Bar stool

Description

[0001] The utility model relates to the furniture industry, in particular to the design of bar stools (stools) intended for use in catering establishments (bars, restaurants) or at home at bar counters and high kitchen islands.

[0002] The stool patented by RU 2572449 was chosen as the prototype. Its essence lies in the fact that structural rigidity is achieved by connecting flat L-shaped legs directly at the top using interlocking cutouts, without the use of additional connecting elements. The disadvantage of this solution is that the connecting joint is located under the seat and does not provide support for the user's feet. It also places increased demands on the precision of the complex interlocking joints. The claimed utility model, however, addresses the issue of increasing frame rigidity by using a separate ring element that also serves as a footrest.

[0003] The objective of this utility model is to create a bar stool with increased rigidity and structural stability, technologically advanced sheet material manufacturing, and an integrated, reliable footrest.

[0004] The technical result achieved by using the utility model is to increase the strength and rigidity of the stool frame.

[0005] The technical result is achieved due to the fact that the bar stool contains a seat and a supporting structure including four L-shaped legs, each of which has an upper horizontal section for fastening the seat and a lower vertical section, the legs are made of sheet material, mainly multilayer plywood, while in the lower part of each vertical section of the legs there are blind grooves in which an annular connecting element is placed, made of the same sheet material, embracing the legs from the inside of the structure and forming a closed contour, and the annular connecting element is fixed in said grooves with the possibility of performing the function of additional support for the user's feet, while the upper end of the horizontal section of each leg adjoins the lower surface of the seat and is secured to it by means of more than two fastening elements.

[0006] The legs and ring connector are made of birch plywood with a thickness of 15-30 mm.

[0007] The ring connecting element is made of the same sheet material as the seat, and the inner contour of the ring connecting element is formed by the outer contour of the seat.

[0008] The ring connecting element is made in the form of an annular strip cut along the perimeter of the seat with a given wall thickness.

[0009] The presence of four L-shaped legs provides a stable four-point support, but it is the L-shaped shape of each element that allows the load from the seat to be redistributed onto the vertical posts in such a way that the occurrence of torques in the fastening points is minimized, which directly contributes to increasing the strength and rigidity of the stool frame by eliminating fragile right angles in the area where the seat and leg connect.

[0010] The leg's design features an upper horizontal section, which bears the entire load from the seat, and a lower vertical section, which transfers the load to the floor, creating a single piece that functions as a lever. This monolithic design eliminates the weak connecting seam at the most stressed point, significantly increasing the strength and rigidity of the stool frame compared to composite legs.

[0011] The use of multilayer plywood for the legs ensures high geometric stability under load due to the cross-grain arrangement of the layers. This material's ability to resist warping and delamination under alternating loads (when a person sits and stands up) contributes to the increased strength and rigidity of the stool frame throughout its entire service life.

[0012] By creating blind grooves in the legs and inserting a ring-shaped connecting element within them, which encircles the legs from the inside and forms a closed loop, the four individual legs are transformed into a single spatial truss. The ring-shaped element acts as a spacer, locking the legs at a predetermined distance and preventing them from "sliding apart" under load. This dramatically increases the strength and rigidity of the stool frame, as the structure no longer functions as a parallelogram and is susceptible to folding.

[0013] The ring element's fixation in the grooves creates a permanent tongue-and-groove connection that withstands both shear and shear loads, supporting horizontal loads. The fact that this element also serves as a footrest means that any pressure from the user's feet further wedges the structure, increasing friction at the joints, further enhancing the strength and rigidity of the stool frame during dynamic use.

[0014] Securing the upper end of the horizontal leg section to the lower surface of the seat using more than two fasteners prevents the leg from rotating relative to the seat. This flange connection, with three or more fixing points, ensures the assembly remains immobile under shear loads, guaranteeing increased strength and rigidity of the stool frame at the crucial seat-to-support connection.

[0015] The use of birch plywood with a thickness of 15 to 30 mm for all load-bearing elements (legs and ring) ensures an optimal balance between section modulus and structural weight. Thicknesses less than 15 mm would result in deflection, while thicknesses greater than 30 mm would result in excessive weight without significantly increasing load-bearing capacity. Choosing this range maximizes the strength and rigidity of the stool frame while using the material efficiently.

[0016] To ensure perfect geometric alignment of the components and the chair's strength and stability by optimizing the spatial layout of the supporting elements, the ring-shaped connecting element is made from the same plywood sheet as the seat. The manufacturing process includes a preliminary seat cutting step, after which the resulting outer contour of the seat is used as the inner contour of the ring-shaped connecting element. In other words, the ring-shaped connecting element is cut along the outer contour of the seat with a specified wall thickness, forming a closed annular strip of material. This manufacturing technique ensures, firstly, that the shape of the connecting element precisely matches the shape of the seat and leg assembly, and secondly, optimizes the consumption of expensive sheet material (birch plywood) through low-waste production (nested cutting).

[0017] The ring-shaped connecting element is crafted from the same plywood sheet as the seat, cut along its outer contour. This design ensures increased strength and stability of the stool by optimizing the spatial layout of the supporting elements. This design ensures identical physical and mechanical properties of the mating parts, eliminating internal stress during operation; highly accurate leg positioning is guaranteed, preventing them from warping; and the solid, closed ring effectively acts as a rigid spatial strut, evenly distributing loads and preventing frame deformation.

[0018] The ring-shaped connecting element is made from the same plywood sheet as the seat, and its inner contour is formed along the outer contour of the seat, increasing the strength and rigidity of the stool frame due to the following factors: the physical and mechanical properties (modulus of elasticity, coefficients of temperature and humidity expansion) of the seat and the ring are identical, which eliminates the occurrence of internal stresses in the connecting nodes during operation; the precise accuracy of the relative positioning of the legs is guaranteed due to the reference geometry of the closed contour, which prevents distortions and ensures the stability of the structure; the solid-cut ring, without joints, acts as a monolithic spatial strut, evenly redistributing tensile and compressive forces between the legs and effectively resisting frame deformations under dynamic loads.

[0019] The utility model is illustrated by the following figures:

[0020] Fig. 1 - general view of a bar stool;

[0021] Fig. 2 - bottom view of the bar stool;

[0022] The bar stool is prefabricated and manufactured using standard wood processing equipment.

[0023] The first stage of production involves preparing the raw materials. Birch plywood sheets are used to create the legs and ring connector. Birch plywood was chosen for its high strength properties, multi-layer structure, resistance to deformation, and ability to withstand significant alternating loads.

[0024] The optimal plywood thickness is between 15 and 30 mm. The preferred design uses 20 mm plywood for the legs and 15 mm for the connecting element. This thickness is a compromise solution, ensuring the necessary rigidity of the vertical posts and horizontal sections, while also maintaining an acceptable weight for the finished product and ease of processing.

[0025] Four identical legs are cut from a sheet of plywood. Cutting is done using high-precision CNC milling or laser cutting. These methods ensure clean cuts and precise geometric dimensions, which are critical for subsequent assembly.

[0026] Each leg has an L-shape, which is structurally divided into two functional sections:

[0027] 1. The upper horizontal section, which is designed to support and secure the seat. This section is a platform, the width and length of which are designed to accommodate at least two fasteners. It is important that the upper edge of this section is finished and machined flush to ensure maximum contact with the seat.

[0028] 2. The lower vertical section serves as a support post. The length of this section determines the overall height of the stool (the standard height of a bar stool is 75-85 cm from the floor to the seat). The height of an unupholstered stool is preferably between 710 and 750 mm.

[0029] The lower vertical section is inclined relative to the vertical. In the lower third of each vertical section, at a strictly defined height from the bottom end of the leg (preferably 230-250 mm, which is ergonomically comfortable for placing feet), blind grooves are milled on the inside of the structure.

[0030] The groove width is equal to the thickness of the leg material. This precise fit is necessary to ensure a tight, tongue-and-groove fit without play.

[0031] The grooves are blind. They do not extend onto the outer (external) surface of the leg. This is done to preserve the aesthetic appearance of the product, as the ends of the ring element will not be visible from the outside, and to maintain the integrity of the outer plywood fibers, which positively affects the strength of the leg itself. A ring-shaped connecting element is cut parallel to the legs from the same 15 mm thick plywood sheet. It is a closed frame whose geometric shape (square, round, rectangular with rounded corners) follows the shape of the seat or design solution. Seat 6 can be made of various materials (plywood, solid wood, MDF) and can be upholstered. The bottom of the seat is marked with mounting locations corresponding to the positions of the horizontal sections of the legs.

[0032] The seat is placed on the assembled frame so that the upper end of each leg's horizontal section is flush with the lower surface of the seat. To ensure a secure connection, taking into account the cantilever load that occurs when the user sits on the edge of the seat or steps off the stool, the seat is secured with more than two fasteners.

[0033] This specific implementation example uses three or four wood screws (either confirmat or self-tapping) with countersunk heads per connection point. The fastener passes through the horizontal section of the leg from the bottom up and into the seat body. Three mounting points firmly secure the leg, preventing it from rotating relative to the seat, significantly increasing the durability and rigidity of the assembly.

[0034] When assembled, the stool forms a single, rigid system. The user's weight (static load) is transferred through the seat to the horizontal sections, then to the vertical sections of the legs, and to the floor. Dynamic loads (rocking, displacement) are absorbed and dampened by the ring-shaped connecting element, which, acting as a strut, evenly distributes the force across all four legs. The wide ring allows the user to intuitively place their feet on it, which not only increases comfort but also provides additional stabilization due to the weight of the sitter's legs.

[0035] Thus, the proposed design allows us to achieve the stated technical result: increasing the strength and rigidity of the stool frame by using a connecting element as a support for the legs, as well as ensuring high technological efficiency of manufacturing from sheet materials.

Claims

1. A bar stool comprising a seat and a support structure including four L-shaped legs, each of which has an upper horizontal section for fastening the seat and a lower vertical section, characterized in that the legs are made of multilayer plywood, while in the lower part of each vertical section of the legs there are blind grooves in which an annular connecting element is placed, made of the same sheet material, embracing the legs from the inside of the structure and forming a closed contour, and the annular connecting element is fixed in said grooves with the possibility of performing the function of additional support for the user's feet, while the upper end of the horizontal section of each leg adjoins the lower surface of the seat and is fixed to it, and the legs and the annular connecting element are made of birch plywood with a thickness of 15-30 mm.

2. A bar stool according to paragraph 1, characterized in that the annular connecting element is made in the form of an annular strip cut along the perimeter of the seat with a given wall thickness.

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