the bottom plate 46 with each other, as shown in FIG. 4.
Further, as shown in FIG. 4, since the peripheral edge portion 44j of the top plate 44 and the peripheral edge portion 46j of the bottom plate 46 are folded like the U-shaped form so as to enwrap each other and be approximately in parallel to the side plate portions 44b and 46b, the top plate 44 and the bottom plate 46 are connected by the joint portion 45 approximately in the center portion in the vertical direction in FIG. 4 of the floor panel 40.
As mentioned above, since it is possible to make the depth of the concave space 44d of the top plate 44 and the concave space 46d of the bottom plate 46 approximately half of the depth of the concave space 8d of the bottom plate 8 in the conventional floor panel 2, it is possible to make a height with which the side plate portions 44b and 46b are extended by a deep drawing process smaller than a height with which the side plate portion 8b of the bottom plate 8 in the floor panel 2 is extended by a deep drawing process, at that degree.
Therefore, since it is possible to reduce a tension force which is applied in the case of the deep drawing process of the top plate 44 and the bottom plate 46, it is possible to prevent the crack or the breaking from being easily generated at the time of forming process even in the case that the thicknesses of the top plate 44 and the bottom plate 46 are reduced.
Further, the joint portion 45 formed by folding the peripheral edge portion 44j of the top plate 44 and the peripheral edge portion 46j of the bottom plate 46 is pressed toward the inner side of the floor panel 40 (the left side in FIG. 4) so as to come into contact with the concave portion 44k (refer to FIG. 4) of the top plate 44.
The concave portion 44k of the top plate 44 is formed at a position which is retreated to the inner side of the floor panel 40 in relation to the side plate portion 44b, and the concave portion 46k of the bottom plate 46 is formed at a position which is retreated to the inner side of the floor panel 40 in relation to the side plate portion 46b. 
As a result, the joint portion 25 pressed toward the inner side of the floor panel 40 is housed at a position which is retreated to the left side in FIG. 4 in relation to an outer peripheral surface of the side plate portion 44b and the side plate portion 46b (the right end surface in FIG. 4 of the floor panel 40).
In other words, the joint portion 45 is arranged in a height center portion of the side surface of the floor panel 40, and is arranged at a position which is retreated to the inner side of the floor panel 40 in relation to the side surfaces in both height end sides of the floor panel 40 (the outer peripheral surfaces of the side plate portions 44b and 46b), such that a single indented portion is formed between the upper and lower concave portions.
As a result, even in the case that the joint portion 45 deforms so as to return toward the outer side in the horizontal direction of the floor panel 40 (the right side in FIG. 4) due to a thereafter elastic deformation of the peripheral edge portions 44j and 46j, the joint portion 45 can be prevented from protruding to the outer side in the horizontal direction (the right side in FIG. 4) in relation to the outer peripheral surfaces of the side plate portions 44b and 46b (the right end surface in FIG. 4 of the floor panel 40).
Therefore, since the joint portion 45 connecting the top plate 44 and the bottom plate 46 does not protrude to the outer side in the horizontal direction in relation to the outer peripheral surfaces of the side plate portions 44b and 46b, it is possible to improve a dimensional precision of the side surface portion of the floor panel 40, and it is possible to prevent the joint portion 45 from interfering with the other floor panel 40 which is arranged adjacently.
Further, since the joint portion 45 does not protrude to the outer side in the horizontal direction in relation to the outer peripheral surfaces of the side plate portions 44b and 46b, the joint portion 45 can be prevented from catching on the other member or the worker at the time of installing the floor panel 40 or the time of the maintenance work after the installation, and it is possible to improve a workability.
Since the top plate 44 and the bottom plate 46 are integrally connected by the joint portion 45 (refer to FIGS. 4 to 6), the floor panel 40 can be formed as a hollow shape having an internal space 48, and a plate-like reinforcing member 50 having a thickness is housed in the internal space 48 in order to improve a strength of the floor panel 40.
The reinforcing member 50 is sandwiched between the top plate portion 44a of the top plate 44 and the bottom plate portion 46a of the bottom plate 46, and is provided so as to be along the side plate portions 44b and 46b and the concave portions 44k and 46k. Further, the reinforcing member 50 employs a particle board which is formed by breaking a wood into small wood pieces so as to dry, and molding under a high temperature and high pressure while adding an adhesive agent.
The top plate 44 of the floor panel 40 is formed, as shown in FIG. 1, in its four corner portions circular arc shaped connection portions 44f each of which is formed in its plane shape as a circular arc shape obtained by dividing a circle into four sections, and circular arc shaped step receiving surfaces 44e each of which is formed in its plane shape as a circular arc shape obtained by dividing a circle into four sections, in a radially inner side of the connection portion 44f. 
In other words, the connection portion 44f and the step receiving surfaces 44e are formed in each of four corner portions of the top plate 44, the connection portion 44f being formed as a taper shape which is inclined in its vertical cross section at a predetermined angle, and the step receiving surface 44e extending in parallel to the upper surface 44c of the top plate 44 (horizontally) from the lower end portion of the connection portion 44f and in a radial direction, and having a low step in relation to the upper surface 44c, as shown in FIG. 5.
Further, as shown in FIGS. 1 and 2, an opening portion 40a is formed in the floor panel 40 so as to intrude approximately like a rectangular shape into an inner side of a side edge portion of a lower edge (a lower side edge extending in a lateral direction of the drawing) which is one edge of the approximately square shape. The opening portion 40a is used for attaching a wall socket used for connecting an underfloor wiring to an office automation equipment installed on the floor panel 40.
Further, as shown in FIG. 6, a connection portion 44h and a step receiving surface 44g are formed in three edge portions which construct the opening portion 40a of the floor panel 40 and are formed approximately as a C-shaped form, the connection portion 44h being formed in its vertical cross section as a taper shape which is inclined at a predetermined angle, and the step receiving surface 44g extending from a lower end portion of the connection portion 44h in parallel to the upper surface 44c of the top plate 44 (horizontally) and in a width direction, and having a low step in relation to the upper surface 44c. The step receiving surface 44g is formed along three edge portions which construct the opening portion 40a of the floor panel 40 and are formed approximately as a C-shaped form.
Further, the opening portion 40a of the floor panel 40 is structured such as to be closed by brining a lower surface of a plate-like lid member 18 (refer to FIG. 8) into contact with the step receiving surface 44g of the top plate 44, the lid member 18 being formed so that its upper surface approximately forms the same plane shape as the upper surface 44c of the top plate 44.
Since the floor panel 40 is structured, as shown in FIGS. 5 and 6, such that the reinforcing member 50 is sandwiched between the step receiving surfaces 44e and 44g of the top plate 44, and the bottom plate portion 46a of the bottom plate 46 below the step receiving surfaces, the step receiving surfaces 44e and 44g can be improved its strength, and are hard to be deflected. As a result, it is possible to prevent the step receiving surfaces 44e and 44g from being deformed in the case that the load is applied from the upper side of the step receiving surfaces 44e and 44g. 
Further, since the lid member 18 (refer to FIG. 8) mounted on the step receiving surface 44g of the top plate 44 can support the load applied from the upper side thereof with the step receiving surface 44g, it is possible to prevent the lid member 18 from being deformed.
The floor panel 40 is structured, as shown in FIG. 7, such as to construct a free access floor 41 together with support legs 42 which are provided in a rising manner on the foundation floor surface 3. Further, the support leg 42 supporting the floor panel 40 is constructed by a panel adjusting table 56 and a leg portion 58.
The panel adjusting table 56 of the support leg 42 adjusts a height position of the panel adjusting table 56 from the foundation floor surface 3 by relatively rotating the panel adjusting table 56 along a spiral track of a male thread portion 58a in a state in which the male thread portion 58a formed in an outer peripheral portion of the leg portion 58 is threadably joined to a female thread portion formed in a lower end side of an axial portion of the panel adjusting table 56.
Further, the panel adjusting table 56 is fixed to a desired height position from the foundation floor surface 3 by fastening a male thread member 15 to a female thread hole which is formed in a lower end portion of the panel adjusting table 56 and extends its axis in a radial direction.
A plurality of floor panels 40 are mounted on a support surface 56a of the panel adjusting table 56 in such a manner that four corner portions of the bottom surfaces 46c of a plurality of floor panels 40 are gathered to one position and confronted. Further, the step receiving surfaces 44e in four corner portions of the top plate 44 are pressed downward by a flat head portion 17a of a flat head bolt 17, by fastening a male thread portion 17b of the flat head bolt 17 into a female thread hole 56b in an upper end side of an axial portion of the panel adjusting table 56, and the floor panel 40 is fixed onto the support surface 56a of the panel adjusting table 56.
Semispherical concave portions 46e depressed to the upper surface 44c side of the top plate 44 (an upper side in FIG. 3) are formed in four corner portions of the bottom surface 46c of the bottom plate 46, as shown in FIG. 2. Further, since the concave portions 46e are fitted to semispherical convex portions provided in the support surface 56a in the case that four corner portions of the bottom surface 46c are mounted onto the support surface 56a of the panel adjusting table 56, the floor panel 40 mounted on the support legs 42 can be easily positioned.
Therefore, as described above, according to the floor panel 40 on the basis of the present embodiment, it is possible to prevent the crack or the breaking from being easily generated at the forming time, and it is possible to improve a dimensional precision and a workability.
The present invention is not limited only to the embodiment mentioned above, but can be variously modified in the floor panel as long as the purpose of the present invention can be achieved.
For example, in the floor panel 40 according to the embodiment mentioned above, the joint portion 45 connecting the top plate 44 and the bottom plate 46 is formed in the center portion in the height direction of the side surface of the floor panel 40, however, can be formed at the other positions in the height midstream portion of the side surface of the floor panel 40 without being limited to the position mentioned above.
Further, in the floor panel 40 according to the embodiment mentioned above, the connection portion 44m is formed so as to have the inclined surface which is inclined at the predetermined angle from the lower end portion of the side plate portion 44b of the top plate 44 toward the inner direction of the floor panel 40, and the connection portion 46m is formed so as to have the inclined surface which is inclined at the predetermined angle from the upper end portion of the side plate portion 46b of the bottom plate 46 toward the inner direction of the floor panel 40, however, the connection portions 44m and 46m are not limited to these shapes.
For example, the connection portions 44m and 46m may be formed as a vertical plate shape which connects so that approximately perpendicular steps are respectively formed between the side plate portions 44b and 46b, and the concave portions 44k and 46k, or may be formed so that a vertical cross section of the inclined surface of each of the connection portions 44m and 46m is formed as a circular arc shape.
Further, in the floor panel 40 according to the embodiment mentioned above, the peripheral edge portion 44j of the top plate 44 and the peripheral edge portion 46j of the bottom plate 46 are folded like the U-shaped form so as to enwrap each other, whereby the top plate 44 and the bottom plate 46 are connected by the joint portion 45, as shown in FIG. 4, however, the folding method is not limited to the above, but, for example, the folding number of the peripheral edge portions 44j and 46j and the lengths thereof may be different.
Further, in the floor panel 40 according to the embodiment mentioned above, the plate-like reinforcing member 50 using the particle board is installed within the internal space 48, however, the other wooden material than the particle board may be installed within the internal space 48, a reinforcing member formed by the other materials than the wooden material may be installed within the internal space, or nothing may be installed within the internal space 48.
In the case that the reinforcing member formed by the other material such as a mortar than the wooden material is used, a fluid material may be filled, for example, from a hole formed in the top plate portion 44a into the internal space 48 of the floor panel 40 which is formed by the upper member 44 and the lower member 46 so as to be solidified according to passage of time, in place of the member formed as the plate shape.
Further, the floor panel 40 according to the embodiment mentioned above is formed by using a steel plate member, however, may be formed by using the other material such as an aluminum without being limited to the steel plate material.
Further, FIG. 8 shows the case that one support leg 4 put in the center of the drawing supports three floor panels 2 while gathering the corner portions thereof as a matter of convenience for description, however, it goes without saying that one support leg 4 can support four floor panels 2 while gathering the corner portions thereof, and this is an original using way of the support leg 4 and is applied in the same manner to the floor panel 40 according to the present embodiment.

## Claims

1. A floor panel comprising:
an upper member which has an upper surface and a side surface and is formed as a box shape with a concave space;
shape with a concave shape; and
said upper member and said lower member being combined at a lower end of the side surface of said upper member and an upper end of the side surface of said lower member so as to communicate the respective concave spaces so as to form an internal space in an inner portion,
said side surfaces of the upper member and the lower member defining a side surface of the floor panel,
wherein a part of said lower end of the side surface of said upper member and a part of said upper end of the side surface of said lower member are bent toward an inner side of said floor panel to provide an upper concave portion and a lower concave portion formed on the inner side of the floor panel in relation to the side surface of the floor panel, said upper and lower concave portions forming a single indented portion therebetween,
wherein said floor panel has a joint portion in which leading end portions of peripheral edge portions of the side surfaces of the upper member and the lower member are folded back on each other so as to enwrap each other so as to be connected, and to form said internal space;
wherein said joint portion is arranged in a midstream portion of the side surface of said floor panel, and arranged in said single indented portion of said floor panel.

2. The floor panel according to claim 1,
wherein an upper peripheral edge portion formed in the lower end portion side of said upper concave portion and a lower peripheral edge portion formed in the upper end portion side of said lower concave portion are folded back on each other so as to enwrap each other, whereby said joint portion is formed.

3. The floor panel according to claim 2, wherein said upper member and said lower member are connected in a center portion of the side surface of said floor panel.

4. The floor panel according to claim 2, wherein a reinforcing member is provided in said inner space which is formed between said upper member and said lower member.

5. The floor panel according to claim 3, wherein a reinforcing member is provided in said inner space which is formed between said upper member and said lower member.

6. The floor panel according to claim 1, wherein said upper member and said lower member are connected in a center portion of the side surface of said floor panel.

7. The floor panel according to claim 6, wherein a reinforcing member is provided in said inner space which is formed between said upper member and said lower member.

8. The floor panel according to claim 1, wherein a reinforcing member is provided in said inner space which is formed between said upper member and said lower member.