Patent Publication Number: US-2016220036-A1

Title: Chair

Description:
TECHNICAL FIELD 
     The present invention relates to a chair in which an attachment part of an upholstery material of a load-supporting body, such as a seat body or a backrest, is improved. 
     Priority is claimed on Japanese Patent Application No. 2013-190952, filed Sep. 13, 2013, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     In seat bodies of chairs used for office work, generally, a cushion material, such as urethane, is arranged at an upper part of a base plate constituting a framework, and is covered with a sheet-like upholstery material from an outside surface of the cushion material to an outside edge of the base plate. 
     When the upholstery material of this type of chair is attached, it is easy to replace the upholstery material with another at the time of fouling or the like, and it is easy to apply stable tension throughout the upholstery material. Therefore, a technique of narrowing a peripheral edge of the upholstery material on a lower surface side of the base plate using a tightening cord, thereby fixing the upholstery material to the cushion material and the base plate is frequently used (for example, refer to Patent Documents 1 and 2). 
     In the chair described in Patent Documents 1 and 2, a bag-shaped insertion hole is provided in the peripheral edge of the upholstery material that holds the outside surface of the cushion material, and the outer peripheral edge of a base plate, the tightening cord is inserted through the insertion hole, and end parts of the tightening cord are tied together on the lower surface side of the base plate. A locking projection that restricts the displacement of the tightening cord to a base plate center side is provided on a lower surface side of such a chair, and thereby, positional deviation of the upholstery material is prevented. 
     In such a chair, the upholstery material can be easily attached to the cushion material and the base plate by tightening the tightening cord in the shape of a loop on the lower surface side of the base plate and tying the end parts. Moreover, variations in the tension that acts on the upholstery material can be reduced by managing the length of the tied part of the tightening cord. 
     CITATION LIST 
     Patent Document 
     [Patent Document 1] Japanese Patent Publication No. 3728576 
     [Patent Document 2] Japanese Patent Publication No. 4255670 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the chair described in Patent Documents 1 and 2, the locking projection is formed only in a direction in which the tightening cord that tends to narrow inward is caught. However, actually, if the upholstery material is stretched on the cushion material and the base plate, it becomes clear that the peripheral edge of the upholstery material tightened by the tightening cord is displaced not only in a direction in which the peripheral edge tends to narrow inward but also in a direction in which the peripheral edge tends to widen outward. 
     As the cause of this, for example, if the peripheral edge of the upholstery material is tightened by the tightening cord in a case where the base plate and the cushion material have a substantially rectangular shape in plan view, parts corresponding to vicinities of corner parts of the base plate or the cushion material on the peripheral edge of the upholstery material are most strongly pulled by the tightening cord. However, by the parts corresponding to vicinities of linear parts between the corner parts adjacent to each other on the peripheral edge of the upholstery material, pulling force becomes relatively weak. Therefore, it is predicted that the parts are displaced to partially widen outward due to the tension of the upholstery material. 
     Thus, an object of the invention is to provide a chair that can appropriately restrict displacement of a tightening cord and a peripheral edge of an upholstery material and can reduce positional deviation of an upholstery material. 
     Solution to Problem 
     In order to solve the above problems, a chair related to the invention includes a load-supporting body. The load-supporting body includes a base plate constituting a framework; a cushion material arranged on a front surface side of the base plate; an upholstery material stretched to cover at least an outside surface of the cushion material and an outer peripheral edge of the base plate; and a tightening cord inserted through a peripheral edge of the upholstery material and tightened to allow end parts to be tied together on a rear surface side of the base plate in a state in which the upholstery material has covered the outside surface of the cushion material and the outer peripheral edge of the base plate. The base plate is provided with first locking means for restricting displacement of the tightened tightening cord in a base-plate center direction, and second locking means for restricting displacement of the tightened tightening cord in a base plate outward direction. 
     Accordingly, if the tightening cord inserted through the peripheral edge of the upholstery material is tightened on the rear surface side of the base plate in a state in which the upholstery material has covered the outside surface of the cushion material and the outer peripheral edge of the base plate, the displacement of the tightening cord in the base-plate center direction is restricted by the first locking means, and the displacement of the tightening cord in the base plate outward direction is restricted by the second locking means. Therefore, not only the displacement of the peripheral edge of the upholstery material that tends to narrow inward but also the displacement thereof that tends to widen outward is restricted. 
     The base plate may be formed in a substantially rectangular shape having corner parts at four corners and linear parts between the corner parts, the corner parts may be provided with the first locking means, and at least some of the linear parts may be provided with the second locking means. 
     In this case, if the tightening cord inserted through the peripheral edge of the upholstery material is tightened on the rear surface side of the base plate in a state in which the upholstery material has covered the outside surface of the cushion material and the outer peripheral edge of the base plate, the tightening cord tends to be displaced in the direction of narrowing inward in the corner parts of the base plate, and the upholstery material tends to be displaced in the direction of widening outward in some of the linear parts of the base plate. In this case, each displacement of the tightening cord is restricted by the first locking means and the second locking means. Therefore, in every part of the base plate, curling of the upholstery material can be appropriately prevented. 
     The first locking means may include a first side wall protruding from a rear surface of the base plate to a rear side, and a first protruding wall protruding in an outward direction of the base plate from the vicinity of a protruding end of the first side wall, and the second locking means may include a second side wall protruding from the rear surface of the base plate to the rear side, and a second protruding wall protruding in an inward direction of the base plate from the vicinity of a protruding end of the second side wall. 
     In this case, slip-out of the tightening cord or the peripheral edge of the upholstery material is reliably restricted by the first protruding wall and the second protruding wall. Additionally, even in a case where the tightening cord or the peripheral edge of the upholstery material directly abuts against neither the first protruding wall nor the second protruding wall, the displacement of the tightening cord or the upholstery material is restricted by the first side wall or the second side wall. 
     A recessed groove that is continuous in a circumferential direction of the base plate may be formed in the rear surface of the base plate, the first side wall may be an inside wall of the recessed groove, and the second side wall may be an outside wall of the recessed groove. 
     In this case, when the upholstery material is attached, the tightening cord or the peripheral edge of the upholstery material can be arranged inside the first protruding wall or the second protruding wall, pushing the tightening cord or the peripheral edge of the upholstery material into the recessed groove that is continuous in the peripheral direction of the base plate. Therefore, the upholstery material can be easily attached. Additionally, since the tightening cord or the peripheral edge of the upholstery material is arranged within the recessed groove that is continuous in the circumferential direction of the base plate, the upholstery material is not more easily curled. 
     It is desirable that the first protruding wall and the second protruding wall be arranged so as to be separated from each other in a direction in which the tightening cord extends, and to be adjacent to each other. 
     In this case, even if the length of the first protruding wall and the second protruding wall is extended, the tip parts of the first protruding wall and the second protruding wall are stopped from coming into contact with each other. For this reason, the length of the first protruding wall and the second protruding wall can be sufficiently extended, and when the tightening cord or the peripheral edge of the upholstery material is attached, the first protruding wall and the second protruding wall can be easily bent and deformed. Therefore, this can facilitate the attachment of the upholstery material. 
     It is preferable that respective tip parts of the first protruding wall and the second protruding wall that are provided adjacent to each other extend to positions with substantially half lengths of the separation width of the first side wall and the second side wall in a direction intersecting the direction in which the tightening cord extends. 
     In this case, since the wide range, in a slip-out direction, of a region where the peripheral edge of the upholstery material and the tightening cord are arranged is covered with the first protruding wall and the second protruding wall, slip-out of the peripheral edge of the upholstery material can be effectively prevented. Additionally, the work of putting the upholstery material between the first side wall and the second side wall is not easily hindered by the first protruding wall and the second protruding wall. 
     Tip parts of the first protruding wall and the second protruding wall may be arranged at positions that face each other. 
     In this case, since the tip parts of the first protruding wall and the second protruding wall are arranged to face each other, even if the displacement direction of the tightening cord or the peripheral edge of the upholstery material varies, the displacement of the tightening cord or the peripheral edge of the upholstery material is reliably restricted by any one of the first protruding wall and the second protruding wall. 
     Portions of tip parts of the first protruding wall and the second protruding wall may be arranged to face each other, and remaining portions thereof may be arranged so as to be separated from each other in a direction in which the tightening cord extends. 
     In this case, even if the displacement direction of the tightening cord or the peripheral edge of the upholstery material varies, the displacement of the tightening cord or the peripheral edge of the upholstery material is reliably restricted by any one of the first protruding wall and the second protruding wall. Additionally, since only the portions of the tip parts of the first protruding wall and the second protruding wall face each other, and the remaining portions thereof are separated from each other in the direction in which the tightening cord extends, the first protruding wall and the second protruding wall extend to be long along the direction in which the tightening cord extends. For this reason, the first protruding wall and the second protruding wall can be easily bent and deformed when the tightening cord or the peripheral edge of the upholstery material is attached. Therefore, this can facilitate the attachment of the upholstery material. 
     Advantageous Effects of Invention 
     According to the invention, since not only the displacement of the peripheral edge of the upholstery material that tends to narrow inward but also the displacement thereof that tends to widen outward can be appropriately restricted, positional deviation of the upholstery material can be more reliably suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view of a chair of a first embodiment of the invention. 
         FIG. 2  is a perspective view in a state in which a leg part of the chair of the first embodiment of the invention is removed. 
         FIG. 3  is a bottom view of a base plate of the first embodiment of the invention. 
         FIG. 4  is a perspective view when the base plate of the first embodiment of the invention is seen from a lower, diagonally front and left side. 
         FIG. 5  is an enlarged view of a V portion, in  FIG. 3 , of a seat body of the first embodiment of the invention. 
         FIG. 6  is a sectional view, corresponding to section VI-VI of  FIG. 3 , of the seat body of the first embodiment of the invention. 
         FIG. 7  is a sectional view, corresponding to section VII-VII of  FIG. 3 , of the seat body of the first embodiment of the invention. 
         FIG. 8  is a bottom view of main parts of a base plate of a second embodiment of the invention. 
         FIG. 9  is a bottom view of main parts of a base plate of a third embodiment of the invention. 
         FIG. 10  is a bottom view of main parts of a base plate of a fourth embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described with reference to the drawings. In addition, in the following description, a direction in which the front of a human being who sits down in a regular posture on a chair faces and which is indicated by arrow FR in the drawings is referred to as “front”, and a direction opposite to the front is referred to as “rear”. Additionally, as for “up”, “down”, “left”, and “right”, a direction indicated by arrow UP in the drawings on the upper side of the human being who sits down in the regular posture on the chair is referred to as “up”, and a direction opposite thereto is referred to as “down”, and a direction indicated by arrow LH in the drawings on the left of the human being who sits down in the regular posture on the chair  1  is referred to as “left”, and a direction opposite thereto is referred to as “right”. 
     First, a first embodiment illustrated in  FIGS. 1 to 7  will be described. 
       FIG. 1  is a side view illustrating the overall configuration of the chair  1  of this embodiment, and  FIG. 2  is a perspective view when the chair  1  from which some components are removed is seen obliquely from below. 
     As illustrated in these drawings, the chair  1  of this embodiment includes a leg part  2  placed on a floor F, a box-like supporting base  3  installed at an upper end of the leg part  2 , a seat body  4  on which a sitting person sits down, a seat-receiving member  5  attached to an upper surface of the supporting base  3  to support the seat body  4 , and a backrest part  6  that extends to a rear part upper side from the supporting base  3  and supports the back of a sitting person who sits down on the seat body  4 . 
     The leg part  2  includes a multi-branch leg  7  with casters  7   a,  and a leg pillar  8  that is erected from a central part of the multi-branch leg  7  and incorporates a gas spring that is a lifting mechanism, and the supporting base  3  is attached to an upper end part of the leg pillar  8  so as to be rotatable in a horizontal direction. A lift-adjusting mechanism of the leg pillar  8  and a tilt-adjusting mechanism of the backrest part  6  are incorporated into the supporting base  3 . The backrest part  6  includes a backrest-supporting frame  9  having a substantially L-shape in a side view, and a backrest body  10  that is attached to a front surface of a rear upper part of the backrest-supporting frame  9  and directly supports the back of a sitting person who sits down on the seat body  4 , and a front lower end of the backrest-supporting frame  9  is coupled to the tilt-adjusting mechanism within the supporting base  3 . 
     In addition, reference signs  11  in  FIGS. 1 and 2  designate a pivotal shaft of the backrest-supporting frame  9  on the supporting base  3 , and reference sign  12  designates an operation knob of the tilt-adjusting mechanism provided to protrude from a side surface of the supporting base  3 . Additionally reference sign  90  in  FIG. 1  designates armrests attached to lower surfaces on both left and right sides of the seat body  4  as additional parts. 
       FIG. 3  is a bottom view of the seat body  4 . In this embodiment, the seat body  4  constitutes a load-supporting body of the chair  1  of this embodiment. 
     The seat body  4  includes a base plate  13  constituting a framework, a cushion material  14  made of urethane attached to an upper part of the base plate  13 , and an upholstery material  15  that is stretched to cover an outside surface of the cushion material  14  to an outer peripheral edge of the base plate  13 . In addition, in  FIG. 3 , the upholstery material  15  is illustrated by phantom lines for the sake of illustration. 
       FIG. 4  is a perspective view when the base plate  13  is seen obliquely from below. 
     The base plate  13  is formed of synthetic resin having elasticity, and is formed in a substantially oblong shape with four rounded corners in a top view. That is, the base plate  13  is provided with corner parts  13   a  that are rounded at four corners, and has an external shape in which linear parts  13   b  are respectively arranged between the corner parts  13   a  adjacent to each other. The base plate  13  is provided such that a continuous shielding wall  16  serving as a reinforcing rib protrudes downward from a lower surface of a peripheral edge excluding a central region of a rear side. The shielding wall  16  conceals that a lower surface of the base plate  13  is seen from a side, and functions to restrict excessive bending deformation of the whole region of the base plate  13 . Additionally a plurality of reinforcing ribs  23  with low protruding height extending in a forward-rearward direction are provided at equal intervals so as to protrude from a region closer to an inner side than the shielding wall  16  of the lower surface of the base plate  13 . 
     The base plate  13  is held by the seat-receiving member  5  fixed on the supporting base  3  so as to be slidable forward and backward. 
     As illustrated in  FIG. 2 , a locking lever  21  for locking the front and rear positions of the seat body  4  is tiltably attached to a left side part of the base plate  13 . A plurality of lock holes  35  are formed in the seat-receiving member  5 , and the sliding position of the base plate  13  is locked by a tip part of the locking lever  21  being fitted into an arbitrary lock hole  35 . A release operation knob  22  to be gripped by an operator is integrally formed on a base end side in the locking lever  21 . 
       FIG. 5  is an enlarged view illustrating a V portion of  FIG. 3 , and  FIGS. 6 and 7  are views illustrating sections corresponding to a VI-VI section and a VII-VII section of  FIG. 3 . 
     A bag-shaped insertion hole part  17  running along a circumferential direction is provided at a peripheral edge  15   a  of the upholstery material  15  that is arranged so as to be routed to a lower surface side of the peripheral edge of the base plate  13 . The insertion hole part  17  is broken at a portion of the peripheral edge  15   a  of the upholstery material  15  in the circumferential direction, and a tightening cord  18  is inserted from the broken portion of the tightening cord  18 . The tightening cord  18  tightens the peripheral edge  15   a  of the upholstery material  15  on the lower surface side of the base plate  13 , in a state in which the upholstery material  15  is stretched to hold the outside surface of the cushion material  14  to the outer peripheral edge of the base plate  13 , and both end parts  18   a  and  18   a  are tied together with a predetermined tension in that state. 
     Here, a recessed groove  19  running along the circumferential direction is formed in the lower surface of the outer peripheral edge of the base plate  13 , and the peripheral edge  15   a  of the upholstery material  15  is fitted into the recessed groove  19  together with the tightening cord  18 . 
     The recessed groove  19  is formed by a first annular side wall  24  that protrudes downward from the lower surface of the base plate  13 , and a second annular side wall  25  that protrudes downward from the lower surface of the base plate  13  at a position separated to the outside of the first side wall  24 . In this embodiment, a portion of the first side wall  24  is formed continuously with a root side of the shielding wall  16 . In other words, the shielding wall  16  is formed continuously with a protruding end of the first side wall  24 . 
     A plurality of first protruding walls  26  that protrude in an outward direction of the base plate  13  from the vicinity of the protruding end of the first side wall  24  are provided in regions corresponding to the respective corner parts  13   a  of the base plate  13  of the first side wall  24 , and regions corresponding to the linear parts  13   b.  Meanwhile, a plurality of second protruding walls  27  that protrude in an inward direction of the base plate  13  from the vicinity of a protruding end of the second side wall  25  are provided in regions corresponding to the linear parts  13   b  on both left and right sides of the base plate  13  and the linear part  13   b  on the front side thereof, in the second side wall  25 . 
     In this embodiment, the first side wall  24  and the first protruding wall  26  constitute first locking means for restricting the displacement of the tightened tightening cord  18  in a base-plate center direction, and the second side wall  25  and the second protruding wall  27  constitute second locking means for restricting the displacement of the tightened tightening cord  18  in the outward direction of the base plate. 
     The first protruding wall  26  and the second protruding wall  27  provided in the regions corresponding to the linear parts  13   b  on both left and right sides and the linear part  13   b  on the front side are arranged so as to be separated from each other by a predetermined distance in a direction in which (the tightening cord  18  of) the recessed groove  19  extends, and to be adjacent to each other. That is, the first protruding wall  26  and the second protruding wall  27  are alternately arranged with the recessed groove  19  interposed therebetween. 
     Regarding the first protruding wall  26  and the second protruding wall  27  that are provided to be adjacent to each other in the regions corresponding to the linear parts  13   b  on both left and right sides and the linear part  13   b  on the front side, as illustrated in  FIG. 5 , their respective tip parts extend to positions with substantially half lengths of the groove width of the recessed groove  19 . 
     In the chair  1  of this embodiment, in a case where the cushion material  14  is arranged on the base plate  13  and the upholstery material  15  is attached thereto, first, the upholstery material  15  is covered to hold the outside surface of the cushion material  14  and the outer peripheral edge of the base plate  13 , and the peripheral edge  15   a  of the upholstery material  15  is fitted into the recessed groove  19  of the base plate  13  together with the tightening cord  18  on the lower surface side of the base plate  13 . In this case, in the respective corner parts  13   a  and the linear part  13   b  on a rear side, the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  ride over only the first protruding wall  26  and are pushed into the recessed groove  19 . Meanwhile, in the linear parts  13   b  on both left and right sides and the linear part  13   b  on the front side, the first protruding wall  26  and the second protruding wall  27  ride over the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  and are pushed into the recessed groove  19 . 
     Next, in this state, both end parts of the tightening cord  18  pulled out from the insertion hole part  17  of the peripheral edge of the upholstery material  15  are tightened using an appropriate instrument, and both the end parts of the tightening cord  18  are tied together in that state. In addition, the tightening of the tightening cord  18  can also be manually performed by a worker. In this way, if both the end parts of the tightening cord  18  are tightened, the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  tend to be displaced in a base-material center direction in the regions corresponding to the respective corner parts  13   a  of the base plate  13  and the rear linear part  13   b,  and the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  tend to be displaced in a base material outward direction in some of the regions corresponding to the linear parts  13   b  on both the left and right sides of the base plate  13  and the linear part  13   b  on the front side, and tend to be displaced in the base-material center direction in some of the other above regions. In this case, the displacement, in the base-plate center direction, of the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  is restricted by the first side wall  24  and the first protruding wall  26 , and the displacement, in the base plate outward direction, of the tightening cord  18  and the peripheral edge  15   a  of the upholstery material  15  is restricted by the second side wall  25  and the second protruding wall  27 . 
     As described above, in the chair  1  related to this embodiment, the second side wall  25  and the second protruding wall  27  that are the second locking means in addition to the first side wall  24  and the first protruding wall  26  that are the first locking means are provided at suitable positions on the lower surface of the base plate  13  of the seat body  4 . Therefore, not only the displacement of the peripheral edge  15   a  of the upholstery material  15  that tends to narrow inward but also the displacement thereof that tends to widen outward can be appropriately restricted. For this reason, curling of the upholstery material  15  in various directions can be more reliably suppressed. 
     Particularly, in the chair  1  related to this embodiment, the second side wall  25  and the second protruding wall  27  are provided in the linear parts  13   b  on both the left and right sides of the base plate  13  and the linear part  13   b  on the front side in the thick cushion material  14  superimposed on an upper surface. Therefore, the displacement of the peripheral edge  15   a  of the upholstery material  15  that tends to widen outward accompanying the tightening of the tightening cord  18  can be appropriately restricted. 
     Additionally, in the chair  1  related to this embodiment, the first locking means is constituted of the first side wall  24  and the first protruding wall  26 , and the second locking means is constituted of the second side wall  25  and the second protruding wall  27 . Therefore, slip-out of the peripheral edge  15   a  of the upholstery material  15  from the recessed groove  19  can be reliably restricted by the first protruding wall  26  and the second protruding wall  27 . In addition, even in a case where the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  directly abuts against neither the first protruding wall  26  nor the second protruding wall  27 , the displacement of the tightening cord  18  or the upholstery material  15  can be restricted by the first side wall  24  and the second side wall  25  that are walls of the recessed groove  19 . 
     Moreover, in the chair  1  related to this embodiment, the recessed groove  19  is provided in the lower surface of the base plate  13  so as to be continuous in the circumferential direction of the base plate  13 , the first side wall  24  is constituted of an inside wall of the recessed groove  19 , and the second side wall  25  is constituted of an outside wall of the recessed groove  19 . Therefore, when the upholstery material  15  is attached, the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  can be easily arranged inside the first protruding wall  26  or the second protruding wall  27 , continuously pushing the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  into the recessed groove  19  on the base plate  13 . For this reason, the upholstery material  15  can be easily attached. Moreover, since the displacement of the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  is restricted within the continuous recessed groove  19 , the curling of the upholstery material  15  can be made less likely to occur. 
     However, the continuous recessed groove  19  may not necessarily be formed in the lower surface of the base plate  13 . As in a second embodiment illustrated in  FIG. 8 , the first side wall  124  and the second side wall  125  that are narrow may intermittently protrude from the lower surface of the base plate  113  so as to run along the direction in which the tightening cord  18  extends, and the first protruding wall  126  and the second protruding wall  127  may be respectively provided continuously with the vicinities of the respective protruding ends of the first side wall  124  and the second side wall  125 . 
     Additionally, in the chair  1  related to this embodiment, the first protruding wall  26  and the second protruding wall  27  provided in the linear parts  13   b  are arranged so as to be separated from each other in the direction in which the tightening cord  18  extends, and to be adjacent to each other. Therefore, the length of the first protruding wall  26  and the second protruding wall  27  can be sufficiently extended without causing any contact between tip parts of the first protruding wall  26  and the second protruding wall  27 . For this reason, the first protruding wall  26  and the second protruding wall  27  can be easily bent and deformed when the tightening cord  18  or the peripheral edge of the upholstery material  15  is attached. Therefore, this can facilitate the attachment of the upholstery material  15 . 
     Particularly, in the case of this embodiment, the respective tip parts of the first protruding wall  26  and the second protruding wall  27  that are provided adjacent to each other in the linear parts extend to positions with substantially half lengths of the groove width (the separation width of the first side wall  24  and the second side wall  25 ) of the recessed groove  19 . Therefore, the wide range of the recessed groove  19  is blocked by the first protruding wall  26  and the second protruding wall  27 , and the slip-out of the peripheral edge  15   a  (tightening cord  18 ) of the upholstery material  15  from the inside of the recessed groove  19  can be effectively prevented. Additionally, as in this embodiment, even in a case where the respective tip parts of the first protruding wall  26  and the second protruding wall  27  are extended to the positions with substantially half lengths of the groove width of the recessed groove  19 , if minimal setting is made so that the tightening cord  18  can pass through the recessed groove at least, the work of putting the peripheral edge  15   a  of the upholstery material  15  into the recessed groove  19  is not hindered by the first protruding wall  26  and the second protruding wall  27 . 
       FIG. 9  is a view illustrating lower surfaces of main parts of a base plate  213  of a third embodiment of the invention. 
     In this embodiment, tip parts of a first protruding wall  226  and a second protruding wall  227  provided in the linear parts are arranged at positions that face each other. 
     In the case of this embodiment, the tip parts of the first protruding wall  226  and the second protruding wall  227  are arranged to face each other. Therefore, even if the displacement direction of the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  varies, the displacement of the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  can be reliably restricted by any one of the first protruding wall  226  and the second protruding wall  227 . 
       FIG. 10  is a view illustrating lower surfaces of main parts of a base plate  313  of a fourth embodiment of the invention. 
     In this embodiment, portions of tip parts of a first protruding wall  326  and a second protruding wall  327  provided in the linear parts face each other, and remaining portions thereof are arranged so as to be separated from each other in a direction in which the tightening cord  18  extends. 
     In this embodiment, even if the displacement direction of the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  varies, the displacement of the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  can be reliably restricted by any one of the first protruding wall  326  and the second protruding wall  327 . 
     Additionally, since only the portions of the tip parts of the first protruding wall  326  and the second protruding wall  327  face each other, and remaining portions thereof are separated from each other in the direction in which the tightening cord  18  extends, the first protruding wall  326  and the second protruding wall  327  extend to be long along the direction in which the tightening cord  18  extends. For this reason, the first protruding wall  326  and the second protruding wall  327  can be easily bent and deformed when the tightening cord  18  or the peripheral edge  15   a  of the upholstery material  15  is attached. For this reason, the attachment of the upholstery material  15  can be facilitated. 
     The invention is not restricted to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, although the above embodiments exemplify a load-supporting body as a seat body, it is also possible to adopt the same structure for a backrest body of the backrest part. 
     Industrial Applicability 
     According to the chair of the invention, since not only the displacement of the peripheral edge of the upholstery material that tends to narrow inward but also the displacement thereof that tends to widen outward can be appropriately restricted, positional deviation of the upholstery material can be more reliably suppressed. 
     REFERENCE SIGNS LIST 
     
         
           1 : CHAIR 
           4 : SEAT BODY (LOAD-SUPPORTING BODY) 
           13 ,  113 ,  213 ,  313 : BASE PLATE 
           14 : CUSHION MATERIAL 
           15 : UPHOLSTERY MATERIAL 
           18 : TIGHTENING CORD 
           19 : RECESSED GROOVE 
           24 ,  124 : FIRST SIDE WALL 
           25 ,  125 : SECOND SIDE WALL 
           26 ,  126 ,  226 ,  326 : FIRST PROTRUDING WALL 
           27 ,  127 ,  227 ,  327 : SECOND PROTRUDING WALL