ladder

Abstract

To provide a ladder having excellent connection stability between support frame bodies.SOLUTION: A ladder 1 includes a pair of supports 4 and a plurality of rungs 5. The support 4 includes a plurality of support frame bodies 7, and a connector 8 that connects end parts 7e of the support frame body 7 so as to abut each other. The support frame body 7 includes a support lateral plate 7S constituting a lateral face of the support 4, and a pair of support end plates 7T vertically formed on one side of a longitudinal direction along a long edge part 7c of the support lateral plate 7S. The connector 8 includes: a first fixing plate 15 arranged on a face 7b on a support end plate 7T side of the support lateral plate 7S, straddling the end parts 7e; a second fixing plate 16 arranged on a face 7a opposite the support end plate 7T of the support lateral plate 7S, straddling the end parts 7e; and fixing members 17, 18 that mutually connect and fix the first fixing plate 15 and the second fixing plate 16. The second fixing plate 16 is projected along an external edge part, and has an auxiliary rib 27 that is contacted and engaged with the long edge part 7c of the support lateral plate 7S from the outside in a longitudinal direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a ladder having stanchions that are configured by being divided in a longitudinal direction. [Background Art]

[0002] Among long ladders for high-place work, in consideration of transportability and storability, there is known a ladder in which left and right stanchions supporting rungs are configured by being divided in a longitudinal direction, ends of the stanchions are butted against each other and connected by a connecting member (for example, Patent Document 1).

[0003] In the ladder disclosed in Patent Document 1, each stanchion is a frame body having a substantially U-shaped cross section, and includes a back plate and a pair of side plates that are continuous with both side edges of the back plate and are erected perpendicularly to the back plate. On the other hand, the connecting member is a plate material having a substantially U-shaped cross section that is slightly smaller than the stanchion, and includes a connecting back plate disposed opposite to the back plate of the stanchion, and a pair of connecting side plates that are continuous with both side edges of the connecting back plate and disposed opposite to the side plates of the stanchion. Further, the connecting back plate is formed in a curved shape convex toward the back plate side of the stanchion, and by fastening bolts and nuts from both sides in the plate surface direction to deform the connecting back plate into a linear shape, the outer surface of the connecting side plate is brought into face-to-face contact with the inner surface of the side plate of the stanchion. This suppresses displacement and bending between the stanchions. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2021-71001 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, in the column connection structure of Patent Document 1, depending on the increase in warping or distortion of the column side plates and the rigidity of the connecting members, even when the bolts and nuts are tightened, the connecting side plates do not properly contact the column side plates, and the misalignment, bending, and rattling of the columns cannot be sufficiently suppressed. Moreover, in this structure, bolts and nuts must be placed on both sides of the connecting back plate in order to deform the connecting back plate into a straight shape, which makes the installation and removal of the connecting members more time-consuming.

[0006] This invention was made in view of the above-mentioned problems, and aims to provide a ladder with excellent stability in the connection of the support columns and ease of assembly. [Means for solving the problem]

[0007] To solve the above problems, the ladder of the present invention employs the following technical means.

[0008] The ladder of the present invention comprises a pair of left and right support columns extending vertically and arranged side by side at a predetermined interval in the left-right direction, and a plurality of rungs horizontally between the support columns, wherein each support column has a plurality of support column frames and a connector that connects the ends of the support column frames in a butted state, and each support column frame has a support column side plate that constitutes the side surface of the support column, and a pair of support column end plates that are formed to stand upright from the long edges of both long edges of the support column side plate in one direction to the left, and the connector has a first fixing plate that is arranged across the ends and face-to-face with the surface of the support column side plate on the side of the support column end plate, a second fixing plate that is arranged across the ends and face-to-face with the surface of the support column side plate opposite to the support column end plate, and a fixing member that connects and fixes the first fixing plate and the second fixing plate to each other. In the aforementioned ladder, the side on which the user ascends and descends is the rear side, and the opposite side is the front side. The second fixing plate is, Of the front and rear outer edges of the second fixing plate, the front Along the outer edge Rib-like projections are formed, extending in one direction (left or right) from the outer edge. The side plate of the support column Front Long edge corner department along the front of the long corner portion It has auxiliary ribs that are abutted and engaged from the outside.

[0010] The auxiliary rib may be formed so that the front-to-back width of its base end is greater than the front-to-back width of its tip end.

[0011] The fixing member has a connecting shaft that is inserted through the first fixing plate and the second fixing plate from the direction of the plate surface, and one of the first support frame members of the support frame members may be formed to extend vertically from the end face on the shorter side of the support side plate and have a connecting slit through which the connecting shaft is inserted when the first support frame member is connected to the other second support frame member.

[0012] The connecting slit may have a guide portion through which the connecting shaft is inserted when the first support frame is connected to the second support frame with the first support frame offset in one direction in the front-rear direction, and a engage portion that extends from the guide portion in one direction in the front-rear direction, and through which the connecting shaft is inserted and engaged when the first support frame and the second support frame are connected in a straight line. [Effects of the Invention]

[0013] According to the ladder of the present invention, the support column frames can be securely connected and fixed to each other regardless of warping or distortion of the support column end plates, thereby dramatically improving the connection stability of the support columns. Moreover, since the connecting device is positioned and held relative to the support column frame by engaging the auxiliary ribs of the second fixing plate with the long edges of the support column side plates, the number of fixing members that need to be placed can be reduced accordingly. Therefore, assembly workability is also dramatically improved. [Brief explanation of the drawing]

[0014] [Figure 1] This is a rearward perspective view of the ladder. [Figure 2] This is a rear perspective view of the area around the connector of the first ladder section. [Figure 3] This is a rear perspective view of the area around the connector of the second ladder section. [Figure 4] This is a perspective view 1 showing a partially disassembled section around the connector. [Figure 5] This is a perspective view 2 showing a partially disassembled section around the connector. [Figure 6]It is a cross-sectional view showing an exploded state of a part around the connector. [Figure 7] It is a rear perspective view around the connector showing Modification 1. [Figure 8] It is a side view around the connector showing Modification 1. [Figure 9] It is a side view around the connector showing Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a ladder according to an embodiment of the present invention will be described with reference to the drawings. The embodiment described below is an example embodying the present invention, and does not limit the configuration of the present invention by this specific example.

[0016] As shown in FIG. 1, the ladder of the present embodiment is a double ladder whose length can be adjusted by relatively sliding a first ladder portion and a second ladder portion. The ladder comprises: a slide mechanism portion that movably connects the first ladder portion and the second ladder portion to each other in a longitudinal direction; and a hook portion that engages with a predetermined position of the first ladder portion and supports the second ladder portion. The present invention is not limited to double ladders, and can be applied to various ladder structures, including single ladders, triple ladders, step ladders, tripodal ladders, stepping ladders, and work platform ladders.

[0017] FIG. 1 shows the ladder in a state where the second ladder portion is slid to a predetermined extended position. From this state, the second ladder portion is slid along the first ladder portion to a predetermined shortened position, and is disposed overlapping the first ladder portion. This allows the ladder to be co mpactly stored.

[0018] The sliding mechanism 2 has a first pulley 2A and a second pulley 2B. The first pulley 2A is connected and supported near the upper end of the support column 4 of the first ladder section 1A. The second pulley 2B is fixed to the middle part of the support column 4 of the second ladder section 1B. Although not shown in the figures, the first pulley 2A and the second pulley 2B are connected by an operating rope, and the operation of the operating rope causes the first ladder section 1A and the second ladder section 1B to slide relative to each other in the longitudinal direction.

[0019] The hook portion 3 is connected and supported to the middle of the support column 4 of the second ladder portion 1B. The second ladder portion 1B is supported and fixed at a predetermined sliding position of the first ladder portion 1A by engaging the hook portion 3 with a predetermined rung 5 of the first ladder portion 1A. Although not shown in the figure, the hook portion 3 releases its engagement with the rung 5 as appropriate in conjunction with the operation of the operating rope.

[0020] Both the first ladder section 1A and the second ladder section 1B are equipped with a pair of support columns 4 that extend vertically and are arranged side by side with a predetermined interval in the left-right direction, and a plurality of rungs 5 ​​that are horizontally placed between the support columns 4 with a predetermined interval in the vertical direction. In addition, the first ladder section 1A is equipped with anti-slip end fittings 6 at the lower end of each support column 4, and when in use, the anti-slip end fittings 6 are brought into contact with the floor surface to hold it upright.

[0021] In this embodiment, the longitudinal direction of the support column 4 (directions Z1 and Z2 in Figure 1) is the vertical direction, the short direction of the support column 4 and the longitudinal direction of the rung 5 (directions Y1 and Y2 in Figure 1) is the left-right direction, and the short direction of the support column 4 and the direction perpendicular to the longitudinal direction of the rung 5 (directions X1 and X2 in Figure 1) is the front-back direction. In addition, in this embodiment, one side of the first ladder section 1A and the second ladder section 1B is used as the climbing surface for the user. In this ladder 1, the side on which the user climbs up and down (the side X2 in Figure 1) is the rear side, and the opposite side (the side X1 in Figure 1) is the front side.

[0022] As shown in Figures 2 to 5, the support column 4 has multiple (in this case, two) support frame bodies 7 arranged vertically, and a connector 8 that connects and fixes the ends 7e of these support frame bodies 7 together. In this embodiment, both the first ladder section 1A and the second ladder section 1B are constructed by dividing the support column 4 into multiple support frame bodies 7. However, in either the first ladder section 1A or the second ladder section 1B, the support column 4 may be constructed by dividing it into multiple support frame bodies 7, while the other support column 4 is constructed from a single, undivided frame member. Furthermore, the support column 4 is not limited to being constructed by connecting two support frame bodies 7 vertically, but may also be constructed by connecting three or more support frame bodies 7 vertically.

[0023] As shown in Figure 6, the support frame 7 is a frame material with a roughly U-shaped cross-section and has a support side plate 7S that forms the side surface of the support column 4 and a pair of support end plates 7T that form the front and rear surfaces of the support column 4. The support end plates 7T are formed to stand upright at roughly right angles from the long edges 7c of the front and rear of the support side plate 7S, extending in one direction to the left or right. That is, the long corners of the front and rear of the support frame 7 are formed at roughly right angles.

[0024] The support frame 7 of the first ladder section 1A and the support frame 7 of the second ladder section 1B are connected with their open portions R on one side facing each other and their support end plates 7T in close proximity to each other. That is, the support frame 7 of the first ladder section 1A and the support frame 7 of the second ladder section 1B are connected in an eccentric manner in the front-rear direction. In this embodiment, the second ladder section 1B is connected to the front side of the first ladder section 1A. Also in this embodiment, the support side plate 7S of the first ladder section 1A is positioned on the left-right outer side of the ladder 1, and the support side plate 7S of the second ladder section 1B is positioned on the left-right inner side of the ladder 1.

[0025] As shown in Figures 2 and 3, the support columns 4 of the first ladder section 1A are arranged side by side with their openings R facing inward from left to right. On the other hand, the support columns 4 of the second ladder section 1B are arranged with their openings R facing inward from left to right. They are arranged side by side, facing outwards. The rungs 5 ​​are fitted into rung connecting holes 11 opened in the support column side plates 7S. That is, the rungs 5 ​​of the first ladder section 1A are fitted into the rung connecting holes 11 of the support column side plates 7S through the opening R of the support column frame 7. On the other hand, the rungs 5 ​​of the second ladder section 1B are fitted into the rung connecting holes 11 of the support column side plates 7S from the opposite side of the opening R of the support column frame 7.

[0026] Furthermore, as shown in Figures 4 to 6, the support column side plate 7S has bolt insertion holes 12 and guide ribs 13 and 14. The bolt insertion holes 12 are circular through holes, and multiple holes are arranged side by side at a position slightly forward of the center between the front and rear of the support column side plate 7S. In this embodiment, two bolt insertion holes 12 are provided in a vertical direction, near the end 7e of each support column frame 7. Note that three or more bolt insertion holes 12 may be provided near the end 7e of each support column frame 7.

[0027] Guide ribs 13 and 14 are formed to extend vertically along both the outer surface (the surface opposite to the end plate 7T) 7a and the inner surface (the surface on the end plate 7T side) 7b of the support column side plate 7S. In this embodiment, the guide ribs 13 and 14 are arranged side by side on both the front and rear sides of the position where the bolt insertion hole 12 is formed in the support column side plate 7S (reference line L1 shown in Figure 6). Furthermore, the guide ribs (outer ribs) 14 on the outer surface 7a side of the support column side plate 7S are arranged in parallel in the short direction on both the front and rear sides of the support column side plate 7S, with the above reference line L1 in between. The outer ribs 14 are also provided at front-to-back symmetrical positions on the support column side plate 7S. Similarly, the guide ribs (inner ribs) 13 on the inner surface 7b side of the support column side plate 7S are also provided at front-to-back symmetrical positions on the support column side plate 7S. Furthermore, the guide ribs 13 and 14 may be provided only on either the front or rear side of the reference line L1 on the support side plate 7S, or they may be provided on the reference line L1 on the support side plate 7S.

[0028] The connector 8 comprises a first fixing plate 15, a second fixing plate 16, and bolts 17 and nuts 18 as fixing members for connecting and fixing the first fixing plate 15 and the second fixing plate 16 to each other. The first fixing plate 15 is positioned across the ends 7e of the support frame 7 and is aligned with the inner surface 7b of the support side plate 7S. On the other hand, the second fixing plate 16 is positioned across the ends 7e of the support frame 7 and is aligned with the outer surface 7a of the support side plate 7S. The ends 7e of the two support frames 7 are then connected and fixed to each other by fastening the first fixing plate 15 and the second fixing plate 16 to each other from the left and right directions using bolts 17 and nuts 18.

[0029] In this embodiment, the bolt 17 is a so-called hexagon socket low-profile bolt with a head portion 17H formed in a flat disc shape (see Figure 6). The fixing member that connects and fixes the first fixing plate 15 and the second fixing plate 16 may consist of a screw hole formed in either the first fixing plate 15 or the second fixing plate 16 and a fixing screw that is screwed into the screw hole from the outside of the other plate (second fixing plate 16 or first fixing plate 15), provided that it can be easily attached and detached by the user. Alternatively, it may consist of a lock pin inserted through either the first fixing plate 15 or the second fixing plate 16 and a pin engagement portion that engages and holds the lock pin from the outside of the other plate (second fixing plate 16 or first fixing plate 15). In this case, the shaft portion of the fixing screw or the shaft portion of the lock pin becomes a connecting shaft that is inserted between the first fixing plate 15 and the second fixing plate 16 from the plate surface direction.

[0030] The first fixing plate 15 is a plate that is long in the vertical direction and has bolt insertion holes 21, a rotation stopper 22, and an engagement groove 23. The bolt insertion holes 21 are circular through holes and multiple holes are arranged side by side in the vertical direction of the first fixing plate 15. The bolt insertion holes 21 are also provided in positions that overlap with the bolt insertion holes 12 of each support frame 7 when the first fixing plate 15 is positioned at a predetermined position on the inner surface 7b of the support side plate 7S, straddling the support frame 7. In this embodiment, there are a total of four bolt insertion holes 21 arranged in a line in the vertical direction: two overlapping with the bolt insertion holes 12 of one support frame 7 and two overlapping with the bolt insertion holes 12 of the other support frame 7. In this embodiment, the first fixing plate 15 is positioned in front of the center position between the front and rear. A bolt insertion hole 21 is provided at an eccentric position toward the left. Therefore, when the first fixing plate 15 is placed face-to-face with the inner surface 7b of the support side plate 7S such that the bolt insertion hole 21 overlaps with the bolt insertion hole 12 of the support frame 7, the rear end edge is positioned close to the inner surface of the rear support end plate 7T, and the front end edge is positioned spaced apart from the inner surface of the front support end plate 7T.

[0031] The rotation stoppers 22 are formed in pairs on both the front and rear sides of the bolt insertion hole 21 on one of the outer surfaces 15a of the first fixing plate 15, extending vertically. The spacing between the rotation stoppers 22 is set to be approximately the same as the width across the two sides of the outer circumference of the nut 18. Note that the rotation stoppers 22 may be provided only on one side of the bolt insertion hole 21 on the outer surface 15a of the first fixing plate 15, as long as they can adequately restrain the rotation of the nut 18.

[0032] The engagement groove 23 extends vertically along the other plate surface (inner surface) 15b of the first fixing plate 15, and when the first fixing plate 15 is placed face-to-face with the inner surface 7b of the support column side plate 7S, the inner rib 13 of the support column side plate 7S is fitted into it. As a result, the first fixing plate 15 is positioned and held in the front-rear direction relative to the inner surface 7b of the support column side plate 7S. In this embodiment, the engagement groove 23 is arranged side by side on both the front and rear sides of the bolt insertion hole 21. The engagement groove 23 may be provided only on one side of the bolt insertion hole 21, or it may be provided in a position that overlaps with the bolt insertion hole 21, in accordance with the arrangement of the inner rib 13 of the support column side plate 7S.

[0033] The second fixing plate 16 is a vertically elongated plate and has bolt insertion holes 24, raised portions 25, engagement grooves 26, and auxiliary ribs 27. The bolt insertion holes 24 are circular through holes and multiple holes are arranged side by side in the vertical direction of the second fixing plate 16. The bolt insertion holes 24 are also provided in positions that overlap with the bolt insertion holes 12 of each support frame 7 when the second fixing plate 16 is positioned at a predetermined location on the outer surface 7a of the support side plate 7S, straddling the support frame 7. In this embodiment, there are a total of four bolt insertion holes 24 arranged in a vertical line: two overlapping with the bolt insertion holes 12 of one support frame 7 and two overlapping with the bolt insertion holes 12 of the other support frame 7.

[0034] Furthermore, the bolt 17 is inserted through the bolt insertion holes 24, 12, and 21 of the second fixing plate 16, the support column side plate 7S, and the first fixing plate 15, respectively, from the outside of one of the plate surfaces (outer surface) 16a of the second fixing plate 16. That is, the shaft 17J is inserted through the first fixing plate 15 and the second fixing plate 16 from the plate surface direction as a connecting shaft. This holds the ends 7e of the support column frame 7 in a butt-to-butt state. On the other hand, the nut 18 is screwed onto the shaft 17J protruding from the bolt insertion hole 21 of the first fixing plate 15 from the plate surface direction of the first fixing plate 15. In this embodiment, the first fixing plate 15 and the second fixing plate 16 are connected and fixed to the support column frame 7 by four fixing members (bolts 17 and nuts 18) arranged in the vertical direction.

[0035] The raised portion 25 is formed in pairs on both the front and rear sides of the bolt insertion hole 21 on the outer surface 16a of the second fixing plate 16, extending vertically. Furthermore, the raised portion 25 is formed in a roughly trapezoidal shape when viewed from above, rising outward from the head portion 17H of the bolt 17 (see Figure 6). This makes it difficult for external objects to collide with the head portion 17H or for a user's hand to get caught on it. In addition, although not shown, the top surface (upper bottom) of the raised portion 25 has multiple ridge-like indentations that extend vertically (longitudinal direction) and are arranged parallel to each other in the front-to-back direction (short direction), ensuring a uniform appearance with the outer rib 14 of the support side plate 7S. The raised portion 25 may be provided only on one side of the bolt insertion hole 21 on the outer surface 15a of the first fixing plate 15, as long as it is possible to suppress collisions of external objects with the head portion 17H and for a hand to get caught on it.

[0036] The engagement groove 26 is formed to extend vertically along the other plate surface portion (inner surface) 16b of the second fixing plate 16, and when the second fixing plate 16 is placed face-to-face with the outer surface 7a of the support column side plate 7S, the outer rib 14 of the support column side plate 7S is fitted into it. As a result, the second fixing plate 16 is positioned and held in the front-rear direction relative to the outer surface 7a of the support column side plate 7S. In this embodiment, the engagement grooves 26 are arranged side by side on both the front and rear sides of the bolt insertion hole 24. The engagement grooves 26 may be provided only on one side of the bolt insertion hole 24, or they may be provided in a position that overlaps with the bolt insertion hole 24, in accordance with the arrangement of the outer rib 14 of the support column side plate 7S.

[0037] The auxiliary rib 27 is formed to protrude approximately perpendicularly from one of the long edges 16c on the outer edge of the second fixing plate 16, in the left-right direction, along the long edge 16c on one of the front or rear sides. In this embodiment, the auxiliary rib 27 is provided to protrude along the front long edge 16c of the second fixing plate 16, which is on the opposite side of the ladder 1 from where the user ascends or descends. Therefore, when the second fixing plate 16 is placed face-to-face with the outer surface 7a of the support column side plate 7S as described above, the auxiliary rib 27 straddles the ends 7e of the support column frame 7 and engages with the long edge 7c of the support column side plate 7S, that is, the front long edge corner of the support column frame 7, from the outside in the front-rear direction. This suppresses displacement and bending of the ends 7e of the support column frame 7 in the front-rear direction.

[0038] Furthermore, in this embodiment, since the auxiliary rib 27 is provided only on one of the long edges 16c of the front and rear of the second fixing plate 16, after overlapping the second fixing plate 16 with the outer surface 7a of the support column side plate 7S, the auxiliary rib 27 can be reliably brought into contact with and engaged with the long edge 7c of the support column side plate 7S by sliding the second fixing plate 16 in one direction along the outer surface 7a. Note that the auxiliary rib 27 may be provided on both the front and rear long edges 16c of the second fixing plate 16, or it may be provided only on the rear long edge 16c of the second fixing plate 16, as long as it can reliably come into contact with and engage with the long edge 7c of the support column side plate 7S.

[0039] Furthermore, in this embodiment, since the bolt insertion holes 12 are formed slightly forward of the center between the front and rear of the support column side plate 7S, even if a user mistakenly attempts to attach the second fixing plate 16 to the outer surface 7a of the support column side plate 7S in the opposite direction, the auxiliary rib 27 interferes with the support column side plate 7S, preventing the bolt insertion holes 12 and 24 from being aligned and overlapped. Similarly, even if a user attempts to attach the first fixing plate 15 to the inner surface 7b of the support column side plate 7S in the opposite direction, one of the front and rear edges of the first fixing plate 15 interferes with the support column end plate 7T, preventing the bolt insertion holes 12 and 21 from being aligned and overlapped. This reliably prevents the support column frames 7 from being connected in an improper manner.

[0040] As shown in Figure 6, the auxiliary rib 27 is formed such that the front-to-back width of the base end (auxiliary rib base end) 27a is larger than the front-to-back width of the tip end (auxiliary rib tip) 27b. This improves the overall rigidity of the auxiliary rib 27. In this embodiment, the front-to-back width dimension of the auxiliary rib base end 27a is set to 3 / 2 of the front-to-back width dimension of the auxiliary rib tip 27b.

[0041] As described above, in this embodiment, the ladder 1 has multiple bolt insertion holes 12 through the support side plates 7S of the upper and lower support frame 7 (see Figures 4 and 5), and bolts 17 and nuts 18 are screwed together through these bolt insertion holes 12. Specifically, first, the ends 7e of both support frame 7 are brought together, and the first fixing plate 15 and the second fixing plate 16 are placed facing each other from the left and right directions and overlapped with each support side plate 7S. Then, in this state, the positions of the bolt insertion holes 21 and 24 of the first fixing plate 15 and the second fixing plate 16 are aligned with the positions of the bolt insertion holes 12 of the support side plate 7S, and then bolts 17 are inserted through the bolt insertion holes 12, 21 and 24 from the outside of the second fixing plate 16, and nuts 18 are screwed onto these bolts 17 from the outside of the first fixing plate 15. In this way, the upper and lower support frame 7 are firmly connected and fixed together.

[0042] <Example 1> On the other hand, in the ladder 1 shown in Figures 7 and 8, a connecting slit 32 is formed in place of a bolt insertion hole 12 on the short end face 31 of the support side plate 7S of one of the first support frame 71 of the support frame 7. The first support frame 71 is configured to be inserted into the second support frame 72 and then fixed in place after the connector 8 has been temporarily secured to it.

[0043] More specifically, the first support frame 71 has a connecting slit 32 in the short end face (butt end face) 31 of the support side plate 7S, instead of a bolt insertion hole 12. The connecting slit 32 is a notch with approximately the same width as the diameter of the shaft portion 17J of the bolt 17, and extends vertically from the butt end face 31. Therefore, when the first support frame 71 is connected to the second support frame 72 in a butt-jointed state from above and below, the shaft portion 17J is inserted along the connecting slit 32.

[0044] In this embodiment, the connecting slit 32 is formed in a substantially F-shape when viewed from the side, and has a guide portion 32A that extends vertically from the abutting end face 31, and a engage portion 32B that extends in one direction (in this case, backward) from the end position and intermediate position of the guide portion 32A.

[0045] The guide portion 32A is positioned eccentrically in one direction (in this case, forward) from the end center position of the engaging portion 32B on the support column side plate 7S (reference line L2 shown in Figure 8). That is, the guide portion 32A is positioned where the shaft portion 17J is inserted when the first support column frame 71 is connected to the second support column frame 72 with the first support column frame 71 shifted in one direction (in this case, backward).

[0046] The engaging portion 32B is provided vertically on the reference line L2 of the first support frame 71. That is, the engaging portion 32B is provided at a position where the shaft portion 17J is inserted and engaged when the first support frame 71 and the second support frame 72 are connected in a straight line.

[0047] In this configuration, first, the first fixing plate 15 and the second fixing plate 16 are placed facing each other from the left and right directions and superimposed on the support side plate 7S of the second support frame 72, and the positions of the bolt insertion holes 12, 21, and 24 are aligned, and the bolts 17 and nuts 18 are screwed in through these bolt insertion holes 12, 21, and 24. As a result, the connector 8 is temporarily connected and held to the end 7e of the second support frame 72.

[0048] Next, with the first support frame 71 shifted in one direction relative to the second support frame 72, it is inserted into the gap S1 between the opposing surfaces of the first fixing plate 15 and the second fixing plate 16 (see Figure 8). As a result, the shafts 17J of the two bolts 17 on one side (in this case, the upper side) of the connector 8 are guided by the guide portion 32A of the connecting slit 32, and the two support frames 7 are in a temporary connected state with their ends 7e shifted in the front-to-back direction and butted together.

[0049] From this temporary connection state, the first support frame 71 is further slid along the abutting end face 31 of the second support frame 72 in the opposite direction to the aforementioned displacement until the long edge 7c of the support side plate 7S contacts the auxiliary rib 27. As a result, the two shaft portions 17J are guided to the engaging portion 32B of the connecting slit 32, and the two support frames 7 are connected in an engaging state with their support end plates 7T aligned front to back and in a straight line vertically. In this state, the upper and lower support frames 7 are firmly connected and fixed to each other by tightening the bolts 17 and nuts 18.

[0050] <Modification 2> Furthermore, in the ladder 1 shown in Figure 9, the connecting slit 33 is formed to extend diagonally in the vertical direction from the short end face 31 of the support side plate 7S of the first support frame 71, and after temporarily fastening the connector 8 to the other second support frame 72, the first support frame 71 is tilted relative to the connector 8. The first support frame 71 can be inserted in this state and then rotated so that it is in a straight line with the second support frame 72, thereby enabling connection and fixation.

[0051] More specifically, the connecting slit 33 of this embodiment has a guide portion 33A that extends from the short end face (butt end face) 31 of the support column side plate 7S, inclined in the vertical direction and in one of the front-to-back directions (in this case, rearward), and a engage portion 33B that extends from the terminal position and intermediate position of the guide portion 33A in both the front-to-back directions, respectively.

[0052] The guide portion 33A is formed to extend from one end center position (in this case, forward) of the engagement portion 33B on the support side plate 7S (reference line L2 shown in Figure 8) through the space between the engagement portions 33B to the other end center position (in this case, backward).

[0053] The engaging portion 33B is provided vertically on the reference line L2 of the first support frame 71. That is, the engaging portion 33B is provided in a position where the shaft portion 17J is inserted and engaged when the first support frame 71 and the second support frame 72 are connected in a straight line.

[0054] In this configuration, first, the connector 8 is temporarily attached to the end 7e of the second support frame 72 as described in the above embodiment. Then, by inserting the first support frame 71 through the gap S1 of the connector 8 while it is tilted in the front-to-back direction (forward in this case), the shaft portions 17J of the two bolts 17 on one side (upper side in this case) of the connector 8 are guided to the guide portion 33A of the connecting slit 33, resulting in a temporary connection. Furthermore, by rotating the first support frame 71 in the opposite direction to the tilt direction (rearward in this case), the two shaft portions 17J are guided from the front-to-back direction to the engaging portion 33B of the connecting slit 33. As a result, the two support frame bodies 7 are connected in an engaging state with their support end plates 7T aligned front-to-back and aligned in a straight line vertically. In this state, the upper and lower support frame bodies 7 are firmly connected and fixed to each other by tightening the bolts 17 and nuts 18.

[0055] Thus, the ladder 1 of the above embodiment comprises a pair of left and right support columns 4 extending in the vertical direction and arranged side by side with a predetermined interval in the left-right direction, and a plurality of rungs 5 ​​horizontally placed between the support columns 4, wherein the support columns 4 have a plurality of support column frames 7 and a connector 8 that connects the ends 7e of the support column frames 7 in a butted state, and the support column frame 7 has a support column side plate 7S that constitutes the side surface of the support column 4, and a pair of support column end plates 7T that are formed to stand up in one left-right direction from the long edges 7c of the support column side plate 7S, The fastener 8 includes a first fixing plate 15 that spans between the ends 7e and is positioned face-to-face with the surface 7b of the support side plate 7S on the side of the support end plate 7T, a second fixing plate 16 that spans between the ends 7e and is positioned face-to-face with the surface 7a of the support side plate 7S opposite to the support end plate 7T, and fixing members 17 and 18 that connect and fix the first fixing plate 15 and the second fixing plate 16 to each other. The second fixing plate 16 has an auxiliary rib 27 that protrudes along its outer edge and engages with the long edge 7c of the support side plate 7S from the outside in the front-rear direction.

[0056] With this configuration, the auxiliary ribs 27 protruding from the outer edge of the second fixing plate 16 are brought into contact and engaged with the long edge 7c of the support column side plate 7S, that is, along the long edge corner of the support column frame 7, from the outside in the front-rear direction, and the support column frames 7 can be connected and fixed to each other by the first fixing plate 15 and the second fixing plate 16, thereby significantly improving the connection stability of the support columns 4.

[0057] Moreover, with this design, the support frame bodies 7 can be connected and fixed to each other while the auxiliary ribs 27 are in contact with and engaged with the long edge corners of the support frame bodies 7 as described above. Therefore, it is not necessary to arrange more fixing members 17 and 18 than necessary to connect and fix the first fixing plate 15 and the second fixing plate 16. In other words, the number of fixing members 17 and 18 can be minimized. Consequently, the ease of assembly is greatly improved.

[0058] Furthermore, in the ladder 1 described above, the side on which the user ascends and descends is the rear side, and the opposite side is the front side. The second fixing plate 16 has auxiliary ribs 27 protruding along the front outer edge 16c. When the user ascends and descends the ladder 1, a large load is applied to the abutting joints of the ends 7e of the support frame 7 in a direction that causes them to bend forward. However, in this design, the auxiliary ribs 27 abut and engage with the long edge 7c of the support side plate 7S from the front outside, so that misalignment and bending of the abutting joints can be reliably suppressed. This further improves the connection stability of the support 4.

[0059] Furthermore, the auxiliary rib 27 is formed with a greater front-to-back width at its base than at its tip. This design makes it less likely for the auxiliary rib 27 to warp or distort in the front-to-back direction, thus reliably suppressing misalignment and bending at the abutting joint. This further improves the connection stability of the support column 4.

[0060] Furthermore, in the ladder 1 of the second embodiment shown as Modification 1, and the ladder 1 of the third embodiment shown as Modification 2, the fixing members 17 and 18 have a connecting shaft 17J that is inserted through the first fixing plate 15 and the second fixing plate 16 from the plate surface direction, and one of the support frame bodies 7, the first support frame body 71, is formed to extend vertically from the end face 31 on the short side of the support side plate 7S, and has connecting slits 32 and 33 through which the connecting shaft 17J is inserted when the first support frame body 71 is connected to the other second support frame body 72.

[0061] In this design, when connecting the support frame bodies 7 to each other, the connector 8 is first temporarily attached and held to the end 7e of the second support frame body 72, and then the first support frame body 71 can be connected and fixed to the connector 8 in that state, thus further improving the ease of assembly.

[0062] Furthermore, in the ladder 1 of the second embodiment shown as Modification 1, the connecting slit 32 has a guide portion 32A through which the connecting shaft 17J is inserted when the first support frame 71 is connected to the second support frame 72 with the first support frame offset to one side in the front-rear direction, and a engage portion 32B which is formed to extend from the guide portion 32A to one side in the front-rear direction, and through which the connecting shaft 17J is inserted and engaged when the first support frame 71 and the second support frame 72 are connected in a straight line.

[0063] In this design, when connecting the support frame bodies 7 to each other, the first support frame body 71 is initially offset to the second support frame body 72 in one direction in the front-rear direction and then moved in the opposite direction to the offset direction. This causes the connecting shaft 17J to be inserted into and engaged with the engaging portion 32B of the connecting slit 32, resulting in the first support frame body 71 being aligned in a straight line with respect to the second support frame body 72 and thus enabling the realization of a ladder 1 with even better assembly workability. [Explanation of Symbols]

[0064] 1 ladder 1A 1st ladder section 1B 2nd ladder section 4 pillars 5 steps 7. Support frame 7e end 7S pillar side plate 7T post end plate 8 Connectors 15 1st fixing plate 16 Second fixing plate 17 Bolts (fixing members) 18. Nut (fixing component) 27 Auxiliary ribs

Claims

1. A ladder comprising a pair of left and right support columns extending vertically and arranged side by side at a predetermined interval in the left-right direction, and a plurality of rungs horizontally between the support columns, wherein the support columns each have a plurality of support column frames and a connecting device that connects the ends of the support column frames in a butted state, The support frame comprises a support side plate that forms the side surface of the support column, and a pair of support end plates that are formed along both long edges of the support side plate, extending upward from the long edges in one direction to the left or right. The connector comprises a first fixing plate positioned across the ends and facing the side of the support plate on the support end plate side of the support plate, a second fixing plate positioned across the ends and facing the side of the support plate on the opposite side of the support end plate of the support plate, and a fixing member for connecting and fixing the first fixing plate and the second fixing plate to each other. In the aforementioned ladder, the side on which the user ascends and descends is the rear side, and the opposite side is the front side. The ladder has an auxiliary rib that is formed in a rib shape along the front outer edge of the front and rear outer edges of the second fixing plate, protruding in one direction to the left or right from the outer edge, and that abuts and engages with the front long corner of the front side of the support column side plate from the front outer side of the long corner.

2. The ladder according to claim 1, wherein the auxiliary rib is formed so that the front-to-back width of the base end is greater than the front-to-back width of the tip end.

3. The fixing member has a connecting shaft that is inserted through the first fixing plate and the second fixing plate from the direction of the plate surface, The ladder according to claim 1 or 2, wherein one of the support frame members, the first support frame member, is formed to extend vertically from the end face on the shorter side of the support side plate, and has a connecting slit through which the connecting shaft is inserted when the first support frame member is connected to the other second support frame member.

4. The ladder according to claim 3, wherein the connecting slit has a guide portion through which the connecting shaft is inserted when the first support frame is connected to the second support frame with the first support frame offset to one side in the front-rear direction, and a engage portion that extends from the guide portion to one side in the front-rear direction, and through which the connecting shaft is inserted and engaged when the first support frame and the second support frame are connected in a straight line.

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