Tread for stair and stair

Abstract

To provide a tread for stairs which is light and in which bent deflection hardly occurs, and to provide stairs including the same.SOLUTION: A tread 2 includes: a core material 10 comprising a rectangular plate-like body; frame materials 20, 20 provided on the front side and the rear side of the core material 10; and two surface materials 30, 30 fixed to an upper end surface and a lower end surface of the frame materials 20, 20 respectively. The core material 10 includes: a rectangular plate-like core 11 in which a plurality of holes 11a,...,11a extends in the thickness direction of the core material 10; and two sheets 12, 12 attached to an upper surface and a lower surface of the core 11. The upper surface material 30 is attached to the upper end surface of the frame material 20 and the upper sheet 12 constituting the upper surface of the core material 10, and the lower surface material 30 is attached to the lower sheet 12 constituting the lower end surface of the frame material 20 and the lower surface of the core material 10.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a stair tread and a staircase equipped with the same. [Background technology]

[0002] Conventionally, stair treads for use in buildings such as houses have been proposed that incorporate honeycomb material within a panel-like body with surface panels arranged on both sides of a frame material (see, for example, Patent Document 1 below).

[0003] The stair tread described in Patent Document 1 has a honeycomb material built into a main body that includes a rectangular frame made up of four frame bodies, a reinforcing core material that connects the centers of the two long-side frame bodies within the rectangular frame, and two surface materials that are fixed to the upper and lower surfaces of the rectangular frame and close both the top and bottom surfaces.The honeycomb material has multiple holes that extend in the thickness direction (front-to-back direction) within the main body.In this way, by using honeycomb material instead of laminated wood or plywood as a core material in conventional stair treads, it is possible to manufacture it lightweight and inexpensively, and it is also able to absorb shocks when going up and down. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 57-159933 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional stair treads, the two surface materials of the main body are fixed to a rectangular frame (four frames), not to the honeycomb material. Therefore, when a bending load is applied to conventional stair treads, although the honeycomb material can support the load, there is a problem in that the treads are prone to bending deformation and bending deflection.

[0006] In addition, in conventional stair treads, it is possible to make the frame less susceptible to bending by constructing it from a thick material with high bending strength, but such a structure has the problem that it is not possible to achieve significant weight reduction.

[0007] The present invention has been made in view of the above points, and its object is to provide a lightweight stair tread that is less susceptible to bending, and a staircase equipped with the same. [Means for solving the problem]

[0008] In order to achieve the above object, in this invention, a rectangular plate-shaped core having a plurality of holes extending in the thickness direction and having sheet-like materials adhered to the upper and lower surfaces is used as the core material of the stair tread, and two surface materials are adhered not only to the frame material but also to the core material.

[0009] Specifically, the first invention is a stair tread comprising a core material consisting of a rectangular plate-shaped body, a frame material provided at least on the front and rear sides of the core material, and two surface materials fixed to the upper and lower end surfaces of the frame material, respectively; the core material has a rectangular plate-shaped core with a plurality of holes extending in the thickness direction of the core material, and two sheet-like materials adhered to the upper and lower surfaces of the core, the upper surface material being adhered to the upper end surface of the frame material and the upper sheet-like material constituting the upper surface of the core material, and the lower surface material being adhered to the lower end surface of the frame material and the lower sheet-like material constituting the lower surface of the core material.

[0010] Here, the term "sheet-like object" includes paper, resin sheets, thin plates, etc., having a thickness of 0.01 mm or more and 10 mm or less.

[0011] In the first invention, the core material of the stair tread is a rectangular plate-shaped core with multiple holes extending in the thickness direction and sheets bonded to the upper and lower surfaces, resulting in a lightweight stair tread with excellent bending strength. Furthermore, in the first invention, sheets are bonded to the upper and lower surfaces of the core that constitutes the core material, and two surface materials are bonded not only to the frame material but also to the sheets that constitute the upper and lower surfaces of the core. Because the upper and lower surfaces of the core have multiple holes, directly bonding (directly attaching) thick surface materials to the core's upper and lower surfaces makes the surface materials prone to peeling. In the first invention, sheet materials thinner than the surface materials are bonded to the upper and lower surfaces of the core, and then the thick surface materials are bonded to the sheet materials. When attached to the upper and lower surfaces of the core, sheet materials thinner than the surface materials are less likely to peel than when thick surface materials are attached. Furthermore, the two thick surface materials are bonded in surface contact with the upper and lower surfaces (sheet-like materials) of the core material, which has excellent bending strength, resulting in significantly higher peel strength (less likely to peel) than when they are directly attached to the upper and lower surfaces of the core. By firmly bonding the two surface materials in surface contact with the core material, which has excellent bending strength, the stair tread is less likely to bend or deflect when a bending load is applied. Therefore, according to the first invention, a lightweight stair tread that is less likely to bend or deflect can be provided.

[0012] A second invention is characterized in that in the first invention, the frame material is provided only on the front and rear sides of the core material.

[0013] In the second invention, the frame members are provided only on the front and rear sides of the core, not on either the left or right side of the core. As described above, in the above stair tread, the two surface panels are firmly bonded in surface contact with the upper and lower surfaces of the core, which has excellent bending strength. Therefore, unlike conventional stair treads, there is no need to provide a frame member around the core to secure the two surface panels. It is sufficient to provide a frame member on the front and rear sides of the core to secure the risers. Furthermore, providing a frame member around the core requires more manual work and labor, which reduces manufacturing efficiency. However, according to the second invention, the frame members are provided only on the two long side surfaces (front and rear) of the core. This allows the frame members to be attached to the core without changing the direction of the manufacturing line, resulting in a lighter stair tread that is easier to manufacture.

[0014] A third invention is characterized in that, in the first or second invention, the core is made of paper.

[0015] In the third aspect of the present invention, a paper core is used as the core material of the stair tread, thereby making it possible to provide a lighter stair tread.

[0016] A fourth invention is the third invention, characterized in that the sheet-like material is paper.

[0017] In the fourth invention, a paper core with paper glued to its upper and lower surfaces is used as the core material for a stair tread. The core's upper and lower surfaces are perforated with multiple holes, making it difficult to adhere sheet-like materials to them. However, by using paper for both the core and the sheet-like materials, it becomes easier to adhere the sheet-like materials to the core. This core material allows the sheet-like materials to be firmly fixed (glued) to the core, making it less likely to bend or deform when a bending load is applied to the stair tread. Therefore, the fourth invention provides a stair tread that is less likely to bend or deform.

[0018] A fifth invention is characterized in that, in the first or second invention, the surface material is made of a medium density fiberboard.

[0019] In recent years, due to the wood shock and plywood shock, it has become difficult to obtain imported plywood, and efforts are being made to replace it with other wood boards such as fiberboard. Among these, medium-density fiberboard has a relatively smooth surface and excellent water resistance (water repellency), making it highly suitable for interior materials. However, due to its high density, medium-density fiberboard, when used alone as a stair tread, is heavy and difficult to install. Therefore, in the fifth invention, the two surface materials of the stair tread are made of medium-density fiberboard, while the core material is made of a core with sheet-like materials bonded to the upper and lower surfaces. This makes it possible to provide a lightweight stair tread that is less susceptible to bending.

[0020] The sixth invention is characterized in that, in the first or second invention, the surface material is made of a composite material in which medium-density fiberboard and veneer are laminated and bonded, and the medium-density fiberboard is fixed to the core material and the frame material so that it is located on the surface side of the stair tread.

[0021] As mentioned above, medium-density fiberboards have a relatively smooth surface and excellent water resistance (water repellency) compared to other wood boards, making them highly suitable for interior use. However, their bending performance (bending strength and Young's modulus in bending) is inferior to that of veneers. Therefore, in the sixth invention, the surface material is a composite material made by laminating and bonding medium-density fiberboard and veneer together, and this composite material is fixed to the frame and core material so that the medium-density fiberboard, which has a smooth surface and excellent decorative properties, is located on the surface side of the stair tread. This makes it possible to provide a stair tread with excellent decorative properties (surface smoothness), water resistance (water repellency), and bending performance.

[0022] The seventh invention is a staircase provided with a plurality of stair treads, characterized in that the stair treads are the stair treads according to the first or second invention.

[0023] In the seventh aspect of the present invention, the above-mentioned lightweight stair treads that are resistant to bending are used for stairs, making it possible to easily construct stairs that are resistant to bending and have excellent strength. [Effects of the Invention]

[0024] As described above, according to the present invention, a rectangular plate-shaped core having a plurality of holes extending in the thickness direction and having sheet-like materials adhered to the upper and lower surfaces is used as the core material of a stair tread, and two surface materials are adhered not only to the frame material but also to the core material, thereby providing a lightweight stair tread that is less susceptible to bending. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view showing a part of the staircase according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a part of the staircase according to the first embodiment. [Figure 3] FIG. 3 is an exploded perspective view of a stair tread. [Figure 4] FIG. 4 is a perspective view showing a stair tread with a portion cut away. [Figure 5] FIG. 5 is a cross-sectional view showing a part of the staircase according to the second embodiment. [Figure 6] FIG. 6 is an enlarged view of a portion VI in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are merely preferred examples in nature and are not intended to limit the scope of the present invention, its applications, or its uses.

[0027] First Embodiment of the Invention -Staircase configuration- As shown in Figures 1 and 2, the staircase S is a straight staircase that connects the upper and lower floors without bending within a building such as a house, and in the following explanation, the front side of the staircase S going up will be referred to as the "front," the back side as the "rear," the left side as the "left," and the right side as the "right."

[0028] The staircase S includes, for example, a pair of side girders 1, 1 arranged opposite each other in the left-right direction, a plurality of treads (stair treads) 2, ..., 2, and a plurality of risers 3, ..., 3 spanning between the front end of each tread 2 and the rear end of the tread 2 of the step below. Note that in this embodiment 1, an example will be described in which the staircase S is a side girder staircase including a pair of side girders 1, 1, but the staircase S may not include a pair of side girders 1, 1, or may include a side girder 1 on only one of the left and right sides.

[0029] The pair of stringers 1,1 are each made of, for example, long, narrow wooden boards. The pair of stringers 1,1 are arranged parallel to each other with a slope that increases in height toward the rear in the front-to-rear direction, and are fixed to the floor, wall, etc. The front ends of the pair of stringers 1,1 are cut vertically from top to bottom, and the lower ends are cut horizontally from front to back and abut against the floor surface F. The opposing surfaces of the pair of stringers 1,1 are formed with a plurality of tread grooves (not shown) into which the left and right ends of a plurality of treads 2,...,2 fit, and a plurality of riser grooves (not shown) into which the left and right ends of a plurality of risers 3,...,3 fit. The tread grooves extend horizontally in the front-to-rear direction, and the riser grooves extend vertically. The tread grooves and riser grooves are formed alternately and continuously on each opposing surface of the pair of stringers 1,1.

[0030] The multiple treads 2,...,2 are rectangular plate-like members that are spanned between the pair of stringers 1,1. The detailed configuration of the treads 2 will be described later. The multiple treads 2,...,2 are fixed to the pair of stringers 1,1 with their left and right ends inserted into tread grooves formed on the opposing surfaces of the pair of stringers 1,1.

[0031] The multiple risers 3,...,3 are rectangular plate-like members that are thinner (about 6 to 18 mm) than the treads 2 and can be made of, for example, plywood, particle board, medium density fiberboard, composite plywood, laminated lumber, etc. The multiple risers 3,...,3 are provided between the multiple treads 2,...,2 and between the lowest tread 2 and the floor surface F.

[0032] The multiple risers 3,...,3 span between the front ends of the multiple treads 2,...,2 and the rear ends of the treads 2 one level below or the floor surface F. The multiple risers 3,...,3 also span between a pair of stringers 1,1. The multiple risers 3,...,3 are fixed to the pair of stringers 1,1 with adhesive, with their left and right ends inserted into riser grooves formed on the opposing surfaces of the pair of stringers 1,1. The upper end of each riser 3 spanning between the multiple treads 2,...,2 is inserted into a riser groove 2a (described later) formed in the front end of the upper tread 2, and the lower end of its front face abuts against the rear end surface of the lower (one level below) tread 2, with the riser 3 fixed to the upper and lower treads 2,2 with nail-like members 4,4 such as nails or screws. The lowermost riser 3 is fixed to the lowermost tread 2 and the floor with nail-like members 4, 4, with its upper end inserted into a riser groove 2a formed in the lowermost tread 2 and its lower end abutting the floor surface F or inserted into a riser groove formed in the floor surface F.

[0033] <Detailed structure of the tread> 2 to 4, the step board 2 comprises a core material 10 that is a flat, rectangular plate in plan view, two frame materials 20, 20 provided on the front and rear sides of the core material 10, and two surface materials 30, 30 provided above and below the core material 10. The step board 2 is formed to have a depth (length in the front-to-rear direction) of approximately 180 to 300 mm, a width (length in the left-to-right direction) of approximately 750 to 1200 mm, and a thickness of approximately 25 to 40 mm. In this embodiment 1, the step board 2 is formed to have a depth of 260 mm, a width of 1000 mm, and a thickness of 36 mm.

[0034] The core material 10 has a predetermined thickness (height) and includes a rectangular plate-shaped core 11 with a plurality of holes 11a extending in the thickness direction, and two sheets of paper (sheet-like objects) 12, 12. In the present embodiment 1, the core material 10 is formed to have dimensions of 180 mm in depth, 1000 mm in width, and 28 mm in thickness.

[0035] Furthermore, in this embodiment 1, a paper core formed by bonding pieces of paper together with an adhesive is used as the core 11. Any paper may be used for the paper core 11, but from the viewpoint of inexpensively forming a core 11 with excellent bending strength, it is preferable to use corrugated cardboard. Furthermore, in this embodiment 1, a core 11 with excellent water resistance is used, in which paper coated with a water-resistant agent is bonded with a water-resistant adhesive. Note that the method of imparting water resistance to paper is not limited to applying a water-resistant agent; a resin may be applied instead of the water-resistant agent, or the paper may be impregnated with a water-resistant agent or a resin.

[0036] In this embodiment 1, a core 11 is used in which no decorative sheet is attached to the outer periphery (end grain surface), and the outermost holes 11a are exposed. If the paper constituting the core 11 is not water-resistant or has low water resistance, it is preferable to apply or impregnate a water-resistant agent or resin to the outer periphery of the core 11. The core 11 may also have a decorative sheet attached to the outer periphery. The decorative sheet attached to the outer periphery of the core 11 is preferably made of a water-resistant material, or is made water-resistant by applying or impregnating it with a water-resistant agent or resin.

[0037] The material of the core 11 does not have to be paper, and any material may be used as long as the density of the core material 10 is smaller than that of the surface materials 30, 30, preferably less than half the density of the surface materials 30, 30, and more preferably less than one-tenth the density of the surface materials 30, 30. The thickness of the core 11 used in the core material 10 of the stair tread 2 is preferably 10 mm or more and 40 mm or less. In this embodiment 1, the density is 0.05 g / cm 3 The core 11 has a thickness of 26 mm. In the first embodiment, the upper and lower surfaces of the core 11 are roughened (fluffed) using a file or the like.

[0038] The paper sheets 12, 12 adhered to the upper and lower surfaces of the core 11 may be made of any material and thickness as long as they are thinner than the surface material 30, have good adhesion to the core 11, and are strong enough not to break when a bending load is applied to the tread 2. In this embodiment 1, cardboard with a thickness of 1 mm is used. The paper sheets 12, 12 are formed to have the same shape (same rectangular shape) as the core 11 in a plan view, so as to cover the entire upper or lower surface of the core 11. The paper sheets 12, 12 are adhered to the entire upper and lower surfaces of the core 11. Any adhesive may be used to adhere the paper sheets 12, 12 to the core 11 as long as it can bond the two, but it is preferable to use a water-resistant adhesive.

[0039] In this embodiment 1, the core 11 is made of paper, and the sheet-like material 12 attached to the upper and lower surfaces of the core 11 is also made of paper 12. In other words, the core 11 and the sheet-like material 12 are made of the same material. Therefore, the upper and lower surfaces of the core 11 have a plurality of holes 11a, which makes it difficult to adhere the sheet-like material 12 to them. However, by using paper for both the core 11 and the sheet-like material 12, it becomes easier to adhere the sheet-like material 12 to the core 11. In this embodiment 1, the upper and lower surfaces of the core 11 are made rough (fluffy), which also makes it easier to adhere the sheet-like material 12, which is paper.

[0040] The frame material 20 is made of wooden rod-shaped members (square lumber) with a rectangular cross section. The frame material 20 is configured to have a thickness equal to the thickness of the core material 10 (the thickness of the core 11 plus the thickness of the two sheets of paper 12, 12) and a width equal to the width (length in the left-right direction) of the core material 10. In this embodiment 1, the frame material 20 is made of laminated veneer lumber with a depth of 40 mm, a width of 1000 mm, and a thickness of 28 mm. Note that the frame material 20 may be made of a material other than laminated veneer lumber, as long as it is strong enough to hold the nail-shaped members 4, 4 for fixing the riser 3, and plywood, lumber, etc. can be used.

[0041] Of the two frame materials 20, 20, the frame material 20 provided on the front side of the core material 10 has a recessed groove with a rectangular cross section formed on its underside that serves as the riser plate groove 2a. The recessed groove is formed with a groove width (length in the front-to-rear direction) that allows the upper end of the riser plate 3 to fit into. The recessed groove is formed to extend from the left end to the right end of the underside of the frame material 20. The recessed groove of the frame material 20 constitutes the riser plate groove 2a together with linear holes in the surface material 30, which will be described later and is adhered to the underside of the frame material 20. The recessed groove of the frame material 20 is formed at the same time as the linear holes in the surface material 30 by performing a cutting process after the surface material 30 has been adhered to the underside of the frame material 20.

[0042] The two surface materials 30, 30 have a density (g / cm 3 In the first embodiment, the two surface materials 30, 30 are made of a medium density fiberboard having a density of 0.7 g / cm3 or more and less than 1.00 and a thickness of about 2 to 20 mm. 3 The core material 10 is made of a 4 mm thick medium density fiberboard. From the viewpoint of suppressing warping, it is preferable that the thicknesses of the two surface materials 30, 30 provided above and below the core material 10 are the same, but the thicknesses of the two surface materials 30, 30 provided above and below the core material 10 may be different.

[0043] The medium-density fiberboards constituting the two surface materials 30, 30 preferably contain an adhesive with excellent water resistance, and in this embodiment 1, the two surface materials 30, 30 are made of medium-density fiberboards containing a urea-melamine co-condensation resin adhesive. The adhesive used for the medium-density fiberboard is not limited to a urea-melamine co-condensation resin adhesive, but may also contain diphenylmethane diisocyanate, phenol resin, or the like, and if a decorative sheet is attached to the outermost layer, a medium-density fiberboard containing an adhesive with low water resistance, such as urea resin, may also be used.

[0044] The two surface materials 30, 30 are formed to a size that can cover the upper surface of the core material 10 (the upper paper 12 adhered to the upper surface of the core 11) and the upper surfaces of the two frame materials 20, 20, or the lower surface of the core material 10 (the lower paper 12 adhered to the lower surface of the core 11) and the lower surfaces of the two frame materials 20, 20. In this embodiment 1, the two surface materials 30, 30 are each formed to a depth of 260 mm, a width of 1000 mm, and a thickness of 4 mm.

[0045] The two surface materials 30, 30 are respectively adhered to the two frame materials 20, 20 and the core material 10. Specifically, the upper surface material 30 is adhered to the entire upper end surfaces of the two frame materials 20, 20 and the entire upper surface of the upper paper 12 that forms the upper surface of the core material 10, and the lower surface material 30 is adhered to the entire lower end surfaces of the two frame materials 20, 20 and the entire lower surface of the lower paper 12 that forms the lower surface of the core material 10. Any adhesive may be used to adhere the two surface materials 30, 30 to the frame material 20 and the core material 10 as long as it can bond them together, but it is preferable to use a water-resistant adhesive.

[0046] The tread 2 is a sandwich panel made by sandwiching a core material 10 consisting of a core 11 with paper (sheet-like material) 12 attached to the top and bottom surfaces between two surface materials 30, 30 made of medium-density fiberboard, and bonding them together with a water-resistant adhesive. By giving the tread 2 a three-layer structure in this way, and by constructing the core material 10 from the core 11, which has a significantly lower density and is lighter than the medium-density fiberboard used in the surface material 30, and two sheets of paper 12, 12, the weight of the tread 2 can be reduced.

[0047] In this embodiment 1, as shown in Figure 2, a decorative material 5 such as a decorative sheet or veneer is attached to the exposed surfaces (upper surface, front surface and front end of the lower surface) of the tread 2 that are exposed after construction of the staircase S.

[0048] Furthermore, in the tread 2, the core material 10 is not simply composed of a core 11, but rather has paper (sheet-like materials) 12, 12 attached to the upper and lower surfaces of the core 11. By attaching paper (sheet-like materials) 12, 12 that is thinner than the surface material 30 and less likely to peel off to the upper and lower surfaces of the core 11 in this way, the upper and lower surfaces (paper 12) of the core material 10 can be firmly bonded to the surface materials 30, 30 in a state of surface contact.

[0049] -Effects of the first embodiment- In this embodiment 1, the core material 10 of the step 2 is made up of a rectangular plate-shaped core 11 with multiple holes 11a extending in the thickness direction and with paper (sheet-like materials) 12, 12 adhered to the upper and lower surfaces, thereby providing a lightweight step 2 with excellent bending strength. Also, in this embodiment 1, the papers 12, 12 are adhered to the upper and lower surfaces of the core 11 that constitutes the core material 10, and the two surface materials 30, 30 are adhered not only to the frame materials 20, 20 but also to the papers 12, 12 that constitute the upper and lower surfaces of the core material 10. Because the upper and lower surfaces of the core 11 have a plurality of holes 11a, if thick surface materials 30, 30 were directly bonded (directly attached) to the upper and lower surfaces of the core 11, the surface materials 30, 30 would be prone to peeling. However, in the first embodiment, paper (sheet-like materials) 12, 12 thinner than the surface materials 30, 30 are bonded to the upper and lower surfaces of the core 11, and then the thick surface materials 30, 30 are bonded to the paper 12, 12. When the paper (sheet-like materials) 12, 12 thinner than the surface materials 30, 30 are attached to the upper and lower surfaces of the core 11, they are less likely to peel than when the thick surface materials 30, 30 are attached. Furthermore, because the two thick surface materials 30, 30 are bonded in surface contact with the upper and lower surfaces (paper 12) of the core material 10, which has excellent bending strength, the peel strength is significantly higher (less likely to peel) than when they are directly attached to the upper and lower surfaces of the core 11. In this way, the two surface materials 30, 30 are firmly bonded in surface contact with the core material 10, which has excellent bending strength, making it difficult for the tread 2 to bend or deflect when a bending load is applied to the tread 2. Therefore, according to the first embodiment, it is possible to provide a lightweight tread 2 that is difficult to bend or deflect.

[0050] Furthermore, in the tread 2 of the first embodiment, the frames 20, 20 are provided only on the front and rear sides of the core material 10, not on either the left or right side of the core material 10. As described above, in the tread 2, the two surface materials 30, 30 are firmly bonded in surface contact with the top and bottom surfaces of the core material 10, which has excellent bending strength. This eliminates the need for frames around the core material to secure the two surface materials, as in conventional stair treads. Instead, it is sufficient to provide frames 20 on the front and rear sides of the core material 10 to secure the risers 3, 3. Furthermore, providing frames around the core material would require more manual work and increased labor, thereby reducing manufacturing efficiency. However, in the first embodiment, the frames 20 are provided only on the two long side surfaces (front and rear) of the core material 10. This allows the frames 20 to be attached to the core material 10 without changing the direction of the manufacturing line, resulting in a tread 2 that is easier to manufacture and lighter in weight.

[0051] Furthermore, in the first embodiment, the core 11 made of paper is used as the core material 10 of the step board 2, so that a lighter step board 2 can be provided.

[0052] Furthermore, in this first embodiment, a paper core 11 with paper sheets 12, 12 adhered to its upper and lower surfaces is used as the core material 10 of the tread 2. The upper and lower surfaces of the core 11 are perforated with multiple holes 11a, making it difficult to adhere a sheet-like material thereto. However, by using paper for both the core 11 and the sheet-like material (paper core 11 and paper sheets 12, 12), it becomes easier to adhere the sheet-like material to the core 11. This type of core material 10 allows the sheet-like material to be firmly fixed (adhered) to the core 11, making it less likely to bend or deform when a bending load is applied to the tread 2. Therefore, this first embodiment can provide a tread 2 that is less likely to bend or deform.

[0053] Furthermore, in this embodiment 1, because medium density fiberboard has a high density, when used for the tread 2, it increases the weight and makes it difficult to install. However, in the tread 2, the two surface materials 30, 30 are made of medium density fiberboard, while the core material 10 is made of a core 11 with sheet-like materials (paper 12, 12) adhered to the upper and lower surfaces, thereby providing a tread 2 that is lightweight and less prone to bending.

[0054] Furthermore, in the present embodiment 1, the treads 2 that are lightweight and resistant to bending are used for the stairs S. Therefore, the stairs S that are resistant to bending and have excellent strength can be easily constructed.

[0055] Second Embodiment of the Invention In the second embodiment, the configuration of the step 2 in the first embodiment is changed.

[0056] As shown in Figures 5 and 6, in embodiment 2, the tread 2 also comprises a core material 10 that is rectangular in plan view and flat, two frame materials 20, 20 provided on the front and rear sides of the core material 10, and two surface materials 30, 30 provided above and below the core material 10, but the thickness of the core material 10 and the configuration of the surface material 30 differ from those in embodiment 1.

[0057] In the second embodiment, the core material 10 also has a rectangular plate-shaped core 11 and two sheets of paper (sheet-like materials) 12, 12. In the second embodiment, the core material 10 has the same planar dimensions as in the first embodiment (depth 180 mm, width 1000 mm), but is thinner than in the first embodiment, at 23 mm (28 mm in the first embodiment). The other configurations of the core material 10 are the same as in the first embodiment.

[0058] In the second embodiment, the surface material 30 is made of a composite material in which first and second plate materials 31, 32, which are flat and rectangular in plan view, are laminated and bonded with an adhesive. The surface material 30 is fixed to the core material 10 and the frame material 20 so that the first plate material 31 is located on the surface side of the tread 2 and the second plate material 32 is located on the core material 10 side. The first and second plate materials 31, 32 that make up the surface material 30 are formed to a size (depth 260 mm, width 1000 mm in the second embodiment) that can cover the upper surface of the core material 10 (the upper paper 12 bonded to the upper surface of the core 11) and the upper surfaces of the two frame materials 20, 20, or the lower surface of the core material 10 (the lower paper 12 bonded to the lower surface of the core 11) and the lower surfaces of the two frame materials 20, 20.

[0059] The first plate material 31 has a density (g / cm 3 In the second embodiment, the first board material 31 is made of a medium density fiberboard having a density of 0.7 g / cm 3 The first board material 31 is made of a medium-density fiberboard having a thickness of 2.5 mm. As with the medium-density fiberboard constituting the surface material 30 of embodiment 1, the first board material 31 preferably contains an adhesive with excellent water resistance, and in embodiment 2, it is made of a medium-density fiberboard containing a urea-melamine co-condensation resin adhesive. The adhesive used for the medium-density fiberboard is not limited to a urea-melamine co-condensation resin adhesive, but may also contain diphenylmethane diisocyanate, phenolic resin, or the like. If a decorative sheet is attached to the outermost layer, a medium-density fiberboard containing an adhesive with low water resistance, such as urea resin, may also be used.

[0060] The second plate material 32 is made of a veneer having a thickness of about 1 to 6 mm. In the second embodiment, the second plate material 32 is made of a veneer having a thickness of 4 mm. Any wood species may be used for the veneer used as the second plate material 32, but it is preferable to use one having high bending properties (bending strength and bending Young's modulus).

[0061] Any adhesive may be used to bond the first and second plate members 31 and 32 together, but it is preferable to use a water-resistant adhesive. For example, vinyl acetate resin, aqueous vinyl urethane resin, urea melamine resin, melamine resin, phenol resin, resorcinol resin, urethane resin, epoxy resin, or acrylic resin adhesive may be used.

[0062] In the second embodiment, the two surface materials 30 are also bonded to the two frame materials 20 and the core material 10. Specifically, the upper surface material 30 is bonded with the first plate material 31 on the upper side (the surface side of the tread 2) and the second plate material 32 on the lower side, with the lower surface of the lower second plate material 32 bonded to the entire upper end surfaces of the two frame materials 20 and the entire upper surface of the upper paper 12 that forms the upper surface of the core material 10. The lower surface material 30 is bonded with the first plate material 31 on the lower side (the surface side of the tread 2) and the second plate material 32 on the upper side, with the upper surface of the upper second plate material 32 bonded to the entire lower end surfaces of the two frame materials 20 and the entire lower surface of the lower paper 12 that forms the lower surface of the core material 10. Any adhesive may be used to bond the two surface materials 30, 30 to the frame material 20 and core material 10, provided that it can bond the two together, but it is preferable to use a water-resistant adhesive. For example, the adhesive used to bond the first and second plate materials 31, 32 can be used.

[0063] As in the first embodiment, the tread board 2 is a sandwich panel in which a core material 10 consisting of a core 11 with paper (sheet-like material) 12 attached to the top and bottom surfaces is sandwiched between two surface materials 30, 30 and bonded together with a water-resistant adhesive. In this way, the tread board 2 has a three-layer structure, and the core material 10 is composed of the core 11 and two sheets of paper 12, 12, which have a significantly lower density and are lighter than the medium-density fiberboard (first plate material 31) and veneer (second plate material 32) used in the surface material 30, making it possible to reduce the weight of the tread board 2.

[0064] In this embodiment 2, as shown in Figures 5 and 6, decorative material 5 such as a decorative sheet or veneer is attached to the exposed surfaces (upper surface, front surface and front end of the lower surface) of the treads 2 that are exposed after construction of the stairs S.

[0065] With the above-described configuration, the second embodiment can also achieve the same effects as the first embodiment.

[0066] Furthermore, in the first embodiment, the surface material 30 was made solely of medium-density fiberboard, which, among wood boards, has a relatively smooth surface and excellent water resistance (water repellency), making it suitable for use as an interior material. However, its bending performance (bending strength, bending Young's modulus) is inferior to that of veneer. Therefore, in the second embodiment, the surface material 30 is made of a composite material in which a first plate material 31 made of medium-density fiberboard and a second plate material 32 made of veneer are laminated and bonded together, and the first plate material 31 is fixed to the core material 10 and the frame material 20 so that it is positioned on the surface side of the tread 2. Therefore, the second embodiment can provide a tread 2 that has excellent decorative properties (surface smoothness), water resistance (water repellency), and bending performance.

[0067] Other Embodiments In the treads 2 of the first and second embodiments, the frames 20 are provided only on the front and rear sides of the core material 10, not on either the left or right side of the core material 10, but in the stair treads of the present invention, the frames 20 are provided not only on the front and rear sides of the core material 10, but also on the left and right sides, i.e., the core material 10 may be surrounded on all four sides by four frames 20, ..., 20. In the treads 2 with frames 20 provided on all four sides of the core material 10, the core material 10 is not exposed, so they can be used as treads 2 for open staircases that do not use stringers 1, 1, for example.

[0068] Furthermore, in the treads 2 of the first and second embodiments, the core 11 is made of paper for the core material 10, but the core 11 may be made of a material other than paper. For example, the core 11 may be made of resin or metal.

[0069] Furthermore, in the treads 2 of the first and second embodiments, paper 12, 12 is used as the sheet-like material attached to the upper and lower surfaces of the core 11 with an adhesive. However, the sheet-like material is not limited to paper 12, 12. For example, a resin sheet or a thin metal plate may be attached to the upper and lower surfaces of the core 11 as the sheet-like material. While any material may be used for the sheet-like material, it is preferable to use the same material as the core 11, as this allows for easy adhesion and eliminates the need for an adhesive to attach the sheet-like material to the core 11.

[0070] Furthermore, in the treads 2 of the first and second embodiments, the frame members 20, 20 are made of wooden rod-shaped members (square lumber), but the material of the frame members 20, 20 is not limited to these. The frame members 20, 20 may be made of resin square lumber or metal square lumber as long as they are strong enough to hold the nail-shaped members 4, 4 for fixing the riser 3.

[0071] Furthermore, in the tread board 2 of the first embodiment, the two surface materials 30, 30 are made of medium-density fiberboard, and in the tread board 2 of the second embodiment, the two surface materials 30, 30 are made of a composite material in which a first plate material 31 made of medium-density fiberboard and a second plate material 32 made of a single sheet are laminated and bonded together, but the materials for the two surface materials 30, 30 are not limited to those mentioned above. The two surface materials 30, 30 may be made of any material as long as its bending strength is equal to or greater than that of medium-density fiberboard, such as thin plywood or hardboard.

[0072] In the above-described first and second embodiments, an example was described in which a honeycomb core in which each hole 11a has a hexagonal cross-sectional shape was used as the core 11, but the cross-sectional shape of each hole 11a is not limited to a hexagon as long as the core 11 has a plurality of holes 11a, ..., 11a extending in the thickness direction and arranged adjacent to each other in a plan view. The cross-sectional shape of each hole 11a in the core 11 may be triangular, rectangular, trapezoidal, circular, corrugated, semicircular, or the like.

[0073] Furthermore, in the first and second embodiments, the treads 2 are applied to the staircase S consisting of a straight staircase, but the staircase S to which the treads 2 can be applied is not limited to a straight staircase. [Industrial Applicability]

[0074] The present invention is useful for stair treads and staircases equipped with the same. [Explanation of symbols]

[0075] 2 Treads (treads for stairs) 10 Core material 11 cores 11a hole 12 Paper (sheets) 20 Frame material 30 Surface material 31 First board material (medium density fiberboard) 32 Second board (single board) S stairs

Claims

1. A staircase tread comprising a core material made of a rectangular plate-like body, a frame material provided at least on the front and rear sides of the core material, and two surface materials fixed to the upper and lower end surfaces of the frame material, The core material has a rectangular plate-shaped core having a plurality of holes extending in the thickness direction of the core material, and two sheet-shaped materials adhered to the upper and lower surfaces of the core, the upper surface material is bonded to the upper end surface of the frame material and to the upper sheet-like material constituting the upper surface of the core material; The lower surface material is bonded to the lower end surface of the frame material and the lower sheet-like material that forms the lower surface of the core material. A stair tread characterized by:

2. 2. The stair tread of claim 1, The frame material is provided only on the front and rear sides of the core material. A stair tread characterized by:

3. The stair tread according to claim 1 or 2, The core is made of paper. A stair tread characterized by:

4. 4. The stair tread according to claim 3, The sheet-like material is paper. A stair tread characterized by:

5. The stair tread according to claim 1 or 2, The surface material is made of medium density fiberboard. A stair tread characterized by:

6. The stair tread according to claim 1 or 2, The surface material is made of a composite material in which a medium density fiberboard and a veneer are laminated and bonded, and the medium density fiberboard is fixed to the core material and the frame material so that it is positioned on the surface side of the stair tread. A stair tread characterized by:

7. A staircase having a plurality of stair treads, The stair tread is the stair tread according to claim 1 or 2. A staircase characterized by:

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